X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=src%2Fresolve%2Fresolved-dns-query.c;h=f0483c98069f357b72f60a161842527ba8e369a2;hp=42f4f23cb98ee83a612eabf35584a68db9c14243;hb=56f64d95763a799ba4475daf44d8e9f72a1bd474;hpb=b914e211f3a40f507b3cdc572838ec7f3fd5e4cf

diff --git a/src/resolve/resolved-dns-query.c b/src/resolve/resolved-dns-query.c
index 42f4f23cb..f0483c980 100644
--- a/src/resolve/resolved-dns-query.c
+++ b/src/resolve/resolved-dns-query.c
@@ -19,484 +19,42 @@
   along with systemd; If not, see <http://www.gnu.org/licenses/>.
 ***/
 
+#include "af-list.h"
+
 #include "resolved-dns-query.h"
 #include "resolved-dns-domain.h"
 
-#define TRANSACTION_TIMEOUT_USEC (5 * USEC_PER_SEC)
+/* How long to wait for the query in total */
 #define QUERY_TIMEOUT_USEC (30 * USEC_PER_SEC)
-#define ATTEMPTS_MAX 8
+
 #define CNAME_MAX 8
 #define QUERIES_MAX 2048
 
-static int dns_query_transaction_go(DnsQueryTransaction *t);
-
-DnsQueryTransaction* dns_query_transaction_free(DnsQueryTransaction *t) {
-        DnsQuery *q;
-
-        if (!t)
-                return NULL;
-
-        sd_event_source_unref(t->timeout_event_source);
-
-        dns_question_unref(t->question);
-        dns_packet_unref(t->sent);
-        dns_packet_unref(t->received);
-        dns_answer_unref(t->cached);
-
-        dns_stream_free(t->stream);
-
-        if (t->scope) {
-                LIST_REMOVE(transactions_by_scope, t->scope->transactions, t);
-
-                if (t->id != 0)
-                        hashmap_remove(t->scope->manager->dns_query_transactions, UINT_TO_PTR(t->id));
-        }
-
-        while ((q = set_steal_first(t->queries)))
-                set_remove(q->transactions, t);
-
-        set_free(t->queries);
-
-        free(t);
-        return NULL;
-}
-
-DEFINE_TRIVIAL_CLEANUP_FUNC(DnsQueryTransaction*, dns_query_transaction_free);
-
-static void dns_query_transaction_gc(DnsQueryTransaction *t) {
-        assert(t);
-
-        if (t->block_gc > 0)
-                return;
-
-        if (set_isempty(t->queries))
-                dns_query_transaction_free(t);
-}
-
-static int dns_query_transaction_new(DnsQueryTransaction **ret, DnsScope *s, DnsQuestion *q) {
-        _cleanup_(dns_query_transaction_freep) DnsQueryTransaction *t = NULL;
-        int r;
+static void dns_query_stop(DnsQuery *q) {
+        DnsTransaction *t;
 
-        assert(ret);
-        assert(s);
         assert(q);
 
