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