From: Willy Tarreau <w@1wt.eu>
Date: Mon, 11 May 2026 13:34:15 +0000 (+0200)
Subject: BUG/MINOR: mqtt: connect parser uses wrong bit field for TOPIC_ALIAS_MAXIMUM
X-Git-Url: http://www.kaiwu.me/postgresql/commit/?a=commitdiff_plain;h=57878f3b5cf9048e844282e757972e9896180fa4;p=haproxy.git

BUG/MINOR: mqtt: connect parser uses wrong bit field for TOPIC_ALIAS_MAXIMUM

In mqtt_parse_connect(), the MQTT_PROP_TOPIC_ALIAS_MAXIMUM case was checking
and setting MQTT_FN_BIT_TOPIC_ALIAS instead of MQTT_FN_BIT_TOPIC_ALIAS_MAXIMUM.
This means duplicate detection for Topic-Alias-Maximum property was using the
wrong bitmask, and the actual Topic-Alias-Maximum bit was never set, making
duplicate detection ineffective for this property. The CONNACK parser already
had this correct.
---

diff --git a/src/mqtt.c b/src/mqtt.c
index 9ff977ef6..772d683c4 100644
--- a/src/mqtt.c
+++ b/src/mqtt.c
@@ -789,10 +789,10 @@ static int mqtt_parse_connect(struct ist parser, struct mqtt_pkt *mpkt)
 				break;
 
 			case MQTT_PROP_TOPIC_ALIAS_MAXIMUM:
-				if (fields & MQTT_FN_BIT_TOPIC_ALIAS)
+				if (fields & MQTT_FN_BIT_TOPIC_ALIAS_MAXIMUM)
 					goto end;
 				props = mqtt_read_2byte_int(istnext(props), &mpkt->data.connect.var_hdr.props.topic_alias_maximum);
-				fields |= MQTT_FN_BIT_TOPIC_ALIAS;
+				fields |= MQTT_FN_BIT_TOPIC_ALIAS_MAXIMUM;
 				break;
 
 			case MQTT_PROP_REQUEST_RESPONSE_INFORMATION: