/*
 * libjingle
 * Copyright 2012, Google Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *  1. Redistributions of source code must retain the above copyright notice,
 *     this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright notice,
 *     this list of conditions and the following disclaimer in the documentation
 *     and/or other materials provided with the distribution.
 *  3. The name of the author may not be used to endorse or promote products
 *     derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "talk/p2p/base/turnport.h"

#include <functional>

#include "talk/base/asyncpacketsocket.h"
#include "talk/base/byteorder.h"
#include "talk/base/common.h"
#include "talk/base/logging.h"
#include "talk/base/nethelpers.h"
#include "talk/base/socketaddress.h"
#include "talk/base/stringencode.h"
#include "talk/p2p/base/common.h"
#include "talk/p2p/base/stun.h"

namespace cricket {

// TODO(juberti): Move to stun.h when relay messages have been renamed.
static const int TURN_ALLOCATE_REQUEST = STUN_ALLOCATE_REQUEST;
static const int TURN_ALLOCATE_ERROR_RESPONSE = STUN_ALLOCATE_ERROR_RESPONSE;

// TODO(juberti): Extract to turnmessage.h
static const int TURN_DEFAULT_PORT = 3478;
static const int TURN_CHANNEL_NUMBER_START = 0x4000;
static const int TURN_PERMISSION_TIMEOUT = 5 * 60 * 1000;  // 5 minutes

static const size_t TURN_CHANNEL_HEADER_SIZE = 4U;

inline bool IsTurnChannelData(uint16 msg_type) {
  return ((msg_type & 0xC000) == 0x4000);  // MSB are 0b01
}

static int GetRelayPreference(cricket::ProtocolType proto, bool secure) {
  int relay_preference = ICE_TYPE_PREFERENCE_RELAY;
  if (proto == cricket::PROTO_TCP) {
    relay_preference -= 1;
    if (secure)
      relay_preference -= 1;
  }

  ASSERT(relay_preference >= 0);
  return relay_preference;
}

class TurnAllocateRequest : public StunRequest {
 public:
  explicit TurnAllocateRequest(TurnPort* port);
  virtual void Prepare(StunMessage* request);
  virtual void OnResponse(StunMessage* response);
  virtual void OnErrorResponse(StunMessage* response);
  virtual void OnTimeout();

 private:
  // Handles authentication challenge from the server.
  void OnAuthChallenge(StunMessage* response, int code);
  void OnUnknownAttribute(StunMessage* response);

  TurnPort* port_;
};

class TurnRefreshRequest : public StunRequest {
 public:
  explicit TurnRefreshRequest(TurnPort* port);
  virtual void Prepare(StunMessage* request);
  virtual void OnResponse(StunMessage* response);
  virtual void OnErrorResponse(StunMessage* response);
  virtual void OnTimeout();

 private:
  TurnPort* port_;
};

class TurnCreatePermissionRequest : public StunRequest,
                                    public sigslot::has_slots<> {
 public:
  TurnCreatePermissionRequest(TurnPort* port, TurnEntry* entry,
                              const talk_base::SocketAddress& ext_addr);
  virtual void Prepare(StunMessage* request);
  virtual void OnResponse(StunMessage* response);
  virtual void OnErrorResponse(StunMessage* response);
  virtual void OnTimeout();

 private:
  void OnEntryDestroyed(TurnEntry* entry);

  TurnPort* port_;
  TurnEntry* entry_;
  talk_base::SocketAddress ext_addr_;
};

class TurnChannelBindRequest : public StunRequest,
                               public sigslot::has_slots<> {
 public:
  TurnChannelBindRequest(TurnPort* port, TurnEntry* entry, int channel_id,
                         const talk_base::SocketAddress& ext_addr);
  virtual void Prepare(StunMessage* request);
  virtual void OnResponse(StunMessage* response);
  virtual void OnErrorResponse(StunMessage* response);
  virtual void OnTimeout();

 private:
  void OnEntryDestroyed(TurnEntry* entry);

  TurnPort* port_;
  TurnEntry* entry_;
  int channel_id_;
  talk_base::SocketAddress ext_addr_;
};

// Manages a "connection" to a remote destination. We will attempt to bring up
// a channel for this remote destination to reduce the overhead of sending data.
class TurnEntry : public sigslot::has_slots<> {
 public:
  enum BindState { STATE_UNBOUND, STATE_BINDING, STATE_BOUND };
  TurnEntry(TurnPort* port, int channel_id,
            const talk_base::SocketAddress& ext_addr);

