[DEV] add v1.76.0

doc/html/boost_asio/example/cpp03/allocation/server.cpp

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+//
+// server.cpp
+// ~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <cstdlib>
+#include <iostream>
+#include <boost/aligned_storage.hpp>
+#include <boost/array.hpp>
+#include <boost/bind/bind.hpp>
+#include <boost/enable_shared_from_this.hpp>
+#include <boost/noncopyable.hpp>
+#include <boost/shared_ptr.hpp>
+#include <boost/asio.hpp>
+
+using boost::asio::ip::tcp;
+
+// Class to manage the memory to be used for handler-based custom allocation.
+// It contains a single block of memory which may be returned for allocation
+// requests. If the memory is in use when an allocation request is made, the
+// allocator delegates allocation to the global heap.
+class handler_memory
+  : private boost::noncopyable
+{
+public:
+  handler_memory()
+    : in_use_(false)
+  {
+  }
+
+  void* allocate(std::size_t size)
+  {
+    if (!in_use_ && size < storage_.size)
+    {
+      in_use_ = true;
+      return storage_.address();
+    }
+    else
+    {
+      return ::operator new(size);
+    }
+  }
+
+  void deallocate(void* pointer)
+  {
+    if (pointer == storage_.address())
+    {
+      in_use_ = false;
+    }
+    else
+    {
+      ::operator delete(pointer);
+    }
+  }
+
+private:
+  // Storage space used for handler-based custom memory allocation.
+  boost::aligned_storage<1024> storage_;
+
+  // Whether the handler-based custom allocation storage has been used.
+  bool in_use_;
+};
+
+// The allocator to be associated with the handler objects. This allocator only
+// needs to satisfy the C++11 minimal allocator requirements, plus rebind when
+// targeting C++03.
+template <typename T>
+class handler_allocator
+{
+public:
+  typedef T value_type;
+
+  explicit handler_allocator(handler_memory& mem)
+    : memory_(mem)
+  {
+  }
+
+  template <typename U>
+  handler_allocator(const handler_allocator<U>& other)
+    : memory_(other.memory_)
+  {
+  }
+
+  template <typename U>
+  struct rebind
+  {
+    typedef handler_allocator<U> other;
+  };
+
+  bool operator==(const handler_allocator& other) const
+  {
+    return &memory_ == &other.memory_;
+  }
+
+  bool operator!=(const handler_allocator& other) const
+  {
+    return &memory_ != &other.memory_;
+  }
+
+  T* allocate(std::size_t n) const
+  {
+    return static_cast<T*>(memory_.allocate(sizeof(T) * n));
+  }
+
+  void deallocate(T* p, std::size_t /*n*/) const
+  {
+    return memory_.deallocate(p);
+  }
+
+//private:
+  // The underlying memory.
+  handler_memory& memory_;
+};
+
+// Wrapper class template for handler objects to allow handler memory
+// allocation to be customised. The allocator_type typedef and get_allocator()
+// member function are used by the asynchronous operations to obtain the
+// allocator. Calls to operator() are forwarded to the encapsulated handler.
+template <typename Handler>
+class custom_alloc_handler
+{
+public:
+  typedef handler_allocator<Handler> allocator_type;
+
+  custom_alloc_handler(handler_memory& m, Handler h)
+    : memory_(m),
+      handler_(h)
+  {
+  }
+
+  allocator_type get_allocator() const
+  {
+    return allocator_type(memory_);
+  }
+
+  template <typename Arg1>
+  void operator()(Arg1 arg1)
+  {
+    handler_(arg1);
+  }
+
+  template <typename Arg1, typename Arg2>
+  void operator()(Arg1 arg1, Arg2 arg2)
+  {
+    handler_(arg1, arg2);
+  }
+
+private:
+  handler_memory& memory_;
+  Handler handler_;
+};
+
+// Helper function to wrap a handler object to add custom allocation.
+template <typename Handler>
+inline custom_alloc_handler<Handler> make_custom_alloc_handler(
+    handler_memory& m, Handler h)
+{
+  return custom_alloc_handler<Handler>(m, h);
+}
+
+class session
+  : public boost::enable_shared_from_this<session>
+{
+public:
+  session(boost::asio::io_context& io_context)
+    : socket_(io_context)
+  {
+  }
+
+  tcp::socket& socket()
+  {
+    return socket_;
+  }
+
+  void start()
+  {
+    socket_.async_read_some(boost::asio::buffer(data_),
+        make_custom_alloc_handler(handler_memory_,
+          boost::bind(&session::handle_read,
+            shared_from_this(),
+            boost::asio::placeholders::error,
+            boost::asio::placeholders::bytes_transferred)));
+  }
+
+  void handle_read(const boost::system::error_code& error,
+      size_t bytes_transferred)
+  {
+    if (!error)
+    {
+      boost::asio::async_write(socket_,
+          boost::asio::buffer(data_, bytes_transferred),
+          make_custom_alloc_handler(handler_memory_,
+            boost::bind(&session::handle_write,
+              shared_from_this(),
+              boost::asio::placeholders::error)));
+    }
+  }
+
+  void handle_write(const boost::system::error_code& error)
+  {
+    if (!error)
+    {
+      socket_.async_read_some(boost::asio::buffer(data_),
+          make_custom_alloc_handler(handler_memory_,
+            boost::bind(&session::handle_read,
+              shared_from_this(),
+              boost::asio::placeholders::error,
+              boost::asio::placeholders::bytes_transferred)));
+    }
+  }
+
+private:
+  // The socket used to communicate with the client.
+  tcp::socket socket_;
+
+  // Buffer used to store data received from the client.
+  boost::array<char, 1024> data_;
+
+  // The memory to use for handler-based custom memory allocation.
+  handler_memory handler_memory_;
+};
+
+typedef boost::shared_ptr<session> session_ptr;
+
+class server
+{
+public:
+  server(boost::asio::io_context& io_context, short port)
+    : io_context_(io_context),
+      acceptor_(io_context, tcp::endpoint(tcp::v4(), port))
+  {
+    session_ptr new_session(new session(io_context_));
+    acceptor_.async_accept(new_session->socket(),
+        boost::bind(&server::handle_accept, this, new_session,
+          boost::asio::placeholders::error));
+  }
+
+  void handle_accept(session_ptr new_session,
+      const boost::system::error_code& error)
+  {
+    if (!error)
+    {
+      new_session->start();
+    }
+
+    new_session.reset(new session(io_context_));
+    acceptor_.async_accept(new_session->socket(),
+        boost::bind(&server::handle_accept, this, new_session,
+          boost::asio::placeholders::error));
+  }
+
+private:
+  boost::asio::io_context& io_context_;
+  tcp::acceptor acceptor_;
+};
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    if (argc != 2)
+    {
+      std::cerr << "Usage: server <port>\n";
+      return 1;
+    }
+
+    boost::asio::io_context io_context;
+
+    using namespace std; // For atoi.
+    server s(io_context, atoi(argv[1]));
+
+    io_context.run();
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << "Exception: " << e.what() << "\n";
+  }
+
+  return 0;
+}

doc/html/boost_asio/example/cpp03/buffers/reference_counted.cpp

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+//
+// reference_counted.cpp
+// ~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <boost/asio.hpp>
+#include <boost/bind/bind.hpp>
+#include <boost/enable_shared_from_this.hpp>
+#include <boost/shared_ptr.hpp>
+#include <iostream>
+#include <vector>
+
+using boost::asio::ip::tcp;
+
+// A reference-counted non-modifiable buffer class.
+class shared_const_buffer
+{
+public:
+  // Construct from a std::string.
+  explicit shared_const_buffer(const std::string& data)
+    : data_(new std::vector<char>(data.begin(), data.end())),
+      buffer_(boost::asio::buffer(*data_))
+  {
+  }
+
+  // Implement the ConstBufferSequence requirements.
+  typedef boost::asio::const_buffer value_type;
+  typedef const boost::asio::const_buffer* const_iterator;
+  const boost::asio::const_buffer* begin() const { return &buffer_; }
+  const boost::asio::const_buffer* end() const { return &buffer_ + 1; }
+
+private:
+  boost::shared_ptr<std::vector<char> > data_;
+  boost::asio::const_buffer buffer_;
+};
+
+class session
+  : public boost::enable_shared_from_this<session>
+{
+public:
+  session(boost::asio::io_context& io_context)
+    : socket_(io_context)
+  {
+  }
+
+  tcp::socket& socket()
+  {
+    return socket_;
+  }
+
+  void start()
+  {
+    using namespace std; // For time_t, time and ctime.
+    time_t now = time(0);
+    shared_const_buffer buffer(ctime(&now));
+    boost::asio::async_write(socket_, buffer,
+        boost::bind(&session::handle_write, shared_from_this()));
+  }
+
+  void handle_write()
+  {
+  }
+
+private:
+  // The socket used to communicate with the client.
+  tcp::socket socket_;
+};
+
+typedef boost::shared_ptr<session> session_ptr;
+
+class server
+{
+public:
+  server(boost::asio::io_context& io_context, short port)
+    : io_context_(io_context),
+      acceptor_(io_context, tcp::endpoint(tcp::v4(), port))
+  {
+    session_ptr new_session(new session(io_context_));
+    acceptor_.async_accept(new_session->socket(),
+        boost::bind(&server::handle_accept, this, new_session,
+          boost::asio::placeholders::error));
+  }
+
+  void handle_accept(session_ptr new_session,
+      const boost::system::error_code& error)
+  {
+    if (!error)
+    {
+      new_session->start();
+    }
+
+    new_session.reset(new session(io_context_));
+    acceptor_.async_accept(new_session->socket(),
+        boost::bind(&server::handle_accept, this, new_session,
+          boost::asio::placeholders::error));
+  }
+
+private:
+  boost::asio::io_context& io_context_;
+  tcp::acceptor acceptor_;
+};
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    if (argc != 2)
+    {
+      std::cerr << "Usage: reference_counted <port>\n";
+      return 1;
+    }
+
+    boost::asio::io_context io_context;
+
+    using namespace std; // For atoi.
+    server s(io_context, atoi(argv[1]));
+
+    io_context.run();
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << "Exception: " << e.what() << "\n";
+  }
+
+  return 0;
+}

doc/html/boost_asio/example/cpp03/chat/chat_client.cpp

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+//
+// chat_client.cpp
+// ~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <cstdlib>
+#include <deque>
+#include <iostream>
+#include <boost/bind/bind.hpp>
+#include <boost/asio.hpp>
+#include <boost/thread/thread.hpp>
+#include "chat_message.hpp"
+
+using boost::asio::ip::tcp;
+
+typedef std::deque<chat_message> chat_message_queue;
+
+class chat_client
+{
+public:
+  chat_client(boost::asio::io_context& io_context,
+      const tcp::resolver::results_type& endpoints)
+    : io_context_(io_context),
+      socket_(io_context)
+  {
+    boost::asio::async_connect(socket_, endpoints,
+        boost::bind(&chat_client::handle_connect, this,
+          boost::asio::placeholders::error));
+  }
+
+  void write(const chat_message& msg)
+  {
+    boost::asio::post(io_context_,
+        boost::bind(&chat_client::do_write, this, msg));
+  }
+
+  void close()
+  {
+    boost::asio::post(io_context_,
+        boost::bind(&chat_client::do_close, this));
+  }
+
+private:
+
+  void handle_connect(const boost::system::error_code& error)
+  {
+    if (!error)
+    {
+      boost::asio::async_read(socket_,
+          boost::asio::buffer(read_msg_.data(), chat_message::header_length),
+          boost::bind(&chat_client::handle_read_header, this,
+            boost::asio::placeholders::error));
+    }
+  }
+
+  void handle_read_header(const boost::system::error_code& error)
+  {
+    if (!error && read_msg_.decode_header())
+    {
+      boost::asio::async_read(socket_,
+          boost::asio::buffer(read_msg_.body(), read_msg_.body_length()),
+          boost::bind(&chat_client::handle_read_body, this,
+            boost::asio::placeholders::error));
+    }
+    else
+    {
+      do_close();
+    }
+  }
+
+  void handle_read_body(const boost::system::error_code& error)
+  {
+    if (!error)
+    {
+      std::cout.write(read_msg_.body(), read_msg_.body_length());
+      std::cout << "\n";
+      boost::asio::async_read(socket_,
+          boost::asio::buffer(read_msg_.data(), chat_message::header_length),
+          boost::bind(&chat_client::handle_read_header, this,
+            boost::asio::placeholders::error));
+    }
+    else
+    {
+      do_close();
+    }
+  }
+
+  void do_write(chat_message msg)
+  {
+    bool write_in_progress = !write_msgs_.empty();
+    write_msgs_.push_back(msg);
+    if (!write_in_progress)
+    {
+      boost::asio::async_write(socket_,
+          boost::asio::buffer(write_msgs_.front().data(),
+            write_msgs_.front().length()),
+          boost::bind(&chat_client::handle_write, this,
+            boost::asio::placeholders::error));
+    }
+  }
+
+  void handle_write(const boost::system::error_code& error)
+  {
+    if (!error)
+    {
+      write_msgs_.pop_front();
+      if (!write_msgs_.empty())
+      {
+        boost::asio::async_write(socket_,
+            boost::asio::buffer(write_msgs_.front().data(),
+              write_msgs_.front().length()),
+            boost::bind(&chat_client::handle_write, this,
+              boost::asio::placeholders::error));
+      }
+    }
+    else
+    {
+      do_close();
+    }
+  }
+
+  void do_close()
+  {
+    socket_.close();
+  }
+
+private:
+  boost::asio::io_context& io_context_;
+  tcp::socket socket_;
+  chat_message read_msg_;
+  chat_message_queue write_msgs_;
+};
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    if (argc != 3)
+    {
+      std::cerr << "Usage: chat_client <host> <port>\n";
+      return 1;
+    }
+
+    boost::asio::io_context io_context;
+
+    tcp::resolver resolver(io_context);
+    tcp::resolver::results_type endpoints = resolver.resolve(argv[1], argv[2]);
+
+    chat_client c(io_context, endpoints);
+
+    boost::thread t(boost::bind(&boost::asio::io_context::run, &io_context));
+
+    char line[chat_message::max_body_length + 1];
+    while (std::cin.getline(line, chat_message::max_body_length + 1))
+    {
+      using namespace std; // For strlen and memcpy.
+      chat_message msg;
+      msg.body_length(strlen(line));
+      memcpy(msg.body(), line, msg.body_length());
+      msg.encode_header();
+      c.write(msg);
+    }
+
+    c.close();
+    t.join();
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << "Exception: " << e.what() << "\n";
+  }
+
+  return 0;
+}

doc/html/boost_asio/example/cpp03/chat/chat_message.hpp

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+//
+// chat_message.hpp
+// ~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef CHAT_MESSAGE_HPP
+#define CHAT_MESSAGE_HPP
+
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+
+class chat_message
+{
+public:
+  enum { header_length = 4 };
+  enum { max_body_length = 512 };
+
+  chat_message()
+    : body_length_(0)
+  {
+  }
+
+  const char* data() const
+  {
+    return data_;
+  }
+
+  char* data()
+  {
+    return data_;
+  }
+
+  size_t length() const
+  {
+    return header_length + body_length_;
+  }
+
+  const char* body() const
+  {
+    return data_ + header_length;
+  }
+
+  char* body()
+  {
+    return data_ + header_length;
+  }
+
+  size_t body_length() const
+  {
+    return body_length_;
+  }
+
+  void body_length(size_t new_length)
+  {
+    body_length_ = new_length;
+    if (body_length_ > max_body_length)
+      body_length_ = max_body_length;
+  }
+
+  bool decode_header()
+  {
+    using namespace std; // For strncat and atoi.
+    char header[header_length + 1] = "";
+    strncat(header, data_, header_length);
+    body_length_ = atoi(header);
+    if (body_length_ > max_body_length)
+    {
+      body_length_ = 0;
+      return false;
+    }
+    return true;
+  }
+
+  void encode_header()
+  {
+    using namespace std; // For sprintf and memcpy.
+    char header[header_length + 1] = "";
+    sprintf(header, "%4d", static_cast<int>(body_length_));
+    memcpy(data_, header, header_length);
+  }
+
+private:
+  char data_[header_length + max_body_length];
+  size_t body_length_;
+};
+
+#endif // CHAT_MESSAGE_HPP

doc/html/boost_asio/example/cpp03/chat/chat_server.cpp

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+//
+// chat_server.cpp
+// ~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <algorithm>
+#include <cstdlib>
+#include <deque>
+#include <iostream>
+#include <list>
+#include <set>
+#include <boost/bind/bind.hpp>
+#include <boost/shared_ptr.hpp>
+#include <boost/enable_shared_from_this.hpp>
+#include <boost/asio.hpp>
+#include "chat_message.hpp"
+
+using boost::asio::ip::tcp;
+
+//----------------------------------------------------------------------
+
+typedef std::deque<chat_message> chat_message_queue;
+
+//----------------------------------------------------------------------
+
+class chat_participant
+{
+public:
+  virtual ~chat_participant() {}
+  virtual void deliver(const chat_message& msg) = 0;
+};
+
+typedef boost::shared_ptr<chat_participant> chat_participant_ptr;
+
+//----------------------------------------------------------------------
+
+class chat_room
+{
+public:
+  void join(chat_participant_ptr participant)
+  {
+    participants_.insert(participant);
+    std::for_each(recent_msgs_.begin(), recent_msgs_.end(),
+        boost::bind(&chat_participant::deliver,
+          participant, boost::placeholders::_1));
+  }
+
+  void leave(chat_participant_ptr participant)
+  {
+    participants_.erase(participant);
+  }
+
+  void deliver(const chat_message& msg)
+  {
+    recent_msgs_.push_back(msg);
+    while (recent_msgs_.size() > max_recent_msgs)
+      recent_msgs_.pop_front();
+
+    std::for_each(participants_.begin(), participants_.end(),
+        boost::bind(&chat_participant::deliver,
+          boost::placeholders::_1, boost::ref(msg)));
+  }
+
+private:
+  std::set<chat_participant_ptr> participants_;
+  enum { max_recent_msgs = 100 };
+  chat_message_queue recent_msgs_;
+};
+
+//----------------------------------------------------------------------
+
+class chat_session
+  : public chat_participant,
+    public boost::enable_shared_from_this<chat_session>
+{
+public:
+  chat_session(boost::asio::io_context& io_context, chat_room& room)
+    : socket_(io_context),
+      room_(room)
+  {
+  }
+
+  tcp::socket& socket()
+  {
+    return socket_;
+  }
+
+  void start()
+  {
+    room_.join(shared_from_this());
+    boost::asio::async_read(socket_,
+        boost::asio::buffer(read_msg_.data(), chat_message::header_length),
+        boost::bind(
+          &chat_session::handle_read_header, shared_from_this(),
+          boost::asio::placeholders::error));
+  }
+
+  void deliver(const chat_message& msg)
+  {
+    bool write_in_progress = !write_msgs_.empty();
+    write_msgs_.push_back(msg);
+    if (!write_in_progress)
+    {
+      boost::asio::async_write(socket_,
+          boost::asio::buffer(write_msgs_.front().data(),
+            write_msgs_.front().length()),
+          boost::bind(&chat_session::handle_write, shared_from_this(),
+            boost::asio::placeholders::error));
+    }
+  }
+
+  void handle_read_header(const boost::system::error_code& error)
+  {
+    if (!error && read_msg_.decode_header())
+    {
+      boost::asio::async_read(socket_,
+          boost::asio::buffer(read_msg_.body(), read_msg_.body_length()),
+          boost::bind(&chat_session::handle_read_body, shared_from_this(),
+            boost::asio::placeholders::error));
+    }
+    else
+    {
+      room_.leave(shared_from_this());
+    }
+  }
+
+  void handle_read_body(const boost::system::error_code& error)
+  {
+    if (!error)
+    {
+      room_.deliver(read_msg_);
+      boost::asio::async_read(socket_,
+          boost::asio::buffer(read_msg_.data(), chat_message::header_length),
+          boost::bind(&chat_session::handle_read_header, shared_from_this(),
+            boost::asio::placeholders::error));
+    }
+    else
+    {
+      room_.leave(shared_from_this());
+    }
+  }
+
+  void handle_write(const boost::system::error_code& error)
+  {
+    if (!error)
+    {
+      write_msgs_.pop_front();
+      if (!write_msgs_.empty())
+      {
+        boost::asio::async_write(socket_,
+            boost::asio::buffer(write_msgs_.front().data(),
+              write_msgs_.front().length()),
+            boost::bind(&chat_session::handle_write, shared_from_this(),
+              boost::asio::placeholders::error));
+      }
+    }
+    else
+    {
+      room_.leave(shared_from_this());
+    }
+  }
+
+private:
+  tcp::socket socket_;
+  chat_room& room_;
+  chat_message read_msg_;
+  chat_message_queue write_msgs_;
+};
+
+typedef boost::shared_ptr<chat_session> chat_session_ptr;
+
+//----------------------------------------------------------------------
+
+class chat_server
+{
+public:
+  chat_server(boost::asio::io_context& io_context,
+      const tcp::endpoint& endpoint)
+    : io_context_(io_context),
+      acceptor_(io_context, endpoint)
+  {
+    start_accept();
+  }
+
+  void start_accept()
+  {
+    chat_session_ptr new_session(new chat_session(io_context_, room_));
+    acceptor_.async_accept(new_session->socket(),
+        boost::bind(&chat_server::handle_accept, this, new_session,
+          boost::asio::placeholders::error));
+  }
+
+  void handle_accept(chat_session_ptr session,
+      const boost::system::error_code& error)
+  {
+    if (!error)
+    {
+      session->start();
+    }
+
+    start_accept();
+  }
+
+private:
+  boost::asio::io_context& io_context_;
+  tcp::acceptor acceptor_;
+  chat_room room_;
+};
+
+typedef boost::shared_ptr<chat_server> chat_server_ptr;
+typedef std::list<chat_server_ptr> chat_server_list;
+
+//----------------------------------------------------------------------
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    if (argc < 2)
+    {
+      std::cerr << "Usage: chat_server <port> [<port> ...]\n";
+      return 1;
+    }
+
+    boost::asio::io_context io_context;
+
+    chat_server_list servers;
+    for (int i = 1; i < argc; ++i)
+    {
+      using namespace std; // For atoi.
+      tcp::endpoint endpoint(tcp::v4(), atoi(argv[i]));
+      chat_server_ptr server(new chat_server(io_context, endpoint));
+      servers.push_back(server);
+    }
+
+    io_context.run();
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << "Exception: " << e.what() << "\n";
+  }
+
+  return 0;
+}

doc/html/boost_asio/example/cpp03/chat/posix_chat_client.cpp

@@ -0,0 +1,204 @@
+//
+// posix_chat_client.cpp
+// ~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <cstdlib>
+#include <cstring>
+#include <iostream>
+#include <boost/array.hpp>
+#include <boost/bind/bind.hpp>
+#include <boost/asio.hpp>
+#include "chat_message.hpp"
+
+#if defined(BOOST_ASIO_HAS_POSIX_STREAM_DESCRIPTOR)
+
+using boost::asio::ip::tcp;
+namespace posix = boost::asio::posix;
+
+class posix_chat_client
+{
+public:
+  posix_chat_client(boost::asio::io_context& io_context,
+      const tcp::resolver::results_type& endpoints)
+    : socket_(io_context),
+      input_(io_context, ::dup(STDIN_FILENO)),
+      output_(io_context, ::dup(STDOUT_FILENO)),
+      input_buffer_(chat_message::max_body_length)
+  {
+    boost::asio::async_connect(socket_, endpoints,
+        boost::bind(&posix_chat_client::handle_connect, this,
+          boost::asio::placeholders::error));
+  }
+
+private:
+
+  void handle_connect(const boost::system::error_code& error)
+  {
+    if (!error)
+    {
+      // Read the fixed-length header of the next message from the server.
+      boost::asio::async_read(socket_,
+          boost::asio::buffer(read_msg_.data(), chat_message::header_length),
+          boost::bind(&posix_chat_client::handle_read_header, this,
+            boost::asio::placeholders::error));
+
+      // Read a line of input entered by the user.
+      boost::asio::async_read_until(input_, input_buffer_, '\n',
+          boost::bind(&posix_chat_client::handle_read_input, this,
+            boost::asio::placeholders::error,
+            boost::asio::placeholders::bytes_transferred));
+    }
+  }
+
+  void handle_read_header(const boost::system::error_code& error)
+  {
+    if (!error && read_msg_.decode_header())
+    {
+      // Read the variable-length body of the message from the server.
+      boost::asio::async_read(socket_,
+          boost::asio::buffer(read_msg_.body(), read_msg_.body_length()),
+          boost::bind(&posix_chat_client::handle_read_body, this,
+            boost::asio::placeholders::error));
+    }
+    else
+    {
+      close();
+    }
+  }
+
+  void handle_read_body(const boost::system::error_code& error)
+  {
+    if (!error)
+    {
+      // Write out the message we just received, terminated by a newline.
+      static char eol[] = { '\n' };
+      boost::array<boost::asio::const_buffer, 2> buffers = {{
+        boost::asio::buffer(read_msg_.body(), read_msg_.body_length()),
+        boost::asio::buffer(eol) }};
+      boost::asio::async_write(output_, buffers,
+          boost::bind(&posix_chat_client::handle_write_output, this,
+            boost::asio::placeholders::error));
+    }
+    else
+    {
+      close();
+    }
+  }
+
+  void handle_write_output(const boost::system::error_code& error)
+  {
+    if (!error)
+    {
+      // Read the fixed-length header of the next message from the server.
+      boost::asio::async_read(socket_,
+          boost::asio::buffer(read_msg_.data(), chat_message::header_length),
+          boost::bind(&posix_chat_client::handle_read_header, this,
+            boost::asio::placeholders::error));
+    }
+    else
+    {
+      close();
+    }
+  }
+
+  void handle_read_input(const boost::system::error_code& error,
+      std::size_t length)
+  {
+    if (!error)
+    {
+      // Write the message (minus the newline) to the server.
+      write_msg_.body_length(length - 1);
+      input_buffer_.sgetn(write_msg_.body(), length - 1);
+      input_buffer_.consume(1); // Remove newline from input.
+      write_msg_.encode_header();
+      boost::asio::async_write(socket_,
+          boost::asio::buffer(write_msg_.data(), write_msg_.length()),
+          boost::bind(&posix_chat_client::handle_write, this,
+            boost::asio::placeholders::error));
+    }
+    else if (error == boost::asio::error::not_found)
+    {
+      // Didn't get a newline. Send whatever we have.
+      write_msg_.body_length(input_buffer_.size());
+      input_buffer_.sgetn(write_msg_.body(), input_buffer_.size());
+      write_msg_.encode_header();
+      boost::asio::async_write(socket_,
+          boost::asio::buffer(write_msg_.data(), write_msg_.length()),
+          boost::bind(&posix_chat_client::handle_write, this,
+            boost::asio::placeholders::error));
+    }
+    else
+    {
+      close();
+    }
+  }
+
+  void handle_write(const boost::system::error_code& error)
+  {
+    if (!error)
+    {
+      // Read a line of input entered by the user.
+      boost::asio::async_read_until(input_, input_buffer_, '\n',
+          boost::bind(&posix_chat_client::handle_read_input, this,
+            boost::asio::placeholders::error,
+            boost::asio::placeholders::bytes_transferred));
+    }
+    else
+    {
+      close();
+    }
+  }
+
+  void close()
+  {
+    // Cancel all outstanding asynchronous operations.
+    socket_.close();
+    input_.close();
+    output_.close();
+  }
+
+private:
+  tcp::socket socket_;
+  posix::stream_descriptor input_;
+  posix::stream_descriptor output_;
+  chat_message read_msg_;
+  chat_message write_msg_;
+  boost::asio::streambuf input_buffer_;
+};
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    if (argc != 3)
+    {
+      std::cerr << "Usage: posix_chat_client <host> <port>\n";
+      return 1;
+    }
+
+    boost::asio::io_context io_context;
+
+    tcp::resolver resolver(io_context);
+    tcp::resolver::results_type endpoints = resolver.resolve(argv[1], argv[2]);
+
+    posix_chat_client c(io_context, endpoints);
+
+    io_context.run();
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << "Exception: " << e.what() << "\n";
+  }
+
+  return 0;
+}
+
+#else // defined(BOOST_ASIO_HAS_POSIX_STREAM_DESCRIPTOR)
+int main() {}
+#endif // defined(BOOST_ASIO_HAS_POSIX_STREAM_DESCRIPTOR)

doc/html/boost_asio/example/cpp03/echo/async_tcp_echo_server.cpp

@@ -0,0 +1,137 @@
+//
+// async_tcp_echo_server.cpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <cstdlib>
+#include <iostream>
+#include <boost/bind/bind.hpp>
+#include <boost/asio.hpp>
+
+using boost::asio::ip::tcp;
+
+class session
+{
+public:
+  session(boost::asio::io_context& io_context)
+    : socket_(io_context)
+  {
+  }
+
+  tcp::socket& socket()
+  {
+    return socket_;
+  }
+
+  void start()
+  {
+    socket_.async_read_some(boost::asio::buffer(data_, max_length),
+        boost::bind(&session::handle_read, this,
+          boost::asio::placeholders::error,
+          boost::asio::placeholders::bytes_transferred));
+  }
+
+private:
+  void handle_read(const boost::system::error_code& error,
+      size_t bytes_transferred)
+  {
+    if (!error)
+    {
+      boost::asio::async_write(socket_,
+          boost::asio::buffer(data_, bytes_transferred),
+          boost::bind(&session::handle_write, this,
+            boost::asio::placeholders::error));
+    }
+    else
+    {
+      delete this;
+    }
+  }
+
+  void handle_write(const boost::system::error_code& error)
+  {
+    if (!error)
+    {
+      socket_.async_read_some(boost::asio::buffer(data_, max_length),
+          boost::bind(&session::handle_read, this,
+            boost::asio::placeholders::error,
+            boost::asio::placeholders::bytes_transferred));
+    }
+    else
+    {
+      delete this;
+    }
+  }
+
+  tcp::socket socket_;
+  enum { max_length = 1024 };
+  char data_[max_length];
+};
+
+class server
+{
+public:
+  server(boost::asio::io_context& io_context, short port)
+    : io_context_(io_context),
+      acceptor_(io_context, tcp::endpoint(tcp::v4(), port))
+  {
+    start_accept();
+  }
+
+private:
+  void start_accept()
+  {
+    session* new_session = new session(io_context_);
+    acceptor_.async_accept(new_session->socket(),
+        boost::bind(&server::handle_accept, this, new_session,
+          boost::asio::placeholders::error));
+  }
+
+  void handle_accept(session* new_session,
+      const boost::system::error_code& error)
+  {
+    if (!error)
+    {
+      new_session->start();
+    }
+    else
+    {
+      delete new_session;
+    }
+
+    start_accept();
+  }
+
+  boost::asio::io_context& io_context_;
+  tcp::acceptor acceptor_;
+};
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    if (argc != 2)
+    {
+      std::cerr << "Usage: async_tcp_echo_server <port>\n";
+      return 1;
+    }
+
+    boost::asio::io_context io_context;
+
+    using namespace std; // For atoi.
+    server s(io_context, atoi(argv[1]));
+
+    io_context.run();
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << "Exception: " << e.what() << "\n";
+  }
+
+  return 0;
+}

doc/html/boost_asio/example/cpp03/echo/async_udp_echo_server.cpp

@@ -0,0 +1,92 @@
+//
+// async_udp_echo_server.cpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <cstdlib>
+#include <iostream>
+#include <boost/bind/bind.hpp>
+#include <boost/asio.hpp>
+
+using boost::asio::ip::udp;
+
+class server
+{
+public:
+  server(boost::asio::io_context& io_context, short port)
+    : socket_(io_context, udp::endpoint(udp::v4(), port))
+  {
+    socket_.async_receive_from(
+        boost::asio::buffer(data_, max_length), sender_endpoint_,
+        boost::bind(&server::handle_receive_from, this,
+          boost::asio::placeholders::error,
+          boost::asio::placeholders::bytes_transferred));
+  }
+
+  void handle_receive_from(const boost::system::error_code& error,
+      size_t bytes_recvd)
+  {
+    if (!error && bytes_recvd > 0)
+    {
+      socket_.async_send_to(
+          boost::asio::buffer(data_, bytes_recvd), sender_endpoint_,
+          boost::bind(&server::handle_send_to, this,
+            boost::asio::placeholders::error,
+            boost::asio::placeholders::bytes_transferred));
+    }
+    else
+    {
+      socket_.async_receive_from(
+          boost::asio::buffer(data_, max_length), sender_endpoint_,
+          boost::bind(&server::handle_receive_from, this,
+            boost::asio::placeholders::error,
+            boost::asio::placeholders::bytes_transferred));
+    }
+  }
+
+  void handle_send_to(const boost::system::error_code& /*error*/,
+      size_t /*bytes_sent*/)
+  {
+    socket_.async_receive_from(
+        boost::asio::buffer(data_, max_length), sender_endpoint_,
+        boost::bind(&server::handle_receive_from, this,
+          boost::asio::placeholders::error,
+          boost::asio::placeholders::bytes_transferred));
+  }
+
+private:
+  udp::socket socket_;
+  udp::endpoint sender_endpoint_;
+  enum { max_length = 1024 };
+  char data_[max_length];
+};
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    if (argc != 2)
+    {
+      std::cerr << "Usage: async_udp_echo_server <port>\n";
+      return 1;
+    }
+
+    boost::asio::io_context io_context;
+
+    using namespace std; // For atoi.
+    server s(io_context, atoi(argv[1]));
+
+    io_context.run();
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << "Exception: " << e.what() << "\n";
+  }
+
+  return 0;
+}

