Merge pull request #2752 from sigiesec/test-no-zap-handler

Problem: missing tests and inconsistent behaviour for ZAP corner cases

src/curve_server.cpp

@@ -390,18 +390,29 @@ int zmq::curve_server_t::process_initiate (msg_t *msg_)
     rc = crypto_box_beforenm (cn_precom, cn_client, cn_secret);
     zmq_assert (rc == 0);
 
+    if (zap_required ()) {
         //  Use ZAP protocol (RFC 27) to authenticate the user.
-    //  Note that rc will be -1 only if ZAP is not set up (Stonehouse pattern -
-    //  encryption without authentication), but if it was requested and it does
-    //  not work properly the program will abort.
         rc = session->zap_connect ();
         if (rc == 0) {
             send_zap_request (client_key);
+            state = waiting_for_zap_reply;
+
+            //  TODO actually, it is quite unlikely that we can read the ZAP 
+            //  reply already, but removing this has some strange side-effect
+            //  (probably because the pipe's in_active flag is true until a read 
+            //  is attempted)
             rc = receive_and_process_zap_reply ();
             if (rc == -1)
                 return -1;
-    } else
+        } else {
+            session->get_socket ()->event_handshake_failed_no_detail (
+              session->get_endpoint (), EFAULT);
+            return -1;
+        }
+    } else {
+        //  This supports the Stonehouse pattern (encryption without authentication).
         state = sending_ready;
+    }
 
     return parse_metadata (initiate_plaintext + crypto_box_ZEROBYTES + 128,
                            clen - crypto_box_ZEROBYTES - 128);

src/mechanism_base.cpp

@@ -63,3 +63,8 @@ void zmq::mechanism_base_t::handle_error_reason (const char *error_reason,
           session->get_endpoint (), (error_reason[0] - '0') * 100);
     }
 }
+
+bool zmq::mechanism_base_t::zap_required() const
+{
+    return !options.zap_domain.empty ();
+}

src/mechanism_base.hpp

@@ -45,6 +45,8 @@ class mechanism_base_t : public mechanism_t
     int check_basic_command_structure (msg_t *msg_);
 
     void handle_error_reason (const char *error_reason, size_t error_reason_len);
+
+    bool zap_required() const;
 };
 }
 

src/null_mechanism.cpp

@@ -48,15 +48,9 @@ zmq::null_mechanism_t::null_mechanism_t (session_base_t *session_,
     error_command_sent (false),
     ready_command_received (false),
     error_command_received (false),
-    zap_connected (false),
     zap_request_sent (false),
     zap_reply_received (false)
 {
-    //  NULL mechanism only uses ZAP if there's a domain defined
-    //  This prevents ZAP requests on naive sockets
-    if (options.zap_domain.size () > 0
-    &&  session->zap_connect () == 0)
-        zap_connected = true;
 }
 
 zmq::null_mechanism_t::~null_mechanism_t ()
@@ -69,16 +63,31 @@ int zmq::null_mechanism_t::next_handshake_command (msg_t *msg_)
         errno = EAGAIN;
         return -1;
     }
-    if (zap_connected && !zap_reply_received) {
+
+    if (zap_required() && !zap_reply_received) {
         if (zap_request_sent) {
             errno = EAGAIN;
             return -1;
         }
+        int rc = session->zap_connect();
+        if (rc == -1)
+        {
+            session->get_socket()->event_handshake_failed_no_detail (
+                session->get_endpoint(),
+                EFAULT);
+            return -1;
+        }
         send_zap_request ();
         zap_request_sent = true;
-        int rc = receive_and_process_zap_reply ();
-        if (rc == -1 || rc == 1)
+
+        //  TODO actually, it is quite unlikely that we can read the ZAP 
+        //  reply already, but removing this has some strange side-effect
+        //  (probably because the pipe's in_active flag is true until a read 
+        //  is attempted)
+        rc = receive_and_process_zap_reply ();
+        if (rc != 0)
             return -1;
+
         zap_reply_received = true;
     }
 