  TurnPort* port() { return port_; }

  int channel_id() const { return channel_id_; }
  const talk_base::SocketAddress& address() const { return ext_addr_; }
  BindState state() const { return state_; }

  // Helper methods to send permission and channel bind requests.
  void SendCreatePermissionRequest();
  void SendChannelBindRequest(int delay);
  // Sends a packet to the given destination address.
  // This will wrap the packet in STUN if necessary.
  int Send(const void* data, size_t size, bool payload,
           talk_base::DiffServCodePoint dscp);

  void OnCreatePermissionSuccess();
  void OnCreatePermissionError(StunMessage* response, int code);
  void OnChannelBindSuccess();
  void OnChannelBindError(StunMessage* response, int code);
  // Signal sent when TurnEntry is destroyed.
  sigslot::signal1<TurnEntry*> SignalDestroyed;

 private:
  TurnPort* port_;
  int channel_id_;
  talk_base::SocketAddress ext_addr_;
  BindState state_;
};

TurnPort::TurnPort(talk_base::Thread* thread,
                   talk_base::PacketSocketFactory* factory,
                   talk_base::Network* network,
                   const talk_base::IPAddress& ip,
                   int min_port, int max_port,
                   const std::string& username,
                   const std::string& password,
                   const ProtocolAddress& server_address,
                   const RelayCredentials& credentials)
    : Port(thread, RELAY_PORT_TYPE, factory, network, ip, min_port, max_port,
           username, password),
      server_address_(server_address),
      credentials_(credentials),
      resolver_(NULL),
      error_(0),
      request_manager_(thread),
      next_channel_number_(TURN_CHANNEL_NUMBER_START),
      connected_(false) {
  request_manager_.SignalSendPacket.connect(this, &TurnPort::OnSendStunPacket);
}

TurnPort::~TurnPort() {
  // TODO(juberti): Should this even be necessary?
  while (!entries_.empty()) {
    DestroyEntry(entries_.front()->address());
  }
}

void TurnPort::PrepareAddress() {
  if (credentials_.username.empty() ||
      credentials_.password.empty()) {
    LOG(LS_ERROR) << "Allocation can't be started without setting the"
                  << " TURN server credentials for the user.";
    OnAllocateError();
    return;
  }

  // If protocol family of server address doesn't match with local, return.
  if (!IsCompatibleAddress(server_address_.address)) {
    LOG(LS_ERROR) << "Server IP address family does not match with "
                  << "local host address family type";
    OnAllocateError();
    return;
  }

  if (!server_address_.address.port()) {
    // We will set default TURN port, if no port is set in the address.
    server_address_.address.SetPort(TURN_DEFAULT_PORT);
  }

  if (server_address_.address.IsUnresolved()) {
    ResolveTurnAddress(server_address_.address);
  } else {
    LOG_J(LS_INFO, this) << "Trying to connect to TURN server via "
                         << ProtoToString(server_address_.proto) << " @ "
                         << server_address_.address.ToSensitiveString();
    if (server_address_.proto == PROTO_UDP) {
      socket_.reset(socket_factory()->CreateUdpSocket(
          talk_base::SocketAddress(ip(), 0), min_port(), max_port()));
    } else if (server_address_.proto == PROTO_TCP) {
      int opts = talk_base::PacketSocketFactory::OPT_STUN;
      // If secure bit is enabled in server address, use TLS over TCP.
      if (server_address_.secure) {
        opts |= talk_base::PacketSocketFactory::OPT_TLS;
      }

      socket_.reset(socket_factory()->CreateClientTcpSocket(
          talk_base::SocketAddress(ip(), 0), server_address_.address,
          proxy(), user_agent(), opts));
    }

    if (!socket_) {
      OnAllocateError();
      return;
    }

    // Apply options if any.
    for (SocketOptionsMap::iterator iter = socket_options_.begin();
         iter != socket_options_.end(); ++iter) {
      socket_->SetOption(iter->first, iter->second);
    }

    socket_->SignalReadPacket.connect(this, &TurnPort::OnReadPacket);
    socket_->SignalReadyToSend.connect(this, &TurnPort::OnReadyToSend);

    if (server_address_.proto == PROTO_TCP) {
      socket_->SignalConnect.connect(this, &TurnPort::OnSocketConnect);
      socket_->SignalClose.connect(this, &TurnPort::OnSocketClose);
    } else {
      // If its UDP, send AllocateRequest now.
      // For TCP and TLS AllcateRequest will be sent by OnSocketConnect.
      SendRequest(new TurnAllocateRequest(this), 0);
    }
  }
}

void TurnPort::OnSocketConnect(talk_base::AsyncPacketSocket* socket) {
  LOG(LS_INFO) << "TurnPort connected to " << socket->GetRemoteAddress()
               << " using tcp.";
  SendRequest(new TurnAllocateRequest(this), 0);
}

void TurnPort::OnSocketClose(talk_base::AsyncPacketSocket* socket, int error) {
  LOG_J(LS_WARNING, this) << "Connection with server failed, error=" << error;
  if (!connected_) {
    OnAllocateError();
  }
}

