Merge pull request #554 from hurtonm/master

Implement ZMTP/3.0 PLAIN mechanism

src/Makefile.am

@@ -39,9 +39,11 @@ libzmq_la_SOURCES = \
     lb.hpp \
     likely.hpp \
     mailbox.hpp \
+    mechanism.hpp  \
     msg.hpp \
     mtrie.hpp \
     mutex.hpp \
+    null_mechanism.hpp \
     object.hpp \
     options.hpp \
     own.hpp \
@@ -49,6 +51,7 @@ libzmq_la_SOURCES = \
     pgm_sender.hpp \
     pgm_socket.hpp \
     pipe.hpp \
+    plain_mechanism.hpp \
     platform.hpp \
     poll.hpp \
     poller.hpp \
@@ -100,8 +103,10 @@ libzmq_la_SOURCES = \
     kqueue.cpp \
     lb.cpp \
     mailbox.cpp \
+    mechanism.cpp \
     msg.cpp \
     mtrie.cpp \
+    null_mechanism.cpp \
     object.cpp \
     options.cpp \
     own.cpp \
@@ -110,6 +115,7 @@ libzmq_la_SOURCES = \
     pgm_sender.cpp \
     pgm_socket.cpp \
     pipe.cpp \
+    plain_mechanism.cpp \
     poll.cpp \
     poller_base.cpp \
     pull.cpp \

src/ipc_connecter.cpp

@@ -112,7 +112,8 @@ void zmq::ipc_connecter_t::out_event ()
         return;
     }
     //  Create the engine object for this connection.
-    stream_engine_t *engine = new (std::nothrow) stream_engine_t (fd, options, endpoint);
+    stream_engine_t *engine = new (std::nothrow)
+        stream_engine_t (fd, options, false, endpoint);
     alloc_assert (engine);
 
     //  Attach the engine to the corresponding session object.

src/ipc_listener.cpp

@@ -80,7 +80,8 @@ void zmq::ipc_listener_t::in_event ()
     }
 
     //  Create the engine object for this connection.
-    stream_engine_t *engine = new (std::nothrow) stream_engine_t (fd, options, endpoint);
+    stream_engine_t *engine = new (std::nothrow)
+        stream_engine_t (fd, options, true, endpoint);
     alloc_assert (engine);
 
     //  Choose I/O thread to run connecter in. Given that we are already

src/mechanism.cpp

+/*
+    Copyright (c) 2007-2013 Contributors as noted in the AUTHORS file
+
+    This file is part of 0MQ.
+
+    0MQ is free software; you can redistribute it and/or modify it under
+    the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.
+
+    0MQ 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/>.
+*/
+
+#include <string.h>
+
+#include "mechanism.hpp"
+#include "options.hpp"
+#include "msg.hpp"
+#include "err.hpp"
+#include "wire.hpp"
+
+zmq::mechanism_t::mechanism_t (const options_t &options_) :
+    options (options_)
+{
+}
+
+zmq::mechanism_t::~mechanism_t ()
+{
+}
+
+void zmq::mechanism_t::set_peer_identity (const void *id_ptr, size_t id_size)
+{
+    identity = blob_t (static_cast <const unsigned char*> (id_ptr), id_size);
+}
+
+void zmq::mechanism_t::peer_identity (msg_t *msg_)
+{
+    const int rc = msg_->init_size (identity.size ());
+    errno_assert (rc == 0);
+    memcpy (msg_->data (), identity.data (), identity.size ());
+    msg_->set_flags (msg_t::identity);
+}
+
+const char *zmq::mechanism_t::socket_type_string (int socket_type) const
+{
+    static const char *names [] = {"PAIR", "PUB", "SUB", "REQ", "REP",
+                                   "DEALER", "ROUTER", "PULL", "PUSH",
+                                   "XPUB", "XSUB"};
+    zmq_assert (socket_type >= 0 && socket_type <= 10);
+    return names [socket_type];
+}
+
+size_t zmq::mechanism_t::add_property (unsigned char *ptr, const char *name,
+    const void *value, size_t value_len) const
+{
+    const size_t name_len = strlen (name);
+    zmq_assert (name_len <= 255);
+    *ptr++ = static_cast <unsigned char> (name_len);
+    memcpy (ptr, name, name_len);
+    ptr += name_len;
+    zmq_assert (value_len <= (2^31) - 1);
+    put_uint32 (ptr, static_cast <uint32_t> (value_len));
+    ptr += 4;
+    memcpy (ptr, value, value_len);
+
+    return 1 + name_len + 4 + value_len;
+}

