net_helper.h

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// Copyright (c) 2006-2013, Andrey N. Sabelnikov, www.sabelnikov.net
// All rights reserved.
// 
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * 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.
// * Neither the name of the Andrey N. Sabelnikov nor the
// names of its contributors may be used to endorse or promote products
// derived from this software without specific prior written permission.
// 
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT OWNER  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.
// 
 
 
 
 
#pragma once
 
//#include <Winsock2.h>
//#include <Ws2tcpip.h>
#include <string>
#include <boost/version.hpp>
#include <boost/asio/io_service.hpp>
#include <boost/asio/ip/tcp.hpp>
#include <boost/asio/read.hpp>
#include <boost/asio/ssl.hpp>
#include <boost/asio/steady_timer.hpp>
#include <boost/thread/future.hpp>
#include <boost/lambda/bind.hpp>
#include <boost/lambda/lambda.hpp>
#include <boost/interprocess/detail/atomic.hpp>
#include <boost/system/error_code.hpp>
#include <functional>
#include "net/net_utils_base.h"
#include "net/net_ssl.h"
#include "misc_language.h"
 
#undef ELECTRONEUM_DEFAULT_LOG_CATEGORY
#define ELECTRONEUM_DEFAULT_LOG_CATEGORY "net"
 
#ifndef MAKE_IP
#define MAKE_IP( a1, a2, a3, a4 )   (a1|(a2<<8)|(a3<<16)|(a4<<24))
#endif
 
 
namespace epee
{
namespace net_utils
{
    struct direct_connect
    {
        boost::unique_future<boost::asio::ip::tcp::socket>
            operator()(const std::string& addr, const std::string& port, boost::asio::steady_timer&) const;
    };
 
 
  class blocked_mode_client
    {
        enum try_connect_result_t
        {
            CONNECT_SUCCESS,
            CONNECT_FAILURE,
            CONNECT_NO_SSL,
        };
 
        
        
                struct handler_obj
                {
                    handler_obj(boost::system::error_code& error,   size_t& bytes_transferred):ref_error(error), ref_bytes_transferred(bytes_transferred)
                    {}
                    handler_obj(const handler_obj& other_obj):ref_error(other_obj.ref_error), ref_bytes_transferred(other_obj.ref_bytes_transferred)
                    {}
 
                    boost::system::error_code& ref_error;
                    size_t& ref_bytes_transferred;
 
                    void operator()(const boost::system::error_code& error, // Result of operation.
                        std::size_t bytes_transferred           // Number of bytes read.
                        )
                    {
                        ref_error = error;
                        ref_bytes_transferred = bytes_transferred;
                    }
                };
 
    public:
        inline
            blocked_mode_client() :
                m_io_service(),
                m_ctx(boost::asio::ssl::context::tlsv12),
                m_connector(direct_connect{}),
                m_ssl_socket(new boost::asio::ssl::stream<boost::asio::ip::tcp::socket>(m_io_service, m_ctx)),
                m_ssl_options(epee::net_utils::ssl_support_t::e_ssl_support_autodetect),
                m_initialized(true),
                m_connected(false),
                m_deadline(m_io_service),
                m_shutdowned(0),
                m_bytes_sent(0),
                m_bytes_received(0)
        {
        }

        using connect_func = boost::unique_future<boost::asio::ip::tcp::socket>(const std::string&, const std::string&, boost::asio::steady_timer&);
 
        inline
            ~blocked_mode_client()
        {
            //profile_tools::local_coast lc("~blocked_mode_client()", 3);
            try { shutdown(); }
            catch(...) { /* ignore */ }
        }
 
        inline void set_ssl(ssl_options_t ssl_options)
        {
            if (ssl_options)
                m_ctx = ssl_options.create_context();
            else
                m_ctx = boost::asio::ssl::context(boost::asio::ssl::context::tlsv12);
            m_ssl_options = std::move(ssl_options);
        }
 
    inline
      bool connect(const std::string& addr, int port, std::chrono::milliseconds timeout)
    {
      return connect(addr, std::to_string(port), timeout);
    }
 