-        r = hashmap_ensure_allocated(&s->manager->dns_query_transactions, NULL, NULL);
-        if (r < 0)
-                return r;
-
-        t = new0(DnsQueryTransaction, 1);
-        if (!t)
-                return -ENOMEM;
-
-        t->question = dns_question_ref(q);
-
-        do
-                random_bytes(&t->id, sizeof(t->id));
-        while (t->id == 0 ||
-               hashmap_get(s->manager->dns_query_transactions, UINT_TO_PTR(t->id)));
-
-        r = hashmap_put(s->manager->dns_query_transactions, UINT_TO_PTR(t->id), t);
-        if (r < 0) {
-                t->id = 0;
-                return r;
-        }
-
-        LIST_PREPEND(transactions_by_scope, s->transactions, t);
-        t->scope = s;
-
-        if (ret)
-                *ret = t;
-
-        t = NULL;
-
-        return 0;
-}
-
-static void dns_query_transaction_stop(DnsQueryTransaction *t) {
-        assert(t);
-
-        t->timeout_event_source = sd_event_source_unref(t->timeout_event_source);
-        t->stream = dns_stream_free(t->stream);
-}
-
-void dns_query_transaction_complete(DnsQueryTransaction *t, DnsQueryState state) {
-        DnsQuery *q;
-        Iterator i;
-
-        assert(t);
-        assert(!IN_SET(state, DNS_QUERY_NULL, DNS_QUERY_PENDING));
-        assert(IN_SET(t->state, DNS_QUERY_NULL, DNS_QUERY_PENDING));
-
-        /* Note that this call might invalidate the query. Callers
-         * should hence not attempt to access the query or transaction
-         * after calling this function. */
-
-        t->state = state;
-
-        dns_query_transaction_stop(t);
-
-        /* Notify all queries that are interested, but make sure the
-         * transaction isn't freed while we are still looking at it */
-        t->block_gc++;
-        SET_FOREACH(q, t->queries, i)
-                dns_query_ready(q);
-        t->block_gc--;
-
-        dns_query_transaction_gc(t);
-}
-
-static int on_stream_complete(DnsStream *s, int error) {
-        _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
-        DnsQueryTransaction *t;
-
-        assert(s);
-        assert(s->transaction);
-
-        /* Copy the data we care about out of the stream before we
-         * destroy it. */
-        t = s->transaction;
-        p = dns_packet_ref(s->read_packet);
-
-        t->stream = dns_stream_free(t->stream);
-
-        if (error != 0) {
-                dns_query_transaction_complete(t, DNS_QUERY_RESOURCES);
-                return 0;
-        }
-
-        t->block_gc++;
-        dns_query_transaction_process_reply(t, p);
-        t->block_gc--;
-
-        /* If the response wasn't useful, then complete the transition now */
-        if (t->state == DNS_QUERY_PENDING)
-                dns_query_transaction_complete(t, DNS_QUERY_INVALID_REPLY);
-
-        return 0;
-}
-
-static int dns_query_transaction_open_tcp(DnsQueryTransaction *t) {
-        _cleanup_close_ int fd = -1;
-        int r;
-
-        assert(t);
-
-        if (t->stream)
-                return 0;
-
-        if (t->scope->protocol == DNS_PROTOCOL_DNS)
-                fd = dns_scope_tcp_socket(t->scope, AF_UNSPEC, NULL, 53);
-        else if (t->scope->protocol == DNS_PROTOCOL_LLMNR) {
-
-                /* When we already received a query to this (but it was truncated), send to its sender address */
-                if (t->received)
-                        fd = dns_scope_tcp_socket(t->scope, t->received->family, &t->received->sender, t->received->sender_port);
-                else {
-                        union in_addr_union address;
-                        int family;
-
-                        /* Otherwise, try to talk to the owner of a
-                         * the IP address, in case this is a reverse
-                         * PTR lookup */
-                        r = dns_question_extract_reverse_address(t->question, &family, &address);
-                        if (r < 0)
-                                return r;
-                        if (r == 0)
-                                return -EINVAL;
-
-                        fd = dns_scope_tcp_socket(t->scope, family, &address, 5355);
-                }
-        } else
-                return -EAFNOSUPPORT;
-
-        if (fd < 0)
-                return fd;
-
-        r = dns_stream_new(t->scope->manager, &t->stream, t->scope->protocol, fd);
-        if (r < 0)
-                return r;
-
-        fd = -1;
-
-        r = dns_stream_write_packet(t->stream, t->sent);
-        if (r < 0) {
-                t->stream = dns_stream_free(t->stream);
-                return r;
-        }
-
-        t->received = dns_packet_unref(t->received);
-        t->stream->complete = on_stream_complete;
-        t->stream->transaction = t;
-
-        /* The interface index is difficult to determine if we are
-         * connecting to the local host, hence fill this in right away
-         * instead of determining it from the socket */
-        if (t->scope->link)
-                t->stream->ifindex = t->scope->link->ifindex;
-
-        return 0;
-}
-
-void dns_query_transaction_process_reply(DnsQueryTransaction *t, DnsPacket *p) {
-        int r;
-
-        assert(t);
-        assert(p);
-        assert(t->state == DNS_QUERY_PENDING);
-
-        /* Note that this call might invalidate the query. Callers
-         * should hence not attempt to access the query or transaction
-         * after calling this function. */
-
-        if (t->scope->protocol == DNS_PROTOCOL_LLMNR) {
-                assert(t->scope->link);
-
-                /* For LLMNR we will not accept any packets from other
-                 * interfaces */
-
-                if (p->ifindex != t->scope->link->ifindex)
-                        return;
-
-                if (p->family != t->scope->family)
-                        return;
-
-                if (p->ipproto == IPPROTO_UDP) {
-                        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;
-                }
-        }
-
-        if (t->scope->protocol == DNS_PROTOCOL_DNS) {
-
-                /* For DNS we are fine with accepting packets on any
-                 * interface, but the source IP address must be one of
-                 * a valid DNS server */
-
-                if (!dns_scope_good_dns_server(t->scope, p->family, &p->sender))
-                        return;
-
-                if (p->sender_port != 53)
-                        return;
-        }
-
