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 = talloc_strdup(ans, rec->data.ns);
  67                 W_ERROR_HAVE_NO_MEMORY(ans[ai].rdata.ns_record);
  68                 break;
  69         case DNS_QTYPE_SRV:
  70                 ans[ai].rdata.srv_record.priority = rec->data.srv.wPriority;
  71                 ans[ai].rdata.srv_record.weight   = rec->data.srv.wWeight;
  72                 ans[ai].rdata.srv_record.port     = rec->data.srv.wPort;
  73                 ans[ai].rdata.srv_record.target   = talloc_strdup(
  74                         ans, rec->data.srv.nameTarget);
  75                 if (ans[ai].rdata.srv_record.target == NULL) {
  76                         return WERR_NOMEM;
  77                 }
  78                 break;
  79         case DNS_QTYPE_SOA:
  80                 ans[ai].rdata.soa_record.mname   = talloc_strdup(
  81                         ans, rec->data.soa.mname);
  82                 if (ans[ai].rdata.soa_record.mname == NULL) {
  83                         return WERR_NOMEM;
  84                 }
  85                 ans[ai].rdata.soa_record.rname   = talloc_strdup(
  86                         ans, rec->data.soa.rname);
  87                 if (ans[ai].rdata.soa_record.rname == NULL) {
  88                         return WERR_NOMEM;
  89                 }
  90                 ans[ai].rdata.soa_record.serial  = rec->data.soa.serial;
  91                 ans[ai].rdata.soa_record.refresh = rec->data.soa.refresh;
  92                 ans[ai].rdata.soa_record.retry   = rec->data.soa.retry;
  93                 ans[ai].rdata.soa_record.expire  = rec->data.soa.expire;
  94                 ans[ai].rdata.soa_record.minimum = rec->data.soa.minimum;
  95                 break;
  96         case DNS_QTYPE_PTR:
  97                 ans[ai].rdata.ptr_record = talloc_strdup(ans, rec->data.ptr);
  98                 break;
  99         case DNS_QTYPE_TXT:
 100                 tmp = talloc_asprintf(ans, "\"%s\"", rec->data.txt.str[0]);
 101                 if (tmp == NULL) {
 102                         return WERR_NOMEM;
 103                 }
 104                 for (i=1; i<rec->data.txt.count; i++) {
 105                         tmp = talloc_asprintf_append_buffer(
 106                                 tmp, " \"%s\"", rec->data.txt.str[i]);
 107                         if (tmp == NULL) {
 108                                 return WERR_NOMEM;
 109                         }
 110                 }
 111                 ans[ai].rdata.txt_record.txt = tmp;
 112                 break;
 113         default:
 114                 DEBUG(0, ("Got unhandled type %u query.\n", rec->wType));
 115                 return DNS_ERR(NOT_IMPLEMENTED);
 116         }
 117
 118         ans[ai].name = talloc_strdup(ans, question->name);
 119         if (ans[ai].name == NULL) {
 120                 return WERR_NOMEM;
 121         }
 122         ans[ai].rr_type = rec->wType;
 123         ans[ai].rr_class = DNS_QCLASS_IN;
 124         ans[ai].ttl = rec->dwTtlSeconds;
 125         ans[ai].length = UINT16_MAX;
 126         ai++;
 127
 128         *answers = ans;
 129         *ancount = ai;
 130
 131         return WERR_OK;
 132 }
 133
 134 struct ask_forwarder_state {
 135         struct tevent_context *ev;
 136         uint16_t id;
 137         struct dns_name_packet in_packet;
 138 };
 139
 140 static void ask_forwarder_done(struct tevent_req *subreq);
 141
 142 static struct tevent_req *ask_forwarder_send(
 143         TALLOC_CTX *mem_ctx, struct tevent_context *ev,
 144         const char *forwarder, struct dns_name_question *question)
 145 {
 146         struct tevent_req *req, *subreq;
 147         struct ask_forwarder_state *state;
 148         struct dns_name_packet out_packet = { 0, };
 149         DATA_BLOB out_blob;
 150         enum ndr_err_code ndr_err;
 151
 152         req = tevent_req_create(mem_ctx, &state, struct ask_forwarder_state);
 153         if (req == NULL) {
 154                 return NULL;
 155         }
 156         state->ev = ev;
 157         generate_random_buffer((uint8_t *)&state->id, sizeof(state->id));
 158
 159         if (!is_ipaddress(forwarder)) {
 160                 DEBUG(0, ("Invalid 'dns forwarder' setting '%s', needs to be "
 161                           "an IP address\n", forwarder));
 162                 tevent_req_werror(req, DNS_ERR(NAME_ERROR));
 163                 return tevent_req_post(req, ev);
 164         }
 165
 166         out_packet.id = state->id;
 167         out_packet.operation |= DNS_OPCODE_QUERY | DNS_FLAG_RECURSION_DESIRED;
