resolved: don't discard mDNS queries with bad flags

Even though RFC 6762 specifies these bits MUST be zero, it also says they MUST
be ignored on reception.

diff --git a/src/resolve/resolved-dns-packet.c b/src/resolve/resolved-dns-packet.c
index a51514a8de894be5df7c231c7e99567861ca17ee..9778f5ee6b5645b248eb388149b3ed73a86c8a20 100644 (file)
--- a/src/resolve/resolved-dns-packet.c
+++ b/src/resolve/resolved-dns-packet.c
@@ -326,13 +326,10 @@ int dns_packet_validate_query(DnsPacket *p) {
                 break;
 
         case DNS_PROTOCOL_MDNS:
-                /* RFC 6762, Section 18 */
-                if (DNS_PACKET_AA(p)    != 0 ||
-                    DNS_PACKET_RD(p)    != 0 ||
-                    DNS_PACKET_RA(p)    != 0 ||
-                    DNS_PACKET_AD(p)    != 0 ||
-                    DNS_PACKET_CD(p)    != 0 ||
-                    DNS_PACKET_RCODE(p) != 0)
+                /* RFC 6762, Section 18 specifies that messages with non-zero RCODE
+                 * must be silently ignored, and that we must ignore the values of
+                 * AA, RD, RA, AD, and CD bits. */
+                if (DNS_PACKET_RCODE(p) != 0)
                         return -EBADMSG;
 
                 break;