resolved: empty "ipv4hint" and "ipv6hint" SvcParams are invalid

According to RFC 9460 "An empty list of addresses is invalid."

https://www.rfc-editor.org/rfc/rfc9460.html#section-7.3

diff --git a/src/resolve/resolved-dns-packet.c b/src/resolve/resolved-dns-packet.c
index 4c82d38bcc29072cba9630241efdbb8092aa91ba..1d235b4aff78a206d95bbe0d00694fc1ed359c36 100644 (file)
--- a/src/resolve/resolved-dns-packet.c
+++ b/src/resolve/resolved-dns-packet.c
@@ -1789,9 +1789,9 @@ static bool dns_svc_param_is_valid(DnsSvcParam *i) {
 
         /* RFC 9460, section 7.3: addrs must exactly fill SvcParamValue */
         case DNS_SVC_PARAM_KEY_IPV4HINT:
-                return i->length % (sizeof (struct in_addr)) == 0;
+                return i->length > 0 && i->length % (sizeof (struct in_addr)) == 0;
         case DNS_SVC_PARAM_KEY_IPV6HINT:
-                return i->length % (sizeof (struct in6_addr)) == 0;
+                return i->length > 0 && i->length % (sizeof (struct in6_addr)) == 0;
 
         /* Otherwise, permit any value */
         default: