/*
NAME: select0
SYNOPSIS:    select0
DESCRIPTION:  The program waits until two clients are connected then
              And only them its serve both clients by echoing to each
              Whatever it sends. 
              The programs exits when BOTH clients are done.
              The select statement "blocks 1 second" 
              until one socket has  activity
*/

#include "def"
main()
{
   fd_set read_template;
   struct timeval wait;
   struct   sockaddr_in server;
   char   buf[102];
   int   Sock, length, Sock1,Sock2, nb, Sock1IsActive,Sock2IsActive;

/* create the accepting socket */
   Sock = socket (PF_INET,SOCK_STREAM,0);
   if ( Sock < 0 ) {
      perror("opening stream Socket");
      exit(0);
   }
/** bind Socket using wildcards and any available port */
   server.sin_family = AF_INET;
   server.sin_addr.s_addr = INADDR_ANY;
   server.sin_port = 0;
   if ( bind (Sock, (SA *)&server, sizeof(server)) ) {
      perror("binding stream Socket");
   }
/** Find out assigned port number and print it out */
   length = sizeof(server);
   if ( getsockname (Sock,(SA *)&server,&length) ) {
      perror("getting Socket name");
      exit(0);
   }
   printf("Socket has port #%d\n", ntohs(server.sin_port));
   printf("...waiting for connection ...\n");

/** Start accepting connections */
   listen (Sock, 5);
   Sock1= accept(Sock,0,0);
   Sock1IsActive=1;
   printf("connected to first client\n");
   Sock2 = accept(Sock,0,0);
   Sock2IsActive=1;
   printf("connected to second client\n");
   wait.tv_sec = 1;
   wait.tv_usec = 0;
   do {
      FD_ZERO(&read_template);
      if (Sock1IsActive) FD_SET(Sock1,&read_template);
      if (Sock2IsActive) FD_SET(Sock2,&read_template);
      nb = select(FD_SETSIZE, &read_template, (fd_set *) 0, (fd_set *) 0,&wait);
      if (nb <0) {
         perror("Error in select");
         exit(1);
      }
      if (nb != 0) {      /* 0 time out */
         if(FD_ISSET(Sock1, &read_template)){
		EchoServe(Sock1, &Sock1IsActive);
         }
         if(FD_ISSET(Sock2, &read_template)){
		EchoServe(Sock2, &Sock2IsActive);
         }

      }
   }   while ( Sock1IsActive || Sock2IsActive );
   printf("Both clients are done ...exiting...\n");
   close(Sock1);
   close(Sock2);
   exit(0);
}
EchoServe(Psock, SockIsActive)
int Psock, *SockIsActive;

{
  char buf[512];
  int rc;

/** get data from  client and echo it back */
    if( (rc=recv(Psock, buf, sizeof (buf), 0)) < 0)
      perror("receiving stream  message");
    if (rc > 0){
      buf[rc]=NULL;
      printf("Received: %s\n", buf);
      if (send(Psock, buf, rc, 0) <0 )
        perror("sending stream message");
    }
    else {
      printf("Disconnected..\n");
      close (Psock);
      *SockIsActive=0;
    }
}