resolved: degrade the feature level on explicit failure

Previously, we would only degrade on packet loss, but when adding EDNS0 support,
we also have to handle the case where the server replies with an explicit error.

diff --git a/src/resolve/resolved-dns-server.c b/src/resolve/resolved-dns-server.c
index 5fc7c3187f36d224095f7190e633edcd3d7a14d6..c5396a03c82db32bebe2213a41cec921826f69e4 100644 (file)
--- a/src/resolve/resolved-dns-server.c
+++ b/src/resolve/resolved-dns-server.c
@@ -253,6 +253,16 @@ void dns_server_packet_lost(DnsServer *s, DnsServerFeatureLevel features, usec_t
         s->resend_timeout = MIN(s->resend_timeout * 2, DNS_TIMEOUT_MAX_USEC);
 }
 
+void dns_server_packet_failed(DnsServer *s, DnsServerFeatureLevel features) {
+        assert(s);
+        assert(s->manager);
+
+        if (s->possible_features != features)
+                return;
+
+        s->n_failed_attempts  = (unsigned) -1;
+}
+
 static bool dns_server_grace_period_expired(DnsServer *s) {
         usec_t ts;
 

diff --git a/src/resolve/resolved-dns-server.h b/src/resolve/resolved-dns-server.h
index f82b14e8fb0718c4b41580249c272fa09fe2759d..a3e8cbcc52c5ebd789ff5047e2d41657d5c4c326 100644 (file)
--- a/src/resolve/resolved-dns-server.h
+++ b/src/resolve/resolved-dns-server.h
@@ -89,6 +89,7 @@ void dns_server_move_back_and_unmark(DnsServer *s);
 
 void dns_server_packet_received(DnsServer *s, DnsServerFeatureLevel features, usec_t rtt);
 void dns_server_packet_lost(DnsServer *s, DnsServerFeatureLevel features, usec_t usec);
+void dns_server_packet_failed(DnsServer *s, DnsServerFeatureLevel features);
 
 DnsServer *dns_server_find(DnsServer *first, int family, const union in_addr_union *in_addr);
 

diff --git a/src/resolve/resolved-dns-transaction.c b/src/resolve/resolved-dns-transaction.c
index 0e09a339aa40812c767b4aa57de0ed90ab12b6d9..4398c2cb9908cf43dc3fe256115d6aae97b8be06 100644 (file)
--- a/src/resolve/resolved-dns-transaction.c
+++ b/src/resolve/resolved-dns-transaction.c
@@ -418,7 +418,22 @@ void dns_transaction_process_reply(DnsTransaction *t, DnsPacket *p) {
         case DNS_PROTOCOL_DNS:
                 assert(t->server);
 
-                dns_server_packet_received(t->server, t->current_features, ts - t->start_usec);
+                if (IN_SET(DNS_PACKET_RCODE(p), DNS_RCODE_FORMERR, DNS_RCODE_SERVFAIL, DNS_RCODE_NOTIMP)) {
+
+                        /* request failed, immediately try again with reduced features */
+                        log_debug("Server returned error: %s", dns_rcode_to_string(DNS_PACKET_RCODE(p)));
+
+                        dns_server_packet_failed(t->server, t->current_features);
+
+                        r = dns_transaction_go(t);
+                        if (r < 0) {
+                                dns_transaction_complete(t, DNS_TRANSACTION_RESOURCES);
+                                return;
+                        }
+
+                        return;
+                } else
+                        dns_server_packet_received(t->server, t->current_features, ts - t->start_usec);
 
                 break;
         case DNS_PROTOCOL_LLMNR: