source4/dns_server/dns_server.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    DNS server startup
   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 "smbd/service.h"
  25 #include "smbd/service_stream.h"
  26 #include "smbd/process_model.h"
  27 #include "lib/events/events.h"
  28 #include "lib/socket/socket.h"
  29 #include "lib/tsocket/tsocket.h"
  30 #include "libcli/util/tstream.h"
  31 #include "libcli/util/ntstatus.h"
  32 #include "system/network.h"
  33 #include "lib/stream/packet.h"
  34 #include "lib/socket/netif.h"
  35 #include "dns_server/dns_server.h"
  36 #include "param/param.h"
  37 #include "librpc/ndr/libndr.h"
  38 #include "librpc/gen_ndr/ndr_dns.h"
  39 #include "librpc/gen_ndr/ndr_dnsp.h"
  40 #include <ldb.h>
  41 #include "dsdb/samdb/samdb.h"
  42 #include "dsdb/common/util.h"
  43 #include "auth/session.h"
  44 #include "lib/util/dlinklist.h"
  45 #include "lib/util/tevent_werror.h"
  46 #include "auth/auth.h"
  47 #include "auth/credentials/credentials.h"
  48
  49 #undef DBGC_CLASS
  50 #define DBGC_CLASS DBGC_DNS
  51
  52 NTSTATUS server_service_dns_init(void);
  53
  54 /* hold information about one dns socket */
  55 struct dns_socket {
  56         struct dns_server *dns;
  57         struct tsocket_address *local_address;
  58 };
  59
  60 struct dns_udp_socket {
  61         struct dns_socket *dns_socket;
  62         struct tdgram_context *dgram;
  63         struct tevent_queue *send_queue;
  64 };
  65
  66 /*
  67   state of an open tcp connection
  68 */
  69 struct dns_tcp_connection {
  70         /* stream connection we belong to */
  71         struct stream_connection *conn;
  72
  73         /* the dns_server the connection belongs to */
  74         struct dns_socket *dns_socket;
  75
  76         struct tstream_context *tstream;
  77
  78         struct tevent_queue *send_queue;
  79 };
  80
  81 static void dns_tcp_terminate_connection(struct dns_tcp_connection *dnsconn, const char *reason)
  82 {
  83         stream_terminate_connection(dnsconn->conn, reason);
  84 }
  85
  86 static void dns_tcp_recv(struct stream_connection *conn, uint16_t flags)
  87 {
  88         struct dns_tcp_connection *dnsconn = talloc_get_type(conn->private_data,
  89                                                              struct dns_tcp_connection);
  90         /* this should never be triggered! */
  91         dns_tcp_terminate_connection(dnsconn, "dns_tcp_recv: called");
  92 }
  93
  94 static void dns_tcp_send(struct stream_connection *conn, uint16_t flags)
  95 {
  96         struct dns_tcp_connection *dnsconn = talloc_get_type(conn->private_data,
  97                                                              struct dns_tcp_connection);
  98         /* this should never be triggered! */
  99         dns_tcp_terminate_connection(dnsconn, "dns_tcp_send: called");
 100 }
 101
 102 struct dns_process_state {
 103         DATA_BLOB *in;
 104         struct dns_server *dns;
 105         struct dns_name_packet in_packet;
 106         struct dns_request_state state;
 107         uint16_t dns_err;
 108         struct dns_name_packet out_packet;
 109         DATA_BLOB out;
 110 };
 111
 112 static void dns_process_done(struct tevent_req *subreq);
 113
 114 static struct tevent_req *dns_process_send(TALLOC_CTX *mem_ctx,
 115                                            struct tevent_context *ev,
 116                                            struct dns_server *dns,
 117                                            DATA_BLOB *in)
 118 {
 119         struct tevent_req *req, *subreq;
 120         struct dns_process_state *state;
 121         enum ndr_err_code ndr_err;
 122         WERROR ret;
 123         const char *forwarder = lpcfg_dns_forwarder(dns->task->lp_ctx);
 124         req = tevent_req_create(mem_ctx, &state, struct dns_process_state);
 125         if (req == NULL) {
 126                 return NULL;
 127         }
 128         state->in = in;
 129
 130         state->dns = dns;
 131
 132         if (in->length < 12) {
 133                 tevent_req_werror(req, WERR_INVALID_PARAM);
 134                 return tevent_req_post(req, ev);
 135         }
 136         dump_data(8, in->data, in->length);
 137
 138         ndr_err = ndr_pull_struct_blob(
 139                 in, state, &state->in_packet,
 140                 (ndr_pull_flags_fn_t)ndr_pull_dns_name_packet);
 141
 142         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 143                 state->dns_err = DNS_RCODE_FORMERR;
 144                 tevent_req_done(req);
 145                 return tevent_req_post(req, ev);
 146         }
 147         if (DEBUGLVL(8)) {
 148                 NDR_PRINT_DEBUG(dns_name_packet, &state->in_packet);
 149         }
 150
 151         ret = dns_verify_tsig(dns, state, &state->state, &state->in_packet, in);
 152         if (!W_ERROR_IS_OK(ret)) {
 153                 DEBUG(1, ("Failed to verify TSIG!\n"));
 154                 state->dns_err = werr_to_dns_err(ret);
 155                 tevent_req_done(req);
 156                 return tevent_req_post(req, ev);
 157         }
 158
 159         state->state.flags = state->in_packet.operation;
 160         state->state.flags |= DNS_FLAG_REPLY;
 161
 162
 163         if (forwarder && *forwarder) {
 164                 state->state.flags |= DNS_FLAG_RECURSION_AVAIL;
 165         }
 166
 167         state->out_packet = state->in_packet;
 168
 169         switch (state->in_packet.operation & DNS_OPCODE) {
 170         case DNS_OPCODE_QUERY:
 171                 subreq = dns_server_process_query_send(
 172                         state, ev, dns, &state->state, &state->in_packet);
 173                 if (tevent_req_nomem(subreq, req)) {
 174                         return tevent_req_post(req, ev);
 175                 }
 176                 tevent_req_set_callback(subreq, dns_process_done, req);
 177                 return req;
 178         case DNS_OPCODE_UPDATE:
 179                 ret = dns_server_process_update(
 180                         dns, &state->state, state, &state->in_packet,
 181                         &state->out_packet.answers, &state->out_packet.ancount,
 182                         &state->out_packet.nsrecs,  &state->out_packet.nscount,
 183                         &state->out_packet.additional,
 184                         &state->out_packet.arcount);
 185                 break;
 186         default:
 187                 ret = WERR_DNS_ERROR_RCODE_NOT_IMPLEMENTED;
 188         }
 189         if (!W_ERROR_IS_OK(ret)) {
 190                 state->dns_err = werr_to_dns_err(ret);
 191         }
 192         tevent_req_done(req);
 193         return tevent_req_post(req, ev);
 194 }
 195
 196 static void dns_process_done(struct tevent_req *subreq)
 197 {
 198         struct tevent_req *req = tevent_req_callback_data(
 199                 subreq, struct tevent_req);
 200         struct dns_process_state *state = tevent_req_data(
 201                 req, struct dns_process_state);
 202         WERROR ret;
 203
 204         ret = dns_server_process_query_recv(
 205                 subreq, state,
 206                 &state->out_packet.answers, &state->out_packet.ancount,
 207                 &state->out_packet.nsrecs,  &state->out_packet.nscount,
 208                 &state->out_packet.additional, &state->out_packet.arcount);
 209         TALLOC_FREE(subreq);
 210
 211         if (!W_ERROR_IS_OK(ret)) {
 212                 state->dns_err = werr_to_dns_err(ret);
 213         }
 214         tevent_req_done(req);
 215 }
 216
 217 static WERROR dns_process_recv(struct tevent_req *req, TALLOC_CTX *mem_ctx,
 218                                DATA_BLOB *out)
 219 {
 220         struct dns_process_state *state = tevent_req_data(
 221                 req, struct dns_process_state);
 222         enum ndr_err_code ndr_err;
 223         WERROR ret;
 224
 225         if (tevent_req_is_werror(req, &ret)) {
 226                 return ret;
 227         }
 228         if (state->dns_err != DNS_RCODE_OK) {
 229                 goto drop;
