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
  36 static WERROR create_response_rr(const struct dns_name_question *question,
  37                                  const struct dnsp_DnssrvRpcRecord *rec,
  38                                  struct dns_res_rec **answers, uint16_t *ancount)
  39 {
  40         struct dns_res_rec *ans = *answers;
  41         uint16_t ai = *ancount;
  42         char *tmp;
  43         uint32_t i;
  44
  45         ZERO_STRUCT(ans[ai]);
  46
  47         switch (rec->wType) {
  48         case DNS_QTYPE_CNAME:
  49                 ans[ai].rdata.cname_record = talloc_strdup(ans, rec->data.cname);
  50                 if (ans[ai].rdata.cname_record == NULL) {
  51                         return WERR_NOMEM;
  52                 }
  53                 break;
  54         case DNS_QTYPE_A:
  55                 ans[ai].rdata.ipv4_record = talloc_strdup(ans, rec->data.ipv4);
  56                 if (ans[ai].rdata.ipv4_record == NULL) {
  57                         return WERR_NOMEM;
  58                 }
  59                 break;
  60         case DNS_QTYPE_AAAA:
  61                 ans[ai].rdata.ipv6_record = rec->data.ipv6;
  62                 break;
  63         case DNS_TYPE_NS:
  64                 ans[ai].rdata.ns_record = rec->data.ns;
  65                 break;
  66         case DNS_QTYPE_SRV:
  67                 ans[ai].rdata.srv_record.priority = rec->data.srv.wPriority;
  68                 ans[ai].rdata.srv_record.weight   = rec->data.srv.wWeight;
  69                 ans[ai].rdata.srv_record.port     = rec->data.srv.wPort;
  70                 ans[ai].rdata.srv_record.target   = rec->data.srv.nameTarget;
  71                 break;
  72         case DNS_QTYPE_SOA:
  73                 ans[ai].rdata.soa_record.mname   = rec->data.soa.mname;
  74                 ans[ai].rdata.soa_record.rname   = rec->data.soa.rname;
  75                 ans[ai].rdata.soa_record.serial  = rec->data.soa.serial;
  76                 ans[ai].rdata.soa_record.refresh = rec->data.soa.refresh;
  77                 ans[ai].rdata.soa_record.retry   = rec->data.soa.retry;
  78                 ans[ai].rdata.soa_record.expire  = rec->data.soa.expire;
  79                 ans[ai].rdata.soa_record.minimum = rec->data.soa.minimum;
  80                 break;
  81         case DNS_QTYPE_PTR:
  82                 ans[ai].rdata.ptr_record = talloc_strdup(ans, rec->data.ptr);
  83                 break;
  84         case DNS_QTYPE_TXT:
  85                 tmp = talloc_asprintf(ans, "\"%s\"", rec->data.txt.str[0]);
  86                 if (tmp == NULL) {
  87                         return WERR_NOMEM;
  88                 }
  89                 for (i=1; i<rec->data.txt.count; i++) {
  90                         tmp = talloc_asprintf_append_buffer(
  91                                 tmp, " \"%s\"", rec->data.txt.str[i]);
  92                         if (tmp == NULL) {
  93                                 return WERR_NOMEM;
  94                         }
  95                 }
  96                 ans[ai].rdata.txt_record.txt = tmp;
  97                 break;
  98         default:
  99                 DEBUG(0, ("Got unhandled type %u query.\n", rec->wType));
 100                 return DNS_ERR(NOT_IMPLEMENTED);
 101         }
 102
 103         ans[ai].name = talloc_strdup(ans, question->name);
 104         if (ans[ai].name == NULL) {
 105                 return WERR_NOMEM;
 106         }
 107         ans[ai].rr_type = rec->wType;
 108         ans[ai].rr_class = DNS_QCLASS_IN;
 109         ans[ai].ttl = rec->dwTtlSeconds;
 110         ans[ai].length = UINT16_MAX;
 111         ai++;
 112
 113         *answers = ans;
 114         *ancount = ai;
 115
 116         return WERR_OK;
 117 }
 118
 119 static WERROR ask_forwarder(struct dns_server *dns,
 120                             TALLOC_CTX *mem_ctx,
 121                             struct dns_name_question *question,
 122                             struct dns_res_rec **answers, uint16_t *ancount,
 123                             struct dns_res_rec **nsrecs, uint16_t *nscount,
 124                             struct dns_res_rec **additional, uint16_t *arcount)
 125 {
 126         struct tevent_context *ev = tevent_context_init(mem_ctx);
 127         struct dns_name_packet *out_packet, *in_packet;
 128         uint16_t id = random();
 129         DATA_BLOB out, in;
 130         enum ndr_err_code ndr_err;
 131         WERROR werr = WERR_OK;
 132         struct tevent_req *req;
 133         const char *forwarder = lpcfg_dns_forwarder(dns->task->lp_ctx);
 134
 135         if (!is_ipaddress(forwarder)) {
 136                 DEBUG(0, ("Invalid 'dns forwarder' setting '%s', needs to be "
 137                           "an IP address\n", forwarder));
 138                 return DNS_ERR(NAME_ERROR);
 139         }
 140
 141         out_packet = talloc_zero(mem_ctx, struct dns_name_packet);
 142         W_ERROR_HAVE_NO_MEMORY(out_packet);
 143
 144         out_packet->id = id;
 145         out_packet->operation |= DNS_OPCODE_QUERY | DNS_FLAG_RECURSION_DESIRED;
 146
 147         out_packet->qdcount = 1;
 148         out_packet->questions = question;
 149
 150         ndr_err = ndr_push_struct_blob(&out, mem_ctx, out_packet,
 151                         (ndr_push_flags_fn_t)ndr_push_dns_name_packet);
 152         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 153                 return DNS_ERR(SERVER_FAILURE);