src/null_mechanism.hpp

@@ -61,7 +61,6 @@ namespace zmq
         bool error_command_sent;
         bool ready_command_received;
         bool error_command_received;
-        bool zap_connected;
         bool zap_request_sent;
         bool zap_reply_received;
 

src/plain_server.cpp

@@ -44,6 +44,10 @@ zmq::plain_server_t::plain_server_t (session_base_t *session_,
     zap_client_common_handshake_t (
       session_, peer_address_, options_, sending_welcome)
 {
+    //  Note that there is no point to PLAIN if ZAP is not set up to handle the
+    //  username and password, so if ZAP is not configured it is considered a
+    //  failure.
+    zmq_assert (zap_required());
 }
 
 zmq::plain_server_t::~plain_server_t ()
@@ -173,13 +177,20 @@ int zmq::plain_server_t::process_hello (msg_t *msg_)
     }
 
     //  Use ZAP protocol (RFC 27) to authenticate the user.
-    //  Note that there is no point to PLAIN if ZAP is not set up to handle the
-    //  username and password, so if ZAP is not configured it is considered a
-    //  failure.
     rc = session->zap_connect ();
-    if (rc != 0)
+    if (rc != 0) {
+        session->get_socket ()->event_handshake_failed_no_detail (
+          session->get_endpoint (), EFAULT);
         return -1;
+    }
+
     send_zap_request (username, password);
+    state = waiting_for_zap_reply;
+
+    //  TODO actually, it is quite unlikely that we can read the ZAP 
+    //  reply already, but removing this has some strange side-effect
+    //  (probably because the pipe's in_active flag is true until a read 
+    //  is attempted)
     return receive_and_process_zap_reply () == -1 ? -1 : 0;
 }
 

src/session_base.cpp

@@ -286,8 +286,10 @@ void zmq::session_base_t::read_activated (pipe_t *pipe_)
 
     if (likely (pipe_ == pipe))
         engine->restart_output ();
-    else
+    else {
+        // i.e. pipe_ == zap_pipe
         engine->zap_msg_available ();
+    }
 }
 
 void zmq::session_base_t::write_activated (pipe_t *pipe_)

src/zap_client.cpp

@@ -299,10 +299,7 @@ void zap_client_common_handshake_t::handle_zap_status_code ()
 
 int zap_client_common_handshake_t::receive_and_process_zap_reply ()
 {
-    int rc = zap_client_t::receive_and_process_zap_reply ();
-    if (rc == 1)
-        // TODO shouldn't the state already be this?
-        state = waiting_for_zap_reply;
-    return rc;
+    zmq_assert (state == waiting_for_zap_reply);
+    return zap_client_t::receive_and_process_zap_reply ();
 }
 }

tests/test_security_plain.cpp

@@ -109,6 +109,9 @@ int main (void)
     void *server = zmq_socket (ctx, ZMQ_DEALER);
     assert (server);
     int rc = zmq_setsockopt (server, ZMQ_IDENTITY, "IDENT", 6);
+    const char domain[] = "test";
+    assert (rc == 0);
+    rc = zmq_setsockopt (server, ZMQ_ZAP_DOMAIN, domain, strlen (domain));
     assert (rc == 0);
     int as_server = 1;
     rc = zmq_setsockopt (server, ZMQ_PLAIN_SERVER, &as_server, sizeof (int));
@@ -141,6 +144,8 @@ int main (void)
     client = zmq_socket (ctx, ZMQ_DEALER);
     assert (client);
     as_server = 1;
+    rc = zmq_setsockopt(client, ZMQ_ZAP_DOMAIN, domain, strlen (domain));
+    assert (rc == 0);
     rc = zmq_setsockopt (client, ZMQ_PLAIN_SERVER, &as_server, sizeof (int));
     assert (rc == 0);
     rc = zmq_connect (client, my_endpoint);

tests/test_security_zap.cpp

@@ -59,15 +59,31 @@ static void zap_handler_too_many_parts (void *ctx)
     zap_handler_generic (ctx, zap_too_many_parts);
 }
 
