Problem: CLIENT and SERVER don't check SNDMORE

These sockets don't handle multipart data, so if callers send it,
they drop frames, and things break silently.

Solution: if the caller tries to use ZMQ_SNDMORE, return -1 and
set errno to EINVAL.

doc/zmq_msg_send.txt

@@ -67,6 +67,8 @@ ERRORS
 Non-blocking mode was requested and the message cannot be sent at the moment.
 *ENOTSUP*::
 The _zmq_msg_send()_ operation is not supported by this socket type.
+*EINVAL*::
+The sender tried to send multipart data, which the socket type does not allow.
 *EFSM*::
 The _zmq_msg_send()_ operation cannot be performed on this socket at the moment
 due to the socket not being in the appropriate state.  This error may occur with

doc/zmq_send.txt

@@ -58,6 +58,8 @@ ERRORS
 Non-blocking mode was requested and the message cannot be sent at the moment.
 *ENOTSUP*::
 The _zmq_send()_ operation is not supported by this socket type.
+*EINVAL*::
+The sender tried to send multipart data, which the socket type does not allow.
 *EFSM*::
 The _zmq_send()_ operation cannot be performed on this socket at the moment
 due to the socket not being in the appropriate state.  This error may occur with

doc/zmq_sendmsg.txt

@@ -63,6 +63,8 @@ ERRORS
 Non-blocking mode was requested and the message cannot be sent at the moment.
 *ENOTSUP*::
 The _zmq_sendmsg()_ operation is not supported by this socket type.
+*EINVAL*::
+The sender tried to send multipart data, which the socket type does not allow.
 *EFSM*::
 The _zmq_sendmsg()_ operation cannot be performed on this socket at the moment
 due to the socket not being in the appropriate state.  This error may occur with

src/client.cpp

@@ -54,6 +54,11 @@ void zmq::client_t::xattach_pipe (pipe_t *pipe_, bool subscribe_to_all_)
 
 int zmq::client_t::xsend (msg_t *msg_)
 {
+    //  CLIENT sockets do not allow multipart data (ZMQ_SNDMORE)
+    if (msg_->flags () & msg_t::more) {
+        errno = EINVAL;
+        return -1;
+    }
     return lb.sendpipe (msg_, NULL);
 }
 

src/server.cpp

@@ -93,6 +93,11 @@ void zmq::server_t::xwrite_activated (pipe_t *pipe_)
 
 int zmq::server_t::xsend (msg_t *msg_)
 {
+    //  SERVER sockets do not allow multipart data (ZMQ_SNDMORE)
+    if (msg_->flags () & msg_t::more) {
+        errno = EINVAL;
+        return -1;
+    }
     //  Find the pipe associated with the routing stored in the message.
     uint32_t routing_id = msg_->get_routing_id ();
     outpipes_t::iterator it = outpipes.find (routing_id);
@@ -108,7 +113,6 @@ int zmq::server_t::xsend (msg_t *msg_)
         errno = EHOSTUNREACH;
         return -1;
     }
-
     bool ok = it->second.pipe->write (msg_);
     if (unlikely (!ok)) {
         // Message failed to send - we must close it ourselves.
@@ -118,7 +122,6 @@ int zmq::server_t::xsend (msg_t *msg_)
     else
         it->second.pipe->flush ();
 
-
     //  Detach the message from the data buffer.
     int rc = msg_->init ();
     errno_assert (rc == 0);

src/socket_base.cpp

@@ -96,7 +96,7 @@
     if (thread_safe) \
         sync.lock();
 
-#define EXIT_MUTEX() \
+#define EXIT_MUTEX(); \
     if (thread_safe) \
         sync.unlock();
 
@@ -1047,7 +1047,7 @@ int zmq::socket_base_t::send (msg_t *msg_, int flags_)
 
     msg_->reset_metadata ();
 
-    //  Try to send the message.
+    //  Try to send the message using method in each socket class
     rc = xsend (msg_);
     if (rc == 0) {
         EXIT_MUTEX ();
@@ -1426,7 +1426,6 @@ void zmq::socket_base_t::in_event ()
     //  of the reaper thread. Process any commands from other threads/sockets
     //  that may be available at the moment. Ultimately, the socket will
     //  be destroyed.
-
     ENTER_MUTEX ();
 
     //  If the socket is thread safe we need to unsignal the reaper signaler

tests/test_client_server.cpp

@@ -51,11 +51,15 @@ int main (void)
     char *data = (char *) zmq_msg_data (&msg);
     data [0] = 1;
 
+    rc = zmq_msg_send (&msg, client, ZMQ_SNDMORE);
+    assert (rc == -1);
+
     rc = zmq_msg_send (&msg, client, 0);
     assert (rc == 1);
 
     rc = zmq_msg_init (&msg);
     assert (rc == 0);
+
     rc = zmq_msg_recv (&msg, server, 0);
     assert (rc == 1);
 
@@ -74,6 +78,9 @@ int main (void)
     rc = zmq_msg_set_routing_id (&msg, routing_id);
     assert (rc == 0);
 
+    rc = zmq_msg_send (&msg, server, ZMQ_SNDMORE);
+    assert (rc == -1);
+
     rc = zmq_msg_send (&msg, server, 0);
     assert (rc == 1);