Get TCP address information in ZeroMQ

0MQ doesn't provide the address of peers, for a number of reasons. It's also not that useful since what you really want is the endpoint to receive connections on, not the address the connection was made on.

What I usually do, and it's elegant enough, is pass bind a service to an ephemeral port, get a full connection endpoint ("tcp://ipaddress:port") and send that string in some way, either broadcast to peers, to a central registry, etc. along with my service name. Then, peers who want to connect back can take the service name, look up to find my endpoint, and connect back to me.

In ZMQ 4.x, you may get the string property "Peer-Address" or the "Identity" property. http://api.zeromq.org/4-2:zmq-msg-gets

The Identity is set in the other peer before connect(). http://api.zeromq.org/4-2:zmq-setsockopt#toc20

For example,

const char *identityString = "identity";
zmq::context_t context(1);
zmq::socket_t socket(context, ZMQ_REQ);
socket.setsockopt(ZMQ_IDENTITY, identityString, strlen(identityString));
socket.connect("tcp://127.0.0.1:5555");

Then the other side:

while(1)
{
    zmq::message_t request;
    if (socket.recv(&request, ZMQ_NOBLOCK))
    {
        const char* identity = request.gets("Identity");
        const char* peerAddress = request.gets("Peer-Address");
        printf("Received from %s %s\n", peerAddress, identity);
        break;
    }
}

I'm using CppZmq btw, you should be able to find the relevant calls easily.