 230         }
 231         state->out_packet.operation |= state->state.flags;
 232
 233         if (state->state.sign) {
 234                 ret = dns_sign_tsig(state->dns, mem_ctx, &state->state,
 235                                     &state->out_packet, 0);
 236                 if (!W_ERROR_IS_OK(ret)) {
 237                         state->dns_err = DNS_RCODE_SERVFAIL;
 238                         goto drop;
 239                 }
 240         }
 241
 242         ndr_err = ndr_push_struct_blob(
 243                 out, mem_ctx, &state->out_packet,
 244                 (ndr_push_flags_fn_t)ndr_push_dns_name_packet);
 245         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 246                 DEBUG(1, ("Failed to push packet: %s!\n",
 247                           ndr_errstr(ndr_err)));
 248                 state->dns_err = DNS_RCODE_SERVFAIL;
 249                 goto drop;
 250         }
 251         return WERR_OK;
 252
 253 drop:
 254         *out = data_blob_talloc(mem_ctx, state->in->data, state->in->length);
 255         if (out->data == NULL) {
 256                 return WERR_NOMEM;
 257         }
 258         out->data[2] |= 0x80; /* Toggle DNS_FLAG_REPLY */
 259         out->data[3] |= state->dns_err;
 260         return WERR_OK;
 261 }
 262
 263 struct dns_tcp_call {
 264         struct dns_tcp_connection *dns_conn;
 265         DATA_BLOB in;
 266         DATA_BLOB out;
 267         uint8_t out_hdr[4];
 268         struct iovec out_iov[2];
 269 };
 270
 271 static void dns_tcp_call_process_done(struct tevent_req *subreq);
 272 static void dns_tcp_call_writev_done(struct tevent_req *subreq);
 273
 274 static void dns_tcp_call_loop(struct tevent_req *subreq)
 275 {
 276         struct dns_tcp_connection *dns_conn = tevent_req_callback_data(subreq,
 277                                       struct dns_tcp_connection);
 278         struct dns_server *dns = dns_conn->dns_socket->dns;
 279         struct dns_tcp_call *call;
 280         NTSTATUS status;
 281
 282         call = talloc(dns_conn, struct dns_tcp_call);
 283         if (call == NULL) {
 284                 dns_tcp_terminate_connection(dns_conn, "dns_tcp_call_loop: "
 285                                 "no memory for dns_tcp_call");
 286                 return;
 287         }
 288         call->dns_conn = dns_conn;
 289
 290         status = tstream_read_pdu_blob_recv(subreq,
 291                                             call,
 292                                             &call->in);
 293         TALLOC_FREE(subreq);
 294         if (!NT_STATUS_IS_OK(status)) {
 295                 const char *reason;
 296
 297                 reason = talloc_asprintf(call, "dns_tcp_call_loop: "
 298                                          "tstream_read_pdu_blob_recv() - %s",
 299                                          nt_errstr(status));
 300                 if (!reason) {
 301                         reason = nt_errstr(status);
 302                 }
 303
 304                 dns_tcp_terminate_connection(dns_conn, reason);
 305                 return;
 306         }
 307
 308         DEBUG(10,("Received DNS TCP packet of length %lu from %s\n",
 309                  (long) call->in.length,
 310                  tsocket_address_string(dns_conn->conn->remote_address, call)));
 311
 312         /* skip length header */
 313         call->in.data += 2;
 314         call->in.length -= 2;
 315
 316         subreq = dns_process_send(call, dns->task->event_ctx, dns,
 317                                   &call->in);
 318         if (subreq == NULL) {
 319                 dns_tcp_terminate_connection(
 320                         dns_conn, "dns_tcp_call_loop: dns_process_send "
 321                         "failed\n");
 322                 return;
 323         }
 324         tevent_req_set_callback(subreq, dns_tcp_call_process_done, call);
 325
 326         /*
 327          * The dns tcp pdu's has the length as 2 byte (initial_read_size),
 328          * packet_full_request_u16 provides the pdu length then.
