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/dlinklist.h"
  35 #include "lib/util/util_net.h"
  36 #include "lib/util/tevent_werror.h"
  37 #include "auth/auth.h"
  38 #include "auth/credentials/credentials.h"
  39 #include "auth/gensec/gensec.h"
  40
  41 #undef DBGC_CLASS
  42 #define DBGC_CLASS DBGC_DNS
  43
  44 struct forwarder_string {
  45         const char *forwarder;
  46         struct forwarder_string *prev, *next;
  47 };
  48
  49 static WERROR add_response_rr(const char *name,
  50                               const struct dnsp_DnssrvRpcRecord *rec,
  51                               struct dns_res_rec **answers)
  52 {
  53         struct dns_res_rec *ans = *answers;
  54         uint16_t ai = talloc_array_length(ans);
  55         enum ndr_err_code ndr_err;
  56
  57         if (ai == UINT16_MAX) {
  58                 return WERR_BUFFER_OVERFLOW;
  59         }
  60
  61         /*
  62          * "ans" is always non-NULL and thus its own talloc context
  63          */
  64         ans = talloc_realloc(ans, ans, struct dns_res_rec, ai+1);
  65         if (ans == NULL) {
  66                 return WERR_NOT_ENOUGH_MEMORY;
  67         }
  68
  69         ZERO_STRUCT(ans[ai]);
  70
  71         switch (rec->wType) {
  72         case DNS_QTYPE_CNAME:
  73                 ans[ai].rdata.cname_record = talloc_strdup(ans, rec->data.cname);
  74                 W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.cname_record);
  75                 break;
  76         case DNS_QTYPE_A:
  77                 ans[ai].rdata.ipv4_record = talloc_strdup(ans, rec->data.ipv4);
  78                 W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.ipv4_record);
  79                 break;
  80         case DNS_QTYPE_AAAA:
  81                 ans[ai].rdata.ipv6_record = talloc_strdup(ans, rec->data.ipv6);
  82                 W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.ipv6_record);
  83                 break;
  84         case DNS_TYPE_NS:
  85                 ans[ai].rdata.ns_record = talloc_strdup(ans, rec->data.ns);
  86                 W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.ns_record);
  87                 break;
  88         case DNS_QTYPE_SRV:
  89                 ans[ai].rdata.srv_record.priority = rec->data.srv.wPriority;
  90                 ans[ai].rdata.srv_record.weight   = rec->data.srv.wWeight;
  91                 ans[ai].rdata.srv_record.port     = rec->data.srv.wPort;
  92                 ans[ai].rdata.srv_record.target   = talloc_strdup(
  93                         ans, rec->data.srv.nameTarget);
  94                 W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.srv_record.target);
  95                 break;
  96         case DNS_QTYPE_SOA:
  97                 ans[ai].rdata.soa_record.mname   = talloc_strdup(
  98                         ans, rec->data.soa.mname);
  99                 W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.soa_record.mname);
 100                 ans[ai].rdata.soa_record.rname   = talloc_strdup(
 101                         ans, rec->data.soa.rname);
 102                 W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.soa_record.rname);
 103                 ans[ai].rdata.soa_record.serial  = rec->data.soa.serial;
 104                 ans[ai].rdata.soa_record.refresh = rec->data.soa.refresh;
 105                 ans[ai].rdata.soa_record.retry   = rec->data.soa.retry;
 106                 ans[ai].rdata.soa_record.expire  = rec->data.soa.expire;
 107                 ans[ai].rdata.soa_record.minimum = rec->data.soa.minimum;
 108                 break;
 109         case DNS_QTYPE_PTR:
 110                 ans[ai].rdata.ptr_record = talloc_strdup(ans, rec->data.ptr);
 111                 W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.ptr_record);
 112                 break;
 113         case DNS_QTYPE_MX:
 114                 ans[ai].rdata.mx_record.preference = rec->data.mx.wPriority;
 115                 ans[ai].rdata.mx_record.exchange = talloc_strdup(
 116                         ans, rec->data.mx.nameTarget);
 117                 if (ans[ai].rdata.mx_record.exchange == NULL) {
 118                         return WERR_NOT_ENOUGH_MEMORY;
 119                 }
 120                 break;
 121         case DNS_QTYPE_TXT:
 122                 ndr_err = ndr_dnsp_string_list_copy(ans,
 123                                                     &rec->data.txt,
 124                                                     &ans[ai].rdata.txt_record.txt);
 125                 if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 126                         return WERR_NOT_ENOUGH_MEMORY;
 127                 }
 128                 break;
 129         default:
 130                 DEBUG(0, ("Got unhandled type %u query.\n", rec->wType));
 131                 return DNS_ERR(NOT_IMPLEMENTED);
 132         }
 133
 134         ans[ai].name = talloc_strdup(ans, name);
 135         W_ERROR_HAVE_NO_MEMORY(ans[ai].name);
 136         ans[ai].rr_type = rec->wType;
 137         ans[ai].rr_class = DNS_QCLASS_IN;
 138         ans[ai].ttl = rec->dwTtlSeconds;
 139         ans[ai].length = UINT16_MAX;
 140
 141         *answers = ans;
 142
 143         return WERR_OK;
 144 }
 145
 146 static WERROR add_dns_res_rec(struct dns_res_rec **pdst,
 147                               const struct dns_res_rec *src)
 148 {
 149         struct dns_res_rec *dst = *pdst;
 150         uint16_t di = talloc_array_length(dst);
 151         enum ndr_err_code ndr_err;