src/mechanism.hpp

+/*
+    Copyright (c) 2007-2013 Contributors as noted in the AUTHORS file
+
+    This file is part of 0MQ.
+
+    0MQ is free software; you can redistribute it and/or modify it under
+    the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.
+
+    0MQ 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_MECHANISM_HPP_INCLUDED__
+#define __ZMQ_MECHANISM_HPP_INCLUDED__
+
+#include <stdint.h>
+
+#include "options.hpp"
+#include "blob.hpp"
+
+namespace zmq
+{
+
+    //  Abstract class representing security mechanism.
+    //  Different mechanism extedns this class.
+
+    class msg_t;
+
+    class mechanism_t
+    {
+    public:
+
+        mechanism_t (const options_t &options_);
+
+        virtual ~mechanism_t ();
+
+        //  Prepare next handshake message that is to be sent to the peer.
+        virtual int next_handshake_message (msg_t *msg_) = 0;
+
+        //  Process the handshake message received from the peer.
+        virtual int process_handshake_message (msg_t *msg_) = 0;
+
+        //  True iff the handshake stage is complete?
+        virtual bool is_handshake_complete () const = 0;
+
+        void set_peer_identity (const void *id_ptr, size_t id_size);
+
+        void peer_identity (msg_t *msg_);
+
+    protected:
+
+        const char *socket_type_string (int socket_type) const;
+
+        size_t add_property (unsigned char *ptr, const char *name,
+            const void *value, size_t value_len) const;
+
+        options_t options;
+
+    private:
+
+        blob_t identity;
+    };
+
+}
+
+#endif

src/null_mechanism.cpp

+/*
+    Copyright (c) 2007-2013 Contributors as noted in the AUTHORS file
+
+    This file is part of 0MQ.
+
+    0MQ is free software; you can redistribute it and/or modify it under
+    the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.
+
+    0MQ 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/>.
+*/
+
+#include "platform.hpp"
+#ifdef ZMQ_HAVE_WINDOWS
+#include "windows.hpp"
+#endif
+
+#include <stddef.h>
+#include <string.h>
+#include <stdlib.h>
+
+#include "err.hpp"
+#include "msg.hpp"
+#include "wire.hpp"
+#include "null_mechanism.hpp"
+
+zmq::null_mechanism_t::null_mechanism_t (const options_t &options_) : mechanism_t (options_),
+  ready_command_sent (false),
+  ready_command_received (false)
+{
+}
+
+zmq::null_mechanism_t::~null_mechanism_t ()
+{
+}
+
+int zmq::null_mechanism_t::next_handshake_message (msg_t *msg_)
+{
+    if (ready_command_sent) {
+        errno = EAGAIN;
+        return -1;
+    }
+
+    unsigned char * const command_buffer = (unsigned char *) malloc (512);
+    alloc_assert (command_buffer);
+
+    unsigned char *ptr = command_buffer;
+
+    //  Add mechanism string
+    memcpy (ptr, "READY   ", 8);
+    ptr += 8;
+
+    //  Add socket type property
+    const char *socket_type = socket_type_string (options.type);
+    ptr += add_property (ptr, "Socket-Type", socket_type, strlen (socket_type));
+
+    //  Add identity property
+    if (options.type == ZMQ_REQ
+    ||  options.type == ZMQ_DEALER
+    ||  options.type == ZMQ_ROUTER) {
+        ptr += add_property (ptr, "Identity",
+            options.identity, options.identity_size);
+    }
+
+    const size_t command_size = ptr - command_buffer;
+    const int rc = msg_->init_size (command_size);
+    errno_assert (rc == 0);
+    memcpy (msg_->data (), command_buffer, command_size);
+    free (command_buffer);
+
+    ready_command_sent = true;
+
+    return 0;
+}
+
+int zmq::null_mechanism_t::process_handshake_message (msg_t *msg_)
+{
+    if (ready_command_received) {
+        errno = EPROTO;
+        return -1;
+    }
+
+    const unsigned char *ptr =
+        static_cast <unsigned char *> (msg_->data ());
+    size_t bytes_left = msg_->size ();
+
+    if (bytes_left < 8 || memcmp (ptr, "READY   ", 8)) {
+        errno = EPROTO;
+        return -1;
+    }
+
+    ptr += 8;
+    bytes_left -= 8;
+
+    //  Parse the property list
+    while (bytes_left > 1) {
+        const size_t name_length = static_cast <size_t> (*ptr);
+        ptr += 1;
+        bytes_left -= 1;
+
+        if (bytes_left < name_length)
+            break;
+        const std::string name = std::string((const char *) ptr, name_length);
+        ptr += name_length;
+        bytes_left -= name_length;
+
+        if (bytes_left < 4)
+            break;
+        const size_t value_length = static_cast <size_t> (get_uint32 (ptr));
+        ptr += 4;
+        bytes_left -= 4;
+
+        if (bytes_left < value_length)
+            break;
+        const unsigned char * const value = ptr;
+        ptr += value_length;
+        bytes_left -= value_length;
+
+        if (name == "Socket-Type") {
+            //  TODO: Implement socket type checking
+        }
+        else
+        if (name == "Identity" && options.recv_identity)
+            set_peer_identity (value, value_length);
+    }
+
+    if (bytes_left > 0) {
+        errno = EPROTO;
+        return -1;
+    }
+
+    int rc = msg_->close ();
+    errno_assert (rc == 0);
+    rc = msg_->init ();
+    errno_assert (rc == 0);
+
+    ready_command_received = true;
+
+    return 0;
+}
+
+bool zmq::null_mechanism_t::is_handshake_complete () const
+{
+    return ready_command_received && ready_command_sent;
+}