doc/html/boost_asio/example/cpp03/echo/blocking_tcp_echo_client.cpp

@@ -0,0 +1,59 @@
+//
+// blocking_tcp_echo_client.cpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <cstdlib>
+#include <cstring>
+#include <iostream>
+#include <boost/asio.hpp>
+
+using boost::asio::ip::tcp;
+
+enum { max_length = 1024 };
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    if (argc != 3)
+    {
+      std::cerr << "Usage: blocking_tcp_echo_client <host> <port>\n";
+      return 1;
+    }
+
+    boost::asio::io_context io_context;
+
+    tcp::resolver resolver(io_context);
+    tcp::resolver::results_type endpoints =
+      resolver.resolve(tcp::v4(), argv[1], argv[2]);
+
+    tcp::socket s(io_context);
+    boost::asio::connect(s, endpoints);
+
+    using namespace std; // For strlen.
+    std::cout << "Enter message: ";
+    char request[max_length];
+    std::cin.getline(request, max_length);
+    size_t request_length = strlen(request);
+    boost::asio::write(s, boost::asio::buffer(request, request_length));
+
+    char reply[max_length];
+    size_t reply_length = boost::asio::read(s,
+        boost::asio::buffer(reply, request_length));
+    std::cout << "Reply is: ";
+    std::cout.write(reply, reply_length);
+    std::cout << "\n";
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << "Exception: " << e.what() << "\n";
+  }
+
+  return 0;
+}

doc/html/boost_asio/example/cpp03/echo/blocking_tcp_echo_server.cpp

@@ -0,0 +1,80 @@
+//
+// blocking_tcp_echo_server.cpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <cstdlib>
+#include <iostream>
+#include <boost/bind/bind.hpp>
+#include <boost/smart_ptr.hpp>
+#include <boost/asio.hpp>
+#include <boost/thread/thread.hpp>
+
+using boost::asio::ip::tcp;
+
+const int max_length = 1024;
+
+typedef boost::shared_ptr<tcp::socket> socket_ptr;
+
+void session(socket_ptr sock)
+{
+  try
+  {
+    for (;;)
+    {
+      char data[max_length];
+
+      boost::system::error_code error;
+      size_t length = sock->read_some(boost::asio::buffer(data), error);
+      if (error == boost::asio::error::eof)
+        break; // Connection closed cleanly by peer.
+      else if (error)
+        throw boost::system::system_error(error); // Some other error.
+
+      boost::asio::write(*sock, boost::asio::buffer(data, length));
+    }
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << "Exception in thread: " << e.what() << "\n";
+  }
+}
+
+void server(boost::asio::io_context& io_context, unsigned short port)
+{
+  tcp::acceptor a(io_context, tcp::endpoint(tcp::v4(), port));
+  for (;;)
+  {
+    socket_ptr sock(new tcp::socket(io_context));
+    a.accept(*sock);
+    boost::thread t(boost::bind(session, sock));
+  }
+}
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    if (argc != 2)
+    {
+      std::cerr << "Usage: blocking_tcp_echo_server <port>\n";
+      return 1;
+    }
+
+    boost::asio::io_context io_context;
+
+    using namespace std; // For atoi.
+    server(io_context, atoi(argv[1]));
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << "Exception: " << e.what() << "\n";
+  }
+
+  return 0;
+}

doc/html/boost_asio/example/cpp03/echo/blocking_udp_echo_client.cpp

@@ -0,0 +1,59 @@
+//
+// blocking_udp_echo_client.cpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <cstdlib>
+#include <cstring>
+#include <iostream>
+#include <boost/asio.hpp>
+
+using boost::asio::ip::udp;
+
+enum { max_length = 1024 };
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    if (argc != 3)
+    {
+      std::cerr << "Usage: blocking_udp_echo_client <host> <port>\n";
+      return 1;
+    }
+
+    boost::asio::io_context io_context;
+
+    udp::socket s(io_context, udp::endpoint(udp::v4(), 0));
+
+    udp::resolver resolver(io_context);
+    udp::resolver::results_type endpoints =
+      resolver.resolve(udp::v4(), argv[1], argv[2]);
+
+    using namespace std; // For strlen.
+    std::cout << "Enter message: ";
+    char request[max_length];
+    std::cin.getline(request, max_length);
+    size_t request_length = strlen(request);
+    s.send_to(boost::asio::buffer(request, request_length), *endpoints.begin());
+
+    char reply[max_length];
+    udp::endpoint sender_endpoint;
+    size_t reply_length = s.receive_from(
+        boost::asio::buffer(reply, max_length), sender_endpoint);
+    std::cout << "Reply is: ";
+    std::cout.write(reply, reply_length);
+    std::cout << "\n";
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << "Exception: " << e.what() << "\n";
+  }
+
+  return 0;
+}

doc/html/boost_asio/example/cpp03/echo/blocking_udp_echo_server.cpp

@@ -0,0 +1,53 @@
+//
+// blocking_udp_echo_server.cpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <cstdlib>
+#include <iostream>
+#include <boost/asio.hpp>
+
+using boost::asio::ip::udp;
+
+enum { max_length = 1024 };
+
+void server(boost::asio::io_context& io_context, unsigned short port)
+{
+  udp::socket sock(io_context, udp::endpoint(udp::v4(), port));
+  for (;;)
+  {
+    char data[max_length];
+    udp::endpoint sender_endpoint;
+    size_t length = sock.receive_from(
+        boost::asio::buffer(data, max_length), sender_endpoint);
+    sock.send_to(boost::asio::buffer(data, length), sender_endpoint);
+  }
+}
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    if (argc != 2)
+    {
+      std::cerr << "Usage: blocking_udp_echo_server <port>\n";
+      return 1;
+    }
+
+    boost::asio::io_context io_context;
+
+    using namespace std; // For atoi.
+    server(io_context, atoi(argv[1]));
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << "Exception: " << e.what() << "\n";
+  }
+
+  return 0;
+}

doc/html/boost_asio/example/cpp03/fork/daemon.cpp

@@ -0,0 +1,190 @@
+//
+// daemon.cpp
+// ~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <boost/asio/io_context.hpp>
+#include <boost/asio/ip/udp.hpp>
+#include <boost/asio/signal_set.hpp>
+#include <boost/array.hpp>
+#include <boost/bind/bind.hpp>
+#include <ctime>
+#include <iostream>
+#include <syslog.h>
+#include <unistd.h>
+
+using boost::asio::ip::udp;
+
+class udp_daytime_server
+{
+public:
+  udp_daytime_server(boost::asio::io_context& io_context)
+    : socket_(io_context, udp::endpoint(udp::v4(), 13))
+  {
+    start_receive();
+  }
+
+private:
+  void start_receive()
+  {
+    socket_.async_receive_from(
+        boost::asio::buffer(recv_buffer_), remote_endpoint_,
+        boost::bind(&udp_daytime_server::handle_receive,
+          this, boost::placeholders::_1));
+  }
+
+  void handle_receive(const boost::system::error_code& ec)
+  {
+    if (!ec)
+    {
+      using namespace std; // For time_t, time and ctime;
+      time_t now = time(0);
+      std::string message = ctime(&now);
+
+      boost::system::error_code ignored_ec;
+      socket_.send_to(boost::asio::buffer(message),
+          remote_endpoint_, 0, ignored_ec);
+    }
+
+    start_receive();
+  }
+
+  udp::socket socket_;
+  udp::endpoint remote_endpoint_;
+  boost::array<char, 1> recv_buffer_;
+};
+
+int main()
+{
+  try
+  {
+    boost::asio::io_context io_context;
+
+    // Initialise the server before becoming a daemon. If the process is
+    // started from a shell, this means any errors will be reported back to the
+    // user.
+    udp_daytime_server server(io_context);
+
+    // Register signal handlers so that the daemon may be shut down. You may
+    // also want to register for other signals, such as SIGHUP to trigger a
+    // re-read of a configuration file.
+    boost::asio::signal_set signals(io_context, SIGINT, SIGTERM);
+    signals.async_wait(
+        boost::bind(&boost::asio::io_context::stop, &io_context));
+
+    // Inform the io_context that we are about to become a daemon. The
+    // io_context cleans up any internal resources, such as threads, that may
+    // interfere with forking.
+    io_context.notify_fork(boost::asio::io_context::fork_prepare);
+
+    // Fork the process and have the parent exit. If the process was started
+    // from a shell, this returns control to the user. Forking a new process is
+    // also a prerequisite for the subsequent call to setsid().
+    if (pid_t pid = fork())
+    {
+      if (pid > 0)
+      {
+        // We're in the parent process and need to exit.
+        //
+        // When the exit() function is used, the program terminates without
+        // invoking local variables' destructors. Only global variables are
+        // destroyed. As the io_context object is a local variable, this means
+        // we do not have to call:
+        //
+        //   io_context.notify_fork(boost::asio::io_context::fork_parent);
+        //
+        // However, this line should be added before each call to exit() if
+        // using a global io_context object. An additional call:
+        //
+        //   io_context.notify_fork(boost::asio::io_context::fork_prepare);
+        //
+        // should also precede the second fork().
+        exit(0);
+      }
+      else
+      {
+        syslog(LOG_ERR | LOG_USER, "First fork failed: %m");
+        return 1;
+      }
+    }
+
+    // Make the process a new session leader. This detaches it from the
+    // terminal.
+    setsid();
+
+    // A process inherits its working directory from its parent. This could be
+    // on a mounted filesystem, which means that the running daemon would
+    // prevent this filesystem from being unmounted. Changing to the root
+    // directory avoids this problem.
+    chdir("/");
+
+    // The file mode creation mask is also inherited from the parent process.
+    // We don't want to restrict the permissions on files created by the
+    // daemon, so the mask is cleared.
+    umask(0);
+
+    // A second fork ensures the process cannot acquire a controlling terminal.
+    if (pid_t pid = fork())
+    {
+      if (pid > 0)
+      {
+        exit(0);
+      }
+      else
+      {
+        syslog(LOG_ERR | LOG_USER, "Second fork failed: %m");
+        return 1;
+      }
+    }
+
+    // Close the standard streams. This decouples the daemon from the terminal
+    // that started it.
+    close(0);
+    close(1);
+    close(2);
+
+    // We don't want the daemon to have any standard input.
+    if (open("/dev/null", O_RDONLY) < 0)
+    {
+      syslog(LOG_ERR | LOG_USER, "Unable to open /dev/null: %m");
+      return 1;
+    }
+
+    // Send standard output to a log file.
+    const char* output = "/tmp/asio.daemon.out";
+    const int flags = O_WRONLY | O_CREAT | O_APPEND;
+    const mode_t mode = S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH;
+    if (open(output, flags, mode) < 0)
+    {
+      syslog(LOG_ERR | LOG_USER, "Unable to open output file %s: %m", output);
+      return 1;
+    }
+
+    // Also send standard error to the same log file.
+    if (dup(1) < 0)
+    {
+      syslog(LOG_ERR | LOG_USER, "Unable to dup output descriptor: %m");
+      return 1;
+    }
+
+    // Inform the io_context that we have finished becoming a daemon. The
+    // io_context uses this opportunity to create any internal file descriptors
+    // that need to be private to the new process.
+    io_context.notify_fork(boost::asio::io_context::fork_child);
+
+    // The io_context can now be used normally.
+    syslog(LOG_INFO | LOG_USER, "Daemon started");
+    io_context.run();
+    syslog(LOG_INFO | LOG_USER, "Daemon stopped");
+  }
+  catch (std::exception& e)
+  {
+    syslog(LOG_ERR | LOG_USER, "Exception: %s", e.what());
+    std::cerr << "Exception: " << e.what() << std::endl;
+  }
+}

doc/html/boost_asio/example/cpp03/fork/process_per_connection.cpp

@@ -0,0 +1,161 @@
+//
+// process_per_connection.cpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <boost/asio/io_context.hpp>
+#include <boost/asio/ip/tcp.hpp>
+#include <boost/asio/signal_set.hpp>
+#include <boost/asio/write.hpp>
+#include <boost/array.hpp>
+#include <boost/bind/bind.hpp>
+#include <cstdlib>
+#include <iostream>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+using boost::asio::ip::tcp;
+
+class server
+{
+public:
+  server(boost::asio::io_context& io_context, unsigned short port)
+    : io_context_(io_context),
+      signal_(io_context, SIGCHLD),
+      acceptor_(io_context, tcp::endpoint(tcp::v4(), port)),
+      socket_(io_context)
+  {
+    start_signal_wait();
+    start_accept();
+  }
+
+private:
+  void start_signal_wait()
+  {
+    signal_.async_wait(boost::bind(&server::handle_signal_wait, this));
+  }
+
+  void handle_signal_wait()
+  {
+    // Only the parent process should check for this signal. We can determine
+    // whether we are in the parent by checking if the acceptor is still open.
+    if (acceptor_.is_open())
+    {
+      // Reap completed child processes so that we don't end up with zombies.
+      int status = 0;
+      while (waitpid(-1, &status, WNOHANG) > 0) {}
+
+      start_signal_wait();
+    }
+  }
+
+  void start_accept()
+  {
+    acceptor_.async_accept(socket_,
+        boost::bind(&server::handle_accept, this, boost::placeholders::_1));
+  }
+
+  void handle_accept(const boost::system::error_code& ec)
+  {
+    if (!ec)
+    {
+      // Inform the io_context that we are about to fork. The io_context cleans
+      // up any internal resources, such as threads, that may interfere with
+      // forking.
+      io_context_.notify_fork(boost::asio::io_context::fork_prepare);
+
+      if (fork() == 0)
+      {
+        // Inform the io_context that the fork is finished and that this is the
+        // child process. The io_context uses this opportunity to create any
+        // internal file descriptors that must be private to the new process.
+        io_context_.notify_fork(boost::asio::io_context::fork_child);
+
+        // The child won't be accepting new connections, so we can close the
+        // acceptor. It remains open in the parent.
+        acceptor_.close();
+
+        // The child process is not interested in processing the SIGCHLD signal.
+        signal_.cancel();
+
+        start_read();
+      }
+      else
+      {
+        // Inform the io_context that the fork is finished (or failed) and that
+        // this is the parent process. The io_context uses this opportunity to
+        // recreate any internal resources that were cleaned up during
+        // preparation for the fork.
+        io_context_.notify_fork(boost::asio::io_context::fork_parent);
+
+        socket_.close();
+        start_accept();
+      }
+    }
+    else
+    {
+      std::cerr << "Accept error: " << ec.message() << std::endl;
+      start_accept();
+    }
+  }
+
+  void start_read()
+  {
+    socket_.async_read_some(boost::asio::buffer(data_),
+        boost::bind(&server::handle_read, this,
+          boost::placeholders::_1, boost::placeholders::_2));
+  }
+
+  void handle_read(const boost::system::error_code& ec, std::size_t length)
+  {
+    if (!ec)
+      start_write(length);
+  }
+
+  void start_write(std::size_t length)
+  {
+    boost::asio::async_write(socket_, boost::asio::buffer(data_, length),
+        boost::bind(&server::handle_write, this, boost::placeholders::_1));
+  }
+
+  void handle_write(const boost::system::error_code& ec)
+  {
+    if (!ec)
+      start_read();
+  }
+
+  boost::asio::io_context& io_context_;
+  boost::asio::signal_set signal_;
+  tcp::acceptor acceptor_;
+  tcp::socket socket_;
+  boost::array<char, 1024> data_;
+};
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    if (argc != 2)
+    {
+      std::cerr << "Usage: process_per_connection <port>\n";
+      return 1;
+    }
+
+    boost::asio::io_context io_context;
+
+    using namespace std; // For atoi.
+    server s(io_context, atoi(argv[1]));
+
+    io_context.run();
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << "Exception: " << e.what() << std::endl;
+  }
+}

doc/html/boost_asio/example/cpp03/http/client/async_client.cpp

@@ -0,0 +1,204 @@
+//
+// async_client.cpp
+// ~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <iostream>
+#include <istream>
+#include <ostream>
+#include <string>
+#include <boost/asio.hpp>
+#include <boost/bind/bind.hpp>
+
+using boost::asio::ip::tcp;
+
+class client
+{
+public:
+  client(boost::asio::io_context& io_context,
+      const std::string& server, const std::string& path)
+    : resolver_(io_context),
+      socket_(io_context)
+  {
+    // Form the request. We specify the "Connection: close" header so that the
+    // server will close the socket after transmitting the response. This will
+    // allow us to treat all data up until the EOF as the content.
+    std::ostream request_stream(&request_);
+    request_stream << "GET " << path << " HTTP/1.0\r\n";
+    request_stream << "Host: " << server << "\r\n";
+    request_stream << "Accept: */*\r\n";
+    request_stream << "Connection: close\r\n\r\n";
+
+    // Start an asynchronous resolve to translate the server and service names
+    // into a list of endpoints.
+    resolver_.async_resolve(server, "http",
+        boost::bind(&client::handle_resolve, this,
+          boost::asio::placeholders::error,
+          boost::asio::placeholders::results));
+  }
+
+private:
+  void handle_resolve(const boost::system::error_code& err,
+      const tcp::resolver::results_type& endpoints)
+  {
+    if (!err)
+    {
+      // Attempt a connection to each endpoint in the list until we
+      // successfully establish a connection.
+      boost::asio::async_connect(socket_, endpoints,
+          boost::bind(&client::handle_connect, this,
+            boost::asio::placeholders::error));
+    }
+    else
+    {
+      std::cout << "Error: " << err.message() << "\n";
+    }
+  }
+
+  void handle_connect(const boost::system::error_code& err)
+  {
+    if (!err)
+    {
+      // The connection was successful. Send the request.
+      boost::asio::async_write(socket_, request_,
+          boost::bind(&client::handle_write_request, this,
+            boost::asio::placeholders::error));
+    }
+    else
+    {
+      std::cout << "Error: " << err.message() << "\n";
+    }
+  }
+
+  void handle_write_request(const boost::system::error_code& err)
+  {
+    if (!err)
+    {
+      // Read the response status line. The response_ streambuf will
+      // automatically grow to accommodate the entire line. The growth may be
+      // limited by passing a maximum size to the streambuf constructor.
+      boost::asio::async_read_until(socket_, response_, "\r\n",
+          boost::bind(&client::handle_read_status_line, this,
+            boost::asio::placeholders::error));
+    }
+    else
+    {
+      std::cout << "Error: " << err.message() << "\n";
+    }
+  }
+
+  void handle_read_status_line(const boost::system::error_code& err)
+  {
+    if (!err)
+    {
+      // Check that response is OK.
+      std::istream response_stream(&response_);
+      std::string http_version;
+      response_stream >> http_version;
+      unsigned int status_code;
+      response_stream >> status_code;
+      std::string status_message;
+      std::getline(response_stream, status_message);
+      if (!response_stream || http_version.substr(0, 5) != "HTTP/")
+      {
+        std::cout << "Invalid response\n";
+        return;
+      }
+      if (status_code != 200)
+      {
+        std::cout << "Response returned with status code ";
+        std::cout << status_code << "\n";
+        return;
+      }
+
+      // Read the response headers, which are terminated by a blank line.
+      boost::asio::async_read_until(socket_, response_, "\r\n\r\n",
+          boost::bind(&client::handle_read_headers, this,
+            boost::asio::placeholders::error));
+    }
+    else
+    {
+      std::cout << "Error: " << err << "\n";
+    }
+  }
+
+  void handle_read_headers(const boost::system::error_code& err)
+  {
+    if (!err)
+    {
+      // Process the response headers.
+      std::istream response_stream(&response_);
+      std::string header;
+      while (std::getline(response_stream, header) && header != "\r")
+        std::cout << header << "\n";
+      std::cout << "\n";
+
+      // Write whatever content we already have to output.
+      if (response_.size() > 0)
+        std::cout << &response_;
+
+      // Start reading remaining data until EOF.
+      boost::asio::async_read(socket_, response_,
+          boost::asio::transfer_at_least(1),
+          boost::bind(&client::handle_read_content, this,
+            boost::asio::placeholders::error));
+    }
+    else
+    {
+      std::cout << "Error: " << err << "\n";
+    }
+  }
+
+  void handle_read_content(const boost::system::error_code& err)
+  {
+    if (!err)
+    {
+      // Write all of the data that has been read so far.
+      std::cout << &response_;
+
+      // Continue reading remaining data until EOF.
+      boost::asio::async_read(socket_, response_,
+          boost::asio::transfer_at_least(1),
+          boost::bind(&client::handle_read_content, this,
+            boost::asio::placeholders::error));
+    }
+    else if (err != boost::asio::error::eof)
+    {
+      std::cout << "Error: " << err << "\n";
+    }
+  }
+
+  tcp::resolver resolver_;
+  tcp::socket socket_;
+  boost::asio::streambuf request_;
+  boost::asio::streambuf response_;
+};
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    if (argc != 3)
+    {
+      std::cout << "Usage: async_client <server> <path>\n";
+      std::cout << "Example:\n";
+      std::cout << "  async_client www.boost.org /LICENSE_1_0.txt\n";
+      return 1;
+    }
+
+    boost::asio::io_context io_context;
+    client c(io_context, argv[1], argv[2]);
+    io_context.run();
+  }
+  catch (std::exception& e)
+  {
+    std::cout << "Exception: " << e.what() << "\n";
+  }
+
+  return 0;
+}

doc/html/boost_asio/example/cpp03/http/client/sync_client.cpp

@@ -0,0 +1,106 @@
+//
+// sync_client.cpp
+// ~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <iostream>
+#include <istream>
+#include <ostream>
+#include <string>
+#include <boost/asio.hpp>
+
+using boost::asio::ip::tcp;
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    if (argc != 3)
+    {
+      std::cout << "Usage: sync_client <server> <path>\n";
+      std::cout << "Example:\n";
+      std::cout << "  sync_client www.boost.org /LICENSE_1_0.txt\n";
+      return 1;
+    }
+
+    boost::asio::io_context io_context;
+
+    // Get a list of endpoints corresponding to the server name.
+    tcp::resolver resolver(io_context);
+    tcp::resolver::results_type endpoints = resolver.resolve(argv[1], "http");
+
+    // Try each endpoint until we successfully establish a connection.
+    tcp::socket socket(io_context);
+    boost::asio::connect(socket, endpoints);
+
+    // Form the request. We specify the "Connection: close" header so that the
+    // server will close the socket after transmitting the response. This will
+    // allow us to treat all data up until the EOF as the content.
+    boost::asio::streambuf request;
+    std::ostream request_stream(&request);
+    request_stream << "GET " << argv[2] << " HTTP/1.0\r\n";
+    request_stream << "Host: " << argv[1] << "\r\n";
+    request_stream << "Accept: */*\r\n";
+    request_stream << "Connection: close\r\n\r\n";
+
+    // Send the request.
+    boost::asio::write(socket, request);
+
+    // Read the response status line. The response streambuf will automatically
+    // grow to accommodate the entire line. The growth may be limited by passing
+    // a maximum size to the streambuf constructor.
+    boost::asio::streambuf response;
+    boost::asio::read_until(socket, response, "\r\n");
+
+    // Check that response is OK.
+    std::istream response_stream(&response);
+    std::string http_version;
+    response_stream >> http_version;
+    unsigned int status_code;
+    response_stream >> status_code;
+    std::string status_message;
+    std::getline(response_stream, status_message);
+    if (!response_stream || http_version.substr(0, 5) != "HTTP/")
+    {
+      std::cout << "Invalid response\n";
+      return 1;
+    }
+    if (status_code != 200)
+    {
+      std::cout << "Response returned with status code " << status_code << "\n";
+      return 1;
+    }
+
+    // Read the response headers, which are terminated by a blank line.
+    boost::asio::read_until(socket, response, "\r\n\r\n");
+
+    // Process the response headers.
+    std::string header;
+    while (std::getline(response_stream, header) && header != "\r")
+      std::cout << header << "\n";
+    std::cout << "\n";
+
+    // Write whatever content we already have to output.
+    if (response.size() > 0)
+      std::cout << &response;
+
+    // Read until EOF, writing data to output as we go.
+    boost::system::error_code error;
+    while (boost::asio::read(socket, response,
+          boost::asio::transfer_at_least(1), error))
+      std::cout << &response;
+    if (error != boost::asio::error::eof)
+      throw boost::system::system_error(error);
+  }
+  catch (std::exception& e)
+  {
+    std::cout << "Exception: " << e.what() << "\n";
+  }
+
+  return 0;
+}

doc/html/boost_asio/example/cpp03/http/server/connection.cpp

@@ -0,0 +1,99 @@
+//
+// connection.cpp
+// ~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include "connection.hpp"
+#include <vector>
+#include <boost/bind/bind.hpp>
+#include "connection_manager.hpp"
+#include "request_handler.hpp"
+
+namespace http {
+namespace server {
+
+connection::connection(boost::asio::io_context& io_context,
+    connection_manager& manager, request_handler& handler)
+  : socket_(io_context),
+    connection_manager_(manager),
+    request_handler_(handler)
+{
+}
+
+boost::asio::ip::tcp::socket& connection::socket()
+{
+  return socket_;
+}
+
+void connection::start()
+{
+  socket_.async_read_some(boost::asio::buffer(buffer_),
+      boost::bind(&connection::handle_read, shared_from_this(),
+        boost::asio::placeholders::error,
+        boost::asio::placeholders::bytes_transferred));
+}
+
+void connection::stop()
+{
+  socket_.close();
+}
+
+void connection::handle_read(const boost::system::error_code& e,
+    std::size_t bytes_transferred)
+{
+  if (!e)
+  {
+    boost::tribool result;
+    boost::tie(result, boost::tuples::ignore) = request_parser_.parse(
+        request_, buffer_.data(), buffer_.data() + bytes_transferred);
+
+    if (result)
+    {
+      request_handler_.handle_request(request_, reply_);
+      boost::asio::async_write(socket_, reply_.to_buffers(),
+          boost::bind(&connection::handle_write, shared_from_this(),
+            boost::asio::placeholders::error));
+    }
+    else if (!result)
+    {
+      reply_ = reply::stock_reply(reply::bad_request);
+      boost::asio::async_write(socket_, reply_.to_buffers(),
+          boost::bind(&connection::handle_write, shared_from_this(),
+            boost::asio::placeholders::error));
+    }
+    else
+    {
+      socket_.async_read_some(boost::asio::buffer(buffer_),
+          boost::bind(&connection::handle_read, shared_from_this(),
+            boost::asio::placeholders::error,
+            boost::asio::placeholders::bytes_transferred));
+    }
+  }
+  else if (e != boost::asio::error::operation_aborted)
+  {
+    connection_manager_.stop(shared_from_this());
+  }
+}
+
+void connection::handle_write(const boost::system::error_code& e)
+{
+  if (!e)
+  {
+    // Initiate graceful connection closure.
+    boost::system::error_code ignored_ec;
+    socket_.shutdown(boost::asio::ip::tcp::socket::shutdown_both, ignored_ec);
+  }
+
+  if (e != boost::asio::error::operation_aborted)
+  {
+    connection_manager_.stop(shared_from_this());
+  }
+}
+
+} // namespace server
+} // namespace http

doc/html/boost_asio/example/cpp03/http/server/connection.hpp

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+//
+// connection.hpp
+// ~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef HTTP_CONNECTION_HPP
+#define HTTP_CONNECTION_HPP
+
+#include <boost/asio.hpp>
+#include <boost/array.hpp>
+#include <boost/noncopyable.hpp>
+#include <boost/shared_ptr.hpp>
+#include <boost/enable_shared_from_this.hpp>
+#include "reply.hpp"
+#include "request.hpp"
+#include "request_handler.hpp"
+#include "request_parser.hpp"
+
+namespace http {
+namespace server {
+
+class connection_manager;
+
+/// Represents a single connection from a client.
+class connection
+  : public boost::enable_shared_from_this<connection>,
+    private boost::noncopyable
+{
+public:
+  /// Construct a connection with the given io_context.
+  explicit connection(boost::asio::io_context& io_context,
+      connection_manager& manager, request_handler& handler);
+
+  /// Get the socket associated with the connection.
+  boost::asio::ip::tcp::socket& socket();
+
+  /// Start the first asynchronous operation for the connection.
+  void start();
+
+  /// Stop all asynchronous operations associated with the connection.
+  void stop();
+
+private:
+  /// Handle completion of a read operation.
+  void handle_read(const boost::system::error_code& e,
+      std::size_t bytes_transferred);
+
+  /// Handle completion of a write operation.
+  void handle_write(const boost::system::error_code& e);
+
+  /// Socket for the connection.
+  boost::asio::ip::tcp::socket socket_;
+
+  /// The manager for this connection.
+  connection_manager& connection_manager_;
+
+  /// The handler used to process the incoming request.
+  request_handler& request_handler_;
+
+  /// Buffer for incoming data.
+  boost::array<char, 8192> buffer_;
+
+  /// The incoming request.
+  request request_;
+
+  /// The parser for the incoming request.
+  request_parser request_parser_;
+
+  /// The reply to be sent back to the client.
+  reply reply_;
+};
+
+typedef boost::shared_ptr<connection> connection_ptr;
+
+} // namespace server
+} // namespace http
+
+#endif // HTTP_CONNECTION_HPP

doc/html/boost_asio/example/cpp03/http/server/connection_manager.cpp

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+//
+// connection_manager.cpp
+// ~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include "connection_manager.hpp"
+#include <algorithm>
+#include <boost/bind/bind.hpp>
+
+namespace http {
+namespace server {
+
+void connection_manager::start(connection_ptr c)
+{
+  connections_.insert(c);
+  c->start();
+}
+
+void connection_manager::stop(connection_ptr c)
+{
+  connections_.erase(c);
+  c->stop();
+}
+
+void connection_manager::stop_all()
+{
+  std::for_each(connections_.begin(), connections_.end(),
+      boost::bind(&connection::stop, boost::placeholders::_1));
+  connections_.clear();
+}
+
+} // namespace server
+} // namespace http

doc/html/boost_asio/example/cpp03/http/server/connection_manager.hpp

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+//
+// connection_manager.hpp
+// ~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef HTTP_CONNECTION_MANAGER_HPP
+#define HTTP_CONNECTION_MANAGER_HPP
+
+#include <set>
+#include <boost/noncopyable.hpp>
+#include "connection.hpp"
+
+namespace http {
+namespace server {
+
+/// Manages open connections so that they may be cleanly stopped when the server
+/// needs to shut down.
+class connection_manager
+  : private boost::noncopyable
+{
+public:
+  /// Add the specified connection to the manager and start it.
+  void start(connection_ptr c);
+
+  /// Stop the specified connection.
+  void stop(connection_ptr c);
+
+  /// Stop all connections.
+  void stop_all();
+
+private:
+  /// The managed connections.
+  std::set<connection_ptr> connections_;
+};
+
+} // namespace server
+} // namespace http
+
+#endif // HTTP_CONNECTION_MANAGER_HPP

doc/html/boost_asio/example/cpp03/http/server/header.hpp

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+//
+// header.hpp
+// ~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef HTTP_HEADER_HPP
+#define HTTP_HEADER_HPP
+
+#include <string>
+
+namespace http {
+namespace server {
+
+struct header
+{
+  std::string name;
+  std::string value;
+};
+
+} // namespace server
+} // namespace http
+
+#endif // HTTP_HEADER_HPP

doc/html/boost_asio/example/cpp03/http/server/main.cpp

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+//
+// main.cpp
+// ~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <iostream>
+#include <string>
+#include <boost/asio.hpp>
+#include <boost/bind/bind.hpp>
+#include "server.hpp"
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    // Check command line arguments.
+    if (argc != 4)
+    {
+      std::cerr << "Usage: http_server <address> <port> <doc_root>\n";
+      std::cerr << "  For IPv4, try:\n";
+      std::cerr << "    receiver 0.0.0.0 80 .\n";
+      std::cerr << "  For IPv6, try:\n";
+      std::cerr << "    receiver 0::0 80 .\n";
+      return 1;
+    }
+
+    // Initialise the server.
+    http::server::server s(argv[1], argv[2], argv[3]);
+
+    // Run the server until stopped.
+    s.run();
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << "exception: " << e.what() << "\n";
+  }
+
+  return 0;
+}

doc/html/boost_asio/example/cpp03/http/server/mime_types.cpp

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+//
+// mime_types.cpp
+// ~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include "mime_types.hpp"
+
+namespace http {
+namespace server {
+namespace mime_types {
+
+struct mapping
+{
+  const char* extension;
+  const char* mime_type;
+} mappings[] =
+{
+  { "gif", "image/gif" },
+  { "htm", "text/html" },
+  { "html", "text/html" },
+  { "jpg", "image/jpeg" },
+  { "png", "image/png" },
+  { 0, 0 } // Marks end of list.
+};
+
+std::string extension_to_type(const std::string& extension)
+{
+  for (mapping* m = mappings; m->extension; ++m)
+  {
+    if (m->extension == extension)
+    {
+      return m->mime_type;
+    }
+  }
+
+  return "text/plain";
+}
+
+} // namespace mime_types
+} // namespace server
+} // namespace http

doc/html/boost_asio/example/cpp03/http/server/mime_types.hpp

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+//
+// mime_types.hpp
+// ~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef HTTP_MIME_TYPES_HPP
+#define HTTP_MIME_TYPES_HPP
+
+#include <string>
+
+namespace http {
+namespace server {
+namespace mime_types {
+
+/// Convert a file extension into a MIME type.
+std::string extension_to_type(const std::string& extension);
+
+} // namespace mime_types
+} // namespace server
+} // namespace http
+
+#endif // HTTP_MIME_TYPES_HPP

