source4/dns_server/dns_query.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    DNS server handler for queries
   5
   6    Copyright (C) 2010 Kai Blin  <kai@samba.org>
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  20 */
  21
  22 #include "includes.h"
  23 #include "smbd/service_task.h"
  24 #include "libcli/util/werror.h"
  25 #include "librpc/ndr/libndr.h"
  26 #include "librpc/gen_ndr/ndr_dns.h"
  27 #include "librpc/gen_ndr/ndr_dnsp.h"
  28 #include <ldb.h>
  29 #include "param/param.h"
  30 #include "dsdb/samdb/samdb.h"
  31 #include "dsdb/common/util.h"
  32 #include "dns_server/dns_server.h"
  33 #include "libcli/dns/libdns.h"
  34 #include "lib/util/util_net.h"
  35 #include "lib/util/tevent_werror.h"
  36
  37 static WERROR create_response_rr(const struct dns_name_question *question,
  38                                  const struct dnsp_DnssrvRpcRecord *rec,
  39                                  struct dns_res_rec **answers, uint16_t *ancount)
  40 {
  41         struct dns_res_rec *ans = *answers;
  42         uint16_t ai = *ancount;
  43         char *tmp;
  44         uint32_t i;
  45
  46         ZERO_STRUCT(ans[ai]);
  47
  48         switch (rec->wType) {
  49         case DNS_QTYPE_CNAME:
  50                 ans[ai].rdata.cname_record = talloc_strdup(ans, rec->data.cname);
  51                 W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.cname_record);
  52                 break;
  53         case DNS_QTYPE_A:
  54                 ans[ai].rdata.ipv4_record = talloc_strdup(ans, rec->data.ipv4);
  55                 W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.ipv4_record);
  56                 break;
  57         case DNS_QTYPE_AAAA:
  58                 ans[ai].rdata.ipv6_record = talloc_strdup(ans, rec->data.ipv6);
  59                 W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.ipv6_record);
  60                 break;
  61         case DNS_TYPE_NS:
  62                 ans[ai].rdata.ns_record = talloc_strdup(ans, rec->data.ns);
  63                 W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.ns_record);
  64                 break;
  65         case DNS_QTYPE_SRV:
  66                 ans[ai].rdata.srv_record.priority = rec->data.srv.wPriority;
  67                 ans[ai].rdata.srv_record.weight   = rec->data.srv.wWeight;
  68                 ans[ai].rdata.srv_record.port     = rec->data.srv.wPort;
  69                 ans[ai].rdata.srv_record.target   = talloc_strdup(
  70                         ans, rec->data.srv.nameTarget);
  71                 W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.srv_record.target);
  72                 break;
  73         case DNS_QTYPE_SOA:
  74                 ans[ai].rdata.soa_record.mname   = talloc_strdup(
  75                         ans, rec->data.soa.mname);
  76                 W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.soa_record.mname);
  77                 ans[ai].rdata.soa_record.rname   = talloc_strdup(
  78                         ans, rec->data.soa.rname);
  79                 W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.soa_record.rname);
  80                 ans[ai].rdata.soa_record.serial  = rec->data.soa.serial;
  81                 ans[ai].rdata.soa_record.refresh = rec->data.soa.refresh;
  82                 ans[ai].rdata.soa_record.retry   = rec->data.soa.retry;
  83                 ans[ai].rdata.soa_record.expire  = rec->data.soa.expire;
  84                 ans[ai].rdata.soa_record.minimum = rec->data.soa.minimum;
  85                 break;
  86         case DNS_QTYPE_PTR:
  87                 ans[ai].rdata.ptr_record = talloc_strdup(ans, rec->data.ptr);
  88                 break;
  89         case DNS_QTYPE_TXT:
  90                 tmp = talloc_asprintf(ans, "\"%s\"", rec->data.txt.str[0]);
  91                 W_ERROR_HAVE_NO_MEMORY(tmp);
  92                 for (i=1; i<rec->data.txt.count; i++) {
  93                         tmp = talloc_asprintf_append_buffer(
  94                                 tmp, " \"%s\"", rec->data.txt.str[i]);
  95                         W_ERROR_HAVE_NO_MEMORY(tmp);
  96                 }
  97                 ans[ai].rdata.txt_record.txt = tmp;
  98                 break;
  99         default:
 100                 DEBUG(0, ("Got unhandled type %u query.\n", rec->wType));
 101                 return DNS_ERR(NOT_IMPLEMENTED);
 102         }
 103
 104         ans[ai].name = talloc_strdup(ans, question->name);
