chiark / gitweb /
resolved: add DNS cache
[elogind.git] / src / resolve / resolved-dns-query.c
index a9880524e617f7bb6e5345ffd3dc84345cc661ca..3955bc2d7b04e2afd47003bca395c4aa82ac2cda 100644 (file)
 #define TRANSACTION_TIMEOUT_USEC (5 * USEC_PER_SEC)
 #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) {
         if (!t)
                 return NULL;
 
         sd_event_source_unref(t->timeout_event_source);
-        dns_packet_unref(t->packet);
+
+        dns_packet_unref(t->sent);
+        dns_packet_unref(t->received);
+
+        dns_resource_record_freev(t->cached_rrs, t->n_cached_rrs);
+
+        sd_event_source_unref(t->tcp_event_source);
+        safe_close(t->tcp_fd);
 
         if (t->query) {
                 LIST_REMOVE(transactions_by_query, t->query->transactions, t);
@@ -62,6 +73,8 @@ static int dns_query_transaction_new(DnsQuery *q, DnsQueryTransaction **ret, Dns
         if (!t)
                 return -ENOMEM;
 
+        t->tcp_fd = -1;
+
         do
                 random_bytes(&t->id, sizeof(t->id));
         while (t->id == 0 ||
@@ -87,37 +100,221 @@ static int dns_query_transaction_new(DnsQuery *q, DnsQueryTransaction **ret, Dns
         return 0;
 }
 
-static void dns_query_transaction_set_state(DnsQueryTransaction *t, DnsQueryState state) {
+static void dns_query_transaction_stop(DnsQueryTransaction *t) {
         assert(t);
 
-        if (t->state == state)
-                return;
+        t->timeout_event_source = sd_event_source_unref(t->timeout_event_source);
+        t->tcp_event_source = sd_event_source_unref(t->tcp_event_source);
+        t->tcp_fd = safe_close(t->tcp_fd);
+}
 
-        t->state = state;
+static void dns_query_transaction_complete(DnsQueryTransaction *t, DnsQueryState state) {
+        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. */
 
-        if (state != DNS_QUERY_SENT)
-                t->timeout_event_source = sd_event_source_unref(t->timeout_event_source);
+        t->state = state;
 
+        dns_query_transaction_stop(t);
         dns_query_finish(t->query);
 }
 
-int dns_query_transaction_reply(DnsQueryTransaction *t, DnsPacket *p) {
+static int on_tcp_ready(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
+        DnsQueryTransaction *t = userdata;
+        int r;
+
         assert(t);
-        assert(p);
 
-        t->packet = dns_packet_ref(p);
+        if (revents & EPOLLOUT) {
+                struct iovec iov[2];
+                be16_t sz;
+                ssize_t ss;
+
+                sz = htobe16(t->sent->size);
+
+                iov[0].iov_base = &sz;
+                iov[0].iov_len = sizeof(sz);
+                iov[1].iov_base = DNS_PACKET_DATA(t->sent);
+                iov[1].iov_len = t->sent->size;
+
+                IOVEC_INCREMENT(iov, 2, t->tcp_written);
+
+                ss = writev(fd, iov, 2);
+                if (ss < 0) {
+                        if (errno != EINTR && errno != EAGAIN) {
+                                dns_query_transaction_complete(t, DNS_QUERY_RESOURCES);
+                                return -errno;
+                        }
+                } else
+                        t->tcp_written += ss;
+
+                /* Are we done? If so, disable the event source for EPOLLOUT */
+                if (t->tcp_written >= sizeof(sz) + t->sent->size) {
+                        r = sd_event_source_set_io_events(s, EPOLLIN);
+                        if (r < 0) {
+                                dns_query_transaction_complete(t, DNS_QUERY_RESOURCES);
+                                return r;
+                        }
+                }
+        }
 