doc/html/boost_asio/example/cpp03/http/server/reply.cpp

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+//
+// reply.cpp
+// ~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include "reply.hpp"
+#include <string>
+#include <boost/lexical_cast.hpp>
+
+namespace http {
+namespace server {
+
+namespace status_strings {
+
+const std::string ok =
+  "HTTP/1.0 200 OK\r\n";
+const std::string created =
+  "HTTP/1.0 201 Created\r\n";
+const std::string accepted =
+  "HTTP/1.0 202 Accepted\r\n";
+const std::string no_content =
+  "HTTP/1.0 204 No Content\r\n";
+const std::string multiple_choices =
+  "HTTP/1.0 300 Multiple Choices\r\n";
+const std::string moved_permanently =
+  "HTTP/1.0 301 Moved Permanently\r\n";
+const std::string moved_temporarily =
+  "HTTP/1.0 302 Moved Temporarily\r\n";
+const std::string not_modified =
+  "HTTP/1.0 304 Not Modified\r\n";
+const std::string bad_request =
+  "HTTP/1.0 400 Bad Request\r\n";
+const std::string unauthorized =
+  "HTTP/1.0 401 Unauthorized\r\n";
+const std::string forbidden =
+  "HTTP/1.0 403 Forbidden\r\n";
+const std::string not_found =
+  "HTTP/1.0 404 Not Found\r\n";
+const std::string internal_server_error =
+  "HTTP/1.0 500 Internal Server Error\r\n";
+const std::string not_implemented =
+  "HTTP/1.0 501 Not Implemented\r\n";
+const std::string bad_gateway =
+  "HTTP/1.0 502 Bad Gateway\r\n";
+const std::string service_unavailable =
+  "HTTP/1.0 503 Service Unavailable\r\n";
+
+boost::asio::const_buffer to_buffer(reply::status_type status)
+{
+  switch (status)
+  {
+  case reply::ok:
+    return boost::asio::buffer(ok);
+  case reply::created:
+    return boost::asio::buffer(created);
+  case reply::accepted:
+    return boost::asio::buffer(accepted);
+  case reply::no_content:
+    return boost::asio::buffer(no_content);
+  case reply::multiple_choices:
+    return boost::asio::buffer(multiple_choices);
+  case reply::moved_permanently:
+    return boost::asio::buffer(moved_permanently);
+  case reply::moved_temporarily:
+    return boost::asio::buffer(moved_temporarily);
+  case reply::not_modified:
+    return boost::asio::buffer(not_modified);
+  case reply::bad_request:
+    return boost::asio::buffer(bad_request);
+  case reply::unauthorized:
+    return boost::asio::buffer(unauthorized);
+  case reply::forbidden:
+    return boost::asio::buffer(forbidden);
+  case reply::not_found:
+    return boost::asio::buffer(not_found);
+  case reply::internal_server_error:
+    return boost::asio::buffer(internal_server_error);
+  case reply::not_implemented:
+    return boost::asio::buffer(not_implemented);
+  case reply::bad_gateway:
+    return boost::asio::buffer(bad_gateway);
+  case reply::service_unavailable:
+    return boost::asio::buffer(service_unavailable);
+  default:
+    return boost::asio::buffer(internal_server_error);
+  }
+}
+
+} // namespace status_strings
+
+namespace misc_strings {
+
+const char name_value_separator[] = { ':', ' ' };
+const char crlf[] = { '\r', '\n' };
+
+} // namespace misc_strings
+
+std::vector<boost::asio::const_buffer> reply::to_buffers()
+{
+  std::vector<boost::asio::const_buffer> buffers;
+  buffers.push_back(status_strings::to_buffer(status));
+  for (std::size_t i = 0; i < headers.size(); ++i)
+  {
+    header& h = headers[i];
+    buffers.push_back(boost::asio::buffer(h.name));
+    buffers.push_back(boost::asio::buffer(misc_strings::name_value_separator));
+    buffers.push_back(boost::asio::buffer(h.value));
+    buffers.push_back(boost::asio::buffer(misc_strings::crlf));
+  }
+  buffers.push_back(boost::asio::buffer(misc_strings::crlf));
+  buffers.push_back(boost::asio::buffer(content));
+  return buffers;
+}
+
+namespace stock_replies {
+
+const char ok[] = "";
+const char created[] =
+  "<html>"
+  "<head><title>Created</title></head>"
+  "<body><h1>201 Created</h1></body>"
+  "</html>";
+const char accepted[] =
+  "<html>"
+  "<head><title>Accepted</title></head>"
+  "<body><h1>202 Accepted</h1></body>"
+  "</html>";
+const char no_content[] =
+  "<html>"
+  "<head><title>No Content</title></head>"
+  "<body><h1>204 Content</h1></body>"
+  "</html>";
+const char multiple_choices[] =
+  "<html>"
+  "<head><title>Multiple Choices</title></head>"
+  "<body><h1>300 Multiple Choices</h1></body>"
+  "</html>";
+const char moved_permanently[] =
+  "<html>"
+  "<head><title>Moved Permanently</title></head>"
+  "<body><h1>301 Moved Permanently</h1></body>"
+  "</html>";
+const char moved_temporarily[] =
+  "<html>"
+  "<head><title>Moved Temporarily</title></head>"
+  "<body><h1>302 Moved Temporarily</h1></body>"
+  "</html>";
+const char not_modified[] =
+  "<html>"
+  "<head><title>Not Modified</title></head>"
+  "<body><h1>304 Not Modified</h1></body>"
+  "</html>";
+const char bad_request[] =
+  "<html>"
+  "<head><title>Bad Request</title></head>"
+  "<body><h1>400 Bad Request</h1></body>"
+  "</html>";
+const char unauthorized[] =
+  "<html>"
+  "<head><title>Unauthorized</title></head>"
+  "<body><h1>401 Unauthorized</h1></body>"
+  "</html>";
+const char forbidden[] =
+  "<html>"
+  "<head><title>Forbidden</title></head>"
+  "<body><h1>403 Forbidden</h1></body>"
+  "</html>";
+const char not_found[] =
+  "<html>"
+  "<head><title>Not Found</title></head>"
+  "<body><h1>404 Not Found</h1></body>"
+  "</html>";
+const char internal_server_error[] =
+  "<html>"
+  "<head><title>Internal Server Error</title></head>"
+  "<body><h1>500 Internal Server Error</h1></body>"
+  "</html>";
+const char not_implemented[] =
+  "<html>"
+  "<head><title>Not Implemented</title></head>"
+  "<body><h1>501 Not Implemented</h1></body>"
+  "</html>";
+const char bad_gateway[] =
+  "<html>"
+  "<head><title>Bad Gateway</title></head>"
+  "<body><h1>502 Bad Gateway</h1></body>"
+  "</html>";
+const char service_unavailable[] =
+  "<html>"
+  "<head><title>Service Unavailable</title></head>"
+  "<body><h1>503 Service Unavailable</h1></body>"
+  "</html>";
+
+std::string to_string(reply::status_type status)
+{
+  switch (status)
+  {
+  case reply::ok:
+    return ok;
+  case reply::created:
+    return created;
+  case reply::accepted:
+    return accepted;
+  case reply::no_content:
+    return no_content;
+  case reply::multiple_choices:
+    return multiple_choices;
+  case reply::moved_permanently:
+    return moved_permanently;
+  case reply::moved_temporarily:
+    return moved_temporarily;
+  case reply::not_modified:
+    return not_modified;
+  case reply::bad_request:
+    return bad_request;
+  case reply::unauthorized:
+    return unauthorized;
+  case reply::forbidden:
+    return forbidden;
+  case reply::not_found:
+    return not_found;
+  case reply::internal_server_error:
+    return internal_server_error;
+  case reply::not_implemented:
+    return not_implemented;
+  case reply::bad_gateway:
+    return bad_gateway;
+  case reply::service_unavailable:
+    return service_unavailable;
+  default:
+    return internal_server_error;
+  }
+}
+
+} // namespace stock_replies
+
+reply reply::stock_reply(reply::status_type status)
+{
+  reply rep;
+  rep.status = status;
+  rep.content = stock_replies::to_string(status);
+  rep.headers.resize(2);
+  rep.headers[0].name = "Content-Length";
+  rep.headers[0].value = boost::lexical_cast<std::string>(rep.content.size());
+  rep.headers[1].name = "Content-Type";
+  rep.headers[1].value = "text/html";
+  return rep;
+}
+
+} // namespace server
+} // namespace http

doc/html/boost_asio/example/cpp03/http/server/reply.hpp

@@ -0,0 +1,64 @@
+//
+// reply.hpp
+// ~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef HTTP_REPLY_HPP
+#define HTTP_REPLY_HPP
+
+#include <string>
+#include <vector>
+#include <boost/asio.hpp>
+#include "header.hpp"
+
+namespace http {
+namespace server {
+
+/// A reply to be sent to a client.
+struct reply
+{
+  /// The status of the reply.
+  enum status_type
+  {
+    ok = 200,
+    created = 201,
+    accepted = 202,
+    no_content = 204,
+    multiple_choices = 300,
+    moved_permanently = 301,
+    moved_temporarily = 302,
+    not_modified = 304,
+    bad_request = 400,
+    unauthorized = 401,
+    forbidden = 403,
+    not_found = 404,
+    internal_server_error = 500,
+    not_implemented = 501,
+    bad_gateway = 502,
+    service_unavailable = 503
+  } status;
+
+  /// The headers to be included in the reply.
+  std::vector<header> headers;
+
+  /// The content to be sent in the reply.
+  std::string content;
+
+  /// Convert the reply into a vector of buffers. The buffers do not own the
+  /// underlying memory blocks, therefore the reply object must remain valid and
+  /// not be changed until the write operation has completed.
+  std::vector<boost::asio::const_buffer> to_buffers();
+
+  /// Get a stock reply.
+  static reply stock_reply(status_type status);
+};
+
+} // namespace server
+} // namespace http
+
+#endif // HTTP_REPLY_HPP

doc/html/boost_asio/example/cpp03/http/server/request.hpp

@@ -0,0 +1,34 @@
+//
+// request.hpp
+// ~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef HTTP_REQUEST_HPP
+#define HTTP_REQUEST_HPP
+
+#include <string>
+#include <vector>
+#include "header.hpp"
+
+namespace http {
+namespace server {
+
+/// A request received from a client.
+struct request
+{
+  std::string method;
+  std::string uri;
+  int http_version_major;
+  int http_version_minor;
+  std::vector<header> headers;
+};
+
+} // namespace server
+} // namespace http
+
+#endif // HTTP_REQUEST_HPP

doc/html/boost_asio/example/cpp03/http/server/request_handler.cpp

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+//
+// request_handler.cpp
+// ~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include "request_handler.hpp"
+#include <fstream>
+#include <sstream>
+#include <string>
+#include <boost/lexical_cast.hpp>
+#include "mime_types.hpp"
+#include "reply.hpp"
+#include "request.hpp"
+
+namespace http {
+namespace server {
+
+request_handler::request_handler(const std::string& doc_root)
+  : doc_root_(doc_root)
+{
+}
+
+void request_handler::handle_request(const request& req, reply& rep)
+{
+  // Decode url to path.
+  std::string request_path;
+  if (!url_decode(req.uri, request_path))
+  {
+    rep = reply::stock_reply(reply::bad_request);
+    return;
+  }
+
+  // Request path must be absolute and not contain "..".
+  if (request_path.empty() || request_path[0] != '/'
+      || request_path.find("..") != std::string::npos)
+  {
+    rep = reply::stock_reply(reply::bad_request);
+    return;
+  }
+
+  // If path ends in slash (i.e. is a directory) then add "index.html".
+  if (request_path[request_path.size() - 1] == '/')
+  {
+    request_path += "index.html";
+  }
+
+  // Determine the file extension.
+  std::size_t last_slash_pos = request_path.find_last_of("/");
+  std::size_t last_dot_pos = request_path.find_last_of(".");
+  std::string extension;
+  if (last_dot_pos != std::string::npos && last_dot_pos > last_slash_pos)
+  {
+    extension = request_path.substr(last_dot_pos + 1);
+  }
+
+  // Open the file to send back.
+  std::string full_path = doc_root_ + request_path;
+  std::ifstream is(full_path.c_str(), std::ios::in | std::ios::binary);
+  if (!is)
+  {
+    rep = reply::stock_reply(reply::not_found);
+    return;
+  }
+
+  // Fill out the reply to be sent to the client.
+  rep.status = reply::ok;
+  char buf[512];
+  while (is.read(buf, sizeof(buf)).gcount() > 0)
+    rep.content.append(buf, is.gcount());
+  rep.headers.resize(2);
+  rep.headers[0].name = "Content-Length";
+  rep.headers[0].value = boost::lexical_cast<std::string>(rep.content.size());
+  rep.headers[1].name = "Content-Type";
+  rep.headers[1].value = mime_types::extension_to_type(extension);
+}
+
+bool request_handler::url_decode(const std::string& in, std::string& out)
+{
+  out.clear();
+  out.reserve(in.size());
+  for (std::size_t i = 0; i < in.size(); ++i)
+  {
+    if (in[i] == '%')
+    {
+      if (i + 3 <= in.size())
+      {
+        int value = 0;
+        std::istringstream is(in.substr(i + 1, 2));
+        if (is >> std::hex >> value)
+        {
+          out += static_cast<char>(value);
+          i += 2;
+        }
+        else
+        {
+          return false;
+        }
+      }
+      else
+      {
+        return false;
+      }
+    }
+    else if (in[i] == '+')
+    {
+      out += ' ';
+    }
+    else
+    {
+      out += in[i];
+    }
+  }
+  return true;
+}
+
+} // namespace server
+} // namespace http

doc/html/boost_asio/example/cpp03/http/server/request_handler.hpp

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+//
+// request_handler.hpp
+// ~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef HTTP_REQUEST_HANDLER_HPP
+#define HTTP_REQUEST_HANDLER_HPP
+
+#include <string>
+#include <boost/noncopyable.hpp>
+
+namespace http {
+namespace server {
+
+struct reply;
+struct request;
+
+/// The common handler for all incoming requests.
+class request_handler
+  : private boost::noncopyable
+{
+public:
+  /// Construct with a directory containing files to be served.
+  explicit request_handler(const std::string& doc_root);
+
+  /// Handle a request and produce a reply.
+  void handle_request(const request& req, reply& rep);
+
+private:
+  /// The directory containing the files to be served.
+  std::string doc_root_;
+
+  /// Perform URL-decoding on a string. Returns false if the encoding was
+  /// invalid.
+  static bool url_decode(const std::string& in, std::string& out);
+};
+
+} // namespace server
+} // namespace http
+
+#endif // HTTP_REQUEST_HANDLER_HPP

doc/html/boost_asio/example/cpp03/http/server/request_parser.cpp

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+//
+// request_parser.cpp
+// ~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include "request_parser.hpp"
+#include "request.hpp"
+
+namespace http {
+namespace server {
+
+request_parser::request_parser()
+  : state_(method_start)
+{
+}
+
+void request_parser::reset()
+{
+  state_ = method_start;
+}
+
+boost::tribool request_parser::consume(request& req, char input)
+{
+  switch (state_)
+  {
+  case method_start:
+    if (!is_char(input) || is_ctl(input) || is_tspecial(input))
+    {
+      return false;
+    }
+    else
+    {
+      state_ = method;
+      req.method.push_back(input);
+      return boost::indeterminate;
+    }
+  case method:
+    if (input == ' ')
+    {
+      state_ = uri;
+      return boost::indeterminate;
+    }
+    else if (!is_char(input) || is_ctl(input) || is_tspecial(input))
+    {
+      return false;
+    }
+    else
+    {
+      req.method.push_back(input);
+      return boost::indeterminate;
+    }
+  case uri:
+    if (input == ' ')
+    {
+      state_ = http_version_h;
+      return boost::indeterminate;
+    }
+    else if (is_ctl(input))
+    {
+      return false;
+    }
+    else
+    {
+      req.uri.push_back(input);
+      return boost::indeterminate;
+    }
+  case http_version_h:
+    if (input == 'H')
+    {
+      state_ = http_version_t_1;
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case http_version_t_1:
+    if (input == 'T')
+    {
+      state_ = http_version_t_2;
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case http_version_t_2:
+    if (input == 'T')
+    {
+      state_ = http_version_p;
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case http_version_p:
+    if (input == 'P')
+    {
+      state_ = http_version_slash;
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case http_version_slash:
+    if (input == '/')
+    {
+      req.http_version_major = 0;
+      req.http_version_minor = 0;
+      state_ = http_version_major_start;
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case http_version_major_start:
+    if (is_digit(input))
+    {
+      req.http_version_major = req.http_version_major * 10 + input - '0';
+      state_ = http_version_major;
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case http_version_major:
+    if (input == '.')
+    {
+      state_ = http_version_minor_start;
+      return boost::indeterminate;
+    }
+    else if (is_digit(input))
+    {
+      req.http_version_major = req.http_version_major * 10 + input - '0';
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case http_version_minor_start:
+    if (is_digit(input))
+    {
+      req.http_version_minor = req.http_version_minor * 10 + input - '0';
+      state_ = http_version_minor;
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case http_version_minor:
+    if (input == '\r')
+    {
+      state_ = expecting_newline_1;
+      return boost::indeterminate;
+    }
+    else if (is_digit(input))
+    {
+      req.http_version_minor = req.http_version_minor * 10 + input - '0';
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case expecting_newline_1:
+    if (input == '\n')
+    {
+      state_ = header_line_start;
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case header_line_start:
+    if (input == '\r')
+    {
+      state_ = expecting_newline_3;
+      return boost::indeterminate;
+    }
+    else if (!req.headers.empty() && (input == ' ' || input == '\t'))
+    {
+      state_ = header_lws;
+      return boost::indeterminate;
+    }
+    else if (!is_char(input) || is_ctl(input) || is_tspecial(input))
+    {
+      return false;
+    }
+    else
+    {
+      req.headers.push_back(header());
+      req.headers.back().name.push_back(input);
+      state_ = header_name;
+      return boost::indeterminate;
+    }
+  case header_lws:
+    if (input == '\r')
+    {
+      state_ = expecting_newline_2;
+      return boost::indeterminate;
+    }
+    else if (input == ' ' || input == '\t')
+    {
+      return boost::indeterminate;
+    }
+    else if (is_ctl(input))
+    {
+      return false;
+    }
+    else
+    {
+      state_ = header_value;
+      req.headers.back().value.push_back(input);
+      return boost::indeterminate;
+    }
+  case header_name:
+    if (input == ':')
+    {
+      state_ = space_before_header_value;
+      return boost::indeterminate;
+    }
+    else if (!is_char(input) || is_ctl(input) || is_tspecial(input))
+    {
+      return false;
+    }
+    else
+    {
+      req.headers.back().name.push_back(input);
+      return boost::indeterminate;
+    }
+  case space_before_header_value:
+    if (input == ' ')
+    {
+      state_ = header_value;
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case header_value:
+    if (input == '\r')
+    {
+      state_ = expecting_newline_2;
+      return boost::indeterminate;
+    }
+    else if (is_ctl(input))
+    {
+      return false;
+    }
+    else
+    {
+      req.headers.back().value.push_back(input);
+      return boost::indeterminate;
+    }
+  case expecting_newline_2:
+    if (input == '\n')
+    {
+      state_ = header_line_start;
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case expecting_newline_3:
+    return (input == '\n');
+  default:
+    return false;
+  }
+}
+
+bool request_parser::is_char(int c)
+{
+  return c >= 0 && c <= 127;
+}
+
+bool request_parser::is_ctl(int c)
+{
+  return (c >= 0 && c <= 31) || (c == 127);
+}
+
+bool request_parser::is_tspecial(int c)
+{
+  switch (c)
+  {
+  case '(': case ')': case '<': case '>': case '@':
+  case ',': case ';': case ':': case '\\': case '"':
+  case '/': case '[': case ']': case '?': case '=':
+  case '{': case '}': case ' ': case '\t':
+    return true;
+  default:
+    return false;
+  }
+}
+
+bool request_parser::is_digit(int c)
+{
+  return c >= '0' && c <= '9';
+}
+
+} // namespace server
+} // namespace http

doc/html/boost_asio/example/cpp03/http/server/request_parser.hpp

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+//
+// request_parser.hpp
+// ~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef HTTP_REQUEST_PARSER_HPP
+#define HTTP_REQUEST_PARSER_HPP
+
+#include <boost/logic/tribool.hpp>
+#include <boost/tuple/tuple.hpp>
+
+namespace http {
+namespace server {
+
+struct request;
+
+/// Parser for incoming requests.
+class request_parser
+{
+public:
+  /// Construct ready to parse the request method.
+  request_parser();
+
+  /// Reset to initial parser state.
+  void reset();
+
+  /// Parse some data. The tribool return value is true when a complete request
+  /// has been parsed, false if the data is invalid, indeterminate when more
+  /// data is required. The InputIterator return value indicates how much of the
+  /// input has been consumed.
+  template <typename InputIterator>
+  boost::tuple<boost::tribool, InputIterator> parse(request& req,
+      InputIterator begin, InputIterator end)
+  {
+    while (begin != end)
+    {
+      boost::tribool result = consume(req, *begin++);
+      if (result || !result)
+        return boost::make_tuple(result, begin);
+    }
+    boost::tribool result = boost::indeterminate;
+    return boost::make_tuple(result, begin);
+  }
+
+private:
+  /// Handle the next character of input.
+  boost::tribool consume(request& req, char input);
+
+  /// Check if a byte is an HTTP character.
+  static bool is_char(int c);
+
+  /// Check if a byte is an HTTP control character.
+  static bool is_ctl(int c);
+
+  /// Check if a byte is defined as an HTTP tspecial character.
+  static bool is_tspecial(int c);
+
+  /// Check if a byte is a digit.
+  static bool is_digit(int c);
+
+  /// The current state of the parser.
+  enum state
+  {
+    method_start,
+    method,
+    uri,
+    http_version_h,
+    http_version_t_1,
+    http_version_t_2,
+    http_version_p,
+    http_version_slash,
+    http_version_major_start,
+    http_version_major,
+    http_version_minor_start,
+    http_version_minor,
+    expecting_newline_1,
+    header_line_start,
+    header_lws,
+    header_name,
+    space_before_header_value,
+    header_value,
+    expecting_newline_2,
+    expecting_newline_3
+  } state_;
+};
+
+} // namespace server
+} // namespace http
+
+#endif // HTTP_REQUEST_PARSER_HPP

doc/html/boost_asio/example/cpp03/http/server/server.cpp

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+//
+// server.cpp
+// ~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include "server.hpp"
+#include <boost/bind/bind.hpp>
+#include <signal.h>
+
+namespace http {
+namespace server {
+
+server::server(const std::string& address, const std::string& port,
+    const std::string& doc_root)
+  : io_context_(),
+    signals_(io_context_),
+    acceptor_(io_context_),
+    connection_manager_(),
+    new_connection_(),
+    request_handler_(doc_root)
+{
+  // Register to handle the signals that indicate when the server should exit.
+  // It is safe to register for the same signal multiple times in a program,
+  // provided all registration for the specified signal is made through Asio.
+  signals_.add(SIGINT);
+  signals_.add(SIGTERM);
+#if defined(SIGQUIT)
+  signals_.add(SIGQUIT);
+#endif // defined(SIGQUIT)
+  signals_.async_wait(boost::bind(&server::handle_stop, this));
+
+  // Open the acceptor with the option to reuse the address (i.e. SO_REUSEADDR).
+  boost::asio::ip::tcp::resolver resolver(io_context_);
+  boost::asio::ip::tcp::endpoint endpoint =
+    *resolver.resolve(address, port).begin();
+  acceptor_.open(endpoint.protocol());
+  acceptor_.set_option(boost::asio::ip::tcp::acceptor::reuse_address(true));
+  acceptor_.bind(endpoint);
+  acceptor_.listen();
+
+  start_accept();
+}
+
+void server::run()
+{
+  // The io_context::run() call will block until all asynchronous operations
+  // have finished. While the server is running, there is always at least one
+  // asynchronous operation outstanding: the asynchronous accept call waiting
+  // for new incoming connections.
+  io_context_.run();
+}
+
+void server::start_accept()
+{
+  new_connection_.reset(new connection(io_context_,
+        connection_manager_, request_handler_));
+  acceptor_.async_accept(new_connection_->socket(),
+      boost::bind(&server::handle_accept, this,
+        boost::asio::placeholders::error));
+}
+
+void server::handle_accept(const boost::system::error_code& e)
+{
+  // Check whether the server was stopped by a signal before this completion
+  // handler had a chance to run.
+  if (!acceptor_.is_open())
+  {
+    return;
+  }
+
+  if (!e)
+  {
+    connection_manager_.start(new_connection_);
+  }
+
+  start_accept();
+}
+
+void server::handle_stop()
+{
+  // The server is stopped by cancelling all outstanding asynchronous
+  // operations. Once all operations have finished the io_context::run() call
+  // will exit.
+  acceptor_.close();
+  connection_manager_.stop_all();
+}
+
+} // namespace server
+} // namespace http

doc/html/boost_asio/example/cpp03/http/server/server.hpp

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+//
+// server.hpp
+// ~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef HTTP_SERVER_HPP
+#define HTTP_SERVER_HPP
+
+#include <boost/asio.hpp>
+#include <string>
+#include <boost/noncopyable.hpp>
+#include "connection.hpp"
+#include "connection_manager.hpp"
+#include "request_handler.hpp"
+
+namespace http {
+namespace server {
+
+/// The top-level class of the HTTP server.
+class server
+  : private boost::noncopyable
+{
+public:
+  /// Construct the server to listen on the specified TCP address and port, and
+  /// serve up files from the given directory.
+  explicit server(const std::string& address, const std::string& port,
+      const std::string& doc_root);
+
+  /// Run the server's io_context loop.
+  void run();
+
+private:
+  /// Initiate an asynchronous accept operation.
+  void start_accept();
+
+  /// Handle completion of an asynchronous accept operation.
+  void handle_accept(const boost::system::error_code& e);
+
+  /// Handle a request to stop the server.
+  void handle_stop();
+
+  /// The io_context used to perform asynchronous operations.
+  boost::asio::io_context io_context_;
+
+  /// The signal_set is used to register for process termination notifications.
+  boost::asio::signal_set signals_;
+
+  /// Acceptor used to listen for incoming connections.
+  boost::asio::ip::tcp::acceptor acceptor_;
+
+  /// The connection manager which owns all live connections.
+  connection_manager connection_manager_;
+
+  /// The next connection to be accepted.
+  connection_ptr new_connection_;
+
+  /// The handler for all incoming requests.
+  request_handler request_handler_;
+};
+
+} // namespace server
+} // namespace http
+
+#endif // HTTP_SERVER_HPP

doc/html/boost_asio/example/cpp03/http/server2/connection.cpp

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+//
+// connection.cpp
+// ~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include "connection.hpp"
+#include <vector>
+#include <boost/bind/bind.hpp>
+#include "request_handler.hpp"
+
+namespace http {
+namespace server2 {
+
+connection::connection(boost::asio::io_context& io_context,
+    request_handler& handler)
+  : socket_(io_context),
+    request_handler_(handler)
+{
+}
+
+boost::asio::ip::tcp::socket& connection::socket()
+{
+  return socket_;
+}
+
+void connection::start()
+{
+  socket_.async_read_some(boost::asio::buffer(buffer_),
+      boost::bind(&connection::handle_read, shared_from_this(),
+        boost::asio::placeholders::error,
+        boost::asio::placeholders::bytes_transferred));
+}
+
+void connection::handle_read(const boost::system::error_code& e,
+    std::size_t bytes_transferred)
+{
+  if (!e)
+  {
+    boost::tribool result;
+    boost::tie(result, boost::tuples::ignore) = request_parser_.parse(
+        request_, buffer_.data(), buffer_.data() + bytes_transferred);
+
+    if (result)
+    {
+      request_handler_.handle_request(request_, reply_);
+      boost::asio::async_write(socket_, reply_.to_buffers(),
+          boost::bind(&connection::handle_write, shared_from_this(),
+            boost::asio::placeholders::error));
+    }
+    else if (!result)
+    {
+      reply_ = reply::stock_reply(reply::bad_request);
+      boost::asio::async_write(socket_, reply_.to_buffers(),
+          boost::bind(&connection::handle_write, shared_from_this(),
+            boost::asio::placeholders::error));
+    }
+    else
+    {
+      socket_.async_read_some(boost::asio::buffer(buffer_),
+          boost::bind(&connection::handle_read, shared_from_this(),
+            boost::asio::placeholders::error,
+            boost::asio::placeholders::bytes_transferred));
+    }
+  }
+
+  // If an error occurs then no new asynchronous operations are started. This
+  // means that all shared_ptr references to the connection object will
+  // disappear and the object will be destroyed automatically after this
+  // handler returns. The connection class's destructor closes the socket.
+}
+
+void connection::handle_write(const boost::system::error_code& e)
+{
+  if (!e)
+  {
+    // Initiate graceful connection closure.
+    boost::system::error_code ignored_ec;
+    socket_.shutdown(boost::asio::ip::tcp::socket::shutdown_both, ignored_ec);
+  }
+
+  // No new asynchronous operations are started. This means that all shared_ptr
+  // references to the connection object will disappear and the object will be
+  // destroyed automatically after this handler returns. The connection class's
+  // destructor closes the socket.
+}
+
+} // namespace server2
+} // namespace http

doc/html/boost_asio/example/cpp03/http/server2/connection.hpp

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+//
+// connection.hpp
+// ~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef HTTP_SERVER2_CONNECTION_HPP
+#define HTTP_SERVER2_CONNECTION_HPP
+
+#include <boost/asio.hpp>
+#include <boost/array.hpp>
+#include <boost/noncopyable.hpp>
+#include <boost/shared_ptr.hpp>
+#include <boost/enable_shared_from_this.hpp>
+#include "reply.hpp"
+#include "request.hpp"
+#include "request_handler.hpp"
+#include "request_parser.hpp"
+
+namespace http {
+namespace server2 {
+
+/// Represents a single connection from a client.
+class connection
+  : public boost::enable_shared_from_this<connection>,
+    private boost::noncopyable
+{
+public:
+  /// Construct a connection with the given io_context.
+  explicit connection(boost::asio::io_context& io_context,
+      request_handler& handler);
+
+  /// Get the socket associated with the connection.
+  boost::asio::ip::tcp::socket& socket();
+
+  /// Start the first asynchronous operation for the connection.
+  void start();
+
+private:
+  /// Handle completion of a read operation.
+  void handle_read(const boost::system::error_code& e,
+      std::size_t bytes_transferred);
+
+  /// Handle completion of a write operation.
+  void handle_write(const boost::system::error_code& e);
+
+  /// Socket for the connection.
+  boost::asio::ip::tcp::socket socket_;
+
+  /// The handler used to process the incoming request.
+  request_handler& request_handler_;
+
+  /// Buffer for incoming data.
+  boost::array<char, 8192> buffer_;
+
+  /// The incoming request.
+  request request_;
+
+  /// The parser for the incoming request.
+  request_parser request_parser_;
+
+  /// The reply to be sent back to the client.
+  reply reply_;
+};
+
+typedef boost::shared_ptr<connection> connection_ptr;
+
+} // namespace server2
+} // namespace http
+
+#endif // HTTP_SERVER2_CONNECTION_HPP

doc/html/boost_asio/example/cpp03/http/server2/header.hpp

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+//
+// header.hpp
+// ~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef HTTP_SERVER2_HEADER_HPP
+#define HTTP_SERVER2_HEADER_HPP
+
+#include <string>
+
+namespace http {
+namespace server2 {
+
+struct header
+{
+  std::string name;
+  std::string value;
+};
+
+} // namespace server2
+} // namespace http
+
+#endif // HTTP_SERVER2_HEADER_HPP

doc/html/boost_asio/example/cpp03/http/server2/io_context_pool.cpp

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+//
+// io_context_pool.cpp
+// ~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include "server.hpp"
+#include <stdexcept>
+#include <boost/thread/thread.hpp>
+#include <boost/bind/bind.hpp>
+#include <boost/shared_ptr.hpp>
+
+namespace http {
+namespace server2 {
+
+io_context_pool::io_context_pool(std::size_t pool_size)
+  : next_io_context_(0)
+{
+  if (pool_size == 0)
+    throw std::runtime_error("io_context_pool size is 0");
+
+  // Give all the io_contexts work to do so that their run() functions will not
+  // exit until they are explicitly stopped.
+  for (std::size_t i = 0; i < pool_size; ++i)
+  {
+    io_context_ptr io_context(new boost::asio::io_context);
+    io_contexts_.push_back(io_context);
+    work_.push_back(boost::asio::require(io_context->get_executor(),
+          boost::asio::execution::outstanding_work.tracked));
+  }
+}
+
+void io_context_pool::run()
+{
+  // Create a pool of threads to run all of the io_contexts.
+  std::vector<boost::shared_ptr<boost::thread> > threads;
+  for (std::size_t i = 0; i < io_contexts_.size(); ++i)
+  {
+    boost::shared_ptr<boost::thread> thread(new boost::thread(
+          boost::bind(&boost::asio::io_context::run, io_contexts_[i])));
+    threads.push_back(thread);
+  }
+
+  // Wait for all threads in the pool to exit.
+  for (std::size_t i = 0; i < threads.size(); ++i)
+    threads[i]->join();
+}
+
+void io_context_pool::stop()
+{
+  // Explicitly stop all io_contexts.
+  for (std::size_t i = 0; i < io_contexts_.size(); ++i)
+    io_contexts_[i]->stop();
+}
+
+boost::asio::io_context& io_context_pool::get_io_context()
+{
+  // Use a round-robin scheme to choose the next io_context to use.
+  boost::asio::io_context& io_context = *io_contexts_[next_io_context_];
+  ++next_io_context_;
+  if (next_io_context_ == io_contexts_.size())
+    next_io_context_ = 0;
+  return io_context;
+}
+
+} // namespace server2
+} // namespace http