-        if (t->received != p) {
-                dns_packet_unref(t->received);
-                t->received = dns_packet_ref(p);
-        }
-
-        if (p->ipproto == IPPROTO_TCP) {
-                if (DNS_PACKET_TC(p)) {
-                        /* Truncated via TCP? Somebody must be fucking with us */
-                        dns_query_transaction_complete(t, DNS_QUERY_INVALID_REPLY);
-                        return;
-                }
-
-                if (DNS_PACKET_ID(p) != t->id) {
-                        /* Not the reply to our query? Somebody must be fucking with us */
-                        dns_query_transaction_complete(t, DNS_QUERY_INVALID_REPLY);
-                        return;
-                }
-        }
-
-        if (DNS_PACKET_TC(p)) {
-                /* Response was truncated, let's try again with good old TCP */
-                r = dns_query_transaction_open_tcp(t);
-                if (r == -ESRCH) {
-                        /* No servers found? Damn! */
-                        dns_query_transaction_complete(t, DNS_QUERY_NO_SERVERS);
-                        return;
-                }
-                if (r < 0) {
-                        /* On LLMNR, if we cannot connect to the host,
-                         * we immediately give up */
-                        if (t->scope->protocol == DNS_PROTOCOL_LLMNR) {
-                                dns_query_transaction_complete(t, DNS_QUERY_RESOURCES);
-                                return;
-                        }
-
-                        /* On DNS, couldn't send? Try immediately again, with a new server */
-                        dns_scope_next_dns_server(t->scope);
-
-                        r = dns_query_transaction_go(t);
-                        if (r < 0) {
-                                dns_query_transaction_complete(t, DNS_QUERY_RESOURCES);
-                                return;
-                        }
-
-                        return;
-                }
-        }
-
-        /* Parse and update the cache */
-        r = dns_packet_extract(p);
-        if (r < 0) {
-                dns_query_transaction_complete(t, DNS_QUERY_INVALID_REPLY);
-                return;
-        }
-
-        dns_cache_put(&t->scope->cache, p->question, DNS_PACKET_RCODE(p), p->answer, 0);
-
-        if (DNS_PACKET_RCODE(p) == DNS_RCODE_SUCCESS)
-                dns_query_transaction_complete(t, DNS_QUERY_SUCCESS);
-        else
-                dns_query_transaction_complete(t, DNS_QUERY_FAILURE);
-}
-
-static int on_transaction_timeout(sd_event_source *s, usec_t usec, void *userdata) {
-        DnsQueryTransaction *t = userdata;
-        int r;
-
-        assert(s);
-        assert(t);
-
-        /* Timeout reached? Try again, with a new server */
-        dns_scope_next_dns_server(t->scope);
-
-        r = dns_query_transaction_go(t);
-        if (r < 0)
-                dns_query_transaction_complete(t, DNS_QUERY_RESOURCES);
-
-        return 0;
-}
-
-static int dns_query_make_packet(DnsQueryTransaction *t) {
-        _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
-        unsigned n, added = 0;
-        int r;
-
-        assert(t);
-
-        if (t->sent)
-                return 0;
-
-        r = dns_packet_new_query(&p, t->scope->protocol, 0);
-        if (r < 0)
-                return r;
-
-        for (n = 0; n < t->question->n_keys; n++) {
-                r = dns_scope_good_key(t->scope, t->question->keys[n]);
-                if (r < 0)
-                        return r;
-                if (r == 0)
-                        continue;
-
-                r = dns_packet_append_key(p, t->question->keys[n], NULL);
-                if (r < 0)
-                        return r;
-
-                added++;
-        }
-
-        if (added <= 0)
-                return -EDOM;
-
-        DNS_PACKET_HEADER(p)->qdcount = htobe16(added);
-        DNS_PACKET_HEADER(p)->id = t->id;
-
-        t->sent = p;
-        p = NULL;
-
-        return 0;
-}
-
-static int dns_query_transaction_go(DnsQueryTransaction *t) {
-        int r;
-
-        assert(t);
-
-        dns_query_transaction_stop(t);
-
-        if (t->n_attempts >= ATTEMPTS_MAX) {
-                dns_query_transaction_complete(t, DNS_QUERY_ATTEMPTS_MAX);
-                return 0;
-        }
-
-        t->n_attempts++;
-        t->received = dns_packet_unref(t->received);
-        t->cached = dns_answer_unref(t->cached);
-        t->cached_rcode = 0;
-
-        /* First, let's try the cache */
-        dns_cache_prune(&t->scope->cache);
-        r = dns_cache_lookup(&t->scope->cache, t->question, &t->cached_rcode, &t->cached);
-        if (r < 0)
-                return r;
-        if (r > 0) {
-                if (t->cached_rcode == DNS_RCODE_SUCCESS)
-                        dns_query_transaction_complete(t, DNS_QUERY_SUCCESS);
-                else
-                        dns_query_transaction_complete(t, DNS_QUERY_FAILURE);
-                return 0;
-        }
-
-        /* Otherwise, we need to ask the network */
-        r = dns_query_make_packet(t);
-        if (r == -EDOM) {
-                /* Not the right request to make on this network?
-                 * (i.e. an A request made on IPv6 or an AAAA request
-                 * made on IPv4, on LLMNR or mDNS.) */
-                dns_query_transaction_complete(t, DNS_QUERY_NO_SERVERS);
-                return 0;
-        }
-        if (r < 0)
-                return r;
-
-        if (t->scope->protocol == DNS_PROTOCOL_LLMNR &&
-            (dns_question_endswith(t->question, "in-addr.arpa") > 0 ||
-             dns_question_endswith(t->question, "ip6.arpa") > 0)) {
-
-                /* RFC 4795, Section 2.4. says reverse lookups shall
-                 * always be made via TCP on LLMNR */
-                r = dns_query_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);
-                if (r == -EMSGSIZE)
-                        r = dns_query_transaction_open_tcp(t);
-        }
-        if (r == -ESRCH) {
-                /* No servers to send this to? */
-                dns_query_transaction_complete(t, DNS_QUERY_NO_SERVERS);
-                return 0;
-        }
-        if (r < 0) {
-                /* Couldn't send? Try immediately again, with a new server */
-                dns_scope_next_dns_server(t->scope);
+        q->timeout_event_source = sd_event_source_unref(q->timeout_event_source);
 