Connection* TurnPort::CreateConnection(const Candidate& address,
                                       CandidateOrigin origin) {
  // TURN-UDP can only connect to UDP candidates.
  if (address.protocol() != UDP_PROTOCOL_NAME) {
    return NULL;
  }

  if (!IsCompatibleAddress(address.address())) {
    return NULL;
  }

  // Create an entry, if needed, so we can get our permissions set up correctly.
  CreateEntry(address.address());

  // TODO(juberti): The '0' index will need to change if we start gathering STUN
  // candidates on this port.
  ProxyConnection* conn = new ProxyConnection(this, 0, address);
  conn->SignalDestroyed.connect(this, &TurnPort::OnConnectionDestroyed);
  AddConnection(conn);
  return conn;
}

int TurnPort::SetOption(talk_base::Socket::Option opt, int value) {
  // DSCP option is not passed to the socket.
  // TODO(mallinath) - After we have the support on socket,
  // remove this specialization.
  if (opt == talk_base::Socket::OPT_DSCP) {
    SetDefaultDscpValue(static_cast<talk_base::DiffServCodePoint>(value));
    return 0;
  }

  if (!socket_) {
    // If socket is not created yet, these options will be applied during socket
    // creation.
    socket_options_[opt] = value;
    return 0;
  }
  return socket_->SetOption(opt, value);
}

int TurnPort::GetOption(talk_base::Socket::Option opt, int* value) {
  if (!socket_)
    return -1;

  return socket_->GetOption(opt, value);
}

int TurnPort::GetError() {
  return error_;
}

int TurnPort::SendTo(const void* data, size_t size,
                     const talk_base::SocketAddress& addr,
                     talk_base::DiffServCodePoint dscp,
                     bool payload) {
  // Try to find an entry for this specific address; we should have one.
  TurnEntry* entry = FindEntry(addr);
  ASSERT(entry != NULL);
  if (!entry) {
    return 0;
  }

  if (!connected()) {
    error_ = EWOULDBLOCK;
    return SOCKET_ERROR;
  }

  // Send the actual contents to the server using the usual mechanism.
  int sent = entry->Send(data, size, payload, dscp);
  if (sent <= 0) {
    return SOCKET_ERROR;
  }

  // The caller of the function is expecting the number of user data bytes,
  // rather than the size of the packet.
  return static_cast<int>(size);
}

void TurnPort::OnReadPacket(talk_base::AsyncPacketSocket* socket,
                           const char* data, size_t size,
                           const talk_base::SocketAddress& remote_addr) {
  ASSERT(socket == socket_.get());
  ASSERT(remote_addr == server_address_.address);

  // The message must be at least the size of a channel header.
  if (size < TURN_CHANNEL_HEADER_SIZE) {
    LOG_J(LS_WARNING, this) << "Received TURN message that was too short";
    return;
  }

  // Check the message type, to see if is a Channel Data message.
  // The message will either be channel data, a TURN data indication, or
  // a response to a previous request.
  uint16 msg_type = talk_base::GetBE16(data);
  if (IsTurnChannelData(msg_type)) {
    HandleChannelData(msg_type, data, size);
  } else if (msg_type == TURN_DATA_INDICATION) {
    HandleDataIndication(data, size);
  } else {
    // This must be a response for one of our requests.
    // Check success responses, but not errors, for MESSAGE-INTEGRITY.
    if (IsStunSuccessResponseType(msg_type) &&
        !StunMessage::ValidateMessageIntegrity(data, size, hash())) {
      LOG_J(LS_WARNING, this) << "Received TURN message with invalid "
                              << "message integrity, msg_type=" << msg_type;
      return;
    }
    request_manager_.CheckResponse(data, size);
  }
}

void TurnPort::OnReadyToSend(talk_base::AsyncPacketSocket* socket) {
  if (connected_) {
    Port::OnReadyToSend();
  }
}

void TurnPort::ResolveTurnAddress(const talk_base::SocketAddress& address) {
  if (resolver_)
    return;

