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   = talloc_strdup(
  71                         ans, rec->data.srv.nameTarget);
  72                 if (ans[ai].rdata.srv_record.target == NULL) {
  73                         return WERR_NOMEM;
  74                 }
  75                 break;
  76         case DNS_QTYPE_SOA:
  77                 ans[ai].rdata.soa_record.mname   = talloc_strdup(
  78                         ans, rec->data.soa.mname);
  79                 if (ans[ai].rdata.soa_record.mname == NULL) {
  80                         return WERR_NOMEM;
  81                 }
  82                 ans[ai].rdata.soa_record.rname   = talloc_strdup(
  83                         ans, rec->data.soa.rname);
  84                 if (ans[ai].rdata.soa_record.rname == NULL) {
  85                         return WERR_NOMEM;
  86                 }
  87                 ans[ai].rdata.soa_record.serial  = rec->data.soa.serial;
  88                 ans[ai].rdata.soa_record.refresh = rec->data.soa.refresh;
  89                 ans[ai].rdata.soa_record.retry   = rec->data.soa.retry;
  90                 ans[ai].rdata.soa_record.expire  = rec->data.soa.expire;
  91                 ans[ai].rdata.soa_record.minimum = rec->data.soa.minimum;
  92                 break;
  93         case DNS_QTYPE_PTR:
  94                 ans[ai].rdata.ptr_record = talloc_strdup(ans, rec->data.ptr);
  95                 break;
  96         case DNS_QTYPE_TXT:
  97                 tmp = talloc_asprintf(ans, "\"%s\"", rec->data.txt.str[0]);
  98                 if (tmp == NULL) {
  99                         return WERR_NOMEM;
 100                 }
 101                 for (i=1; i<rec->data.txt.count; i++) {
 102                         tmp = talloc_asprintf_append_buffer(
 103                                 tmp, " \"%s\"", rec->data.txt.str[i]);
 104                         if (tmp == NULL) {
 105                                 return WERR_NOMEM;
 106                         }
 107                 }
 108                 ans[ai].rdata.txt_record.txt = tmp;
 109                 break;
 110         default:
 111                 DEBUG(0, ("Got unhandled type %u query.\n", rec->wType));
 112                 return DNS_ERR(NOT_IMPLEMENTED);
 113         }
 114
 115         ans[ai].name = talloc_strdup(ans, question->name);
 116         if (ans[ai].name == NULL) {
 117                 return WERR_NOMEM;
 118         }
 119         ans[ai].rr_type = rec->wType;
 120         ans[ai].rr_class = DNS_QCLASS_IN;
 121         ans[ai].ttl = rec->dwTtlSeconds;
 122         ans[ai].length = UINT16_MAX;
 123         ai++;
 124
 125         *answers = ans;
 126         *ancount = ai;
 127
 128         return WERR_OK;
 129 }
 130
 131 static WERROR ask_forwarder(struct dns_server *dns,
 132                             TALLOC_CTX *mem_ctx,
 133                             struct dns_name_question *question,
 134                             struct dns_res_rec **answers, uint16_t *ancount,
 135                             struct dns_res_rec **nsrecs, uint16_t *nscount,
 136                             struct dns_res_rec **additional, uint16_t *arcount)
 137 {
 138         struct tevent_context *ev = tevent_context_init(mem_ctx);
 139         struct dns_name_packet *out_packet, *in_packet;
 140         uint16_t id = random();
 141         DATA_BLOB out, in;
 142         enum ndr_err_code ndr_err;
 143         WERROR werr = WERR_OK;
 144         struct tevent_req *req;
 145         const char *forwarder = lpcfg_dns_forwarder(dns->task->lp_ctx);
 146
 147         if (!is_ipaddress(forwarder)) {
 148                 DEBUG(0, ("Invalid 'dns forwarder' setting '%s', needs to be "
 149                           "an IP address\n", forwarder));
 150                 return DNS_ERR(NAME_ERROR);
 151         }
 152
 153         out_packet = talloc_zero(mem_ctx, struct dns_name_packet);
 154         W_ERROR_HAVE_NO_MEMORY(out_packet);
 155
 156         out_packet->id = id;
 157         out_packet->operation |= DNS_OPCODE_QUERY | DNS_FLAG_RECURSION_DESIRED;
 158
 159         out_packet->qdcount = 1;
 160         out_packet->questions = question;
 161
 162         ndr_err = ndr_push_struct_blob(&out, mem_ctx, out_packet,
 163                         (ndr_push_flags_fn_t)ndr_push_dns_name_packet);
 164         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 165                 return DNS_ERR(SERVER_FAILURE);
 166         }
 167
 168         req = dns_udp_request_send(mem_ctx, ev, forwarder, out.data, out.length);
 169         W_ERROR_HAVE_NO_MEMORY(req);
 170
 171         if(!tevent_req_poll(req, ev)) {
 172                 return DNS_ERR(SERVER_FAILURE);
 173         }
 174
 175         werr = dns_udp_request_recv(req, mem_ctx, &in.data, &in.length);
 176         W_ERROR_NOT_OK_RETURN(werr);
 177
 178         in_packet = talloc_zero(mem_ctx, struct dns_name_packet);
 179         W_ERROR_HAVE_NO_MEMORY(in_packet);