doc/html/boost_asio/example/cpp03/http/server2/io_context_pool.hpp

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+//
+// io_context_pool.hpp
+// ~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef HTTP_SERVER2_IO_SERVICE_POOL_HPP
+#define HTTP_SERVER2_IO_SERVICE_POOL_HPP
+
+#include <boost/asio.hpp>
+#include <list>
+#include <vector>
+#include <boost/noncopyable.hpp>
+#include <boost/shared_ptr.hpp>
+
+namespace http {
+namespace server2 {
+
+/// A pool of io_context objects.
+class io_context_pool
+  : private boost::noncopyable
+{
+public:
+  /// Construct the io_context pool.
+  explicit io_context_pool(std::size_t pool_size);
+
+  /// Run all io_context objects in the pool.
+  void run();
+
+  /// Stop all io_context objects in the pool.
+  void stop();
+
+  /// Get an io_context to use.
+  boost::asio::io_context& get_io_context();
+
+private:
+  typedef boost::shared_ptr<boost::asio::io_context> io_context_ptr;
+
+  /// The pool of io_contexts.
+  std::vector<io_context_ptr> io_contexts_;
+
+  /// The work-tracking executors that keep the io_contexts running.
+  std::list<boost::asio::any_io_executor> work_;
+
+  /// The next io_context to use for a connection.
+  std::size_t next_io_context_;
+};
+
+} // namespace server2
+} // namespace http
+
+#endif // HTTP_SERVER2_IO_SERVICE_POOL_HPP

doc/html/boost_asio/example/cpp03/http/server2/main.cpp

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+//
+// main.cpp
+// ~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <iostream>
+#include <string>
+#include <boost/asio.hpp>
+#include <boost/bind/bind.hpp>
+#include <boost/lexical_cast.hpp>
+#include "server.hpp"
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    // Check command line arguments.
+    if (argc != 5)
+    {
+      std::cerr << "Usage: http_server <address> <port> <threads> <doc_root>\n";
+      std::cerr << "  For IPv4, try:\n";
+      std::cerr << "    receiver 0.0.0.0 80 1 .\n";
+      std::cerr << "  For IPv6, try:\n";
+      std::cerr << "    receiver 0::0 80 1 .\n";
+      return 1;
+    }
+
+    // Initialise the server.
+    std::size_t num_threads = boost::lexical_cast<std::size_t>(argv[3]);
+    http::server2::server s(argv[1], argv[2], argv[4], num_threads);
+
+    // Run the server until stopped.
+    s.run();
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << "exception: " << e.what() << "\n";
+  }
+
+  return 0;
+}

doc/html/boost_asio/example/cpp03/http/server2/mime_types.cpp

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+//
+// mime_types.cpp
+// ~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include "mime_types.hpp"
+
+namespace http {
+namespace server2 {
+namespace mime_types {
+
+struct mapping
+{
+  const char* extension;
+  const char* mime_type;
+} mappings[] =
+{
+  { "gif", "image/gif" },
+  { "htm", "text/html" },
+  { "html", "text/html" },
+  { "jpg", "image/jpeg" },
+  { "png", "image/png" },
+  { 0, 0 } // Marks end of list.
+};
+
+std::string extension_to_type(const std::string& extension)
+{
+  for (mapping* m = mappings; m->extension; ++m)
+  {
+    if (m->extension == extension)
+    {
+      return m->mime_type;
+    }
+  }
+
+  return "text/plain";
+}
+
+} // namespace mime_types
+} // namespace server2
+} // namespace http

doc/html/boost_asio/example/cpp03/http/server2/mime_types.hpp

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+//
+// mime_types.hpp
+// ~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef HTTP_SERVER2_MIME_TYPES_HPP
+#define HTTP_SERVER2_MIME_TYPES_HPP
+
+#include <string>
+
+namespace http {
+namespace server2 {
+namespace mime_types {
+
+/// Convert a file extension into a MIME type.
+std::string extension_to_type(const std::string& extension);
+
+} // namespace mime_types
+} // namespace server2
+} // namespace http
+
+#endif // HTTP_SERVER2_MIME_TYPES_HPP

doc/html/boost_asio/example/cpp03/http/server2/reply.cpp

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+//
+// reply.cpp
+// ~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include "reply.hpp"
+#include <string>
+#include <boost/lexical_cast.hpp>
+
+namespace http {
+namespace server2 {
+
+namespace status_strings {
+
+const std::string ok =
+  "HTTP/1.0 200 OK\r\n";
+const std::string created =
+  "HTTP/1.0 201 Created\r\n";
+const std::string accepted =
+  "HTTP/1.0 202 Accepted\r\n";
+const std::string no_content =
+  "HTTP/1.0 204 No Content\r\n";
+const std::string multiple_choices =
+  "HTTP/1.0 300 Multiple Choices\r\n";
+const std::string moved_permanently =
+  "HTTP/1.0 301 Moved Permanently\r\n";
+const std::string moved_temporarily =
+  "HTTP/1.0 302 Moved Temporarily\r\n";
+const std::string not_modified =
+  "HTTP/1.0 304 Not Modified\r\n";
+const std::string bad_request =
+  "HTTP/1.0 400 Bad Request\r\n";
+const std::string unauthorized =
+  "HTTP/1.0 401 Unauthorized\r\n";
+const std::string forbidden =
+  "HTTP/1.0 403 Forbidden\r\n";
+const std::string not_found =
+  "HTTP/1.0 404 Not Found\r\n";
+const std::string internal_server_error =
+  "HTTP/1.0 500 Internal Server Error\r\n";
+const std::string not_implemented =
+  "HTTP/1.0 501 Not Implemented\r\n";
+const std::string bad_gateway =
+  "HTTP/1.0 502 Bad Gateway\r\n";
+const std::string service_unavailable =
+  "HTTP/1.0 503 Service Unavailable\r\n";
+
+boost::asio::const_buffer to_buffer(reply::status_type status)
+{
+  switch (status)
+  {
+  case reply::ok:
+    return boost::asio::buffer(ok);
+  case reply::created:
+    return boost::asio::buffer(created);
+  case reply::accepted:
+    return boost::asio::buffer(accepted);
+  case reply::no_content:
+    return boost::asio::buffer(no_content);
+  case reply::multiple_choices:
+    return boost::asio::buffer(multiple_choices);
+  case reply::moved_permanently:
+    return boost::asio::buffer(moved_permanently);
+  case reply::moved_temporarily:
+    return boost::asio::buffer(moved_temporarily);
+  case reply::not_modified:
+    return boost::asio::buffer(not_modified);
+  case reply::bad_request:
+    return boost::asio::buffer(bad_request);
+  case reply::unauthorized:
+    return boost::asio::buffer(unauthorized);
+  case reply::forbidden:
+    return boost::asio::buffer(forbidden);
+  case reply::not_found:
+    return boost::asio::buffer(not_found);
+  case reply::internal_server_error:
+    return boost::asio::buffer(internal_server_error);
+  case reply::not_implemented:
+    return boost::asio::buffer(not_implemented);
+  case reply::bad_gateway:
+    return boost::asio::buffer(bad_gateway);
+  case reply::service_unavailable:
+    return boost::asio::buffer(service_unavailable);
+  default:
+    return boost::asio::buffer(internal_server_error);
+  }
+}
+
+} // namespace status_strings
+
+namespace misc_strings {
+
+const char name_value_separator[] = { ':', ' ' };
+const char crlf[] = { '\r', '\n' };
+
+} // namespace misc_strings
+
+std::vector<boost::asio::const_buffer> reply::to_buffers()
+{
+  std::vector<boost::asio::const_buffer> buffers;
+  buffers.push_back(status_strings::to_buffer(status));
+  for (std::size_t i = 0; i < headers.size(); ++i)
+  {
+    header& h = headers[i];
+    buffers.push_back(boost::asio::buffer(h.name));
+    buffers.push_back(boost::asio::buffer(misc_strings::name_value_separator));
+    buffers.push_back(boost::asio::buffer(h.value));
+    buffers.push_back(boost::asio::buffer(misc_strings::crlf));
+  }
+  buffers.push_back(boost::asio::buffer(misc_strings::crlf));
+  buffers.push_back(boost::asio::buffer(content));
+  return buffers;
+}
+
+namespace stock_replies {
+
+const char ok[] = "";
+const char created[] =
+  "<html>"
+  "<head><title>Created</title></head>"
+  "<body><h1>201 Created</h1></body>"
+  "</html>";
+const char accepted[] =
+  "<html>"
+  "<head><title>Accepted</title></head>"
+  "<body><h1>202 Accepted</h1></body>"
+  "</html>";
+const char no_content[] =
+  "<html>"
+  "<head><title>No Content</title></head>"
+  "<body><h1>204 Content</h1></body>"
+  "</html>";
+const char multiple_choices[] =
+  "<html>"
+  "<head><title>Multiple Choices</title></head>"
+  "<body><h1>300 Multiple Choices</h1></body>"
+  "</html>";
+const char moved_permanently[] =
+  "<html>"
+  "<head><title>Moved Permanently</title></head>"
+  "<body><h1>301 Moved Permanently</h1></body>"
+  "</html>";
+const char moved_temporarily[] =
+  "<html>"
+  "<head><title>Moved Temporarily</title></head>"
+  "<body><h1>302 Moved Temporarily</h1></body>"
+  "</html>";
+const char not_modified[] =
+  "<html>"
+  "<head><title>Not Modified</title></head>"
+  "<body><h1>304 Not Modified</h1></body>"
+  "</html>";
+const char bad_request[] =
+  "<html>"
+  "<head><title>Bad Request</title></head>"
+  "<body><h1>400 Bad Request</h1></body>"
+  "</html>";
+const char unauthorized[] =
+  "<html>"
+  "<head><title>Unauthorized</title></head>"
+  "<body><h1>401 Unauthorized</h1></body>"
+  "</html>";
+const char forbidden[] =
+  "<html>"
+  "<head><title>Forbidden</title></head>"
+  "<body><h1>403 Forbidden</h1></body>"
+  "</html>";
+const char not_found[] =
+  "<html>"
+  "<head><title>Not Found</title></head>"
+  "<body><h1>404 Not Found</h1></body>"
+  "</html>";
+const char internal_server_error[] =
+  "<html>"
+  "<head><title>Internal Server Error</title></head>"
+  "<body><h1>500 Internal Server Error</h1></body>"
+  "</html>";
+const char not_implemented[] =
+  "<html>"
+  "<head><title>Not Implemented</title></head>"
+  "<body><h1>501 Not Implemented</h1></body>"
+  "</html>";
+const char bad_gateway[] =
+  "<html>"
+  "<head><title>Bad Gateway</title></head>"
+  "<body><h1>502 Bad Gateway</h1></body>"
+  "</html>";
+const char service_unavailable[] =
+  "<html>"
+  "<head><title>Service Unavailable</title></head>"
+  "<body><h1>503 Service Unavailable</h1></body>"
+  "</html>";
+
+std::string to_string(reply::status_type status)
+{
+  switch (status)
+  {
+  case reply::ok:
+    return ok;
+  case reply::created:
+    return created;
+  case reply::accepted:
+    return accepted;
+  case reply::no_content:
+    return no_content;
+  case reply::multiple_choices:
+    return multiple_choices;
+  case reply::moved_permanently:
+    return moved_permanently;
+  case reply::moved_temporarily:
+    return moved_temporarily;
+  case reply::not_modified:
+    return not_modified;
+  case reply::bad_request:
+    return bad_request;
+  case reply::unauthorized:
+    return unauthorized;
+  case reply::forbidden:
+    return forbidden;
+  case reply::not_found:
+    return not_found;
+  case reply::internal_server_error:
+    return internal_server_error;
+  case reply::not_implemented:
+    return not_implemented;
+  case reply::bad_gateway:
+    return bad_gateway;
+  case reply::service_unavailable:
+    return service_unavailable;
+  default:
+    return internal_server_error;
+  }
+}
+
+} // namespace stock_replies
+
+reply reply::stock_reply(reply::status_type status)
+{
+  reply rep;
+  rep.status = status;
+  rep.content = stock_replies::to_string(status);
+  rep.headers.resize(2);
+  rep.headers[0].name = "Content-Length";
+  rep.headers[0].value = boost::lexical_cast<std::string>(rep.content.size());
+  rep.headers[1].name = "Content-Type";
+  rep.headers[1].value = "text/html";
+  return rep;
+}
+
+} // namespace server2
+} // namespace http

doc/html/boost_asio/example/cpp03/http/server2/reply.hpp

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+//
+// reply.hpp
+// ~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef HTTP_SERVER2_REPLY_HPP
+#define HTTP_SERVER2_REPLY_HPP
+
+#include <string>
+#include <vector>
+#include <boost/asio.hpp>
+#include "header.hpp"
+
+namespace http {
+namespace server2 {
+
+/// A reply to be sent to a client.
+struct reply
+{
+  /// The status of the reply.
+  enum status_type
+  {
+    ok = 200,
+    created = 201,
+    accepted = 202,
+    no_content = 204,
+    multiple_choices = 300,
+    moved_permanently = 301,
+    moved_temporarily = 302,
+    not_modified = 304,
+    bad_request = 400,
+    unauthorized = 401,
+    forbidden = 403,
+    not_found = 404,
+    internal_server_error = 500,
+    not_implemented = 501,
+    bad_gateway = 502,
+    service_unavailable = 503
+  } status;
+
+  /// The headers to be included in the reply.
+  std::vector<header> headers;
+
+  /// The content to be sent in the reply.
+  std::string content;
+
+  /// Convert the reply into a vector of buffers. The buffers do not own the
+  /// underlying memory blocks, therefore the reply object must remain valid and
+  /// not be changed until the write operation has completed.
+  std::vector<boost::asio::const_buffer> to_buffers();
+
+  /// Get a stock reply.
+  static reply stock_reply(status_type status);
+};
+
+} // namespace server2
+} // namespace http
+
+#endif // HTTP_SERVER2_REPLY_HPP

doc/html/boost_asio/example/cpp03/http/server2/request.hpp

@@ -0,0 +1,34 @@
+//
+// request.hpp
+// ~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef HTTP_SERVER2_REQUEST_HPP
+#define HTTP_SERVER2_REQUEST_HPP
+
+#include <string>
+#include <vector>
+#include "header.hpp"
+
+namespace http {
+namespace server2 {
+
+/// A request received from a client.
+struct request
+{
+  std::string method;
+  std::string uri;
+  int http_version_major;
+  int http_version_minor;
+  std::vector<header> headers;
+};
+
+} // namespace server2
+} // namespace http
+
+#endif // HTTP_SERVER2_REQUEST_HPP

doc/html/boost_asio/example/cpp03/http/server2/request_handler.cpp

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+//
+// request_handler.cpp
+// ~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include "request_handler.hpp"
+#include <fstream>
+#include <sstream>
+#include <string>
+#include <boost/lexical_cast.hpp>
+#include "mime_types.hpp"
+#include "reply.hpp"
+#include "request.hpp"
+
+namespace http {
+namespace server2 {
+
+request_handler::request_handler(const std::string& doc_root)
+  : doc_root_(doc_root)
+{
+}
+
+void request_handler::handle_request(const request& req, reply& rep)
+{
+  // Decode url to path.
+  std::string request_path;
+  if (!url_decode(req.uri, request_path))
+  {
+    rep = reply::stock_reply(reply::bad_request);
+    return;
+  }
+
+  // Request path must be absolute and not contain "..".
+  if (request_path.empty() || request_path[0] != '/'
+      || request_path.find("..") != std::string::npos)
+  {
+    rep = reply::stock_reply(reply::bad_request);
+    return;
+  }
+
+  // If path ends in slash (i.e. is a directory) then add "index.html".
+  if (request_path[request_path.size() - 1] == '/')
+  {
+    request_path += "index.html";
+  }
+
+  // Determine the file extension.
+  std::size_t last_slash_pos = request_path.find_last_of("/");
+  std::size_t last_dot_pos = request_path.find_last_of(".");
+  std::string extension;
+  if (last_dot_pos != std::string::npos && last_dot_pos > last_slash_pos)
+  {
+    extension = request_path.substr(last_dot_pos + 1);
+  }
+
+  // Open the file to send back.
+  std::string full_path = doc_root_ + request_path;
+  std::ifstream is(full_path.c_str(), std::ios::in | std::ios::binary);
+  if (!is)
+  {
+    rep = reply::stock_reply(reply::not_found);
+    return;
+  }
+
+  // Fill out the reply to be sent to the client.
+  rep.status = reply::ok;
+  char buf[512];
+  while (is.read(buf, sizeof(buf)).gcount() > 0)
+    rep.content.append(buf, is.gcount());
+  rep.headers.resize(2);
+  rep.headers[0].name = "Content-Length";
+  rep.headers[0].value = boost::lexical_cast<std::string>(rep.content.size());
+  rep.headers[1].name = "Content-Type";
+  rep.headers[1].value = mime_types::extension_to_type(extension);
+}
+
+bool request_handler::url_decode(const std::string& in, std::string& out)
+{
+  out.clear();
+  out.reserve(in.size());
+  for (std::size_t i = 0; i < in.size(); ++i)
+  {
+    if (in[i] == '%')
+    {
+      if (i + 3 <= in.size())
+      {
+        int value = 0;
+        std::istringstream is(in.substr(i + 1, 2));
+        if (is >> std::hex >> value)
+        {
+          out += static_cast<char>(value);
+          i += 2;
+        }
+        else
+        {
+          return false;
+        }
+      }
+      else
+      {
+        return false;
+      }
+    }
+    else if (in[i] == '+')
+    {
+      out += ' ';
+    }
+    else
+    {
+      out += in[i];
+    }
+  }
+  return true;
+}
+
+} // namespace server2
+} // namespace http

doc/html/boost_asio/example/cpp03/http/server2/request_handler.hpp

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+//
+// request_handler.hpp
+// ~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef HTTP_SERVER2_REQUEST_HANDLER_HPP
+#define HTTP_SERVER2_REQUEST_HANDLER_HPP
+
+#include <string>
+#include <boost/noncopyable.hpp>
+
+namespace http {
+namespace server2 {
+
+struct reply;
+struct request;
+
+/// The common handler for all incoming requests.
+class request_handler
+  : private boost::noncopyable
+{
+public:
+  /// Construct with a directory containing files to be served.
+  explicit request_handler(const std::string& doc_root);
+
+  /// Handle a request and produce a reply.
+  void handle_request(const request& req, reply& rep);
+
+private:
+  /// The directory containing the files to be served.
+  std::string doc_root_;
+
+  /// Perform URL-decoding on a string. Returns false if the encoding was
+  /// invalid.
+  static bool url_decode(const std::string& in, std::string& out);
+};
+
+} // namespace server2
+} // namespace http
+
+#endif // HTTP_SERVER2_REQUEST_HANDLER_HPP

doc/html/boost_asio/example/cpp03/http/server2/request_parser.cpp

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+//
+// request_parser.cpp
+// ~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include "request_parser.hpp"
+#include "request.hpp"
+
+namespace http {
+namespace server2 {
+
+request_parser::request_parser()
+  : state_(method_start)
+{
+}
+
+void request_parser::reset()
+{
+  state_ = method_start;
+}
+
+boost::tribool request_parser::consume(request& req, char input)
+{
+  switch (state_)
+  {
+  case method_start:
+    if (!is_char(input) || is_ctl(input) || is_tspecial(input))
+    {
+      return false;
+    }
+    else
+    {
+      state_ = method;
+      req.method.push_back(input);
+      return boost::indeterminate;
+    }
+  case method:
+    if (input == ' ')
+    {
+      state_ = uri;
+      return boost::indeterminate;
+    }
+    else if (!is_char(input) || is_ctl(input) || is_tspecial(input))
+    {
+      return false;
+    }
+    else
+    {
+      req.method.push_back(input);
+      return boost::indeterminate;
+    }
+  case uri:
+    if (input == ' ')
+    {
+      state_ = http_version_h;
+      return boost::indeterminate;
+    }
+    else if (is_ctl(input))
+    {
+      return false;
+    }
+    else
+    {
+      req.uri.push_back(input);
+      return boost::indeterminate;
+    }
+  case http_version_h:
+    if (input == 'H')
+    {
+      state_ = http_version_t_1;
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case http_version_t_1:
+    if (input == 'T')
+    {
+      state_ = http_version_t_2;
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case http_version_t_2:
+    if (input == 'T')
+    {
+      state_ = http_version_p;
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case http_version_p:
+    if (input == 'P')
+    {
+      state_ = http_version_slash;
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case http_version_slash:
+    if (input == '/')
+    {
+      req.http_version_major = 0;
+      req.http_version_minor = 0;
+      state_ = http_version_major_start;
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case http_version_major_start:
+    if (is_digit(input))
+    {
+      req.http_version_major = req.http_version_major * 10 + input - '0';
+      state_ = http_version_major;
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case http_version_major:
+    if (input == '.')
+    {
+      state_ = http_version_minor_start;
+      return boost::indeterminate;
+    }
+    else if (is_digit(input))
+    {
+      req.http_version_major = req.http_version_major * 10 + input - '0';
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case http_version_minor_start:
+    if (is_digit(input))
+    {
+      req.http_version_minor = req.http_version_minor * 10 + input - '0';
+      state_ = http_version_minor;
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case http_version_minor:
+    if (input == '\r')
+    {
+      state_ = expecting_newline_1;
+      return boost::indeterminate;
+    }
+    else if (is_digit(input))
+    {
+      req.http_version_minor = req.http_version_minor * 10 + input - '0';
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case expecting_newline_1:
+    if (input == '\n')
+    {
+      state_ = header_line_start;
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case header_line_start:
+    if (input == '\r')
+    {
+      state_ = expecting_newline_3;
+      return boost::indeterminate;
+    }
+    else if (!req.headers.empty() && (input == ' ' || input == '\t'))
+    {
+      state_ = header_lws;
+      return boost::indeterminate;
+    }
+    else if (!is_char(input) || is_ctl(input) || is_tspecial(input))
+    {
+      return false;
+    }
+    else
+    {
+      req.headers.push_back(header());
+      req.headers.back().name.push_back(input);
+      state_ = header_name;
+      return boost::indeterminate;
+    }
+  case header_lws:
+    if (input == '\r')
+    {
+      state_ = expecting_newline_2;
+      return boost::indeterminate;
+    }
+    else if (input == ' ' || input == '\t')
+    {
+      return boost::indeterminate;
+    }
+    else if (is_ctl(input))
+    {
+      return false;
+    }
+    else
+    {
+      state_ = header_value;
+      req.headers.back().value.push_back(input);
+      return boost::indeterminate;
+    }
+  case header_name:
+    if (input == ':')
+    {
+      state_ = space_before_header_value;
+      return boost::indeterminate;
+    }
+    else if (!is_char(input) || is_ctl(input) || is_tspecial(input))
+    {
+      return false;
+    }
+    else
+    {
+      req.headers.back().name.push_back(input);
+      return boost::indeterminate;
+    }
+  case space_before_header_value:
+    if (input == ' ')
+    {
+      state_ = header_value;
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case header_value:
+    if (input == '\r')
+    {
+      state_ = expecting_newline_2;
+      return boost::indeterminate;
+    }
+    else if (is_ctl(input))
+    {
+      return false;
+    }
+    else
+    {
+      req.headers.back().value.push_back(input);
+      return boost::indeterminate;
+    }
+  case expecting_newline_2:
+    if (input == '\n')
+    {
+      state_ = header_line_start;
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case expecting_newline_3:
+    return (input == '\n');
+  default:
+    return false;
+  }
+}
+
+bool request_parser::is_char(int c)
+{
+  return c >= 0 && c <= 127;
+}
+
+bool request_parser::is_ctl(int c)
+{
+  return (c >= 0 && c <= 31) || (c == 127);
+}
+
+bool request_parser::is_tspecial(int c)
+{
+  switch (c)
+  {
+  case '(': case ')': case '<': case '>': case '@':
+  case ',': case ';': case ':': case '\\': case '"':
+  case '/': case '[': case ']': case '?': case '=':
+  case '{': case '}': case ' ': case '\t':
+    return true;
+  default:
+    return false;
+  }
+}
+
+bool request_parser::is_digit(int c)
+{
+  return c >= '0' && c <= '9';
+}
+
+} // namespace server2
+} // namespace http

doc/html/boost_asio/example/cpp03/http/server2/request_parser.hpp

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+//
+// request_parser.hpp
+// ~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef HTTP_SERVER2_REQUEST_PARSER_HPP
+#define HTTP_SERVER2_REQUEST_PARSER_HPP
+
+#include <boost/logic/tribool.hpp>
+#include <boost/tuple/tuple.hpp>
+
+namespace http {
+namespace server2 {
+
+struct request;
+
+/// Parser for incoming requests.
+class request_parser
+{
+public:
+  /// Construct ready to parse the request method.
+  request_parser();
+
+  /// Reset to initial parser state.
+  void reset();
+
+  /// Parse some data. The tribool return value is true when a complete request
+  /// has been parsed, false if the data is invalid, indeterminate when more
+  /// data is required. The InputIterator return value indicates how much of the
+  /// input has been consumed.
+  template <typename InputIterator>
+  boost::tuple<boost::tribool, InputIterator> parse(request& req,
+      InputIterator begin, InputIterator end)
+  {
+    while (begin != end)
+    {
+      boost::tribool result = consume(req, *begin++);
+      if (result || !result)
+        return boost::make_tuple(result, begin);
+    }
+    boost::tribool result = boost::indeterminate;
+    return boost::make_tuple(result, begin);
+  }
+
+private:
+  /// Handle the next character of input.
+  boost::tribool consume(request& req, char input);
+
+  /// Check if a byte is an HTTP character.
+  static bool is_char(int c);
+
+  /// Check if a byte is an HTTP control character.
+  static bool is_ctl(int c);
+
+  /// Check if a byte is defined as an HTTP tspecial character.
+  static bool is_tspecial(int c);
+
+  /// Check if a byte is a digit.
+  static bool is_digit(int c);
+
+  /// The current state of the parser.
+  enum state
+  {
+    method_start,
+    method,
+    uri,
+    http_version_h,
+    http_version_t_1,
+    http_version_t_2,
+    http_version_p,
+    http_version_slash,
+    http_version_major_start,
+    http_version_major,
+    http_version_minor_start,
+    http_version_minor,
+    expecting_newline_1,
+    header_line_start,
+    header_lws,
+    header_name,
+    space_before_header_value,
+    header_value,
+    expecting_newline_2,
+    expecting_newline_3
+  } state_;
+};
+
+} // namespace server2
+} // namespace http
+
+#endif // HTTP_SERVER2_REQUEST_PARSER_HPP

doc/html/boost_asio/example/cpp03/http/server2/server.cpp

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+//
+// server.cpp
+// ~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include "server.hpp"
+#include <boost/bind/bind.hpp>
+
+namespace http {
+namespace server2 {
+
+server::server(const std::string& address, const std::string& port,
+    const std::string& doc_root, std::size_t io_context_pool_size)
+  : io_context_pool_(io_context_pool_size),
+    signals_(io_context_pool_.get_io_context()),
+    acceptor_(io_context_pool_.get_io_context()),
+    new_connection_(),
+    request_handler_(doc_root)
+{
+  // Register to handle the signals that indicate when the server should exit.
+  // It is safe to register for the same signal multiple times in a program,
+  // provided all registration for the specified signal is made through Asio.
+  signals_.add(SIGINT);
+  signals_.add(SIGTERM);
+#if defined(SIGQUIT)
+  signals_.add(SIGQUIT);
+#endif // defined(SIGQUIT)
+  signals_.async_wait(boost::bind(&server::handle_stop, this));
+
+  // Open the acceptor with the option to reuse the address (i.e. SO_REUSEADDR).
+  boost::asio::ip::tcp::resolver resolver(acceptor_.get_executor());
+  boost::asio::ip::tcp::endpoint endpoint =
+    *resolver.resolve(address, port).begin();
+  acceptor_.open(endpoint.protocol());
+  acceptor_.set_option(boost::asio::ip::tcp::acceptor::reuse_address(true));
+  acceptor_.bind(endpoint);
+  acceptor_.listen();
+
+  start_accept();
+}
+
+void server::run()
+{
+  io_context_pool_.run();
+}
+
+void server::start_accept()
+{
+  new_connection_.reset(new connection(
+        io_context_pool_.get_io_context(), request_handler_));
+  acceptor_.async_accept(new_connection_->socket(),
+      boost::bind(&server::handle_accept, this,
+        boost::asio::placeholders::error));
+}
+
+void server::handle_accept(const boost::system::error_code& e)
+{
+  if (!e)
+  {
+    new_connection_->start();
+  }
+
+  start_accept();
+}
+
+void server::handle_stop()
+{
+  io_context_pool_.stop();
+}
+
+} // namespace server2
+} // namespace http

doc/html/boost_asio/example/cpp03/http/server2/server.hpp

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+//
+// server.hpp
+// ~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef HTTP_SERVER2_SERVER_HPP
+#define HTTP_SERVER2_SERVER_HPP
+
+#include <boost/asio.hpp>
+#include <string>
+#include <vector>
+#include <boost/noncopyable.hpp>
+#include <boost/shared_ptr.hpp>
+#include "connection.hpp"
+#include "io_context_pool.hpp"
+#include "request_handler.hpp"
+
+namespace http {
+namespace server2 {
+
+/// The top-level class of the HTTP server.
+class server
+  : private boost::noncopyable
+{
+public:
+  /// Construct the server to listen on the specified TCP address and port, and
+  /// serve up files from the given directory.
+  explicit server(const std::string& address, const std::string& port,
+      const std::string& doc_root, std::size_t io_context_pool_size);
+
+  /// Run the server's io_context loop.
+  void run();
+
+private:
+  /// Initiate an asynchronous accept operation.
+  void start_accept();
+
+  /// Handle completion of an asynchronous accept operation.
+  void handle_accept(const boost::system::error_code& e);
+
+  /// Handle a request to stop the server.
+  void handle_stop();
+
+  /// The pool of io_context objects used to perform asynchronous operations.
+  io_context_pool io_context_pool_;
+
+  /// The signal_set is used to register for process termination notifications.
+  boost::asio::signal_set signals_;
+
+  /// Acceptor used to listen for incoming connections.
+  boost::asio::ip::tcp::acceptor acceptor_;
+
+  /// The next connection to be accepted.
+  connection_ptr new_connection_;
+
+  /// The handler for all incoming requests.
+  request_handler request_handler_;
+};
+
+} // namespace server2
+} // namespace http
+
+#endif // HTTP_SERVER2_SERVER_HPP

doc/html/boost_asio/example/cpp03/http/server3/connection.cpp

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+//
+// connection.cpp
+// ~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include "connection.hpp"
+#include <vector>
+#include <boost/bind/bind.hpp>
+#include "request_handler.hpp"
+
+namespace http {
+namespace server3 {
+
+connection::connection(boost::asio::io_context& io_context,
+    request_handler& handler)
+  : strand_(boost::asio::make_strand(io_context)),
+    socket_(strand_),
+    request_handler_(handler)
+{
+}
+
+boost::asio::ip::tcp::socket& connection::socket()
+{
+  return socket_;
+}
+
+void connection::start()
+{
+  socket_.async_read_some(boost::asio::buffer(buffer_),
+      boost::bind(&connection::handle_read, shared_from_this(),
+        boost::asio::placeholders::error,
+        boost::asio::placeholders::bytes_transferred));
+}
+
+void connection::handle_read(const boost::system::error_code& e,
+    std::size_t bytes_transferred)
+{
+  if (!e)
+  {
+    boost::tribool result;
+    boost::tie(result, boost::tuples::ignore) = request_parser_.parse(
+        request_, buffer_.data(), buffer_.data() + bytes_transferred);
+
+    if (result)
+    {
+      request_handler_.handle_request(request_, reply_);
+      boost::asio::async_write(socket_, reply_.to_buffers(),
+          boost::bind(&connection::handle_write, shared_from_this(),
+            boost::asio::placeholders::error));
+    }
+    else if (!result)
+    {
+      reply_ = reply::stock_reply(reply::bad_request);
+      boost::asio::async_write(socket_, reply_.to_buffers(),
+          boost::bind(&connection::handle_write, shared_from_this(),
+            boost::asio::placeholders::error));
+    }
+    else
+    {
+      socket_.async_read_some(boost::asio::buffer(buffer_),
+          boost::bind(&connection::handle_read, shared_from_this(),
+            boost::asio::placeholders::error,
+            boost::asio::placeholders::bytes_transferred));
+    }
+  }
+
+  // If an error occurs then no new asynchronous operations are started. This
+  // means that all shared_ptr references to the connection object will
+  // disappear and the object will be destroyed automatically after this
+  // handler returns. The connection class's destructor closes the socket.
+}
+
+void connection::handle_write(const boost::system::error_code& e)
+{
+  if (!e)
+  {
+    // Initiate graceful connection closure.
+    boost::system::error_code ignored_ec;
+    socket_.shutdown(boost::asio::ip::tcp::socket::shutdown_both, ignored_ec);
+  }
+
+  // No new asynchronous operations are started. This means that all shared_ptr
+  // references to the connection object will disappear and the object will be
+  // destroyed automatically after this handler returns. The connection class's
+  // destructor closes the socket.
+}
+
+} // namespace server3
+} // namespace http

