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Examples |

# echo/async_tcp_echo_server.cpp

    //
    // async_tcp_echo_server.cpp
    // ~~~~~~~~~~~~~~~~~~~~~~~~~
    //
    // Copyright (c) 2003-2007 Christopher M. Kohlhoff (chris at kohlhoff dot com)
    //
    // Distributed under the Boost Software License, Version 1.0. (See accompanying
    // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
    //

    #include <cstdlib>
    #include <iostream>
    #include <boost/bind.hpp>
    #include "asio.hpp"

    using asio::ip::tcp;

    class session
    {
    public:
      session(asio::io_service& io_service)
        : socket_(io_service)
      {
      }

      tcp::socket& socket()
      {
        return socket_;
      }

      void start()
      {
        socket_.async_read_some(asio::buffer(data_, max_length),
            boost::bind(&session::handle_read, this,
              asio::placeholders::error,
              asio::placeholders::bytes_transferred));
      }

      void handle_read(const asio::error_code& error,
          size_t bytes_transferred)
      {
        if (!error)
        {
          asio::async_write(socket_,
              asio::buffer(data_, bytes_transferred),
              boost::bind(&session::handle_write, this,
                asio::placeholders::error));
        }
        else
        {
          delete this;
        }
      }

      void handle_write(const asio::error_code& error)
      {
        if (!error)
        {
          socket_.async_read_some(asio::buffer(data_, max_length),
              boost::bind(&session::handle_read, this,
                asio::placeholders::error,
                asio::placeholders::bytes_transferred));
        }
        else
        {
          delete this;
        }
      }

    private:
      tcp::socket socket_;
      enum { max_length = 1024 };
      char data_[max_length];
    };

    class server
    {
    public:
      server(asio::io_service& io_service, short port)
        : io_service_(io_service),
          acceptor_(io_service, tcp::endpoint(tcp::v4(), port))
      {
        session* new_session = new session(io_service_);
        acceptor_.async_accept(new_session->socket(),
            boost::bind(&server::handle_accept, this, new_session,
              asio::placeholders::error));
      }

      void handle_accept(session* new_session,
          const asio::error_code& error)
      {
        if (!error)
        {
          new_session->start();
          new_session = new session(io_service_);
          acceptor_.async_accept(new_session->socket(),
              boost::bind(&server::handle_accept, this, new_session,
                asio::placeholders::error));
        }
        else
        {
          delete new_session;
        }
      }

    private:
      asio::io_service& io_service_;
      tcp::acceptor acceptor_;
    };

    int main(int argc, char* argv[])
    {
      try
      {
        if (argc != 2)
        {
          std::cerr << "Usage: async_tcp_echo_server <port>\n";
          return 1;
        }

        asio::io_service io_service;

        using namespace std; // For atoi.
        server s(io_service, atoi(argv[1]));

        io_service.run();
      }
      catch (std::exception& e)
      {
        std::cerr << "Exception: " << e.what() << "\n";
      }

      return 0;
    }

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