Add 'Peer-Address' property to connection metadata

Allows non-C/C++ based clients easy access to the peer's IP address via
zmq_msg_gets(&msg, "Peer-Address") instead of zmq_msg_get(&msg, ZMQ_SRCFD)
followed by calls to getpeername and getnameinfo

.gitignore

@@ -137,3 +137,4 @@ zeromq-*.tar.gz
 zeromq-*.zip
 core
 build
+test-suite.log

doc/zmq_msg_gets.txt

@@ -28,6 +28,7 @@ function:
     Socket-Type
     Identity
     Resource
+    Peer-Address
 
 Other properties may be defined based on the underlying security, see ZAP
 auththenticated connection sample below.

src/stream_engine.cpp

@@ -806,6 +806,11 @@ void zmq::stream_engine_t::mechanism_ready ()
     properties_t properties;
     properties_t::const_iterator it;
 
+    //  If we have a peer_address, add it to metadata
+    if (!peer_address.empty()) {
+        properties.insert(std::make_pair("Peer-Address", peer_address));
+    }
+
     //  Add ZAP properties.
     const properties_t& zap_properties = mechanism->get_zap_properties ();
     it = zap_properties.begin ();

tests/test_metadata.cpp

@@ -100,6 +100,8 @@ int main (void)
     assert (streq (zmq_msg_gets (&msg, "Hello"), "World"));
     assert (streq (zmq_msg_gets (&msg, "Socket-Type"), "DEALER"));
     assert (streq (zmq_msg_gets (&msg, "User-Id"), "anonymous"));
+    assert (streq (zmq_msg_gets (&msg, "Peer-Address"), "127.0.0.1"));
+
     assert (zmq_msg_gets (&msg, "No Such") == NULL);
     assert (zmq_errno () == EINVAL);
     zmq_msg_close (&msg);