EchoServerExample

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    // -------- Start of File -------- //
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    // C++ Source Code File Name: server.cpp
    // C++ Compiler Used: MSVC, BCC32, GCC, HPUX aCC, SOLARIS CC
    // Produced By: DataReel Software Development Team
    // File Creation Date: 11/02/2001
    // Date Last Modified: 06/17/2016
    // Copyright (c) 2001-2016 DataReel Software Development
    // ----------------------------------------------------------- //
    // ------------- Program Description and Details ------------- //
    // ----------------------------------------------------------- //
    /*
    This library 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 2.1 of the License, or (at your option) any later version.

    This library 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 library; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
    USA

    Simple TCP echo server using the gxSocket class.
    */
    // ----------------------------------------------------------- //
    #include "gxdlcode.h"

    #if defined (__USE_ANSI_CPP__) // Use the ANSI Standard C++ library
    #include <iostream>
    using namespace std; // Use unqualified names for Standard C++ library
    #else // Use the old iostream library by default
    #include <iostream.h>
    #endif // __USE_ANSI_CPP__

    #include <string.h>
    #include <stdlib.h>
    #include "gxsocket.h"

    int HandleClientRequest(gxSocket *server)
    // Function used to handle the client's request.
    // Returns a non-zero value if an error occurs.
    {
      // Record the client socket assigned by the kernel
      gxsSocket_t client_sock = server->GetRemoteSocket();

      const int buf_len = 255; // Receive buffer size
      char echo_buffer[buf_len];

      // Block until the client sends some data
      int bytes_read = server->RawRead(client_sock, echo_buffer, buf_len);
      if(bytes_read < 0) {
        cout << server->SocketExceptionMessage() << "\n" << flush;
        return -1;
      }

      while(bytes_read > 0) {
        // Echo the message back to the client
        if(server->RawWrite(client_sock, echo_buffer, bytes_read) < 0) {
          cout << server->SocketExceptionMessage() << "\n" << flush;
          return -1;
        }

        // Keep receiving data from the client
        bytes_read = server->RawRead(client_sock, echo_buffer, buf_len);
        if(bytes_read < 0) {
          cout << server->SocketExceptionMessage() << "\n" << flush;
          return -1;
        }
      }

      server->Close(client_sock);
      return 0;
    }

    int main(int argc, char **argv)
    {
      // Check arguments. Should be only one: the port number to bind to.
      if(argc != 2) {
        cerr << "Usage: " << argv[0] << " port" << "\n" << flush;
        return 1;
      }

      unsigned short port = (unsigned short) atoi(argv[1]);

      cout << "Constructing an echo server" << "\n" << flush;
      gxSocket server(SOCK_STREAM, port);
      if(!server) {
        cout << server.SocketExceptionMessage() << "\n" << flush;
        return 1;
      }

      // Get the host name assigned to this machine (statistical info only)
      char hostname[gxsMAX_NAME_LEN];
      int rv = server.GetHostName(hostname);
      if(rv < 0) {
        cout << server.SocketExceptionMessage() << "\n" << flush;
        return 1;
      }

      cout << "Opening echo server on host " << hostname << "\n" << flush;
      cout << "Listening on port " << port << "\n" << flush;
      cout << "Press Ctrl-C to exit" << "\n" << flush;

      // Bind the name to the socket
      rv = server.Bind();
      if(rv < 0) {
        cout << server.SocketExceptionMessage() << "\n" << flush;
        return 1;
      }

      // Listen for connections
      rv = server.Listen();
      if(rv < 0) {
        cout << server.SocketExceptionMessage() << "\n" << flush;
        return 1;
      }

      int server_loop = 1;
      while(server_loop) { // Loop forever accepting connections

        // Accept a connection and block execution until data is
        // received from a client connection to this port.
        rv = server.Accept();
        if(rv < 0) {
          cout << server.SocketExceptionMessage() << "\n" << flush;
          break;
        }

        // Get the client info (statistical info only)
        char client_name[gxsMAX_NAME_LEN]; int r_port = -1;
        server.GetClientInfo(client_name, r_port);
        cout << "Receiving data from " << client_name
    	 << " remote port " << r_port << "\n" << flush;

        // Handle the clients request
        HandleClientRequest(&server);
      }

      cout << "Exiting..." << "\n" << flush;
      server.Close(); // Close the socket connection
      server.ReleaseSocketLibrary();
      return 0;
    }
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