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

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2011-09-29 09:32:27 -06:00
/* multicast_client.c
* Adopted from tmouse's client/server example code
* found at http://cboard.cprogramming.com/showthread.php?t=67469
*/
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include <stdio.h> /* for printf() and fprintf() */
#include <stdlib.h> /* for atoi() and exit() */
#include <string.h> /* for memset() */
#include <time.h> /* for timestamps */
#include <unistd.h>
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: Port */
struct addrinfo * multicastAddr = {0}; /* Multicast Address */
struct addrinfo * localAddr; /* Local address to bind to */
struct addrinfo hints = { 0 }; /* Hints for name lookup */
if ( argc != 3 )
{
fprintf(stderr,"Usage: %s <Multicast IP> <Multicast Port>\n", argv[0]);
exit(10);
}
multicastIP = argv[1]; /* First arg: Multicast IP address */
multicastPort = argv[2]; /* Second arg: Multicast port */
/* Resolve the multicast group address */
hints.ai_family = PF_INET6;
hints.ai_flags = AI_NUMERICHOST;
if ( getaddrinfo(multicastIP, NULL, &hints, &multicastAddr) != 0 ) DieWithError("getaddrinfo() failed");
/* Get a local address with the same family as our multicast group */
hints.ai_family = multicastAddr->ai_family;
hints.ai_socktype = SOCK_DGRAM;
hints.ai_flags = AI_PASSIVE; /* Return an address we can bind to */
if ( getaddrinfo(NULL, multicastPort, &hints, &localAddr) != 0 )
{
DieWithError("getaddrinfo() failed");
}
/* Create socket for receiving datagrams */
if ( (sock = socket(localAddr->ai_family, localAddr->ai_socktype, 0)) == -1 )
{
DieWithError("socket() failed");
}
const int trueValue = 1;
setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, (const void *) &trueValue, sizeof(trueValue));
#ifdef __APPLE__
setsockopt(sock, SOL_SOCKET, SO_REUSEPORT, (const void *) &trueValue, sizeof(trueValue));
#endif
/* Bind to the multicast port */
if ( bind(sock, localAddr->ai_addr, localAddr->ai_addrlen) != 0 )
{
DieWithError("bind() failed");
}
/* Join the multicast group. */
if ((multicastAddr->ai_family == PF_INET6)&&(multicastAddr->ai_addrlen == sizeof(struct sockaddr_in6)))
{
struct sockaddr_in6 *addr = (struct sockaddr_in6 *)(multicastAddr->ai_addr);
struct ipv6_mreq multicastRequest; /* Multicast address join structure */
/* Specify the multicast group */
memcpy(&multicastRequest.ipv6mr_multiaddr, &((struct sockaddr_in6*)(multicastAddr->ai_addr))->sin6_addr, sizeof(multicastRequest.ipv6mr_multiaddr));
printf("scope_id: %d\n", addr->sin6_scope_id);
/* Accept multicast from any interface */
multicastRequest.ipv6mr_interface = addr->sin6_scope_id;
/* Join the multicast address */
if ( setsockopt(sock, IPPROTO_IPV6, IPV6_JOIN_GROUP, (char*) &multicastRequest, sizeof(multicastRequest)) != 0 ) DieWithError("setsockopt(IPV6_JOIN_GROUP) failed");
}
else DieWithError("Not IPv6");
freeaddrinfo(localAddr);
freeaddrinfo(multicastAddr);
for (;;) /* Run forever */
{
char recvString[500]; /* Buffer for received string */
int recvStringLen; /* Length of received string */
/* Receive a single datagram from the server */
if ((recvStringLen = recvfrom(sock, recvString, sizeof(recvString) - 1, 0, NULL, 0)) < 0) DieWithError("recvfrom() failed");
recvString[recvStringLen] = '\0';
/* Print the received string */
printf("Received string [%s]\n", recvString);
}
/* NOT REACHED */
close(sock);
exit(EXIT_SUCCESS);
}