If you say
$ strace -e bind ./testMPEG2TransportStreamer
you find that it calls bind() twice, once for 0.0.0.0:1234, and another
time for the "find my IP" hack.
Ultimately, I don't see why it needs to call bind() at all in this
program since a UDP sender is just tossing packets out onto the network.
It's not receiving anything. (Yes, I saw the "Windoze" case mentioned
in the nearby comment. Separate issue. We're on Linux.)
This causes a problem for us because we have another program -- not
based on Live555 -- which is simultaneously trying to receive packets
from a different IP on the same port number, and it gets a bind()
failure (errno = EADDRINUSE) because the Live555 program has effectively
claimed total ownership of that port number on all interfaces by asking
for 0.0.0.0.
I've tried running two instances of testMPEG2TransportStreamer on
different IPs, and apparently our network stack (Linux 2.6.18) will let
two programs bind() to 0.0.0.0:1234, but it won't let another program
bind to, say, 239.255.42.44:1234 at the same time.
We made a one-line change to Live555 (see attached patch) and it fixes
the symptom for us. It seems like a reasonable change to me, but I'm
not sure it isn't some kind of overreach.
We could instead fix this by using different port numbers *and*
different IPs for our senders and receivers. (We tried it, and it
worked.) We don't want to do that purely because separating senders and
receivers by putting them on different multicast addresses should be
enough. That make a different 5-tuple, so we should be able to keep the
same port number.
@@ -135,7 +135,7 @@
netAddressBits addr = INADDR_ANY;
#if defined(__WIN32__) || defined(_WIN32)
#else
- if (port.num() != 0 || ReceivingInterfaceAddr != INADDR_ANY) {
+ if (port.num() != 0 && ReceivingInterfaceAddr != INADDR_ANY) {
#endif
if (port.num() == 0) addr = ReceivingInterfaceAddr;
MAKE_SOCKADDR_IN(name, addr, port.num());
_______________________________________________
live-devel mailing list
live-devel@lists.live555.com
http://lists.live555.com/mailman/listinfo/live-devel