doc/html/boost_asio/example/cpp03/http/server3/connection.hpp

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+//
+// connection.hpp
+// ~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef HTTP_SERVER3_CONNECTION_HPP
+#define HTTP_SERVER3_CONNECTION_HPP
+
+#include <boost/asio.hpp>
+#include <boost/array.hpp>
+#include <boost/noncopyable.hpp>
+#include <boost/shared_ptr.hpp>
+#include <boost/enable_shared_from_this.hpp>
+#include "reply.hpp"
+#include "request.hpp"
+#include "request_handler.hpp"
+#include "request_parser.hpp"
+
+namespace http {
+namespace server3 {
+
+/// Represents a single connection from a client.
+class connection
+  : public boost::enable_shared_from_this<connection>,
+    private boost::noncopyable
+{
+public:
+  /// Construct a connection with the given io_context.
+  explicit connection(boost::asio::io_context& io_context,
+      request_handler& handler);
+
+  /// Get the socket associated with the connection.
+  boost::asio::ip::tcp::socket& socket();
+
+  /// Start the first asynchronous operation for the connection.
+  void start();
+
+private:
+  /// Handle completion of a read operation.
+  void handle_read(const boost::system::error_code& e,
+      std::size_t bytes_transferred);
+
+  /// Handle completion of a write operation.
+  void handle_write(const boost::system::error_code& e);
+
+  /// Strand to ensure the connection's handlers are not called concurrently.
+  boost::asio::strand<boost::asio::io_context::executor_type> strand_;
+
+  /// Socket for the connection.
+  boost::asio::ip::tcp::socket socket_;
+
+  /// The handler used to process the incoming request.
+  request_handler& request_handler_;
+
+  /// Buffer for incoming data.
+  boost::array<char, 8192> buffer_;
+
+  /// The incoming request.
+  request request_;
+
+  /// The parser for the incoming request.
+  request_parser request_parser_;
+
+  /// The reply to be sent back to the client.
+  reply reply_;
+};
+
+typedef boost::shared_ptr<connection> connection_ptr;
+
+} // namespace server3
+} // namespace http
+
+#endif // HTTP_SERVER3_CONNECTION_HPP

doc/html/boost_asio/example/cpp03/http/server3/header.hpp

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+//
+// header.hpp
+// ~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef HTTP_SERVER3_HEADER_HPP
+#define HTTP_SERVER3_HEADER_HPP
+
+#include <string>
+
+namespace http {
+namespace server3 {
+
+struct header
+{
+  std::string name;
+  std::string value;
+};
+
+} // namespace server3
+} // namespace http
+
+#endif // HTTP_SERVER3_HEADER_HPP

doc/html/boost_asio/example/cpp03/http/server3/main.cpp

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+//
+// main.cpp
+// ~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <iostream>
+#include <string>
+#include <boost/asio.hpp>
+#include <boost/bind/bind.hpp>
+#include <boost/lexical_cast.hpp>
+#include "server.hpp"
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    // Check command line arguments.
+    if (argc != 5)
+    {
+      std::cerr << "Usage: http_server <address> <port> <threads> <doc_root>\n";
+      std::cerr << "  For IPv4, try:\n";
+      std::cerr << "    receiver 0.0.0.0 80 1 .\n";
+      std::cerr << "  For IPv6, try:\n";
+      std::cerr << "    receiver 0::0 80 1 .\n";
+      return 1;
+    }
+
+    // Initialise the server.
+    std::size_t num_threads = boost::lexical_cast<std::size_t>(argv[3]);
+    http::server3::server s(argv[1], argv[2], argv[4], num_threads);
+
+    // Run the server until stopped.
+    s.run();
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << "exception: " << e.what() << "\n";
+  }
+
+  return 0;
+}

doc/html/boost_asio/example/cpp03/http/server3/mime_types.cpp

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+//
+// mime_types.cpp
+// ~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include "mime_types.hpp"
+
+namespace http {
+namespace server3 {
+namespace mime_types {
+
+struct mapping
+{
+  const char* extension;
+  const char* mime_type;
+} mappings[] =
+{
+  { "gif", "image/gif" },
+  { "htm", "text/html" },
+  { "html", "text/html" },
+  { "jpg", "image/jpeg" },
+  { "png", "image/png" },
+  { 0, 0 } // Marks end of list.
+};
+
+std::string extension_to_type(const std::string& extension)
+{
+  for (mapping* m = mappings; m->extension; ++m)
+  {
+    if (m->extension == extension)
+    {
+      return m->mime_type;
+    }
+  }
+
+  return "text/plain";
+}
+
+} // namespace mime_types
+} // namespace server3
+} // namespace http

doc/html/boost_asio/example/cpp03/http/server3/mime_types.hpp

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+//
+// mime_types.hpp
+// ~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef HTTP_SERVER3_MIME_TYPES_HPP
+#define HTTP_SERVER3_MIME_TYPES_HPP
+
+#include <string>
+
+namespace http {
+namespace server3 {
+namespace mime_types {
+
+/// Convert a file extension into a MIME type.
+std::string extension_to_type(const std::string& extension);
+
+} // namespace mime_types
+} // namespace server3
+} // namespace http
+
+#endif // HTTP_SERVER3_MIME_TYPES_HPP

doc/html/boost_asio/example/cpp03/http/server3/reply.cpp

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+//
+// reply.cpp
+// ~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include "reply.hpp"
+#include <string>
+#include <boost/lexical_cast.hpp>
+
+namespace http {
+namespace server3 {
+
+namespace status_strings {
+
+const std::string ok =
+  "HTTP/1.0 200 OK\r\n";
+const std::string created =
+  "HTTP/1.0 201 Created\r\n";
+const std::string accepted =
+  "HTTP/1.0 202 Accepted\r\n";
+const std::string no_content =
+  "HTTP/1.0 204 No Content\r\n";
+const std::string multiple_choices =
+  "HTTP/1.0 300 Multiple Choices\r\n";
+const std::string moved_permanently =
+  "HTTP/1.0 301 Moved Permanently\r\n";
+const std::string moved_temporarily =
+  "HTTP/1.0 302 Moved Temporarily\r\n";
+const std::string not_modified =
+  "HTTP/1.0 304 Not Modified\r\n";
+const std::string bad_request =
+  "HTTP/1.0 400 Bad Request\r\n";
+const std::string unauthorized =
+  "HTTP/1.0 401 Unauthorized\r\n";
+const std::string forbidden =
+  "HTTP/1.0 403 Forbidden\r\n";
+const std::string not_found =
+  "HTTP/1.0 404 Not Found\r\n";
+const std::string internal_server_error =
+  "HTTP/1.0 500 Internal Server Error\r\n";
+const std::string not_implemented =
+  "HTTP/1.0 501 Not Implemented\r\n";
+const std::string bad_gateway =
+  "HTTP/1.0 502 Bad Gateway\r\n";
+const std::string service_unavailable =
+  "HTTP/1.0 503 Service Unavailable\r\n";
+
+boost::asio::const_buffer to_buffer(reply::status_type status)
+{
+  switch (status)
+  {
+  case reply::ok:
+    return boost::asio::buffer(ok);
+  case reply::created:
+    return boost::asio::buffer(created);
+  case reply::accepted:
+    return boost::asio::buffer(accepted);
+  case reply::no_content:
+    return boost::asio::buffer(no_content);
+  case reply::multiple_choices:
+    return boost::asio::buffer(multiple_choices);
+  case reply::moved_permanently:
+    return boost::asio::buffer(moved_permanently);
+  case reply::moved_temporarily:
+    return boost::asio::buffer(moved_temporarily);
+  case reply::not_modified:
+    return boost::asio::buffer(not_modified);
+  case reply::bad_request:
+    return boost::asio::buffer(bad_request);
+  case reply::unauthorized:
+    return boost::asio::buffer(unauthorized);
+  case reply::forbidden:
+    return boost::asio::buffer(forbidden);
+  case reply::not_found:
+    return boost::asio::buffer(not_found);
+  case reply::internal_server_error:
+    return boost::asio::buffer(internal_server_error);
+  case reply::not_implemented:
+    return boost::asio::buffer(not_implemented);
+  case reply::bad_gateway:
+    return boost::asio::buffer(bad_gateway);
+  case reply::service_unavailable:
+    return boost::asio::buffer(service_unavailable);
+  default:
+    return boost::asio::buffer(internal_server_error);
+  }
+}
+
+} // namespace status_strings
+
+namespace misc_strings {
+
+const char name_value_separator[] = { ':', ' ' };
+const char crlf[] = { '\r', '\n' };
+
+} // namespace misc_strings
+
+std::vector<boost::asio::const_buffer> reply::to_buffers()
+{
+  std::vector<boost::asio::const_buffer> buffers;
+  buffers.push_back(status_strings::to_buffer(status));
+  for (std::size_t i = 0; i < headers.size(); ++i)
+  {
+    header& h = headers[i];
+    buffers.push_back(boost::asio::buffer(h.name));
+    buffers.push_back(boost::asio::buffer(misc_strings::name_value_separator));
+    buffers.push_back(boost::asio::buffer(h.value));
+    buffers.push_back(boost::asio::buffer(misc_strings::crlf));
+  }
+  buffers.push_back(boost::asio::buffer(misc_strings::crlf));
+  buffers.push_back(boost::asio::buffer(content));
+  return buffers;
+}
+
+namespace stock_replies {
+
+const char ok[] = "";
+const char created[] =
+  "<html>"
+  "<head><title>Created</title></head>"
+  "<body><h1>201 Created</h1></body>"
+  "</html>";
+const char accepted[] =
+  "<html>"
+  "<head><title>Accepted</title></head>"
+  "<body><h1>202 Accepted</h1></body>"
+  "</html>";
+const char no_content[] =
+  "<html>"
+  "<head><title>No Content</title></head>"
+  "<body><h1>204 Content</h1></body>"
+  "</html>";
+const char multiple_choices[] =
+  "<html>"
+  "<head><title>Multiple Choices</title></head>"
+  "<body><h1>300 Multiple Choices</h1></body>"
+  "</html>";
+const char moved_permanently[] =
+  "<html>"
+  "<head><title>Moved Permanently</title></head>"
+  "<body><h1>301 Moved Permanently</h1></body>"
+  "</html>";
+const char moved_temporarily[] =
+  "<html>"
+  "<head><title>Moved Temporarily</title></head>"
+  "<body><h1>302 Moved Temporarily</h1></body>"
+  "</html>";
+const char not_modified[] =
+  "<html>"
+  "<head><title>Not Modified</title></head>"
+  "<body><h1>304 Not Modified</h1></body>"
+  "</html>";
+const char bad_request[] =
+  "<html>"
+  "<head><title>Bad Request</title></head>"
+  "<body><h1>400 Bad Request</h1></body>"
+  "</html>";
+const char unauthorized[] =
+  "<html>"
+  "<head><title>Unauthorized</title></head>"
+  "<body><h1>401 Unauthorized</h1></body>"
+  "</html>";
+const char forbidden[] =
+  "<html>"
+  "<head><title>Forbidden</title></head>"
+  "<body><h1>403 Forbidden</h1></body>"
+  "</html>";
+const char not_found[] =
+  "<html>"
+  "<head><title>Not Found</title></head>"
+  "<body><h1>404 Not Found</h1></body>"
+  "</html>";
+const char internal_server_error[] =
+  "<html>"
+  "<head><title>Internal Server Error</title></head>"
+  "<body><h1>500 Internal Server Error</h1></body>"
+  "</html>";
+const char not_implemented[] =
+  "<html>"
+  "<head><title>Not Implemented</title></head>"
+  "<body><h1>501 Not Implemented</h1></body>"
+  "</html>";
+const char bad_gateway[] =
+  "<html>"
+  "<head><title>Bad Gateway</title></head>"
+  "<body><h1>502 Bad Gateway</h1></body>"
+  "</html>";
+const char service_unavailable[] =
+  "<html>"
+  "<head><title>Service Unavailable</title></head>"
+  "<body><h1>503 Service Unavailable</h1></body>"
+  "</html>";
+
+std::string to_string(reply::status_type status)
+{
+  switch (status)
+  {
+  case reply::ok:
+    return ok;
+  case reply::created:
+    return created;
+  case reply::accepted:
+    return accepted;
+  case reply::no_content:
+    return no_content;
+  case reply::multiple_choices:
+    return multiple_choices;
+  case reply::moved_permanently:
+    return moved_permanently;
+  case reply::moved_temporarily:
+    return moved_temporarily;
+  case reply::not_modified:
+    return not_modified;
+  case reply::bad_request:
+    return bad_request;
+  case reply::unauthorized:
+    return unauthorized;
+  case reply::forbidden:
+    return forbidden;
+  case reply::not_found:
+    return not_found;
+  case reply::internal_server_error:
+    return internal_server_error;
+  case reply::not_implemented:
+    return not_implemented;
+  case reply::bad_gateway:
+    return bad_gateway;
+  case reply::service_unavailable:
+    return service_unavailable;
+  default:
+    return internal_server_error;
+  }
+}
+
+} // namespace stock_replies
+
+reply reply::stock_reply(reply::status_type status)
+{
+  reply rep;
+  rep.status = status;
+  rep.content = stock_replies::to_string(status);
+  rep.headers.resize(2);
+  rep.headers[0].name = "Content-Length";
+  rep.headers[0].value = boost::lexical_cast<std::string>(rep.content.size());
+  rep.headers[1].name = "Content-Type";
+  rep.headers[1].value = "text/html";
+  return rep;
+}
+
+} // namespace server3
+} // namespace http

doc/html/boost_asio/example/cpp03/http/server3/reply.hpp

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+//
+// reply.hpp
+// ~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef HTTP_SERVER3_REPLY_HPP
+#define HTTP_SERVER3_REPLY_HPP
+
+#include <string>
+#include <vector>
+#include <boost/asio.hpp>
+#include "header.hpp"
+
+namespace http {
+namespace server3 {
+
+/// A reply to be sent to a client.
+struct reply
+{
+  /// The status of the reply.
+  enum status_type
+  {
+    ok = 200,
+    created = 201,
+    accepted = 202,
+    no_content = 204,
+    multiple_choices = 300,
+    moved_permanently = 301,
+    moved_temporarily = 302,
+    not_modified = 304,
+    bad_request = 400,
+    unauthorized = 401,
+    forbidden = 403,
+    not_found = 404,
+    internal_server_error = 500,
+    not_implemented = 501,
+    bad_gateway = 502,
+    service_unavailable = 503
+  } status;
+
+  /// The headers to be included in the reply.
+  std::vector<header> headers;
+
+  /// The content to be sent in the reply.
+  std::string content;
+
+  /// Convert the reply into a vector of buffers. The buffers do not own the
+  /// underlying memory blocks, therefore the reply object must remain valid and
+  /// not be changed until the write operation has completed.
+  std::vector<boost::asio::const_buffer> to_buffers();
+
+  /// Get a stock reply.
+  static reply stock_reply(status_type status);
+};
+
+} // namespace server3
+} // namespace http
+
+#endif // HTTP_SERVER3_REPLY_HPP

doc/html/boost_asio/example/cpp03/http/server3/request.hpp

@@ -0,0 +1,34 @@
+//
+// request.hpp
+// ~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef HTTP_SERVER3_REQUEST_HPP
+#define HTTP_SERVER3_REQUEST_HPP
+
+#include <string>
+#include <vector>
+#include "header.hpp"
+
+namespace http {
+namespace server3 {
+
+/// A request received from a client.
+struct request
+{
+  std::string method;
+  std::string uri;
+  int http_version_major;
+  int http_version_minor;
+  std::vector<header> headers;
+};
+
+} // namespace server3
+} // namespace http
+
+#endif // HTTP_SERVER3_REQUEST_HPP

doc/html/boost_asio/example/cpp03/http/server3/request_handler.cpp

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+//
+// request_handler.cpp
+// ~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include "request_handler.hpp"
+#include <fstream>
+#include <sstream>
+#include <string>
+#include <boost/lexical_cast.hpp>
+#include "mime_types.hpp"
+#include "reply.hpp"
+#include "request.hpp"
+
+namespace http {
+namespace server3 {
+
+request_handler::request_handler(const std::string& doc_root)
+  : doc_root_(doc_root)
+{
+}
+
+void request_handler::handle_request(const request& req, reply& rep)
+{
+  // Decode url to path.
+  std::string request_path;
+  if (!url_decode(req.uri, request_path))
+  {
+    rep = reply::stock_reply(reply::bad_request);
+    return;
+  }
+
+  // Request path must be absolute and not contain "..".
+  if (request_path.empty() || request_path[0] != '/'
+      || request_path.find("..") != std::string::npos)
+  {
+    rep = reply::stock_reply(reply::bad_request);
+    return;
+  }
+
+  // If path ends in slash (i.e. is a directory) then add "index.html".
+  if (request_path[request_path.size() - 1] == '/')
+  {
+    request_path += "index.html";
+  }
+
+  // Determine the file extension.
+  std::size_t last_slash_pos = request_path.find_last_of("/");
+  std::size_t last_dot_pos = request_path.find_last_of(".");
+  std::string extension;
+  if (last_dot_pos != std::string::npos && last_dot_pos > last_slash_pos)
+  {
+    extension = request_path.substr(last_dot_pos + 1);
+  }
+
+  // Open the file to send back.
+  std::string full_path = doc_root_ + request_path;
+  std::ifstream is(full_path.c_str(), std::ios::in | std::ios::binary);
+  if (!is)
+  {
+    rep = reply::stock_reply(reply::not_found);
+    return;
+  }
+
+  // Fill out the reply to be sent to the client.
+  rep.status = reply::ok;
+  char buf[512];
+  while (is.read(buf, sizeof(buf)).gcount() > 0)
+    rep.content.append(buf, is.gcount());
+  rep.headers.resize(2);
+  rep.headers[0].name = "Content-Length";
+  rep.headers[0].value = boost::lexical_cast<std::string>(rep.content.size());
+  rep.headers[1].name = "Content-Type";
+  rep.headers[1].value = mime_types::extension_to_type(extension);
+}
+
+bool request_handler::url_decode(const std::string& in, std::string& out)
+{
+  out.clear();
+  out.reserve(in.size());
+  for (std::size_t i = 0; i < in.size(); ++i)
+  {
+    if (in[i] == '%')
+    {
+      if (i + 3 <= in.size())
+      {
+        int value = 0;
+        std::istringstream is(in.substr(i + 1, 2));
+        if (is >> std::hex >> value)
+        {
+          out += static_cast<char>(value);
+          i += 2;
+        }
+        else
+        {
+          return false;
+        }
+      }
+      else
+      {
+        return false;
+      }
+    }
+    else if (in[i] == '+')
+    {
+      out += ' ';
+    }
+    else
+    {
+      out += in[i];
+    }
+  }
+  return true;
+}
+
+} // namespace server3
+} // namespace http

doc/html/boost_asio/example/cpp03/http/server3/request_handler.hpp

@@ -0,0 +1,46 @@
+//
+// request_handler.hpp
+// ~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef HTTP_SERVER3_REQUEST_HANDLER_HPP
+#define HTTP_SERVER3_REQUEST_HANDLER_HPP
+
+#include <string>
+#include <boost/noncopyable.hpp>
+
+namespace http {
+namespace server3 {
+
+struct reply;
+struct request;
+
+/// The common handler for all incoming requests.
+class request_handler
+  : private boost::noncopyable
+{
+public:
+  /// Construct with a directory containing files to be served.
+  explicit request_handler(const std::string& doc_root);
+
+  /// Handle a request and produce a reply.
+  void handle_request(const request& req, reply& rep);
+
+private:
+  /// The directory containing the files to be served.
+  std::string doc_root_;
+
+  /// Perform URL-decoding on a string. Returns false if the encoding was
+  /// invalid.
+  static bool url_decode(const std::string& in, std::string& out);
+};
+
+} // namespace server3
+} // namespace http
+
+#endif // HTTP_SERVER3_REQUEST_HANDLER_HPP

doc/html/boost_asio/example/cpp03/http/server3/request_parser.cpp

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+//
+// request_parser.cpp
+// ~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include "request_parser.hpp"
+#include "request.hpp"
+
+namespace http {
+namespace server3 {
+
+request_parser::request_parser()
+  : state_(method_start)
+{
+}
+
+void request_parser::reset()
+{
+  state_ = method_start;
+}
+
+boost::tribool request_parser::consume(request& req, char input)
+{
+  switch (state_)
+  {
+  case method_start:
+    if (!is_char(input) || is_ctl(input) || is_tspecial(input))
+    {
+      return false;
+    }
+    else
+    {
+      state_ = method;
+      req.method.push_back(input);
+      return boost::indeterminate;
+    }
+  case method:
+    if (input == ' ')
+    {
+      state_ = uri;
+      return boost::indeterminate;
+    }
+    else if (!is_char(input) || is_ctl(input) || is_tspecial(input))
+    {
+      return false;
+    }
+    else
+    {
+      req.method.push_back(input);
+      return boost::indeterminate;
+    }
+  case uri:
+    if (input == ' ')
+    {
+      state_ = http_version_h;
+      return boost::indeterminate;
+    }
+    else if (is_ctl(input))
+    {
+      return false;
+    }
+    else
+    {
+      req.uri.push_back(input);
+      return boost::indeterminate;
+    }
+  case http_version_h:
+    if (input == 'H')
+    {
+      state_ = http_version_t_1;
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case http_version_t_1:
+    if (input == 'T')
+    {
+      state_ = http_version_t_2;
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case http_version_t_2:
+    if (input == 'T')
+    {
+      state_ = http_version_p;
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case http_version_p:
+    if (input == 'P')
+    {
+      state_ = http_version_slash;
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case http_version_slash:
+    if (input == '/')
+    {
+      req.http_version_major = 0;
+      req.http_version_minor = 0;
+      state_ = http_version_major_start;
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case http_version_major_start:
+    if (is_digit(input))
+    {
+      req.http_version_major = req.http_version_major * 10 + input - '0';
+      state_ = http_version_major;
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case http_version_major:
+    if (input == '.')
+    {
+      state_ = http_version_minor_start;
+      return boost::indeterminate;
+    }
+    else if (is_digit(input))
+    {
+      req.http_version_major = req.http_version_major * 10 + input - '0';
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case http_version_minor_start:
+    if (is_digit(input))
+    {
+      req.http_version_minor = req.http_version_minor * 10 + input - '0';
+      state_ = http_version_minor;
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case http_version_minor:
+    if (input == '\r')
+    {
+      state_ = expecting_newline_1;
+      return boost::indeterminate;
+    }
+    else if (is_digit(input))
+    {
+      req.http_version_minor = req.http_version_minor * 10 + input - '0';
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case expecting_newline_1:
+    if (input == '\n')
+    {
+      state_ = header_line_start;
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case header_line_start:
+    if (input == '\r')
+    {
+      state_ = expecting_newline_3;
+      return boost::indeterminate;
+    }
+    else if (!req.headers.empty() && (input == ' ' || input == '\t'))
+    {
+      state_ = header_lws;
+      return boost::indeterminate;
+    }
+    else if (!is_char(input) || is_ctl(input) || is_tspecial(input))
+    {
+      return false;
+    }
+    else
+    {
+      req.headers.push_back(header());
+      req.headers.back().name.push_back(input);
+      state_ = header_name;
+      return boost::indeterminate;
+    }
+  case header_lws:
+    if (input == '\r')
+    {
+      state_ = expecting_newline_2;
+      return boost::indeterminate;
+    }
+    else if (input == ' ' || input == '\t')
+    {
+      return boost::indeterminate;
+    }
+    else if (is_ctl(input))
+    {
+      return false;
+    }
+    else
+    {
+      state_ = header_value;
+      req.headers.back().value.push_back(input);
+      return boost::indeterminate;
+    }
+  case header_name:
+    if (input == ':')
+    {
+      state_ = space_before_header_value;
+      return boost::indeterminate;
+    }
+    else if (!is_char(input) || is_ctl(input) || is_tspecial(input))
+    {
+      return false;
+    }
+    else
+    {
+      req.headers.back().name.push_back(input);
+      return boost::indeterminate;
+    }
+  case space_before_header_value:
+    if (input == ' ')
+    {
+      state_ = header_value;
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case header_value:
+    if (input == '\r')
+    {
+      state_ = expecting_newline_2;
+      return boost::indeterminate;
+    }
+    else if (is_ctl(input))
+    {
+      return false;
+    }
+    else
+    {
+      req.headers.back().value.push_back(input);
+      return boost::indeterminate;
+    }
+  case expecting_newline_2:
+    if (input == '\n')
+    {
+      state_ = header_line_start;
+      return boost::indeterminate;
+    }
+    else
+    {
+      return false;
+    }
+  case expecting_newline_3:
+    return (input == '\n');
+  default:
+    return false;
+  }
+}
+
+bool request_parser::is_char(int c)
+{
+  return c >= 0 && c <= 127;
+}
+
+bool request_parser::is_ctl(int c)
+{
+  return (c >= 0 && c <= 31) || (c == 127);
+}
+
+bool request_parser::is_tspecial(int c)
+{
+  switch (c)
+  {
+  case '(': case ')': case '<': case '>': case '@':
+  case ',': case ';': case ':': case '\\': case '"':
+  case '/': case '[': case ']': case '?': case '=':
+  case '{': case '}': case ' ': case '\t':
+    return true;
+  default:
+    return false;
+  }
+}
+
+bool request_parser::is_digit(int c)
+{
+  return c >= '0' && c <= '9';
+}
+
+} // namespace server3
+} // namespace http

doc/html/boost_asio/example/cpp03/http/server3/request_parser.hpp

@@ -0,0 +1,95 @@
+//
+// request_parser.hpp
+// ~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef HTTP_SERVER3_REQUEST_PARSER_HPP
+#define HTTP_SERVER3_REQUEST_PARSER_HPP
+
+#include <boost/logic/tribool.hpp>
+#include <boost/tuple/tuple.hpp>
+
+namespace http {
+namespace server3 {
+
+struct request;
+
+/// Parser for incoming requests.
+class request_parser
+{
+public:
+  /// Construct ready to parse the request method.
+  request_parser();
+
+  /// Reset to initial parser state.
+  void reset();
+
+  /// Parse some data. The tribool return value is true when a complete request
+  /// has been parsed, false if the data is invalid, indeterminate when more
+  /// data is required. The InputIterator return value indicates how much of the
+  /// input has been consumed.
+  template <typename InputIterator>
+  boost::tuple<boost::tribool, InputIterator> parse(request& req,
+      InputIterator begin, InputIterator end)
+  {
+    while (begin != end)
+    {
+      boost::tribool result = consume(req, *begin++);
+      if (result || !result)
+        return boost::make_tuple(result, begin);
+    }
+    boost::tribool result = boost::indeterminate;
+    return boost::make_tuple(result, begin);
+  }
+
+private:
+  /// Handle the next character of input.
+  boost::tribool consume(request& req, char input);
+
+  /// Check if a byte is an HTTP character.
+  static bool is_char(int c);
+
+  /// Check if a byte is an HTTP control character.
+  static bool is_ctl(int c);
+
+  /// Check if a byte is defined as an HTTP tspecial character.
+  static bool is_tspecial(int c);
+
+  /// Check if a byte is a digit.
+  static bool is_digit(int c);
+
+  /// The current state of the parser.
+  enum state
+  {
+    method_start,
+    method,
+    uri,
+    http_version_h,
+    http_version_t_1,
+    http_version_t_2,
+    http_version_p,
+    http_version_slash,
+    http_version_major_start,
+    http_version_major,
+    http_version_minor_start,
+    http_version_minor,
+    expecting_newline_1,
+    header_line_start,
+    header_lws,
+    header_name,
+    space_before_header_value,
+    header_value,
+    expecting_newline_2,
+    expecting_newline_3
+  } state_;
+};
+
+} // namespace server3
+} // namespace http
+
+#endif // HTTP_SERVER3_REQUEST_PARSER_HPP

doc/html/boost_asio/example/cpp03/http/server3/server.cpp

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+//
+// server.cpp
+// ~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include "server.hpp"
+#include <boost/thread/thread.hpp>
+#include <boost/bind/bind.hpp>
+#include <boost/shared_ptr.hpp>
+#include <vector>
+
+namespace http {
+namespace server3 {
+
+server::server(const std::string& address, const std::string& port,
+    const std::string& doc_root, std::size_t thread_pool_size)
+  : thread_pool_size_(thread_pool_size),
+    signals_(io_context_),
+    acceptor_(io_context_),
+    new_connection_(),
+    request_handler_(doc_root)
+{
+  // Register to handle the signals that indicate when the server should exit.
+  // It is safe to register for the same signal multiple times in a program,
+  // provided all registration for the specified signal is made through Asio.
+  signals_.add(SIGINT);
+  signals_.add(SIGTERM);
+#if defined(SIGQUIT)
+  signals_.add(SIGQUIT);
+#endif // defined(SIGQUIT)
+  signals_.async_wait(boost::bind(&server::handle_stop, this));
+
+  // Open the acceptor with the option to reuse the address (i.e. SO_REUSEADDR).
+  boost::asio::ip::tcp::resolver resolver(io_context_);
+  boost::asio::ip::tcp::endpoint endpoint =
+    *resolver.resolve(address, port).begin();
+  acceptor_.open(endpoint.protocol());
+  acceptor_.set_option(boost::asio::ip::tcp::acceptor::reuse_address(true));
+  acceptor_.bind(endpoint);
+  acceptor_.listen();
+
+  start_accept();
+}
+
+void server::run()
+{
+  // Create a pool of threads to run all of the io_contexts.
+  std::vector<boost::shared_ptr<boost::thread> > threads;
+  for (std::size_t i = 0; i < thread_pool_size_; ++i)
+  {
+    boost::shared_ptr<boost::thread> thread(new boost::thread(
+          boost::bind(&boost::asio::io_context::run, &io_context_)));
+    threads.push_back(thread);
+  }
+
+  // Wait for all threads in the pool to exit.
+  for (std::size_t i = 0; i < threads.size(); ++i)
+    threads[i]->join();
+}
+
+void server::start_accept()
+{
+  new_connection_.reset(new connection(io_context_, request_handler_));
+  acceptor_.async_accept(new_connection_->socket(),
+      boost::bind(&server::handle_accept, this,
+        boost::asio::placeholders::error));
+}
+
+void server::handle_accept(const boost::system::error_code& e)
+{
+  if (!e)
+  {
+    new_connection_->start();
+  }
+
+  start_accept();
+}
+
+void server::handle_stop()
+{
+  io_context_.stop();
+}
+
+} // namespace server3
+} // namespace http

doc/html/boost_asio/example/cpp03/http/server3/server.hpp

@@ -0,0 +1,70 @@
+//
+// server.hpp
+// ~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef HTTP_SERVER3_SERVER_HPP
+#define HTTP_SERVER3_SERVER_HPP
+
+#include <boost/asio.hpp>
+#include <string>
+#include <vector>
+#include <boost/noncopyable.hpp>
+#include <boost/shared_ptr.hpp>
+#include "connection.hpp"
+#include "request_handler.hpp"
+
+namespace http {
+namespace server3 {
+
+/// The top-level class of the HTTP server.
+class server
+  : private boost::noncopyable
+{
+public:
+  /// Construct the server to listen on the specified TCP address and port, and
+  /// serve up files from the given directory.
+  explicit server(const std::string& address, const std::string& port,
+      const std::string& doc_root, std::size_t thread_pool_size);
+
+  /// Run the server's io_context loop.
+  void run();
+
+private:
+  /// Initiate an asynchronous accept operation.
+  void start_accept();
+
+  /// Handle completion of an asynchronous accept operation.
+  void handle_accept(const boost::system::error_code& e);
+
+  /// Handle a request to stop the server.
+  void handle_stop();
+
+  /// The number of threads that will call io_context::run().
+  std::size_t thread_pool_size_;
+
+  /// The io_context used to perform asynchronous operations.
+  boost::asio::io_context io_context_;
+
+  /// The signal_set is used to register for process termination notifications.
+  boost::asio::signal_set signals_;
+
+  /// Acceptor used to listen for incoming connections.
+  boost::asio::ip::tcp::acceptor acceptor_;
+
+  /// The next connection to be accepted.
+  connection_ptr new_connection_;
+
+  /// The handler for all incoming requests.
+  request_handler request_handler_;
+};
+
+} // namespace server3
+} // namespace http
+
+#endif // HTTP_SERVER3_SERVER_HPP

doc/html/boost_asio/example/cpp03/http/server4/file_handler.cpp

@@ -0,0 +1,122 @@
+//
+// file_handler.cpp
+// ~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include "file_handler.hpp"
+#include <fstream>
+#include <sstream>
+#include <string>
+#include <boost/lexical_cast.hpp>
+#include "mime_types.hpp"
+#include "reply.hpp"
+#include "request.hpp"
+
+namespace http {
+namespace server4 {
+
+file_handler::file_handler(const std::string& doc_root)
+  : doc_root_(doc_root)
+{
+}
+
+void file_handler::operator()(const request& req, reply& rep)
+{
+  // Decode url to path.
+  std::string request_path;
+  if (!url_decode(req.uri, request_path))
+  {
+    rep = reply::stock_reply(reply::bad_request);
+    return;
+  }
+
+  // Request path must be absolute and not contain "..".
+  if (request_path.empty() || request_path[0] != '/'
+      || request_path.find("..") != std::string::npos)
+  {
+    rep = reply::stock_reply(reply::bad_request);
+    return;
+  }
+
+  // If path ends in slash (i.e. is a directory) then add "index.html".
+  if (request_path[request_path.size() - 1] == '/')
+  {
+    request_path += "index.html";
+  }
+
+  // Determine the file extension.
+  std::size_t last_slash_pos = request_path.find_last_of("/");
+  std::size_t last_dot_pos = request_path.find_last_of(".");
+  std::string extension;
+  if (last_dot_pos != std::string::npos && last_dot_pos > last_slash_pos)
+  {
+    extension = request_path.substr(last_dot_pos + 1);
+  }
+
+  // Open the file to send back.
+  std::string full_path = doc_root_ + request_path;
+  std::ifstream is(full_path.c_str(), std::ios::in | std::ios::binary);
+  if (!is)
+  {
+    rep = reply::stock_reply(reply::not_found);
+    return;
+  }
+
+  // Fill out the reply to be sent to the client.
+  rep.status = reply::ok;
+  char buf[512];
+  while (is.read(buf, sizeof(buf)).gcount() > 0)
+    rep.content.append(buf, is.gcount());
+  rep.headers.resize(2);
+  rep.headers[0].name = "Content-Length";
+  rep.headers[0].value = boost::lexical_cast<std::string>(rep.content.size());
+  rep.headers[1].name = "Content-Type";
+  rep.headers[1].value = mime_types::extension_to_type(extension);
+}
+
+bool file_handler::url_decode(const std::string& in, std::string& out)
+{
+  out.clear();
+  out.reserve(in.size());
+  for (std::size_t i = 0; i < in.size(); ++i)
+  {
+    if (in[i] == '%')
+    {
+      if (i + 3 <= in.size())
+      {
+        int value = 0;
+        std::istringstream is(in.substr(i + 1, 2));
+        if (is >> std::hex >> value)
+        {
+          out += static_cast<char>(value);
+          i += 2;
+        }
+        else
+        {
+          return false;
+        }
+      }
+      else
+      {
+        return false;
+      }
+    }
+    else if (in[i] == '+')
+    {
+      out += ' ';
+    }
+    else
+    {
+      out += in[i];
+    }
+  }
+  return true;
+}
+
+} // namespace server4
+} // namespace http

