lib/addns: Make sure ads_dns_lookup_ns() returns addresses

Windows tends to return A/AAAA records when looking up nameserver
records, Samba seems not to do that. We want to avoid unnecessary
lookups.

Do it differently from ads_dns_lookup_srv: For SRV records we have an
additional layer on top of ads_dns_lookup_srv_send/recv in
dnsquery_srv.c. I don't think that additional layer is necessary, so
converting the SRV lookup to this scheme is a TODO now.

Signed-off-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Stefan Metzmacher <metze@samba.org>

diff --git a/lib/addns/dnsquery.c b/lib/addns/dnsquery.c
index 77178d39f611030e2d5ed2bfec630ee94ae01c47..d450e2654243644f6bbc9faf75d80d2aaefb825e 100644 (file)
--- a/lib/addns/dnsquery.c
+++ b/lib/addns/dnsquery.c
@@ -266,12 +266,15 @@ static bool ads_dns_add_ns_ip(struct dns_rr_ns *nss,
 }
 
 struct ads_dns_lookup_ns_state {
+       struct tevent_context *ev;
        uint32_t timeout;
        struct dns_rr_ns *nss;
        size_t num_nss;
+       size_t num_pending;
 };
 
 static void ads_dns_lookup_ns_done(struct tevent_req *subreq);
+static void ads_dns_lookup_ns_in_done(struct tevent_req *subreq);
 
 struct tevent_req *ads_dns_lookup_ns_send(TALLOC_CTX *mem_ctx,
                                          struct tevent_context *ev,
@@ -286,6 +289,7 @@ struct tevent_req *ads_dns_lookup_ns_send(TALLOC_CTX *mem_ctx,
        if (req == NULL) {
                return NULL;
        }
+       state->ev = ev;
        state->timeout = timeout;
 
        subreq = dns_lookup_send(state, ev, NULL, name, DNS_QCLASS_IN,
@@ -306,6 +310,7 @@ static void ads_dns_lookup_ns_done(struct tevent_req *subreq)
        int ret;
        struct dns_name_packet *reply;
        uint16_t i, idx;
+       struct timeval endtime;
 
        ret = dns_lookup_recv(subreq, state, &reply);
        TALLOC_FREE(subreq);
@@ -361,7 +366,94 @@ static void ads_dns_lookup_ns_done(struct tevent_req *subreq)
                }
        }
 
-       tevent_req_done(req);
+       if (state->timeout == 0) {
+               /*
+                * Queries for IPs don't have time, don't schedule
+                * them.
+                */
+               tevent_req_done(req);
+               return;
+       }
+       endtime = tevent_timeval_current_ofs(state->timeout, 0);
+
+       /*
+        * Launch address queries for any NS records that don't have
+        * IP addresses from the additional section
+        */
+       for (i = 0; i < state->num_nss; i++) {
+               struct dns_rr_ns *ns = &state->nss[i];
+               size_t num_ips = talloc_array_length(ns->ss_s);
+               bool ok;
+
+               if (num_ips > 0) {
+                       /* Already have IPs from additional records */
+                       continue;
+               }
+
+               subreq = ads_dns_lookup_in_send(state,
+                                               state->ev,
+                                               ns->hostname);
+               if (tevent_req_nomem(subreq, req)) {
+                       return;
+               }
+               tevent_req_set_callback(subreq,
+                                       ads_dns_lookup_ns_in_done,
+                                       req);
+
+               ok = tevent_req_set_endtime(subreq, state->ev, endtime);
+               if (!ok) {
+                       tevent_req_oom(req);
+                       return;
+               }
+
+               state->num_pending += 1;
+       }
+
+       if (state->num_pending == 0) {
+               /* All NS records already have IPs, we're done */
+               tevent_req_done(req);
+               return;
+       }
+}
+
+static void ads_dns_lookup_ns_in_done(struct tevent_req *subreq)
+{
+       struct tevent_req *req = tevent_req_callback_data(subreq,
+                                                         struct tevent_req);
+       struct ads_dns_lookup_ns_state *state = tevent_req_data(
+               req, struct ads_dns_lookup_ns_state);
+       size_t num_addrs = 0;
+       char **hostnames = NULL;
+       struct samba_sockaddr *addrs = NULL;
+       NTSTATUS status;
+
+       status = ads_dns_lookup_in_recv(subreq, state, &hostnames, &addrs);
+       TALLOC_FREE(subreq);
+
+       state->num_pending -= 1;
+
+       num_addrs = talloc_array_length(addrs);
+
+       if (NT_STATUS_IS_OK(status) && num_addrs > 0) {
+               size_t j;
+               bool ok;
+
+               /* Add all A records for this hostname */
+               for (j = 0; j < num_addrs; j++) {
+                       ok = ads_dns_add_ns_ip(state->nss,
+                                              state->num_nss,
+                                              hostnames[0],
+                                              &addrs[j]);
+                       if (!ok) {
+                               tevent_req_oom(req);
+                               return;
+                       }
+               }
+       }
+
+       if (state->num_pending == 0) {
+               tevent_req_done(req);
+       }
 }
 
 NTSTATUS ads_dns_lookup_ns_recv(struct tevent_req *req,