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                 if (ans[ai].rdata.cname_record == NULL) {
  52                         return WERR_NOMEM;
  53                 }
  54                 break;
  55         case DNS_QTYPE_A:
  56                 ans[ai].rdata.ipv4_record = talloc_strdup(ans, rec->data.ipv4);
  57                 if (ans[ai].rdata.ipv4_record == NULL) {
  58                         return WERR_NOMEM;
  59                 }
  60                 break;
  61         case DNS_QTYPE_AAAA:
  62                 ans[ai].rdata.ipv6_record = talloc_strdup(ans, rec->data.ipv6);
  63                 W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.ipv6_record);
  64                 break;
  65         case DNS_TYPE_NS:
  66                 ans[ai].rdata.ns_record = rec->data.ns;
  67                 break;
  68         case DNS_QTYPE_SRV:
  69                 ans[ai].rdata.srv_record.priority = rec->data.srv.wPriority;
  70                 ans[ai].rdata.srv_record.weight   = rec->data.srv.wWeight;
  71                 ans[ai].rdata.srv_record.port     = rec->data.srv.wPort;
  72                 ans[ai].rdata.srv_record.target   = talloc_strdup(
  73                         ans, rec->data.srv.nameTarget);
  74                 if (ans[ai].rdata.srv_record.target == NULL) {
  75                         return WERR_NOMEM;
  76                 }
  77                 break;
  78         case DNS_QTYPE_SOA:
  79                 ans[ai].rdata.soa_record.mname   = talloc_strdup(
  80                         ans, rec->data.soa.mname);
  81                 if (ans[ai].rdata.soa_record.mname == NULL) {
  82                         return WERR_NOMEM;
  83                 }
  84                 ans[ai].rdata.soa_record.rname   = talloc_strdup(
  85                         ans, rec->data.soa.rname);
  86                 if (ans[ai].rdata.soa_record.rname == NULL) {
  87                         return WERR_NOMEM;
  88                 }
  89                 ans[ai].rdata.soa_record.serial  = rec->data.soa.serial;
  90                 ans[ai].rdata.soa_record.refresh = rec->data.soa.refresh;
  91                 ans[ai].rdata.soa_record.retry   = rec->data.soa.retry;
  92                 ans[ai].rdata.soa_record.expire  = rec->data.soa.expire;
  93                 ans[ai].rdata.soa_record.minimum = rec->data.soa.minimum;
  94                 break;
  95         case DNS_QTYPE_PTR:
  96                 ans[ai].rdata.ptr_record = talloc_strdup(ans, rec->data.ptr);
  97                 break;
  98         case DNS_QTYPE_TXT:
  99                 tmp = talloc_asprintf(ans, "\"%s\"", rec->data.txt.str[0]);
 100                 if (tmp == NULL) {
 101                         return WERR_NOMEM;
 102                 }
 103                 for (i=1; i<rec->data.txt.count; i++) {
 104                         tmp = talloc_asprintf_append_buffer(
 105                                 tmp, " \"%s\"", rec->data.txt.str[i]);
 106                         if (tmp == NULL) {
 107                                 return WERR_NOMEM;
 108                         }
 109                 }
 110                 ans[ai].rdata.txt_record.txt = tmp;
 111                 break;
 112         default:
 113                 DEBUG(0, ("Got unhandled type %u query.\n", rec->wType));
 114                 return DNS_ERR(NOT_IMPLEMENTED);
 115         }
 116
 117         ans[ai].name = talloc_strdup(ans, question->name);
 118         if (ans[ai].name == NULL) {
 119                 return WERR_NOMEM;
 120         }
 121         ans[ai].rr_type = rec->wType;
 122         ans[ai].rr_class = DNS_QCLASS_IN;
 123         ans[ai].ttl = rec->dwTtlSeconds;
 124         ans[ai].length = UINT16_MAX;
 125         ai++;
 126
 127         *answers = ans;
 128         *ancount = ai;
 129
 130         return WERR_OK;
 131 }
 132
 133 struct ask_forwarder_state {
 134         struct tevent_context *ev;
 135         uint16_t id;
 136         struct dns_name_packet in_packet;
 137 };
 138
 139 static void ask_forwarder_done(struct tevent_req *subreq);
 140
 141 static struct tevent_req *ask_forwarder_send(
 142         TALLOC_CTX *mem_ctx, struct tevent_context *ev,
 143         const char *forwarder, struct dns_name_question *question)
 144 {
 145         struct tevent_req *req, *subreq;
 146         struct ask_forwarder_state *state;
 147         struct dns_name_packet out_packet = { 0, };
 148         DATA_BLOB out_blob;
 149         enum ndr_err_code ndr_err;
 150
 151         req = tevent_req_create(mem_ctx, &state, struct ask_forwarder_state);
 152         if (req == NULL) {
 153                 return NULL;
 154         }
 155         state->ev = ev;
 156         generate_random_buffer((uint8_t *)&state->id, sizeof(state->id));
 157
 158         if (!is_ipaddress(forwarder)) {
