Merge pull request #2007 from poettering/resolve-srv

resolved: add support for resolving plain SRV and DNS-SD services

1 files changed, 652 insertions, 188 deletions

diff --git a/src/resolve/resolved-bus.c b/src/resolve/resolved-bus.c
index f0a3b607d4..1908cae2b7 100644
--- a/src/resolve/resolved-bus.c
+++ b/src/resolve/resolved-bus.c
@@ -31,15 +31,14 @@ static int reply_query_state(DnsQuery *q) {
         const char *name;
         int r;
 
-        if (q->request_hostname)
-                name = q->request_hostname;
-        else {
+        if (q->request_address_valid) {
                 r = in_addr_to_string(q->request_family, &q->request_address, &ip);
                 if (r < 0)
                         return r;
 
                 name = ip;
-        }
+        } else
+                name = dns_question_name(q->question);
 
         switch (q->state) {
 
@@ -132,10 +131,9 @@ static int append_address(sd_bus_message *reply, DnsResourceRecord *rr, int ifin
 }
 
 static void bus_method_resolve_hostname_complete(DnsQuery *q) {
-        _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *cname = NULL, *canonical = NULL;
+        _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *canonical = NULL;
         _cleanup_bus_message_unref_ sd_bus_message *reply = NULL;
-        _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
-        unsigned added = 0, i;
+        unsigned added = 0;
         int r;
 
         assert(q);
@@ -145,6 +143,16 @@ static void bus_method_resolve_hostname_complete(DnsQuery *q) {
                 goto finish;
         }
 
+        r = dns_query_process_cname(q);
+        if (r == -ELOOP) {
+                r = sd_bus_reply_method_errorf(q->request, BUS_ERROR_CNAME_LOOP, "CNAME loop detected, or CNAME resolving disabled on '%s'", dns_question_name(q->question));
+                goto finish;
+        }
+        if (r < 0)
+                goto finish;
+        if (r > 0) /* This was a cname, and the query was restarted. */
+                return;
+
         r = sd_bus_message_new_method_return(q->request, &reply);
         if (r < 0)
                 goto finish;
@@ -154,92 +162,42 @@ static void bus_method_resolve_hostname_complete(DnsQuery *q) {
                 goto finish;
 
         if (q->answer) {
-                answer = dns_answer_ref(q->answer);
+                DnsResourceRecord *rr;
+                int ifindex;
 
-                for (i = 0; i < answer->n_rrs; i++) {
-                        r = dns_question_matches_rr(q->question, answer->items[i].rr);
+                DNS_ANSWER_FOREACH_IFINDEX(rr, ifindex, q->answer) {
+                        r = dns_question_matches_rr(q->question, rr);
                         if (r < 0)
                                 goto finish;
-                        if (r == 0) {
-                                /* Hmm, if this is not an address record,
-                                   maybe it's a cname? If so, remember this */
-                                r = dns_question_matches_cname(q->question, answer->items[i].rr);
-                                if (r < 0)
-                                        goto finish;
-                                if (r > 0)
-                                        cname = dns_resource_record_ref(answer->items[i].rr);
-
+                        if (r == 0)
                                 continue;
-                        }
 
-                        r = append_address(reply, answer->items[i].rr, answer->items[i].ifindex);
+                        r = append_address(reply, rr, ifindex);
                         if (r < 0)
                                 goto finish;
 
                         if (!canonical)
-                                canonical = dns_resource_record_ref(answer->items[i].rr);
+                                canonical = dns_resource_record_ref(rr);
 
                         added ++;
                 }
         }
 
-        if (added == 0) {
-                if (!cname) {
-                        r = sd_bus_reply_method_errorf(q->request, BUS_ERROR_NO_SUCH_RR, "'%s' does not have any RR of requested type", q->request_hostname);
-                        goto finish;
-                }
-
-                /* This has a cname? Then update the query with the
-                 * new cname. */
-                r = dns_query_cname_redirect(q, cname);
-                if (r < 0) {
-                        if (r == -ELOOP)
-                                r = sd_bus_reply_method_errorf(q->request, BUS_ERROR_CNAME_LOOP, "CNAME loop on '%s'", q->request_hostname);
-                        else
-                                r = sd_bus_reply_method_errno(q->request, -r, NULL);
-
-                        goto finish;
-                }
-
-                /* Before we restart the query, let's see if any of
-                 * the RRs we already got already answers our query */
-                for (i = 0; i < answer->n_rrs; i++) {
-                        r = dns_question_matches_rr(q->question, answer->items[i].rr);
-                        if (r < 0)
-                                goto finish;
-                        if (r == 0)
-                                continue;
-
-                        r = append_address(reply, answer->items[i].rr, answer->items[i].ifindex);
-                        if (r < 0)
-                                goto finish;
-
-                        if (!canonical)
-                                canonical = dns_resource_record_ref(answer->items[i].rr);
-
-                        added++;
-                }
-
-                /* If we didn't find anything, then let's restart the
-                 * query, this time with the cname */
-                if (added <= 0) {
-                        r = dns_query_go(q);
-                        if (r < 0) {
-                                r = sd_bus_reply_method_errno(q->request, -r, NULL);
-                                goto finish;
-                        }
-
-                        return;
-                }
+        if (added <= 0) {
+                r = sd_bus_reply_method_errorf(q->request, BUS_ERROR_NO_SUCH_RR, "'%s' does not have any RR of the requested type", dns_question_name(q->question));
+                goto finish;
         }
 
