socket_server.c

socket_server()
{
	int sockfd, newsockfd, portno;
	struct sockaddr_in serv_addr, cli_addr;
	socklen_t addrlen;
	int pid;

	/* First call to socket() function */
	sockfd = socket(AF_INET, SOCK_STREAM, 0);

	if (sockfd < 0) {
		perror ("ERROR opening socket");
		exit (1);
	}

	int enable = 1;
	if (setsockopt (sockfd, SOL_SOCKET, SO_REUSEADDR, &enable, sizeof(int)) == -1) {
	    perror("Setsockopt");
	    exit(1);
	}

	/* Initialize socket structure */
	bzero((char*) &serv_addr, sizeof(serv_addr));
	portno = DEFAULT_SDU_SOCKET_NUMBER;

	serv_addr.sin_family = AF_INET;
	serv_addr.sin_addr.s_addr = INADDR_ANY;
	serv_addr.sin_port = htons (portno);

	/* Now bind the host address using bind() */
	if (bind(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr))) {
		perror ("ERROR on binding");
		exit (1);
	}

	/* Now start listening for the clients, here process will
	 * go in sleep mode and will wait for the incoming connection
	 */
	/* Prepare to accept connections on socket FD.
	   N connection requests will be queued before further requests are refused.
	   Returns 0 on success, -1 for errors.  */
	printf ("Listening port %d\n", portno);
	listen(sockfd, 5);  /* The traditional value for listen()’s backlog parameter is 5. */
						/* SOMAXCONN 128 defined in sys/socket.h */
	addrlen = sizeof(cli_addr);


	/* Handle multiple connections */
	while (1) {
		/* Accept actual connection from the client */
		newsockfd = accept(sockfd, (struct sockaddr *) &cli_addr, &addrlen);

		printf ("ACCEPT %d\n", newsockfd);

		if (newsockfd < 0) {
			perror ("ERR on accept");
			exit (1);
		}
#define MULTIPLE_CONNECTION 1
#if MULTIPLE_CONNECTION
		/* Create child process */
		pid = fork();

		if (pid < 0) {
			perror ("ERROR on fork");
			exit (1);
		}
		else if (pid == 0) { /* This is the client process */
			close (sockfd); /* close server socket */
#endif
			sdu_cmds_processing (newsockfd); /* talk to client by newsockfd */
#if MULTIPLE_CONNECTION
			exit (0);
		}
		else { /* This is the parent process */
#endif
			DEBUG_log ("PARENT: fork psid %d\n", pid);
			close (newsockfd); /* close client socket */
			printf ("close client socket\n");
#if MULTIPLE_CONNECTION
		}
#endif
	}
	printf ("Bye\n");
	return 0;
}