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