-                return dns_query_transaction_go(t);
+        while ((t = set_steal_first(q->transactions))) {
+                set_remove(t->queries, q);
+                dns_transaction_gc(t);
         }
-
-        r = sd_event_add_time(t->scope->manager->event, &t->timeout_event_source, CLOCK_MONOTONIC, now(CLOCK_MONOTONIC) + TRANSACTION_TIMEOUT_USEC, 0, on_transaction_timeout, t);
-        if (r < 0)
-                return r;
-
-        t->state = DNS_QUERY_PENDING;
-        return 1;
 }
 
 DnsQuery *dns_query_free(DnsQuery *q) {
-        DnsQueryTransaction *t;
-
         if (!q)
                 return NULL;
 
-        sd_bus_message_unref(q->request);
+        dns_query_stop(q);
+        set_free(q->transactions);
 
         dns_question_unref(q->question);
         dns_answer_unref(q->answer);
 
-        sd_event_source_unref(q->timeout_event_source);
-
-        while ((t = set_steal_first(q->transactions))) {
-                set_remove(t->queries, q);
-                dns_query_transaction_gc(t);
-        }
-
-        set_free(q->transactions);
+        sd_bus_message_unref(q->request);
+        sd_bus_track_unref(q->bus_track);
 
         if (q->manager) {
                 LIST_REMOVE(queries, q->manager->dns_queries, q);
@@ -508,7 +66,7 @@ DnsQuery *dns_query_free(DnsQuery *q) {
         return NULL;
 }
 
