Fix incomgin QoS 2 with max_inflight_messages set to 1.

Closes #1332. Thanks to xmas79.

ChangeLog.txt

@@ -6,6 +6,8 @@ Broker:
   Closes #1272.
 - Windows: Allow other applications access to the log file when running.
   Closes #515.
+- Fix incoming QoS 2 messages being blocked when `max_inflight_messages` was
+  set to 1. Closes #1332.
 
 Client library:
 - Fix MQTT v5 subscription options being incorrectly set for MQTT v3

src/handle_publish.c

@@ -331,7 +331,6 @@ int handle__publish(struct mosquitto_db *db, struct mosquitto *context)
 			break;
 		case 2:
 			if(dup == 0){
-				util__decrement_receive_quota(context);
 				res = db__message_insert(db, context, mid, mosq_md_in, qos, retain, stored, NULL);
 			}else{
 				res = 0;

test/broker/03-publish-qos1-max-inflight.py

@@ -0,0 +1,46 @@
+#!/usr/bin/env python3
+
+# Test whether a PUBLISH to a topic with QoS 1 results in the correct packet flow.
+# With max_inflight_messages set to 1
+
+from mosq_test_helper import *
+
+def write_config(filename, port):
+    with open(filename, 'w') as f:
+        f.write("port %d\n" % (port))
+        f.write("max_inflight_messages 1\n")
+
+port = mosq_test.get_port()
+conf_file = os.path.basename(__file__).replace('.py', '.conf')
+write_config(conf_file, port)
+
+
+rc = 1
+keepalive = 60
+connect_packet = mosq_test.gen_connect("pub-qos1-test", keepalive=keepalive)
+connack_packet = mosq_test.gen_connack(rc=0)
+
+mid = 311
+publish_packet = mosq_test.gen_publish("pub/qos1/test", qos=1, mid=mid, payload="message")
+puback_packet = mosq_test.gen_puback(mid)
+
+port = mosq_test.get_port()
+broker = mosq_test.start_broker(filename=os.path.basename(__file__), use_conf=True, port=port)
+
+try:
+    sock = mosq_test.do_client_connect(connect_packet, connack_packet, port=port, timeout=10)
+    mosq_test.do_send_receive(sock, publish_packet, puback_packet, "puback")
+
+    rc = 0
+
+    sock.close()
+finally:
+    os.remove(conf_file)
+    broker.terminate()
+    broker.wait()
+    (stdo, stde) = broker.communicate()
+    if rc:
+        print(stde.decode('utf-8'))
+
+exit(rc)
+

test/broker/03-publish-qos2-max-inflight.py

@@ -0,0 +1,49 @@
+#!/usr/bin/env python3
+
+# Test whether a PUBLISH to a topic with QoS 2 results in the correct packet flow.
+# With max_inflight_messages set to 1
+
+from mosq_test_helper import *
+
+def write_config(filename, port):
+    with open(filename, 'w') as f:
+        f.write("port %d\n" % (port))
+        f.write("max_inflight_messages 1\n")
+
+port = mosq_test.get_port()
+conf_file = os.path.basename(__file__).replace('.py', '.conf')
+write_config(conf_file, port)
+
+
+rc = 1
+keepalive = 60
+connect_packet = mosq_test.gen_connect("pub-qos2-test", keepalive=keepalive)
+connack_packet = mosq_test.gen_connack(rc=0)
+
+mid = 312
+publish_packet = mosq_test.gen_publish("pub/qos2/test", qos=2, mid=mid, payload="message")
+pubrec_packet = mosq_test.gen_pubrec(mid)
+pubrel_packet = mosq_test.gen_pubrel(mid)
+pubcomp_packet = mosq_test.gen_pubcomp(mid)
+
+port = mosq_test.get_port()
+broker = mosq_test.start_broker(filename=os.path.basename(__file__), use_conf=True, port=port)
+
+try:
+    sock = mosq_test.do_client_connect(connect_packet, connack_packet, port=port, timeout=10)
+    mosq_test.do_send_receive(sock, publish_packet, pubrec_packet, "pubrec")
+    mosq_test.do_send_receive(sock, pubrel_packet, pubcomp_packet, "pubcomp")
+
+    rc = 0
+
+    sock.close()
+finally:
+    os.remove(conf_file)
+    broker.terminate()
+    broker.wait()
+    (stdo, stde) = broker.communicate()
+    if rc:
+        print(stde.decode('utf-8'))
+
+exit(rc)
+

test/broker/Makefile

@@ -101,6 +101,7 @@ endif
 	./03-publish-qos1-no-subscribers-v5.py
 	./03-publish-qos1-retain-disabled.py
 	./03-publish-qos1.py
+	./03-publish-qos2-max-inflight.py
 	./03-publish-qos2.py
 
 04 :

test/broker/test.py

@@ -79,6 +79,7 @@ tests = [
     (1, './03-publish-qos1-no-subscribers-v5.py'),
     (1, './03-publish-qos1-retain-disabled.py'),
     (1, './03-publish-qos1.py'),
+    (1, './03-publish-qos2-max-inflight.py'),
     (1, './03-publish-qos2.py'),
 
     (1, './04-retain-check-source-persist.py'),