    inline
            try_connect_result_t try_connect(const std::string& addr, const std::string& port, std::chrono::milliseconds timeout, epee::net_utils::ssl_support_t ssl_support)
        {
                m_deadline.expires_from_now(timeout);
                boost::unique_future<boost::asio::ip::tcp::socket> connection = m_connector(addr, port, m_deadline);
                for (;;)
                {
                    m_io_service.reset();
                    m_io_service.run_one();
 
                    if (connection.is_ready())
                        break;
                }
 
                m_ssl_socket->next_layer() = connection.get();
                m_deadline.cancel();
                if (m_ssl_socket->next_layer().is_open())
                {
                    m_connected = true;
                    m_deadline.expires_at(std::chrono::steady_clock::time_point::max());
                    // SSL Options
                    if (ssl_support == epee::net_utils::ssl_support_t::e_ssl_support_enabled || ssl_support == epee::net_utils::ssl_support_t::e_ssl_support_autodetect)
                    {
                        if (!m_ssl_options.handshake(*m_ssl_socket, boost::asio::ssl::stream_base::client, addr))
                        {
                            if (ssl_support == epee::net_utils::ssl_support_t::e_ssl_support_autodetect)
                            {
                                boost::system::error_code ignored_ec;
                                m_ssl_socket->next_layer().shutdown(boost::asio::ip::tcp::socket::shutdown_both, ignored_ec);
                                m_ssl_socket->next_layer().close();
                                m_connected = false;
                                return CONNECT_NO_SSL;
                            }
                            else
                            {
                                MWARNING("Failed to establish SSL connection");
                                m_connected = false;
                                return CONNECT_FAILURE;
                            }
                        }
                    }
                    return CONNECT_SUCCESS;
                }else
                {
                    MWARNING("Some problems at connect, expected open socket");
                    return CONNECT_FAILURE;
                }
 
        }
 
    inline
            bool connect(const std::string& addr, const std::string& port, std::chrono::milliseconds timeout)
        {
            m_connected = false;
            try
            {
                m_ssl_socket->next_layer().close();
 
                // Set SSL options
                // disable sslv2
                m_ssl_socket.reset(new boost::asio::ssl::stream<boost::asio::ip::tcp::socket>(m_io_service, m_ctx));
 
                // Get a list of endpoints corresponding to the server name.
 
                try_connect_result_t try_connect_result = try_connect(addr, port, timeout, m_ssl_options.support);
                if (try_connect_result == CONNECT_FAILURE)
                    return false;
                if (m_ssl_options.support == epee::net_utils::ssl_support_t::e_ssl_support_autodetect)
                {
                    if (try_connect_result == CONNECT_NO_SSL)
                    {
                        MERROR("SSL handshake failed on an autodetect connection, reconnecting without SSL");
                        m_ssl_options.support = epee::net_utils::ssl_support_t::e_ssl_support_disabled;
                        if (try_connect(addr, port, timeout, m_ssl_options.support) != CONNECT_SUCCESS)
                            return false;
                    }
                }
            }
            catch(const boost::system::system_error& er)
            {
                MDEBUG("Some problems at connect, message: " << er.what());
                return false;
            }
            catch(...)
            {
                MDEBUG("Some fatal problems.");
                return false;
            }
 
            return true;
        }

        void set_connector(std::function<connect_func> connector)
        {
            m_connector = std::move(connector);
        }
 
        inline 
        bool disconnect()
        {
            try
            {   
                if(m_connected)
                {
                    m_connected = false;
                    if(m_ssl_options)
                        shutdown_ssl();
                    m_ssl_socket->next_layer().shutdown(boost::asio::ip::tcp::socket::shutdown_both);
                }
            }
            catch(const boost::system::system_error& /*er*/)
            {
                //LOG_ERROR("Some problems at disconnect, message: " << er.what());
                return false;
            }
            catch(...)
            {
                //LOG_ERROR("Some fatal problems.");
                return false;
            }
            return true;
        }
 
 
        inline 
        bool send(const std::string& buff, std::chrono::milliseconds timeout)
        {
 
            try
            {
                m_deadline.expires_from_now(timeout);
 
                // Set up the variable that receives the result of the asynchronous
                // operation. The error code is set to would_block to signal that the
                // operation is incomplete. Asio guarantees that its asynchronous
                // operations will never fail with would_block, so any other value in
                // ec indicates completion.
                boost::system::error_code ec = boost::asio::error::would_block;
 
                // Start the asynchronous operation itself. The boost::lambda function
                // object is used as a callback and will update the ec variable when the
                // operation completes. The blocking_udp_client.cpp example shows how you
                // can use boost::bind rather than boost::lambda.
                async_write(buff.c_str(), buff.size(), ec);
 
                // Block until the asynchronous operation has completed.
                while (ec == boost::asio::error::would_block)
                {
                    m_io_service.reset();
                    m_io_service.run_one(); 
                }
 
                if (ec)
                {
                    LOG_PRINT_L3("Problems at write: " << ec.message());
          m_connected = false;
                    return false;
                }else
                {
                    m_deadline.expires_at(std::chrono::steady_clock::time_point::max());
                    m_bytes_sent += buff.size();
                }
            }
 
            catch(const boost::system::system_error& er)
            {
                LOG_ERROR("Some problems at connect, message: " << er.what());
                return false;
            }
            catch(...)
            {
                LOG_ERROR("Some fatal problems.");
                return false;
            }
 
            return true;
        }
 
        inline 
            bool send(const void* data, size_t sz)
        {
            try
            {
                /*
                m_deadline.expires_from_now(boost::posix_time::milliseconds(m_reciev_timeout));
 
                // Set up the variable that receives the result of the asynchronous
                // operation. The error code is set to would_block to signal that the
                // operation is incomplete. Asio guarantees that its asynchronous
                // operations will never fail with would_block, so any other value in
                // ec indicates completion.
                boost::system::error_code ec = boost::asio::error::would_block;
 
                // Start the asynchronous operation itself. The boost::lambda function
                // object is used as a callback and will update the ec variable when the
                // operation completes. The blocking_udp_client.cpp example shows how you
                // can use boost::bind rather than boost::lambda.
                boost::asio::async_write(m_socket, boost::asio::buffer(data, sz), boost::lambda::var(ec) = boost::lambda::_1);
 
                // Block until the asynchronous operation has completed.
                while (ec == boost::asio::error::would_block)
                {
                    m_io_service.run_one();
                }
                */
                boost::system::error_code ec;
 
                size_t writen = write(data, sz, ec);
 
                if (!writen || ec)
                {
                    LOG_PRINT_L3("Problems at write: " << ec.message());
          m_connected = false;
                    return false;
                }else
                {
                    m_deadline.expires_at(std::chrono::steady_clock::time_point::max());
                    m_bytes_sent += sz;
                }
            }
 
            catch(const boost::system::system_error& er)
            {
                LOG_ERROR("Some problems at send, message: " << er.what());
        m_connected = false;
                return false;
            }
            catch(...)
            {
                LOG_ERROR("Some fatal problems.");
                return false;
            }
 
            return true;
        }
 
        bool is_connected(bool *ssl = NULL)
        {
            if (!m_connected || !m_ssl_socket->next_layer().is_open())
                return false;
            if (ssl)
                *ssl = m_ssl_options.support != ssl_support_t::e_ssl_support_disabled;
            return true;
        }
 
        inline 
        bool recv(std::string& buff, std::chrono::milliseconds timeout)
        {
 
            try
            {
                // Set a deadline for the asynchronous operation. Since this function uses
                // a composed operation (async_read_until), the deadline applies to the
                // entire operation, rather than individual reads from the socket.
                m_deadline.expires_from_now(timeout);
 
                // Set up the variable that receives the result of the asynchronous
                // operation. The error code is set to would_block to signal that the
                // operation is incomplete. Asio guarantees that its asynchronous
                // operations will never fail with would_block, so any other value in
                // ec indicates completion.
                //boost::system::error_code ec = boost::asio::error::would_block;
 
                // Start the asynchronous operation itself. The boost::lambda function
                // object is used as a callback and will update the ec variable when the
                // operation completes. The blocking_udp_client.cpp example shows how you
                // can use boost::bind rather than boost::lambda.
 
