IPv4 TCP Server Code Fragment

struct sockaddr_in6 peeraddr_in6;       /* for peer socket address */

sp = getservbyname ("example", "tcp");        if (sp == NULL) {
   fprintf(stderr, "%s: example not found in /etc/services\n",argv[0]);
                exit(1);
        }
        myaddr_in.sin_port = sp->s_port;
 
                /* Create the listen socket. */
        ls = socket (AF_INET, SOCK_STREAM, 0);
        if (ls == -1) {
                perror(argv[0]);
            fprintf(stderr, "%s: unable to create socket\n", argv[0]);
                exit(1);
        }
                /* Bind the listen address to the socket. */
        if (bind(ls, &myaddr_in, sizeof(struct sockaddr_in)) == -1) {
                perror(argv[0]);
             fprintf(stderr, "%s: unable to bind address\n", argv[0]);
                exit(1);
        }
                /* Initiate the listen on the socket so remote users
                 * can connect.  The listen backlog is set to 5, which
                 * is within the supported range of 1 to 20.
                 */
        if (listen(ls, 5) == -1) {
          perror(argv[0]);
          fprintf(stderr, "%s: unable to listen on socket\n", argv[0]);
                exit(1);
        }