         r = sd_bus_message_close_container(reply);
         if (r < 0)
                 goto finish;
 
-        /* Return the precise spelling and uppercasing reported by the server */
+        /* Return the precise spelling and uppercasing and CNAME target reported by the server */
         assert(canonical);
-        r = sd_bus_message_append(reply, "st", DNS_RESOURCE_KEY_NAME(canonical->key), SD_RESOLVED_FLAGS_MAKE(q->answer_protocol, q->answer_family));
+        r = sd_bus_message_append(
+                        reply, "st",
+                        DNS_RESOURCE_KEY_NAME(canonical->key),
+                        SD_RESOLVED_FLAGS_MAKE(q->answer_protocol, q->answer_family));
         if (r < 0)
                 goto finish;
 
@@ -248,23 +206,23 @@ static void bus_method_resolve_hostname_complete(DnsQuery *q) {
 finish:
         if (r < 0) {
                 log_error_errno(r, "Failed to send hostname reply: %m");
-                sd_bus_reply_method_errno(q->request, -r, NULL);
+                sd_bus_reply_method_errno(q->request, r, NULL);
         }
 
         dns_query_free(q);
 }
 
-static int check_ifindex_flags(int ifindex, uint64_t *flags, sd_bus_error *error) {
+static int check_ifindex_flags(int ifindex, uint64_t *flags, uint64_t ok, sd_bus_error *error) {
         assert(flags);
 
         if (ifindex < 0)
                 return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Invalid interface index");
 
-        if (*flags & ~SD_RESOLVED_FLAGS_ALL)
+        if (*flags & ~(SD_RESOLVED_PROTOCOLS_ALL|SD_RESOLVED_NO_CNAME|ok))
                 return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Invalid flags parameter");
 
-        if (*flags == 0)
-                *flags = SD_RESOLVED_FLAGS_DEFAULT;
+        if ((*flags & SD_RESOLVED_PROTOCOLS_ALL) == 0) /* If no protocol is enabled, enable all */
+                *flags |= SD_RESOLVED_PROTOCOLS_ALL;
 
         return 0;
 }
@@ -281,6 +239,8 @@ static int bus_method_resolve_hostname(sd_bus_message *message, void *userdata,
         assert(message);
         assert(m);
 
+        assert_cc(sizeof(int) == sizeof(int32_t));
+
         r = sd_bus_message_read(message, "isit", &ifindex, &hostname, &family, &flags);
         if (r < 0)
                 return r;
@@ -288,41 +248,19 @@ static int bus_method_resolve_hostname(sd_bus_message *message, void *userdata,
         if (!IN_SET(family, AF_INET, AF_INET6, AF_UNSPEC))
                 return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Unknown address family %i", family);
 
-        r = dns_name_normalize(hostname, NULL);
+        r = dns_name_is_valid(hostname);
         if (r < 0)
+                return r;
+        if (r == 0)
                 return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Invalid hostname '%s'", hostname);
 
-        r = check_ifindex_flags(ifindex, &flags, error);
+        r = check_ifindex_flags(ifindex, &flags, 0, error);
         if (r < 0)
                 return r;
 
-        question = dns_question_new(family == AF_UNSPEC ? 2 : 1);
-        if (!question)
-                return -ENOMEM;
-
-        if (family != AF_INET6) {
-                _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
-
-                key = dns_resource_key_new(DNS_CLASS_IN, DNS_TYPE_A, hostname);
-                if (!key)
-                        return -ENOMEM;
-
-                r = dns_question_add(question, key);
-                if (r < 0)
-                        return r;
-        }
-
-        if (family != AF_INET) {
-                _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
-
-                key = dns_resource_key_new(DNS_CLASS_IN, DNS_TYPE_AAAA, hostname);
-                if (!key)
-                        return -ENOMEM;
-
-                r = dns_question_add(question, key);
-                if (r < 0)
-                        return r;
-        }
+        r = dns_question_new_address(&question, family, hostname);
+        if (r < 0)
+                return r;
 
