problem: ws_engine duplicate code from stream_engine

Solution: New class called stream_engine_base which is inherited by ws_engine, zmtp_engine and raw_engine.

src/zmtp_engine.hpp

@@ -0,0 +1,133 @@
+/*
+    Copyright (c) 2007-2019 Contributors as noted in the AUTHORS file
+
+    This file is part of libzmq, the ZeroMQ core engine in C++.
+
+    libzmq is free software; you can redistribute it and/or modify it under
+    the terms of the GNU Lesser General Public License (LGPL) as published
+    by the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.
+
+    As a special exception, the Contributors give you permission to link
+    this library with independent modules to produce an executable,
+    regardless of the license terms of these independent modules, and to
+    copy and distribute the resulting executable under terms of your choice,
+    provided that you also meet, for each linked independent module, the
+    terms and conditions of the license of that module. An independent
+    module is a module which is not derived from or based on this library.
+    If you modify this library, you must extend this exception to your
+    version of the library.
+
+    libzmq is distributed in the hope that it will be useful, but WITHOUT
+    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+    FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
+    License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef __ZMQ_ZMTP_ENGINE_HPP_INCLUDED__
+#define __ZMQ_ZMTP_ENGINE_HPP_INCLUDED__
+
+#include <stddef.h>
+
+#include "fd.hpp"
+#include "i_engine.hpp"
+#include "io_object.hpp"
+#include "i_encoder.hpp"
+#include "i_decoder.hpp"
+#include "options.hpp"
+#include "socket_base.hpp"
+#include "metadata.hpp"
+#include "msg.hpp"
+#include "stream_engine_base.hpp"
+
+namespace zmq
+{
+//  Protocol revisions
+enum
+{
+    ZMTP_1_0 = 0,
+    ZMTP_2_0 = 1
+};
+
+class io_thread_t;
+class session_base_t;
+class mechanism_t;
+
+//  This engine handles any socket with SOCK_STREAM semantics,
+//  e.g. TCP socket or an UNIX domain socket.
+
+class zmtp_engine_t : public stream_engine_base_t
+{
+  public:
+    zmtp_engine_t (fd_t fd_,
+                   const options_t &options_,
+                   const endpoint_uri_pair_t &endpoint_uri_pair_);
+    ~zmtp_engine_t ();
+
+  protected:
+    //  Detects the protocol used by the peer.
+    bool handshake ();
+
+    void plug_internal ();
+
+    int process_command_message (msg_t *msg_);
+    int produce_ping_message (msg_t *msg_);
+    int process_heartbeat_message (msg_t *msg_);
+    int produce_pong_message (msg_t *msg_);
+
+  private:
+    //  Receive the greeting from the peer.
+    int receive_greeting ();
+    void receive_greeting_versioned ();
+
+    typedef bool (zmtp_engine_t::*handshake_fun_t) ();
+    static handshake_fun_t select_handshake_fun (bool unversioned,
+                                                 unsigned char revision);
+
+    bool handshake_v1_0_unversioned ();
+    bool handshake_v1_0 ();
+    bool handshake_v2_0 ();
+    bool handshake_v3_0 ();
+
+    int routing_id_msg (msg_t *msg_);
+    int process_routing_id_msg (msg_t *msg_);
+
+    msg_t _routing_id_msg;
+
+    //  Need to store PING payload for PONG
+    msg_t _pong_msg;
+
+    static const size_t signature_size = 10;
+
+    //  Size of ZMTP/1.0 and ZMTP/2.0 greeting message
+    static const size_t v2_greeting_size = 12;
+
+    //  Size of ZMTP/3.0 greeting message
+    static const size_t v3_greeting_size = 64;
+
+    //  Expected greeting size.
+    size_t _greeting_size;
+
+    //  Greeting received from, and sent to peer
+    unsigned char _greeting_recv[v3_greeting_size];
+    unsigned char _greeting_send[v3_greeting_size];
+
+    //  Size of greeting received so far
+    unsigned int _greeting_bytes_read;
+
+    //  Indicates whether the engine is to inject a phantom
+    //  subscription message into the incoming stream.
+    //  Needed to support old peers.
+    bool _subscription_required;
+
+    int _heartbeat_timeout;
+
+    zmtp_engine_t (const zmtp_engine_t &);
+    const zmtp_engine_t &operator= (const zmtp_engine_t &);
+};
+}
+
+#endif