 152
 153         if (di == UINT16_MAX) {
 154                 return WERR_BUFFER_OVERFLOW;
 155         }
 156
 157         dst = talloc_realloc(dst, dst, struct dns_res_rec, di+1);
 158         if (dst == NULL) {
 159                 return WERR_NOT_ENOUGH_MEMORY;
 160         }
 161
 162         ZERO_STRUCT(dst[di]);
 163
 164         dst[di] = (struct dns_res_rec) {
 165                 .name = talloc_strdup(dst, src->name),
 166                 .rr_type = src->rr_type,
 167                 .rr_class = src->rr_class,
 168                 .ttl = src->ttl,
 169                 .length = src->length
 170         };
 171
 172         if (dst[di].name == NULL) {
 173                 return WERR_NOT_ENOUGH_MEMORY;
 174         }
 175
 176         switch (src->rr_type) {
 177         case DNS_QTYPE_CNAME:
 178                 dst[di].rdata.cname_record = talloc_strdup(
 179                         dst, src->rdata.cname_record);
 180                 if (dst[di].rdata.cname_record == NULL) {
 181                         return WERR_NOT_ENOUGH_MEMORY;
 182                 }
 183                 break;
 184         case DNS_QTYPE_A:
 185                 dst[di].rdata.ipv4_record = talloc_strdup(
 186                         dst, src->rdata.ipv4_record);
 187                 if (dst[di].rdata.ipv4_record == NULL) {
 188                         return WERR_NOT_ENOUGH_MEMORY;
 189                 }
 190                 break;
 191         case DNS_QTYPE_AAAA:
 192                 dst[di].rdata.ipv6_record = talloc_strdup(
 193                         dst, src->rdata.ipv6_record);
 194                 if (dst[di].rdata.ipv6_record == NULL) {
 195                         return WERR_NOT_ENOUGH_MEMORY;
 196                 }
 197                 break;
 198         case DNS_TYPE_NS:
 199                 dst[di].rdata.ns_record = talloc_strdup(
 200                         dst, src->rdata.ns_record);
 201                 if (dst[di].rdata.ns_record == NULL) {
 202                         return WERR_NOT_ENOUGH_MEMORY;
 203                 }
 204                 break;
 205         case DNS_QTYPE_SRV:
 206                 dst[di].rdata.srv_record = (struct dns_srv_record) {
 207                         .priority = src->rdata.srv_record.priority,
 208                         .weight   = src->rdata.srv_record.weight,
 209                         .port     = src->rdata.srv_record.port,
 210                         .target   = talloc_strdup(
 211                                 dst, src->rdata.srv_record.target)
 212                 };
 213                 if (dst[di].rdata.srv_record.target == NULL) {
 214                         return WERR_NOT_ENOUGH_MEMORY;
 215                 }
 216                 break;
 217         case DNS_QTYPE_SOA:
 218                 dst[di].rdata.soa_record = (struct dns_soa_record) {
 219                         .mname   = talloc_strdup(
 220                                 dst, src->rdata.soa_record.mname),
 221                         .rname   = talloc_strdup(
 222                                 dst, src->rdata.soa_record.rname),
 223                         .serial  = src->rdata.soa_record.serial,
 224                         .refresh = src->rdata.soa_record.refresh,
 225                         .retry   = src->rdata.soa_record.retry,
 226                         .expire  = src->rdata.soa_record.expire,
 227                         .minimum = src->rdata.soa_record.minimum
 228                 };
 229
 230                 if ((dst[di].rdata.soa_record.mname == NULL) ||
 231                     (dst[di].rdata.soa_record.rname == NULL)) {
 232                         return WERR_NOT_ENOUGH_MEMORY;
 233                 }
 234
 235                 break;
 236         case DNS_QTYPE_PTR:
 237                 dst[di].rdata.ptr_record = talloc_strdup(
 238                         dst, src->rdata.ptr_record);
 239                 if (dst[di].rdata.ptr_record == NULL) {
 240                         return WERR_NOT_ENOUGH_MEMORY;
 241                 }
 242                 break;
 243         case DNS_QTYPE_MX:
 244                 dst[di].rdata.mx_record = (struct dns_mx_record) {
 245                         .preference = src->rdata.mx_record.preference,
 246                         .exchange   = talloc_strdup(
 247                                 src, src->rdata.mx_record.exchange)
 248                 };
 249
 250                 if (dst[di].rdata.mx_record.exchange == NULL) {
 251                         return WERR_NOT_ENOUGH_MEMORY;
 252                 }
 253                 break;
 254         case DNS_QTYPE_TXT:
 255                 ndr_err = ndr_dnsp_string_list_copy(dst,
 256                                                     &src->rdata.txt_record.txt,
 257                                                     &dst[di].rdata.txt_record.txt);
 258                 if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 259                         return WERR_NOT_ENOUGH_MEMORY;
 260                 }
 261                 break;
 262         default:
 263                 DBG_WARNING("Got unhandled type %u query.\n", src->rr_type);
 264                 return DNS_ERR(NOT_IMPLEMENTED);
 265         }
 266
 267         *pdst = dst;
 268
 269         return WERR_OK;
 270 }
 271
 272 struct ask_forwarder_state {
 273         struct tevent_context *ev;
 274         uint16_t id;
 275         struct dns_name_packet in_packet;
 276 };
 277
 278 static void ask_forwarder_done(struct tevent_req *subreq);
 279
 280 static struct tevent_req *ask_forwarder_send(
 281         TALLOC_CTX *mem_ctx, struct tevent_context *ev,
 282         struct dns_server *dns,
 283         const char *forwarder, struct dns_name_question *question)
 284 {
 285         struct tevent_req *req, *subreq;
 286         struct ask_forwarder_state *state;
 287         struct dns_res_rec *options;
 288         struct dns_name_packet out_packet = { 0, };
 289         DATA_BLOB out_blob;
 290         enum ndr_err_code ndr_err;
 291         WERROR werr;
 292
 293         req = tevent_req_create(mem_ctx, &state, struct ask_forwarder_state);
 294         if (req == NULL) {
 295                 return NULL;
 296         }
 297         state->ev = ev;
 298         generate_random_buffer((uint8_t *)&state->id, sizeof(state->id));
 299
 300         if (!is_ipaddress(forwarder)) {
 301                 DEBUG(0, ("Invalid 'dns forwarder' setting '%s', needs to be "
 302                           "an IP address\n", forwarder));
 303                 tevent_req_werror(req, DNS_ERR(NAME_ERROR));
 304                 return tevent_req_post(req, ev);
 305         }
 306
 307         out_packet.id = state->id;
 308         out_packet.operation |= DNS_OPCODE_QUERY | DNS_FLAG_RECURSION_DESIRED;
 309         out_packet.qdcount = 1;
 310         out_packet.questions = question;
 311
 312         werr = dns_generate_options(dns, state, &options);
 313         if (!W_ERROR_IS_OK(werr)) {
 314                 tevent_req_werror(req, werr);
 315                 return tevent_req_post(req, ev);
 316         }
 317
 318         out_packet.arcount = 1;
 319         out_packet.additional = options;
 320
 321         ndr_err = ndr_push_struct_blob(
 322                 &out_blob, state, &out_packet,
 323                 (ndr_push_flags_fn_t)ndr_push_dns_name_packet);
 324         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 325                 tevent_req_werror(req, DNS_ERR(SERVER_FAILURE));
 326                 return tevent_req_post(req, ev);
 327         }
 328         subreq = dns_udp_request_send(state, ev, forwarder, out_blob.data,
 329                                       out_blob.length);
 330         if (tevent_req_nomem(subreq, req)) {
 331                 return tevent_req_post(req, ev);
 332         }
 333         tevent_req_set_callback(subreq, ask_forwarder_done, req);
 334         return req;
 335 }
 336
 337 static void ask_forwarder_done(struct tevent_req *subreq)
 338 {
 339         struct tevent_req *req = tevent_req_callback_data(
 340                 subreq, struct tevent_req);
 341         struct ask_forwarder_state *state = tevent_req_data(
 342                 req, struct ask_forwarder_state);
 343         DATA_BLOB in_blob;
 344         enum ndr_err_code ndr_err;
 345         int ret;
 346
 347         ret = dns_udp_request_recv(subreq, state,
 348                                    &in_blob.data, &in_blob.length);
 349         TALLOC_FREE(subreq);
 350
 351         if (ret != 0) {
 352                 tevent_req_werror(req, unix_to_werror(ret));
 353                 return;
 354         }
 355
 356         ndr_err = ndr_pull_struct_blob(
 357                 &in_blob, state, &state->in_packet,
 358                 (ndr_pull_flags_fn_t)ndr_pull_dns_name_packet);
 359         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 360                 tevent_req_werror(req, DNS_ERR(SERVER_FAILURE));
 361                 return;
 362         }
 363         if (state->in_packet.id != state->id) {
 364                 tevent_req_werror(req, DNS_ERR(NAME_ERROR));
 365                 return;
 366         }
 367         tevent_req_done(req);
 368 }
 369
 370 static WERROR ask_forwarder_recv(
 371         struct tevent_req *req, TALLOC_CTX *mem_ctx,
 372         struct dns_res_rec **answers, uint16_t *ancount,
 373         struct dns_res_rec **nsrecs, uint16_t *nscount,
 374         struct dns_res_rec **additional, uint16_t *arcount)
 375 {
 376         struct ask_forwarder_state *state = tevent_req_data(
 377                 req, struct ask_forwarder_state);
 378         struct dns_name_packet *in_packet = &state->in_packet;
 379         WERROR err;
 380
 381         if (tevent_req_is_werror(req, &err)) {
 382                 return err;
 383         }
 384
 385         *ancount = in_packet->ancount;
 386         *answers = talloc_move(mem_ctx, &in_packet->answers);
 387
 388         *nscount = in_packet->nscount;
 389         *nsrecs = talloc_move(mem_ctx, &in_packet->nsrecs);
 390
 391         *arcount = in_packet->arcount;
 392         *additional = talloc_move(mem_ctx, &in_packet->additional);
 393
 394         return WERR_OK;
 395 }
 396
 397 static WERROR add_zone_authority_record(struct dns_server *dns,
 398                                         TALLOC_CTX *mem_ctx,
 399                                         const struct dns_name_question *question,
 400                                         struct dns_res_rec **nsrecs)
 401 {
 402         const char *zone = NULL;
 403         struct dnsp_DnssrvRpcRecord *recs;
 404         struct dns_res_rec *ns = *nsrecs;
 405         uint16_t rec_count;
 406         struct ldb_dn *dn = NULL;
 407         unsigned int ri;
 408         WERROR werror;
 409
 410         zone = dns_get_authoritative_zone(dns, question->name);
 411         DEBUG(10, ("Creating zone authority record for '%s'\n", zone));
 412
 413         werror = dns_name2dn(dns, mem_ctx, zone, &dn);
 414         if (!W_ERROR_IS_OK(werror)) {