         r = dns_query_new(m, &q, question, ifindex, flags);
         if (r < 0)
@@ -330,27 +268,28 @@ static int bus_method_resolve_hostname(sd_bus_message *message, void *userdata,
 
         q->request = sd_bus_message_ref(message);
         q->request_family = family;
-        q->request_hostname = hostname;
         q->complete = bus_method_resolve_hostname_complete;
 
         r = dns_query_bus_track(q, message);
         if (r < 0)
-                return r;
+                goto fail;
 
         r = dns_query_go(q);
-        if (r < 0) {
-                dns_query_free(q);
-                return r;
-        }
+        if (r < 0)
+                goto fail;
 
         return 1;
+
+fail:
+        dns_query_free(q);
+        return r;
 }
 
 static void bus_method_resolve_address_complete(DnsQuery *q) {
         _cleanup_bus_message_unref_ sd_bus_message *reply = NULL;
-        _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
-        unsigned added = 0, i;
-        int r;
+        DnsResourceRecord *rr;
+        unsigned added = 0;
+        int ifindex, r;
 
         assert(q);
 
@@ -359,6 +298,8 @@ static void bus_method_resolve_address_complete(DnsQuery *q) {
                 goto finish;
         }
 
+        /* We don't process CNAME for PTR lookups. */
+
         r = sd_bus_message_new_method_return(q->request, &reply);
         if (r < 0)
                 goto finish;
@@ -368,16 +309,14 @@ static void bus_method_resolve_address_complete(DnsQuery *q) {
                 goto finish;
 
         if (q->answer) {
-                answer = dns_answer_ref(q->answer);
-
-                for (i = 0; i < answer->n_rrs; i++) {
-                        r = dns_question_matches_rr(q->question, answer->items[i].rr);
+                DNS_ANSWER_FOREACH_IFINDEX(rr, ifindex, q->answer) {
+                        r = dns_question_matches_rr(q->question, rr);
                         if (r < 0)
                                 goto finish;
                         if (r == 0)
                                 continue;
 
-                        r = sd_bus_message_append(reply, "(is)", answer->items[i].ifindex, answer->items[i].rr->ptr.name);
+                        r = sd_bus_message_append(reply, "(is)", ifindex, rr->ptr.name);
                         if (r < 0)
                                 goto finish;
 
@@ -385,12 +324,11 @@ static void bus_method_resolve_address_complete(DnsQuery *q) {
                 }
         }
 
-        if (added == 0) {
+        if (added <= 0) {
                 _cleanup_free_ char *ip = NULL;
 
                 in_addr_to_string(q->request_family, &q->request_address, &ip);
-
-                r = sd_bus_reply_method_errorf(q->request, BUS_ERROR_NO_SUCH_RR, "Address '%s' does not have any RR of requested type", ip);
+                r = sd_bus_reply_method_errorf(q->request, BUS_ERROR_NO_SUCH_RR, "Address '%s' does not have any RR of requested type", strna(ip));
                 goto finish;
         }
 
@@ -407,16 +345,14 @@ static void bus_method_resolve_address_complete(DnsQuery *q) {
 finish:
         if (r < 0) {
                 log_error_errno(r, "Failed to send address reply: %m");
-                sd_bus_reply_method_errno(q->request, -r, NULL);
+                sd_bus_reply_method_errno(q->request, r, NULL);
         }
 
         dns_query_free(q);
 }
 
 static int bus_method_resolve_address(sd_bus_message *message, void *userdata, sd_bus_error *error) {
-        _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
         _cleanup_(dns_question_unrefp) DnsQuestion *question = NULL;
-        _cleanup_free_ char *reverse = NULL;
         Manager *m = userdata;
         int family, ifindex;
         uint64_t flags;
@@ -428,6 +364,8 @@ static int bus_method_resolve_address(sd_bus_message *message, void *userdata, s
         assert(message);
         assert(m);
 
+        assert_cc(sizeof(int) == sizeof(int32_t));
+
         r = sd_bus_message_read(message, "ii", &ifindex, &family);
         if (r < 0)
                 return r;
@@ -446,25 +384,11 @@ static int bus_method_resolve_address(sd_bus_message *message, void *userdata, s
         if (r < 0)
                 return r;
 
-        r = check_ifindex_flags(ifindex, &flags, error);
-        if (r < 0)
-                return r;
-
-        r = dns_name_reverse(family, d, &reverse);
+        r = check_ifindex_flags(ifindex, &flags, 0, error);
         if (r < 0)
                 return r;
 