  resolver_ = new talk_base::AsyncResolver();
  resolver_->SignalWorkDone.connect(this, &TurnPort::OnResolveResult);
  resolver_->set_address(address);
  resolver_->Start();
}

void TurnPort::OnResolveResult(talk_base::SignalThread* signal_thread) {
  ASSERT(signal_thread == resolver_);
  if (resolver_->error() != 0) {
    LOG_J(LS_WARNING, this) << "TURN host lookup received error "
                            << resolver_->error();
    OnAllocateError();
    return;
  }

  server_address_.address = resolver_->address();
  PrepareAddress();
}

void TurnPort::OnSendStunPacket(const void* data, size_t size,
                                StunRequest* request) {
  if (Send(data, size, DefaultDscpValue()) < 0) {
    LOG_J(LS_ERROR, this) << "Failed to send TURN message, err="
                          << socket_->GetError();
  }
}

void TurnPort::OnStunAddress(const talk_base::SocketAddress& address) {
  // For relay, mapped address is rel-addr.
  set_related_address(address);
}

void TurnPort::OnAllocateSuccess(const talk_base::SocketAddress& address) {
  connected_ = true;
  AddAddress(address,
             socket_->GetLocalAddress(),
             "udp",
             RELAY_PORT_TYPE,
             GetRelayPreference(server_address_.proto, server_address_.secure),
             true);
}

void TurnPort::OnAllocateError() {
  // We will send SignalPortError asynchronously as this can be sent during
  // port initialization. This way it will not be blocking other port
  // creation.
  thread()->Post(this, MSG_ERROR);
}

void TurnPort::OnMessage(talk_base::Message* message) {
  if (message->message_id == MSG_ERROR) {
    SignalPortError(this);
    return;
  }

  Port::OnMessage(message);
}

void TurnPort::OnAllocateRequestTimeout() {
  OnAllocateError();
}

void TurnPort::HandleDataIndication(const char* data, size_t size) {
  // Read in the message, and process according to RFC5766, Section 10.4.
  talk_base::ByteBuffer buf(data, size);
  TurnMessage msg;
  if (!msg.Read(&buf)) {
    LOG_J(LS_WARNING, this) << "Received invalid TURN data indication";
    return;
  }

  // Check mandatory attributes.
  const StunAddressAttribute* addr_attr =
      msg.GetAddress(STUN_ATTR_XOR_PEER_ADDRESS);
  if (!addr_attr) {
    LOG_J(LS_WARNING, this) << "Missing STUN_ATTR_XOR_PEER_ADDRESS attribute "
                            << "in data indication.";
    return;
  }

  const StunByteStringAttribute* data_attr =
      msg.GetByteString(STUN_ATTR_DATA);
  if (!data_attr) {
    LOG_J(LS_WARNING, this) << "Missing STUN_ATTR_DATA attribute in "
                            << "data indication.";
    return;
  }

  // Verify that the data came from somewhere we think we have a permission for.
  talk_base::SocketAddress ext_addr(addr_attr->GetAddress());
  if (!HasPermission(ext_addr.ipaddr())) {
    LOG_J(LS_WARNING, this) << "Received TURN data indication with invalid "
                            << "peer address, addr="
                            << ext_addr.ToSensitiveString();
    return;
  }

  DispatchPacket(data_attr->bytes(), data_attr->length(), ext_addr, PROTO_UDP);
}

void TurnPort::HandleChannelData(int channel_id, const char* data,
                                 size_t size) {
  // Read the message, and process according to RFC5766, Section 11.6.
  //    0                   1                   2                   3
  //    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
  //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  //   |         Channel Number        |            Length             |
  //   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  //   |                                                               |
  //   /                       Application Data                        /
  //   /                                                               /
  //   |                                                               |
  //   |                               +-------------------------------+
  //   |                               |
  //   +-------------------------------+

  // Extract header fields from the message.
  uint16 len = talk_base::GetBE16(data + 2);
  if (len > size - TURN_CHANNEL_HEADER_SIZE) {
    LOG_J(LS_WARNING, this) << "Received TURN channel data message with "
                            << "incorrect length, len=" << len;
    return;
  }
  // Allowing messages larger than |len|, as ChannelData can be padded.