doc/html/boost_asio/example/cpp03/http/server4/file_handler.hpp

@@ -0,0 +1,44 @@
+//
+// file_handler.hpp
+// ~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef HTTP_SERVER4_FILE_HANDLER_HPP
+#define HTTP_SERVER4_FILE_HANDLER_HPP
+
+#include <string>
+
+namespace http {
+namespace server4 {
+
+struct reply;
+struct request;
+
+/// The common handler for all incoming requests.
+class file_handler
+{
+public:
+  /// Construct with a directory containing files to be served.
+  explicit file_handler(const std::string& doc_root);
+
+  /// Handle a request and produce a reply.
+  void operator()(const request& req, reply& rep);
+
+private:
+  /// The directory containing the files to be served.
+  std::string doc_root_;
+
+  /// Perform URL-decoding on a string. Returns false if the encoding was
+  /// invalid.
+  static bool url_decode(const std::string& in, std::string& out);
+};
+
+} // namespace server4
+} // namespace http
+
+#endif // HTTP_SERVER4_FILE_HANDLER_HPP

doc/html/boost_asio/example/cpp03/http/server4/header.hpp

@@ -0,0 +1,28 @@
+//
+// header.hpp
+// ~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef HTTP_SERVER4_HEADER_HPP
+#define HTTP_SERVER4_HEADER_HPP
+
+#include <string>
+
+namespace http {
+namespace server4 {
+
+struct header
+{
+  std::string name;
+  std::string value;
+};
+
+} // namespace server4
+} // namespace http
+
+#endif // HTTP_SERVER4_HEADER_HPP

doc/html/boost_asio/example/cpp03/http/server4/main.cpp

@@ -0,0 +1,58 @@
+//
+// main.cpp
+// ~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <iostream>
+#include <boost/asio.hpp>
+#include <boost/bind/bind.hpp>
+#include <signal.h>
+#include "server.hpp"
+#include "file_handler.hpp"
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    // Check command line arguments.
+    if (argc != 4)
+    {
+      std::cerr << "Usage: http_server <address> <port> <doc_root>\n";
+      std::cerr << "  For IPv4, try:\n";
+      std::cerr << "    receiver 0.0.0.0 80 .\n";
+      std::cerr << "  For IPv6, try:\n";
+      std::cerr << "    receiver 0::0 80 .\n";
+      return 1;
+    }
+
+    boost::asio::io_context io_context;
+
+    // Launch the initial server coroutine.
+    http::server4::server(io_context, argv[1], argv[2],
+        http::server4::file_handler(argv[3]))();
+
+    // Wait for signals indicating time to shut down.
+    boost::asio::signal_set signals(io_context);
+    signals.add(SIGINT);
+    signals.add(SIGTERM);
+#if defined(SIGQUIT)
+    signals.add(SIGQUIT);
+#endif // defined(SIGQUIT)
+    signals.async_wait(boost::bind(
+          &boost::asio::io_context::stop, &io_context));
+
+    // Run the server.
+    io_context.run();
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << "exception: " << e.what() << "\n";
+  }
+
+  return 0;
+}

doc/html/boost_asio/example/cpp03/http/server4/mime_types.cpp

@@ -0,0 +1,46 @@
+//
+// mime_types.cpp
+// ~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include "mime_types.hpp"
+
+namespace http {
+namespace server4 {
+namespace mime_types {
+
+struct mapping
+{
+  const char* extension;
+  const char* mime_type;
+} mappings[] =
+{
+  { "gif", "image/gif" },
+  { "htm", "text/html" },
+  { "html", "text/html" },
+  { "jpg", "image/jpeg" },
+  { "png", "image/png" },
+  { 0, 0 } // Marks end of list.
+};
+
+std::string extension_to_type(const std::string& extension)
+{
+  for (mapping* m = mappings; m->extension; ++m)
+  {
+    if (m->extension == extension)
+    {
+      return m->mime_type;
+    }
+  }
+
+  return "text/plain";
+}
+
+} // namespace mime_types
+} // namespace server4
+} // namespace http

doc/html/boost_asio/example/cpp03/http/server4/mime_types.hpp

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+//
+// mime_types.hpp
+// ~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef HTTP_SERVER4_MIME_TYPES_HPP
+#define HTTP_SERVER4_MIME_TYPES_HPP
+
+#include <string>
+
+namespace http {
+namespace server4 {
+namespace mime_types {
+
+/// Convert a file extension into a MIME type.
+std::string extension_to_type(const std::string& extension);
+
+} // namespace mime_types
+} // namespace server4
+} // namespace http
+
+#endif // HTTP_SERVER4_MIME_TYPES_HPP

doc/html/boost_asio/example/cpp03/http/server4/reply.cpp

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+//
+// reply.cpp
+// ~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include "reply.hpp"
+#include <string>
+#include <boost/lexical_cast.hpp>
+
+namespace http {
+namespace server4 {
+
+namespace status_strings {
+
+const std::string ok =
+  "HTTP/1.0 200 OK\r\n";
+const std::string created =
+  "HTTP/1.0 201 Created\r\n";
+const std::string accepted =
+  "HTTP/1.0 202 Accepted\r\n";
+const std::string no_content =
+  "HTTP/1.0 204 No Content\r\n";
+const std::string multiple_choices =
+  "HTTP/1.0 300 Multiple Choices\r\n";
+const std::string moved_permanently =
+  "HTTP/1.0 301 Moved Permanently\r\n";
+const std::string moved_temporarily =
+  "HTTP/1.0 302 Moved Temporarily\r\n";
+const std::string not_modified =
+  "HTTP/1.0 304 Not Modified\r\n";
+const std::string bad_request =
+  "HTTP/1.0 400 Bad Request\r\n";
+const std::string unauthorized =
+  "HTTP/1.0 401 Unauthorized\r\n";
+const std::string forbidden =
+  "HTTP/1.0 403 Forbidden\r\n";
+const std::string not_found =
+  "HTTP/1.0 404 Not Found\r\n";
+const std::string internal_server_error =
+  "HTTP/1.0 500 Internal Server Error\r\n";
+const std::string not_implemented =
+  "HTTP/1.0 501 Not Implemented\r\n";
+const std::string bad_gateway =
+  "HTTP/1.0 502 Bad Gateway\r\n";
+const std::string service_unavailable =
+  "HTTP/1.0 503 Service Unavailable\r\n";
+
+boost::asio::const_buffer to_buffer(reply::status_type status)
+{
+  switch (status)
+  {
+  case reply::ok:
+    return boost::asio::buffer(ok);
+  case reply::created:
+    return boost::asio::buffer(created);
+  case reply::accepted:
+    return boost::asio::buffer(accepted);
+  case reply::no_content:
+    return boost::asio::buffer(no_content);
+  case reply::multiple_choices:
+    return boost::asio::buffer(multiple_choices);
+  case reply::moved_permanently:
+    return boost::asio::buffer(moved_permanently);
+  case reply::moved_temporarily:
+    return boost::asio::buffer(moved_temporarily);
+  case reply::not_modified:
+    return boost::asio::buffer(not_modified);
+  case reply::bad_request:
+    return boost::asio::buffer(bad_request);
+  case reply::unauthorized:
+    return boost::asio::buffer(unauthorized);
+  case reply::forbidden:
+    return boost::asio::buffer(forbidden);
+  case reply::not_found:
+    return boost::asio::buffer(not_found);
+  case reply::internal_server_error:
+    return boost::asio::buffer(internal_server_error);
+  case reply::not_implemented:
+    return boost::asio::buffer(not_implemented);
+  case reply::bad_gateway:
+    return boost::asio::buffer(bad_gateway);
+  case reply::service_unavailable:
+    return boost::asio::buffer(service_unavailable);
+  default:
+    return boost::asio::buffer(internal_server_error);
+  }
+}
+
+} // namespace status_strings
+
+namespace misc_strings {
+
+const char name_value_separator[] = { ':', ' ' };
+const char crlf[] = { '\r', '\n' };
+
+} // namespace misc_strings
+
+std::vector<boost::asio::const_buffer> reply::to_buffers()
+{
+  std::vector<boost::asio::const_buffer> buffers;
+  buffers.push_back(status_strings::to_buffer(status));
+  for (std::size_t i = 0; i < headers.size(); ++i)
+  {
+    header& h = headers[i];
+    buffers.push_back(boost::asio::buffer(h.name));
+    buffers.push_back(boost::asio::buffer(misc_strings::name_value_separator));
+    buffers.push_back(boost::asio::buffer(h.value));
+    buffers.push_back(boost::asio::buffer(misc_strings::crlf));
+  }
+  buffers.push_back(boost::asio::buffer(misc_strings::crlf));
+  buffers.push_back(boost::asio::buffer(content));
+  return buffers;
+}
+
+namespace stock_replies {
+
+const char ok[] = "";
+const char created[] =
+  "<html>"
+  "<head><title>Created</title></head>"
+  "<body><h1>201 Created</h1></body>"
+  "</html>";
+const char accepted[] =
+  "<html>"
+  "<head><title>Accepted</title></head>"
+  "<body><h1>202 Accepted</h1></body>"
+  "</html>";
+const char no_content[] =
+  "<html>"
+  "<head><title>No Content</title></head>"
+  "<body><h1>204 Content</h1></body>"
+  "</html>";
+const char multiple_choices[] =
+  "<html>"
+  "<head><title>Multiple Choices</title></head>"
+  "<body><h1>300 Multiple Choices</h1></body>"
+  "</html>";
+const char moved_permanently[] =
+  "<html>"
+  "<head><title>Moved Permanently</title></head>"
+  "<body><h1>301 Moved Permanently</h1></body>"
+  "</html>";
+const char moved_temporarily[] =
+  "<html>"
+  "<head><title>Moved Temporarily</title></head>"
+  "<body><h1>302 Moved Temporarily</h1></body>"
+  "</html>";
+const char not_modified[] =
+  "<html>"
+  "<head><title>Not Modified</title></head>"
+  "<body><h1>304 Not Modified</h1></body>"
+  "</html>";
+const char bad_request[] =
+  "<html>"
+  "<head><title>Bad Request</title></head>"
+  "<body><h1>400 Bad Request</h1></body>"
+  "</html>";
+const char unauthorized[] =
+  "<html>"
+  "<head><title>Unauthorized</title></head>"
+  "<body><h1>401 Unauthorized</h1></body>"
+  "</html>";
+const char forbidden[] =
+  "<html>"
+  "<head><title>Forbidden</title></head>"
+  "<body><h1>403 Forbidden</h1></body>"
+  "</html>";
+const char not_found[] =
+  "<html>"
+  "<head><title>Not Found</title></head>"
+  "<body><h1>404 Not Found</h1></body>"
+  "</html>";
+const char internal_server_error[] =
+  "<html>"
+  "<head><title>Internal Server Error</title></head>"
+  "<body><h1>500 Internal Server Error</h1></body>"
+  "</html>";
+const char not_implemented[] =
+  "<html>"
+  "<head><title>Not Implemented</title></head>"
+  "<body><h1>501 Not Implemented</h1></body>"
+  "</html>";
+const char bad_gateway[] =
+  "<html>"
+  "<head><title>Bad Gateway</title></head>"
+  "<body><h1>502 Bad Gateway</h1></body>"
+  "</html>";
+const char service_unavailable[] =
+  "<html>"
+  "<head><title>Service Unavailable</title></head>"
+  "<body><h1>503 Service Unavailable</h1></body>"
+  "</html>";
+
+std::string to_string(reply::status_type status)
+{
+  switch (status)
+  {
+  case reply::ok:
+    return ok;
+  case reply::created:
+    return created;
+  case reply::accepted:
+    return accepted;
+  case reply::no_content:
+    return no_content;
+  case reply::multiple_choices:
+    return multiple_choices;
+  case reply::moved_permanently:
+    return moved_permanently;
+  case reply::moved_temporarily:
+    return moved_temporarily;
+  case reply::not_modified:
+    return not_modified;
+  case reply::bad_request:
+    return bad_request;
+  case reply::unauthorized:
+    return unauthorized;
+  case reply::forbidden:
+    return forbidden;
+  case reply::not_found:
+    return not_found;
+  case reply::internal_server_error:
+    return internal_server_error;
+  case reply::not_implemented:
+    return not_implemented;
+  case reply::bad_gateway:
+    return bad_gateway;
+  case reply::service_unavailable:
+    return service_unavailable;
+  default:
+    return internal_server_error;
+  }
+}
+
+} // namespace stock_replies
+
+reply reply::stock_reply(reply::status_type status)
+{
+  reply rep;
+  rep.status = status;
+  rep.content = stock_replies::to_string(status);
+  rep.headers.resize(2);
+  rep.headers[0].name = "Content-Length";
+  rep.headers[0].value = boost::lexical_cast<std::string>(rep.content.size());
+  rep.headers[1].name = "Content-Type";
+  rep.headers[1].value = "text/html";
+  return rep;
+}
+
+} // namespace server4
+} // namespace http

doc/html/boost_asio/example/cpp03/http/server4/reply.hpp

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+//
+// reply.hpp
+// ~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef HTTP_SERVER4_REPLY_HPP
+#define HTTP_SERVER4_REPLY_HPP
+
+#include <string>
+#include <vector>
+#include <boost/asio.hpp>
+#include "header.hpp"
+
+namespace http {
+namespace server4 {
+
+/// A reply to be sent to a client.
+struct reply
+{
+  /// The status of the reply.
+  enum status_type
+  {
+    ok = 200,
+    created = 201,
+    accepted = 202,
+    no_content = 204,
+    multiple_choices = 300,
+    moved_permanently = 301,
+    moved_temporarily = 302,
+    not_modified = 304,
+    bad_request = 400,
+    unauthorized = 401,
+    forbidden = 403,
+    not_found = 404,
+    internal_server_error = 500,
+    not_implemented = 501,
+    bad_gateway = 502,
+    service_unavailable = 503
+  } status;
+
+  /// The headers to be included in the reply.
+  std::vector<header> headers;
+
+  /// The content to be sent in the reply.
+  std::string content;
+
+  /// Convert the reply into a vector of buffers. The buffers do not own the
+  /// underlying memory blocks, therefore the reply object must remain valid and
+  /// not be changed until the write operation has completed.
+  std::vector<boost::asio::const_buffer> to_buffers();
+
+  /// Get a stock reply.
+  static reply stock_reply(status_type status);
+};
+
+} // namespace server4
+} // namespace http
+
+#endif // HTTP_SERVER4_REPLY_HPP

doc/html/boost_asio/example/cpp03/http/server4/request.hpp

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+//
+// request.hpp
+// ~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef HTTP_SERVER4_REQUEST_HPP
+#define HTTP_SERVER4_REQUEST_HPP
+
+#include <string>
+#include <vector>
+#include "header.hpp"
+
+namespace http {
+namespace server4 {
+
+/// A request received from a client.
+struct request
+{
+  /// The request method, e.g. "GET", "POST".
+  std::string method;
+
+  /// The requested URI, such as a path to a file.
+  std::string uri;
+
+  /// Major version number, usually 1.
+  int http_version_major;
+
+  /// Minor version number, usually 0 or 1.
+  int http_version_minor;
+
+  /// The headers included with the request.
+  std::vector<header> headers;
+
+  /// The optional content sent with the request.
+  std::string content;
+};
+
+} // namespace server4
+} // namespace http
+
+#endif // HTTP_SERVER4_REQUEST_HPP

doc/html/boost_asio/example/cpp03/http/server4/request_parser.cpp

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+//
+// request_parser.cpp
+// ~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include "request_parser.hpp"
+#include <algorithm>
+#include <cctype>
+#include <boost/lexical_cast.hpp>
+#include "request.hpp"
+
+namespace http {
+namespace server4 {
+
+// Enable the pseudo-keywords reenter, yield and fork.
+#include <boost/asio/yield.hpp>
+
+std::string request_parser::content_length_name_ = "Content-Length";
+
+boost::tribool request_parser::consume(request& req, char c)
+{
+  reenter (this)
+  {
+    req.method.clear();
+    req.uri.clear();
+    req.http_version_major = 0;
+    req.http_version_minor = 0;
+    req.headers.clear();
+    req.content.clear();
+    content_length_ = 0;
+
+    // Request method.
+    while (is_char(c) && !is_ctl(c) && !is_tspecial(c) && c != ' ')
+    {
+      req.method.push_back(c);
+      yield return boost::indeterminate;
+    }
+    if (req.method.empty())
+      return false;
+
+    // Space.
+    if (c != ' ') return false;
+    yield return boost::indeterminate;
+
+    // URI.
+    while (!is_ctl(c) && c != ' ')
+    {
+      req.uri.push_back(c);
+      yield return boost::indeterminate;
+    }
+    if (req.uri.empty()) return false;
+
+    // Space.
+    if (c != ' ') return false;
+    yield return boost::indeterminate;
+
+    // HTTP protocol identifier.
+    if (c != 'H') return false;
+    yield return boost::indeterminate;
+    if (c != 'T') return false;
+    yield return boost::indeterminate;
+    if (c != 'T') return false;
+    yield return boost::indeterminate;
+    if (c != 'P') return false;
+    yield return boost::indeterminate;
+
+    // Slash.
+    if (c != '/') return false;
+    yield return boost::indeterminate;
+
+    // Major version number.
+    if (!is_digit(c)) return false;
+    while (is_digit(c))
+    {
+      req.http_version_major = req.http_version_major * 10 + c - '0';
+      yield return boost::indeterminate;
+    }
+
+    // Dot.
+    if (c != '.') return false;
+    yield return boost::indeterminate;
+
+    // Minor version number.
+    if (!is_digit(c)) return false;
+    while (is_digit(c))
+    {
+      req.http_version_minor = req.http_version_minor * 10 + c - '0';
+      yield return boost::indeterminate;
+    }
+
+    // CRLF.
+    if (c != '\r') return false;
+    yield return boost::indeterminate;
+    if (c != '\n') return false;
+    yield return boost::indeterminate;
+
+    // Headers.
+    while ((is_char(c) && !is_ctl(c) && !is_tspecial(c) && c != '\r')
+        || (c == ' ' || c == '\t'))
+    {
+      if (c == ' ' || c == '\t')
+      {
+        // Leading whitespace. Must be continuation of previous header's value.
+        if (req.headers.empty()) return false;
+        while (c == ' ' || c == '\t')
+          yield return boost::indeterminate;
+      }
+      else
+      {
+        // Start the next header.
+        req.headers.push_back(header());
+
+        // Header name.
+        while (is_char(c) && !is_ctl(c) && !is_tspecial(c) && c != ':')
+        {
+          req.headers.back().name.push_back(c);
+          yield return boost::indeterminate;
+        }
+
+        // Colon and space separates the header name from the header value.
+        if (c != ':') return false;
+        yield return boost::indeterminate;
+        if (c != ' ') return false;
+        yield return boost::indeterminate;
+      }
+
+      // Header value.
+      while (is_char(c) && !is_ctl(c) && c != '\r')
+      {
+        req.headers.back().value.push_back(c);
+        yield return boost::indeterminate;
+      }
+
+      // CRLF.
+      if (c != '\r') return false;
+      yield return boost::indeterminate;
+      if (c != '\n') return false;
+      yield return boost::indeterminate;
+    }
+
+    // CRLF.
+    if (c != '\r') return false;
+    yield return boost::indeterminate;
+    if (c != '\n') return false;
+
+    // Check for optional Content-Length header.
+    for (std::size_t i = 0; i < req.headers.size(); ++i)
+    {
+      if (headers_equal(req.headers[i].name, content_length_name_))
+      {
+        try
+        {
+          content_length_ =
+            boost::lexical_cast<std::size_t>(req.headers[i].value);
+        }
+        catch (boost::bad_lexical_cast&)
+        {
+          return false;
+        }
+      }
+    }
+
+    // Content.
+    while (req.content.size() < content_length_)
+    {
+      yield return boost::indeterminate;
+      req.content.push_back(c);
+    }
+  }
+
+  return true;
+}
+
+// Disable the pseudo-keywords reenter, yield and fork.
+#include <boost/asio/unyield.hpp>
+
+bool request_parser::is_char(int c)
+{
+  return c >= 0 && c <= 127;
+}
+
+bool request_parser::is_ctl(int c)
+{
+  return (c >= 0 && c <= 31) || (c == 127);
+}
+
+bool request_parser::is_tspecial(int c)
+{
+  switch (c)
+  {
+  case '(': case ')': case '<': case '>': case '@':
+  case ',': case ';': case ':': case '\\': case '"':
+  case '/': case '[': case ']': case '?': case '=':
+  case '{': case '}': case ' ': case '\t':
+    return true;
+  default:
+    return false;
+  }
+}
+
+bool request_parser::is_digit(int c)
+{
+  return c >= '0' && c <= '9';
+}
+
+bool request_parser::tolower_compare(char a, char b)
+{
+  return std::tolower(a) == std::tolower(b);
+}
+
+bool request_parser::headers_equal(const std::string& a, const std::string& b)
+{
+  if (a.length() != b.length())
+    return false;
+
+  return std::equal(a.begin(), a.end(), b.begin(),
+      &request_parser::tolower_compare);
+}
+
+} // namespace server4
+} // namespace http

doc/html/boost_asio/example/cpp03/http/server4/request_parser.hpp

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+//
+// request_parser.hpp
+// ~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef HTTP_SERVER4_REQUEST_PARSER_HPP
+#define HTTP_SERVER4_REQUEST_PARSER_HPP
+
+#include <string>
+#include <boost/logic/tribool.hpp>
+#include <boost/tuple/tuple.hpp>
+#include <boost/asio/coroutine.hpp>
+
+namespace http {
+namespace server4 {
+
+struct request;
+
+/// Parser for incoming requests.
+class request_parser : boost::asio::coroutine
+{
+public:
+  /// Parse some data. The tribool return value is true when a complete request
+  /// has been parsed, false if the data is invalid, indeterminate when more
+  /// data is required. The InputIterator return value indicates how much of the
+  /// input has been consumed.
+  template <typename InputIterator>
+  boost::tuple<boost::tribool, InputIterator> parse(request& req,
+      InputIterator begin, InputIterator end)
+  {
+    while (begin != end)
+    {
+      boost::tribool result = consume(req, *begin++);
+      if (result || !result)
+        return boost::make_tuple(result, begin);
+    }
+    boost::tribool result = boost::indeterminate;
+    return boost::make_tuple(result, begin);
+  }
+
+private:
+  /// The name of the content length header.
+  static std::string content_length_name_;
+
+  /// Content length as decoded from headers. Defaults to 0.
+  std::size_t content_length_;
+
+  /// Handle the next character of input.
+  boost::tribool consume(request& req, char input);
+
+  /// Check if a byte is an HTTP character.
+  static bool is_char(int c);
+
+  /// Check if a byte is an HTTP control character.
+  static bool is_ctl(int c);
+
+  /// Check if a byte is defined as an HTTP tspecial character.
+  static bool is_tspecial(int c);
+
+  /// Check if a byte is a digit.
+  static bool is_digit(int c);
+
+  /// Check if two characters are equal, without regard to case.
+  static bool tolower_compare(char a, char b);
+
+  /// Check whether the two request header names match.
+  bool headers_equal(const std::string& a, const std::string& b);
+};
+
+} // namespace server4
+} // namespace http
+
+#endif // HTTP_SERVER4_REQUEST_PARSER_HPP

doc/html/boost_asio/example/cpp03/http/server4/server.cpp

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+//
+// server.cpp
+// ~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include "server.hpp"
+#include "request.hpp"
+#include "reply.hpp"
+
+namespace http {
+namespace server4 {
+
+server::server(boost::asio::io_context& io_context,
+    const std::string& address, const std::string& port,
+    boost::function<void(const request&, reply&)> request_handler)
+  : request_handler_(request_handler)
+{
+  tcp::resolver resolver(io_context);
+  boost::asio::ip::tcp::endpoint endpoint =
+    *resolver.resolve(address, port).begin();
+  acceptor_.reset(new tcp::acceptor(io_context, endpoint));
+}
+
+// Enable the pseudo-keywords reenter, yield and fork.
+#include <boost/asio/yield.hpp>
+
+void server::operator()(boost::system::error_code ec, std::size_t length)
+{
+  // In this example we keep the error handling code in one place by
+  // hoisting it outside the coroutine. An alternative approach would be to
+  // check the value of ec after each yield for an asynchronous operation.
+  if (!ec)
+  {
+    // On reentering a coroutine, control jumps to the location of the last
+    // yield or fork. The argument to the "reenter" pseudo-keyword can be a
+    // pointer or reference to an object of type coroutine.
+    reenter (this)
+    {
+      // Loop to accept incoming connections.
+      do
+      {
+        // Create a new socket for the next incoming connection.
+        socket_.reset(new tcp::socket(acceptor_->get_executor()));
+
+        // Accept a new connection. The "yield" pseudo-keyword saves the current
+        // line number and exits the coroutine's "reenter" block. We use the
+        // server coroutine as the completion handler for the async_accept
+        // operation. When the asynchronous operation completes, the io_context
+        // invokes the function call operator, we "reenter" the coroutine, and
+        // then control resumes at the following line.
+        yield acceptor_->async_accept(*socket_, *this);
+
+        // We "fork" by cloning a new server coroutine to handle the connection.
+        // After forking we have a parent coroutine and a child coroutine. Both
+        // parent and child continue execution at the following line. They can
+        // be distinguished using the functions coroutine::is_parent() and
+        // coroutine::is_child().
+        fork server(*this)();
+
+        // The parent continues looping to accept the next incoming connection.
+        // The child exits the loop and processes the connection.
+      } while (is_parent());
+
+      // Create the objects needed to receive a request on the connection.
+      buffer_.reset(new boost::array<char, 8192>);
+      request_.reset(new request);
+
+      // Loop until a complete request (or an invalid one) has been received.
+      do
+      {
+        // Receive some more data. When control resumes at the following line,
+        // the ec and length parameters reflect the result of the asynchronous
+        // operation.
+        yield socket_->async_read_some(boost::asio::buffer(*buffer_), *this);
+
+        // Parse the data we just received.
+        boost::tie(valid_request_, boost::tuples::ignore)
+          = request_parser_.parse(*request_,
+              buffer_->data(), buffer_->data() + length);
+
+        // An indeterminate result means we need more data, so keep looping.
+      } while (boost::indeterminate(valid_request_));
+
+      // Create the reply object that will be sent back to the client.
+      reply_.reset(new reply);
+
+      if (valid_request_)
+      {
+        // A valid request was received. Call the user-supplied function object
+        // to process the request and compose a reply.
+        request_handler_(*request_, *reply_);
+      }
+      else
+      {
+        // The request was invalid.
+        *reply_ = reply::stock_reply(reply::bad_request);
+      }
+
+      // Send the reply back to the client.
+      yield boost::asio::async_write(*socket_, reply_->to_buffers(), *this);
+
+      // Initiate graceful connection closure.
+      socket_->shutdown(tcp::socket::shutdown_both, ec);
+    }
+  }
+
+  // If an error occurs then the coroutine is not reentered. Consequently, no
+  // new asynchronous operations are started. This means that all shared_ptr
+  // references will disappear and the resources associated with the coroutine
+  // will be destroyed automatically after this function call returns.
+}
+
+// Disable the pseudo-keywords reenter, yield and fork.
+#include <boost/asio/unyield.hpp>
+
+} // namespace server4
+} // namespace http

doc/html/boost_asio/example/cpp03/http/server4/server.hpp

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+//
+// server.hpp
+// ~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef HTTP_SERVER4_SERVER_HPP
+#define HTTP_SERVER4_SERVER_HPP
+
+#include <boost/asio.hpp>
+#include <string>
+#include <boost/array.hpp>
+#include <boost/function.hpp>
+#include <boost/shared_ptr.hpp>
+#include "request_parser.hpp"
+
+namespace http {
+namespace server4 {
+
+struct request;
+struct reply;
+
+/// The top-level coroutine of the HTTP server.
+class server : boost::asio::coroutine
+{
+public:
+  /// Construct the server to listen on the specified TCP address and port, and
+  /// serve up files from the given directory.
+  explicit server(boost::asio::io_context& io_context,
+      const std::string& address, const std::string& port,
+      boost::function<void(const request&, reply&)> request_handler);
+
+  /// Perform work associated with the server.
+  void operator()(
+      boost::system::error_code ec = boost::system::error_code(),
+      std::size_t length = 0);
+
+private:
+  typedef boost::asio::ip::tcp tcp;
+
+  /// The user-supplied handler for all incoming requests.
+  boost::function<void(const request&, reply&)> request_handler_;
+
+  /// Acceptor used to listen for incoming connections.
+  boost::shared_ptr<tcp::acceptor> acceptor_;
+
+  /// The current connection from a client.
+  boost::shared_ptr<tcp::socket> socket_;
+
+  /// Buffer for incoming data.
+  boost::shared_ptr<boost::array<char, 8192> > buffer_;
+
+  /// The incoming request.
+  boost::shared_ptr<request> request_;
+
+  /// Whether the request is valid or not.
+  boost::tribool valid_request_;
+
+  /// The parser for the incoming request.
+  request_parser request_parser_;
+
+  /// The reply to be sent back to the client.
+  boost::shared_ptr<reply> reply_;
+};
+
+} // namespace server4
+} // namespace http
+
+#endif // HTTP_SERVER4_SERVER_HPP

doc/html/boost_asio/example/cpp03/icmp/icmp_header.hpp

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+//
+// icmp_header.hpp
+// ~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef ICMP_HEADER_HPP
+#define ICMP_HEADER_HPP
+
+#include <istream>
+#include <ostream>
+#include <algorithm>
+
+// ICMP header for both IPv4 and IPv6.
+//
+// The wire format of an ICMP header is:
+// 
+// 0               8               16                             31
+// +---------------+---------------+------------------------------+      ---
+// |               |               |                              |       ^
+// |     type      |     code      |          checksum            |       |
+// |               |               |                              |       |
+// +---------------+---------------+------------------------------+    8 bytes
+// |                               |                              |       |
+// |          identifier           |       sequence number        |       |
+// |                               |                              |       v
+// +-------------------------------+------------------------------+      ---
+
+class icmp_header
+{
+public:
+  enum { echo_reply = 0, destination_unreachable = 3, source_quench = 4,
+    redirect = 5, echo_request = 8, time_exceeded = 11, parameter_problem = 12,
+    timestamp_request = 13, timestamp_reply = 14, info_request = 15,
+    info_reply = 16, address_request = 17, address_reply = 18 };
+
+  icmp_header() { std::fill(rep_, rep_ + sizeof(rep_), 0); }
+
+  unsigned char type() const { return rep_[0]; }
+  unsigned char code() const { return rep_[1]; }
+  unsigned short checksum() const { return decode(2, 3); }
+  unsigned short identifier() const { return decode(4, 5); }
+  unsigned short sequence_number() const { return decode(6, 7); }
+
+  void type(unsigned char n) { rep_[0] = n; }
+  void code(unsigned char n) { rep_[1] = n; }
+  void checksum(unsigned short n) { encode(2, 3, n); }
+  void identifier(unsigned short n) { encode(4, 5, n); }
+  void sequence_number(unsigned short n) { encode(6, 7, n); }
+
+  friend std::istream& operator>>(std::istream& is, icmp_header& header)
+    { return is.read(reinterpret_cast<char*>(header.rep_), 8); }
+
+  friend std::ostream& operator<<(std::ostream& os, const icmp_header& header)
+    { return os.write(reinterpret_cast<const char*>(header.rep_), 8); }
+
+private:
+  unsigned short decode(int a, int b) const
+    { return (rep_[a] << 8) + rep_[b]; }
+
+  void encode(int a, int b, unsigned short n)
+  {
+    rep_[a] = static_cast<unsigned char>(n >> 8);
+    rep_[b] = static_cast<unsigned char>(n & 0xFF);
+  }
+
+  unsigned char rep_[8];
+};
+
+template <typename Iterator>
+void compute_checksum(icmp_header& header,
+    Iterator body_begin, Iterator body_end)
+{
+  unsigned int sum = (header.type() << 8) + header.code()
+    + header.identifier() + header.sequence_number();
+
+  Iterator body_iter = body_begin;
+  while (body_iter != body_end)
+  {
+    sum += (static_cast<unsigned char>(*body_iter++) << 8);
+    if (body_iter != body_end)
+      sum += static_cast<unsigned char>(*body_iter++);
+  }
+
+  sum = (sum >> 16) + (sum & 0xFFFF);
+  sum += (sum >> 16);
+  header.checksum(static_cast<unsigned short>(~sum));
+}
+
+#endif // ICMP_HEADER_HPP

