96 lines
3.2 KiB
C
96 lines
3.2 KiB
C
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/* This file is part of the sample code and exercises
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* used by the class "Advanced Programming in the UNIX
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* Environment" taught by Jan Schaumann
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* <jschauma@netmeister.org> at Stevens Institute of
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* Technology.
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*
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* https://stevens.netmeister.org/631/
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*/
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/* $NetBSD: dgramread.c,v 1.3 2003/08/07 10:30:50 agc Exp $
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*
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* Copyright (c) 1986, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)dgramread.c 8.1 (Berkeley) 6/8/93
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*/
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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/*
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* In the included file <netinet/in.h> a sockaddr_in is defined as follows:
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* struct sockaddr_in {
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* short sin_family;
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* u_short sin_port;
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* struct in_addr sin_addr;
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* char sin_zero[8];
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* };
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*
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* This program creates a datagram socket, binds a name to it, then reads
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* from the socket.
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*/
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int main()
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{
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int sock;
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socklen_t length;
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struct sockaddr_in name;
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char buf[BUFSIZ];
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memset(&name, 0, sizeof(name));
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if ((sock = socket(PF_INET, SOCK_DGRAM, 0)) < 0) {
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perror("opening datagram socket");
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exit(EXIT_FAILURE);
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}
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name.sin_family = PF_INET;
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name.sin_addr.s_addr = INADDR_ANY;
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name.sin_port = 0;
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if (bind(sock, (struct sockaddr *)&name, sizeof(name)) < 0) {
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perror("binding datagram socket");
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exit(EXIT_FAILURE);
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}
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/* Find assigned port value and print it out. */
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length = sizeof(name);
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if (getsockname(sock, (struct sockaddr *)&name, &length) < 0) {
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perror("getting socket name");
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exit(EXIT_FAILURE);
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}
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(void)printf("Socket has port #%d\n", ntohs(name.sin_port));
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if (read(sock, buf, BUFSIZ) < 0)
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perror("receiving datagram packet");
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(void)printf("-->%s\n", buf);
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(void)close(sock);
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return EXIT_SUCCESS;
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}
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