From b3045d1adfee180910606213963096e487c590f9 Mon Sep 17 00:00:00 2001
From: "Roger A. Light" <roger@atchoo.org>
Date: Thu, 10 Jun 2021 21:33:24 +0100
Subject: [PATCH] Fix pattern matching with invalid prefix.

---
 lib/util_topic.c            | 3 +++
 test/unit/util_topic_test.c | 5 +++++
 2 files changed, 8 insertions(+)

diff --git a/lib/util_topic.c b/lib/util_topic.c
index 2454f0cb..8b4df859 100644
--- a/lib/util_topic.c
+++ b/lib/util_topic.c
@@ -193,6 +193,7 @@ static int topic_matches_sub(const char *sub, const char *topic, const char *cli
 {
 	size_t spos;
 	const char *pattern_check;
+	const char *lastchar = NULL;
 
 	if(!result) return MOSQ_ERR_INVAL;
 	*result = false;
@@ -214,6 +215,7 @@ static int topic_matches_sub(const char *sub, const char *topic, const char *cli
 			return MOSQ_ERR_INVAL;
 		}
 		if(match_patterns &&
+				(lastchar == NULL || lastchar[0] == '/') &&
 				sub[0] == '%' &&
 				(sub[1] == 'c' || sub[1] == 'u') &&
 				(sub[2] == '/' || sub[2] == '\0')
@@ -337,6 +339,7 @@ static int topic_matches_sub(const char *sub, const char *topic, const char *cli
 				return MOSQ_ERR_SUCCESS;
 			}
 		}
+		lastchar = sub-1;
 	}
 	if((topic[0] != 0 || sub[0] != 0)){
 		*result = false;
diff --git a/test/unit/util_topic_test.c b/test/unit/util_topic_test.c
index a104af87..a5f349db 100644
--- a/test/unit/util_topic_test.c
+++ b/test/unit/util_topic_test.c
@@ -411,6 +411,11 @@ static void TEST_pattern_both(void)
 	rc = mosquitto_topic_matches_sub_with_pattern("test/%username/%client", "test/username/clientid", "clientid", "username", &match);
 	CU_ASSERT_EQUAL(rc, MOSQ_ERR_SUCCESS);
 	CU_ASSERT_EQUAL(match, false);
+
+	/* Not a pattern */
+	rc = mosquitto_topic_matches_sub_with_pattern("test/a%u/a%c", "test/ausername/aclientid", "clientid", "username", &match);
+	CU_ASSERT_EQUAL(rc, MOSQ_ERR_SUCCESS);
+	CU_ASSERT_EQUAL(match, false);
 }
 
 static void TEST_pattern_wildcard(void)