  TurnEntry* entry = FindEntry(channel_id);
  if (!entry) {
    LOG_J(LS_WARNING, this) << "Received TURN channel data message for invalid "
                            << "channel, channel_id=" << channel_id;
    return;
  }

  DispatchPacket(data + TURN_CHANNEL_HEADER_SIZE, len, entry->address(),
                 PROTO_UDP);
}

void TurnPort::DispatchPacket(const char* data, size_t size,
    const talk_base::SocketAddress& remote_addr, ProtocolType proto) {
  if (Connection* conn = GetConnection(remote_addr)) {
    conn->OnReadPacket(data, size);
  } else {
    Port::OnReadPacket(data, size, remote_addr, proto);
  }
}

bool TurnPort::ScheduleRefresh(int lifetime) {
  // Lifetime is in seconds; we schedule a refresh for one minute less.
  if (lifetime < 2 * 60) {
    LOG_J(LS_WARNING, this) << "Received response with lifetime that was "
                            << "too short, lifetime=" << lifetime;
    return false;
  }

  SendRequest(new TurnRefreshRequest(this), (lifetime - 60) * 1000);
  return true;
}

void TurnPort::SendRequest(StunRequest* req, int delay) {
  request_manager_.SendDelayed(req, delay);
}

void TurnPort::AddRequestAuthInfo(StunMessage* msg) {
  // If we've gotten the necessary data from the server, add it to our request.
  VERIFY(!hash_.empty());
  VERIFY(msg->AddAttribute(new StunByteStringAttribute(
      STUN_ATTR_USERNAME, credentials_.username)));
  VERIFY(msg->AddAttribute(new StunByteStringAttribute(
      STUN_ATTR_REALM, realm_)));
  VERIFY(msg->AddAttribute(new StunByteStringAttribute(
      STUN_ATTR_NONCE, nonce_)));
  VERIFY(msg->AddMessageIntegrity(hash()));
}

int TurnPort::Send(const void* data, size_t len,
                   talk_base::DiffServCodePoint dscp) {
  return socket_->SendTo(data, len, server_address_.address, dscp);
}

void TurnPort::UpdateHash() {
  VERIFY(ComputeStunCredentialHash(credentials_.username, realm_,
                                   credentials_.password, &hash_));
}

bool TurnPort::UpdateNonce(StunMessage* response) {
  // When stale nonce error received, we should update
  // hash and store realm and nonce.
  // Check the mandatory attributes.
  const StunByteStringAttribute* realm_attr =
      response->GetByteString(STUN_ATTR_REALM);
  if (!realm_attr) {
    LOG(LS_ERROR) << "Missing STUN_ATTR_REALM attribute in "
                  << "stale nonce error response.";
    return false;
  }
  set_realm(realm_attr->GetString());

  const StunByteStringAttribute* nonce_attr =
      response->GetByteString(STUN_ATTR_NONCE);
  if (!nonce_attr) {
    LOG(LS_ERROR) << "Missing STUN_ATTR_NONCE attribute in "
                  << "stale nonce error response.";
    return false;
  }
  set_nonce(nonce_attr->GetString());
  return true;
}

static bool MatchesIP(TurnEntry* e, talk_base::IPAddress ipaddr) {
  return e->address().ipaddr() == ipaddr;
}
bool TurnPort::HasPermission(const talk_base::IPAddress& ipaddr) const {
  return (std::find_if(entries_.begin(), entries_.end(),
      std::bind2nd(std::ptr_fun(MatchesIP), ipaddr)) != entries_.end());
}

static bool MatchesAddress(TurnEntry* e, talk_base::SocketAddress addr) {
  return e->address() == addr;
}
TurnEntry* TurnPort::FindEntry(const talk_base::SocketAddress& addr) const {
  EntryList::const_iterator it = std::find_if(entries_.begin(), entries_.end(),
      std::bind2nd(std::ptr_fun(MatchesAddress), addr));
  return (it != entries_.end()) ? *it : NULL;
}

static bool MatchesChannelId(TurnEntry* e, int id) {
  return e->channel_id() == id;
}
TurnEntry* TurnPort::FindEntry(int channel_id) const {
  EntryList::const_iterator it = std::find_if(entries_.begin(), entries_.end(),
      std::bind2nd(std::ptr_fun(MatchesChannelId), channel_id));
  return (it != entries_.end()) ? *it : NULL;
}

TurnEntry* TurnPort::CreateEntry(const talk_base::SocketAddress& addr) {
  ASSERT(FindEntry(addr) == NULL);
  TurnEntry* entry = new TurnEntry(this, next_channel_number_++, addr);
  entries_.push_back(entry);
  return entry;
}

void TurnPort::DestroyEntry(const talk_base::SocketAddress& addr) {
  TurnEntry* entry = FindEntry(addr);
  ASSERT(entry != NULL);
  entry->SignalDestroyed(entry);
  entries_.remove(entry);
  delete entry;
}

void TurnPort::OnConnectionDestroyed(Connection* conn) {
  // Destroying TurnEntry for the connection, which is already destroyed.
  DestroyEntry(conn->remote_candidate().address());
}