 415                 return werror;
 416         }
 417
 418         werror = dns_lookup_records(dns, mem_ctx, dn, &recs, &rec_count);
 419         if (!W_ERROR_IS_OK(werror)) {
 420                 return werror;
 421         }
 422
 423         for (ri = 0; ri < rec_count; ri++) {
 424                 if (recs[ri].wType == DNS_TYPE_SOA) {
 425                         werror = add_response_rr(zone, &recs[ri], &ns);
 426                         if (!W_ERROR_IS_OK(werror)) {
 427                                 return werror;
 428                         }
 429                 }
 430         }
 431
 432         *nsrecs = ns;
 433
 434         return WERR_OK;
 435 }
 436
 437 static struct tevent_req *handle_authoritative_send(
 438         TALLOC_CTX *mem_ctx, struct tevent_context *ev,
 439         struct dns_server *dns, const char *forwarder,
 440         struct dns_name_question *question,
 441         struct dns_res_rec **answers, struct dns_res_rec **nsrecs);
 442 static WERROR handle_authoritative_recv(struct tevent_req *req);
 443
 444 struct handle_dnsrpcrec_state {
 445         struct dns_res_rec **answers;
 446         struct dns_res_rec **nsrecs;
 447 };
 448
 449 static void handle_dnsrpcrec_gotauth(struct tevent_req *subreq);
 450 static void handle_dnsrpcrec_gotforwarded(struct tevent_req *subreq);
 451
 452 static struct tevent_req *handle_dnsrpcrec_send(
 453         TALLOC_CTX *mem_ctx, struct tevent_context *ev,
 454         struct dns_server *dns, const char *forwarder,
 455         const struct dns_name_question *question,
 456         struct dnsp_DnssrvRpcRecord *rec,
 457         struct dns_res_rec **answers, struct dns_res_rec **nsrecs)
 458 {
 459         struct tevent_req *req, *subreq;
 460         struct handle_dnsrpcrec_state *state;
 461         struct dns_name_question *new_q;
 462         bool resolve_cname;
 463         WERROR werr;
 464
 465         req = tevent_req_create(mem_ctx, &state,
 466                                 struct handle_dnsrpcrec_state);
 467         if (req == NULL) {
 468                 return NULL;
 469         }
 470         state->answers = answers;
 471         state->nsrecs = nsrecs;
 472
 473         resolve_cname = ((rec->wType == DNS_TYPE_CNAME) &&
 474                          ((question->question_type == DNS_QTYPE_A) ||
 475                           (question->question_type == DNS_QTYPE_AAAA)));
 476
 477         if (!resolve_cname) {
 478                 if ((question->question_type != DNS_QTYPE_ALL) &&
 479                     (rec->wType !=
 480                      (enum dns_record_type) question->question_type)) {
 481                         tevent_req_done(req);
 482                         return tevent_req_post(req, ev);
 483                 }
 484
 485                 werr = add_response_rr(question->name, rec, state->answers);
 486                 if (tevent_req_werror(req, werr)) {
 487                         return tevent_req_post(req, ev);
 488                 }
 489
 490                 tevent_req_done(req);
 491                 return tevent_req_post(req, ev);
 492         }
 493
 494         werr = add_response_rr(question->name, rec, state->answers);
 495         if (tevent_req_werror(req, werr)) {
 496                 return tevent_req_post(req, ev);
 497         }
 498
 499         new_q = talloc(state, struct dns_name_question);
 500         if (tevent_req_nomem(new_q, req)) {
 501                 return tevent_req_post(req, ev);
 502         }
 503
 504         *new_q = (struct dns_name_question) {
 505                 .question_type = question->question_type,
 506                 .question_class = question->question_class,
 507                 .name = rec->data.cname
 508         };
 509
 510         if (dns_authoritative_for_zone(dns, new_q->name)) {
 511                 subreq = handle_authoritative_send(
 512                         state, ev, dns, forwarder, new_q,
 513                         state->answers, state->nsrecs);
 514                 if (tevent_req_nomem(subreq, req)) {
 515                         return tevent_req_post(req, ev);
 516                 }
 517                 tevent_req_set_callback(subreq, handle_dnsrpcrec_gotauth, req);
 518                 return req;
 519         }
 520
 521         subreq = ask_forwarder_send(state, ev, dns, forwarder, new_q);
 522         if (tevent_req_nomem(subreq, req)) {
 523                 return tevent_req_post(req, ev);
 524         }
 525         tevent_req_set_callback(subreq, handle_dnsrpcrec_gotforwarded, req);
 526
 527         return req;
 528 }
 529
 530 static void handle_dnsrpcrec_gotauth(struct tevent_req *subreq)
 531 {
 532         struct tevent_req *req = tevent_req_callback_data(
 533                 subreq, struct tevent_req);
 534         WERROR werr;
 535
 536         werr = handle_authoritative_recv(subreq);
 537         TALLOC_FREE(subreq);
 538         if (tevent_req_werror(req, werr)) {
 539                 return;
 540         }
 541         tevent_req_done(req);
 542 }
 543
 544 static void handle_dnsrpcrec_gotforwarded(struct tevent_req *subreq)
 545 {
 546         struct tevent_req *req = tevent_req_callback_data(
 547                 subreq, struct tevent_req);
 548         struct handle_dnsrpcrec_state *state = tevent_req_data(
 549                 req, struct handle_dnsrpcrec_state);
 550         struct dns_res_rec *answers, *nsrecs, *additional;
 551         uint16_t ancount = 0;
 552         uint16_t nscount = 0;
 553         uint16_t arcount = 0;
 554         uint16_t i;