-        if (DNS_PACKET_RCODE(p) == DNS_RCODE_SUCCESS) {
-                if( be16toh(DNS_PACKET_HEADER(p)->ancount) > 0)
-                        dns_query_transaction_set_state(t, DNS_QUERY_SUCCESS);
-                else
-                        dns_query_transaction_set_state(t, DNS_QUERY_INVALID_REPLY);
-        } else
-                dns_query_transaction_set_state(t, DNS_QUERY_FAILURE);
+        if (revents & (EPOLLIN|EPOLLHUP|EPOLLRDHUP)) {
+
+                if (t->tcp_read < sizeof(t->tcp_read_size)) {
+                        ssize_t ss;
+
+                        ss = read(fd, (uint8_t*) &t->tcp_read_size + t->tcp_read, sizeof(t->tcp_read_size) - t->tcp_read);
+                        if (ss < 0) {
+                                if (errno != EINTR && errno != EAGAIN) {
+                                        dns_query_transaction_complete(t, DNS_QUERY_RESOURCES);
+                                        return -errno;
+                                }
+                        } else if (ss == 0) {
+                                dns_query_transaction_complete(t, DNS_QUERY_RESOURCES);
+                                return -EIO;
+                        } else
+                                t->tcp_read += ss;
+                }
+
+                if (t->tcp_read >= sizeof(t->tcp_read_size)) {
+
+                        if (be16toh(t->tcp_read_size) < DNS_PACKET_HEADER_SIZE) {
+                                dns_query_transaction_complete(t, DNS_QUERY_INVALID_REPLY);
+                                return -EBADMSG;
+                        }
+
+                        if (t->tcp_read < sizeof(t->tcp_read_size) + be16toh(t->tcp_read_size)) {
+                                ssize_t ss;
+
+                                if (!t->received) {
+                                        r = dns_packet_new(&t->received, be16toh(t->tcp_read_size));
+                                        if (r < 0) {
+                                                dns_query_transaction_complete(t, DNS_QUERY_RESOURCES);
+                                                return r;
+                                        }
+                                }
+
+                                ss = read(fd,
+                                          (uint8_t*) DNS_PACKET_DATA(t->received) + t->tcp_read - sizeof(t->tcp_read_size),
+                                          sizeof(t->tcp_read_size) + be16toh(t->tcp_read_size) - t->tcp_read);
+                                if (ss < 0) {
+                                        if (errno != EINTR && errno != EAGAIN) {
+                                                dns_query_transaction_complete(t, DNS_QUERY_RESOURCES);
+                                                return -errno;
+                                        }
+                                } else if (ss == 0) {
+                                        dns_query_transaction_complete(t, DNS_QUERY_RESOURCES);
+                                        return -EIO;
+                                }  else
+                                        t->tcp_read += ss;
+                        }
+
+                        if (t->tcp_read >= sizeof(t->tcp_read_size) + be16toh(t->tcp_read_size)) {
+                                t->received->size = be16toh(t->tcp_read_size);
+                                dns_query_transaction_reply(t, t->received);
+                                return 0;
+                        }
+                }
+        }
 
         return 0;
 }
 
+static int dns_query_transaction_open_tcp(DnsQueryTransaction *t) {
+        int r;
+
+        assert(t);
+
+        if (t->tcp_fd >= 0)
+                return 0;
+
+        t->tcp_written = 0;
+        t->tcp_read = 0;
+        t->received = dns_packet_unref(t->received);
+
+        t->tcp_fd = dns_scope_tcp_socket(t->scope);
+        if (t->tcp_fd < 0)
+                return t->tcp_fd;
+
+        r = sd_event_add_io(t->query->manager->event, &t->tcp_event_source, t->tcp_fd, EPOLLIN|EPOLLOUT, on_tcp_ready, t);
+        if (r < 0) {
+                t->tcp_fd = safe_close(t->tcp_fd);
+                return r;
+        }
+
+        return 0;
+}
+
+void dns_query_transaction_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->received != p) {
+                dns_packet_unref(t->received);
+                t->received = dns_packet_ref(p);
+        }
+
+        if (t->tcp_fd >= 0) {
+                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) {
+                        /* 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_rrs(p);
+        if (r < 0) {
+                dns_query_transaction_complete(t, DNS_QUERY_INVALID_REPLY);
+                return;
+        } else if (r > 0)
+                dns_cache_put_rrs(&t->scope->cache, p->rrs, r, 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;
@@ -128,28 +325,22 @@ static int on_transaction_timeout(sd_event_source *s, usec_t usec, void *userdat
         /* Timeout reached? Try again, with a new server */
         dns_scope_next_dns_server(t->scope);
 
