Bind transmitted packets to the port's network interface.
Even though the MCAST_JOIN_GROUP socket option includes the interface index, this applies to the received packets only. To bind the outgoing packets to a particular interface, the IP_MULTICAST_IF option is needed. Signed-off-by: Richard Cochran <richardcochran@gmail.com>master
parent
ebd353aff6
commit
5f7facdc63
17
udp.c
17
udp.c
|
@ -113,6 +113,20 @@ static int interface_index(int fd, char *name)
|
|||
return ifreq.ifr_ifindex;
|
||||
}
|
||||
|
||||
static int mcast_bind(int fd, int index)
|
||||
{
|
||||
int err;
|
||||
struct ip_mreqn req;
|
||||
memset(&req, 0, sizeof(req));
|
||||
req.imr_ifindex = index;
|
||||
err = setsockopt(fd, IPPROTO_IP, IP_MULTICAST_IF, &req, sizeof(req));
|
||||
if (err) {
|
||||
perror("setsockopt IP_MULTICAST_IF");
|
||||
return -1;
|
||||
}
|
||||
return 0;
|
||||
}
|
||||
|
||||
static int mcast_join(int fd, int index, const struct sockaddr *grp,
|
||||
socklen_t grplen)
|
||||
{
|
||||
|
@ -169,6 +183,9 @@ static int open_socket(char *name, struct in_addr *mc_addr, short port)
|
|||
perror("mcast_join");
|
||||
goto no_option;
|
||||
}
|
||||
if (mcast_bind(fd, index)) {
|
||||
goto no_option;
|
||||
}
|
||||
return fd;
|
||||
no_option:
|
||||
close(fd);
|
||||
|
|
Loading…
Reference in New Issue