-void test_zap_unsuccessful (void *ctx,
+static void zap_handler_disconnect (void *ctx)
+{
+    zap_handler_generic (ctx, zap_disconnect);
+}
+
+static void zap_handler_do_not_recv (void *ctx)
+{
+    zap_handler_generic (ctx, zap_do_not_recv);
+}
+
+static void zap_handler_do_not_send (void *ctx)
+{
+    zap_handler_generic (ctx, zap_do_not_send);
+}
+
+int expect_new_client_bounce_fail_and_count_monitor_events (
+  void *ctx,
   char *my_endpoint,
   void *server,
-                            void *server_mon,
-                            int expected_event,
-                            int expected_err,
   socket_config_fn socket_config_,
   void *socket_config_data_,
-                            void **client_mon = NULL)
+  void **client_mon,
+  void *server_mon,
+  int expected_event,
+  int expected_err)
 {
     expect_new_client_bounce_fail (ctx, my_endpoint, server, socket_config_,
                                    socket_config_data_, client_mon);
@@ -78,12 +94,54 @@ void test_zap_unsuccessful (void *ctx,
       expect_monitor_event_multiple (server_mon, expected_event, expected_err);
 #endif
 
+    return events_received;
+}
+
+void test_zap_unsuccessful (void *ctx,
+                            char *my_endpoint,
+                            void *server,
+                            void *server_mon,
+                            int expected_event,
+                            int expected_err,
+                            socket_config_fn socket_config_,
+                            void *socket_config_data_,
+                            void **client_mon = NULL)
+{
+    int events_received =
+      expect_new_client_bounce_fail_and_count_monitor_events (
+        ctx, my_endpoint, server, socket_config_, socket_config_data_,
+        client_mon, server_mon, expected_event, expected_err);
+
     //  there may be more than one ZAP request due to repeated attempts by the
     //  client (actually only in case if ZAP status code 300)
     assert (events_received == 0
             || 1 <= zmq_atomic_counter_value (zap_requests_handled));
 }
 
