corrections and additions

[unix-history] / usr / src / share / doc / psd / 20.ipctut / strchkread.c

.\" Copyright (c) 1986 Regents of the University of California.
.\" All rights reserved.  The Berkeley software License Agreement
.\" specifies the terms and conditions for redistribution.
.\"
.\"     @(#)strchkread.c        6.2 (Berkeley) %G%
.\"
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <netinet/in.h>
#include <netdb.h>
#include <stdio.h>
#define TRUE 1

/*
* This program uses select() to check that someone is trying to connect
* before calling accept(). 
*/

main()
{
       int sock, length;
       struct sockaddr_in server;
       int msgsock;
       char buf[1024];
       int rval;
       fd_set ready;
       struct timeval to;

       /* Create socket */
       sock = socket(AF_INET, SOCK_STREAM, 0);
       if (sock < 0) {
               perror("opening stream socket");
               exit(1);
       }
       /* Name socket using wildcards */
       server.sin_family = AF_INET;
       server.sin_addr.s_addr = INADDR_ANY;
       server.sin_port = 0;
       if (bind(sock, &server, sizeof(server))) {
               perror("binding stream socket");
               exit(1);
       }
       /* Find out assigned port number and print it out */
       length = sizeof(server);
       if (getsockname(sock, &server, &length)) {
               perror("getting socket name");
               exit(1);
       }
       printf("Socket has port #%d\en", ntohs(server.sin_port));

       /* Start accepting connections */
       listen(sock, 5);
       do {
               FD_ZERO(&ready);
               FD_SET(sock, &ready);
               to.tv_sec = 5;
               if (select(sock + 1, &ready, 0, 0, &to) < 0) {
                       perror("select");
                       continue;
               }
               if (FD_ISSET(sock, &ready)) {
                       msgsock = accept(sock, (struct sockaddr *)0, (int *)0);
                       if (msgsock == -1)
                               perror("accept");
                       else do {
                               bzero(buf, sizeof(buf));
                               if ((rval = read(msgsock, buf, 1024)) < 0)
                                       perror("reading stream message");
                               else if (rval == 0)
                                       printf("Ending connection\en");
                               else
                                       printf("-->%s\en", buf);
                       } while (rval > 0);
                       close(msgsock);
               } else
                       printf("Do something else\en");
       } while (TRUE);
}