-        question = dns_question_new(1);
-        if (!question)
-                return -ENOMEM;
-
-        key = dns_resource_key_new_consume(DNS_CLASS_IN, DNS_TYPE_PTR, reverse);
-        if (!key)
-                return -ENOMEM;
-
-        reverse = NULL;
-
-        r = dns_question_add(question, key);
+        r = dns_question_new_reverse(&question, family, d);
         if (r < 0)
                 return r;
 
@@ -479,21 +403,58 @@ static int bus_method_resolve_address(sd_bus_message *message, void *userdata, s
 
         r = dns_query_bus_track(q, message);
         if (r < 0)
-                return r;
+                goto fail;
 
         r = dns_query_go(q);
-        if (r < 0) {
-                dns_query_free(q);
-                return r;
-        }
+        if (r < 0)
+                goto fail;
 
         return 1;
+
+fail:
+        dns_query_free(q);
+        return r;
+}
+
+static int bus_message_append_rr(sd_bus_message *m, DnsResourceRecord *rr, int ifindex) {
+        _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
+        size_t start;
+        int r;
+
+        assert(m);
+        assert(rr);
+
+        r = sd_bus_message_open_container(m, 'r', "iqqay");
+        if (r < 0)
+                return r;
+
+        r = sd_bus_message_append(m, "iqq",
+                                  ifindex,
+                                  rr->key->class,
+                                  rr->key->type);
+        if (r < 0)
+                return r;
+
+        r = dns_packet_new(&p, DNS_PROTOCOL_DNS, 0);
+        if (r < 0)
+                return r;
+
+        p->refuse_compression = true;
+
+        r = dns_packet_append_rr(p, rr, &start);
+        if (r < 0)
+                return r;
+
+        r = sd_bus_message_append_array(m, 'y', DNS_PACKET_DATA(p) + start, p->size - start);
+        if (r < 0)
+                return r;
+
+        return sd_bus_message_close_container(m);
 }
 
 static void bus_method_resolve_record_complete(DnsQuery *q) {
         _cleanup_bus_message_unref_ sd_bus_message *reply = NULL;
-        _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL;
-        unsigned added = 0, i;
+        unsigned added = 0;
         int r;
 
         assert(q);
@@ -503,6 +464,16 @@ static void bus_method_resolve_record_complete(DnsQuery *q) {
                 goto finish;
         }
 
+        r = dns_query_process_cname(q);
+        if (r == -ELOOP) {
+                r = sd_bus_reply_method_errorf(q->request, BUS_ERROR_CNAME_LOOP, "CNAME loop detected, or CNAME resolving disabled on '%s'", dns_question_name(q->question));
+                goto finish;
+        }
+        if (r < 0)
+                goto finish;
+        if (r > 0) /* Following a CNAME */
+                return;
+
         r = sd_bus_message_new_method_return(q->request, &reply);
         if (r < 0)
                 goto finish;
@@ -512,44 +483,17 @@ static void bus_method_resolve_record_complete(DnsQuery *q) {
                 goto finish;
 
         if (q->answer) {
-                answer = dns_answer_ref(q->answer);
-
-                for (i = 0; i < answer->n_rrs; i++) {
-                        _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
-                        size_t start;
+                DnsResourceRecord *rr;
+                int ifindex;
 
-                        r = dns_question_matches_rr(q->question, answer->items[i].rr);
+                DNS_ANSWER_FOREACH_IFINDEX(rr, ifindex, q->answer) {
+                        r = dns_question_matches_rr(q->question, rr);
                         if (r < 0)
                                 goto finish;
                         if (r == 0)
                                 continue;
 
-                        r = dns_packet_new(&p, DNS_PROTOCOL_DNS, 0);
-                        if (r < 0)
-                                goto finish;
-
-                        p->refuse_compression = true;
-
-                        r = dns_packet_append_rr(p, answer->items[i].rr, &start);
-                        if (r < 0)
-                                goto finish;
-
-                        r = sd_bus_message_open_container(reply, 'r', "iqqay");
-                        if (r < 0)
-                                goto finish;
-
-                        r = sd_bus_message_append(reply, "iqq",
-                                                  answer->items[i].ifindex,
-                                                  answer->items[i].rr->key->class,
-                                                  answer->items[i].rr->key->type);
-                        if (r < 0)
-                                goto finish;
-
-                        r = sd_bus_message_append_array(reply, 'y', DNS_PACKET_DATA(p) + start, p->size - start);
-                        if (r < 0)
-                                goto finish;
-
-                        r = sd_bus_message_close_container(reply);
+                        r = bus_message_append_rr(reply, rr, ifindex);
                         if (r < 0)
                                 goto finish;
 