 105         W_ERROR_HAVE_NO_MEMORY(ans[ai].name);
 106         ans[ai].rr_type = rec->wType;
 107         ans[ai].rr_class = DNS_QCLASS_IN;
 108         ans[ai].ttl = rec->dwTtlSeconds;
 109         ans[ai].length = UINT16_MAX;
 110         ai++;
 111
 112         *answers = ans;
 113         *ancount = ai;
 114
 115         return WERR_OK;
 116 }
 117
 118 struct ask_forwarder_state {
 119         struct tevent_context *ev;
 120         uint16_t id;
 121         struct dns_name_packet in_packet;
 122 };
 123
 124 static void ask_forwarder_done(struct tevent_req *subreq);
 125
 126 static struct tevent_req *ask_forwarder_send(
 127         TALLOC_CTX *mem_ctx, struct tevent_context *ev,
 128         const char *forwarder, struct dns_name_question *question)
 129 {
 130         struct tevent_req *req, *subreq;
 131         struct ask_forwarder_state *state;
 132         struct dns_name_packet out_packet = { 0, };
 133         DATA_BLOB out_blob;
 134         enum ndr_err_code ndr_err;
 135
 136         req = tevent_req_create(mem_ctx, &state, struct ask_forwarder_state);
 137         if (req == NULL) {
 138                 return NULL;
 139         }
 140         state->ev = ev;
 141         generate_random_buffer((uint8_t *)&state->id, sizeof(state->id));
 142
 143         if (!is_ipaddress(forwarder)) {
 144                 DEBUG(0, ("Invalid 'dns forwarder' setting '%s', needs to be "
 145                           "an IP address\n", forwarder));
 146                 tevent_req_werror(req, DNS_ERR(NAME_ERROR));
 147                 return tevent_req_post(req, ev);
 148         }
 149
 150         out_packet.id = state->id;
 151         out_packet.operation |= DNS_OPCODE_QUERY | DNS_FLAG_RECURSION_DESIRED;
 152         out_packet.qdcount = 1;
 153         out_packet.questions = question;
 154
 155         ndr_err = ndr_push_struct_blob(
 156                 &out_blob, state, &out_packet,
 157                 (ndr_push_flags_fn_t)ndr_push_dns_name_packet);
 158         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 159                 tevent_req_werror(req, DNS_ERR(SERVER_FAILURE));
 160                 return tevent_req_post(req, ev);
 161         }
 162         subreq = dns_udp_request_send(state, ev, forwarder, out_blob.data,
 163                                       out_blob.length);
 164         if (tevent_req_nomem(subreq, req)) {
 165                 return tevent_req_post(req, ev);
 166         }
 167         tevent_req_set_callback(subreq, ask_forwarder_done, req);
 168         return req;
 169 }
 170
 171 static void ask_forwarder_done(struct tevent_req *subreq)
 172 {
 173         struct tevent_req *req = tevent_req_callback_data(
 174                 subreq, struct tevent_req);
 175         struct ask_forwarder_state *state = tevent_req_data(
 176                 req, struct ask_forwarder_state);
 177         DATA_BLOB in_blob;
 178         enum ndr_err_code ndr_err;
 179         WERROR ret;
 180
 181         ret = dns_udp_request_recv(subreq, state,
 182                                    &in_blob.data, &in_blob.length);
 183         TALLOC_FREE(subreq);
 184         if (tevent_req_werror(req, ret)) {
 185                 return;
 186         }
 187
 188         ndr_err = ndr_pull_struct_blob(
 189                 &in_blob, state, &state->in_packet,
 190                 (ndr_pull_flags_fn_t)ndr_pull_dns_name_packet);
 191         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 192                 tevent_req_werror(req, DNS_ERR(SERVER_FAILURE));
 193                 return;
 194         }
 195         if (state->in_packet.id != state->id) {
 196                 tevent_req_werror(req, DNS_ERR(NAME_ERROR));
 197                 return;
 198         }
 199         tevent_req_done(req);
 200 }
 201
 202 static WERROR ask_forwarder_recv(
 203         struct tevent_req *req, TALLOC_CTX *mem_ctx,
 204         struct dns_res_rec **answers, uint16_t *ancount,
 205         struct dns_res_rec **nsrecs, uint16_t *nscount,
 206         struct dns_res_rec **additional, uint16_t *arcount)
 207 {
 208         struct ask_forwarder_state *state = tevent_req_data(
 209                 req, struct ask_forwarder_state);
 210         struct dns_name_packet *in_packet = &state->in_packet;
 211         WERROR err;
 212
 213         if (tevent_req_is_werror(req, &err)) {
 214                 return err;
 215         }
 216
 217         *ancount = in_packet->ancount;
 218         *answers = talloc_move(mem_ctx, &in_packet->answers);