TurnAllocateRequest::TurnAllocateRequest(TurnPort* port)
    : StunRequest(new TurnMessage()),
      port_(port) {
}

void TurnAllocateRequest::Prepare(StunMessage* request) {
  // Create the request as indicated in RFC 5766, Section 6.1.
  request->SetType(TURN_ALLOCATE_REQUEST);
  StunUInt32Attribute* transport_attr = StunAttribute::CreateUInt32(
      STUN_ATTR_REQUESTED_TRANSPORT);
  transport_attr->SetValue(IPPROTO_UDP << 24);
  VERIFY(request->AddAttribute(transport_attr));
  if (!port_->hash().empty()) {
    port_->AddRequestAuthInfo(request);
  }
}

void TurnAllocateRequest::OnResponse(StunMessage* response) {
  // Check mandatory attributes as indicated in RFC5766, Section 6.3.
  const StunAddressAttribute* mapped_attr =
      response->GetAddress(STUN_ATTR_XOR_MAPPED_ADDRESS);
  if (!mapped_attr) {
    LOG_J(LS_WARNING, port_) << "Missing STUN_ATTR_XOR_MAPPED_ADDRESS "
                             << "attribute in allocate success response";
    return;
  }

  // TODO(mallinath) - Use mapped address for STUN candidate.
  port_->OnStunAddress(mapped_attr->GetAddress());

  const StunAddressAttribute* relayed_attr =
      response->GetAddress(STUN_ATTR_XOR_RELAYED_ADDRESS);
  if (!relayed_attr) {
    LOG_J(LS_WARNING, port_) << "Missing STUN_ATTR_XOR_RELAYED_ADDRESS "
                             << "attribute in allocate success response";
    return;
  }

  const StunUInt32Attribute* lifetime_attr =
      response->GetUInt32(STUN_ATTR_TURN_LIFETIME);
  if (!lifetime_attr) {
    LOG_J(LS_WARNING, port_) << "Missing STUN_ATTR_TURN_LIFETIME attribute in "
                             << "allocate success response";
    return;
  }
  // Notify the port the allocate succeeded, and schedule a refresh request.
  port_->OnAllocateSuccess(relayed_attr->GetAddress());
  port_->ScheduleRefresh(lifetime_attr->value());
}

void TurnAllocateRequest::OnErrorResponse(StunMessage* response) {
  // Process error response according to RFC5766, Section 6.4.
  const StunErrorCodeAttribute* error_code = response->GetErrorCode();
  switch (error_code->code()) {
    case STUN_ERROR_UNAUTHORIZED:       // Unauthrorized.
      OnAuthChallenge(response, error_code->code());
      break;
    default:
      LOG_J(LS_WARNING, port_) << "Allocate response error, code="
                               << error_code->code();
      port_->OnAllocateError();
  }
}

void TurnAllocateRequest::OnTimeout() {
  LOG_J(LS_WARNING, port_) << "Allocate request timeout";
  port_->OnAllocateRequestTimeout();
}

void TurnAllocateRequest::OnAuthChallenge(StunMessage* response, int code) {
  // If we failed to authenticate even after we sent our credentials, fail hard.
  if (code == STUN_ERROR_UNAUTHORIZED && !port_->hash().empty()) {
    LOG_J(LS_WARNING, port_) << "Failed to authenticate with the server "
                             << "after challenge.";
    port_->OnAllocateError();
    return;
  }

  // Check the mandatory attributes.
  const StunByteStringAttribute* realm_attr =
      response->GetByteString(STUN_ATTR_REALM);
  if (!realm_attr) {
    LOG_J(LS_WARNING, port_) << "Missing STUN_ATTR_REALM attribute in "
                             << "allocate unauthorized response.";
    return;
  }
  port_->set_realm(realm_attr->GetString());

  const StunByteStringAttribute* nonce_attr =
      response->GetByteString(STUN_ATTR_NONCE);
  if (!nonce_attr) {
    LOG_J(LS_WARNING, port_) << "Missing STUN_ATTR_NONCE attribute in "
                             << "allocate unauthorized response.";
    return;
  }
  port_->set_nonce(nonce_attr->GetString());

  // Send another allocate request, with the received realm and nonce values.
  port_->SendRequest(new TurnAllocateRequest(port_), 0);
}