@@ -558,7 +502,7 @@ static void bus_method_resolve_record_complete(DnsQuery *q) {
         }
 
         if (added <= 0) {
-                r = sd_bus_reply_method_errorf(q->request, BUS_ERROR_NO_SUCH_RR, "Name '%s' does not have any RR of the requested type", q->request_hostname);
+                r = sd_bus_reply_method_errorf(q->request, BUS_ERROR_NO_SUCH_RR, "Name '%s' does not have any RR of the requested type", dns_question_name(q->question));
                 goto finish;
         }
 
@@ -575,7 +519,7 @@ static void bus_method_resolve_record_complete(DnsQuery *q) {
 finish:
         if (r < 0) {
                 log_error_errno(r, "Failed to send record reply: %m");
-                sd_bus_reply_method_errno(q->request, -r, NULL);
+                sd_bus_reply_method_errno(q->request, r, NULL);
         }
 
         dns_query_free(q);
@@ -594,15 +538,19 @@ static int bus_method_resolve_record(sd_bus_message *message, void *userdata, sd
         assert(message);
         assert(m);
 
+        assert_cc(sizeof(int) == sizeof(int32_t));
+
         r = sd_bus_message_read(message, "isqqt", &ifindex, &name, &class, &type, &flags);
         if (r < 0)
                 return r;
 
-        r = dns_name_normalize(name, NULL);
+        r = dns_name_is_valid(name);
         if (r < 0)
+                return r;
+        if (r == 0)
                 return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Invalid name '%s'", name);
 
-        r = check_ifindex_flags(ifindex, &flags, error);
+        r = check_ifindex_flags(ifindex, &flags, 0, error);
         if (r < 0)
                 return r;
 
@@ -623,20 +571,535 @@ static int bus_method_resolve_record(sd_bus_message *message, void *userdata, sd
                 return r;
 
         q->request = sd_bus_message_ref(message);
-        q->request_hostname = name;
         q->complete = bus_method_resolve_record_complete;
 
         r = dns_query_bus_track(q, message);
         if (r < 0)
-                return r;
+                goto fail;
 