-        r = dns_query_transaction_start(t);
+        r = dns_query_transaction_go(t);
         if (r < 0)
-                dns_query_transaction_set_state(t, DNS_QUERY_FAILURE);
+                dns_query_transaction_complete(t, DNS_QUERY_RESOURCES);
 
         return 0;
 }
 
-int dns_query_transaction_start(DnsQueryTransaction *t) {
+static int dns_query_make_packet(DnsQueryTransaction *t) {
         _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
         unsigned n;
         int r;
 
         assert(t);
 
-        t->timeout_event_source = sd_event_source_unref(t->timeout_event_source);
-
-        if (t->n_attempts >= ATTEMPTS_MAX) {
-                dns_query_transaction_set_state(t, DNS_QUERY_ATTEMPTS_MAX);
+        if (t->sent)
                 return 0;
-        }
-
-        t->n_attempts++;
 
         r = dns_packet_new_query(&p, 0);
         if (r < 0)
@@ -164,26 +355,66 @@ int dns_query_transaction_start(DnsQueryTransaction *t) {
         DNS_PACKET_HEADER(p)->qdcount = htobe16(t->query->n_keys);
         DNS_PACKET_HEADER(p)->id = t->id;
 
-        r = dns_scope_send(t->scope, p);
-        if (r < 0) {
-                /* Couldn't send? Try immediately again, with a new server */
-                dns_scope_next_dns_server(t->scope);
+        t->sent = p;
+        p = NULL;
 
-                return dns_query_transaction_start(t);
+        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_rrs = dns_resource_record_freev(t->cached_rrs, t->n_cached_rrs);
+        t->n_cached_rrs = 0;
+
+        /* First, let's try the cache */
+        dns_cache_prune(&t->scope->cache);
+        r = dns_cache_lookup_many(&t->scope->cache, t->query->keys, t->query->n_keys, &t->cached_rrs);
+        if (r < 0)
+                return r;
         if (r > 0) {
-                int q;
+                t->n_cached_rrs = r;
+                dns_query_transaction_complete(t, DNS_QUERY_SUCCESS);
+                return 0;
+        }
 
-                q = sd_event_add_time(t->query->manager->event, &t->timeout_event_source, CLOCK_MONOTONIC, now(CLOCK_MONOTONIC) + TRANSACTION_TIMEOUT_USEC, 0, on_transaction_timeout, t);
-                if (q < 0)
-                        return q;
+        /* Otherwise, we need to ask the network */
+        r = dns_query_make_packet(t);
+        if (r < 0)
+                return r;
 
-                dns_query_transaction_set_state(t, DNS_QUERY_SENT);
-        } else
-                dns_query_transaction_set_state(t, DNS_QUERY_SKIPPED);
+        /* 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) {
+                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);
 
-        return r;
+                return dns_query_transaction_go(t);
+        }
+
+        r = sd_event_add_time(t->query->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) {
@@ -193,14 +424,19 @@ DnsQuery *dns_query_free(DnsQuery *q) {
                 return NULL;
 
         sd_bus_message_unref(q->request);
-        dns_packet_unref(q->packet);
+        dns_packet_unref(q->received);
+
+        dns_resource_record_freev(q->cached_rrs, q->n_cached_rrs);
+
         sd_event_source_unref(q->timeout_event_source);
 
         while (q->transactions)
                 dns_query_transaction_free(q->transactions);
 
-        if (q->manager)
+        if (q->manager) {
                 LIST_REMOVE(queries, q->manager->dns_queries, q);
+                q->manager->n_dns_queries--;
+        }
 
         for (n = 0; n < q->n_keys; n++)
                 free(q->keys[n].name);
@@ -212,16 +448,16 @@ DnsQuery *dns_query_free(DnsQuery *q) {
 
 int dns_query_new(Manager *m, DnsQuery **ret, DnsResourceKey *keys, unsigned n_keys) {
         _cleanup_(dns_query_freep) DnsQuery *q = NULL;
-        DnsScope *s, *first = NULL;
-        DnsScopeMatch found = DNS_SCOPE_NO;
         const char *name = NULL;
-        int n, r;
 
         assert(m);
 
         if (n_keys <= 0 || n_keys >= 65535)
                 return -EINVAL;
 