 219
 220         *nscount = in_packet->nscount;
 221         *nsrecs = talloc_move(mem_ctx, &in_packet->nsrecs);
 222
 223         *arcount = in_packet->arcount;
 224         *additional = talloc_move(mem_ctx, &in_packet->additional);
 225
 226         return WERR_OK;
 227 }
 228
 229 static WERROR handle_question(struct dns_server *dns,
 230                               TALLOC_CTX *mem_ctx,
 231                               const struct dns_name_question *question,
 232                               struct dns_res_rec **answers, uint16_t *ancount)
 233 {
 234         struct dns_res_rec *ans = *answers;
 235         WERROR werror;
 236         unsigned int ri;
 237         struct dnsp_DnssrvRpcRecord *recs;
 238         uint16_t rec_count, ai = *ancount;
 239         struct ldb_dn *dn = NULL;
 240
 241         werror = dns_name2dn(dns, mem_ctx, question->name, &dn);
 242         W_ERROR_NOT_OK_RETURN(werror);
 243
 244         werror = dns_lookup_records(dns, mem_ctx, dn, &recs, &rec_count);
 245         W_ERROR_NOT_OK_RETURN(werror);
 246
 247         ans = talloc_realloc(mem_ctx, ans, struct dns_res_rec, rec_count + ai);
 248         if (ans == NULL) {
 249                 return WERR_NOMEM;
 250         }
 251
 252         for (ri = 0; ri < rec_count; ri++) {
 253                 if ((recs[ri].wType == DNS_TYPE_CNAME) &&
 254                     ((question->question_type == DNS_QTYPE_A) ||
 255                      (question->question_type == DNS_QTYPE_AAAA))) {
 256                         struct dns_name_question *new_q =
 257                                 talloc(mem_ctx, struct dns_name_question);
 258
 259                         if (new_q == NULL) {
 260                                 return WERR_NOMEM;
 261                         }
 262
 263                         /* We reply with one more record, so grow the array */
 264                         ans = talloc_realloc(mem_ctx, ans, struct dns_res_rec,
 265                                              rec_count + 1);
 266                         if (ans == NULL) {
 267                                 TALLOC_FREE(new_q);
 268                                 return WERR_NOMEM;
 269                         }
 270
 271                         /* First put in the CNAME record */
 272                         werror = create_response_rr(question, &recs[ri], &ans, &ai);
 273                         if (!W_ERROR_IS_OK(werror)) {
 274                                 return werror;
 275                         }
 276
 277                         /* And then look up the name it points at.. */
 278
 279                         /* First build up the new question */
 280                         new_q->question_type = question->question_type;
 281                         new_q->question_class = question->question_class;
 282                         if (new_q->question_type == DNS_QTYPE_A) {
 283                                 new_q->name = talloc_strdup(new_q, recs[ri].data.ipv4);
 284                         } else if (new_q->question_type == DNS_QTYPE_AAAA) {
 285                                 new_q->name = talloc_strdup(new_q, recs[ri].data.ipv6);
 286                         }
 287                         if (new_q->name == NULL) {
 288                                 TALLOC_FREE(new_q);
 289                                 return WERR_NOMEM;
 290                         }
 291                         /* and then call the lookup again */
 292                         werror = handle_question(dns, mem_ctx, new_q, &ans, &ai);
 293                         if (!W_ERROR_IS_OK(werror)) {
 294                                 return werror;
 295                         }
 296
 297
 298                         continue;
 299                 }
 300                 if ((question->question_type != DNS_QTYPE_ALL) &&
 301                     (recs[ri].wType != question->question_type)) {
 302                         continue;
 303                 }
 304                 werror = create_response_rr(question, &recs[ri], &ans, &ai);
 305                 if (!W_ERROR_IS_OK(werror)) {
 306                         return werror;
 307                 }
 308         }
 309
 310         if (ai == 0) {
 311                 return DNS_ERR(NAME_ERROR);
 312         }
 313
 314         *ancount = ai;
 315         *answers = ans;
 316
 317         return WERR_OK;
 318 }
 319
 320 struct dns_server_process_query_state {
 321         struct dns_res_rec *answers;
 322         uint16_t ancount;
