resolved: install answers to mDNS transactions too

Currently resolving mDNS requests doesn't work because in
dns_transaction_process_reply() no answer gets installed into
mDNS transactions.

When receiving a mDNS reply we should not check for query section
equivalence of the request and its corresponsing response. But still
we need to install answers to mDNS transactions to make it possible
to actually resolve mDNS requests.

Signed-off-by: Dmitry Rozhkov <dmitry.rozhkov@linux.intel.com>

diff --git a/src/resolve/resolved-dns-transaction.c b/src/resolve/resolved-dns-transaction.c
index 2fce44ec8b74e0d821572e2c8f0a4689cdda39e7..ba38e0af789576a2c191340f880acb97f17a73d4 100644 (file)
--- a/src/resolve/resolved-dns-transaction.c
+++ b/src/resolve/resolved-dns-transaction.c
@@ -1003,15 +1003,20 @@ void dns_transaction_process_reply(DnsTransaction *t, DnsPacket *p) {
         if (r > 0) /* Transaction got restarted... */
                 return;
 
-        if (IN_SET(t->scope->protocol, DNS_PROTOCOL_DNS, DNS_PROTOCOL_LLMNR)) {
-
-                /* Only consider responses with equivalent query section to the request */
-                r = dns_packet_is_reply_for(p, t->key);
-                if (r < 0)
-                        goto fail;
-                if (r == 0) {
-                        dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
-                        return;
+        if (IN_SET(t->scope->protocol, DNS_PROTOCOL_DNS, DNS_PROTOCOL_LLMNR, DNS_PROTOCOL_MDNS)) {
+
+                /* When dealing with protocols other than mDNS only consider responses with
+                 * equivalent query section to the request. For mDNS this check doesn't make
+                 * sense, because the section 6 of RFC6762 states that "Multicast DNS responses MUST NOT
+                 * contain any questions in the Question Section". */
+                if (t->scope->protocol != DNS_PROTOCOL_MDNS) {
+                        r = dns_packet_is_reply_for(p, t->key);
+                        if (r < 0)
+                                goto fail;
+                        if (r == 0) {
+                                dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
+                                return;
+                        }
                 }
 
                 /* Install the answer as answer to the transaction */