X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=src%2Fresolve%2Fresolved-dns-transaction.c;h=cf2987d1925cb4d922fc1e56f7e7e5e92a3ff240;hb=2fb3034cb21c745ed4f9aa4cba57563f7f071466;hp=ad1b277555254a4b92efff9520cda20a4750235d;hpb=13b551acb68695716cb4029531b5dec0759efa53;p=elogind.git

diff --git a/src/resolve/resolved-dns-transaction.c b/src/resolve/resolved-dns-transaction.c
index ad1b27755..cf2987d19 100644
--- a/src/resolve/resolved-dns-transaction.c
+++ b/src/resolve/resolved-dns-transaction.c
@@ -118,6 +118,7 @@ static void dns_transaction_stop(DnsTransaction *t) {
 }
 
 static void dns_transaction_tentative(DnsTransaction *t, DnsPacket *p) {
+        _cleanup_free_ char *pretty = NULL;
         DnsZoneItem *z;
         Iterator i;
 
@@ -127,10 +128,22 @@ static void dns_transaction_tentative(DnsTransaction *t, DnsPacket *p) {
         if (manager_our_packet(t->scope->manager, p) != 0)
                 return;
 
-        log_debug("Transaction on scope %s on %s/%s got tentative packet",
+        in_addr_to_string(p->family, &p->sender, &pretty);
+
+        log_debug("Transaction on scope %s on %s/%s got tentative packet from %s",
                   dns_protocol_to_string(t->scope->protocol),
                   t->scope->link ? t->scope->link->name : "*",
-                  t->scope->family == AF_UNSPEC ? "*" : af_to_name(t->scope->family));
+                  t->scope->family == AF_UNSPEC ? "*" : af_to_name(t->scope->family),
+                  pretty);
+
+        /* RFC 4795, Section 4.1 says that the peer with the
+         * lexicographically smaller IP address loses */
+        if (memcmp(&p->sender, &p->destination, FAMILY_ADDRESS_SIZE(p->family)) < 0) {
+                log_debug("Peer has lexicographically smaller IP address and thus lost in the conflict.");
+                return;
+        }
+
+        log_debug("We have the lexicographically smaller IP address and thus lost in the conflict.");
 
         t->block_gc++;
         SET_FOREACH(z, t->zone_items, i)
@@ -147,7 +160,9 @@ void dns_transaction_complete(DnsTransaction *t, DnsTransactionState state) {
 
         assert(t);
         assert(!IN_SET(state, DNS_TRANSACTION_NULL, DNS_TRANSACTION_PENDING));
-        assert(IN_SET(t->state, DNS_TRANSACTION_NULL, DNS_TRANSACTION_PENDING));
+
+        if (!IN_SET(t->state, DNS_TRANSACTION_NULL, DNS_TRANSACTION_PENDING))
+                return;
 
         /* Note that this call might invalidate the query. Callers
          * should hence not attempt to access the query or transaction
@@ -194,6 +209,14 @@ static int on_stream_complete(DnsStream *s, int error) {
                 return 0;
         }
 
+        if (dns_packet_validate_reply(p) <= 0) {
+                log_debug("Invalid LLMNR TCP packet.");
+                dns_transaction_complete(t, DNS_TRANSACTION_INVALID_REPLY);
+                return 0;
+        }
+
+        dns_scope_check_conflicts(t->scope, p);
+
         t->block_gc++;
         dns_transaction_process_reply(t, p);
         t->block_gc--;
@@ -368,7 +391,7 @@ void dns_transaction_process_reply(DnsTransaction *t, DnsPacket *p) {
         }
 
         /* According to RFC 4795, section 2.9. only the RRs from the answer section shall be cached */
-        dns_cache_put(&t->scope->cache, p->question, DNS_PACKET_RCODE(p), p->answer, DNS_PACKET_ANCOUNT(p), 0);
+        dns_cache_put(&t->scope->cache, p->question, DNS_PACKET_RCODE(p), p->answer, DNS_PACKET_ANCOUNT(p), 0, p->family, &p->sender);
 
         if (DNS_PACKET_RCODE(p) == DNS_RCODE_SUCCESS)
                 dns_transaction_complete(t, DNS_TRANSACTION_SUCCESS);
@@ -443,7 +466,7 @@ int dns_transaction_go(DnsTransaction *t) {
 
         dns_transaction_stop(t);
 
-        log_debug("Beginning transaction on scope %s on %s/%s",
+        log_debug("Excercising transaction on scope %s on %s/%s",
                   dns_protocol_to_string(t->scope->protocol),
                   t->scope->link ? t->scope->link->name : "*",
                   t->scope->family == AF_UNSPEC ? "*" : af_to_name(t->scope->family));
@@ -490,6 +513,34 @@ int dns_transaction_go(DnsTransaction *t) {
                 }
         }
 
+        if (t->scope->protocol == DNS_PROTOCOL_LLMNR && !t->initial_jitter) {
+                usec_t jitter;
+
+                /* RFC 4795 Section 2.7 suggests all queries should be
+                 * delayed by a random time from 0 to JITTER_INTERVAL. */
+
+                t->initial_jitter = true;
+
+                random_bytes(&jitter, sizeof(jitter));
+                jitter %= LLMNR_JITTER_INTERVAL_USEC;
+
+                r = sd_event_add_time(
+                                t->scope->manager->event,
+                                &t->timeout_event_source,
+                                clock_boottime_or_monotonic(),
+                                now(clock_boottime_or_monotonic()) + jitter,
+                                LLMNR_JITTER_INTERVAL_USEC,
+                                on_transaction_timeout, t);
+                if (r < 0)
+                        return r;
+
+                t->n_attempts = 0;
+                t->state = DNS_TRANSACTION_PENDING;
+
+                log_debug("Delaying LLMNR transaction for " USEC_FMT "us.", jitter);
+                return 0;
+        }
+
         log_debug("Cache miss!");
 
         /* Otherwise, we need to ask the network */
@@ -513,7 +564,7 @@ int dns_transaction_go(DnsTransaction *t) {
                 r = dns_transaction_open_tcp(t);
         } else {
                 /* Try via UDP, and if that fails due to large size try via TCP */
-                r = dns_scope_send(t->scope, t->sent);
+                r = dns_scope_emit(t->scope, t->sent);
                 if (r == -EMSGSIZE)
                         r = dns_transaction_open_tcp(t);
         }