 329          */
 330         subreq = tstream_read_pdu_blob_send(dns_conn,
 331                                             dns_conn->conn->event.ctx,
 332                                             dns_conn->tstream,
 333                                             2, /* initial_read_size */
 334                                             packet_full_request_u16,
 335                                             dns_conn);
 336         if (subreq == NULL) {
 337                 dns_tcp_terminate_connection(dns_conn, "dns_tcp_call_loop: "
 338                                 "no memory for tstream_read_pdu_blob_send");
 339                 return;
 340         }
 341         tevent_req_set_callback(subreq, dns_tcp_call_loop, dns_conn);
 342 }
 343
 344 static void dns_tcp_call_process_done(struct tevent_req *subreq)
 345 {
 346         struct dns_tcp_call *call = tevent_req_callback_data(subreq,
 347                         struct dns_tcp_call);
 348         struct dns_tcp_connection *dns_conn = call->dns_conn;
 349         WERROR err;
 350
 351         err = dns_process_recv(subreq, call, &call->out);
 352         TALLOC_FREE(subreq);
 353         if (!W_ERROR_IS_OK(err)) {
 354                 DEBUG(1, ("dns_process returned %s\n", win_errstr(err)));
 355                 dns_tcp_terminate_connection(dns_conn,
 356                                 "dns_tcp_call_loop: process function failed");
 357                 return;
 358         }
 359
 360         /* First add the length of the out buffer */
 361         RSSVAL(call->out_hdr, 0, call->out.length);
 362         call->out_iov[0].iov_base = (char *) call->out_hdr;
 363         call->out_iov[0].iov_len = 2;
 364
 365         call->out_iov[1].iov_base = (char *) call->out.data;
 366         call->out_iov[1].iov_len = call->out.length;
 367
 368         subreq = tstream_writev_queue_send(call,
 369                                            dns_conn->conn->event.ctx,
 370                                            dns_conn->tstream,
 371                                            dns_conn->send_queue,
 372                                            call->out_iov, 2);
 373         if (subreq == NULL) {
 374                 dns_tcp_terminate_connection(dns_conn, "dns_tcp_call_loop: "
 375                                 "no memory for tstream_writev_queue_send");
 376                 return;
 377         }
 378         tevent_req_set_callback(subreq, dns_tcp_call_writev_done, call);
 379 }
 380
 381 static void dns_tcp_call_writev_done(struct tevent_req *subreq)
 382 {
 383         struct dns_tcp_call *call = tevent_req_callback_data(subreq,
 384                         struct dns_tcp_call);
 385         int sys_errno;
 386         int rc;
 387
 388         rc = tstream_writev_queue_recv(subreq, &sys_errno);
 389         TALLOC_FREE(subreq);
 390         if (rc == -1) {
 391                 const char *reason;
 392
 393                 reason = talloc_asprintf(call, "dns_tcp_call_writev_done: "
 394                                          "tstream_writev_queue_recv() - %d:%s",
 395                                          sys_errno, strerror(sys_errno));
 396                 if (!reason) {
 397                         reason = "dns_tcp_call_writev_done: tstream_writev_queue_recv() failed";
 398                 }
 399
 400                 dns_tcp_terminate_connection(call->dns_conn, reason);
 401                 return;
 402         }
 403
 404         /* We don't care about errors */
 405
 406         talloc_free(call);
 407 }
 408
 409 /*
 410   called when we get a new connection
 411 */
 412 static void dns_tcp_accept(struct stream_connection *conn)
 413 {
 414         struct dns_socket *dns_socket;
 415         struct dns_tcp_connection *dns_conn;
 416         struct tevent_req *subreq;
 417         int rc;
 418
 419         dns_conn = talloc_zero(conn, struct dns_tcp_connection);
 420         if (dns_conn == NULL) {
 421                 stream_terminate_connection(conn,
 422                                 "dns_tcp_accept: out of memory");
 423                 return;
 424         }
 425
 426         dns_conn->send_queue = tevent_queue_create(conn, "dns_tcp_accept");
 427         if (dns_conn->send_queue == NULL) {
 428                 stream_terminate_connection(conn,
 429                                 "dns_tcp_accept: out of memory");
 430                 return;
 431         }
 432
 433         dns_socket = talloc_get_type(conn->private_data, struct dns_socket);
 434
 435         TALLOC_FREE(conn->event.fde);
 436
 437         rc = tstream_bsd_existing_socket(dns_conn,
 438                         socket_get_fd(conn->socket),
 439                         &dns_conn->tstream);
 440         if (rc < 0) {
 441                 stream_terminate_connection(conn,
 442                                 "dns_tcp_accept: out of memory");
 443                 return;
 444         }
 445
 446         dns_conn->conn = conn;
 447         dns_conn->dns_socket = dns_socket;
 448         conn->private_data = dns_conn;
 449
 450         /*
 451          * The dns tcp pdu's has the length as 2 byte (initial_read_size),
 452          * packet_full_request_u16 provides the pdu length then.