doc/html/boost_asio/example/cpp03/icmp/ipv4_header.hpp

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+//
+// ipv4_header.hpp
+// ~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef IPV4_HEADER_HPP
+#define IPV4_HEADER_HPP
+
+#include <algorithm>
+#include <boost/asio/ip/address_v4.hpp>
+
+// Packet header for IPv4.
+//
+// The wire format of an IPv4 header is:
+// 
+// 0               8               16                             31
+// +-------+-------+---------------+------------------------------+      ---
+// |       |       |               |                              |       ^
+// |version|header |    type of    |    total length in bytes     |       |
+// |  (4)  | length|    service    |                              |       |
+// +-------+-------+---------------+-+-+-+------------------------+       |
+// |                               | | | |                        |       |
+// |        identification         |0|D|M|    fragment offset     |       |
+// |                               | |F|F|                        |       |
+// +---------------+---------------+-+-+-+------------------------+       |
+// |               |               |                              |       |
+// | time to live  |   protocol    |       header checksum        |   20 bytes
+// |               |               |                              |       |
+// +---------------+---------------+------------------------------+       |
+// |                                                              |       |
+// |                      source IPv4 address                     |       |
+// |                                                              |       |
+// +--------------------------------------------------------------+       |
+// |                                                              |       |
+// |                   destination IPv4 address                   |       |
+// |                                                              |       v
+// +--------------------------------------------------------------+      ---
+// |                                                              |       ^
+// |                                                              |       |
+// /                        options (if any)                      /    0 - 40
+// /                                                              /     bytes
+// |                                                              |       |
+// |                                                              |       v
+// +--------------------------------------------------------------+      ---
+
+class ipv4_header
+{
+public:
+  ipv4_header() { std::fill(rep_, rep_ + sizeof(rep_), 0); }
+
+  unsigned char version() const { return (rep_[0] >> 4) & 0xF; }
+  unsigned short header_length() const { return (rep_[0] & 0xF) * 4; }
+  unsigned char type_of_service() const { return rep_[1]; }
+  unsigned short total_length() const { return decode(2, 3); }
+  unsigned short identification() const { return decode(4, 5); }
+  bool dont_fragment() const { return (rep_[6] & 0x40) != 0; }
+  bool more_fragments() const { return (rep_[6] & 0x20) != 0; }
+  unsigned short fragment_offset() const { return decode(6, 7) & 0x1FFF; }
+  unsigned int time_to_live() const { return rep_[8]; }
+  unsigned char protocol() const { return rep_[9]; }
+  unsigned short header_checksum() const { return decode(10, 11); }
+
+  boost::asio::ip::address_v4 source_address() const
+  {
+    boost::asio::ip::address_v4::bytes_type bytes
+      = { { rep_[12], rep_[13], rep_[14], rep_[15] } };
+    return boost::asio::ip::address_v4(bytes);
+  }
+
+  boost::asio::ip::address_v4 destination_address() const
+  {
+    boost::asio::ip::address_v4::bytes_type bytes
+      = { { rep_[16], rep_[17], rep_[18], rep_[19] } };
+    return boost::asio::ip::address_v4(bytes);
+  }
+
+  friend std::istream& operator>>(std::istream& is, ipv4_header& header)
+  {
+    is.read(reinterpret_cast<char*>(header.rep_), 20);
+    if (header.version() != 4)
+      is.setstate(std::ios::failbit);
+    std::streamsize options_length = header.header_length() - 20;
+    if (options_length < 0 || options_length > 40)
+      is.setstate(std::ios::failbit);
+    else
+      is.read(reinterpret_cast<char*>(header.rep_) + 20, options_length);
+    return is;
+  }
+
+private:
+  unsigned short decode(int a, int b) const
+    { return (rep_[a] << 8) + rep_[b]; }
+
+  unsigned char rep_[60];
+};
+
+#endif // IPV4_HEADER_HPP

doc/html/boost_asio/example/cpp03/icmp/ping.cpp

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+//
+// ping.cpp
+// ~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <boost/asio.hpp>
+#include <boost/bind/bind.hpp>
+#include <istream>
+#include <iostream>
+#include <ostream>
+
+#include "icmp_header.hpp"
+#include "ipv4_header.hpp"
+
+using boost::asio::ip::icmp;
+using boost::asio::steady_timer;
+namespace chrono = boost::asio::chrono;
+
+class pinger
+{
+public:
+  pinger(boost::asio::io_context& io_context, const char* destination)
+    : resolver_(io_context), socket_(io_context, icmp::v4()),
+      timer_(io_context), sequence_number_(0), num_replies_(0)
+  {
+    destination_ = *resolver_.resolve(icmp::v4(), destination, "").begin();
+
+    start_send();
+    start_receive();
+  }
+
+private:
+  void start_send()
+  {
+    std::string body("\"Hello!\" from Asio ping.");
+
+    // Create an ICMP header for an echo request.
+    icmp_header echo_request;
+    echo_request.type(icmp_header::echo_request);
+    echo_request.code(0);
+    echo_request.identifier(get_identifier());
+    echo_request.sequence_number(++sequence_number_);
+    compute_checksum(echo_request, body.begin(), body.end());
+
+    // Encode the request packet.
+    boost::asio::streambuf request_buffer;
+    std::ostream os(&request_buffer);
+    os << echo_request << body;
+
+    // Send the request.
+    time_sent_ = steady_timer::clock_type::now();
+    socket_.send_to(request_buffer.data(), destination_);
+
+    // Wait up to five seconds for a reply.
+    num_replies_ = 0;
+    timer_.expires_at(time_sent_ + chrono::seconds(5));
+    timer_.async_wait(boost::bind(&pinger::handle_timeout, this));
+  }
+
+  void handle_timeout()
+  {
+    if (num_replies_ == 0)
+      std::cout << "Request timed out" << std::endl;
+
+    // Requests must be sent no less than one second apart.
+    timer_.expires_at(time_sent_ + chrono::seconds(1));
+    timer_.async_wait(boost::bind(&pinger::start_send, this));
+  }
+
+  void start_receive()
+  {
+    // Discard any data already in the buffer.
+    reply_buffer_.consume(reply_buffer_.size());
+
+    // Wait for a reply. We prepare the buffer to receive up to 64KB.
+    socket_.async_receive(reply_buffer_.prepare(65536),
+        boost::bind(&pinger::handle_receive, this, boost::placeholders::_2));
+  }
+
+  void handle_receive(std::size_t length)
+  {
+    // The actual number of bytes received is committed to the buffer so that we
+    // can extract it using a std::istream object.
+    reply_buffer_.commit(length);
+
+    // Decode the reply packet.
+    std::istream is(&reply_buffer_);
+    ipv4_header ipv4_hdr;
+    icmp_header icmp_hdr;
+    is >> ipv4_hdr >> icmp_hdr;
+
+    // We can receive all ICMP packets received by the host, so we need to
+    // filter out only the echo replies that match the our identifier and
+    // expected sequence number.
+    if (is && icmp_hdr.type() == icmp_header::echo_reply
+          && icmp_hdr.identifier() == get_identifier()
+          && icmp_hdr.sequence_number() == sequence_number_)
+    {
+      // If this is the first reply, interrupt the five second timeout.
+      if (num_replies_++ == 0)
+        timer_.cancel();
+
+      // Print out some information about the reply packet.
+      chrono::steady_clock::time_point now = chrono::steady_clock::now();
+      chrono::steady_clock::duration elapsed = now - time_sent_;
+      std::cout << length - ipv4_hdr.header_length()
+        << " bytes from " << ipv4_hdr.source_address()
+        << ": icmp_seq=" << icmp_hdr.sequence_number()
+        << ", ttl=" << ipv4_hdr.time_to_live()
+        << ", time="
+        << chrono::duration_cast<chrono::milliseconds>(elapsed).count()
+        << std::endl;
+    }
+
+    start_receive();
+  }
+
+  static unsigned short get_identifier()
+  {
+#if defined(BOOST_ASIO_WINDOWS)
+    return static_cast<unsigned short>(::GetCurrentProcessId());
+#else
+    return static_cast<unsigned short>(::getpid());
+#endif
+  }
+
+  icmp::resolver resolver_;
+  icmp::endpoint destination_;
+  icmp::socket socket_;
+  steady_timer timer_;
+  unsigned short sequence_number_;
+  chrono::steady_clock::time_point time_sent_;
+  boost::asio::streambuf reply_buffer_;
+  std::size_t num_replies_;
+};
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    if (argc != 2)
+    {
+      std::cerr << "Usage: ping <host>" << std::endl;
+#if !defined(BOOST_ASIO_WINDOWS)
+      std::cerr << "(You may need to run this program as root.)" << std::endl;
+#endif
+      return 1;
+    }
+
+    boost::asio::io_context io_context;
+    pinger p(io_context, argv[1]);
+    io_context.run();
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << "Exception: " << e.what() << std::endl;
+  }
+}

doc/html/boost_asio/example/cpp03/invocation/prioritised_handlers.cpp

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+//
+// prioritised_handlers.cpp
+// ~~~~~~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <boost/asio.hpp>
+#include <boost/function.hpp>
+#include <iostream>
+#include <queue>
+
+using boost::asio::ip::tcp;
+
+class handler_priority_queue : public boost::asio::execution_context
+{
+public:
+  void add(int priority, boost::function<void()> function)
+  {
+    handlers_.push(queued_handler(priority, function));
+  }
+
+  void execute_all()
+  {
+    while (!handlers_.empty())
+    {
+      queued_handler handler = handlers_.top();
+      handler.execute();
+      handlers_.pop();
+    }
+  }
+
+  class executor
+  {
+  public:
+    executor(handler_priority_queue& q, int p)
+      : context_(q), priority_(p)
+    {
+    }
+
+    handler_priority_queue& context() const
+    {
+      return context_;
+    }
+
+    template <typename Function, typename Allocator>
+    void dispatch(const Function& f, const Allocator&) const
+    {
+      context_.add(priority_, f);
+    }
+
+    template <typename Function, typename Allocator>
+    void post(const Function& f, const Allocator&) const
+    {
+      context_.add(priority_, f);
+    }
+
+    template <typename Function, typename Allocator>
+    void defer(const Function& f, const Allocator&) const
+    {
+      context_.add(priority_, f);
+    }
+
+    void on_work_started() const {}
+    void on_work_finished() const {}
+
+    bool operator==(const executor& other) const
+    {
+      return &context_ == &other.context_ && priority_ == other.priority_;
+    }
+
+    bool operator!=(const executor& other) const
+    {
+      return !operator==(other);
+    }
+
+  private:
+    handler_priority_queue& context_;
+    int priority_;
+  };
+
+  template <typename Handler>
+  boost::asio::executor_binder<Handler, executor>
+  wrap(int priority, Handler handler)
+  {
+    return boost::asio::bind_executor(executor(*this, priority), handler);
+  }
+
+private:
+  class queued_handler
+  {
+  public:
+    queued_handler(int p, boost::function<void()> f)
+      : priority_(p), function_(f)
+    {
+    }
+
+    void execute()
+    {
+      function_();
+    }
+
+    friend bool operator<(const queued_handler& a,
+        const queued_handler& b)
+    {
+      return a.priority_ < b.priority_;
+    }
+
+  private:
+    int priority_;
+    boost::function<void()> function_;
+  };
+
+  std::priority_queue<queued_handler> handlers_;
+};
+
+//----------------------------------------------------------------------
+
+void high_priority_handler(const boost::system::error_code& /*ec*/)
+{
+  std::cout << "High priority handler\n";
+}
+
+void middle_priority_handler(const boost::system::error_code& /*ec*/)
+{
+  std::cout << "Middle priority handler\n";
+}
+
+void low_priority_handler()
+{
+  std::cout << "Low priority handler\n";
+}
+
+int main()
+{
+  boost::asio::io_context io_context;
+
+  handler_priority_queue pri_queue;
+
+  // Post a completion handler to be run immediately.
+  boost::asio::post(io_context, pri_queue.wrap(0, low_priority_handler));
+
+  // Start an asynchronous accept that will complete immediately.
+  tcp::endpoint endpoint(boost::asio::ip::address_v4::loopback(), 0);
+  tcp::acceptor acceptor(io_context, endpoint);
+  tcp::socket server_socket(io_context);
+  acceptor.async_accept(server_socket,
+      pri_queue.wrap(100, high_priority_handler));
+  tcp::socket client_socket(io_context);
+  client_socket.connect(acceptor.local_endpoint());
+
+  // Set a deadline timer to expire immediately.
+  boost::asio::steady_timer timer(io_context);
+  timer.expires_at(boost::asio::steady_timer::time_point::min());
+  timer.async_wait(pri_queue.wrap(42, middle_priority_handler));
+
+  while (io_context.run_one())
+  {
+    // The custom invocation hook adds the handlers to the priority queue
+    // rather than executing them from within the poll_one() call.
+    while (io_context.poll_one())
+      ;
+
+    pri_queue.execute_all();
+  }
+
+  return 0;
+}

doc/html/boost_asio/example/cpp03/iostreams/daytime_client.cpp

@@ -0,0 +1,44 @@
+//
+// daytime_client.cpp
+// ~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <iostream>
+#include <string>
+#include <boost/asio.hpp>
+
+using boost::asio::ip::tcp;
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    if (argc != 2)
+    {
+      std::cerr << "Usage: daytime_client <host>" << std::endl;
+      return 1;
+    }
+
+    tcp::iostream s(argv[1], "daytime");
+    if (!s)
+    {
+      std::cout << "Unable to connect: " << s.error().message() << std::endl;
+      return 1;
+    }
+
+    std::string line;
+    std::getline(s, line);
+    std::cout << line << std::endl;
+  }
+  catch (std::exception& e)
+  {
+    std::cout << "Exception: " << e.what() << std::endl;
+  }
+
+  return 0;
+}

doc/html/boost_asio/example/cpp03/iostreams/daytime_server.cpp

@@ -0,0 +1,51 @@
+//
+// daytime_server.cpp
+// ~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <ctime>
+#include <iostream>
+#include <string>
+#include <boost/asio.hpp>
+
+using boost::asio::ip::tcp;
+
+std::string make_daytime_string()
+{
+  using namespace std; // For time_t, time and ctime;
+  time_t now = time(0);
+  return ctime(&now);
+}
+
+int main()
+{
+  try
+  {
+    boost::asio::io_context io_context;
+
+    tcp::endpoint endpoint(tcp::v4(), 13);
+    tcp::acceptor acceptor(io_context, endpoint);
+
+    for (;;)
+    {
+      tcp::iostream stream;
+      boost::system::error_code ec;
+      acceptor.accept(stream.socket(), ec);
+      if (!ec)
+      {
+        stream << make_daytime_string();
+      }
+    }
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << e.what() << std::endl;
+  }
+
+  return 0;
+}

doc/html/boost_asio/example/cpp03/iostreams/http_client.cpp

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+//
+// http_client.cpp
+// ~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <iostream>
+#include <istream>
+#include <ostream>
+#include <string>
+#include <boost/asio/ip/tcp.hpp>
+
+using boost::asio::ip::tcp;
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    if (argc != 3)
+    {
+      std::cout << "Usage: http_client <server> <path>\n";
+      std::cout << "Example:\n";
+      std::cout << "  http_client www.boost.org /LICENSE_1_0.txt\n";
+      return 1;
+    }
+
+    boost::asio::ip::tcp::iostream s;
+
+    // The entire sequence of I/O operations must complete within 60 seconds.
+    // If an expiry occurs, the socket is automatically closed and the stream
+    // becomes bad.
+    s.expires_after(boost::asio::chrono::seconds(60));
+
+    // Establish a connection to the server.
+    s.connect(argv[1], "http");
+    if (!s)
+    {
+      std::cout << "Unable to connect: " << s.error().message() << "\n";
+      return 1;
+    }
+
+    // Send the request. We specify the "Connection: close" header so that the
+    // server will close the socket after transmitting the response. This will
+    // allow us to treat all data up until the EOF as the content.
+    s << "GET " << argv[2] << " HTTP/1.0\r\n";
+    s << "Host: " << argv[1] << "\r\n";
+    s << "Accept: */*\r\n";
+    s << "Connection: close\r\n\r\n";
+
+    // By default, the stream is tied with itself. This means that the stream
+    // automatically flush the buffered output before attempting a read. It is
+    // not necessary not explicitly flush the stream at this point.
+
+    // Check that response is OK.
+    std::string http_version;
+    s >> http_version;
+    unsigned int status_code;
+    s >> status_code;
+    std::string status_message;
+    std::getline(s, status_message);
+    if (!s || http_version.substr(0, 5) != "HTTP/")
+    {
+      std::cout << "Invalid response\n";
+      return 1;
+    }
+    if (status_code != 200)
+    {
+      std::cout << "Response returned with status code " << status_code << "\n";
+      return 1;
+    }
+
+    // Process the response headers, which are terminated by a blank line.
+    std::string header;
+    while (std::getline(s, header) && header != "\r")
+      std::cout << header << "\n";
+    std::cout << "\n";
+
+    // Write the remaining data to output.
+    std::cout << s.rdbuf();
+  }
+  catch (std::exception& e)
+  {
+    std::cout << "Exception: " << e.what() << "\n";
+  }
+
+  return 0;
+}

doc/html/boost_asio/example/cpp03/local/connect_pair.cpp

@@ -0,0 +1,142 @@
+//
+// connect_pair.cpp
+// ~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <iostream>
+#include <string>
+#include <cctype>
+#include <boost/asio.hpp>
+#include <boost/thread/thread.hpp>
+#include <boost/array.hpp>
+#include <boost/bind/bind.hpp>
+
+#if defined(BOOST_ASIO_HAS_LOCAL_SOCKETS)
+
+using boost::asio::local::stream_protocol;
+
+class uppercase_filter
+{
+public:
+  uppercase_filter(boost::asio::io_context& io_context)
+    : socket_(io_context)
+  {
+  }
+
+  stream_protocol::socket& socket()
+  {
+    return socket_;
+  }
+
+  void start()
+  {
+    // Wait for request.
+    socket_.async_read_some(boost::asio::buffer(data_),
+        boost::bind(&uppercase_filter::handle_read,
+          this, boost::asio::placeholders::error,
+          boost::asio::placeholders::bytes_transferred));
+  }
+
+private:
+  void handle_read(const boost::system::error_code& ec, std::size_t size)
+  {
+    if (!ec)
+    {
+      // Compute result.
+      for (std::size_t i = 0; i < size; ++i)
+        data_[i] = std::toupper(data_[i]);
+
+      // Send result.
+      boost::asio::async_write(socket_, boost::asio::buffer(data_, size),
+          boost::bind(&uppercase_filter::handle_write,
+            this, boost::asio::placeholders::error));
+    }
+    else
+    {
+      throw boost::system::system_error(ec);
+    }
+  }
+
+  void handle_write(const boost::system::error_code& ec)
+  {
+    if (!ec)
+    {
+      // Wait for request.
+      socket_.async_read_some(boost::asio::buffer(data_),
+          boost::bind(&uppercase_filter::handle_read,
+            this, boost::asio::placeholders::error,
+            boost::asio::placeholders::bytes_transferred));
+    }
+    else
+    {
+      throw boost::system::system_error(ec);
+    }
+  }
+
+  stream_protocol::socket socket_;
+  boost::array<char, 512> data_;
+};
+
+void run(boost::asio::io_context* io_context)
+{
+  try
+  {
+    io_context->run();
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << "Exception in thread: " << e.what() << "\n";
+    std::exit(1);
+  }
+}
+
+int main()
+{
+  try
+  {
+    boost::asio::io_context io_context;
+
+    // Create filter and establish a connection to it.
+    uppercase_filter filter(io_context);
+    stream_protocol::socket socket(io_context);
+    boost::asio::local::connect_pair(socket, filter.socket());
+    filter.start();
+
+    // The io_context runs in a background thread to perform filtering.
+    boost::thread thread(boost::bind(run, &io_context));
+
+    for (;;)
+    {
+      // Collect request from user.
+      std::cout << "Enter a string: ";
+      std::string request;
+      std::getline(std::cin, request);
+
+      // Send request to filter.
+      boost::asio::write(socket, boost::asio::buffer(request));
+
+      // Wait for reply from filter.
+      std::vector<char> reply(request.size());
+      boost::asio::read(socket, boost::asio::buffer(reply));
+
+      // Show reply to user.
+      std::cout << "Result: ";
+      std::cout.write(&reply[0], request.size());
+      std::cout << std::endl;
+    }
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << "Exception: " << e.what() << "\n";
+    std::exit(1);
+  }
+}
+
+#else // defined(BOOST_ASIO_HAS_LOCAL_SOCKETS)
+# error Local sockets not available on this platform.
+#endif // defined(BOOST_ASIO_HAS_LOCAL_SOCKETS)

doc/html/boost_asio/example/cpp03/local/iostream_client.cpp

@@ -0,0 +1,62 @@
+//
+// stream_client.cpp
+// ~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <cstring>
+#include <iostream>
+#include <boost/asio.hpp>
+
+#if defined(BOOST_ASIO_HAS_LOCAL_SOCKETS)
+
+using boost::asio::local::stream_protocol;
+
+enum { max_length = 1024 };
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    if (argc != 2)
+    {
+      std::cerr << "Usage: iostream_client <file>\n";
+      return 1;
+    }
+
+    stream_protocol::endpoint ep(argv[1]);
+    stream_protocol::iostream s(ep);
+    if (!s)
+    {
+      std::cerr << "Unable to connect: " << s.error().message() << std::endl;
+      return 1;
+    }
+
+    using namespace std; // For strlen.
+    std::cout << "Enter message: ";
+    char request[max_length];
+    std::cin.getline(request, max_length);
+    size_t length = strlen(request);
+    s << request;
+
+    char reply[max_length];
+    s.read(reply, length);
+    std::cout << "Reply is: ";
+    std::cout.write(reply, length);
+    std::cout << "\n";
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << "Exception: " << e.what() << "\n";
+  }
+
+  return 0;
+}
+
+#else // defined(BOOST_ASIO_HAS_LOCAL_SOCKETS)
+# error Local sockets not available on this platform.
+#endif // defined(BOOST_ASIO_HAS_LOCAL_SOCKETS)

doc/html/boost_asio/example/cpp03/local/stream_client.cpp

@@ -0,0 +1,61 @@
+//
+// stream_client.cpp
+// ~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <cstdlib>
+#include <cstring>
+#include <iostream>
+#include <boost/asio.hpp>
+
+#if defined(BOOST_ASIO_HAS_LOCAL_SOCKETS)
+
+using boost::asio::local::stream_protocol;
+
+enum { max_length = 1024 };
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    if (argc != 2)
+    {
+      std::cerr << "Usage: stream_client <file>\n";
+      return 1;
+    }
+
+    boost::asio::io_context io_context;
+
+    stream_protocol::socket s(io_context);
+    s.connect(stream_protocol::endpoint(argv[1]));
+
+    using namespace std; // For strlen.
+    std::cout << "Enter message: ";
+    char request[max_length];
+    std::cin.getline(request, max_length);
+    size_t request_length = strlen(request);
+    boost::asio::write(s, boost::asio::buffer(request, request_length));
+
+    char reply[max_length];
+    size_t reply_length = boost::asio::read(s,
+        boost::asio::buffer(reply, request_length));
+    std::cout << "Reply is: ";
+    std::cout.write(reply, reply_length);
+    std::cout << "\n";
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << "Exception: " << e.what() << "\n";
+  }
+
+  return 0;
+}
+
+#else // defined(BOOST_ASIO_HAS_LOCAL_SOCKETS)
+# error Local sockets not available on this platform.
+#endif // defined(BOOST_ASIO_HAS_LOCAL_SOCKETS)

doc/html/boost_asio/example/cpp03/local/stream_server.cpp

@@ -0,0 +1,141 @@
+//
+// stream_server.cpp
+// ~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <cstdio>
+#include <iostream>
+#include <boost/array.hpp>
+#include <boost/bind/bind.hpp>
+#include <boost/enable_shared_from_this.hpp>
+#include <boost/shared_ptr.hpp>
+#include <boost/asio.hpp>
+
+#if defined(BOOST_ASIO_HAS_LOCAL_SOCKETS)
+
+using boost::asio::local::stream_protocol;
+
+class session
+  : public boost::enable_shared_from_this<session>
+{
+public:
+  session(boost::asio::io_context& io_context)
+    : socket_(io_context)
+  {
+  }
+
+  stream_protocol::socket& socket()
+  {
+    return socket_;
+  }
+
+  void start()
+  {
+    socket_.async_read_some(boost::asio::buffer(data_),
+        boost::bind(&session::handle_read,
+          shared_from_this(),
+          boost::asio::placeholders::error,
+          boost::asio::placeholders::bytes_transferred));
+  }
+
+  void handle_read(const boost::system::error_code& error,
+      size_t bytes_transferred)
+  {
+    if (!error)
+    {
+      boost::asio::async_write(socket_,
+          boost::asio::buffer(data_, bytes_transferred),
+          boost::bind(&session::handle_write,
+            shared_from_this(),
+            boost::asio::placeholders::error));
+    }
+  }
+
+  void handle_write(const boost::system::error_code& error)
+  {
+    if (!error)
+    {
+      socket_.async_read_some(boost::asio::buffer(data_),
+          boost::bind(&session::handle_read,
+            shared_from_this(),
+            boost::asio::placeholders::error,
+            boost::asio::placeholders::bytes_transferred));
+    }
+  }
+
+private:
+  // The socket used to communicate with the client.
+  stream_protocol::socket socket_;
+
+  // Buffer used to store data received from the client.
+  boost::array<char, 1024> data_;
+};
+
+typedef boost::shared_ptr<session> session_ptr;
+
+class server
+{
+public:
+  server(boost::asio::io_context& io_context, const std::string& file)
+    : io_context_(io_context),
+      acceptor_(io_context, stream_protocol::endpoint(file))
+  {
+    session_ptr new_session(new session(io_context_));
+    acceptor_.async_accept(new_session->socket(),
+        boost::bind(&server::handle_accept, this, new_session,
+          boost::asio::placeholders::error));
+  }
+
+  void handle_accept(session_ptr new_session,
+      const boost::system::error_code& error)
+  {
+    if (!error)
+    {
+      new_session->start();
+    }
+
+    new_session.reset(new session(io_context_));
+    acceptor_.async_accept(new_session->socket(),
+        boost::bind(&server::handle_accept, this, new_session,
+          boost::asio::placeholders::error));
+  }
+
+private:
+  boost::asio::io_context& io_context_;
+  stream_protocol::acceptor acceptor_;
+};
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    if (argc != 2)
+    {
+      std::cerr << "Usage: stream_server <file>\n";
+      std::cerr << "*** WARNING: existing file is removed ***\n";
+      return 1;
+    }
+
+    boost::asio::io_context io_context;
+
+    std::remove(argv[1]);
+    server s(io_context, argv[1]);
+
+    io_context.run();
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << "Exception: " << e.what() << "\n";
+  }
+
+  return 0;
+}
+
+#else // defined(BOOST_ASIO_HAS_LOCAL_SOCKETS)
+# error Local sockets not available on this platform.
+#endif // defined(BOOST_ASIO_HAS_LOCAL_SOCKETS)

doc/html/boost_asio/example/cpp03/multicast/receiver.cpp

@@ -0,0 +1,93 @@
+//
+// receiver.cpp
+// ~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <iostream>
+#include <string>
+#include <boost/asio.hpp>
+#include "boost/bind/bind.hpp"
+
+const short multicast_port = 30001;
+
+class receiver
+{
+public:
+  receiver(boost::asio::io_context& io_context,
+      const boost::asio::ip::address& listen_address,
+      const boost::asio::ip::address& multicast_address)
+    : socket_(io_context)
+  {
+    // Create the socket so that multiple may be bound to the same address.
+    boost::asio::ip::udp::endpoint listen_endpoint(
+        listen_address, multicast_port);
+    socket_.open(listen_endpoint.protocol());
+    socket_.set_option(boost::asio::ip::udp::socket::reuse_address(true));
+    socket_.bind(listen_endpoint);
+
+    // Join the multicast group.
+    socket_.set_option(
+        boost::asio::ip::multicast::join_group(multicast_address));
+
+    socket_.async_receive_from(
+        boost::asio::buffer(data_, max_length), sender_endpoint_,
+        boost::bind(&receiver::handle_receive_from, this,
+          boost::asio::placeholders::error,
+          boost::asio::placeholders::bytes_transferred));
+  }
+
+  void handle_receive_from(const boost::system::error_code& error,
+      size_t bytes_recvd)
+  {
+    if (!error)
+    {
+      std::cout.write(data_, bytes_recvd);
+      std::cout << std::endl;
+
+      socket_.async_receive_from(
+          boost::asio::buffer(data_, max_length), sender_endpoint_,
+          boost::bind(&receiver::handle_receive_from, this,
+            boost::asio::placeholders::error,
+            boost::asio::placeholders::bytes_transferred));
+    }
+  }
+
+private:
+  boost::asio::ip::udp::socket socket_;
+  boost::asio::ip::udp::endpoint sender_endpoint_;
+  enum { max_length = 1024 };
+  char data_[max_length];
+};
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    if (argc != 3)
+    {
+      std::cerr << "Usage: receiver <listen_address> <multicast_address>\n";
+      std::cerr << "  For IPv4, try:\n";
+      std::cerr << "    receiver 0.0.0.0 239.255.0.1\n";
+      std::cerr << "  For IPv6, try:\n";
+      std::cerr << "    receiver 0::0 ff31::8000:1234\n";
+      return 1;
+    }
+
+    boost::asio::io_context io_context;
+    receiver r(io_context,
+        boost::asio::ip::make_address(argv[1]),
+        boost::asio::ip::make_address(argv[2]));
+    io_context.run();
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << "Exception: " << e.what() << "\n";
+  }
+
+  return 0;
+}

doc/html/boost_asio/example/cpp03/multicast/sender.cpp

@@ -0,0 +1,98 @@
+//
+// sender.cpp
+// ~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <iostream>
+#include <sstream>
+#include <string>
+#include <boost/asio.hpp>
+#include "boost/bind/bind.hpp"
+
+const short multicast_port = 30001;
+const int max_message_count = 10;
+
+class sender
+{
+public:
+  sender(boost::asio::io_context& io_context,
+      const boost::asio::ip::address& multicast_address)
+    : endpoint_(multicast_address, multicast_port),
+      socket_(io_context, endpoint_.protocol()),
+      timer_(io_context),
+      message_count_(0)
+  {
+    std::ostringstream os;
+    os << "Message " << message_count_++;
+    message_ = os.str();
+
+    socket_.async_send_to(
+        boost::asio::buffer(message_), endpoint_,
+        boost::bind(&sender::handle_send_to, this,
+          boost::asio::placeholders::error));
+  }
+
+  void handle_send_to(const boost::system::error_code& error)
+  {
+    if (!error && message_count_ < max_message_count)
+    {
+      timer_.expires_after(boost::asio::chrono::seconds(1));
+      timer_.async_wait(
+          boost::bind(&sender::handle_timeout, this,
+            boost::asio::placeholders::error));
+    }
+  }
+
+  void handle_timeout(const boost::system::error_code& error)
+  {
+    if (!error)
+    {
+      std::ostringstream os;
+      os << "Message " << message_count_++;
+      message_ = os.str();
+
+      socket_.async_send_to(
+          boost::asio::buffer(message_), endpoint_,
+          boost::bind(&sender::handle_send_to, this,
+            boost::asio::placeholders::error));
+    }
+  }
+
+private:
+  boost::asio::ip::udp::endpoint endpoint_;
+  boost::asio::ip::udp::socket socket_;
+  boost::asio::steady_timer timer_;
+  int message_count_;
+  std::string message_;
+};
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    if (argc != 2)
+    {
+      std::cerr << "Usage: sender <multicast_address>\n";
+      std::cerr << "  For IPv4, try:\n";
+      std::cerr << "    sender 239.255.0.1\n";
+      std::cerr << "  For IPv6, try:\n";
+      std::cerr << "    sender ff31::8000:1234\n";
+      return 1;
+    }
+
+    boost::asio::io_context io_context;
+    sender s(io_context, boost::asio::ip::make_address(argv[1]));
+    io_context.run();
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << "Exception: " << e.what() << "\n";
+  }
+
+  return 0;
+}