                boost::system::error_code ec = boost::asio::error::would_block;
                size_t bytes_transfered = 0;
            
                handler_obj hndlr(ec, bytes_transfered);
 
                static const size_t max_size = 16384;
                buff.resize(max_size);
                
                async_read(&buff[0], max_size, boost::asio::transfer_at_least(1), hndlr);
 
                // Block until the asynchronous operation has completed.
                while (ec == boost::asio::error::would_block && !boost::interprocess::ipcdetail::atomic_read32(&m_shutdowned))
                {
                    m_io_service.reset();
                    m_io_service.run_one(); 
                }
 
 
                if (ec)
                {
                    MTRACE("READ ENDS: Connection err_code " << ec.value());
                    if(ec == boost::asio::error::eof)
                    {
                      MTRACE("Connection err_code eof.");
                      //connection closed there, empty
                      buff.clear();
                      return true;
                    }
 
                    MDEBUG("Problems at read: " << ec.message());
                    m_connected = false;
                    return false;
                }else
                {
                    MTRACE("READ ENDS: Success. bytes_tr: " << bytes_transfered);
                    m_deadline.expires_at(std::chrono::steady_clock::time_point::max());
                }
 
                /*if(!bytes_transfered)
                    return false;*/
 
                m_bytes_received += bytes_transfered;
                buff.resize(bytes_transfered);
                return true;
            }
 
            catch(const boost::system::system_error& er)
            {
                LOG_ERROR("Some problems at read, message: " << er.what());
        m_connected = false;
                return false;
            }
            catch(...)
            {
                LOG_ERROR("Some fatal problems at read.");
                return false;
            }
 
 
 
            return false;
 
        }
 
        inline bool recv_n(std::string& buff, int64_t sz, std::chrono::milliseconds timeout)
        {
 
            try
            {
                // Set a deadline for the asynchronous operation. Since this function uses
                // a composed operation (async_read_until), the deadline applies to the
                // entire operation, rather than individual reads from the socket.
                m_deadline.expires_from_now(timeout);
 
                // Set up the variable that receives the result of the asynchronous
                // operation. The error code is set to would_block to signal that the
                // operation is incomplete. Asio guarantees that its asynchronous
                // operations will never fail with would_block, so any other value in
                // ec indicates completion.
                //boost::system::error_code ec = boost::asio::error::would_block;
 
                // Start the asynchronous operation itself. The boost::lambda function
                // object is used as a callback and will update the ec variable when the
                // operation completes. The blocking_udp_client.cpp example shows how you
                // can use boost::bind rather than boost::lambda.
 
                buff.resize(static_cast<size_t>(sz));
                boost::system::error_code ec = boost::asio::error::would_block;
                size_t bytes_transfered = 0;
 
                
                handler_obj hndlr(ec, bytes_transfered);
                async_read((char*)buff.data(), buff.size(), boost::asio::transfer_at_least(buff.size()), hndlr);
                
                // Block until the asynchronous operation has completed.
                while (ec == boost::asio::error::would_block && !boost::interprocess::ipcdetail::atomic_read32(&m_shutdowned))
                {
                    m_io_service.run_one(); 
                }
 
                if (ec)
                {
                    LOG_PRINT_L3("Problems at read: " << ec.message());
          m_connected = false;
                    return false;
                }else
                {
                    m_deadline.expires_at(std::chrono::steady_clock::time_point::max());
                }
 
                m_bytes_received += bytes_transfered;
                if(bytes_transfered != buff.size())
                {
                    LOG_ERROR("Transferred mismatch with transfer_at_least value: m_bytes_transferred=" << bytes_transfered << " at_least value=" << buff.size());
                    return false;
                }
 
                return true;
            }
 
            catch(const boost::system::system_error& er)
            {
                LOG_ERROR("Some problems at read, message: " << er.what());
        m_connected = false;
                return false;
            }
            catch(...)
            {
                LOG_ERROR("Some fatal problems at read.");
                return false;
            }
 