 180
 181         ndr_err = ndr_pull_struct_blob(&in, in_packet, in_packet,
 182                         (ndr_pull_flags_fn_t)ndr_pull_dns_name_packet);
 183         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 184                 return DNS_ERR(SERVER_FAILURE);
 185         }
 186
 187         if (in_packet->id != id) {
 188                 DEBUG(0, ("DNS packet id mismatch: 0x%0x, expected 0x%0x\n",
 189                           in_packet->id, id));
 190                 return DNS_ERR(NAME_ERROR);
 191         }
 192
 193         *ancount = in_packet->ancount;
 194         *answers = talloc_move(mem_ctx, &in_packet->answers);
 195
 196         *nscount = in_packet->nscount;
 197         *nsrecs = talloc_move(mem_ctx, &in_packet->nsrecs);
 198
 199         *arcount = in_packet->arcount;
 200         *additional = talloc_move(mem_ctx, &in_packet->additional);
 201
 202         return werr;
 203 }
 204
 205 static WERROR handle_question(struct dns_server *dns,
 206                               TALLOC_CTX *mem_ctx,
 207                               const struct dns_name_question *question,
 208                               struct dns_res_rec **answers, uint16_t *ancount)
 209 {
 210         struct dns_res_rec *ans;
 211         WERROR werror;
 212         unsigned int ri;
 213         struct dnsp_DnssrvRpcRecord *recs;
 214         uint16_t rec_count, ai = 0;
 215         struct ldb_dn *dn = NULL;
 216
 217         werror = dns_name2dn(dns, mem_ctx, question->name, &dn);
 218         W_ERROR_NOT_OK_RETURN(werror);
 219
 220         werror = dns_lookup_records(dns, mem_ctx, dn, &recs, &rec_count);
 221         W_ERROR_NOT_OK_RETURN(werror);
 222
 223         ans = talloc_zero_array(mem_ctx, struct dns_res_rec, rec_count);
 224         W_ERROR_HAVE_NO_MEMORY(ans);
 225
 226         for (ri = 0; ri < rec_count; ri++) {
 227                 if ((question->question_type != DNS_QTYPE_ALL) &&
 228                     (recs[ri].wType != question->question_type)) {
 229                         continue;
 230                 }
 231                 werror = create_response_rr(question, &recs[ri], &ans, &ai);
 232                 W_ERROR_NOT_OK_RETURN(werror);
 233         }
 234
 235         if (ai == 0) {
 236                 return DNS_ERR(NAME_ERROR);
 237         }
 238
 239         *ancount = ai;
 240         *answers = ans;
 241
 242         return WERR_OK;
 243
 244 }
 245
 246 WERROR dns_server_process_query(struct dns_server *dns,
 247                                 struct dns_request_state *state,
 248                                 TALLOC_CTX *mem_ctx,
 249                                 struct dns_name_packet *in,
 250                                 struct dns_res_rec **answers,    uint16_t *ancount,
 251                                 struct dns_res_rec **nsrecs,     uint16_t *nscount,
 252                                 struct dns_res_rec **additional, uint16_t *arcount)
 253 {
 254         uint16_t num_answers=0, num_nsrecs=0, num_additional=0;
 255         struct dns_res_rec *ans=NULL, *ns=NULL, *adds=NULL;
 256         WERROR werror;
 257
 258         if (in->qdcount != 1) {
 259                 return DNS_ERR(FORMAT_ERROR);
 260         }
 261
 262         /* Windows returns NOT_IMPLEMENTED on this as well */
 263         if (in->questions[0].question_class == DNS_QCLASS_NONE) {
 264                 return DNS_ERR(NOT_IMPLEMENTED);
 265         }
 266
 267         if (dns_authorative_for_zone(dns, in->questions[0].name)) {
 268                 state->flags |= DNS_FLAG_AUTHORITATIVE;
 269                 werror = handle_question(dns, mem_ctx, &in->questions[0],
 270                                          &ans, &num_answers);
 271         } else {
 272                 if (state->flags & DNS_FLAG_RECURSION_DESIRED &&
 273                     state->flags & DNS_FLAG_RECURSION_AVAIL) {
 274                         DEBUG(2, ("Not authoritative for '%s', forwarding\n",
 275                                   in->questions[0].name));
 276                         werror = ask_forwarder(dns, mem_ctx, &in->questions[0],
 277                                                &ans, &num_answers,
 278                                                &ns, &num_nsrecs,
 279                                                &adds, &num_additional);
 280                 } else {
 281                         werror = DNS_ERR(NAME_ERROR);
 282                 }
 283         }
 284         W_ERROR_NOT_OK_GOTO(werror, query_failed);
 285
 286         *answers = ans;
 287         *ancount = num_answers;
 288
 289         /*FIXME: Do something for these */
 290         *nsrecs  = ns;
 291         *nscount = num_nsrecs;
 292
 293         *additional = adds;
 294         *arcount    = num_additional;
 295
 296         return WERR_OK;
 297
 298 query_failed:
 299         /*FIXME: add our SOA record to nsrecs */
 300         return werror;
 301 }