 168         out_packet.qdcount = 1;
 169         out_packet.questions = question;
 170
 171         ndr_err = ndr_push_struct_blob(
 172                 &out_blob, state, &out_packet,
 173                 (ndr_push_flags_fn_t)ndr_push_dns_name_packet);
 174         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 175                 tevent_req_werror(req, DNS_ERR(SERVER_FAILURE));
 176                 return tevent_req_post(req, ev);
 177         }
 178         subreq = dns_udp_request_send(state, ev, forwarder, out_blob.data,
 179                                       out_blob.length);
 180         if (tevent_req_nomem(subreq, req)) {
 181                 return tevent_req_post(req, ev);
 182         }
 183         tevent_req_set_callback(subreq, ask_forwarder_done, req);
 184         return req;
 185 }
 186
 187 static void ask_forwarder_done(struct tevent_req *subreq)
 188 {
 189         struct tevent_req *req = tevent_req_callback_data(
 190                 subreq, struct tevent_req);
 191         struct ask_forwarder_state *state = tevent_req_data(
 192                 req, struct ask_forwarder_state);
 193         DATA_BLOB in_blob;
 194         enum ndr_err_code ndr_err;
 195         WERROR ret;
 196
 197         ret = dns_udp_request_recv(subreq, state,
 198                                    &in_blob.data, &in_blob.length);
 199         TALLOC_FREE(subreq);
 200         if (tevent_req_werror(req, ret)) {
 201                 return;
 202         }
 203
 204         ndr_err = ndr_pull_struct_blob(
 205                 &in_blob, state, &state->in_packet,
 206                 (ndr_pull_flags_fn_t)ndr_pull_dns_name_packet);
 207         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 208                 tevent_req_werror(req, DNS_ERR(SERVER_FAILURE));
 209                 return;
 210         }
 211         if (state->in_packet.id != state->id) {
 212                 tevent_req_werror(req, DNS_ERR(NAME_ERROR));
 213                 return;
 214         }
 215         tevent_req_done(req);
 216 }
 217
 218 static WERROR ask_forwarder_recv(
 219         struct tevent_req *req, TALLOC_CTX *mem_ctx,
 220         struct dns_res_rec **answers, uint16_t *ancount,
 221         struct dns_res_rec **nsrecs, uint16_t *nscount,
 222         struct dns_res_rec **additional, uint16_t *arcount)
 223 {
 224         struct ask_forwarder_state *state = tevent_req_data(
 225                 req, struct ask_forwarder_state);
 226         struct dns_name_packet *in_packet = &state->in_packet;
 227         WERROR err;
 228
 229         if (tevent_req_is_werror(req, &err)) {
 230                 return err;
 231         }
 232
 233         *ancount = in_packet->ancount;
 234         *answers = talloc_move(mem_ctx, &in_packet->answers);
 235
 236         *nscount = in_packet->nscount;
 237         *nsrecs = talloc_move(mem_ctx, &in_packet->nsrecs);
 238
 239         *arcount = in_packet->arcount;
 240         *additional = talloc_move(mem_ctx, &in_packet->additional);
 241
 242         return WERR_OK;
 243 }
 244
 245 static WERROR handle_question(struct dns_server *dns,
 246                               TALLOC_CTX *mem_ctx,
 247                               const struct dns_name_question *question,
 248                               struct dns_res_rec **answers, uint16_t *ancount)
 249 {
 250         struct dns_res_rec *ans;
 251         WERROR werror;
 252         unsigned int ri;
 253         struct dnsp_DnssrvRpcRecord *recs;
 254         uint16_t rec_count, ai = 0;
 255         struct ldb_dn *dn = NULL;
 256
 257         werror = dns_name2dn(dns, mem_ctx, question->name, &dn);
 258         W_ERROR_NOT_OK_RETURN(werror);
 259
 260         werror = dns_lookup_records(dns, mem_ctx, dn, &recs, &rec_count);
 261         W_ERROR_NOT_OK_RETURN(werror);
 262
 263         ans = talloc_zero_array(mem_ctx, struct dns_res_rec, rec_count);
 264         W_ERROR_HAVE_NO_MEMORY(ans);
 265
 266         for (ri = 0; ri < rec_count; ri++) {
 267                 if ((question->question_type != DNS_QTYPE_ALL) &&
 268                     (recs[ri].wType != question->question_type)) {
 269                         continue;
 270                 }
 271                 werror = create_response_rr(question, &recs[ri], &ans, &ai);
 272                 W_ERROR_NOT_OK_RETURN(werror);
 273         }
 274
 275         if (ai == 0) {
 276                 return DNS_ERR(NAME_ERROR);
 277         }
 278
 279         *ancount = ai;
 280         *answers = ans;
 281
 282         return WERR_OK;
 283
 284 }
 285
 286 struct dns_server_process_query_state {
 287         struct dns_res_rec *answers;
 288         uint16_t ancount;
 289         struct dns_res_rec *nsrecs;
 290         uint16_t nscount;
 291         struct dns_res_rec *additional;
 292         uint16_t arcount;
 293 };
 294
 295 static void dns_server_process_query_got_response(struct tevent_req *subreq);
 296
 297 struct tevent_req *dns_server_process_query_send(
 298         TALLOC_CTX *mem_ctx, struct tevent_context *ev,
 299         struct dns_server *dns, struct dns_request_state *req_state,
 300         const struct dns_name_packet *in)
 301 {
 302         struct tevent_req *req, *subreq;
 303         struct dns_server_process_query_state *state;
 304
 305         req = tevent_req_create(mem_ctx, &state,
 306                                 struct dns_server_process_query_state);
 307         if (req == NULL) {
 308                 return NULL;
 309         }
 310         if (in->qdcount != 1) {
 311                 tevent_req_werror(req, DNS_ERR(FORMAT_ERROR));
 312                 return tevent_req_post(req, ev);
 313         }
 314
 315         /* Windows returns NOT_IMPLEMENTED on this as well */
 316         if (in->questions[0].question_class == DNS_QCLASS_NONE) {
 317                 tevent_req_werror(req, DNS_ERR(NOT_IMPLEMENTED));
 318                 return tevent_req_post(req, ev);
 319         }
 320
 321         if (dns_authorative_for_zone(dns, in->questions[0].name)) {
 322                 WERROR err;
 323
 324                 req_state->flags |= DNS_FLAG_AUTHORITATIVE;
 325                 err = handle_question(dns, state, &in->questions[0],
 326                                       &state->answers, &state->ancount);
 327                 if (tevent_req_werror(req, err)) {
 328                         return tevent_req_post(req, ev);
 329                 }
 330                 tevent_req_done(req);
 331                 return tevent_req_post(req, ev);
 332         }
 333
 334         if ((req_state->flags & DNS_FLAG_RECURSION_DESIRED) &&
 335             (req_state->flags & DNS_FLAG_RECURSION_AVAIL)) {
 336                 DEBUG(2, ("Not authoritative for '%s', forwarding\n",
 337                           in->questions[0].name));
 338
 339                 subreq = ask_forwarder_send(
 340                         state, ev, lpcfg_dns_forwarder(dns->task->lp_ctx),
 341                         &in->questions[0]);
 342                 if (tevent_req_nomem(subreq, req)) {
 343                         return tevent_req_post(req, ev);
 344                 }
 345                 tevent_req_set_callback(
 346                         subreq, dns_server_process_query_got_response, req);
 347                 return req;
 348         }
 349
 350         tevent_req_werror(req, DNS_ERR(NAME_ERROR));
 351         return tevent_req_post(req, ev);
 352 }
 353
 354 static void dns_server_process_query_got_response(struct tevent_req *subreq)
 355 {
 356         struct tevent_req *req = tevent_req_callback_data(
 357                 subreq, struct tevent_req);
 358         struct dns_server_process_query_state *state = tevent_req_data(
 359                 req, struct dns_server_process_query_state);
 360         WERROR err;
 361
 362         err = ask_forwarder_recv(subreq, state,
 363                                  &state->answers, &state->ancount,
 364                                  &state->nsrecs, &state->nscount,
 365                                  &state->additional, &state->arcount);
 366         TALLOC_FREE(subreq);
 367         if (tevent_req_werror(req, err)) {
 368                 return;
 369         }
 370         tevent_req_done(req);
 371 }
 372
 373 WERROR dns_server_process_query_recv(
 374         struct tevent_req *req, TALLOC_CTX *mem_ctx,
 375         struct dns_res_rec **answers,    uint16_t *ancount,
 376         struct dns_res_rec **nsrecs,     uint16_t *nscount,
 377         struct dns_res_rec **additional, uint16_t *arcount)
 378 {
 379         struct dns_server_process_query_state *state = tevent_req_data(
 380                 req, struct dns_server_process_query_state);
 381         WERROR err;
 382
 383         if (tevent_req_is_werror(req, &err)) {
 384                 return err;
 385         }
 386         *answers = talloc_move(mem_ctx, &state->answers);
 387         *ancount = state->ancount;
 388         *nsrecs = talloc_move(mem_ctx, &state->nsrecs);
 389         *nscount = state->nscount;
 390         *additional = talloc_move(mem_ctx, &state->additional);
 391         *arcount = state->arcount;
 392         return WERR_OK;
 393 }