 
 
            return false;
        }
        
        bool shutdown()
        {
            m_deadline.cancel();
            boost::system::error_code ec;
            if(m_ssl_options.support != ssl_support_t::e_ssl_support_disabled)
                shutdown_ssl();
            m_ssl_socket->next_layer().cancel(ec);
            if(ec)
                MDEBUG("Problems at cancel: " << ec.message());
            m_ssl_socket->next_layer().shutdown(boost::asio::ip::tcp::socket::shutdown_both, ec);
            if(ec)
                MDEBUG("Problems at shutdown: " << ec.message());
            m_ssl_socket->next_layer().close(ec);
            if(ec)
                MDEBUG("Problems at close: " << ec.message());
            boost::interprocess::ipcdetail::atomic_write32(&m_shutdowned, 1);
      m_connected = false;
            return true;
        }
        
        boost::asio::io_service& get_io_service()
        {
            return m_io_service;
        }
 
        boost::asio::ip::tcp::socket& get_socket()
        {
            return m_ssl_socket->next_layer();
        }
 
        uint64_t get_bytes_sent() const
        {
            return m_bytes_sent;
        }
 
        uint64_t get_bytes_received() const
        {
            return m_bytes_received;
        }
 
    private:
 
        void check_deadline()
        {
            // Check whether the deadline has passed. We compare the deadline against
            // the current time since a new asynchronous operation may have moved the
            // deadline before this actor had a chance to run.
            if (m_deadline.expires_at() <= std::chrono::steady_clock::now())
            {
                // The deadline has passed. The socket is closed so that any outstanding
                // asynchronous operations are cancelled. This allows the blocked
                // connect(), read_line() or write_line() functions to return.
                LOG_PRINT_L3("Timed out socket");
        m_connected = false;
                m_ssl_socket->next_layer().close();
 
                // There is no longer an active deadline. The expiry is set to positive
                // infinity so that the actor takes no action until a new deadline is set.
                m_deadline.expires_at(std::chrono::steady_clock::time_point::max());
            }
 
            // Put the actor back to sleep.
            m_deadline.async_wait(boost::bind(&blocked_mode_client::check_deadline, this));
        }
 
        void shutdown_ssl() {
            // ssl socket shutdown blocks if server doesn't respond. We close after 2 secs
            boost::system::error_code ec = boost::asio::error::would_block;
            m_deadline.expires_from_now(std::chrono::milliseconds(2000));
            m_ssl_socket->async_shutdown(boost::lambda::var(ec) = boost::lambda::_1);
            while (ec == boost::asio::error::would_block)
            {
                m_io_service.reset();
                m_io_service.run_one();
            }
            // Ignore "short read" error
            if (ec.category() == boost::asio::error::get_ssl_category() &&
                ec.value() !=
#if BOOST_VERSION >= 106200
                boost::asio::ssl::error::stream_truncated
#else // older Boost supports only OpenSSL 1.0, so 1.0-only macros are appropriate
                ERR_PACK(ERR_LIB_SSL, 0, SSL_R_SHORT_READ)
#endif
                )
                MDEBUG("Problems at ssl shutdown: " << ec.message());
        }
        
    protected:
        bool write(const void* data, size_t sz, boost::system::error_code& ec)
        {
            bool success;
            if(m_ssl_options.support != ssl_support_t::e_ssl_support_disabled)
                success = boost::asio::write(*m_ssl_socket, boost::asio::buffer(data, sz), ec);
            else
                success = boost::asio::write(m_ssl_socket->next_layer(), boost::asio::buffer(data, sz), ec);
            return success;
        }
        
        void async_write(const void* data, size_t sz, boost::system::error_code& ec) 
        {
            if(m_ssl_options.support != ssl_support_t::e_ssl_support_disabled)
                boost::asio::async_write(*m_ssl_socket, boost::asio::buffer(data, sz), boost::lambda::var(ec) = boost::lambda::_1);
            else
                boost::asio::async_write(m_ssl_socket->next_layer(), boost::asio::buffer(data, sz), boost::lambda::var(ec) = boost::lambda::_1);
        }
        
        void async_read(char* buff, size_t sz, boost::asio::detail::transfer_at_least_t transfer_at_least, handler_obj& hndlr)
        {
            if(m_ssl_options.support == ssl_support_t::e_ssl_support_disabled)
                boost::asio::async_read(m_ssl_socket->next_layer(), boost::asio::buffer(buff, sz), transfer_at_least, hndlr);
            else
                boost::asio::async_read(*m_ssl_socket, boost::asio::buffer(buff, sz), transfer_at_least, hndlr);
            