 555         WERROR werr;
 556
 557         werr = ask_forwarder_recv(subreq, state, &answers, &ancount,
 558                                   &nsrecs, &nscount, &additional, &arcount);
 559         if (tevent_req_werror(req, werr)) {
 560                 return;
 561         }
 562
 563         for (i=0; i<ancount; i++) {
 564                 werr = add_dns_res_rec(state->answers, &answers[i]);
 565                 if (tevent_req_werror(req, werr)) {
 566                         return;
 567                 }
 568         }
 569
 570         for (i=0; i<nscount; i++) {
 571                 werr = add_dns_res_rec(state->nsrecs, &nsrecs[i]);
 572                 if (tevent_req_werror(req, werr)) {
 573                         return;
 574                 }
 575         }
 576
 577         tevent_req_done(req);
 578 }
 579
 580 static WERROR handle_dnsrpcrec_recv(struct tevent_req *req)
 581 {
 582         return tevent_req_simple_recv_werror(req);
 583 }
 584
 585 struct handle_authoritative_state {
 586         struct tevent_context *ev;
 587         struct dns_server *dns;
 588         struct dns_name_question *question;
 589         const char *forwarder;
 590
 591         struct dnsp_DnssrvRpcRecord *recs;
 592         uint16_t rec_count;
 593         uint16_t recs_done;
 594
 595         struct dns_res_rec **answers;
 596         struct dns_res_rec **nsrecs;
 597 };
 598
 599 static void handle_authoritative_done(struct tevent_req *subreq);
 600
 601 static struct tevent_req *handle_authoritative_send(
 602         TALLOC_CTX *mem_ctx, struct tevent_context *ev,
 603         struct dns_server *dns, const char *forwarder,
 604         struct dns_name_question *question,
 605         struct dns_res_rec **answers, struct dns_res_rec **nsrecs)
 606 {
 607         struct tevent_req *req, *subreq;
 608         struct handle_authoritative_state *state;
 609         struct ldb_dn *dn = NULL;
 610         WERROR werr;
 611
 612         req = tevent_req_create(mem_ctx, &state,
 613                                 struct handle_authoritative_state);
 614         if (req == NULL) {
 615                 return NULL;
 616         }
 617         state->ev = ev;
 618         state->dns = dns;
 619         state->question = question;
 620         state->forwarder = forwarder;
 621         state->answers = answers;
 622         state->nsrecs = nsrecs;
 623
 624         werr = dns_name2dn(dns, state, question->name, &dn);
 625         if (tevent_req_werror(req, werr)) {
 626                 return tevent_req_post(req, ev);
 627         }
 628
 629         werr = dns_lookup_records(dns, state, dn, &state->recs,
 630                                   &state->rec_count);
 631         TALLOC_FREE(dn);
 632         if (tevent_req_werror(req, werr)) {
 633                 return tevent_req_post(req, ev);
 634         }
 635
 636         if (state->rec_count == 0) {
 637                 tevent_req_werror(req, DNS_ERR(NAME_ERROR));
 638                 return tevent_req_post(req, ev);
 639         }
 640
 641         subreq = handle_dnsrpcrec_send(
 642                 state, state->ev, state->dns, state->forwarder,
 643                 state->question, &state->recs[state->recs_done],
 644                 state->answers, state->nsrecs);
 645         if (tevent_req_nomem(subreq, req)) {
 646                 return tevent_req_post(req, ev);
 647         }
 648         tevent_req_set_callback(subreq, handle_authoritative_done, req);
 649         return req;
 650 }
 651
 652 static void handle_authoritative_done(struct tevent_req *subreq)
 653 {
 654         struct tevent_req *req = tevent_req_callback_data(
 655                 subreq, struct tevent_req);
 656         struct handle_authoritative_state *state = tevent_req_data(
 657                 req, struct handle_authoritative_state);
 658         WERROR werr;
 659
 660         werr = handle_dnsrpcrec_recv(subreq);
 661         TALLOC_FREE(subreq);
 662         if (tevent_req_werror(req, werr)) {
 663                 return;
 664         }
 665
 666         state->recs_done += 1;
 667
 668         if (state->recs_done == state->rec_count) {
 669                 tevent_req_done(req);
 670                 return;
 671         }
 672
 673         subreq = handle_dnsrpcrec_send(
 674                 state, state->ev, state->dns, state->forwarder,
 675                 state->question, &state->recs[state->recs_done],
 676                 state->answers, state->nsrecs);
 677         if (tevent_req_nomem(subreq, req)) {
 678                 return;
 679         }
 680         tevent_req_set_callback(subreq, handle_authoritative_done, req);
 681 }
 682
 683 static WERROR handle_authoritative_recv(struct tevent_req *req)
 684 {
 685         struct handle_authoritative_state *state = tevent_req_data(
 686                 req, struct handle_authoritative_state);
 687         WERROR werr;
 688
 689         if (tevent_req_is_werror(req, &werr)) {
 690                 return werr;
 691         }
 692
 693         werr = add_zone_authority_record(state->dns, state, state->question,
 694                                          state->nsrecs);
 695         if (!W_ERROR_IS_OK(werr)) {
 696                 return werr;
 697         }
 698
 699         return WERR_OK;
 700 }
 701
 702 static NTSTATUS create_tkey(struct dns_server *dns,
 703                             const char* name,
 704                             const char* algorithm,
 705                             struct dns_server_tkey **tkey)
