Fix issue #406

When a peer reconnects, the router socket receives an identity
message containing this peer id. When this happens, the current
implementation crashes.

This patch makes a router socket to silently ignore all identity
messages coming from reconnected peers.

src/msg.cpp

@@ -232,6 +232,11 @@ void zmq::msg_t::reset_flags (unsigned char flags_)
     u.base.flags &= ~flags_;
 }
 
+bool zmq::msg_t::is_identity () const
+{
+    return (u.base.flags & identity) == identity;
+}
+
 bool zmq::msg_t::is_delimiter ()
 {
     return u.base.type == type_delimiter;

src/msg.hpp

@@ -69,6 +69,7 @@ namespace zmq
         unsigned char flags ();
         void set_flags (unsigned char flags_);
         void reset_flags (unsigned char flags_);
+        bool is_identity () const;
         bool is_delimiter ();
         bool is_vsm ();
 

src/router.cpp

@@ -211,13 +211,17 @@ int zmq::router_t::xrecv (msg_t *msg_, int flags_)
 
     pipe_t *pipe = NULL;
     int rc = fq.recvpipe (msg_, &pipe);
-    if (rc != 0) {
-        errno = EAGAIN;
+
+    //  It's possible that we receive peer's identity. That happens
+    //  after reconnection. The current implementation assumes that
+    //  the peer always uses the same identity.
+    //  TODO: handle the situation when the peer changes its identity.
+    while (rc == 0 && msg_->is_identity ())
+        rc = fq.recvpipe (msg_, &pipe);
+
+    if (rc != 0)
         return -1;
-    }
 
-    //  Identity is not expected
-    zmq_assert ((msg_->flags () & msg_t::identity) == 0);
     zmq_assert (pipe != NULL);
 
     //  If we are in the middle of reading a message, just return the next part.
@@ -267,11 +271,18 @@ bool zmq::router_t::xhas_in ()
     //  The message, if read, is kept in the pre-fetch buffer.
     pipe_t *pipe = NULL;
     int rc = fq.recvpipe (&prefetched_msg, &pipe);
+
+    //  It's possible that we receive peer's identity. That happens
+    //  after reconnection. The current implementation assumes that
+    //  the peer always uses the same identity.
+    //  TODO: handle the situation when the peer changes its identity.
+    while (rc == 0 && prefetched_msg.is_identity ())
+        rc = fq.recvpipe (&prefetched_msg, &pipe);
+
     if (rc != 0)
         return false;
 
-    //  Identity is not expected
-    zmq_assert ((prefetched_msg.flags () & msg_t::identity) == 0);
+    zmq_assert (pipe != NULL);
 
     blob_t identity = pipe->get_identity ();
     rc = prefetched_id.init_size (identity.size ());