//==================================================== file = tcpClient.c =====
//=  A message "client" program to demonstrate sockets programming            =
//=============================================================================
//=  Notes:                                                                   =
//=    1) This program conditionally compiles for Winsock and BSD sockets.    =
//=       Set the initial #define to WIN or BSD as appropriate.               =
//=    2) This program needs tcpServer to be running on another host.         =
//=       Program tcpServer must be started first.                            =
//=    3) This program assumes that the IP address of the host running        =
//=       tcpServer is defined in "#define IP_ADDR"                           =
//=    4) The steps #'s correspond to lecture topics.                         =
//=---------------------------------------------------------------------------=
//=  Example execution: (tcpServer and tcpClient running on host 127.0.0.1)   =
//=    Received from server: This is a message from SERVER to CLIENT          =
//=---------------------------------------------------------------------------=
//=  Build: bcc32 tcpClient.c or cl tcpClient.c wsock32.lib for Winsock       =
//=         gcc tcpClient.c -lnsl for BSD                                     =
//=---------------------------------------------------------------------------=
//=  Execute: tcpClient                                                       =
//=---------------------------------------------------------------------------=
//=  Author: Ken Christensen                                                  =
//=          University of South Florida                                      =
//=          WWW: http://www.csee.usf.edu/~christen                           =
//=          Email: christen@csee.usf.edu                                     =
//=---------------------------------------------------------------------------=
//=  History:  KJC (08/02/08) - Genesis (from client.c)                       =
//=            KJC (09/09/09) - Minor clean-up                                =
//=============================================================================
#define  WIN                // WIN for Winsock and BSD for BSD sockets

//----- Include files ---------------------------------------------------------
#include <stdio.h>          // Needed for printf()
#include <string.h>         // Needed for memcpy() and strcpy()
#ifdef WIN
  #include <windows.h>      // Needed for all Winsock stuff
#endif
#ifdef BSD
  #include <sys/types.h>    // Needed for sockets stuff
  #include <netinet/in.h>   // Needed for sockets stuff
  #include <sys/socket.h>   // Needed for sockets stuff
  #include <arpa/inet.h>    // Needed for sockets stuff
  #include <fcntl.h>        // Needed for sockets stuff
  #include <netdb.h>        // Needed for sockets stuff
#endif

//----- Defines ---------------------------------------------------------------
#define  PORT_NUM         1050   // Port number used at the server
#define  IP_ADDR    "127.0.0.1"  // IP address of server (*** HARDWIRED ***)

//===== Main program ==========================================================
void main(void)
{
#ifdef WIN
  WORD wVersionRequested = MAKEWORD(1,1);       // Stuff for WSA functions
  WSADATA wsaData;                              // Stuff for WSA functions
#endif
  int                  client_s;        // Client socket descriptor
  struct sockaddr_in   server_addr;     // Server Internet address
  char                 out_buf[4096];   // Output buffer for data
  char                 in_buf[4096];    // Input buffer for data
  int                  retcode;         // Return code

#ifdef WIN
  // This stuff initializes winsock
  WSAStartup(wVersionRequested, &wsaData);
#endif

  // >>> Step #1 <<<
  // Create a client socket
  //   - AF_INET is Address Family Internet and SOCK_STREAM is streams
  client_s = socket(AF_INET, SOCK_STREAM, 0);
  if (client_s < 0)
  {
    printf("*** ERROR - socket() failed \n");
    exit(-1);
  }

  // >>> Step #2 <<<
  // Fill-in the server's address information and do a connect with the
  // listening server using the client socket - the connect() will block.
  server_addr.sin_family = AF_INET;                 // Address family to use
  server_addr.sin_port = htons(PORT_NUM);           // Port num to use
  server_addr.sin_addr.s_addr = inet_addr(IP_ADDR); // IP address to use
  retcode = connect(client_s, (struct sockaddr *)&server_addr,
    sizeof(server_addr));
  if (retcode < 0)
  {
    printf("*** ERROR - connect() failed \n");
    exit(-1);
  }

  // >>> Step #3 <<<
  // Receive from the server using the client socket
  retcode = recv(client_s, in_buf, sizeof(in_buf), 0);
  if (retcode < 0)
  {
    printf("*** ERROR - recv() failed \n");
    exit(-1);
  }

  // Output the received message
  printf("Received from server: %s \n", in_buf);

  // >>> Step #4 <<<
  // Send to the server using the client socket
  strcpy(out_buf, "This is a reply message from CLIENT to SERVER");
  retcode = send(client_s, out_buf, (strlen(out_buf) + 1), 0);
  if (retcode < 0)
  {
    printf("*** ERROR - send() failed \n");
    exit(-1);
  }

  // >>> Step #5 <<<
  // Close the client socket
#ifdef WIN
  retcode = closesocket(client_s);
  if (retcode < 0)
  {
    printf("*** ERROR - closesocket() failed \n");
    exit(-1);
  }
#endif
#ifdef BSD
  retcode = close(client_s);
  if (retcode < 0)
  {
    printf("*** ERROR - close() failed \n");
    exit(-1);
  }
#endif

#ifdef WIN
  // Clean-up winsock
  WSACleanup();
#endif
}