The previous code to block the socket from receiving on that pipe during a…

The previous code to block the socket from receiving on that pipe during a disconnect was vulnerable to a race condition. This code calls with the terminate functions of both ends of the pipe - I believe this should be safer. This required storing a pointer to the socket end of the pipe

src/session_base.cpp

@@ -308,6 +308,9 @@ void zmq::session_base_t::process_attach (i_engine *engine_)
 
         //  Ask socket to plug into the remote end of the pipe.
         send_bind (socket, pipes [1]);
+
+        //  Store the outpipe for disconnect situations
+        outpipe = pipes [1];
     }
 
     //  Plug in the engine.
@@ -411,8 +414,7 @@ void zmq::session_base_t::detached ()
     if (pipe && options.delay_attach_on_connect == 1
         && addr->protocol != "pgm" && addr->protocol != "epgm") {
         pipe->terminate (false);
-        socket->terminated (pipe);
-        pipe = NULL;
+        outpipe->terminate (false);
     }
 }
 

src/session_base.hpp

@@ -103,6 +103,9 @@ namespace zmq
 
         //  Pipe connecting the session to its socket.
         zmq::pipe_t *pipe;
+        
+        //  Socket end of the pipe, for delay attach scenario
+        zmq::pipe_t *outpipe;
 
         //  This flag is true if the remainder of the message being processed
         //  is still in the in pipe.