-int dns_query_new(Manager *m, DnsQuery **ret, DnsQuestion *question) {
+int dns_query_new(Manager *m, DnsQuery **ret, DnsQuestion *question, int ifindex, uint64_t flags) {
         _cleanup_(dns_query_freep) DnsQuery *q = NULL;
         unsigned i;
         int r;
@@ -528,12 +86,17 @@ int dns_query_new(Manager *m, DnsQuery **ret, DnsQuestion *question) {
                 return -ENOMEM;
 
         q->question = dns_question_ref(question);
+        q->ifindex = ifindex;
+        q->flags = flags;
 
         for (i = 0; i < question->n_keys; i++) {
-                log_debug("Looking up RR for %s %s %s",
-                          strna(dns_class_to_string(question->keys[i]->class)),
-                          strna(dns_type_to_string(question->keys[i]->type)),
-                          DNS_RESOURCE_KEY_NAME(question->keys[i]));
+                _cleanup_free_ char *p;
+
+                r = dns_resource_key_to_string(question->keys[i], &p);
+                if (r < 0)
+                        return r;
+
+                log_debug("Looking up RR for %s", p);
         }
 
         LIST_PREPEND(queries, m->dns_queries, q);
@@ -547,23 +110,10 @@ int dns_query_new(Manager *m, DnsQuery **ret, DnsQuestion *question) {
         return 0;
 }
 
-static void dns_query_stop(DnsQuery *q) {
-        DnsQueryTransaction *t;
-
-        assert(q);
-
-        q->timeout_event_source = sd_event_source_unref(q->timeout_event_source);
-
-        while ((t = set_steal_first(q->transactions))) {
-                set_remove(t->queries, q);
-                dns_query_transaction_gc(t);
-        }
-}
-
-static void dns_query_complete(DnsQuery *q, DnsQueryState state) {
+static void dns_query_complete(DnsQuery *q, DnsTransactionState state) {
         assert(q);
-        assert(!IN_SET(state, DNS_QUERY_NULL, DNS_QUERY_PENDING));
-        assert(IN_SET(q->state, DNS_QUERY_NULL, DNS_QUERY_PENDING));
+        assert(!IN_SET(state, DNS_TRANSACTION_NULL, DNS_TRANSACTION_PENDING));
+        assert(IN_SET(q->state, DNS_TRANSACTION_NULL, DNS_TRANSACTION_PENDING));
 
         /* Note that this call might invalidate the query. Callers
          * should hence not attempt to access the query or transaction
@@ -582,18 +132,19 @@ static int on_query_timeout(sd_event_source *s, usec_t usec, void *userdata) {
         assert(s);
         assert(q);
 
-        dns_query_complete(q, DNS_QUERY_TIMEOUT);
+        dns_query_complete(q, DNS_TRANSACTION_TIMEOUT);
         return 0;
 }
 
 static int dns_query_add_transaction(DnsQuery *q, DnsScope *s, DnsResourceKey *key) {
         _cleanup_(dns_question_unrefp) DnsQuestion *question = NULL;
-        DnsQueryTransaction *t;
+        DnsTransaction *t;
         int r;
 
         assert(q);
+        assert(s);
 
-        r = set_ensure_allocated(&q->transactions, NULL, NULL);
+        r = set_ensure_allocated(&q->transactions, NULL);
         if (r < 0)
                 return r;
 
@@ -608,34 +159,31 @@ static int dns_query_add_transaction(DnsQuery *q, DnsScope *s, DnsResourceKey *k
         } else
                 question = dns_question_ref(q->question);
 
-        LIST_FOREACH(transactions_by_scope, t, s->transactions)
-                if (dns_question_is_superset(t->question, question))
-                        break;
-
+        t = dns_scope_find_transaction(s, question, true);
         if (!t) {
-                r = dns_query_transaction_new(&t, s, question);
+                r = dns_transaction_new(&t, s, question);
                 if (r < 0)
                         return r;
         }
 
-        r = set_ensure_allocated(&t->queries, NULL, NULL);
+        r = set_ensure_allocated(&t->queries, NULL);
         if (r < 0)
-                goto fail;
+                goto gc;
 
         r = set_put(t->queries, q);
         if (r < 0)
-                goto fail;
+                goto gc;
 
         r = set_put(q->transactions, t);
         if (r < 0) {
                 set_remove(t->queries, q);
-                goto fail;
+                goto gc;
         }
 
         return 0;
 
-fail:
-        dns_query_transaction_gc(t);
+gc:
+        dns_transaction_gc(t);
         return r;
 }
 
@@ -669,14 +217,14 @@ static int dns_query_add_transaction_split(DnsQuery *q, DnsScope *s) {
 int dns_query_go(DnsQuery *q) {
         DnsScopeMatch found = DNS_SCOPE_NO;
         DnsScope *s, *first = NULL;
-        DnsQueryTransaction *t;
+        DnsTransaction *t;
         const char *name;
         Iterator i;
         int r;
 
         assert(q);
 
