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#!/bin/sh
# Multicast test example by Mark Claypool, claypool at cs.wpi.edu
# https://web.cs.wpi.edu/~claypool/courses/4514-B99/samples/multicast.c
# Kernel page fault seen with WiP branch:
# https://people.freebsd.org/~pho/stress/log/kip036.txt
. ../default.cfg
dir=/tmp
odir=`pwd`
cd $dir
sed '1,/^EOF/d' < $odir/$0 > $dir/multicast.c
mycc -o multicast -Wall -Wextra -O0 -g multicast.c || exit 1
rm -f multicast.c
cd $odir
cd $dir
(
timeout -k 1s 20s ./multicast &
sleep 1
timeout -k 1s 25s ./multicast 1
) > /dev/null
wait
rm -f $dir/multicast
exit $s
EOF
/*
multicast.c
The following program sends or receives multicast packets. If invoked
with one argument, it sends a packet containing the current time to an
arbitrarily chosen multicast group and UDP port. If invoked with no
arguments, it receives and prints these packets. Start it as a sender on
just one host and as a receiver on all the other hosts
*/
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>
#include <time.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#define EXAMPLE_PORT 6000
#define EXAMPLE_GROUP "239.0.0.1"
int
main(int argc, char *argv[] __unused)
{
struct ip_mreq mreq;
struct sockaddr_in addr;
socklen_t addrlen;
int cnt, sock;
char message[50];
/* set up socket */
sock = socket(AF_INET, SOCK_DGRAM, 0);
if (sock < 0) {
perror("socket");
exit(1);
}
bzero((char *)&addr, sizeof(addr));
addr.sin_family = AF_INET;
addr.sin_addr.s_addr = htonl(INADDR_ANY);
addr.sin_port = htons(EXAMPLE_PORT);
addrlen = sizeof(addr);
if (argc > 1) {
/* send */
addr.sin_addr.s_addr = inet_addr(EXAMPLE_GROUP);
while (1) {
time_t t = time(0);
sprintf(message, "time is %-24.24s", ctime(&t));
printf("sending: %s\n", message);
cnt = sendto(sock, message, sizeof(message), 0,
(struct sockaddr *) &addr, addrlen);
if (cnt < 0) {
perror("sendto");
exit(1);
}
sleep(5);
}
} else {
/* receive */
if (bind(sock, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
perror("bind");
exit(1);
}
mreq.imr_multiaddr.s_addr = inet_addr(EXAMPLE_GROUP);
mreq.imr_interface.s_addr = htonl(INADDR_ANY);
if (setsockopt(sock, IPPROTO_IP, IP_ADD_MEMBERSHIP,
&mreq, sizeof(mreq)) < 0) {
perror("setsockopt mreq");
exit(1);
}
while (1) {
cnt = recvfrom(sock, message, sizeof(message), 0,
(struct sockaddr *) &addr, &addrlen);
if (cnt < 0) {
perror("recvfrom");
exit(1);
} else if (cnt == 0) {
break;
}
printf("%s: message = \"%s\"\n", inet_ntoa(addr.sin_addr), message);
}
}
}
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