TurnRefreshRequest::TurnRefreshRequest(TurnPort* port)
    : StunRequest(new TurnMessage()),
      port_(port) {
}

void TurnRefreshRequest::Prepare(StunMessage* request) {
  // Create the request as indicated in RFC 5766, Section 7.1.
  // No attributes need to be included.
  request->SetType(TURN_REFRESH_REQUEST);
  port_->AddRequestAuthInfo(request);
}

void TurnRefreshRequest::OnResponse(StunMessage* response) {
  // Check mandatory attributes as indicated in RFC5766, Section 7.3.
  const StunUInt32Attribute* lifetime_attr =
      response->GetUInt32(STUN_ATTR_TURN_LIFETIME);
  if (!lifetime_attr) {
    LOG_J(LS_WARNING, port_) << "Missing STUN_ATTR_TURN_LIFETIME attribute in "
                             << "refresh success response.";
    return;
  }

  // Schedule a refresh based on the returned lifetime value.
  port_->ScheduleRefresh(lifetime_attr->value());
}

void TurnRefreshRequest::OnErrorResponse(StunMessage* response) {
  // TODO(juberti): Handle 437 error response as a success.
  const StunErrorCodeAttribute* error_code = response->GetErrorCode();
  LOG_J(LS_WARNING, port_) << "Refresh response error, code="
                           << error_code->code();

  if (error_code->code() == STUN_ERROR_STALE_NONCE) {
    if (port_->UpdateNonce(response)) {
      // Send RefreshRequest immediately.
      port_->SendRequest(new TurnRefreshRequest(port_), 0);
    }
  }
}

void TurnRefreshRequest::OnTimeout() {
}

TurnCreatePermissionRequest::TurnCreatePermissionRequest(
    TurnPort* port, TurnEntry* entry,
    const talk_base::SocketAddress& ext_addr)
    : StunRequest(new TurnMessage()),
      port_(port),
      entry_(entry),
      ext_addr_(ext_addr) {
  entry_->SignalDestroyed.connect(
      this, &TurnCreatePermissionRequest::OnEntryDestroyed);
}

void TurnCreatePermissionRequest::Prepare(StunMessage* request) {
  // Create the request as indicated in RFC5766, Section 9.1.
  request->SetType(TURN_CREATE_PERMISSION_REQUEST);
  VERIFY(request->AddAttribute(new StunXorAddressAttribute(
      STUN_ATTR_XOR_PEER_ADDRESS, ext_addr_)));
  port_->AddRequestAuthInfo(request);
}

void TurnCreatePermissionRequest::OnResponse(StunMessage* response) {
  if (entry_) {
    entry_->OnCreatePermissionSuccess();
  }
}

void TurnCreatePermissionRequest::OnErrorResponse(StunMessage* response) {
  if (entry_) {
    const StunErrorCodeAttribute* error_code = response->GetErrorCode();
    entry_->OnCreatePermissionError(response, error_code->code());
  }
}

void TurnCreatePermissionRequest::OnTimeout() {
  LOG_J(LS_WARNING, port_) << "Create permission timeout";
}

void TurnCreatePermissionRequest::OnEntryDestroyed(TurnEntry* entry) {
  ASSERT(entry_ == entry);
  entry_ = NULL;
}

TurnChannelBindRequest::TurnChannelBindRequest(
    TurnPort* port, TurnEntry* entry,
    int channel_id, const talk_base::SocketAddress& ext_addr)
    : StunRequest(new TurnMessage()),
      port_(port),
      entry_(entry),
      channel_id_(channel_id),
      ext_addr_(ext_addr) {
  entry_->SignalDestroyed.connect(
      this, &TurnChannelBindRequest::OnEntryDestroyed);
}

void TurnChannelBindRequest::Prepare(StunMessage* request) {
  // Create the request as indicated in RFC5766, Section 11.1.
  request->SetType(TURN_CHANNEL_BIND_REQUEST);
  VERIFY(request->AddAttribute(new StunUInt32Attribute(
      STUN_ATTR_CHANNEL_NUMBER, channel_id_ << 16)));
  VERIFY(request->AddAttribute(new StunXorAddressAttribute(
      STUN_ATTR_XOR_PEER_ADDRESS, ext_addr_)));
  port_->AddRequestAuthInfo(request);
}

void TurnChannelBindRequest::OnResponse(StunMessage* response) {
  if (entry_) {
    entry_->OnChannelBindSuccess();
    // Refresh the channel binding just under the permission timeout
    // threshold. The channel binding has a longer lifetime, but
    // this is the easiest way to keep both the channel and the
    // permission from expiring.
    entry_->SendChannelBindRequest(TURN_PERMISSION_TIMEOUT - 60 * 1000);
  }
}

