dns: Fix memory leak in dns_server_addr_parse

When the DNS server's address count is already full (exceeds the
limit of 8), the function returned early without freeing the
successfully resolved addrinfo struct. Fix this by checking the
limit before executing the DNS lookup.

Github: #1055
Change-Id: I7ec318c86af994284d1c6272e3bbe2b1ede160fd
Signed-off-by: saddamr3e <saddamr3e@gmail.com>
Acked-by: Heiko Hund <heiko@openvpn.net>
Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/1712
Message-Id: <20260618061835.16448-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg37209.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>

Author: saddamr3e

src/openvpn/dns.c

@@ -114,13 +114,13 @@ dns_server_addr_parse(struct dns_server *server, const char *addr)
         addr = addrcopy;
     }
 
-    struct addrinfo *ai = NULL;
-    if (openvpn_getaddrinfo(0, addr, NULL, 0, NULL, af, &ai) != 0)
+    if (server->addr_count >= SIZE(server->addr))
     {
         return false;
     }
 
-    if (server->addr_count >= SIZE(server->addr))
+    struct addrinfo *ai = NULL;
+    if (openvpn_getaddrinfo(0, addr, NULL, 0, NULL, af, &ai) != 0)
     {
         return false;
     }