+void test_zap_unsuccessful_no_handler (void *ctx,
+                                       char *my_endpoint,
+                                       void *server,
+                                       void *server_mon,
+                                       int expected_event,
+                                       int expected_err,
+                                       socket_config_fn socket_config_,
+                                       void *socket_config_data_,
+                                       void **client_mon = NULL)
+{
+    int events_received =
+      expect_new_client_bounce_fail_and_count_monitor_events (
+        ctx, my_endpoint, server, socket_config_, socket_config_data_,
+        client_mon, server_mon, expected_event, expected_err);
+
+#ifdef ZMQ_BUILD_DRAFT_API
+    //  there may be more than one ZAP request due to repeated attempts by the
+    //  client
+    assert (events_received > 0);
+#else
+    LIBZMQ_UNUSED (events_received);
+#endif
+}
+
 void test_zap_protocol_error (void *ctx,
                               char *my_endpoint,
                               void *server,
@@ -266,6 +324,72 @@ void test_zap_errors (socket_config_fn server_socket_config_,
                                       client_socket_config_data_);
     shutdown_context_and_server_side (ctx, zap_thread, server, server_mon,
                                       handler);
+
+    //  no ZAP handler
+    fprintf (stderr, "test_zap_unsuccessful no ZAP handler started\n");
+    setup_context_and_server_side (&ctx, &handler, &zap_thread, &server,
+                                   &server_mon, my_endpoint, NULL,
+                                   server_socket_config_);
+    test_zap_unsuccessful_no_handler (
+      ctx, my_endpoint, server, server_mon,
+#ifdef ZMQ_BUILD_DRAFT_API
+      ZMQ_EVENT_HANDSHAKE_FAILED_NO_DETAIL, EFAULT,
+#else
+      0, 0,
+#endif
+      client_socket_config_, client_socket_config_data_);
+    shutdown_context_and_server_side (ctx, zap_thread, server, server_mon,
+                                      handler);
+
+    //  ZAP handler disconnecting on first message
+    fprintf(stderr, "test_zap_unsuccessful ZAP handler disconnects\n");
+    setup_context_and_server_side(&ctx, &handler, &zap_thread, &server,
+        &server_mon, my_endpoint, &zap_handler_disconnect,
+        server_socket_config_);
+    test_zap_unsuccessful_no_handler (
+      ctx, my_endpoint, server, server_mon,
+#ifdef ZMQ_BUILD_DRAFT_API
+      ZMQ_EVENT_HANDSHAKE_FAILED_NO_DETAIL, EPIPE,
+#else
+      0, 0,
+#endif
+      client_socket_config_, client_socket_config_data_);
+    shutdown_context_and_server_side (ctx, zap_thread, server, server_mon,
+                                      handler, true);
+
+    //  ZAP handler does not read request
+    fprintf (stderr,
+             "test_zap_unsuccessful ZAP handler does not read request\n");
+    setup_context_and_server_side (&ctx, &handler, &zap_thread, &server,
+        &server_mon, my_endpoint, &zap_handler_do_not_recv,
+        server_socket_config_);
+    test_zap_unsuccessful_no_handler (
+      ctx, my_endpoint, server, server_mon,
+#ifdef ZMQ_BUILD_DRAFT_API
+      ZMQ_EVENT_HANDSHAKE_FAILED_NO_DETAIL, EPIPE,
+#else
+      0, 0,
+#endif
+      client_socket_config_, client_socket_config_data_);
+    shutdown_context_and_server_side (ctx, zap_thread, server, server_mon,
+                                      handler);
+
+    //  ZAP handler does not send reply
+    fprintf (stderr,
+             "test_zap_unsuccessful ZAP handler does not write reply\n");
+    setup_context_and_server_side (
+      &ctx, &handler, &zap_thread, &server, &server_mon, my_endpoint,
+      &zap_handler_do_not_send, server_socket_config_);
+    test_zap_unsuccessful_no_handler (
+      ctx, my_endpoint, server, server_mon,
+#ifdef ZMQ_BUILD_DRAFT_API
+      ZMQ_EVENT_HANDSHAKE_FAILED_NO_DETAIL, EPIPE,
+#else
+      0, 0,
+#endif
+      client_socket_config_, client_socket_config_data_);
+    shutdown_context_and_server_side (ctx, zap_thread, server, server_mon,
+                                      handler);
 }
 
 int main (void)

tests/testutil_security.hpp

@@ -49,7 +49,8 @@ void socket_config_null_server (void *server, void *server_secret)
 {
     LIBZMQ_UNUSED (server_secret);
 
-    int rc = zmq_setsockopt (server, ZMQ_ZAP_DOMAIN, test_zap_domain, 7);
+    int rc = zmq_setsockopt (server, ZMQ_ZAP_DOMAIN, test_zap_domain,
+                             strlen (test_zap_domain));
     assert (rc == 0);
 }
 
@@ -61,7 +62,8 @@ void socket_config_plain_client (void *server, void *server_secret)
 {
     LIBZMQ_UNUSED (server_secret);
 
-    int rc = zmq_setsockopt (server, ZMQ_PLAIN_PASSWORD, test_plain_password, 8);
+    int rc =
+      zmq_setsockopt (server, ZMQ_PLAIN_PASSWORD, test_plain_password, 8);
     assert (rc == 0);
 
     rc = zmq_setsockopt (server, ZMQ_PLAIN_USERNAME, test_plain_username, 8);
@@ -73,8 +75,13 @@ void socket_config_plain_server (void *server, void *server_secret)
     LIBZMQ_UNUSED (server_secret);
 
     int as_server = 1;
-    int rc = zmq_setsockopt (server, ZMQ_PLAIN_SERVER, &as_server, sizeof (int));
+    int rc =
+      zmq_setsockopt (server, ZMQ_PLAIN_SERVER, &as_server, sizeof (int));
     assert (rc == 0);
+
+    rc = zmq_setsockopt (server, ZMQ_ZAP_DOMAIN, test_zap_domain,
+                         strlen (test_zap_domain));
+    assert(rc == 0);
 }
 