src/null_mechanism.hpp

+/*
+    Copyright (c) 2007-2013 Contributors as noted in the AUTHORS file
+
+    This file is part of 0MQ.
+
+    0MQ is free software; you can redistribute it and/or modify it under
+    the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.
+
+    0MQ 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_NULL_MECHANISM_HPP_INCLUDED__
+#define __ZMQ_NULL_MECHANISM_HPP_INCLUDED__
+
+#include "mechanism.hpp"
+#include "options.hpp"
+
+namespace zmq
+{
+
+    class msg_t;
+
+    class null_mechanism_t : public mechanism_t
+    {
+    public:
+
+        null_mechanism_t (const options_t &options_);
+        virtual ~null_mechanism_t ();
+
+        // mechanism implementation
+        virtual int next_handshake_message (msg_t *msg_);
+        virtual int process_handshake_message (msg_t *msg_);
+        virtual bool is_handshake_complete () const;
+
+    private:
+
+        bool ready_command_sent;
+        bool ready_command_received;
+    };
+
+}
+
+#endif

src/plain_mechanism.cpp

+/*
+    Copyright (c) 2007-2013 Contributors as noted in the AUTHORS file
+
+    This file is part of 0MQ.
+
+    0MQ is free software; you can redistribute it and/or modify it under
+    the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.
+
+    0MQ 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/>.
+*/
+
+#include "platform.hpp"
+#ifdef ZMQ_HAVE_WINDOWS
+#include "windows.hpp"
+#endif
+
+#include <string.h>
+#include <string>
+
+#include "msg.hpp"
+#include "err.hpp"
+#include "plain_mechanism.hpp"
+#include "wire.hpp"
+
+zmq::plain_mechanism_t::plain_mechanism_t (const options_t &options_,
+                                           bool as_server_) :
+    mechanism_t (options_),
+    state (as_server_? waiting_for_hello: sending_hello)
+{
+}
+
+zmq::plain_mechanism_t::~plain_mechanism_t ()
+{
+}
+
+int zmq::plain_mechanism_t::next_handshake_message (msg_t *msg_)
+{
+    int rc = 0;
+
+    switch (state) {
+    case sending_hello:
+        rc = hello_command (msg_);
+        if (rc == 0)
+            state = waiting_for_welcome;
+        break;
+    case sending_welcome:
+        rc = welcome_command (msg_);
+        if (rc == 0)
+            state = waiting_for_initiate;
+        break;
+    case sending_initiate:
+        rc = initiate_command (msg_);
+        if (rc == 0)
+            state = waiting_for_ready;
+        break;
+    case sending_ready:
+        rc = ready_command (msg_);
+        if (rc == 0)
+            state = ready;
+        break;
+    default:
+        errno = EAGAIN;
+        rc = -1;
+    }
+
+    return rc;
+}
+
+int zmq::plain_mechanism_t::process_handshake_message (msg_t *msg_)
+{
+    int rc = 0;
+
+    switch (state) {
+    case waiting_for_hello:
+        rc = process_hello_command (msg_);
+        if (rc == 0)
+            state = sending_welcome;
+        break;
+    case waiting_for_welcome:
+        rc = process_welcome_command (msg_);
+        if (rc == 0)
+            state = sending_initiate;
+        break;
+    case waiting_for_initiate:
+        rc = process_initiate_command (msg_);
+        if (rc == 0)
+            state = sending_ready;
+        break;
+    case waiting_for_ready:
+        rc = process_ready_command (msg_);
+        if (rc == 0)
+            state = ready;
+        break;
+    default:
+        errno = EAGAIN;
+        rc = -1;
+    }
+
+    if (rc == 0) {
+        rc = msg_->close ();
