moth/packages/multicaster/src/multicaster-server.c

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2011-09-29 09:32:27 -06:00
/* multicast_server.c
* Adapted from tmouse's IPv6 client/server example code
* found at http://cboard.cprogramming.com/showthread.php?t=67469
*/
#include <stdio.h> /* for fprintf() */
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <stdlib.h> /* for atoi() and exit() */
#include <unistd.h>
#include <string.h>
static void DieWithError(const char* errorMessage)
{
fprintf(stderr, "%s\n", errorMessage);
exit(10);
}
int main(int argc, char *argv[])
{
int sock; /* Socket */
char* multicastIP; /* Arg: IP Multicast address */
char* multicastPort; /* Arg: Server port */
char* sendString; /* Arg: String to multicast */
size_t sendStringLen; /* Length of string to multicast */
struct addrinfo * multicastAddr; /* Multicast address */
struct addrinfo hints = { 0 }; /* Hints for name lookup */
if ( argc != 4 )
{
fprintf(stderr, "Usage: %s <Multicast Address> <Port> <Send String>\n", argv[0]);
exit(10);
}
multicastIP = argv[1]; /* First arg: multicast IP address */
multicastPort = argv[2]; /* Second arg: multicast port */
sendString = argv[3]; /* Third arg: String to multicast */
sendStringLen = strlen(sendString); /* Find length of sendString */
/* Resolve destination address for multicast datagrams */
hints.ai_family = PF_INET6;
hints.ai_socktype = SOCK_DGRAM;
hints.ai_flags = AI_NUMERICHOST;
if (getaddrinfo(multicastIP, multicastPort, &hints, &multicastAddr) != 0) DieWithError("getaddrinfo() failed");
/* Create socket for sending multicast datagrams */
if ((sock = socket(multicastAddr->ai_family, multicastAddr->ai_socktype, 0)) == -1) DieWithError("socket() failed");
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int hops = 5;
if (setsockopt(sock, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &hops, sizeof(hops)) != 0) DieWithError("setsockopt(MULTICAST_HOPS) failed");
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for (;;) /* Run forever */
{
int sendLen = sendto(sock, sendString, sendStringLen, 0, multicastAddr->ai_addr, multicastAddr->ai_addrlen);
if (sendLen == sendStringLen )
{
printf("Sent [%s] (%i bytes) to %s, port %s\n", sendString, sendLen, multicastIP, multicastPort);
}
else
{
DieWithError("sendto() sent a different number of bytes than expected");
}
sleep(1); /* Multicast sendString in datagram to clients every second */
}
/* NOT REACHED */
freeaddrinfo(multicastAddr);
close(sock);
return 0;
}