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 "libcli/util/werror.h"
  24 #include "librpc/ndr/libndr.h"
  25 #include "librpc/gen_ndr/ndr_dns.h"
  26 #include "librpc/gen_ndr/ndr_dnsp.h"
  27 #include <ldb.h>
  28 #include "dsdb/samdb/samdb.h"
  29 #include "dsdb/common/util.h"
  30 #include "dns_server/dns_server.h"
  31 #include "libcli/dns/libdns.h"
  32
  33 static WERROR create_response_rr(const struct dns_name_question *question,
  34                                  const struct dnsp_DnssrvRpcRecord *rec,
  35                                  struct dns_res_rec **answers, uint16_t *ancount)
  36 {
  37         struct dns_res_rec *ans = *answers;
  38         uint16_t ai = *ancount;
  39         char *tmp;
  40         uint32_t i;
  41
  42         ZERO_STRUCT(ans[ai]);
  43
  44         switch (rec->wType) {
  45         case DNS_QTYPE_CNAME:
  46                 ans[ai].rdata.cname_record = talloc_strdup(ans, rec->data.cname);
  47                 break;
  48         case DNS_QTYPE_A:
  49                 ans[ai].rdata.ipv4_record = talloc_strdup(ans, rec->data.ipv4);
  50                 break;
  51         case DNS_QTYPE_AAAA:
  52                 ans[ai].rdata.ipv6_record = rec->data.ipv6;
  53                 break;
  54         case DNS_TYPE_NS:
  55                 ans[ai].rdata.ns_record = rec->data.ns;
  56                 break;
  57         case DNS_QTYPE_SRV:
  58                 ans[ai].rdata.srv_record.priority = rec->data.srv.wPriority;
  59                 ans[ai].rdata.srv_record.weight   = rec->data.srv.wWeight;
  60                 ans[ai].rdata.srv_record.port     = rec->data.srv.wPort;
  61                 ans[ai].rdata.srv_record.target   = rec->data.srv.nameTarget;
  62                 break;
  63         case DNS_QTYPE_SOA:
  64                 ans[ai].rdata.soa_record.mname   = rec->data.soa.mname;
  65                 ans[ai].rdata.soa_record.rname   = rec->data.soa.rname;
  66                 ans[ai].rdata.soa_record.serial  = rec->data.soa.serial;
  67                 ans[ai].rdata.soa_record.refresh = rec->data.soa.refresh;
  68                 ans[ai].rdata.soa_record.retry   = rec->data.soa.retry;
  69                 ans[ai].rdata.soa_record.expire  = rec->data.soa.expire;
  70                 ans[ai].rdata.soa_record.minimum = rec->data.soa.minimum;
  71                 break;
  72         case DNS_QTYPE_PTR:
  73                 ans[ai].rdata.ptr_record = talloc_strdup(ans, rec->data.ptr);
  74                 break;
  75         case DNS_QTYPE_TXT:
  76                 tmp = talloc_asprintf(ans, "\"%s\"", rec->data.txt.str[0]);
  77                 for (i=1; i<rec->data.txt.count; i++) {
  78                         tmp = talloc_asprintf_append(tmp, " \"%s\"",
  79                                                      rec->data.txt.str[i]);
  80                 }
  81                 ans[ai].rdata.txt_record.txt = tmp;
  82                 break;
  83         default:
  84                 DEBUG(0, ("Got unhandled type %u query.\n", rec->wType));
  85                 return DNS_ERR(NOT_IMPLEMENTED);
  86         }
  87
  88         ans[ai].name = talloc_strdup(ans, question->name);
  89         ans[ai].rr_type = rec->wType;
  90         ans[ai].rr_class = DNS_QCLASS_IN;
  91         ans[ai].ttl = rec->dwTtlSeconds;
  92         ans[ai].length = UINT16_MAX;
  93         ai++;
  94
  95         *answers = ans;
  96         *ancount = ai;
  97
  98         return WERR_OK;
  99 }
 100
 101 static WERROR ask_forwarder(TALLOC_CTX *mem_ctx,
 102                             struct dns_name_question *question,
 103                             struct dns_res_rec **answers, uint16_t *ancount,
 104                             struct dns_res_rec **nsrecs, uint16_t *nscount,
 105                             struct dns_res_rec **additional, uint16_t *arcount)
 106 {
 107         struct tevent_context *ev = tevent_context_init(mem_ctx);
 108         struct dns_name_packet *out_packet, *in_packet;
 109         uint16_t id = random();
 110         DATA_BLOB out, in;
 111         enum ndr_err_code ndr_err;
 112         WERROR werr = WERR_OK;
 113         struct tevent_req *req;
 114
 115         out_packet = talloc_zero(mem_ctx, struct dns_name_packet);
 116         W_ERROR_HAVE_NO_MEMORY(out_packet);
 117
 118         out_packet->id = id;
 119         out_packet->operation |= DNS_OPCODE_QUERY | DNS_FLAG_RECURSION_DESIRED;
 120
 121         out_packet->qdcount = 1;
 122         out_packet->questions = question;
 123
 124         ndr_err = ndr_push_struct_blob(&out, mem_ctx, out_packet,
 125                         (ndr_push_flags_fn_t)ndr_push_dns_name_packet);
 126         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 127                 return DNS_ERR(SERVER_FAILURE);
 128         }
 129
