resolved: the llmnr destination address check applies to queries, not to responses

[elogind.git] / src / resolve / resolved-dns-scope.c

diff --git a/src/resolve/resolved-dns-scope.c b/src/resolve/resolved-dns-scope.c
index 5742f3ef472c3bb98cf7be8fee1dcf465c0dc5b4..b975ac409230797e89915cf6cf64cf06da2e981e 100644 (file)
--- a/src/resolve/resolved-dns-scope.c
+++ b/src/resolve/resolved-dns-scope.c
@@ -452,6 +452,18 @@ void dns_scope_process_query(DnsScope *s, DnsStream *stream, DnsPacket *p) {
         if (p->protocol != DNS_PROTOCOL_LLMNR)
                 return;
 
+        if (p->ipproto == IPPROTO_UDP) {
+                /* Don't accept UDP queries directed to anything but
+                 * the LLMNR multicast addresses. See RFC 4795,
+                 * section 2.5.*/
+
+                if (p->family == AF_INET && !in_addr_equal(AF_INET, &p->destination, (union in_addr_union*) &LLMNR_MULTICAST_IPV4_ADDRESS))
+                        return;
+
+                if (p->family == AF_INET6 && !in_addr_equal(AF_INET6, &p->destination, (union in_addr_union*) &LLMNR_MULTICAST_IPV6_ADDRESS))
+                        return;
+        }
+
         r = dns_packet_extract(p);
         if (r < 0) {
                 log_debug("Failed to extract resources from incoming packet: %s", strerror(-r));