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From Lorenz Breu <>
Subject [APR/JNI] send from specific interface
Date Tue, 11 Nov 2008 14:45:48 GMT
hi guys

can somebody give me a hint on how to send a udp message from a specific
port using the jni (or directly the apr) code? i am trying the following:

long handle = Socket.create(Socket.APR_INET, Socket.SOCK_DGRAM,
Socket.APR_PROTO_UDP, pool);
Socket.optSet(handle, Socket.APR_SO_NONBLOCK, 1);
Socket.timeoutSet(handle, 0);
InetSocketAddress la = (InetSocketAddress) localAddress;
long sa;
if (la.getAddress() == null) {
    sa =, Socket.APR_INET,
la.getPort(), 0, pool);
} else {
    sa =, Socket.APR_INET,
la.getPort(), 0, pool);
Multicast.hops(handle, ttl);
Socket.bind(handle, sa);
Socket.connect(handle, remoteAddress);

If I leave out the bind part and just connect the socket to the remote
address (in this case also on localhost) it works fine, everything works
fine, however as soon as i do the bind() first followed by the
connect(), it looks like the message is no longer received by the
receiver (on the same machine)... any caveats i am missing? wireshark
lists the udp packet, even with a  "good" source port if i set the local
address port to 0, so it may be sent, but then why is it not received if
i send to the same address as before without the bind()?? or is it not
sent after all? but then why would wireshark list the datagram?

does anybody have an idea, where i could be going wrong? should i ask
such questions on the users list?


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