\" Copyright (c) 1986 Regents of the University of California.
\" All rights reserved. The Berkeley software License Agreement
\" specifies the terms and conditions for redistribution.
\"
\" @(#)dgramread.c 6.3 (Berkeley) 5/8/86
\"
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <stdio.h>
/*
* In the included file <netinet/in.h> a sockaddr_in is defined as follows:
* struct sockaddr_in {
* short sin_family;
* u_short sin_port;
* struct in_addr sin_addr;
* char sin_zero[8];
* };
*
* This program creates a datagram socket, binds a name to it, then reads
* from the socket.
*/
main()
{
int sock, length;
struct sockaddr_in name;
char buf[1024];
/* Create socket from which to read. */
sock = socket(AF_INET, SOCK_DGRAM, 0);
if (sock < 0) {
perror("opening datagram socket");
exit(1);
}
/* Create name with wildcards. */
name.sin_family = AF_INET;
name.sin_addr.s_addr = INADDR_ANY;
name.sin_port = 0;
if (bind(sock, &name, sizeof(name))) {
perror("binding datagram socket");
exit(1);
}
/* Find assigned port value and print it out. */
length = sizeof(name);
if (getsockname(sock, &name, &length)) {
perror("getting socket name");
exit(1);
}
printf("Socket has port #%d\en", ntohs(name.sin_port));
/* Read from the socket */
if (read(sock, buf, 1024) < 0)
perror("receiving datagram packet");
printf("-->%s\en", buf);
close(sock);
}