        }
        
    protected:
        boost::asio::io_service m_io_service;
        boost::asio::ssl::context m_ctx;
        std::shared_ptr<boost::asio::ssl::stream<boost::asio::ip::tcp::socket>> m_ssl_socket;
        std::function<connect_func> m_connector;
        ssl_options_t m_ssl_options;
        bool m_initialized;
        bool m_connected;
        boost::asio::steady_timer m_deadline;
        volatile uint32_t m_shutdowned;
        std::atomic<uint64_t> m_bytes_sent;
        std::atomic<uint64_t> m_bytes_received;
    };
 
 
    /************************************************************************/
    /*                                                                      */
    /************************************************************************/
    class async_blocked_mode_client: public blocked_mode_client
    {
    public:
        async_blocked_mode_client():m_send_deadline(blocked_mode_client::m_io_service)
        {
 
            // No deadline is required until the first socket operation is started. We
            // set the deadline to positive infinity so that the actor takes no action
            // until a specific deadline is set.
            m_send_deadline.expires_at(boost::posix_time::pos_infin);
 
            // Start the persistent actor that checks for deadline expiry.
            check_send_deadline();
        }
        ~async_blocked_mode_client()
        {
            m_send_deadline.cancel();
        }
        
        bool shutdown()
        {
            blocked_mode_client::shutdown();
            m_send_deadline.cancel();
            return true;
        }
 
        inline 
            bool send(const void* data, size_t sz)
        {
            try
            {
                /*
                m_send_deadline.expires_from_now(boost::posix_time::milliseconds(m_reciev_timeout));
 
                // Set up the variable that receives the result of the asynchronous
                // operation. The error code is set to would_block to signal that the
                // operation is incomplete. Asio guarantees that its asynchronous
                // operations will never fail with would_block, so any other value in
                // ec indicates completion.
                boost::system::error_code ec = boost::asio::error::would_block;
 
                // Start the asynchronous operation itself. The boost::lambda function
                // object is used as a callback and will update the ec variable when the
                // operation completes. The blocking_udp_client.cpp example shows how you
                // can use boost::bind rather than boost::lambda.
                boost::asio::async_write(m_socket, boost::asio::buffer(data, sz), boost::lambda::var(ec) = boost::lambda::_1);
 
                // Block until the asynchronous operation has completed.
                while(ec == boost::asio::error::would_block)
                {
                    m_io_service.run_one();
                }*/
                
                boost::system::error_code ec;
 
                size_t writen = write(data, sz, ec);
                
                if (!writen || ec)
                {
                    LOG_PRINT_L3("Problems at write: " << ec.message());
                    return false;
                }else
                {
                    m_send_deadline.expires_at(boost::posix_time::pos_infin);
                }
            }
 
            catch(const boost::system::system_error& er)
            {
                LOG_ERROR("Some problems at connect, message: " << er.what());
                return false;
            }
            catch(...)
            {
                LOG_ERROR("Some fatal problems.");
                return false;
            }
 
            return true;
        }
 
 
    private:
 
        boost::asio::deadline_timer m_send_deadline;
 
        void check_send_deadline()
        {
            // Check whether the deadline has passed. We compare the deadline against
            // the current time since a new asynchronous operation may have moved the
            // deadline before this actor had a chance to run.
            if (m_send_deadline.expires_at() <= boost::asio::deadline_timer::traits_type::now())
            {
                // The deadline has passed. The socket is closed so that any outstanding
                // asynchronous operations are cancelled. This allows the blocked
                // connect(), read_line() or write_line() functions to return.
                LOG_PRINT_L3("Timed out socket");
                m_ssl_socket->next_layer().close();
 
                // There is no longer an active deadline. The expiry is set to positive
                // infinity so that the actor takes no action until a new deadline is set.
                m_send_deadline.expires_at(boost::posix_time::pos_infin);
            }
 
            // Put the actor back to sleep.
            m_send_deadline.async_wait(boost::bind(&async_blocked_mode_client::check_send_deadline, this));
        }
    };
}
}