 159                 DEBUG(0, ("Invalid 'dns forwarder' setting '%s', needs to be "
 160                           "an IP address\n", forwarder));
 161                 tevent_req_werror(req, DNS_ERR(NAME_ERROR));
 162                 return tevent_req_post(req, ev);
 163         }
 164
 165         out_packet.id = state->id;
 166         out_packet.operation |= DNS_OPCODE_QUERY | DNS_FLAG_RECURSION_DESIRED;
 167         out_packet.qdcount = 1;
 168         out_packet.questions = question;
 169
 170         ndr_err = ndr_push_struct_blob(
 171                 &out_blob, state, &out_packet,
 172                 (ndr_push_flags_fn_t)ndr_push_dns_name_packet);
 173         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 174                 tevent_req_werror(req, DNS_ERR(SERVER_FAILURE));
 175                 return tevent_req_post(req, ev);
 176         }
 177         subreq = dns_udp_request_send(state, ev, forwarder, out_blob.data,
 178                                       out_blob.length);
 179         if (tevent_req_nomem(subreq, req)) {
 180                 return tevent_req_post(req, ev);
 181         }
 182         tevent_req_set_callback(subreq, ask_forwarder_done, req);
 183         return req;
 184 }
 185
 186 static void ask_forwarder_done(struct tevent_req *subreq)
 187 {
 188         struct tevent_req *req = tevent_req_callback_data(
 189                 subreq, struct tevent_req);
 190         struct ask_forwarder_state *state = tevent_req_data(
 191                 req, struct ask_forwarder_state);
 192         DATA_BLOB in_blob;
 193         enum ndr_err_code ndr_err;
 194         WERROR ret;
 195
 196         ret = dns_udp_request_recv(subreq, state,
 197                                    &in_blob.data, &in_blob.length);
 198         TALLOC_FREE(subreq);
 199         if (tevent_req_werror(req, ret)) {
 200                 return;
 201         }
 202
 203         ndr_err = ndr_pull_struct_blob(
 204                 &in_blob, state, &state->in_packet,
 205                 (ndr_pull_flags_fn_t)ndr_pull_dns_name_packet);
 206         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 207                 tevent_req_werror(req, DNS_ERR(SERVER_FAILURE));
 208                 return;
 209         }
 210         if (state->in_packet.id != state->id) {
 211                 tevent_req_werror(req, DNS_ERR(NAME_ERROR));
 212                 return;
 213         }
 214         tevent_req_done(req);
 215 }
 216
 217 static WERROR ask_forwarder_recv(
 218         struct tevent_req *req, TALLOC_CTX *mem_ctx,
 219         struct dns_res_rec **answers, uint16_t *ancount,
 220         struct dns_res_rec **nsrecs, uint16_t *nscount,
 221         struct dns_res_rec **additional, uint16_t *arcount)
 222 {
 223         struct ask_forwarder_state *state = tevent_req_data(
 224                 req, struct ask_forwarder_state);
 225         struct dns_name_packet *in_packet = &state->in_packet;
 226         WERROR err;
 227
 228         if (tevent_req_is_werror(req, &err)) {
 229                 return err;
 230         }
 231
 232         *ancount = in_packet->ancount;
 233         *answers = talloc_move(mem_ctx, &in_packet->answers);
 234
 235         *nscount = in_packet->nscount;
 236         *nsrecs = talloc_move(mem_ctx, &in_packet->nsrecs);
 237
 238         *arcount = in_packet->arcount;
 239         *additional = talloc_move(mem_ctx, &in_packet->additional);
 240
 241         return WERR_OK;
 242 }
 243
 244 static WERROR handle_question(struct dns_server *dns,
 245                               TALLOC_CTX *mem_ctx,
 246                               const struct dns_name_question *question,
 247                               struct dns_res_rec **answers, uint16_t *ancount)
 248 {
 249         struct dns_res_rec *ans;
 250         WERROR werror;
 251         unsigned int ri;
 252         struct dnsp_DnssrvRpcRecord *recs;
 253         uint16_t rec_count, ai = 0;
 254         struct ldb_dn *dn = NULL;
 255
 256         werror = dns_name2dn(dns, mem_ctx, question->name, &dn);
 257         W_ERROR_NOT_OK_RETURN(werror);
 258
 259         werror = dns_lookup_records(dns, mem_ctx, dn, &recs, &rec_count);
 260         W_ERROR_NOT_OK_RETURN(werror);
 261
 262         ans = talloc_zero_array(mem_ctx, struct dns_res_rec, rec_count);
 263         W_ERROR_HAVE_NO_MEMORY(ans);
 264
 265         for (ri = 0; ri < rec_count; ri++) {
 266                 if ((question->question_type != DNS_QTYPE_ALL) &&
 267                     (recs[ri].wType != question->question_type)) {
 268                         continue;
 269                 }
 270                 werror = create_response_rr(question, &recs[ri], &ans, &ai);
 271                 W_ERROR_NOT_OK_RETURN(werror);
 272         }
 273
 274         if (ai == 0) {
