[Ccrtp-devel] multicast problem and possible fix

[Luuk van Dijk]

Like others reported on this list I could not get my own application,
nor demo/rtplisten.cpp to work with multicast/IPv4

I replaced InetHostAddress with InetMCastAddress in rtplisten.cpp, and
saw in netstat, that an UDP socket was listened on with the multicast
address, however, netstat -g did not report group membership.

tracing the ancient Multicast-HOWTO I found that joining a multicast
group you have to give the unicast ip address of the interface you want
to join to the multicast group.   strace-ing rtplisten I saw the join
group return 'no such address'.  to cut a long story short:

diff -u ccrtp-1.0.1/src/ccrtp/rtp.h.orig ccrtp-1.0.1/src/ccrtp/rtp.h is
attached 

This is the shortest patch that makes the modified rtplisten work, and
netstat -g report membership.  As far as I understand, "0.0.0.0"
instructs the kernel to worry about finding a physical interface for
multicast reception. 

Thanks everyone for all your work on ccrtp.

        Luuk van Dijk

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