TCP_server.cpp

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/***********************************************************************/
#include "system_configuration.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
#ifndef _WIN32
# include <unistd.h>
# include <netdb.h>
# include <netinet/in.h>
# include <sys/socket.h>
#else
# include <winsock2.h>
  typedef int socklen_t;
# define close(x) closesocket(x)  // in WinSock2.h the name of 'close' is 'closesocket'
#endif
#include <sys/types.h>
#include "TCP_server.h"
 
int listening_socket_file_descriptor;
struct sockaddr_in servaddr, cli;
#ifdef _WIN32 // _MSC_VER
# define   sleep(x)   Sleep(x)
#endif
socklen_t len;
 
  enum {MAX_CLIENTS=10};
int TCP_clients[MAX_CLIENTS];
int number_of_TCP_clients = 0;
 
bool accept_TCP_client( bool wait_for_client)
{
  if( number_of_TCP_clients >= MAX_CLIENTS)
    return false;
 
  int client_descriptor;
  while( true)
    {
      client_descriptor = accept(listening_socket_file_descriptor, (sockaddr*)&cli, &len);
      if( client_descriptor > 0)
    {
        printf("New client accepted\n");
#if _WIN32
        u_long val = 1;
        bool bOk = ioctlsocket(client_descriptor, FIONBIO, &val) == 0;
#endif
        break;
    }
      if( ! wait_for_client)
      return false;
      sleep(1);
  }
 
  TCP_clients[number_of_TCP_clients]=client_descriptor;
  ++number_of_TCP_clients;
  return true;
}
 
bool open_TCP_port(void)
{
 
#ifdef _WIN32
  static bool initialised = false;
  if (!initialised) {
    WSADATA data;
    WSAStartup(MAKEWORD(2, 2), &data);
    initialised = true;
  }
  const int type = SOCK_STREAM; // SOCK_NONBLOCK is not available on Windows!
#else
  const int type = SOCK_STREAM | SOCK_NONBLOCK;
#endif  // _WIN32
  listening_socket_file_descriptor = socket(AF_INET, type, 0);
    if (listening_socket_file_descriptor == -1) {
        printf("Socket creation failed\n");
        return false;
    }
 
    int opt = 0;
    if( setsockopt( listening_socket_file_descriptor, SOL_SOCKET, SO_REUSEADDR, (char *)&opt, sizeof(opt)) < 0 )
    {
        printf("Socket modification failed\n");
        return false;
    }
#if _WIN32
    u_long val = 1;
    bool bOk = ioctlsocket(listening_socket_file_descriptor, FIONBIO, &val) == 0;
#endif
 
    memset(&servaddr, 0, sizeof(servaddr));
 
    servaddr.sin_family = AF_INET;
    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
    servaddr.sin_port = htons(TCP_PORT);
 
    if ((bind(listening_socket_file_descriptor, (sockaddr*)&servaddr, sizeof(servaddr))) != 0) {
        printf("Bind failed\n");
        return false;
    }
 
    if ((listen(listening_socket_file_descriptor, 2)) != 0) {
        printf("Listen failed\n");
        return false;
    }
    else
        printf("Server listening\n");
 
    len = sizeof(cli);
    return true;
}
 
void write_TCP_port( char * data, unsigned length)
{
  accept_TCP_client(false);
 
  int written_bytes;
  unsigned remaining_length;
  char * data_tail;
 
  for( int client_index = 0; client_index < number_of_TCP_clients; ++client_index)
    {
      data_tail = data;
      remaining_length = length;
      do
    {
#ifdef _WIN32
      written_bytes = send(TCP_clients[client_index], data_tail, remaining_length, 0);
#else
      written_bytes = write(TCP_clients[client_index], data_tail, remaining_length);
#endif
    if( written_bytes < 0)
      break;
        // continue; // we have got some error and give up
      remaining_length -= written_bytes;
      data_tail += written_bytes;
    }
      while( remaining_length > 0);
    }
}
 
void close_TCP_port(void)
{
  if( listening_socket_file_descriptor)
    close(listening_socket_file_descriptor);
 
  for( int client_index = 0; client_index < number_of_TCP_clients; ++client_index)
    close( TCP_clients[client_index]);
}