+        if (m->n_dns_queries >= QUERIES_MAX)
+                return -EBUSY;
+
         assert(keys);
 
         q = new0(DnsQuery, 1);
@@ -243,15 +479,76 @@ int dns_query_new(Manager *m, DnsQuery **ret, DnsResourceKey *keys, unsigned n_k
                         name = q->keys[q->n_keys].name;
                 else if (!dns_name_equal(name, q->keys[q->n_keys].name))
                         return -EINVAL;
+
+                log_debug("Looking up RR for %s %s %s",
+                          strna(dns_class_to_string(keys[q->n_keys].class)),
+                          strna(dns_type_to_string(keys[q->n_keys].type)),
+                          keys[q->n_keys].name);
         }
 
         LIST_PREPEND(queries, m->dns_queries, q);
+        m->n_dns_queries++;
         q->manager = m;
 
-        LIST_FOREACH(scopes, s, m->dns_scopes) {
+        if (ret)
+                *ret = q;
+        q = NULL;
+
+        return 0;
+}
+
+static void dns_query_stop(DnsQuery *q) {
+        assert(q);
+
+        q->timeout_event_source = sd_event_source_unref(q->timeout_event_source);
+
+        while (q->transactions)
+                dns_query_transaction_free(q->transactions);
+}
+
+static void dns_query_complete(DnsQuery *q, DnsQueryState state) {
+        assert(q);
+        assert(!IN_SET(state, DNS_QUERY_NULL, DNS_QUERY_PENDING));
+        assert(IN_SET(q->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. */
+
+        q->state = state;
+
+        dns_query_stop(q);
+        if (q->complete)
+                q->complete(q);
+}
+
+static int on_query_timeout(sd_event_source *s, usec_t usec, void *userdata) {
+        DnsQuery *q = userdata;
+
+        assert(s);
+        assert(q);
+
+        dns_query_complete(q, DNS_QUERY_TIMEOUT);
+        return 0;
+}
+
+int dns_query_go(DnsQuery *q) {
+        DnsScopeMatch found = DNS_SCOPE_NO;
+        DnsScope *s, *first = NULL;
+        DnsQueryTransaction *t;
+        int r;
+
+        assert(q);
+
+        if (q->state != DNS_QUERY_NULL)
+                return 0;
+
+        assert(q->n_keys > 0);
+
+        LIST_FOREACH(scopes, s, q->manager->dns_scopes) {
                 DnsScopeMatch match;
 
-                match = dns_scope_test(s, name);
+                match = dns_scope_test(s, q->keys[0].name);
                 if (match < 0)
                         return match;
 
@@ -272,17 +569,16 @@ int dns_query_new(Manager *m, DnsQuery **ret, DnsResourceKey *keys, unsigned n_k
         }
 
         if (found == DNS_SCOPE_NO)
-                return -ENETDOWN;
+                return -ESRCH;
 
         r = dns_query_transaction_new(q, NULL, first);
         if (r < 0)
                 return r;
 
-        n = 1;
         LIST_FOREACH(scopes, s, first->scopes_next) {
                 DnsScopeMatch match;
 
-                match = dns_scope_test(s, name);
+                match = dns_scope_test(s, q->keys[0].name);
                 if (match < 0)
                         return match;
 
@@ -292,117 +588,226 @@ int dns_query_new(Manager *m, DnsQuery **ret, DnsResourceKey *keys, unsigned n_k
                 r = dns_query_transaction_new(q, NULL, s);
                 if (r < 0)
                         return r;
+        }
 
-                n++;
+        q->received = dns_packet_unref(q->received);
+
+        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);
+        if (r < 0)
+                goto fail;
+
+        q->state = DNS_QUERY_PENDING;
+        q->block_finish++;
+
+        LIST_FOREACH(transactions_by_query, t, q->transactions) {
+                r = dns_query_transaction_go(t);
+                if (r < 0)
+                        goto fail;
         }
 