 //  CURVE specific functions
@@ -97,11 +104,16 @@ void setup_testutil_security_curve ()
 void socket_config_curve_server (void *server, void *server_secret)
 {
     int as_server = 1;
-    int rc = zmq_setsockopt (server, ZMQ_CURVE_SERVER, &as_server, sizeof (int));
+    int rc =
+      zmq_setsockopt (server, ZMQ_CURVE_SERVER, &as_server, sizeof (int));
     assert (rc == 0);
 
     rc = zmq_setsockopt (server, ZMQ_CURVE_SECRETKEY, server_secret, 41);
     assert (rc == 0);
+
+    rc = zmq_setsockopt (server, ZMQ_ZAP_DOMAIN, test_zap_domain,
+                         strlen (test_zap_domain));
+    assert(rc == 0);
 }
 
 struct curve_client_data_t
@@ -141,7 +153,10 @@ enum zap_protocol_t
     zap_wrong_version,
     zap_wrong_request_id,
     zap_status_invalid,
-  zap_too_many_parts
+    zap_too_many_parts,
+    zap_disconnect,
+    zap_do_not_recv,
+    zap_do_not_send
 };
 
 void *zap_requests_handled;
@@ -165,11 +180,15 @@ void zap_handler_generic (void *ctx,
     assert (rc == 2);
 
     zmq_pollitem_t items[] = {
-      {control, 0, ZMQ_POLLIN, 0}, {handler, 0, ZMQ_POLLIN, 0},
+      {control, 0, ZMQ_POLLIN, 0},
+      {handler, 0, ZMQ_POLLIN, 0},
     };
 
+    // if ordered not to receive the request, ignore the second poll item
+    const int numitems = (zap_protocol == zap_do_not_recv) ? 1 : 2;
+
     //  Process ZAP requests forever
-    while (zmq_poll (items, 2, -1) >= 0) {
+    while (zmq_poll (items, numitems, -1) >= 0) {
         if (items[0].revents & ZMQ_POLLIN) {
             char *buf = s_recv (control);
             assert (buf);
@@ -183,6 +202,11 @@ void zap_handler_generic (void *ctx,
         char *version = s_recv (handler);
         if (!version)
             break; //  Terminating - peer's socket closed
+        if (zap_protocol == zap_disconnect)
+        {
+            free (version);
+            break;
+        }
 
         char *sequence = s_recv (handler);
         char *domain = s_recv (handler);
@@ -200,15 +224,13 @@ void zap_handler_generic (void *ctx,
 
             authentication_succeeded =
               streq (client_key_text, valid_client_public);
-        }
-        else if (streq(mechanism, "PLAIN"))
-        {
-            char client_username[32];
+        } else if (streq (mechanism, "PLAIN")) {
+            char client_username [32];
             int size = zmq_recv (handler, client_username, 32, 0);
             assert (size > 0);
             client_username [size] = 0;
 
-            char client_password[32];
+            char client_password [32];
             size = zmq_recv (handler, client_password, 32, 0);
             assert (size > 0);
             client_password [size] = 0;
@@ -216,13 +238,9 @@ void zap_handler_generic (void *ctx,
             authentication_succeeded =
               streq (test_plain_username, client_username)
               && streq (test_plain_password, client_password);
-        }
-        else if (streq(mechanism, "NULL"))
-        {
+        } else if (streq (mechanism, "NULL")) {
             authentication_succeeded = true;
-        }
-        else
-        {
+        } else {
             fprintf (stderr, "Unsupported mechanism: %s\n", mechanism);
             assert (false);
         }
@@ -258,12 +276,14 @@ void zap_handler_generic (void *ctx,
             if (zap_protocol == zap_too_many_parts) {
                 s_sendmore (handler, "");
             }
+            if (zap_protocol != zap_do_not_send)
                 s_send (handler, "");
         } else {
             s_sendmore (handler, "400");
             s_sendmore (handler, "Invalid client public key");
             s_sendmore (handler, "");
-            s_send (handler, "");
+            if (zap_protocol != zap_do_not_send)
+                s_send(handler, "");
         }
         free (version);
         free (sequence);
@@ -278,8 +298,11 @@ void zap_handler_generic (void *ctx,
     assert (rc == 0);
     close_zero_linger (handler);
 