+        errno_assert (rc == 0);
+        rc = msg_->init ();
+        errno_assert (rc == 0);
+    }
+
+    return 0;
+}
+
+bool zmq::plain_mechanism_t::is_handshake_complete () const
+{
+    return state == ready;
+}
+
+int zmq::plain_mechanism_t::hello_command (msg_t *msg_) const
+{
+    //  TODO: fetch these from options
+    const std::string username = "username";
+    const std::string password = "password";
+
+    zmq_assert (username.length () < 256);
+    zmq_assert (password.length () < 256);
+
+    const size_t command_size = 8 + 1 + username.length () +
+        1 + password.length ();
+
+    const int rc = msg_->init_size (command_size);
+    errno_assert (rc == 0);
+
+    unsigned char *ptr = static_cast<unsigned char*> (msg_->data ());
+
+    memcpy (ptr, "HELLO   ", 8);
+    ptr += 8;
+    *ptr++ = static_cast <unsigned char> (username.length ());
+    memcpy (ptr, username.c_str (), username.length ());
+    ptr += username.length ();
+    *ptr++ = static_cast <unsigned char> (password.length ());
+    memcpy (ptr, password.c_str (), password.length ());
+    ptr += password.length ();
+
+    // TODO: check username and password
+
+    return 0;
+}
+
+int zmq::plain_mechanism_t::process_hello_command (msg_t *msg_)
+{
+    const unsigned char *ptr = static_cast <unsigned char *> (msg_->data ());
+    size_t bytes_left = msg_->size ();
+
+    if (bytes_left < 8 || memcmp (ptr, "HELLO   ", 8)) {
+        errno = EPROTO;
+        return -1;
+    }
+
+    ptr += 8;
+    bytes_left -= 8;
+
+    if (bytes_left < 1) {
+        errno = EPROTO;
+        return -1;
+    }
+
+    size_t username_length = static_cast <size_t> (*ptr++);
+    bytes_left -= 1;
+
+    if (bytes_left < username_length) {
+        errno = EPROTO;
+        return -1;
+    }
+
+    const std::string username = std::string ((char *) ptr, username_length);
+    ptr += username_length;
+    bytes_left -= username_length;
+
+    if (bytes_left < 1) {
+        errno = EPROTO;
+        return -1;
+    }
+
+    size_t password_length = static_cast <size_t> (*ptr++);
+    bytes_left -= 1;
+
+    if (bytes_left < password_length) {
+        errno = EPROTO;
+        return -1;
+    }
+
+    const std::string password = std::string ((char *) ptr, password_length);
+    ptr += password_length;
+    bytes_left -= password_length;
+
+    if (bytes_left > 0) {
+        errno = EPROTO;
+        return -1;
+    }
+
+    return 0;
+}
+
+int zmq::plain_mechanism_t::welcome_command (msg_t *msg_) const
+{
+    const int rc = msg_->init_size (8);
+    errno_assert (rc == 0);
+    memcpy (msg_->data (), "WELCOME ", 8);
+    return 0;
+}
+
+int zmq::plain_mechanism_t::process_welcome_command (msg_t *msg_)
+{
+    const unsigned char *ptr = static_cast <unsigned char *> (msg_->data ());
+    size_t bytes_left = msg_->size ();
+
+    if (bytes_left != 8 ||  memcmp (ptr, "WELCOME ", 8)) {
+        errno = EPROTO;
+        return -1;
+    }
+
+    return 0;
+}
+
+int zmq::plain_mechanism_t::initiate_command (msg_t *msg_) const
+{
+    unsigned char * const command_buffer = (unsigned char *) malloc (512);
+    alloc_assert (command_buffer);
+
+    unsigned char *ptr = command_buffer;
+
+    //  Add mechanism string
+    memcpy (ptr, "INITIATE", 8);
+    ptr += 8;
+
+    //  Add socket type property
+    const char *socket_type = socket_type_string (options.type);