-        if (q->state != DNS_QUERY_NULL)
+        if (q->state != DNS_TRANSACTION_NULL)
                 return 0;
 
         assert(q->question);
@@ -687,7 +235,7 @@ int dns_query_go(DnsQuery *q) {
         LIST_FOREACH(scopes, s, q->manager->dns_scopes) {
                 DnsScopeMatch match;
 
-                match = dns_scope_good_domain(s, name);
+                match = dns_scope_good_domain(s, q->ifindex, q->flags, name);
                 if (match < 0)
                         return match;
 
@@ -712,40 +260,49 @@ int dns_query_go(DnsQuery *q) {
 
         r = dns_query_add_transaction_split(q, first);
         if (r < 0)
-                return r;
+                goto fail;
 
         LIST_FOREACH(scopes, s, first->scopes_next) {
                 DnsScopeMatch match;
 
-                match = dns_scope_good_domain(s, name);
+                match = dns_scope_good_domain(s, q->ifindex, q->flags, name);
                 if (match < 0)
-                        return match;
+                        goto fail;
 
                 if (match != found)
                         continue;
 
                 r = dns_query_add_transaction_split(q, s);
                 if (r < 0)
-                        return r;
+                        goto fail;
         }
 
         q->answer = dns_answer_unref(q->answer);
         q->answer_ifindex = 0;
         q->answer_rcode = 0;
-
-        r = sd_event_add_time(q->manager->event, &q->timeout_event_source, CLOCK_MONOTONIC, now(CLOCK_MONOTONIC) + QUERY_TIMEOUT_USEC, 0, on_query_timeout, q);
+        q->answer_family = AF_UNSPEC;
+        q->answer_protocol = _DNS_PROTOCOL_INVALID;
+
+        r = sd_event_add_time(
+                        q->manager->event,
+                        &q->timeout_event_source,
+                        clock_boottime_or_monotonic(),
+                        now(clock_boottime_or_monotonic()) + QUERY_TIMEOUT_USEC, 0,
+                        on_query_timeout, q);
         if (r < 0)
                 goto fail;
 
-        q->state = DNS_QUERY_PENDING;
+        q->state = DNS_TRANSACTION_PENDING;
         q->block_ready++;
 
+        /* Start the transactions that are not started yet */
         SET_FOREACH(t, q->transactions, i) {
-                if (t->state == DNS_QUERY_NULL) {
-                        r = dns_query_transaction_go(t);
-                        if (r < 0)
-                                goto fail;
-                }
+                if (t->state != DNS_TRANSACTION_NULL)
+                        continue;
+
+                r = dns_transaction_go(t);
+                if (r < 0)
+                        goto fail;
         }
 
         q->block_ready--;
@@ -759,15 +316,16 @@ fail:
 }
 
 void dns_query_ready(DnsQuery *q) {
-        DnsQueryTransaction *t;
-        DnsQueryState state = DNS_QUERY_NO_SERVERS;
+        DnsTransaction *t;
+        DnsTransactionState state = DNS_TRANSACTION_NO_SERVERS;
         _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
         int rcode = 0;
         DnsScope *scope = NULL;
+        bool pending = false;
         Iterator i;
 
         assert(q);
-        assert(IN_SET(q->state, DNS_QUERY_NULL, DNS_QUERY_PENDING));
+        assert(IN_SET(q->state, DNS_TRANSACTION_NULL, DNS_TRANSACTION_PENDING));
 
         /* Note that this call might invalidate the query. Callers
          * should hence not attempt to access the query or transaction
@@ -780,16 +338,18 @@ void dns_query_ready(DnsQuery *q) {
         SET_FOREACH(t, q->transactions, i) {
 
                 /* If we found a successful answer, ignore all answers from other scopes */
-                if (state == DNS_QUERY_SUCCESS && t->scope != scope)
+                if (state == DNS_TRANSACTION_SUCCESS && t->scope != scope)
                         continue;
 
-                /* One of the transactions is still going on, let's wait for it */
-                if (t->state == DNS_QUERY_PENDING || t->state == DNS_QUERY_NULL)
-                        return;
+                /* One of the transactions is still going on, let's maybe wait for it */
+                if (IN_SET(t->state, DNS_TRANSACTION_PENDING, DNS_TRANSACTION_NULL)) {
+                        pending = true;
+                        continue;
+                }
 