 154         }
 155
 156         req = dns_udp_request_send(mem_ctx, ev, forwarder, out.data, out.length);
 157         W_ERROR_HAVE_NO_MEMORY(req);
 158
 159         if(!tevent_req_poll(req, ev)) {
 160                 return DNS_ERR(SERVER_FAILURE);
 161         }
 162
 163         werr = dns_udp_request_recv(req, mem_ctx, &in.data, &in.length);
 164         W_ERROR_NOT_OK_RETURN(werr);
 165
 166         in_packet = talloc_zero(mem_ctx, struct dns_name_packet);
 167         W_ERROR_HAVE_NO_MEMORY(in_packet);
 168
 169         ndr_err = ndr_pull_struct_blob(&in, in_packet, in_packet,
 170                         (ndr_pull_flags_fn_t)ndr_pull_dns_name_packet);
 171         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 172                 return DNS_ERR(SERVER_FAILURE);
 173         }
 174
 175         if (in_packet->id != id) {
 176                 DEBUG(0, ("DNS packet id mismatch: 0x%0x, expected 0x%0x\n",
 177                           in_packet->id, id));
 178                 return DNS_ERR(NAME_ERROR);
 179         }
 180
 181         *ancount = in_packet->ancount;
 182         *answers = talloc_move(mem_ctx, &in_packet->answers);
 183
 184         *nscount = in_packet->nscount;
 185         *nsrecs = talloc_move(mem_ctx, &in_packet->nsrecs);
 186
 187         *arcount = in_packet->arcount;
 188         *additional = talloc_move(mem_ctx, &in_packet->additional);
 189
 190         return werr;
 191 }
 192
 193 static WERROR handle_question(struct dns_server *dns,
 194                               TALLOC_CTX *mem_ctx,
 195                               const struct dns_name_question *question,
 196                               struct dns_res_rec **answers, uint16_t *ancount)
 197 {
 198         struct dns_res_rec *ans;
 199         WERROR werror;
 200         unsigned int ri;
 201         struct dnsp_DnssrvRpcRecord *recs;
 202         uint16_t rec_count, ai = 0;
 203         struct ldb_dn *dn = NULL;
 204
 205         werror = dns_name2dn(dns, mem_ctx, question->name, &dn);
 206         W_ERROR_NOT_OK_RETURN(werror);
 207
 208         werror = dns_lookup_records(dns, mem_ctx, dn, &recs, &rec_count);
 209         W_ERROR_NOT_OK_RETURN(werror);
 210
 211         ans = talloc_zero_array(mem_ctx, struct dns_res_rec, rec_count);
 212         W_ERROR_HAVE_NO_MEMORY(ans);
 213
 214         for (ri = 0; ri < rec_count; ri++) {
 215                 if ((question->question_type != DNS_QTYPE_ALL) &&
 216                     (recs[ri].wType != question->question_type)) {
 217                         continue;
 218                 }
 219                 werror = create_response_rr(question, &recs[ri], &ans, &ai);
 220                 W_ERROR_NOT_OK_RETURN(werror);
 221         }
 222
 223         if (ai == 0) {
 224                 return DNS_ERR(NAME_ERROR);
 225         }
 226
 227         *ancount = ai;
 228         *answers = ans;
 229
 230         return WERR_OK;
 231
 232 }
 233
 234 WERROR dns_server_process_query(struct dns_server *dns,
 235                                 struct dns_request_state *state,
 236                                 TALLOC_CTX *mem_ctx,
 237                                 struct dns_name_packet *in,
 238                                 struct dns_res_rec **answers,    uint16_t *ancount,
 239                                 struct dns_res_rec **nsrecs,     uint16_t *nscount,
 240                                 struct dns_res_rec **additional, uint16_t *arcount)
 241 {
 242         uint16_t num_answers=0, num_nsrecs=0, num_additional=0;
 243         struct dns_res_rec *ans=NULL, *ns=NULL, *adds=NULL;
 244         WERROR werror;
 245
 246         if (in->qdcount != 1) {
 247                 return DNS_ERR(FORMAT_ERROR);
 248         }
 249
 250         /* Windows returns NOT_IMPLEMENTED on this as well */
 251         if (in->questions[0].question_class == DNS_QCLASS_NONE) {
 252                 return DNS_ERR(NOT_IMPLEMENTED);
 253         }
 254
 255         if (dns_authorative_for_zone(dns, in->questions[0].name)) {
 256                 state->flags |= DNS_FLAG_AUTHORITATIVE;
 257                 werror = handle_question(dns, mem_ctx, &in->questions[0],
 258                                          &ans, &num_answers);
 259         } else {
 260                 if (state->flags & DNS_FLAG_RECURSION_DESIRED &&
 261                     state->flags & DNS_FLAG_RECURSION_AVAIL) {
 262                         DEBUG(2, ("Not authorative for '%s', forwarding\n",
 263                                   in->questions[0].name));
 264                         werror = ask_forwarder(dns, mem_ctx, &in->questions[0],
 265                                                &ans, &num_answers,
 266                                                &ns, &num_nsrecs,
 267                                                &adds, &num_additional);
 268                 } else {
 269                         werror = DNS_ERR(NAME_ERROR);
 270                 }
 271         }
 272         W_ERROR_NOT_OK_GOTO(werror, query_failed);
 273
 274         *answers = ans;
 275         *ancount = num_answers;
 276
 277         /*FIXME: Do something for these */
 278         *nsrecs  = ns;
 279         *nscount = num_nsrecs;
 280
 281         *additional = adds;
 282         *arcount    = num_additional;
 283
 284         return WERR_OK;
 285
 286 query_failed:
 287         /*FIXME: add our SOA record to nsrecs */
 288         return werror;
 289 }