fix bug zmq4.1.x PUB msg to ZMTP 1.0 SUB svr

src/stream_engine.cpp

@@ -726,10 +726,19 @@ int zmq::stream_engine_t::process_identity_msg (msg_t *msg_)
         errno_assert (rc == 0);
     }
 
-    if (subscription_required)
-        process_msg = &stream_engine_t::write_subscription_msg;
-    else
-        process_msg = &stream_engine_t::push_msg_to_session;
+    if (subscription_required) {
+        msg_t subscription;
+
+        //  Inject the subscription message, so that also
+        //  ZMQ 2.x peers receive published messages.
+        int rc = subscription.init_size (1);
+        errno_assert (rc == 0);
+        *(unsigned char*) subscription.data () = 1;
+        rc = session->push_msg (&subscription);
+        errno_assert (rc == 0);
+    }
+
+    process_msg = &stream_engine_t::push_msg_to_session;
 
     return 0;
 }
@@ -905,23 +914,6 @@ int zmq::stream_engine_t::push_one_then_decode_and_push (msg_t *msg_)
     return rc;
 }
 
-int zmq::stream_engine_t::write_subscription_msg (msg_t *msg_)
-{
-    msg_t subscription;
-
-    //  Inject the subscription message, so that also
-    //  ZMQ 2.x peers receive published messages.
-    int rc = subscription.init_size (1);
-    errno_assert (rc == 0);
-    *(unsigned char*) subscription.data () = 1;
-    rc = session->push_msg (&subscription);
-    if (rc == -1)
-       return -1;
-
-    process_msg = &stream_engine_t::push_msg_to_session;
-    return push_msg_to_session (msg_);
-}
-
 void zmq::stream_engine_t::error (error_reason_t reason)
 {
     if (options.raw_sock) {

src/stream_engine.hpp

@@ -118,8 +118,6 @@ namespace zmq
 
         void mechanism_ready ();
 
-        int write_subscription_msg (msg_t *msg_);
-
         size_t add_property (unsigned char *ptr,
             const char *name, const void *value, size_t value_len);