/*
NAME: select1
SYNOPSIS:    select1
DESCRIPTION:  The program waits until one client is connected then
              serve that client and when the second client is connected
              it serve both clients. The service is an echo service. 
              The programs exits when BOTH clients are done.
              The select statement "blocks forever" 
              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, NumClients, 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 */
   NumClients = 0;
   listen (Sock, 5);
   Sock1= accept(Sock,0,0);
   Sock1IsActive=1;
   NumClients = 1;
   printf("connected to first client\n");

   do {
      FD_ZERO(&read_template);
	if  (NumClients < 2) 
	  FD_SET(Sock,&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, NULL);
      if (nb <0) {
         perror("Error in select");
         exit(1);
      }
      if (FD_ISSET(Sock, &read_template)){
            Sock2 = accept(Sock,0,0);
            Sock2IsActive=1;
            printf("connected to second client\n");
	      NumClients=2;
	}
      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;
    }
}