+    ptr += add_property (ptr, "Socket-Type", socket_type, strlen (socket_type));
+
+    //  Add identity property
+    if (options.type == ZMQ_REQ
+    ||  options.type == ZMQ_DEALER
+    ||  options.type == ZMQ_ROUTER) {
+        ptr += add_property (ptr, "Identity",
+            options.identity, options.identity_size);
+    }
+
+    const size_t command_size = ptr - command_buffer;
+    const int rc = msg_->init_size (command_size);
+    errno_assert (rc == 0);
+    memcpy (msg_->data (), command_buffer, command_size);
+    free (command_buffer);
+
+    return 0;
+}
+
+int zmq::plain_mechanism_t::process_initiate_command (msg_t *msg_)
+{
+    const unsigned char *ptr = static_cast <unsigned char *> (msg_->data ());
+    size_t bytes_left = msg_->size ();
+
+    if (bytes_left < 8 || memcmp (ptr, "INITIATE", 8)) {
+        errno = EPROTO;
+        return -1;
+    }
+
+    return parse_property_list (ptr + 8, bytes_left - 8);
+}
+
+int zmq::plain_mechanism_t::ready_command (msg_t *msg_) const
+{
+    unsigned char * const command_buffer = (unsigned char *) malloc (512);
+    alloc_assert (command_buffer);
+
+    unsigned char *ptr = command_buffer;
+
+    //  Add mechanism string
+    memcpy (ptr, "READY   ", 8);
+    ptr += 8;
+
+    //  Add socket type property
+    const char *socket_type = socket_type_string (options.type);
+    ptr += add_property (ptr, "Socket-Type", socket_type, strlen (socket_type));
+
+    //  Add identity property
+    if (options.type == ZMQ_REQ
+    ||  options.type == ZMQ_DEALER
+    ||  options.type == ZMQ_ROUTER) {
+        ptr += add_property (ptr, "Identity",
+            options.identity, options.identity_size);
+    }
+
+    const size_t command_size = ptr - command_buffer;
+    const int rc = msg_->init_size (command_size);
+    errno_assert (rc == 0);
+    memcpy (msg_->data (), command_buffer, command_size);
+    free (command_buffer);
+
+    return 0;
+}
+
+int zmq::plain_mechanism_t::process_ready_command (msg_t *msg_)
+{
+    const unsigned char *ptr = static_cast <unsigned char *> (msg_->data ());
+    size_t bytes_left = msg_->size ();
+
+    if (bytes_left < 8 || memcmp (ptr, "READY   ", 8)) {
+        errno = EPROTO;
+        return -1;
+    }
+
+    return parse_property_list (ptr + 8, bytes_left - 8);
+}
+
+int zmq::plain_mechanism_t::parse_property_list (const unsigned char *ptr,
+    size_t bytes_left)
+{
+    while (bytes_left > 1) {
+        const size_t name_length = static_cast <size_t> (*ptr);
+        ptr += 1;
+        bytes_left -= 1;
+
+        if (bytes_left < name_length)
+            break;
+        const std::string name = std::string((const char *) ptr, name_length);
+        ptr += name_length;
+        bytes_left -= name_length;
+
+        if (bytes_left < 4)
+            break;
+        const size_t value_length = static_cast <size_t> (get_uint32 (ptr));
+        ptr += 4;
+        bytes_left -= 4;
+
+        if (bytes_left < value_length)
+            break;
+        const unsigned char * const value = ptr;
+        ptr += value_length;
+        bytes_left -= value_length;
+
+        if (name == "Socket-Type") {
+            //  TODO: Implement socket type checking
+        }
+        else
+        if (name == "Identity" && options.recv_identity)
+            set_peer_identity (value, value_length);
+    }
+
+    if (bytes_left > 0) {
+        errno = EPROTO;
+        return -1;
+    }
+
+    return 0;
+}