doc/html/boost_asio/example/cpp03/nonblocking/third_party_lib.cpp

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+//
+// third_party_lib.cpp
+// ~~~~~~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <boost/asio.hpp>
+#include <boost/array.hpp>
+#include <boost/bind/bind.hpp>
+#include <boost/shared_ptr.hpp>
+#include <boost/enable_shared_from_this.hpp>
+#include <iostream>
+
+using boost::asio::ip::tcp;
+
+namespace third_party_lib {
+
+// Simulation of a third party library that wants to perform read and write
+// operations directly on a socket. It needs to be polled to determine whether
+// it requires a read or write operation, and notified when the socket is ready
+// for reading or writing.
+class session
+{
+public:
+  session(tcp::socket& socket)
+    : socket_(socket),
+      state_(reading)
+  {
+  }
+
+  // Returns true if the third party library wants to be notified when the
+  // socket is ready for reading.
+  bool want_read() const
+  {
+    return state_ == reading;
+  }
+
+  // Notify that third party library that it should perform its read operation.
+  void do_read(boost::system::error_code& ec)
+  {
+    if (std::size_t len = socket_.read_some(boost::asio::buffer(data_), ec))
+    {
+      write_buffer_ = boost::asio::buffer(data_, len);
+      state_ = writing;
+    }
+  }
+
+  // Returns true if the third party library wants to be notified when the
+  // socket is ready for writing.
+  bool want_write() const
+  {
+    return state_ == writing;
+  }
+
+  // Notify that third party library that it should perform its write operation.
+  void do_write(boost::system::error_code& ec)
+  {
+    if (std::size_t len = socket_.write_some(
+          boost::asio::buffer(write_buffer_), ec))
+    {
+      write_buffer_ = write_buffer_ + len;
+      state_ = boost::asio::buffer_size(write_buffer_) > 0 ? writing : reading;
+    }
+  }
+
+private:
+  tcp::socket& socket_;
+  enum { reading, writing } state_;
+  boost::array<char, 128> data_;
+  boost::asio::const_buffer write_buffer_;
+};
+
+} // namespace third_party_lib
+
+// The glue between asio's sockets and the third party library.
+class connection
+  : public boost::enable_shared_from_this<connection>
+{
+public:
+  typedef boost::shared_ptr<connection> pointer;
+
+  static pointer create(const boost::asio::any_io_executor& ex)
+  {
+    return pointer(new connection(ex));
+  }
+
+  tcp::socket& socket()
+  {
+    return socket_;
+  }
+
+  void start()
+  {
+    // Put the socket into non-blocking mode.
+    socket_.non_blocking(true);
+
+    start_operations();
+  }
+
+private:
+  connection(const boost::asio::any_io_executor& ex)
+    : socket_(ex),
+      session_impl_(socket_),
+      read_in_progress_(false),
+      write_in_progress_(false)
+  {
+  }
+
+  void start_operations()
+  {
+    // Start a read operation if the third party library wants one.
+    if (session_impl_.want_read() && !read_in_progress_)
+    {
+      read_in_progress_ = true;
+      socket_.async_wait(tcp::socket::wait_read,
+          boost::bind(&connection::handle_read,
+            shared_from_this(),
+            boost::asio::placeholders::error));
+    }
+
+    // Start a write operation if the third party library wants one.
+    if (session_impl_.want_write() && !write_in_progress_)
+    {
+      write_in_progress_ = true;
+      socket_.async_wait(tcp::socket::wait_write,
+          boost::bind(&connection::handle_write,
+            shared_from_this(),
+            boost::asio::placeholders::error));
+    }
+  }
+
+  void handle_read(boost::system::error_code ec)
+  {
+    read_in_progress_ = false;
+
+    // Notify third party library that it can perform a read.
+    if (!ec)
+      session_impl_.do_read(ec);
+
+    // The third party library successfully performed a read on the socket.
+    // Start new read or write operations based on what it now wants.
+    if (!ec || ec == boost::asio::error::would_block)
+      start_operations();
+
+    // Otherwise, an error occurred. Closing the socket cancels any outstanding
+    // asynchronous read or write operations. The connection object will be
+    // destroyed automatically once those outstanding operations complete.
+    else
+      socket_.close();
+  }
+
+  void handle_write(boost::system::error_code ec)
+  {
+    write_in_progress_ = false;
+
+    // Notify third party library that it can perform a write.
+    if (!ec)
+      session_impl_.do_write(ec);
+
+    // The third party library successfully performed a write on the socket.
+    // Start new read or write operations based on what it now wants.
+    if (!ec || ec == boost::asio::error::would_block)
+      start_operations();
+
+    // Otherwise, an error occurred. Closing the socket cancels any outstanding
+    // asynchronous read or write operations. The connection object will be
+    // destroyed automatically once those outstanding operations complete.
+    else
+      socket_.close();
+  }
+
+private:
+  tcp::socket socket_;
+  third_party_lib::session session_impl_;
+  bool read_in_progress_;
+  bool write_in_progress_;
+};
+
+class server
+{
+public:
+  server(boost::asio::io_context& io_context, unsigned short port)
+    : acceptor_(io_context, tcp::endpoint(tcp::v4(), port))
+  {
+    start_accept();
+  }
+
+private:
+  void start_accept()
+  {
+    connection::pointer new_connection =
+      connection::create(acceptor_.get_executor());
+
+    acceptor_.async_accept(new_connection->socket(),
+        boost::bind(&server::handle_accept, this, new_connection,
+          boost::asio::placeholders::error));
+  }
+
+  void handle_accept(connection::pointer new_connection,
+      const boost::system::error_code& error)
+  {
+    if (!error)
+    {
+      new_connection->start();
+    }
+
+    start_accept();
+  }
+
+  tcp::acceptor acceptor_;
+};
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    if (argc != 2)
+    {
+      std::cerr << "Usage: third_party_lib <port>\n";
+      return 1;
+    }
+
+    boost::asio::io_context io_context;
+
+    using namespace std; // For atoi.
+    server s(io_context, atoi(argv[1]));
+
+    io_context.run();
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << "Exception: " << e.what() << "\n";
+  }
+
+  return 0;
+}

doc/html/boost_asio/example/cpp03/porthopper/client.cpp

@@ -0,0 +1,192 @@
+//
+// client.cpp
+// ~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <boost/asio.hpp>
+#include <boost/lambda/lambda.hpp>
+#include <boost/lambda/bind.hpp>
+#include <boost/lambda/if.hpp>
+#include <boost/shared_ptr.hpp>
+#include <algorithm>
+#include <cstdlib>
+#include <exception>
+#include <iostream>
+#include <string>
+#include "protocol.hpp"
+
+using namespace boost;
+using boost::asio::ip::tcp;
+using boost::asio::ip::udp;
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    if (argc != 3)
+    {
+      std::cerr << "Usage: client <host> <port>\n";
+      return 1;
+    }
+    using namespace std; // For atoi.
+    std::string host_name = argv[1];
+    std::string port = argv[2];
+
+    boost::asio::io_context io_context;
+
+    // Determine the location of the server.
+    tcp::resolver resolver(io_context);
+    tcp::endpoint remote_endpoint = *resolver.resolve(host_name, port).begin();
+
+    // Establish the control connection to the server.
+    tcp::socket control_socket(io_context);
+    control_socket.connect(remote_endpoint);
+
+    // Create a datagram socket to receive data from the server.
+    boost::shared_ptr<udp::socket> data_socket(
+        new udp::socket(io_context, udp::endpoint(udp::v4(), 0)));
+
+    // Determine what port we will receive data on.
+    udp::endpoint data_endpoint = data_socket->local_endpoint();
+
+    // Ask the server to start sending us data.
+    control_request start = control_request::start(data_endpoint.port());
+    boost::asio::write(control_socket, start.to_buffers());
+
+    unsigned long last_frame_number = 0;
+    for (;;)
+    {
+      // Receive 50 messages on the current data socket.
+      for (int i = 0; i < 50; ++i)
+      {
+        // Receive a frame from the server.
+        frame f;
+        data_socket->receive(f.to_buffers(), 0);
+        if (f.number() > last_frame_number)
+        {
+          last_frame_number = f.number();
+          std::cout << "\n" << f.payload();
+        }
+      }
+
+      // Time to switch to a new socket. To ensure seamless handover we will
+      // continue to receive packets using the old socket until data arrives on
+      // the new one.
+      std::cout << " Starting renegotiation";
+
+      // Create the new data socket.
+      boost::shared_ptr<udp::socket> new_data_socket(
+          new udp::socket(io_context, udp::endpoint(udp::v4(), 0)));
+
+      // Determine the new port we will use to receive data.
+      udp::endpoint new_data_endpoint = new_data_socket->local_endpoint();
+
+      // Ask the server to switch over to the new port.
+      control_request change = control_request::change(
+          data_endpoint.port(), new_data_endpoint.port());
+      boost::system::error_code control_result;
+      boost::asio::async_write(control_socket, change.to_buffers(),
+          (
+            lambda::var(control_result) = lambda::_1
+          ));
+
+      // Try to receive a frame from the server on the new data socket. If we
+      // successfully receive a frame on this new data socket we can consider
+      // the renegotation complete. In that case we will close the old data
+      // socket, which will cause any outstanding receive operation on it to be
+      // cancelled.
+      frame f1;
+      boost::system::error_code new_data_socket_result;
+      new_data_socket->async_receive(f1.to_buffers(),
+          (
+            // Note: lambda::_1 is the first argument to the callback handler,
+            // which in this case is the error code for the operation.
+            lambda::var(new_data_socket_result) = lambda::_1,
+            lambda::if_(!lambda::_1)
+            [
+              // We have successfully received a frame on the new data socket,
+              // so we can close the old data socket. This will cancel any
+              // outstanding receive operation on the old data socket.
+              lambda::var(data_socket) = boost::shared_ptr<udp::socket>()
+            ]
+          ));
+
+      // This loop will continue until we have successfully completed the
+      // renegotiation (i.e. received a frame on the new data socket), or some
+      // unrecoverable error occurs.
+      bool done = false;
+      while (!done)
+      {
+        // Even though we're performing a renegotation, we want to continue
+        // receiving data as smoothly as possible. Therefore we will continue to
+        // try to receive a frame from the server on the old data socket. If we
+        // receive a frame on this socket we will interrupt the io_context,
+        // print the frame, and resume waiting for the other operations to
+        // complete.
+        frame f2;
+        done = true; // Let's be optimistic.
+        if (data_socket) // Might have been closed by new_data_socket's handler.
+        {
+          data_socket->async_receive(f2.to_buffers(), 0,
+              (
+                lambda::if_(!lambda::_1)
+                [
+                  // We have successfully received a frame on the old data
+                  // socket. Stop the io_context so that we can print it.
+                  lambda::bind(&boost::asio::io_context::stop, &io_context),
+                  lambda::var(done) = false
+                ]
+              ));
+        }
+
+        // Run the operations in parallel. This will block until all operations
+        // have finished, or until the io_context is interrupted. (No threads!)
+        io_context.restart();
+        io_context.run();
+
+        // If the io_context.run() was interrupted then we have received a frame
+        // on the old data socket. We need to keep waiting for the renegotation
+        // operations to complete.
+        if (!done)
+        {
+          if (f2.number() > last_frame_number)
+          {
+            last_frame_number = f2.number();
+            std::cout << "\n" << f2.payload();
+          }
+        }
+      }
+
+      // Since the loop has finished, we have either successfully completed
+      // the renegotation, or an error has occurred. First we'll check for
+      // errors.
+      if (control_result)
+        throw boost::system::system_error(control_result);
+      if (new_data_socket_result)
+        throw boost::system::system_error(new_data_socket_result);
+
+      // If we get here it means we have successfully started receiving data on
+      // the new data socket. This new data socket will be used from now on
+      // (until the next time we renegotiate).
+      std::cout << " Renegotiation complete";
+      data_socket = new_data_socket;
+      data_endpoint = new_data_endpoint;
+      if (f1.number() > last_frame_number)
+      {
+        last_frame_number = f1.number();
+        std::cout << "\n" << f1.payload();
+      }
+    }
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << "Exception: " << e.what() << std::endl;
+  }
+
+  return 0;
+}

doc/html/boost_asio/example/cpp03/porthopper/protocol.hpp

@@ -0,0 +1,156 @@
+//
+// protocol.hpp
+// ~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef PORTHOPPER_PROTOCOL_HPP
+#define PORTHOPPER_PROTOCOL_HPP
+
+#include <boost/array.hpp>
+#include <boost/asio.hpp>
+#include <cstring>
+#include <iomanip>
+#include <string>
+#include <strstream>
+
+// This request is sent by the client to the server over a TCP connection.
+// The client uses it to perform three functions:
+// - To request that data start being sent to a given port.
+// - To request that data is no longer sent to a given port.
+// - To change the target port to another.
+class control_request
+{
+public:
+  // Construct an empty request. Used when receiving.
+  control_request()
+  {
+  }
+
+  // Create a request to start sending data to a given port.
+  static const control_request start(unsigned short port)
+  {
+    return control_request(0, port);
+  }
+
+  // Create a request to stop sending data to a given port.
+  static const control_request stop(unsigned short port)
+  {
+    return control_request(port, 0);
+  }
+
+  // Create a request to change the port that data is sent to.
+  static const control_request change(
+      unsigned short old_port, unsigned short new_port)
+  {
+    return control_request(old_port, new_port);
+  }
+
+  // Get the old port. Returns 0 for start requests.
+  unsigned short old_port() const
+  {
+    std::istrstream is(data_, encoded_port_size);
+    unsigned short port = 0;
+    is >> std::setw(encoded_port_size) >> std::hex >> port;
+    return port;
+  }
+
+  // Get the new port. Returns 0 for stop requests.
+  unsigned short new_port() const
+  {
+    std::istrstream is(data_ + encoded_port_size, encoded_port_size);
+    unsigned short port = 0;
+    is >> std::setw(encoded_port_size) >> std::hex >> port;
+    return port;
+  }
+
+  // Obtain buffers for reading from or writing to a socket.
+  boost::array<boost::asio::mutable_buffer, 1> to_buffers()
+  {
+    boost::array<boost::asio::mutable_buffer, 1> buffers
+      = { { boost::asio::buffer(data_) } };
+    return buffers;
+  }
+
+private:
+  // Construct with specified old and new ports.
+  control_request(unsigned short old_port_number,
+      unsigned short new_port_number)
+  {
+    std::ostrstream os(data_, control_request_size);
+    os << std::setw(encoded_port_size) << std::hex << old_port_number;
+    os << std::setw(encoded_port_size) << std::hex << new_port_number;
+  }
+
+  // The length in bytes of a control_request and its components.
+  enum
+  {
+    encoded_port_size = 4, // 16-bit port in hex.
+    control_request_size = encoded_port_size * 2
+  };
+
+  // The encoded request data.
+  char data_[control_request_size];
+};
+
+// This frame is sent from the server to subscribed clients over UDP.
+class frame
+{
+public:
+  // The maximum allowable length of the payload.
+  enum { payload_size = 32 };
+
+  // Construct an empty frame. Used when receiving.
+  frame()
+  {
+  }
+
+  // Construct a frame with specified frame number and payload.
+  frame(unsigned long frame_number, const std::string& payload_data)
+  {
+    std::ostrstream os(data_, frame_size);
+    os << std::setw(encoded_number_size) << std::hex << frame_number;
+    os << std::setw(payload_size)
+      << std::setfill(' ') << payload_data.substr(0, payload_size);
+  }
+
+  // Get the frame number.
+  unsigned long number() const
+  {
+    std::istrstream is(data_, encoded_number_size);
+    unsigned long frame_number = 0;
+    is >> std::setw(encoded_number_size) >> std::hex >> frame_number;
+    return frame_number;
+  }
+
+  // Get the payload data.
+  const std::string payload() const
+  {
+    return std::string(data_ + encoded_number_size, payload_size);
+  }
+
+  // Obtain buffers for reading from or writing to a socket.
+  boost::array<boost::asio::mutable_buffer, 1> to_buffers()
+  {
+    boost::array<boost::asio::mutable_buffer, 1> buffers
+      = { { boost::asio::buffer(data_) } };
+    return buffers;
+  }
+
+private:
+  // The length in bytes of a frame and its components.
+  enum
+  {
+    encoded_number_size = 8, // Frame number in hex.
+    frame_size = encoded_number_size + payload_size
+  };
+
+  // The encoded frame data.
+  char data_[frame_size];
+};
+
+#endif // PORTHOPPER_PROTOCOL_HPP

doc/html/boost_asio/example/cpp03/porthopper/server.cpp

@@ -0,0 +1,187 @@
+//
+// server.cpp
+// ~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <boost/asio.hpp>
+#include <boost/bind/bind.hpp>
+#include <boost/shared_ptr.hpp>
+#include <cmath>
+#include <cstdlib>
+#include <exception>
+#include <iostream>
+#include <set>
+#include "protocol.hpp"
+
+using boost::asio::ip::tcp;
+using boost::asio::ip::udp;
+
+typedef boost::shared_ptr<tcp::socket> tcp_socket_ptr;
+typedef boost::shared_ptr<boost::asio::steady_timer> timer_ptr;
+typedef boost::shared_ptr<control_request> control_request_ptr;
+
+class server
+{
+public:
+  // Construct the server to wait for incoming control connections.
+  server(boost::asio::io_context& io_context, unsigned short port)
+    : acceptor_(io_context, tcp::endpoint(tcp::v4(), port)),
+      timer_(io_context),
+      udp_socket_(io_context, udp::endpoint(udp::v4(), 0)),
+      next_frame_number_(1)
+  {
+    // Start waiting for a new control connection.
+    tcp_socket_ptr new_socket(new tcp::socket(acceptor_.get_executor()));
+    acceptor_.async_accept(*new_socket,
+        boost::bind(&server::handle_accept, this,
+          boost::asio::placeholders::error, new_socket));
+
+    // Start the timer used to generate outgoing frames.
+    timer_.expires_after(boost::asio::chrono::milliseconds(100));
+    timer_.async_wait(boost::bind(&server::handle_timer, this));
+  }
+
+  // Handle a new control connection.
+  void handle_accept(const boost::system::error_code& ec, tcp_socket_ptr socket)
+  {
+    if (!ec)
+    {
+      // Start receiving control requests on the connection.
+      control_request_ptr request(new control_request);
+      boost::asio::async_read(*socket, request->to_buffers(),
+          boost::bind(&server::handle_control_request, this,
+            boost::asio::placeholders::error, socket, request));
+    }
+
+    // Start waiting for a new control connection.
+    tcp_socket_ptr new_socket(new tcp::socket(acceptor_.get_executor()));
+    acceptor_.async_accept(*new_socket,
+        boost::bind(&server::handle_accept, this,
+          boost::asio::placeholders::error, new_socket));
+  }
+
+  // Handle a new control request.
+  void handle_control_request(const boost::system::error_code& ec,
+      tcp_socket_ptr socket, control_request_ptr request)
+  {
+    if (!ec)
+    {
+      // Delay handling of the control request to simulate network latency.
+      timer_ptr delay_timer(
+          new boost::asio::steady_timer(acceptor_.get_executor()));
+      delay_timer->expires_after(boost::asio::chrono::seconds(2));
+      delay_timer->async_wait(
+          boost::bind(&server::handle_control_request_timer, this,
+            socket, request, delay_timer));
+    }
+  }
+
+  void handle_control_request_timer(tcp_socket_ptr socket,
+      control_request_ptr request, timer_ptr /*delay_timer*/)
+  {
+    // Determine what address this client is connected from, since
+    // subscriptions must be stored on the server as a complete endpoint, not
+    // just a port. We use the non-throwing overload of remote_endpoint() since
+    // it may fail if the socket is no longer connected.
+    boost::system::error_code ec;
+    tcp::endpoint remote_endpoint = socket->remote_endpoint(ec);
+    if (!ec)
+    {
+      // Remove old port subscription, if any.
+      if (unsigned short old_port = request->old_port())
+      {
+        udp::endpoint old_endpoint(remote_endpoint.address(), old_port);
+        subscribers_.erase(old_endpoint);
+        std::cout << "Removing subscription " << old_endpoint << std::endl;
+      }
+
+      // Add new port subscription, if any.
+      if (unsigned short new_port = request->new_port())
+      {
+        udp::endpoint new_endpoint(remote_endpoint.address(), new_port);
+        subscribers_.insert(new_endpoint);
+        std::cout << "Adding subscription " << new_endpoint << std::endl;
+      }
+    }
+
+    // Wait for next control request on this connection.
+    boost::asio::async_read(*socket, request->to_buffers(),
+        boost::bind(&server::handle_control_request, this,
+          boost::asio::placeholders::error, socket, request));
+  }
+
+  // Every time the timer fires we will generate a new frame and send it to all
+  // subscribers.
+  void handle_timer()
+  {
+    // Generate payload.
+    double x = next_frame_number_ * 0.2;
+    double y = std::sin(x);
+    int char_index = static_cast<int>((y + 1.0) * (frame::payload_size / 2));
+    std::string payload;
+    for (int i = 0; i < frame::payload_size; ++i)
+      payload += (i == char_index ? '*' : '.');
+
+    // Create the frame to be sent to all subscribers.
+    frame f(next_frame_number_++, payload);
+
+    // Send frame to all subscribers. We can use synchronous calls here since
+    // UDP send operations typically do not block.
+    std::set<udp::endpoint>::iterator j;
+    for (j = subscribers_.begin(); j != subscribers_.end(); ++j)
+    {
+      boost::system::error_code ec;
+      udp_socket_.send_to(f.to_buffers(), *j, 0, ec);
+    }
+
+    // Wait for next timeout.
+    timer_.expires_after(boost::asio::chrono::milliseconds(100));
+    timer_.async_wait(boost::bind(&server::handle_timer, this));
+  }
+
+private:
+  // The acceptor used to accept incoming control connections.
+  tcp::acceptor acceptor_;
+
+  // The timer used for generating data.
+  boost::asio::steady_timer timer_;
+
+  // The socket used to send data to subscribers.
+  udp::socket udp_socket_;
+
+  // The next frame number.
+  unsigned long next_frame_number_;
+
+  // The set of endpoints that are subscribed.
+  std::set<udp::endpoint> subscribers_;
+};
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    if (argc != 2)
+    {
+      std::cerr << "Usage: server <port>\n";
+      return 1;
+    }
+
+    boost::asio::io_context io_context;
+
+    using namespace std; // For atoi.
+    server s(io_context, atoi(argv[1]));
+
+    io_context.run();
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << "Exception: " << e.what() << std::endl;
+  }
+
+  return 0;
+}

doc/html/boost_asio/example/cpp03/serialization/client.cpp

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+//
+// client.cpp
+// ~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <boost/asio.hpp>
+#include <boost/bind/bind.hpp>
+#include <iostream>
+#include <vector>
+#include "connection.hpp" // Must come before boost/serialization headers.
+#include <boost/serialization/vector.hpp>
+#include "stock.hpp"
+
+namespace s11n_example {
+
+/// Downloads stock quote information from a server.
+class client
+{
+public:
+  /// Constructor starts the asynchronous connect operation.
+  client(boost::asio::io_context& io_context,
+      const std::string& host, const std::string& service)
+    : connection_(io_context.get_executor())
+  {
+    // Resolve the host name into an IP address.
+    boost::asio::ip::tcp::resolver resolver(io_context);
+    boost::asio::ip::tcp::resolver::query query(host, service);
+    boost::asio::ip::tcp::resolver::iterator endpoint_iterator =
+      resolver.resolve(query);
+
+    // Start an asynchronous connect operation.
+    boost::asio::async_connect(connection_.socket(), endpoint_iterator,
+        boost::bind(&client::handle_connect, this,
+          boost::asio::placeholders::error));
+  }
+
+  /// Handle completion of a connect operation.
+  void handle_connect(const boost::system::error_code& e)
+  {
+    if (!e)
+    {
+      // Successfully established connection. Start operation to read the list
+      // of stocks. The connection::async_read() function will automatically
+      // decode the data that is read from the underlying socket.
+      connection_.async_read(stocks_,
+          boost::bind(&client::handle_read, this,
+            boost::asio::placeholders::error));
+    }
+    else
+    {
+      // An error occurred. Log it and return. Since we are not starting a new
+      // operation the io_context will run out of work to do and the client will
+      // exit.
+      std::cerr << e.message() << std::endl;
+    }
+  }
+
+  /// Handle completion of a read operation.
+  void handle_read(const boost::system::error_code& e)
+  {
+    if (!e)
+    {
+      // Print out the data that was received.
+      for (std::size_t i = 0; i < stocks_.size(); ++i)
+      {
+        std::cout << "Stock number " << i << "\n";
+        std::cout << "  code: " << stocks_[i].code << "\n";
+        std::cout << "  name: " << stocks_[i].name << "\n";
+        std::cout << "  open_price: " << stocks_[i].open_price << "\n";
+        std::cout << "  high_price: " << stocks_[i].high_price << "\n";
+        std::cout << "  low_price: " << stocks_[i].low_price << "\n";
+        std::cout << "  last_price: " << stocks_[i].last_price << "\n";
+        std::cout << "  buy_price: " << stocks_[i].buy_price << "\n";
+        std::cout << "  buy_quantity: " << stocks_[i].buy_quantity << "\n";
+        std::cout << "  sell_price: " << stocks_[i].sell_price << "\n";
+        std::cout << "  sell_quantity: " << stocks_[i].sell_quantity << "\n";
+      }
+    }
+    else
+    {
+      // An error occurred.
+      std::cerr << e.message() << std::endl;
+    }
+
+    // Since we are not starting a new operation the io_context will run out of
+    // work to do and the client will exit.
+  }
+
+private:
+  /// The connection to the server.
+  connection connection_;
+
+  /// The data received from the server.
+  std::vector<stock> stocks_;
+};
+
+} // namespace s11n_example
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    // Check command line arguments.
+    if (argc != 3)
+    {
+      std::cerr << "Usage: client <host> <port>" << std::endl;
+      return 1;
+    }
+
+    boost::asio::io_context io_context;
+    s11n_example::client client(io_context, argv[1], argv[2]);
+    io_context.run();
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << e.what() << std::endl;
+  }
+
+  return 0;
+}

doc/html/boost_asio/example/cpp03/serialization/connection.hpp

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+//
+// connection.hpp
+// ~~~~~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#ifndef SERIALIZATION_CONNECTION_HPP
+#define SERIALIZATION_CONNECTION_HPP
+
+#include <boost/asio.hpp>
+#include <boost/archive/text_iarchive.hpp>
+#include <boost/archive/text_oarchive.hpp>
+#include <boost/bind/bind.hpp>
+#include <boost/shared_ptr.hpp>
+#include <boost/tuple/tuple.hpp>
+#include <iomanip>
+#include <string>
+#include <sstream>
+#include <vector>
+
+namespace s11n_example {
+
+/// The connection class provides serialization primitives on top of a socket.
+/**
+ * Each message sent using this class consists of:
+ * @li An 8-byte header containing the length of the serialized data in
+ * hexadecimal.
+ * @li The serialized data.
+ */
+class connection
+{
+public:
+  /// Constructor.
+  connection(const boost::asio::executor& ex)
+    : socket_(ex)
+  {
+  }
+
+  /// Get the underlying socket. Used for making a connection or for accepting
+  /// an incoming connection.
+  boost::asio::ip::tcp::socket& socket()
+  {
+    return socket_;
+  }
+
+  /// Asynchronously write a data structure to the socket.
+  template <typename T, typename Handler>
+  void async_write(const T& t, Handler handler)
+  {
+    // Serialize the data first so we know how large it is.
+    std::ostringstream archive_stream;
+    boost::archive::text_oarchive archive(archive_stream);
+    archive << t;
+    outbound_data_ = archive_stream.str();
+
+    // Format the header.
+    std::ostringstream header_stream;
+    header_stream << std::setw(header_length)
+      << std::hex << outbound_data_.size();
+    if (!header_stream || header_stream.str().size() != header_length)
+    {
+      // Something went wrong, inform the caller.
+      boost::system::error_code error(boost::asio::error::invalid_argument);
+      boost::asio::post(socket_.get_executor(), boost::bind(handler, error));
+      return;
+    }
+    outbound_header_ = header_stream.str();
+
+    // Write the serialized data to the socket. We use "gather-write" to send
+    // both the header and the data in a single write operation.
+    std::vector<boost::asio::const_buffer> buffers;
+    buffers.push_back(boost::asio::buffer(outbound_header_));
+    buffers.push_back(boost::asio::buffer(outbound_data_));
+    boost::asio::async_write(socket_, buffers, handler);
+  }
+
+  /// Asynchronously read a data structure from the socket.
+  template <typename T, typename Handler>
+  void async_read(T& t, Handler handler)
+  {
+    // Issue a read operation to read exactly the number of bytes in a header.
+    void (connection::*f)(
+        const boost::system::error_code&,
+        T&, boost::tuple<Handler>)
+      = &connection::handle_read_header<T, Handler>;
+    boost::asio::async_read(socket_, boost::asio::buffer(inbound_header_),
+        boost::bind(f,
+          this, boost::asio::placeholders::error, boost::ref(t),
+          boost::make_tuple(handler)));
+  }
+
+  /// Handle a completed read of a message header. The handler is passed using
+  /// a tuple since boost::bind seems to have trouble binding a function object
+  /// created using boost::bind as a parameter.
+  template <typename T, typename Handler>
+  void handle_read_header(const boost::system::error_code& e,
+      T& t, boost::tuple<Handler> handler)
+  {
+    if (e)
+    {
+      boost::get<0>(handler)(e);
+    }
+    else
+    {
+      // Determine the length of the serialized data.
+      std::istringstream is(std::string(inbound_header_, header_length));
+      std::size_t inbound_data_size = 0;
+      if (!(is >> std::hex >> inbound_data_size))
+      {
+        // Header doesn't seem to be valid. Inform the caller.
+        boost::system::error_code error(boost::asio::error::invalid_argument);
+        boost::get<0>(handler)(error);
+        return;
+      }
+
+      // Start an asynchronous call to receive the data.
+      inbound_data_.resize(inbound_data_size);
+      void (connection::*f)(
+          const boost::system::error_code&,
+          T&, boost::tuple<Handler>)
+        = &connection::handle_read_data<T, Handler>;
+      boost::asio::async_read(socket_, boost::asio::buffer(inbound_data_),
+        boost::bind(f, this,
+          boost::asio::placeholders::error, boost::ref(t), handler));
+    }
+  }
+
+  /// Handle a completed read of message data.
+  template <typename T, typename Handler>
+  void handle_read_data(const boost::system::error_code& e,
+      T& t, boost::tuple<Handler> handler)
+  {
+    if (e)
+    {
+      boost::get<0>(handler)(e);
+    }
+    else
+    {
+      // Extract the data structure from the data just received.
+      try
+      {
+        std::string archive_data(&inbound_data_[0], inbound_data_.size());
+        std::istringstream archive_stream(archive_data);
+        boost::archive::text_iarchive archive(archive_stream);
+        archive >> t;
+      }
+      catch (std::exception& e)
+      {
+        // Unable to decode data.
+        boost::system::error_code error(boost::asio::error::invalid_argument);
+        boost::get<0>(handler)(error);
+        return;
+      }
+
+      // Inform caller that data has been received ok.
+      boost::get<0>(handler)(e);
+    }
+  }
+
+private:
+  /// The underlying socket.
+  boost::asio::ip::tcp::socket socket_;
+
+  /// The size of a fixed length header.
+  enum { header_length = 8 };
+
+  /// Holds an outbound header.
+  std::string outbound_header_;
+
+  /// Holds the outbound data.
+  std::string outbound_data_;
+
+  /// Holds an inbound header.
+  char inbound_header_[header_length];
+
+  /// Holds the inbound data.
+  std::vector<char> inbound_data_;
+};
+
+typedef boost::shared_ptr<connection> connection_ptr;
+
+} // namespace s11n_example
+
+#endif // SERIALIZATION_CONNECTION_HPP

doc/html/boost_asio/example/cpp03/serialization/server.cpp

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+//
+// server.cpp
+// ~~~~~~~~~~
+//
+// Copyright (c) 2003-2021 Christopher M. Kohlhoff (chris at kohlhoff dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+
+#include <boost/asio.hpp>
+#include <boost/bind/bind.hpp>
+#include <boost/lexical_cast.hpp>
+#include <iostream>
+#include <vector>
+#include "connection.hpp" // Must come before boost/serialization headers.
+#include <boost/serialization/vector.hpp>
+#include "stock.hpp"
+
+namespace s11n_example {
+
+/// Serves stock quote information to any client that connects to it.
+class server
+{
+public:
+  /// Constructor opens the acceptor and starts waiting for the first incoming
+  /// connection.
+  server(boost::asio::io_context& io_context, unsigned short port)
+    : acceptor_(io_context,
+        boost::asio::ip::tcp::endpoint(boost::asio::ip::tcp::v4(), port))
+  {
+    // Create the data to be sent to each client.
+    stock s;
+    s.code = "ABC";
+    s.name = "A Big Company";
+    s.open_price = 4.56;
+    s.high_price = 5.12;
+    s.low_price = 4.33;
+    s.last_price = 4.98;
+    s.buy_price = 4.96;
+    s.buy_quantity = 1000;
+    s.sell_price = 4.99;
+    s.sell_quantity = 2000;
+    stocks_.push_back(s);
+    s.code = "DEF";
+    s.name = "Developer Entertainment Firm";
+    s.open_price = 20.24;
+    s.high_price = 22.88;
+    s.low_price = 19.50;
+    s.last_price = 19.76;
+    s.buy_price = 19.72;
+    s.buy_quantity = 34000;
+    s.sell_price = 19.85;
+    s.sell_quantity = 45000;
+    stocks_.push_back(s);
+
+    // Start an accept operation for a new connection.
+    connection_ptr new_conn(new connection(acceptor_.get_executor()));
+    acceptor_.async_accept(new_conn->socket(),
+        boost::bind(&server::handle_accept, this,
+          boost::asio::placeholders::error, new_conn));
+  }
+
+  /// Handle completion of a accept operation.
+  void handle_accept(const boost::system::error_code& e, connection_ptr conn)
+  {
+    if (!e)
+    {
+      // Successfully accepted a new connection. Send the list of stocks to the
+      // client. The connection::async_write() function will automatically
+      // serialize the data structure for us.
+      conn->async_write(stocks_,
+          boost::bind(&server::handle_write, this,
+            boost::asio::placeholders::error, conn));
+    }
+
+    // Start an accept operation for a new connection.
+    connection_ptr new_conn(new connection(acceptor_.get_executor()));
+    acceptor_.async_accept(new_conn->socket(),
+        boost::bind(&server::handle_accept, this,
+          boost::asio::placeholders::error, new_conn));
+  }
+
+  /// Handle completion of a write operation.
+  void handle_write(const boost::system::error_code& e, connection_ptr conn)
+  {
+    // Nothing to do. The socket will be closed automatically when the last
+    // reference to the connection object goes away.
+  }
+
+private:
+  /// The acceptor object used to accept incoming socket connections.
+  boost::asio::ip::tcp::acceptor acceptor_;
+
+  /// The data to be sent to each client.
+  std::vector<stock> stocks_;
+};
+
+} // namespace s11n_example
+
+int main(int argc, char* argv[])
+{
+  try
+  {
+    // Check command line arguments.
+    if (argc != 2)
+    {
+      std::cerr << "Usage: server <port>" << std::endl;
+      return 1;
+    }
+    unsigned short port = boost::lexical_cast<unsigned short>(argv[1]);
+
+    boost::asio::io_context io_context;
+    s11n_example::server server(io_context, port);
+    io_context.run();
+  }
+  catch (std::exception& e)
+  {
+    std::cerr << e.what() << std::endl;
+  }
+
+  return 0;
+}