         r = dns_query_go(q);
+        if (r < 0)
+                goto fail;
+
+        return 1;
+
+fail:
+        dns_query_free(q);
+        return r;
+}
+
+static int append_srv(DnsQuery *q, sd_bus_message *reply, DnsResourceRecord *rr) {
+        _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *canonical = NULL;
+        DnsQuery *aux;
+        int r;
+
+        assert(q);
+        assert(reply);
+        assert(rr);
+        assert(rr->key);
+
+        if (rr->key->type != DNS_TYPE_SRV)
+                return 0;
+
+        if ((q->flags & SD_RESOLVED_NO_ADDRESS) == 0) {
+                /* First, let's see if we could find an appropriate A or AAAA
+                 * record for the SRV record */
+                LIST_FOREACH(auxiliary_queries, aux, q->auxiliary_queries) {
+                        DnsResourceRecord *zz;
+
+                        if (aux->state != DNS_TRANSACTION_SUCCESS)
+                                continue;
+                        if (aux->auxiliary_result != 0)
+                                continue;
+
+                        r = dns_name_equal(dns_question_name(aux->question), rr->srv.name);
+                        if (r < 0)
+                                return r;
+                        if (r == 0)
+                                continue;
+
+                        DNS_ANSWER_FOREACH(zz, aux->answer) {
+
+                                r = dns_question_matches_rr(aux->question, zz);
+                                if (r < 0)
+                                        return r;
+                                if (r == 0)
+                                        continue;
+
+                                canonical = dns_resource_record_ref(zz);
+                                break;
+                        }
+
+                        if (canonical)
+                                break;
+                }
+
+                /* Is there are successful A/AAAA lookup for this SRV RR? If not, don't add it */
+                if (!canonical)
+                        return 0;
+        }
+
+        r = sd_bus_message_open_container(reply, 'r', "qqqsa(iiay)s");
+        if (r < 0)
+                return r;
+
+        r = sd_bus_message_append(
+                        reply,
+                        "qqqs",
+                        rr->srv.priority, rr->srv.weight, rr->srv.port, rr->srv.name);
+        if (r < 0)
+                return r;
+
+        r = sd_bus_message_open_container(reply, 'a', "(iiay)");
+        if (r < 0)
+                return r;
+
+        if ((q->flags & SD_RESOLVED_NO_ADDRESS) == 0) {
+                LIST_FOREACH(auxiliary_queries, aux, q->auxiliary_queries) {
+                        DnsResourceRecord *zz;
+                        int ifindex;
+
+                        if (aux->state != DNS_TRANSACTION_SUCCESS)
+                                continue;
+                        if (aux->auxiliary_result != 0)
+                                continue;
+
+                        r = dns_name_equal(dns_question_name(aux->question), rr->srv.name);
+                        if (r < 0)
+                                return r;
+                        if (r == 0)
+                                continue;
+
+                        DNS_ANSWER_FOREACH_IFINDEX(zz, ifindex, aux->answer) {
+
+                                r = dns_question_matches_rr(aux->question, zz);
+                                if (r < 0)
+                                        return r;
+                                if (r == 0)
+                                        continue;
+
+                                r = append_address(reply, zz, ifindex);
+                                if (r < 0)
+                                        return r;
+                        }
+                }
+        }
+
+        r = sd_bus_message_close_container(reply);
+        if (r < 0)
+                return r;
+
+        /* Note that above we appended the hostname as encoded in the
+         * SRV, and here the canonical hostname this maps to. */
+        r = sd_bus_message_append(reply, "s", canonical ? DNS_RESOURCE_KEY_NAME(canonical->key) : rr->srv.name);
+        if (r < 0)
+                return r;
+
+        r = sd_bus_message_close_container(reply);
+        if (r < 0)
+                return r;
+
+        return 1;
+}
+
+static int append_txt(sd_bus_message *reply, DnsResourceRecord *rr) {
+        DnsTxtItem *i;
+        int r;
+
+        assert(reply);
+        assert(rr);
+        assert(rr->key);
+
+        if (rr->key->type != DNS_TYPE_TXT)
+                return 0;
+
+        LIST_FOREACH(items, i, rr->txt.items) {
+
+                if (i->length <= 0)
+                        continue;
+
+                r = sd_bus_message_append_array(reply, 'y', i->data, i->length);
+                if (r < 0)
+                        return r;
+        }
+
+        return 1;
+}
+
+static void resolve_service_all_complete(DnsQuery *q) {
+        _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *canonical = NULL;
+        _cleanup_(sd_bus_message_unrefp) sd_bus_message *reply = NULL;
+        _cleanup_free_ char *name = NULL, *type = NULL, *domain = NULL;
+        DnsQuery *aux;
+        unsigned added = false;
+        int r;
+
+        assert(q);
+
+        if (q->block_all_complete > 0)
+                return;
+
+        if ((q->flags & SD_RESOLVED_NO_ADDRESS) == 0) {
+                DnsQuery *bad = NULL;
+                bool have_success = false;
+
+                LIST_FOREACH(auxiliary_queries, aux, q->auxiliary_queries) {
+
+                        switch (aux->state) {
+
+                        case DNS_TRANSACTION_PENDING:
+                                /* If an auxiliary query is still pending, let's wait */
+                                return;
+
+                        case DNS_TRANSACTION_SUCCESS:
+                                if (aux->auxiliary_result == 0)
+                                        have_success = true;
+                                else
+                                        bad = aux;
+                                break;
+
+                        default:
+                                bad = aux;
+                                break;
+                        }
+                }
+
+                if (!have_success) {
+                        /* We can only return one error, hence pick the last error we encountered */
+
+                        assert(bad);
+
+                        if (bad->state == DNS_TRANSACTION_SUCCESS) {
+                                assert(bad->auxiliary_result != 0);
+
+                                if (bad->auxiliary_result == -ELOOP) {
+                                        r = sd_bus_reply_method_errorf(q->request, BUS_ERROR_CNAME_LOOP, "CNAME loop detected, or CNAME resolving disabled on '%s'", dns_question_name(bad->question));
+                                        goto finish;
+                                }
+
+                                r = bad->auxiliary_result;
+                                goto finish;
+                        }
+
+                        r = reply_query_state(bad);
+                        goto finish;
+                }
+        }
+
+        r = sd_bus_message_new_method_return(q->request, &reply);
+        if (r < 0)
+                goto finish;
+
+        r = sd_bus_message_open_container(reply, 'a', "(qqqsa(iiay)s)");
+        if (r < 0)
+                goto finish;
+
+        if (q->answer) {
+                DnsResourceRecord *rr;
+
+                DNS_ANSWER_FOREACH(rr, q->answer) {
+                        r = dns_question_matches_rr(q->question, rr);
+                        if (r < 0)
+                                goto finish;
+                        if (r == 0)