src/plain_mechanism.hpp

+/*
+    Copyright (c) 2007-2013 Contributors as noted in the AUTHORS file
+
+    This file is part of 0MQ.
+
+    0MQ is free software; you can redistribute it and/or modify it under
+    the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.
+
+    0MQ 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_PLAIN_MECHANISM_HPP_INCLUDED__
+#define __ZMQ_PLAIN_MECHANISM_HPP_INCLUDED__
+
+#include "mechanism.hpp"
+#include "options.hpp"
+
+namespace zmq
+{
+
+    class msg_t;
+
+    class plain_mechanism_t : public mechanism_t
+    {
+    public:
+
+        plain_mechanism_t (const options_t &options_, bool as_server_);
+        virtual ~plain_mechanism_t ();
+
+        // mechanism implementation
+        virtual int next_handshake_message (msg_t *msg_);
+        virtual int process_handshake_message (msg_t *msg_);
+        virtual bool is_handshake_complete () const;
+
+    private:
+
+        enum state_t {
+            sending_hello,
+            waiting_for_hello,
+            sending_welcome,
+            waiting_for_welcome,
+            sending_initiate,
+            waiting_for_initiate,
+            sending_ready,
+            waiting_for_ready,
+            ready
+        };
+
+        state_t state;
+
+        int hello_command (msg_t *msg_) const;
+        int welcome_command (msg_t *msg_) const;
+        int initiate_command (msg_t *msg_) const;
+        int ready_command (msg_t *msg_) const;
+
+        int process_hello_command (msg_t *msg_);
+        int process_welcome_command (msg_t *msg);
+        int process_ready_command (msg_t *msg_);
+        int process_initiate_command (msg_t *msg_);
+
+        int parse_property_list (const unsigned char *ptr, size_t length);
+    };
+
+}
+
+#endif

src/stream_engine.cpp

@@ -40,6 +40,8 @@
 #include "v1_decoder.hpp"
 #include "v2_encoder.hpp"
 #include "v2_decoder.hpp"
+#include "null_mechanism.hpp"
+#include "plain_mechanism.hpp"
 #include "raw_decoder.hpp"
 #include "raw_encoder.hpp"
 #include "config.hpp"
@@ -48,8 +50,10 @@
 #include "likely.hpp"
 #include "wire.hpp"
 
-zmq::stream_engine_t::stream_engine_t (fd_t fd_, const options_t &options_, const std::string &endpoint_) :
+zmq::stream_engine_t::stream_engine_t (fd_t fd_, const options_t &options_,
+    bool as_server_, const std::string &endpoint_) :
     s (fd_),
+    as_server (as_server_),
     inpos (NULL),
     insize (0),
     decoder (NULL),
@@ -69,8 +73,9 @@ zmq::stream_engine_t::stream_engine_t (fd_t fd_, const options_t &options_, cons
     io_error (false),
     congested (false),
     subscription_required (false),
+    mechanism (NULL),
+    input_paused (false),
     output_paused (false),
-    ready_command_received (false),
     socket (NULL)
 {
     int rc = tx_msg.init ();
@@ -519,13 +524,21 @@ bool zmq::stream_engine_t::handshake ()
         alloc_assert (decoder);
 
         if (memcmp (greeting_recv + 12, "NULL\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", 20) == 0) {
-            read_msg = &stream_engine_t::send_ready_command;
-            write_msg = &stream_engine_t::receive_ready_command;
+            mechanism = new (std::nothrow) null_mechanism_t (options);
+            alloc_assert (mechanism);
+        }
+        else
+        if (memcmp (greeting_recv + 12, "PLAIN\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0", 20) == 0) {
+            mechanism = new (std::nothrow) plain_mechanism_t (options, as_server);
+            alloc_assert (mechanism);
         }
         else {
             error ();
             return false;
         }
+
+        read_msg = &stream_engine_t::next_handshake_message;
+        write_msg = &stream_engine_t::process_handshake_message;
     }
 
     // Start polling for output if necessary.
@@ -571,133 +584,59 @@ int zmq::stream_engine_t::write_identity (msg_t *msg_)
     return 0;
 }
 