 323         struct dns_res_rec *nsrecs;
 324         uint16_t nscount;
 325         struct dns_res_rec *additional;
 326         uint16_t arcount;
 327 };
 328
 329 static void dns_server_process_query_got_response(struct tevent_req *subreq);
 330
 331 struct tevent_req *dns_server_process_query_send(
 332         TALLOC_CTX *mem_ctx, struct tevent_context *ev,
 333         struct dns_server *dns, struct dns_request_state *req_state,
 334         const struct dns_name_packet *in)
 335 {
 336         struct tevent_req *req, *subreq;
 337         struct dns_server_process_query_state *state;
 338
 339         req = tevent_req_create(mem_ctx, &state,
 340                                 struct dns_server_process_query_state);
 341         if (req == NULL) {
 342                 return NULL;
 343         }
 344         if (in->qdcount != 1) {
 345                 tevent_req_werror(req, DNS_ERR(FORMAT_ERROR));
 346                 return tevent_req_post(req, ev);
 347         }
 348
 349         /* Windows returns NOT_IMPLEMENTED on this as well */
 350         if (in->questions[0].question_class == DNS_QCLASS_NONE) {
 351                 tevent_req_werror(req, DNS_ERR(NOT_IMPLEMENTED));
 352                 return tevent_req_post(req, ev);
 353         }
 354
 355         if (dns_authorative_for_zone(dns, in->questions[0].name)) {
 356                 WERROR err;
 357
 358                 req_state->flags |= DNS_FLAG_AUTHORITATIVE;
 359                 err = handle_question(dns, state, &in->questions[0],
 360                                       &state->answers, &state->ancount);
 361                 if (tevent_req_werror(req, err)) {
 362                         return tevent_req_post(req, ev);
 363                 }
 364                 tevent_req_done(req);
 365                 return tevent_req_post(req, ev);
 366         }
 367
 368         if ((req_state->flags & DNS_FLAG_RECURSION_DESIRED) &&
 369             (req_state->flags & DNS_FLAG_RECURSION_AVAIL)) {
 370                 DEBUG(2, ("Not authoritative for '%s', forwarding\n",
 371                           in->questions[0].name));
 372
 373                 subreq = ask_forwarder_send(
 374                         state, ev, lpcfg_dns_forwarder(dns->task->lp_ctx),
 375                         &in->questions[0]);
 376                 if (tevent_req_nomem(subreq, req)) {
 377                         return tevent_req_post(req, ev);
 378                 }
 379                 tevent_req_set_callback(
 380                         subreq, dns_server_process_query_got_response, req);
 381                 return req;
 382         }
 383
 384         tevent_req_werror(req, DNS_ERR(NAME_ERROR));
 385         return tevent_req_post(req, ev);
 386 }
 387
 388 static void dns_server_process_query_got_response(struct tevent_req *subreq)
 389 {
 390         struct tevent_req *req = tevent_req_callback_data(
 391                 subreq, struct tevent_req);
 392         struct dns_server_process_query_state *state = tevent_req_data(
 393                 req, struct dns_server_process_query_state);
 394         WERROR err;
 395
 396         err = ask_forwarder_recv(subreq, state,
 397                                  &state->answers, &state->ancount,
 398                                  &state->nsrecs, &state->nscount,
 399                                  &state->additional, &state->arcount);
 400         TALLOC_FREE(subreq);
 401         if (tevent_req_werror(req, err)) {
 402                 return;
 403         }
 404         tevent_req_done(req);
 405 }
 406
 407 WERROR dns_server_process_query_recv(
 408         struct tevent_req *req, TALLOC_CTX *mem_ctx,
 409         struct dns_res_rec **answers,    uint16_t *ancount,
 410         struct dns_res_rec **nsrecs,     uint16_t *nscount,
 411         struct dns_res_rec **additional, uint16_t *arcount)
 412 {
 413         struct dns_server_process_query_state *state = tevent_req_data(
 414                 req, struct dns_server_process_query_state);
 415         WERROR err;
 416
 417         if (tevent_req_is_werror(req, &err)) {
 418                 return err;
 419         }
 420         *answers = talloc_move(mem_ctx, &state->answers);
 421         *ancount = state->ancount;
 422         *nsrecs = talloc_move(mem_ctx, &state->nsrecs);
 423         *nscount = state->nscount;
 424         *additional = talloc_move(mem_ctx, &state->additional);
 425         *arcount = state->arcount;
 426         return WERR_OK;
 427 }