Problem: proxy leaks one message payload (0..n bytes) on close.

src/proxy.cpp

@@ -143,7 +143,7 @@ int zmq::proxy (
         //  Wait while there are either requests or replies to process.
         rc = zmq_poll (&items [0], qt_poll_items, -1);
         if (unlikely (rc < 0))
-            return -1;
+            return close_and_return (&msg, -1);
 
         //  Get the pollout separately because when combining this with pollin it maxes the CPU
         //  because pollout shall most of the time return directly.
@@ -151,7 +151,7 @@ int zmq::proxy (
         if (frontend_ != backend_) {
             rc = zmq_poll (&itemsout [0], 2, 0);
             if (unlikely (rc < 0)) {
-                return -1;
+                return close_and_return (&msg, -1);
             }
         }
 
@@ -159,17 +159,17 @@ int zmq::proxy (
         if (control_ && items [2].revents & ZMQ_POLLIN) {
             rc = control_->recv (&msg, 0);
             if (unlikely (rc < 0))
-                return -1;
+                return close_and_return (&msg, -1);
 
             moresz = sizeof more;
             rc = control_->getsockopt (ZMQ_RCVMORE, &more, &moresz);
             if (unlikely (rc < 0) || more)
-                return -1;
+                return close_and_return (&msg, -1);
 
             //  Copy message to capture socket if any
-            rc = capture(capture_, msg);
+            rc = capture (capture_, msg);
             if (unlikely (rc < 0))
-                return -1;
+                return close_and_return (&msg, -1);
 
             if (msg.size () == 5 && memcmp (msg.data (), "PAUSE", 5) == 0)
                 state = paused;
@@ -180,7 +180,7 @@ int zmq::proxy (
             if (msg.size () == 9 && memcmp (msg.data (), "TERMINATE", 9) == 0)
                 state = terminated;
             else {
-                //  This is an API error, we should assert
+                //  This is an API error, so we assert
                 puts ("E: invalid command sent to proxy");
                 zmq_assert (false);
             }
@@ -189,19 +189,20 @@ int zmq::proxy (
         if (state == active
         &&  items [0].revents & ZMQ_POLLIN
         &&  (frontend_ == backend_ || itemsout [1].revents & ZMQ_POLLOUT)) {
-            rc = forward(frontend_, backend_, capture_,msg);
+            rc = forward (frontend_, backend_, capture_, msg);
             if (unlikely (rc < 0))
-                return -1;
+                return close_and_return (&msg, -1);
         }
         //  Process a reply
         if (state == active
         &&  frontend_ != backend_
         &&  items [1].revents & ZMQ_POLLIN
         &&  itemsout [0].revents & ZMQ_POLLOUT) {
-            rc = forward(backend_, frontend_, capture_,msg);
+            rc = forward (backend_, frontend_, capture_, msg);
             if (unlikely (rc < 0))
-                return -1;
+                return close_and_return (&msg, -1);
         }
     }
-    return 0;
+
+    return close_and_return (&msg, 0);
 }