-int zmq::stream_engine_t::send_ready_command (msg_t *msg_)
+int zmq::stream_engine_t::next_handshake_message (msg_t *msg_)
 {
-    unsigned char * const command_buffer = (unsigned char *) malloc (512);
-    alloc_assert (command_buffer);
-
-    unsigned char *ptr = command_buffer;
-
-    //  Add mechanism string
-    memcpy (ptr, "READY   ", 8);
-    ptr += 8;
-
-    //  Add socket type property
-    const char *socket_type = socket_type_string (options.type);
-    ptr += add_property (ptr, "Socket-Type", socket_type, strlen (socket_type));
-
-    //  Add identity property
-    if (options.type == ZMQ_REQ
-    ||  options.type == ZMQ_DEALER
-    ||  options.type == ZMQ_ROUTER) {
-        ptr += add_property (ptr, "Identity",
-            options.identity, options.identity_size);
+    zmq_assert (mechanism != NULL);
+
+    const int rc = mechanism->next_handshake_message (msg_);
+    if (rc == 0) {
+        if (mechanism->is_handshake_complete ())
+            mechanism_ready ();
+        if (input_paused) {
+            activate_in ();
+            input_paused = false;
+        }
     }
-
-    const size_t command_size = ptr - command_buffer;
-    const int rc = msg_->init_size (command_size);
-    errno_assert (rc == 0);
-    memcpy (msg_->data (), command_buffer, command_size);
-    free (command_buffer);
-
-    if (ready_command_received)
-        read_msg = &stream_engine_t::pull_msg_from_session;
     else
-        read_msg = &stream_engine_t::wait;
+    if (rc == -1) {
+        zmq_assert (errno == EAGAIN);
+        output_paused = true;
+    }
 
-    return 0;
+    return rc;
 }
 
-int zmq::stream_engine_t::receive_ready_command (msg_t *msg_)
+int zmq::stream_engine_t::process_handshake_message (msg_t *msg_)
 {
-    const unsigned char * const command_buffer =
-        static_cast <unsigned char *> (msg_->data ());
-    const size_t command_size = msg_->size ();
-
-    const unsigned char *ptr = command_buffer;
-    size_t bytes_left = command_size;
-
-    if (bytes_left < 8 || memcmp(ptr, "READY   ", 8)) {
-        errno = EPROTO;
-        return -1;
-    }
-
-    ptr += 8;
-    bytes_left -= 8;
-
-    //  Parse the property list
-    while (bytes_left > 1) {
-        const size_t name_length = static_cast <size_t> (*ptr);
-        ptr += 1;
-        bytes_left -= 1;
-
-        if (bytes_left < name_length)
-            break;
-        const std::string name = std::string((const char *) ptr, name_length);
-        ptr += name_length;
-        bytes_left -= name_length;
-
-        if (bytes_left < 4)
-            break;
-        const size_t value_length = static_cast <size_t> (get_uint32 (ptr));
-        ptr += 4;
-        bytes_left -= 4;
-
-        if (bytes_left < value_length)
-            break;
-        const unsigned char * const value = ptr;
-        ptr += value_length;
-        bytes_left -= value_length;
-
-        if (name == "Socket-Type") {
-            //  Implement socket type checking
-        }
-        else
-        if (name == "Identity") {
-            if (options.recv_identity) {
-                msg_t identity;
-                int rc = identity.init_size (value_length);
-                errno_assert (rc == 0);
-                memcpy (identity.data (), value, value_length);
-                identity.set_flags (msg_t::identity);
-                rc = session->push_msg (&identity);
-                errno_assert (rc == 0);
-            }
+    zmq_assert (mechanism != NULL);
+
+    const int rc = mechanism->process_handshake_message (msg_);
+    if (rc == 0) {
+        if (mechanism->is_handshake_complete ())
+            mechanism_ready ();
+        if (output_paused) {
+            activate_out ();
+            output_paused = false;
         }
     }
+    else
+    if (rc == -1 && errno == EAGAIN)
+        input_paused = true;
 
-    if (bytes_left > 0) {
-        errno = EPROTO;
-        return -1;
-    }
-
-    int rc = msg_->close ();
-    errno_assert (rc == 0);
-    rc = msg_->init ();
-    errno_assert (rc == 0);
-
-    write_msg = &stream_engine_t::push_msg_to_session;
-
-    ready_command_received = true;
-    if (output_paused) {
-        activate_out ();
-        output_paused = false;
-    }
-
-    return 0;
+    return rc;
 }
 
-int zmq::stream_engine_t::wait (msg_t *msg_)
+void zmq::stream_engine_t::mechanism_ready ()
 {
-    if (ready_command_received) {
-        read_msg = &stream_engine_t::pull_msg_from_session;
-        return pull_msg_from_session (msg_);
-    }
-    else {
-        output_paused = true;
-        errno = EAGAIN;
-        return -1;
+    if (options.recv_identity) {
+        msg_t identity;
+        mechanism->peer_identity (&identity);
+        const int rc = session->push_msg (&identity);
+        errno_assert (rc == 0);
     }
+
+    read_msg = &stream_engine_t::pull_msg_from_session;
+    write_msg = &stream_engine_t::push_msg_to_session;
 }
 
 int zmq::stream_engine_t::pull_msg_from_session (msg_t *msg_)
@@ -727,29 +666,6 @@ int zmq::stream_engine_t::write_subscription_msg (msg_t *msg_)
     return push_msg_to_session (msg_);
 }
 
