From: Martin Röder <mroeder@metz-connect.com>
Date: Wed, 18 Oct 2023 16:32:34 +0000 (+0200)
Subject: Fix AVL tree traversal in cache_record_find and cache_host_is_known
X-Git-Url: http://git.openwrt.org/feed/telephony.git%5Eaffee75beff7ed8445f6bc84deff13465c331027?a=commitdiff_plain;h=c286c51a9bd931d023a55988c0e89574ee6d8ffa;p=project%2Fmdnsd.git

Fix AVL tree traversal in cache_record_find and cache_host_is_known

The AVL tree traversal in both functions systematically misses the last
AVL tree element. This can lead to duplicate cache entries and lookup
failures.

The fix duplicates the correct AVL tree traversal approach of
cache_dump_recursive().

Signed-off-by: Martin Röder <mroeder@metz-connect.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
---

diff --git a/cache.c b/cache.c
index 8c851a3..0ed52d7 100644
--- a/cache.c
+++ b/cache.c
@@ -197,13 +197,10 @@ cache_record_find(char *record, int type, int port, int rdlength, uint8_t *rdata
 {
 	struct cache_record *l = avl_find_element(&records, record, l, avl);
 
-	if (!l)
-		return NULL;
-
-	while (l && !avl_is_last(&records, &l->avl) && !strcmp(l->record, record)) {
+	while (l && !strcmp(l->record, record)) {
 		struct cache_record *r = l;
 
-		l = avl_next_element(l, avl);
+		l = !avl_is_last(&records, &l->avl) ? avl_next_element(l, avl) : NULL;
 		if (r->type != type)
 			continue;
 
@@ -233,13 +230,10 @@ cache_host_is_known(char *record)
 {
 	struct cache_record *l = avl_find_element(&records, record, l, avl);
 
-	if (!l)
-		return 0;
-
-	while (l && !avl_is_last(&records, &l->avl) && !strcmp(l->record, record)) {
+	while (l && !strcmp(l->record, record)) {
 		struct cache_record *r = l;
 
-		l = avl_next_element(l, avl);
+		l = !avl_is_last(&records, &l->avl) ? avl_next_element(l, avl) : NULL;
 		if ((r->type != TYPE_A) && (r->type != TYPE_AAAA))
 			continue;
 		return 1;