void TurnChannelBindRequest::OnErrorResponse(StunMessage* response) {
  if (entry_) {
    const StunErrorCodeAttribute* error_code = response->GetErrorCode();
    entry_->OnChannelBindError(response, error_code->code());
  }
}

void TurnChannelBindRequest::OnTimeout() {
  LOG_J(LS_WARNING, port_) << "Channel bind timeout";
}

void TurnChannelBindRequest::OnEntryDestroyed(TurnEntry* entry) {
  ASSERT(entry_ == entry);
  entry_ = NULL;
}

TurnEntry::TurnEntry(TurnPort* port, int channel_id,
                     const talk_base::SocketAddress& ext_addr)
    : port_(port),
      channel_id_(channel_id),
      ext_addr_(ext_addr),
      state_(STATE_UNBOUND) {
  // Creating permission for |ext_addr_|.
  SendCreatePermissionRequest();
}

void TurnEntry::SendCreatePermissionRequest() {
  port_->SendRequest(new TurnCreatePermissionRequest(
      port_, this, ext_addr_), 0);
}

void TurnEntry::SendChannelBindRequest(int delay) {
  port_->SendRequest(new TurnChannelBindRequest(
      port_, this, channel_id_, ext_addr_), delay);
}

int TurnEntry::Send(const void* data, size_t size, bool payload,
                    talk_base::DiffServCodePoint dscp) {
  talk_base::ByteBuffer buf;
  if (state_ != STATE_BOUND) {
    // If we haven't bound the channel yet, we have to use a Send Indication.
    TurnMessage msg;
    msg.SetType(TURN_SEND_INDICATION);
    msg.SetTransactionID(
        talk_base::CreateRandomString(kStunTransactionIdLength));
    VERIFY(msg.AddAttribute(new StunXorAddressAttribute(
        STUN_ATTR_XOR_PEER_ADDRESS, ext_addr_)));
    VERIFY(msg.AddAttribute(new StunByteStringAttribute(
        STUN_ATTR_DATA, data, size)));
    VERIFY(msg.Write(&buf));

    // If we're sending real data, request a channel bind that we can use later.
    if (state_ == STATE_UNBOUND && payload) {
      SendChannelBindRequest(0);
      state_ = STATE_BINDING;
    }
  } else {
    // If the channel is bound, we can send the data as a Channel Message.
    buf.WriteUInt16(channel_id_);
    buf.WriteUInt16(static_cast<uint16>(size));
    buf.WriteBytes(reinterpret_cast<const char*>(data), size);
  }
  return port_->Send(buf.Data(), buf.Length(), dscp);
}

void TurnEntry::OnCreatePermissionSuccess() {
  LOG_J(LS_INFO, port_) << "Create permission for "
                        << ext_addr_.ToSensitiveString()
                        << " succeeded";
  // For success result code will be 0.
  port_->SignalCreatePermissionResult(port_, ext_addr_, 0);
}

void TurnEntry::OnCreatePermissionError(StunMessage* response, int code) {
  LOG_J(LS_WARNING, port_) << "Create permission for "
                           << ext_addr_.ToSensitiveString()
                           << " failed, code=" << code;
  if (code == STUN_ERROR_STALE_NONCE) {
    if (port_->UpdateNonce(response)) {
      SendCreatePermissionRequest();
    }
  } else {
    // Send signal with error code.
    port_->SignalCreatePermissionResult(port_, ext_addr_, code);
  }
}

void TurnEntry::OnChannelBindSuccess() {
  LOG_J(LS_INFO, port_) << "Channel bind for " << ext_addr_.ToSensitiveString()
                        << " succeeded";
  ASSERT(state_ == STATE_BINDING || state_ == STATE_BOUND);
  state_ = STATE_BOUND;
}

void TurnEntry::OnChannelBindError(StunMessage* response, int code) {
  // TODO(mallinath) - Implement handling of error response for channel
  // bind request as per http://tools.ietf.org/html/rfc5766#section-11.3
  LOG_J(LS_WARNING, port_) << "Channel bind for "
                           << ext_addr_.ToSensitiveString()
                           << " failed, code=" << code;
  if (code == STUN_ERROR_STALE_NONCE) {
    if (port_->UpdateNonce(response)) {
      // Send channel bind request with fresh nonce.
      SendChannelBindRequest(0);
    }
  }
}

}  // namespace cricket