+                                continue;
+
+                        r = append_srv(q, reply, rr);
+                        if (r < 0)
+                                goto finish;
+                        if (r == 0) /* not an SRV record */
+                                continue;
+
+                        if (!canonical)
+                                canonical = dns_resource_record_ref(rr);
+
+                        added++;
+                }
+        }
+
+        if (added <= 0) {
+                r = sd_bus_reply_method_errorf(q->request, BUS_ERROR_NO_SUCH_RR, "'%s' does not have any RR of the requested type", dns_question_name(q->question));
+                goto finish;
+        }
+
+        r = sd_bus_message_close_container(reply);
+        if (r < 0)
+                goto finish;
+
+        r = sd_bus_message_open_container(reply, 'a', "ay");
+        if (r < 0)
+                goto finish;
+
+        if (q->answer) {
+                DnsResourceRecord *rr;
+
+                DNS_ANSWER_FOREACH(rr, q->answer) {
+                        r = dns_question_matches_rr(q->question, rr);
+                        if (r < 0)
+                                goto finish;
+                        if (r == 0)
+                                continue;
+
+                        r = append_txt(reply, rr);
+                        if (r < 0)
+                                goto finish;
+                }
+        }
+
+        r = sd_bus_message_close_container(reply);
+        if (r < 0)
+                goto finish;
+
+        assert(canonical);
+        r = dns_service_split(DNS_RESOURCE_KEY_NAME(canonical->key), &name, &type, &domain);
+        if (r < 0)
+                goto finish;
+
+        r = sd_bus_message_append(
+                        reply,
+                        "ssst",
+                        name, type, domain,
+                        SD_RESOLVED_FLAGS_MAKE(q->answer_protocol, q->answer_family));
+        if (r < 0)
+                goto finish;
+
+        r = sd_bus_send(q->manager->bus, reply, NULL);
+
+finish:
+        if (r < 0) {
+                log_error_errno(r, "Failed to send service reply: %m");
+                sd_bus_reply_method_errno(q->request, r, NULL);
+        }
+
+        dns_query_free(q);
+}
+
+static void resolve_service_hostname_complete(DnsQuery *q) {
+        int r;
+
+        assert(q);
+        assert(q->auxiliary_for);
+
+        if (q->state != DNS_TRANSACTION_SUCCESS) {
+                resolve_service_all_complete(q->auxiliary_for);
+                return;
+        }
+
+        r = dns_query_process_cname(q);
+        if (r > 0) /* This was a cname, and the query was restarted. */
+                return;
+
+        /* This auxiliary lookup is finished or failed, let's see if all are finished now. */
+        q->auxiliary_result = r;
+        resolve_service_all_complete(q->auxiliary_for);
+}
+
+static int resolve_service_hostname(DnsQuery *q, DnsResourceRecord *rr, int ifindex) {
+        _cleanup_(dns_question_unrefp) DnsQuestion *question = NULL;
+        DnsQuery *aux;
+        int r;
+
+        assert(q);
+        assert(rr);
+        assert(rr->key);
+        assert(rr->key->type == DNS_TYPE_SRV);
+
+        /* OK, we found an SRV record for the service. Let's resolve
+         * the hostname included in it */
+
+        r = dns_question_new_address(&question, q->request_family, rr->srv.name);
+        if (r < 0)
+                return r;
+
+        r = dns_query_new(q->manager, &aux, question, ifindex, q->flags);
+        if (r < 0)
+                return r;
+
+        aux->request_family = q->request_family;
+        aux->complete = resolve_service_hostname_complete;
+
+        r = dns_query_make_auxiliary(aux, q);
+        if (r == -EAGAIN) {
+                /* Too many auxiliary lookups? If so, don't complain,
+                 * let's just not add this one, we already have more
+                 * than enough */
+
+                dns_query_free(aux);
+                return 0;
+        }
+        if (r < 0)
+                goto fail;
+
+        /* Note that auxiliary queries do not track the original bus
+         * client, only the primary request does that. */
+
+        r = dns_query_go(aux);
+        if (r < 0)
+                goto fail;
+
+        return 1;
+
+fail:
+        dns_query_free(aux);
+        return r;
+}
+
+static void bus_method_resolve_service_complete(DnsQuery *q) {
+        unsigned found = 0;
+        int r;
+
+        assert(q);
+
+        if (q->state != DNS_TRANSACTION_SUCCESS) {
+                r = reply_query_state(q);
+                goto finish;
+        }
+
+        r = dns_query_process_cname(q);
+        if (r == -ELOOP) {
+                r = sd_bus_reply_method_errorf(q->request, BUS_ERROR_CNAME_LOOP, "CNAME loop detected, or CNAME resolving disabled on '%s'", dns_question_name(q->question));
+                goto finish;
+        }
+        if (r < 0)
+                goto finish;
+        if (r > 0) /* This was a cname, and the query was restarted. */
+                return;
+
+        if (q->answer) {
+                DnsResourceRecord *rr;
+                int ifindex;
+
+                DNS_ANSWER_FOREACH_IFINDEX(rr, ifindex, q->answer) {
+                        r = dns_question_matches_rr(q->question, rr);
+                        if (r < 0)
+                                goto finish;
+                        if (r == 0)
+                                continue;
+
+                        if (rr->key->type != DNS_TYPE_SRV)
+                                continue;
+
+                        if ((q->flags & SD_RESOLVED_NO_ADDRESS) == 0) {
+                                q->block_all_complete ++;
+                                r = resolve_service_hostname(q, rr, ifindex);
+                                q->block_all_complete --;
+
+                                if (r < 0)
+                                        goto finish;
+                        }
+
+                        found++;
+                }
+        }
+
+        if (found <= 0) {
+                r = sd_bus_reply_method_errorf(q->request, BUS_ERROR_NO_SUCH_RR, "'%s' does not have any RR of the requested type", dns_question_name(q->question));
+                goto finish;
+        }
+
+        /* Maybe we are already finished? check now... */
+        resolve_service_all_complete(q);
+        return;
+
+finish:
         if (r < 0) {
-                dns_query_free(q);
+                log_error_errno(r, "Failed to send service reply: %m");
+                sd_bus_reply_method_errno(q->request, r, NULL);
+        }
+
+        dns_query_free(q);
+}
+
+static int bus_method_resolve_service(sd_bus_message *message, void *userdata, sd_bus_error *error) {
+        _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL;
+        _cleanup_(dns_question_unrefp) DnsQuestion *question = NULL;
+        const char *name, *type, *domain, *joined;
+        _cleanup_free_ char *n = NULL;
+        Manager *m = userdata;
+        int family, ifindex;
+        uint64_t flags;
+        DnsQuery *q;
+        int r;
+
+        assert(message);
+        assert(m);
+
+        assert_cc(sizeof(int) == sizeof(int32_t));
+
+        r = sd_bus_message_read(message, "isssit", &ifindex, &name, &type, &domain, &family, &flags);
+        if (r < 0)
                 return r;
+
+        if (!IN_SET(family, AF_INET, AF_INET6, AF_UNSPEC))
+                return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Unknown address family %i", family);
+
+        if (isempty(name))
+                name = NULL;
+        else {
+                if (!dns_service_name_is_valid(name))
+                        return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Invalid service name '%s'", name);
         }
 