 706 {
 707         NTSTATUS status;
 708         struct dns_server_tkey_store *store = dns->tkeys;
 709         struct dns_server_tkey *k = talloc_zero(store, struct dns_server_tkey);
 710
 711         if (k == NULL) {
 712                 return NT_STATUS_NO_MEMORY;
 713         }
 714
 715         k->name = talloc_strdup(k, name);
 716
 717         if (k->name  == NULL) {
 718                 return NT_STATUS_NO_MEMORY;
 719         }
 720
 721         k->algorithm = talloc_strdup(k, algorithm);
 722         if (k->algorithm == NULL) {
 723                 return NT_STATUS_NO_MEMORY;
 724         }
 725
 726         status = samba_server_gensec_start(k,
 727                                            dns->task->event_ctx,
 728                                            dns->task->msg_ctx,
 729                                            dns->task->lp_ctx,
 730                                            dns->server_credentials,
 731                                            "dns",
 732                                            &k->gensec);
 733         if (!NT_STATUS_IS_OK(status)) {
 734                 DEBUG(1, ("Failed to start GENSEC server code: %s\n", nt_errstr(status)));
 735                 *tkey = NULL;
 736                 return status;
 737         }
 738
 739         gensec_want_feature(k->gensec, GENSEC_FEATURE_SIGN);
 740
 741         status = gensec_start_mech_by_oid(k->gensec, GENSEC_OID_SPNEGO);
 742
 743         if (!NT_STATUS_IS_OK(status)) {
 744                 DEBUG(1, ("Failed to start GENSEC server code: %s\n",
 745                           nt_errstr(status)));
 746                 *tkey = NULL;
 747                 return status;
 748         }
 749
 750         if (store->tkeys[store->next_idx] != NULL) {
 751                 TALLOC_FREE(store->tkeys[store->next_idx]);
 752         }
 753
 754         store->tkeys[store->next_idx] = k;
 755         (store->next_idx)++;
 756         store->next_idx %= store->size;
 757
 758         *tkey = k;
 759         return NT_STATUS_OK;
 760 }
 761
 762 static NTSTATUS accept_gss_ticket(TALLOC_CTX *mem_ctx,
 763                                   struct dns_server *dns,
 764                                   struct dns_server_tkey *tkey,
 765                                   const DATA_BLOB *key,
 766                                   DATA_BLOB *reply,
 767                                   uint16_t *dns_auth_error)
 768 {
 769         NTSTATUS status;
 770
 771         status = gensec_update_ev(tkey->gensec, mem_ctx, dns->task->event_ctx,
 772                                   *key, reply);
 773
 774         if (NT_STATUS_EQUAL(NT_STATUS_MORE_PROCESSING_REQUIRED, status)) {
 775                 *dns_auth_error = DNS_RCODE_OK;
 776                 return status;
 777         }
 778
 779         if (NT_STATUS_IS_OK(status)) {
 780
 781                 status = gensec_session_info(tkey->gensec, tkey, &tkey->session_info);
 782                 if (!NT_STATUS_IS_OK(status)) {
 783                         *dns_auth_error = DNS_RCODE_BADKEY;
 784                         return status;
 785                 }
 786                 *dns_auth_error = DNS_RCODE_OK;
 787         }
 788
 789         return status;
 790 }
 791
 792 static WERROR handle_tkey(struct dns_server *dns,
 793                           TALLOC_CTX *mem_ctx,
 794                           const struct dns_name_packet *in,
 795                           struct dns_request_state *state,
 796                           struct dns_res_rec **answers,
 797                           uint16_t *ancount)
 798 {
 799         struct dns_res_rec *in_tkey = NULL;
 800         struct dns_res_rec *ret_tkey;
 801         uint16_t i;
 802
 803         for (i = 0; i < in->arcount; i++) {
 804                 if (in->additional[i].rr_type == DNS_QTYPE_TKEY) {
 805                         in_tkey = &in->additional[i];
 806                         break;
 807                 }
 808         }
 809
 810         /* If this is a TKEY query, it should have a TKEY RR.
 811          * Behaviour is not really specified in RFC 2930 or RFC 3645, but
 812          * FORMAT_ERROR seems to be what BIND uses .*/
 813         if (in_tkey == NULL) {
 814                 return DNS_ERR(FORMAT_ERROR);
 815         }
 816
 817         ret_tkey = talloc_zero(mem_ctx, struct dns_res_rec);
 818         if (ret_tkey == NULL) {
 819                 return WERR_NOT_ENOUGH_MEMORY;
 820         }
 821
 822         ret_tkey->name = talloc_strdup(ret_tkey, in_tkey->name);
 823         if (ret_tkey->name == NULL) {
 824                 return WERR_NOT_ENOUGH_MEMORY;
 825         }
 826
 827         ret_tkey->rr_type = DNS_QTYPE_TKEY;
 828         ret_tkey->rr_class = DNS_QCLASS_ANY;
 829         ret_tkey->length = UINT16_MAX;
 830
 831         ret_tkey->rdata.tkey_record.algorithm = talloc_strdup(ret_tkey,
 832                         in_tkey->rdata.tkey_record.algorithm);
 833         if (ret_tkey->rdata.tkey_record.algorithm  == NULL) {
 834                 return WERR_NOT_ENOUGH_MEMORY;
 835         }
 836
 837         ret_tkey->rdata.tkey_record.inception = in_tkey->rdata.tkey_record.inception;
 838         ret_tkey->rdata.tkey_record.expiration = in_tkey->rdata.tkey_record.expiration;
 839         ret_tkey->rdata.tkey_record.mode = in_tkey->rdata.tkey_record.mode;
 840
 841         switch (in_tkey->rdata.tkey_record.mode) {
 842         case DNS_TKEY_MODE_DH:
 843                 /* FIXME: According to RFC 2930, we MUST support this, but we don't.