-        if (ret)
-                *ret = q;
-        q = NULL;
+        q->block_finish--;
+        dns_query_finish(q);
+
+        return 1;
 
-        return n;
+fail:
+        dns_query_stop(q);
+        return r;
 }
 
-static void dns_query_set_state(DnsQuery *q, DnsQueryState state) {
+void dns_query_finish(DnsQuery *q) {
+        DnsQueryTransaction *t;
+        DnsQueryState state = DNS_QUERY_NO_SERVERS;
+        DnsPacket *received = NULL;
+
         assert(q);
+        assert(IN_SET(q->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, unless the block_finish
+         * counter was explicitly bumped before doing so. */
 
-        if (q->state == state)
+        if (q->block_finish > 0)
                 return;
 
-        q->state = state;
+        LIST_FOREACH(transactions_by_query, t, q->transactions) {
 
-        if (state == DNS_QUERY_SENT)
-                return;
+                /* 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;
 
-        q->timeout_event_source = sd_event_source_unref(q->timeout_event_source);
+                /* One of the transactions is successful, let's use
+                 * it, and copy its data out */
+                if (t->state == DNS_QUERY_SUCCESS) {
+                        q->received = dns_packet_ref(t->received);
 
-        while (q->transactions)
-                dns_query_transaction_free(q->transactions);
+                        /* We simply steal the cached RRs array */
+                        q->cached_rrs = t->cached_rrs;
+                        q->n_cached_rrs = t->n_cached_rrs;
+                        t->cached_rrs = NULL;
+                        t->n_cached_rrs = 0;
 
-        if (q->complete)
-                q->complete(q);
+                        dns_query_complete(q, DNS_QUERY_SUCCESS);
+                        return;
+                }
+
+                /* One of the transactions has failed, let's see
+                 * whether we find anything better, but if not, return
+                 * its response packet */
+                if (t->state == DNS_QUERY_FAILURE) {
+                        received = t->received;
+                        state = DNS_QUERY_FAILURE;
+                        continue;
+                }
+
+                if (state == DNS_QUERY_NO_SERVERS && t->state != DNS_QUERY_NO_SERVERS)
+                        state = t->state;
+        }
+
+        if (state == DNS_QUERY_FAILURE)
+                q->received = dns_packet_ref(received);
+
+        dns_query_complete(q, state);
 }
 
-static int on_query_timeout(sd_event_source *s, usec_t usec, void *userdata) {
-        DnsQuery *q = userdata;
+int dns_query_cname_redirect(DnsQuery *q, const char *name) {
+        DnsResourceKey *keys;
+        unsigned i;
 
-        assert(s);
         assert(q);
 
-        dns_query_set_state(q, DNS_QUERY_TIMEOUT);
+        if (q->n_cname > CNAME_MAX)
+                return -ELOOP;
+
+        keys = new(DnsResourceKey, q->n_keys);
+        if (!keys)
+                return -ENOMEM;
+
+        for (i = 0; i < q->n_keys; i++) {
+                keys[i].class = q->keys[i].class;
+                keys[i].type = q->keys[i].type;
+                keys[i].name = strdup(name);
+                if (!keys[i].name) {
+
+                        for (; i > 0; i--)
+                                free(keys[i-1].name);
+                        free(keys);
+                        return -ENOMEM;
+                }
+        }
+
+        for (i = 0; i < q->n_keys; i++)
+                free(q->keys[i].name);
+        free(q->keys);
+
+        q->keys = keys;
+
+        q->n_cname++;
+
+        dns_query_stop(q);
+        q->state = DNS_QUERY_NULL;
+
         return 0;
 }
 
-int dns_query_start(DnsQuery *q) {
-        DnsQueryTransaction *t;
+int dns_query_matches_rr(DnsQuery *q, DnsResourceRecord *rr) {
+        unsigned i;
         int r;
 
         assert(q);
-        assert(q->state == DNS_QUERY_NULL);
+        assert(rr);
 
-        if (!q->transactions)
-                return -ENETDOWN;
+        for (i = 0; i < q->n_keys; i++) {
 