 130         /* FIXME: Don't hardcode this, get that from a configuration somewhere */
 131         req = dns_udp_request_send(mem_ctx, ev, "127.0.0.1", out.data, out.length);
 132         W_ERROR_HAVE_NO_MEMORY(req);
 133
 134         if(!tevent_req_poll(req, ev)) {
 135                 return DNS_ERR(SERVER_FAILURE);
 136         }
 137
 138         werr = dns_udp_request_recv(req, mem_ctx, &in.data, &in.length);
 139         W_ERROR_NOT_OK_RETURN(werr);
 140
 141         in_packet = talloc_zero(mem_ctx, struct dns_name_packet);
 142         W_ERROR_HAVE_NO_MEMORY(in_packet);
 143
 144         ndr_err = ndr_pull_struct_blob(&in, in_packet, in_packet,
 145                         (ndr_pull_flags_fn_t)ndr_pull_dns_name_packet);
 146         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 147                 return DNS_ERR(SERVER_FAILURE);
 148         }
 149
 150         if (in_packet->id != id) {
 151                 DEBUG(0, ("DNS packet id mismatch: 0x%0x, expected 0x%0x\n",
 152                           in_packet->id, id));
 153                 return DNS_ERR(NAME_ERROR);
 154         }
 155
 156         *ancount = in_packet->ancount;
 157         *answers = talloc_move(mem_ctx, &in_packet->answers);
 158
 159         *nscount = in_packet->nscount;
 160         *nsrecs = talloc_move(mem_ctx, &in_packet->nsrecs);
 161
 162         *arcount = in_packet->arcount;
 163         *additional = talloc_move(mem_ctx, &in_packet->additional);
 164
 165         return werr;
 166 }
 167
 168 static WERROR handle_question(struct dns_server *dns,
 169                               TALLOC_CTX *mem_ctx,
 170                               const struct dns_name_question *question,
 171                               struct dns_res_rec **answers, uint16_t *ancount)
 172 {
 173         struct dns_res_rec *ans;
 174         WERROR werror;
 175         unsigned int ri;
 176         struct dnsp_DnssrvRpcRecord *recs;
 177         uint16_t rec_count, ai = 0;
 178         struct ldb_dn *dn = NULL;
 179
 180         werror = dns_name2dn(dns, mem_ctx, question->name, &dn);
 181         W_ERROR_NOT_OK_RETURN(werror);
 182
 183         werror = dns_lookup_records(dns, mem_ctx, dn, &recs, &rec_count);
 184         W_ERROR_NOT_OK_RETURN(werror);
 185
 186         ans = talloc_zero_array(mem_ctx, struct dns_res_rec, rec_count);
 187         W_ERROR_HAVE_NO_MEMORY(ans);
 188
 189         for (ri = 0; ri < rec_count; ri++) {
 190                 if ((question->question_type != DNS_QTYPE_ALL) &&
 191                     (recs[ri].wType != question->question_type)) {
 192                         continue;
 193                 }
 194                 werror = create_response_rr(question, &recs[ri], &ans, &ai);
 195                 W_ERROR_NOT_OK_RETURN(werror);
 196         }
 197
 198         if (ai == 0) {
 199                 return DNS_ERR(NAME_ERROR);
 200         }
 201
 202         *ancount = ai;
 203         *answers = ans;
 204
 205         return WERR_OK;
 206
 207 }
 208
 209 WERROR dns_server_process_query(struct dns_server *dns,
 210                                 TALLOC_CTX *mem_ctx,
 211                                 struct dns_name_packet *in,
 212                                 struct dns_res_rec **answers,    uint16_t *ancount,
 213                                 struct dns_res_rec **nsrecs,     uint16_t *nscount,
 214                                 struct dns_res_rec **additional, uint16_t *arcount)
 215 {
 216         uint16_t num_answers=0, num_nsrecs=0, num_additional=0;
 217         struct dns_res_rec *ans=NULL, *ns=NULL, *adds=NULL;
 218         WERROR werror;
 219
 220         if (in->qdcount != 1) {
 221                 return DNS_ERR(FORMAT_ERROR);
 222         }
 223
 224         /* Windows returns NOT_IMPLEMENTED on this as well */
 225         if (in->questions[0].question_class == DNS_QCLASS_NONE) {
 226                 return DNS_ERR(NOT_IMPLEMENTED);
 227         }
 228
 229         werror = handle_question(dns, mem_ctx, &in->questions[0], &ans, &num_answers);
 230         if(W_ERROR_EQUAL(DNS_ERR(NAME_ERROR), werror)) {
 231                 DEBUG(2, ("I don't feel responsible for '%s', forwarding\n", in->questions[0].name));
 232                 werror = ask_forwarder(mem_ctx, &in->questions[0], &ans, &num_answers,
 233                                        &ns, &num_nsrecs, &adds, &num_additional);
 234         }
 235         W_ERROR_NOT_OK_GOTO(werror, query_failed);
 236
 237         *answers = ans;
 238         *ancount = num_answers;
 239
 240         /*FIXME: Do something for these */
 241         *nsrecs  = ns;
 242         *nscount = num_nsrecs;
 243
 244         *additional = adds;
 245         *arcount    = num_additional;
 246
 247         return WERR_OK;
 248
 249 query_failed:
 250         /*FIXME: add our SOA record to nsrecs */
 251         return werror;
 252 }