 275                 return DNS_ERR(NAME_ERROR);
 276         }
 277
 278         *ancount = ai;
 279         *answers = ans;
 280
 281         return WERR_OK;
 282
 283 }
 284
 285 struct dns_server_process_query_state {
 286         struct dns_res_rec *answers;
 287         uint16_t ancount;
 288         struct dns_res_rec *nsrecs;
 289         uint16_t nscount;
 290         struct dns_res_rec *additional;
 291         uint16_t arcount;
 292 };
 293
 294 static void dns_server_process_query_got_response(struct tevent_req *subreq);
 295
 296 struct tevent_req *dns_server_process_query_send(
 297         TALLOC_CTX *mem_ctx, struct tevent_context *ev,
 298         struct dns_server *dns, struct dns_request_state *req_state,
 299         const struct dns_name_packet *in)
 300 {
 301         struct tevent_req *req, *subreq;
 302         struct dns_server_process_query_state *state;
 303
 304         req = tevent_req_create(mem_ctx, &state,
 305                                 struct dns_server_process_query_state);
 306         if (req == NULL) {
 307                 return NULL;
 308         }
 309         if (in->qdcount != 1) {
 310                 tevent_req_werror(req, DNS_ERR(FORMAT_ERROR));
 311                 return tevent_req_post(req, ev);
 312         }
 313
 314         /* Windows returns NOT_IMPLEMENTED on this as well */
 315         if (in->questions[0].question_class == DNS_QCLASS_NONE) {
 316                 tevent_req_werror(req, DNS_ERR(NOT_IMPLEMENTED));
 317                 return tevent_req_post(req, ev);
 318         }
 319
 320         if (dns_authorative_for_zone(dns, in->questions[0].name)) {
 321                 WERROR err;
 322
 323                 req_state->flags |= DNS_FLAG_AUTHORITATIVE;
 324                 err = handle_question(dns, state, &in->questions[0],
 325                                       &state->answers, &state->ancount);
 326                 if (tevent_req_werror(req, err)) {
 327                         return tevent_req_post(req, ev);
 328                 }
 329                 tevent_req_done(req);
 330                 return tevent_req_post(req, ev);
 331         }
 332
 333         if ((req_state->flags & DNS_FLAG_RECURSION_DESIRED) &&
 334             (req_state->flags & DNS_FLAG_RECURSION_AVAIL)) {
 335                 DEBUG(2, ("Not authoritative for '%s', forwarding\n",
 336                           in->questions[0].name));
 337
 338                 subreq = ask_forwarder_send(
 339                         state, ev, lpcfg_dns_forwarder(dns->task->lp_ctx),
 340                         &in->questions[0]);
 341                 if (tevent_req_nomem(subreq, req)) {
 342                         return tevent_req_post(req, ev);
 343                 }
 344                 tevent_req_set_callback(
 345                         subreq, dns_server_process_query_got_response, req);
 346                 return req;
 347         }
 348
 349         tevent_req_werror(req, DNS_ERR(NAME_ERROR));
 350         return tevent_req_post(req, ev);
 351 }
 352
 353 static void dns_server_process_query_got_response(struct tevent_req *subreq)
 354 {
 355         struct tevent_req *req = tevent_req_callback_data(
 356                 subreq, struct tevent_req);
 357         struct dns_server_process_query_state *state = tevent_req_data(
 358                 req, struct dns_server_process_query_state);
 359         WERROR err;
 360
 361         err = ask_forwarder_recv(subreq, state,
 362                                  &state->answers, &state->ancount,
 363                                  &state->nsrecs, &state->nscount,
 364                                  &state->additional, &state->arcount);
 365         TALLOC_FREE(subreq);
 366         if (tevent_req_werror(req, err)) {
 367                 return;
 368         }
 369         tevent_req_done(req);
 370 }
 371
 372 WERROR dns_server_process_query_recv(
 373         struct tevent_req *req, TALLOC_CTX *mem_ctx,
 374         struct dns_res_rec **answers,    uint16_t *ancount,
 375         struct dns_res_rec **nsrecs,     uint16_t *nscount,
 376         struct dns_res_rec **additional, uint16_t *arcount)
 377 {
 378         struct dns_server_process_query_state *state = tevent_req_data(
 379                 req, struct dns_server_process_query_state);
 380         WERROR err;
 381
 382         if (tevent_req_is_werror(req, &err)) {
 383                 return err;
 384         }
 385         *answers = talloc_move(mem_ctx, &state->answers);
 386         *ancount = state->ancount;
 387         *nsrecs = talloc_move(mem_ctx, &state->nsrecs);
 388         *nscount = state->nscount;
 389         *additional = talloc_move(mem_ctx, &state->additional);
 390         *arcount = state->arcount;
 391         return WERR_OK;
 392 }