-        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);
-        if (r < 0)
-                goto fail;
-
-        dns_query_set_state(q, DNS_QUERY_SENT);
-
-        LIST_FOREACH(transactions_by_query, t, q->transactions) {
+                if (rr->key.class != q->keys[i].class)
+                        continue;
 
-                r = dns_query_transaction_start(t);
-                if (r < 0)
-                        goto fail;
+                if (rr->key.type != q->keys[i].type &&
+                    q->keys[i].type != DNS_TYPE_ANY)
+                        continue;
 
-                if (q->state != DNS_QUERY_SENT)
-                        break;
+                r = dns_name_equal(rr->key.name, q->keys[i].name);
+                if (r != 0)
+                        return r;
         }
 
         return 0;
+}
 
-fail:
-        while (q->transactions)
-                dns_query_transaction_free(q->transactions);
+int dns_query_matches_cname(DnsQuery *q, DnsResourceRecord *rr) {
+        unsigned i;
+        int r;
 
-        return r;
+        assert(q);
+        assert(rr);
+
+        for (i = 0; i < q->n_keys; i++) {
+
+                if (rr->key.class != q->keys[i].class)
+                        continue;
+
+                if (rr->key.type != DNS_TYPE_CNAME)
+                        continue;
+
+                r = dns_name_equal(rr->key.name, q->keys[i].name);
+                if (r != 0)
+                        return r;
+        }
+
+        return 0;
 }
 
-void dns_query_finish(DnsQuery *q) {
-        DnsQueryTransaction *t;
-        DnsQueryState state = DNS_QUERY_SKIPPED;
-        uint16_t rcode = 0;
+int dns_query_get_rrs(DnsQuery *q, DnsResourceRecord ***rrs) {
+        int r;
 
         assert(q);
+        assert(rrs);
 
-        if (q->state != DNS_QUERY_SENT)
-                return;
+        if (IN_SET(q->state, DNS_QUERY_NULL, DNS_QUERY_PENDING))
+                return -EBUSY;
 
-        LIST_FOREACH(transactions_by_query, t, q->transactions) {
+        if (q->received) {
+                r = dns_packet_extract_rrs(q->received);
+                if (r < 0)
+                        return r;
+                if (r == 0) {
+                        *rrs = NULL;
+                        return r;
+                }
 
-                /* One of the transactions is still going on, let's wait for it */
-                if (t->state == DNS_QUERY_SENT || t->state == DNS_QUERY_NULL)
-                        return;
+                *rrs = q->received->rrs;
+                return r;
+        }
 
-                /* One of the transactions is sucecssful, let's use it */
-                if (t->state == DNS_QUERY_SUCCESS) {
-                        q->packet = dns_packet_ref(t->packet);
-                        dns_query_set_state(q, DNS_QUERY_SUCCESS);
-                        return;
-                }
+        if (q->cached_rrs) {
+                *rrs = q->cached_rrs;
+                return q->n_cached_rrs;
+        }
 
-                if (t->state == DNS_QUERY_FAILURE) {
-                        state = DNS_QUERY_FAILURE;
+        return -ESRCH;
+}
 
-                        if (rcode == 0 && t->packet)
-                                rcode = DNS_PACKET_RCODE(t->packet);
+int dns_query_get_rcode(DnsQuery *q) {
+        assert(q);
 
-                } else if (state == DNS_QUERY_SKIPPED && t->state != DNS_QUERY_SKIPPED)
-                        state = t->state;
-        }
+        if (IN_SET(q->state, DNS_QUERY_NULL, DNS_QUERY_PENDING))
+                return -EBUSY;
 
-        if (state == DNS_QUERY_FAILURE)
-                q->rcode = rcode;
+        if (!q->received)
+                return -ESRCH;
+
+        return DNS_PACKET_RCODE(q->received);
+}
+
+int dns_query_get_ifindex(DnsQuery *q) {
+        assert(q);
+
+        if (IN_SET(q->state, DNS_QUERY_NULL, DNS_QUERY_PENDING))
+                return -EBUSY;
+
+        if (!q->received)
+                return -ESRCH;
 
-        dns_query_set_state(q, state);
+        return q->received->ifindex;
 }