Fix incorrect return code being sent in DISCONNECT.

This is for when a client session is taken over.

Closes #2607. Thanks to der-b

ChangeLog.txt

@@ -16,6 +16,8 @@ Broker:
 - Fix bridges not sending failure notification messages to the local broker if
   the remote bridge connection fails. Closes #2467. Closes #1488.
 - Fix some PUBLISH messages not being counted in $SYS stats. Closes #2448.
+- Fix incorrect return code being sent in DISCONNECT when a client session is
+  taken over. Closes #2607.
 
 Client library:
 - Fix threads library detection on Windows under cmake. Bumps the minimum

src/handle_connect.c

@@ -205,6 +205,10 @@ int connect__on_authorised(struct mosquitto *context, void *auth_data_out, uint1
 		found_context->clean_start = true;
 		found_context->session_expiry_interval = 0;
 		mosquitto__set_state(found_context, mosq_cs_duplicate);
+
+		if(found_context->protocol == mosq_p_mqtt5){
+			send__disconnect(found_context, MQTT_RC_SESSION_TAKEN_OVER, NULL);
+		}
 		do_disconnect(found_context, MOSQ_ERR_SUCCESS);
 	}
 

test/broker/01-connect-take-over.py

@@ -0,0 +1,34 @@
+#!/usr/bin/env python3
+
+# MQTT v5 session takeover test
+
+from mosq_test_helper import *
+
+port = mosq_test.get_port()
+broker = mosq_test.start_broker(filename=os.path.basename(__file__), port=port)
+
+try:
+    rc = 1
+    connect_packet = mosq_test.gen_connect("take-over", proto_ver=5)
+    connack_packet = mosq_test.gen_connack(rc=0, proto_ver=5)
+    disconnect_packet = mosq_test.gen_disconnect(reason_code=mqtt5_rc.MQTT_RC_SESSION_TAKEN_OVER, proto_ver=5)
+
+    sock1 = mosq_test.do_client_connect(connect_packet, connack_packet, port=port)
+    sock2 = mosq_test.do_client_connect(connect_packet, connack_packet, port=port)
+    mosq_test.expect_packet(sock1, "disconnect", disconnect_packet)
+    mosq_test.do_ping(sock2)
+
+    sock2.close()
+    sock1.close()
+    rc = 0
+except mosq_test.TestError:
+    pass
+except Exception as e:
+    print(e)
+finally:
+    broker.terminate()
+    broker.wait()
+    (stdo, stde) = broker.communicate()
+    if rc:
+        print(stde.decode('utf-8'))
+        exit(rc)

test/broker/Makefile

@@ -28,6 +28,7 @@ msg_sequence_test:
 	./01-connect-disconnect-v5.py
 	./01-connect-max-connections.py
 	./01-connect-max-keepalive.py
+	./01-connect-take-over.py
 	./01-connect-uname-no-password-denied.py
 	./01-connect-uname-or-anon.py
 	./01-connect-uname-password-denied-no-will.py

test/broker/test.py

@@ -10,6 +10,7 @@ tests = [
     (1, './01-connect-disconnect-v5.py'),
     (1, './01-connect-max-connections.py'),
     (1, './01-connect-max-keepalive.py'),
+    (1, './01-connect-take-over.py'),
     (1, './01-connect-uname-no-password-denied.py'),
     (1, './01-connect-uname-or-anon.py'),
     (1, './01-connect-uname-password-denied-no-will.py'),