-    rc = s_send (control, "STOPPED");
-    assert (rc == 7);
+    if (zap_protocol != zap_disconnect)
+    {
+        rc = s_send(control, "STOPPED");
+        assert(rc == 7);
+    }
     close_zero_linger (control);
 }
 
@@ -314,7 +337,7 @@ void setup_handshake_socket_monitor (void *ctx,
 
 void setup_context_and_server_side (
   void **ctx,
-  void **handler,
+  void **zap_control,
   void **zap_thread,
   void **server,
   void **server_mon,
@@ -331,17 +354,20 @@ void setup_context_and_server_side (
     zap_requests_handled = zmq_atomic_counter_new ();
     assert (zap_requests_handled != NULL);
 
-    *handler = zmq_socket (*ctx, ZMQ_REP);
-    assert (*handler);
-    int rc = zmq_bind (*handler, "inproc://handler-control");
+    *zap_control = zmq_socket (*ctx, ZMQ_REP);
+    assert (*zap_control);
+    int rc = zmq_bind (*zap_control, "inproc://handler-control");
     assert (rc == 0);
 
+    if (zap_handler_) {
         *zap_thread = zmq_threadstart (zap_handler_, *ctx);
 
-    char *buf = s_recv (*handler);
+        char *buf = s_recv (*zap_control);
         assert (buf);
         assert (streq (buf, "GO"));
         free (buf);
+    } else
+        *zap_thread = NULL;
 
     //  Server socket will accept connections
     *server = zmq_socket (*ctx, ZMQ_DEALER);
@@ -349,7 +375,7 @@ void setup_context_and_server_side (
 
     socket_config_ (*server, socket_config_data_);
 
-    rc = zmq_setsockopt (*server, ZMQ_IDENTITY, identity, strlen(identity));
+    rc = zmq_setsockopt (*server, ZMQ_IDENTITY, identity, strlen (identity));
     assert (rc == 0);
 
     rc = zmq_bind (*server, "tcp://127.0.0.1:*");
@@ -368,17 +394,20 @@ void shutdown_context_and_server_side (void *ctx,
                                        void *zap_thread,
                                        void *server,
                                        void *server_mon,
-                                       void *handler)
+                                       void *zap_control,
+                                       bool zap_handler_stopped = false)
 {
-    int rc = s_send (handler, "STOP");
+    if (zap_thread && !zap_handler_stopped) {
+        int rc = s_send (zap_control, "STOP");
         assert (rc == 4);
-    char *buf = s_recv (handler);
+        char *buf = s_recv (zap_control);
         assert (buf);
         assert (streq (buf, "STOPPED"));
         free (buf);
-    rc = zmq_unbind (handler, "inproc://handler-control");
+        rc = zmq_unbind (zap_control, "inproc://handler-control");
         assert (rc == 0);
-    close_zero_linger (handler);
+    }
+    close_zero_linger(zap_control);
 
 #ifdef ZMQ_BUILD_DRAFT_API
     close_zero_linger (server_mon);
@@ -386,9 +415,10 @@ void shutdown_context_and_server_side (void *ctx,
     close_zero_linger (server);
 
     //  Wait until ZAP handler terminates
+    if (zap_thread)
         zmq_threadclose (zap_thread);
 
-    rc = zmq_ctx_term (ctx);
+    int rc = zmq_ctx_term (ctx);
     assert (rc == 0);
 
     zmq_atomic_counter_destroy (&zap_requests_handled);
@@ -408,8 +438,7 @@ void *create_and_connect_client (void *ctx,
     int rc = zmq_connect (client, my_endpoint);
     assert (rc == 0);
 
-    if (client_mon)
-    {
+    if (client_mon) {
         setup_handshake_socket_monitor (ctx, client, client_mon,
                                         "inproc://client-monitor");
     }
@@ -436,8 +465,10 @@ void expect_new_client_bounce_fail (void *ctx,
 //  by reference, if not null, and event number by value. Returns -1
 //  in case of error.
 