-size_t zmq::stream_engine_t::add_property (unsigned char *ptr,
-    const char *name, const void *value, size_t value_len)
-{
-    const size_t name_len = strlen (name);
-    zmq_assert (name_len <= 255);
-    *ptr++ = static_cast <unsigned char> (name_len);
-    memcpy (ptr, name, name_len);
-    ptr += name_len;
-    zmq_assert (value_len <= (2^31) - 1);
-    put_uint32 (ptr, static_cast <uint32_t> (value_len));
-    ptr += 4;
-    memcpy (ptr, value, value_len);
-
-    return 1 + name_len + 4 + value_len;
-}
-
-const char *zmq::stream_engine_t::socket_type_string (int socket_type) {
-    const char *names [] = {"PAIR", "PUB", "SUB", "REQ", "REP", "DEALER",
-                            "ROUTER", "PULL", "PUSH", "XPUB", "XSUB"};
-    zmq_assert (socket_type >= 0 && socket_type <= 10);
-    return names [socket_type];
-}
-
 void zmq::stream_engine_t::error ()
 {
     zmq_assert (session);

src/stream_engine.hpp

@@ -43,6 +43,7 @@ namespace zmq
     class io_thread_t;
     class msg_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.
@@ -51,7 +52,8 @@ namespace zmq
     {
     public:
 
-        stream_engine_t (fd_t fd_, const options_t &options_, const std::string &endpoint);
+        stream_engine_t (fd_t fd_, const options_t &options_,
+            bool as_server_, const std::string &endpoint);
         ~stream_engine_t ();
 
         //  i_engine interface implementation.
@@ -93,13 +95,13 @@ namespace zmq
         int read_identity (msg_t *msg_);
         int write_identity (msg_t *msg_);
 
-        int send_ready_command (msg_t *msg);
-        int receive_ready_command (msg_t *msg);
+        int next_handshake_message (msg_t *msg);
+        int process_handshake_message (msg_t *msg);
 
         int pull_msg_from_session (msg_t *msg_);
         int push_msg_to_session (msg_t *msg);
 
-        int wait (msg_t *msg_);
+        void mechanism_ready ();
 
         int write_subscription_msg (msg_t *msg_);
 
@@ -111,6 +113,9 @@ namespace zmq
         //  Underlying socket.
         fd_t s;
 
+        //  True iff this is server's engine.
+        bool as_server;
+
         msg_t tx_msg;
 
         handle_t handle;
@@ -172,8 +177,10 @@ namespace zmq
         //  Needed to support old peers.
         bool subscription_required;
 
+        mechanism_t *mechanism;
+
+        bool input_paused;
         bool output_paused;
-        bool ready_command_received;
 
         // Socket
         zmq::socket_base_t *socket;

src/tcp_connecter.cpp

@@ -125,7 +125,8 @@ void zmq::tcp_connecter_t::out_event ()
     tune_tcp_keepalives (fd, options.tcp_keepalive, options.tcp_keepalive_cnt, options.tcp_keepalive_idle, options.tcp_keepalive_intvl);
 
     //  Create the engine object for this connection.
-    stream_engine_t *engine = new (std::nothrow) stream_engine_t (fd, options, endpoint);
+    stream_engine_t *engine = new (std::nothrow)
+        stream_engine_t (fd, options, false, endpoint);
     alloc_assert (engine);
 
     //  Attach the engine to the corresponding session object.

src/tcp_listener.cpp

@@ -91,7 +91,8 @@ void zmq::tcp_listener_t::in_event ()
     tune_tcp_keepalives (fd, options.tcp_keepalive, options.tcp_keepalive_cnt, options.tcp_keepalive_idle, options.tcp_keepalive_intvl);
 
     //  Create the engine object for this connection.
-    stream_engine_t *engine = new (std::nothrow) stream_engine_t (fd, options, endpoint);
+    stream_engine_t *engine = new (std::nothrow)
+        stream_engine_t (fd, options, true, endpoint);
     alloc_assert (engine);
 
     //  Choose I/O thread to run connecter in. Given that we are already