+        if (isempty(type))
+                type = NULL;
+        else {
+                r = dns_srv_type_verify(type);
+                if (r < 0)
+                        return r;
+                if (r == 0)
+                        return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Invalid SRV service type '%s'", type);
+        }
+
+        r = dns_name_is_valid(domain);
+        if (r < 0)
+                return r;
+        if (r == 0)
+                return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Invalid domain '%s'", domain);
+
+        if (name && !type)
+                return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Service name cannot be specified without service type.");
+
+        r = check_ifindex_flags(ifindex, &flags, SD_RESOLVED_NO_TXT|SD_RESOLVED_NO_ADDRESS, error);
+        if (r < 0)
+                return r;
+
+        if (type) {
+                /* If the type is specified, we generate the full domain name to look up ourselves */
+                r = dns_service_join(name, type, domain, &n);
+                if (r < 0)
+                        return r;
+
+                joined = n;
+        } else
+                /* If no type is specified, we assume the domain
+                 * contains the full domain name to lookup already */
+                joined = domain;
+
+        r = dns_question_new_service(&question, joined, !(flags & SD_RESOLVED_NO_TXT));
+        if (r < 0)
+                return r;
+
+        r = dns_query_new(m, &q, question, ifindex, flags);
+        if (r < 0)
+                return r;
+
+        q->request = sd_bus_message_ref(message);
+        q->request_family = family;
+        q->complete = bus_method_resolve_service_complete;
+
+        r = dns_query_bus_track(q, message);
+        if (r < 0)
+                goto fail;
+
+        r = dns_query_go(q);
+        if (r < 0)
+                goto fail;
+
         return 1;
+
+fail:
+        dns_query_free(q);
+        return r;
 }
 
 static const sd_bus_vtable resolve_vtable[] = {
@@ -644,6 +1107,7 @@ static const sd_bus_vtable resolve_vtable[] = {
         SD_BUS_METHOD("ResolveHostname", "isit", "a(iiay)st", bus_method_resolve_hostname, SD_BUS_VTABLE_UNPRIVILEGED),
         SD_BUS_METHOD("ResolveAddress", "iiayt", "a(is)t", bus_method_resolve_address, SD_BUS_VTABLE_UNPRIVILEGED),
         SD_BUS_METHOD("ResolveRecord", "isqqt", "a(iqqay)t", bus_method_resolve_record, SD_BUS_VTABLE_UNPRIVILEGED),
+        SD_BUS_METHOD("ResolveService", "isssit", "a(qqqsa(iiay)s)aayssst", bus_method_resolve_service, SD_BUS_VTABLE_UNPRIVILEGED),
         SD_BUS_VTABLE_END,
 };