-static int
-get_monitor_event_internal (void *monitor, int *value, char **address, int recv_flag)
+static int get_monitor_event_internal (void *monitor,
+                                       int *value,
+                                       char **address,
+                                       int recv_flag)
 {
     //  First frame in message contains event number and value
     zmq_msg_t msg;
@@ -507,8 +538,7 @@ int get_monitor_event (void *monitor, int *value, char **address)
 void expect_monitor_event (void *monitor, int expected_event)
 {
     int event = get_monitor_event (monitor, NULL, NULL);
-    if (event != expected_event)
-    {
+    if (event != expected_event) {
         fprintf (stderr, "Expected monitor event %x but received %x\n",
                  expected_event, event);
         assert (event == expected_event);
@@ -522,8 +552,7 @@ void print_unexpected_event (int event,
                              int expected_event,
                              int expected_err)
 {
-  fprintf(
-    stderr,
+    fprintf (stderr,
              "Unexpected event: 0x%x, value = %i/0x%x (expected: 0x%x, value "
              "= %i/0x%x)\n",
              event, err, err, expected_event, expected_err, expected_err);
@@ -550,14 +579,15 @@ int expect_monitor_event_multiple (void *server_mon,
     int err;
     while (
       (event = get_monitor_event_with_timeout (server_mon, &err, NULL, timeout))
-      != -1 || !count_of_expected_events) {
+        != -1
+      || !count_of_expected_events) {
         if (event == -1) {
             if (optional)
                 break;
             wait_time += timeout;
             fprintf (stderr,
                      "Still waiting for first event after %ims (expected event "
-                     "%x (value %i/%x))\n",
+                     "%x (value %i/0x%x))\n",
                      wait_time, expected_event, expected_err, expected_err);
             continue;
         }
@@ -565,12 +595,13 @@ int expect_monitor_event_multiple (void *server_mon,
         // ECONNRESET can happen on very slow machines, when the engine writes
         // to the peer and then tries to read the socket before the peer reads
         // ECONNABORTED happens when a client aborts a connection via RST/timeout
-        if (event == ZMQ_EVENT_HANDSHAKE_FAILED_NO_DETAIL &&
-                (err == EPIPE || err == ECONNRESET || err == ECONNABORTED)) {
-            fprintf (
-              stderr,
-              "Ignored event (skipping any further events): %x (err = %i)\n",
-              event, err);
+        if (event == ZMQ_EVENT_HANDSHAKE_FAILED_NO_DETAIL
+            && ((err == EPIPE && expected_err != EPIPE) || err == ECONNRESET
+                || err == ECONNABORTED)) {
+            fprintf (stderr,
+                     "Ignored event (skipping any further events): %x (err = "
+                     "%i == %s)\n",
+                     event, err, zmq_strerror (err));
             client_closed_connection = 1;
             break;
         }
@@ -581,7 +612,8 @@ int expect_monitor_event_multiple (void *server_mon,
         }
         ++count_of_expected_events;
     }
-    assert (optional || count_of_expected_events > 0 || client_closed_connection);
+    assert (optional || count_of_expected_events > 0
+            || client_closed_connection);
 
     return count_of_expected_events;
 }
@@ -600,8 +632,8 @@ int expect_monitor_event_multiple (void *server_mon,
                     || err == ECONNABORTED)) {                                 \
                 fprintf (stderr,                                               \
                          "Ignored event (skipping any further events): %x "    \
-                         "(err = %i)\n",                                       \
-                         event, err);                                          \
+                         "(err = %i == %s)\n",                                 \
+                         event, err, zmq_strerror (err));                      \
                 continue;                                                      \
             }                                                                  \
             ++event_count;                                                     \