refactored ZMQ_ROUTER_ANNOUNCE_SELF code. renamed it to ZMQ_PROBE_NEW_PEERS.

implement it for DEALER tocket.
+documentation

doc/zmq_setsockopt.txt

@@ -421,21 +421,19 @@ Default value:: 0
 Applicable socket types:: ZMQ_ROUTER
 
 
-ZMQ_PROBE: automatically send empty packet to every established connection
+ZMQ_PROBE_NEW_PEERS: automatically send empty packet to every established connection
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-Sets the compatible sockets behavior to automatically send an empty packet
+Sets the 'ROUTER' & 'DEALER' sockets behavior to automatically send an empty packet
 to any new connection made (or accepted) by socket. It could help sockets to
-auto discovery them-self. It especially important in 'ROUTER' <-> 'ROUTER' connections
+auto discovery themself. It especially important in 'ROUTER' <-> 'ROUTER' connections
 where it solves 'who will write first' problems.
-NOTE: Don't set this options for sockets working with ZMQ_REP, ZMQ_REQ sockets.
-It will interfere with their strict synchronous logic and framing.
 
 [horizontal]
 Option value type:: int
 Option value unit:: 0, 1
 Default value:: 0
-Applicable socket types:: ZMQ_ROUTER, ZMQ_DEALER, ZMQ_REP, ZMQ_REQ
+Applicable socket types:: ZMQ_ROUTER, ZMQ_DEALER
 
 
 ZMQ_XPUB_VERBOSE: provide all subscription messages on XPUB sockets

src/dealer.cpp

@@ -40,14 +40,14 @@ void zmq::dealer_t::xattach_pipe (pipe_t *pipe_, bool icanhasall_)
     zmq_assert (pipe_);
 
     if (probe_new_peers) {
-        int rc;
+        int rc, ok;
         msg_t probe_msg_;
 
         rc = probe_msg_.init ();
         errno_assert (rc == 0);
 
-        rc = pipe_->write (&probe_msg_);
-        zmq_assert (rc);
+        ok = pipe_->write (&probe_msg_);
+        zmq_assert (ok);
         pipe_->flush ();
 
         rc = probe_msg_.close ();

src/router.cpp

@@ -398,12 +398,15 @@ bool zmq::router_t::identify_peer (pipe_t *pipe_)
         rc = probe_msg_.init ();
         errno_assert (rc == 0);
 
-        rc = pipe_->write (&probe_msg_);
-        zmq_assert (rc);
+        ok = pipe_->write (&probe_msg_);
         pipe_->flush ();
 
         rc = probe_msg_.close ();
         errno_assert (rc == 0);
+
+        //  Ignore not probed peers
+        if (!ok)
+            return false;
     }
 
     return true;