 844                  * Still, claim it's a bad key instead of a bad mode */
 845                 ret_tkey->rdata.tkey_record.error = DNS_RCODE_BADKEY;
 846                 break;
 847         case DNS_TKEY_MODE_GSSAPI: {
 848                 NTSTATUS status;
 849                 struct dns_server_tkey *tkey;
 850                 DATA_BLOB key;
 851                 DATA_BLOB reply;
 852
 853                 tkey = dns_find_tkey(dns->tkeys, in->questions[0].name);
 854                 if (tkey != NULL && tkey->complete) {
 855                         /* TODO: check if the key is still valid */
 856                         DEBUG(1, ("Rejecting tkey negotiation for already established key\n"));
 857                         ret_tkey->rdata.tkey_record.error = DNS_RCODE_BADNAME;
 858                         break;
 859                 }
 860
 861                 if (tkey == NULL) {
 862                         status  = create_tkey(dns, in->questions[0].name,
 863                                               in_tkey->rdata.tkey_record.algorithm,
 864                                               &tkey);
 865                         if (!NT_STATUS_IS_OK(status)) {
 866                                 ret_tkey->rdata.tkey_record.error = DNS_RCODE_BADKEY;
 867                                 return ntstatus_to_werror(status);
 868                         }
 869                 }
 870
 871                 key.data = in_tkey->rdata.tkey_record.key_data;
 872                 key.length = in_tkey->rdata.tkey_record.key_size;
 873
 874                 status = accept_gss_ticket(ret_tkey, dns, tkey, &key, &reply,
 875                                            &ret_tkey->rdata.tkey_record.error);
 876                 if (NT_STATUS_EQUAL(status, NT_STATUS_MORE_PROCESSING_REQUIRED)) {
 877                         DEBUG(1, ("More processing required\n"));
 878                         ret_tkey->rdata.tkey_record.error = DNS_RCODE_BADKEY;
 879                 } else if (NT_STATUS_IS_OK(status)) {
 880                         DEBUG(1, ("Tkey handshake completed\n"));
 881                         ret_tkey->rdata.tkey_record.key_size = reply.length;
 882                         ret_tkey->rdata.tkey_record.key_data = talloc_memdup(ret_tkey,
 883                                                                 reply.data,
 884                                                                 reply.length);
 885                         state->sign = true;
 886                         state->key_name = talloc_strdup(state->mem_ctx, tkey->name);
 887                         if (state->key_name == NULL) {
 888                                 return WERR_NOT_ENOUGH_MEMORY;
 889                         }
 890                 } else {
 891                         DEBUG(1, ("GSS key negotiation returned %s\n", nt_errstr(status)));
 892                         ret_tkey->rdata.tkey_record.error = DNS_RCODE_BADKEY;
 893                 }
 894
 895                 break;
 896                 }
 897         case DNS_TKEY_MODE_DELETE:
 898                 /* TODO: implement me */
 899                 DEBUG(1, ("Should delete tkey here\n"));
 900                 ret_tkey->rdata.tkey_record.error = DNS_RCODE_OK;
 901                 break;
 902         case DNS_TKEY_MODE_NULL:
 903         case DNS_TKEY_MODE_SERVER:
 904         case DNS_TKEY_MODE_CLIENT:
 905         case DNS_TKEY_MODE_LAST:
 906                 /* We don't have to implement these, return a mode error */
 907                 ret_tkey->rdata.tkey_record.error = DNS_RCODE_BADMODE;
 908                 break;
 909         default:
 910                 DEBUG(1, ("Unsupported TKEY mode %d\n",
 911                       in_tkey->rdata.tkey_record.mode));
 912         }
 913
 914         *answers = ret_tkey;
 915         *ancount = 1;
 916
 917         return WERR_OK;
 918 }
 919
 920 struct dns_server_process_query_state {
 921         struct tevent_context *ev;
 922         struct dns_server *dns;
 923         struct dns_name_question *question;
 924
 925         struct dns_res_rec *answers;
 926         uint16_t ancount;
 927         struct dns_res_rec *nsrecs;
 928         uint16_t nscount;
 929         struct dns_res_rec *additional;
 930         uint16_t arcount;
 931         struct forwarder_string *forwarders;
 932 };
 933
 934 static void dns_server_process_query_got_auth(struct tevent_req *subreq);
 935 static void dns_server_process_query_got_response(struct tevent_req *subreq);
 936
 937 struct tevent_req *dns_server_process_query_send(
 938         TALLOC_CTX *mem_ctx, struct tevent_context *ev,
 939         struct dns_server *dns, struct dns_request_state *req_state,
 940         const struct dns_name_packet *in)
 941 {
 942         struct tevent_req *req, *subreq;
 943         struct dns_server_process_query_state *state;
 944         const char **forwarders = NULL;
 945         unsigned int i;
 946
 947         req = tevent_req_create(mem_ctx, &state,
 948                                 struct dns_server_process_query_state);
 949         if (req == NULL) {
 950                 return NULL;
 951         }
 952         if (in->qdcount != 1) {
 953                 tevent_req_werror(req, DNS_ERR(FORMAT_ERROR));
 954                 return tevent_req_post(req, ev);
 955         }
 956
 957         /* Windows returns NOT_IMPLEMENTED on this as well */
 958         if (in->questions[0].question_class == DNS_QCLASS_NONE) {
 959                 tevent_req_werror(req, DNS_ERR(NOT_IMPLEMENTED));
 960                 return tevent_req_post(req, ev);
 961         }
 962
 963         if (in->questions[0].question_type == DNS_QTYPE_TKEY) {
 964                 WERROR err;
 965
 966                 err = handle_tkey(dns, state, in, req_state,
 967                                   &state->answers, &state->ancount);
 968                 if (tevent_req_werror(req, err)) {
 969                         return tevent_req_post(req, ev);
 970                 }
 971                 tevent_req_done(req);
 972                 return tevent_req_post(req, ev);
 973         }
 974
 975         state->dns = dns;
 976         state->ev = ev;
 977         state->question = &in->questions[0];
 978
 979         forwarders = lpcfg_dns_forwarder(dns->task->lp_ctx);
 980         for (i = 0; forwarders != NULL && forwarders[i] != NULL; i++) {
 981                 struct forwarder_string *f = talloc_zero(state,
 982                                                          struct forwarder_string);
 983                 f->forwarder = forwarders[i];
 984                 DLIST_ADD_END(state->forwarders, f);
 985         }
 986
 987         if (dns_authoritative_for_zone(dns, in->questions[0].name)) {
 988
 989                 req_state->flags |= DNS_FLAG_AUTHORITATIVE;
 990
 991                 /*
 992                  * Initialize the response arrays, so that we can use
 993                  * them as their own talloc contexts when doing the
 994                  * realloc
 995                  */
 996                 state->answers = talloc_array(state, struct dns_res_rec, 0);