                 /* One of the transactions is successful, let's use
                  * it, and copy its data out */
-                if (t->state == DNS_QUERY_SUCCESS) {
+                if (t->state == DNS_TRANSACTION_SUCCESS) {
                         DnsAnswer *a;
 
                         if (t->received) {
@@ -800,12 +360,12 @@ void dns_query_ready(DnsQuery *q) {
                                 a = t->cached;
                         }
 
-                        if (state == DNS_QUERY_SUCCESS) {
+                        if (state == DNS_TRANSACTION_SUCCESS) {
                                 DnsAnswer *merged;
 
                                 merged = dns_answer_merge(answer, a);
                                 if (!merged) {
-                                        dns_query_complete(q, DNS_QUERY_RESOURCES);
+                                        dns_query_complete(q, DNS_TRANSACTION_RESOURCES);
                                         return;
                                 }
 
@@ -817,14 +377,14 @@ void dns_query_ready(DnsQuery *q) {
                         }
 
                         scope = t->scope;
-                        state = DNS_QUERY_SUCCESS;
+                        state = DNS_TRANSACTION_SUCCESS;
                         continue;
                 }
 
                 /* One of the transactions has failed, let's see
                  * whether we find anything better, but if not, return
                  * its response data */
-                if (state != DNS_QUERY_SUCCESS && t->state == DNS_QUERY_FAILURE) {
+                if (state != DNS_TRANSACTION_SUCCESS && t->state == DNS_TRANSACTION_FAILURE) {
                         DnsAnswer *a;
 
                         if (t->received) {
@@ -839,18 +399,35 @@ void dns_query_ready(DnsQuery *q) {
                         answer = dns_answer_ref(a);
 
                         scope = t->scope;
-                        state = DNS_QUERY_FAILURE;
+                        state = DNS_TRANSACTION_FAILURE;
                         continue;
                 }
 
-                if (state == DNS_QUERY_NO_SERVERS && t->state != DNS_QUERY_NO_SERVERS)
+                if (state == DNS_TRANSACTION_NO_SERVERS && t->state != DNS_TRANSACTION_NO_SERVERS)
                         state = t->state;
         }
 
-        if (IN_SET(state, DNS_QUERY_SUCCESS, DNS_QUERY_FAILURE)) {
+        if (pending) {
+
+                /* If so far we weren't successful, and there's
+                 * something still pending, then wait for it */
+                if (state != DNS_TRANSACTION_SUCCESS)
+                        return;
+
+                /* If we already were successful, then only wait for
+                 * other transactions on the same scope to finish. */
+                SET_FOREACH(t, q->transactions, i) {
+                        if (t->scope == scope && IN_SET(t->state, DNS_TRANSACTION_PENDING, DNS_TRANSACTION_NULL))
+                                return;
+                }
+        }
+
+        if (IN_SET(state, DNS_TRANSACTION_SUCCESS, DNS_TRANSACTION_FAILURE)) {
                 q->answer = dns_answer_ref(answer);
                 q->answer_rcode = rcode;
                 q->answer_ifindex = (scope && scope->link) ? scope->link->ifindex : 0;
+                q->answer_protocol = scope ? scope->protocol : _DNS_PROTOCOL_INVALID;
+                q->answer_family = scope ? scope->family : AF_UNSPEC;
         }
 
         dns_query_complete(q, state);
@@ -876,7 +453,37 @@ int dns_query_cname_redirect(DnsQuery *q, const char *name) {
         q->n_cname_redirects++;
 
         dns_query_stop(q);
-        q->state = DNS_QUERY_NULL;
+        q->state = DNS_TRANSACTION_NULL;
+
+        return 0;
+}
+
+static int on_bus_track(sd_bus_track *t, void *userdata) {
+        DnsQuery *q = userdata;
+
+        assert(t);
+        assert(q);
+
+        log_debug("Client of active query vanished, aborting query.");
+        dns_query_complete(q, DNS_TRANSACTION_ABORTED);
+        return 0;
+}
+
+int dns_query_bus_track(DnsQuery *q, sd_bus *bus, sd_bus_message *m) {
+        int r;
+
+        assert(q);
+        assert(m);
+
+        if (!q->bus_track) {
+                r = sd_bus_track_new(bus, &q->bus_track, on_bus_track, q);
+                if (r < 0)
+                        return r;
+        }
+
+        r = sd_bus_track_add_sender(q->bus_track, m);
+        if (r < 0)
+                return r;
 
         return 0;
 }