PROBLEM: setsockopt & IP_ADD_MEMBERSHIP

QNX DEVELOPERS General Programming
1

Hi,

I’ve got a problem with this piece of code :frowning: (reduced) under QNX 6.3:

[color=darkred]sd = socket (PF_INET, SOCK_DGRAM, 0);
if (sd >= 0) {
mreq.imr_interface.s_addr = INADDR_ANY;
if(setsockopt (sd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq, sizeof (mreq)) !=0) {
//here goes error errno=EINVAL :question:
}
…
}

I looked in internet for something about this problem, but it looks I’m not alone with this :confused: .
I’ve tried many possibe combinations op IP’s in structure mreq but everytime it fail on EINVAL!
Is there problem in network interface of setsockopt?
Can anybody help me? Thanx.

2

What group are you joining ?

You are not setting mreq.imr_multiaddr.s_addr in the snippet your provide.

3

my “test” source:

[color=darkred]//here are combinations I’ve tested and they don’t work

//mreq.imr_interface.s_addr = 0x0;
//mreq.imr_multiaddr.s_addr = 0x0;

//mreq.imr_interface.s_addr = inet_addr(“192.168.10.177”);
//mreq.imr_multiaddr.s_addr = inet_addr(“192.168.10.255”);

//mreq.imr_interface.s_addr = htonl(INADDR_ANY);
//mreq.imr_multiaddr.s_addr = inet_addr(“192.168.10.255”);

mreq.imr_interface.s_addr = inet_addr(“192.168.10.177”);
mreq.imr_multiaddr.s_addr = htonl(INADDR_ANY);

printf(“IFace %s\r\n”, inet_ntoa(mreq.imr_interface));
printf(“BCAST %s\r\n”, inet_ntoa(mreq.imr_multiaddr));

if (setsockopt(fd, IPPROTO_UDP, IP_ADD_MEMBERSHIP, (char *) &mreq, sizeof(mreq)) != 0) {
//broadcast receiving failed
errvalue = errno;
printf(errstr, “Warn: Err BROADCAST listening (%d: %s)”, errvalue, strerror( errvalue ));
}

ifconfig returns:

[color=darkblue]lo0: flags=8009<UP,LOOPBACK,MULTICAST> mtu 33212
capabilities=7<IP4CSUM,TCP4CSUM,UDP4CSUM>
enabled=0<>
inet 127.0.0.1 netmask 0xff000000
en0: flags=8a43<UP,BROADCAST,RUNNING,ALLMULTI,SIMPLEX,MULTICAST> mtu 1500
capabilities=7<IP4CSUM,TCP4CSUM,UDP4CSUM>
enabled=0<>
address: 00:04:75:e4:84:63
inet 192.168.10.177 netmask 0xffffff00 broadcast 192.168.10.255
en1: flags=8842<BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
capabilities=7<IP4CSUM,TCP4CSUM,UDP4CSUM>
enabled=0<>
address: 00:04:75:e4:2e:b0

4

GOTTA IT

I must have IP from D class (for example 224.1.1.1), then it works…
mreq.imr_interface.s_addr = htonl(INADDR_ANY);
mreq.imr_multiaddr.s_addr = inet_addr(“224.1.1.255”);