 997                 if (tevent_req_nomem(state->answers, req)) {
 998                         return tevent_req_post(req, ev);
 999                 }
1000                 state->nsrecs = talloc_array(state, struct dns_res_rec, 0);
1001                 if (tevent_req_nomem(state->nsrecs, req)) {
1002                         return tevent_req_post(req, ev);
1003                 }
1004
1005                 subreq = handle_authoritative_send(
1006                         state, ev, dns, (forwarders == NULL ? NULL : forwarders[0]),
1007                         &in->questions[0], &state->answers, &state->nsrecs);
1008                 if (tevent_req_nomem(subreq, req)) {
1009                         return tevent_req_post(req, ev);
1010                 }
1011                 tevent_req_set_callback(
1012                         subreq, dns_server_process_query_got_auth, req);
1013                 return req;
1014         }
1015
1016         if ((req_state->flags & DNS_FLAG_RECURSION_DESIRED) &&
1017             (req_state->flags & DNS_FLAG_RECURSION_AVAIL)) {
1018                 DEBUG(2, ("Not authoritative for '%s', forwarding\n",
1019                           in->questions[0].name));
1020
1021                 subreq = ask_forwarder_send(state, ev, dns,
1022                                             (forwarders == NULL ? NULL : forwarders[0]),
1023                                             &in->questions[0]);
1024                 if (tevent_req_nomem(subreq, req)) {
1025                         return tevent_req_post(req, ev);
1026                 }
1027                 tevent_req_set_callback(
1028                         subreq, dns_server_process_query_got_response, req);
1029                 return req;
1030         }
1031
1032         tevent_req_werror(req, DNS_ERR(NAME_ERROR));
1033         return tevent_req_post(req, ev);
1034 }
1035
1036 static void dns_server_process_query_got_response(struct tevent_req *subreq)
1037 {
1038         struct tevent_req *req = tevent_req_callback_data(
1039                 subreq, struct tevent_req);
1040         struct dns_server_process_query_state *state = tevent_req_data(
1041                 req, struct dns_server_process_query_state);
1042         WERROR werr;
1043
1044         werr = ask_forwarder_recv(subreq, state,
1045                                   &state->answers, &state->ancount,
1046                                   &state->nsrecs, &state->nscount,
1047                                   &state->additional, &state->arcount);
1048         TALLOC_FREE(subreq);
1049
1050         /* If you get an error, attempt a different forwarder */
1051         if (!W_ERROR_IS_OK(werr)) {
1052                 if (state->forwarders != NULL) {
1053                         DLIST_REMOVE(state->forwarders, state->forwarders);
1054                 }
1055
1056                 /* If you have run out of forwarders, simply finish */
1057                 if (state->forwarders == NULL) {
1058                         tevent_req_werror(req, werr);
1059                         return;
1060                 }
1061
1062                 DEBUG(5, ("DNS query returned %s, trying another forwarder.\n",
1063                           win_errstr(werr)));
1064                 subreq = ask_forwarder_send(state, state->ev, state->dns,
1065                                             state->forwarders->forwarder,
1066                                             state->question);
1067
1068                 if (tevent_req_nomem(subreq, req)) {
1069                         return;
1070                 }
1071
1072                 tevent_req_set_callback(subreq,
1073                                         dns_server_process_query_got_response,
1074                                         req);
1075                 return;
1076         }
1077
1078         tevent_req_done(req);
1079 }
1080
1081 static void dns_server_process_query_got_auth(struct tevent_req *subreq)
1082 {
1083         struct tevent_req *req = tevent_req_callback_data(
1084                 subreq, struct tevent_req);
1085         struct dns_server_process_query_state *state = tevent_req_data(
1086                 req, struct dns_server_process_query_state);
1087         WERROR werr;
1088
1089         werr = handle_authoritative_recv(subreq);
1090         TALLOC_FREE(subreq);
1091
1092         /* If you get an error, attempt a different forwarder */
1093         if (!W_ERROR_IS_OK(werr)) {
1094                 if (state->forwarders != NULL) {
1095                         DLIST_REMOVE(state->forwarders, state->forwarders);
1096                 }
1097
1098                 /* If you have run out of forwarders, simply finish */
1099                 if (state->forwarders == NULL) {
1100                         tevent_req_werror(req, werr);
1101                         return;
1102                 }
1103
1104                 DEBUG(5, ("Error: %s, trying a different forwarder.\n",
1105                           win_errstr(werr)));
1106                 subreq = handle_authoritative_send(state, state->ev, state->dns,
1107                                                    state->forwarders->forwarder,
1108                                                    state->question, &state->answers,
1109                                                    &state->nsrecs);
1110
1111                 if (tevent_req_nomem(subreq, req)) {
1112                         return;
1113                 }
1114
1115                 tevent_req_set_callback(subreq,
1116                                         dns_server_process_query_got_auth,
1117                                         req);
1118                 return;
1119         }
1120
1121         state->ancount = talloc_array_length(state->answers);
1122         state->nscount = talloc_array_length(state->nsrecs);
1123         state->arcount = talloc_array_length(state->additional);
1124
1125         tevent_req_done(req);
1126 }
1127
1128 WERROR dns_server_process_query_recv(
1129         struct tevent_req *req, TALLOC_CTX *mem_ctx,
1130         struct dns_res_rec **answers,    uint16_t *ancount,
1131         struct dns_res_rec **nsrecs,     uint16_t *nscount,
1132         struct dns_res_rec **additional, uint16_t *arcount)
1133 {
1134         struct dns_server_process_query_state *state = tevent_req_data(
1135                 req, struct dns_server_process_query_state);
1136         WERROR err = WERR_OK;
1137
1138         if (tevent_req_is_werror(req, &err)) {
1139
1140                 if ((!W_ERROR_EQUAL(err, DNS_ERR(NAME_ERROR))) &&
1141                     (!W_ERROR_EQUAL(err, WERR_DNS_ERROR_NAME_DOES_NOT_EXIST))) {
1142                         return err;
1143                 }
1144         }
1145         *answers = talloc_move(mem_ctx, &state->answers);
1146         *ancount = state->ancount;
1147         *nsrecs = talloc_move(mem_ctx, &state->nsrecs);
1148         *nscount = state->nscount;
1149         *additional = talloc_move(mem_ctx, &state->additional);
1150         *arcount = state->arcount;
1151         return err;
1152 }