 453          */
 454         subreq = tstream_read_pdu_blob_send(dns_conn,
 455                                             dns_conn->conn->event.ctx,
 456                                             dns_conn->tstream,
 457                                             2, /* initial_read_size */
 458                                             packet_full_request_u16,
 459                                             dns_conn);
 460         if (subreq == NULL) {
 461                 dns_tcp_terminate_connection(dns_conn, "dns_tcp_accept: "
 462                                 "no memory for tstream_read_pdu_blob_send");
 463                 return;
 464         }
 465         tevent_req_set_callback(subreq, dns_tcp_call_loop, dns_conn);
 466 }
 467
 468 static const struct stream_server_ops dns_tcp_stream_ops = {
 469         .name                   = "dns_tcp",
 470         .accept_connection      = dns_tcp_accept,
 471         .recv_handler           = dns_tcp_recv,
 472         .send_handler           = dns_tcp_send
 473 };
 474
 475 struct dns_udp_call {
 476         struct dns_udp_socket *sock;
 477         struct tsocket_address *src;
 478         DATA_BLOB in;
 479         DATA_BLOB out;
 480 };
 481
 482 static void dns_udp_call_process_done(struct tevent_req *subreq);
 483 static void dns_udp_call_sendto_done(struct tevent_req *subreq);
 484
 485 static void dns_udp_call_loop(struct tevent_req *subreq)
 486 {
 487         struct dns_udp_socket *sock = tevent_req_callback_data(subreq,
 488                                       struct dns_udp_socket);
 489         struct dns_server *dns = sock->dns_socket->dns;
 490         struct dns_udp_call *call;
 491         uint8_t *buf;
 492         ssize_t len;
 493         int sys_errno;
 494
 495         call = talloc(sock, struct dns_udp_call);
 496         if (call == NULL) {
 497                 talloc_free(call);
 498                 goto done;
 499         }
 500         call->sock = sock;
 501
 502         len = tdgram_recvfrom_recv(subreq, &sys_errno,
 503                                    call, &buf, &call->src);
 504         TALLOC_FREE(subreq);
 505         if (len == -1) {
 506                 talloc_free(call);
 507                 goto done;
 508         }
 509
 510         call->in.data = buf;
 511         call->in.length = len;
 512
 513         DEBUG(10,("Received DNS UDP packet of length %lu from %s\n",
 514                  (long)call->in.length,
 515                  tsocket_address_string(call->src, call)));
 516
 517         subreq = dns_process_send(call, dns->task->event_ctx, dns,
 518                                   &call->in);
 519         if (subreq == NULL) {
 520                 TALLOC_FREE(call);
 521                 goto done;
 522         }
 523         tevent_req_set_callback(subreq, dns_udp_call_process_done, call);
 524
 525 done:
 526         subreq = tdgram_recvfrom_send(sock,
 527                                       sock->dns_socket->dns->task->event_ctx,
 528                                       sock->dgram);
 529         if (subreq == NULL) {
 530                 task_server_terminate(sock->dns_socket->dns->task,
 531                                       "no memory for tdgram_recvfrom_send",
 532                                       true);
 533                 return;
 534         }
 535         tevent_req_set_callback(subreq, dns_udp_call_loop, sock);
 536 }
 537
 538 static void dns_udp_call_process_done(struct tevent_req *subreq)
 539 {
 540         struct dns_udp_call *call = tevent_req_callback_data(
 541                 subreq, struct dns_udp_call);
 542         struct dns_udp_socket *sock = call->sock;
 543         struct dns_server *dns = sock->dns_socket->dns;
 544         WERROR err;
 545
 546         err = dns_process_recv(subreq, call, &call->out);
 547         TALLOC_FREE(subreq);
 548         if (!W_ERROR_IS_OK(err)) {
 549                 DEBUG(1, ("dns_process returned %s\n", win_errstr(err)));
 550                 TALLOC_FREE(call);
 551                 return;
 552         }
 553
 554         subreq = tdgram_sendto_queue_send(call,
 555                                           dns->task->event_ctx,
 556                                           sock->dgram,
 557                                           sock->send_queue,
 558                                           call->out.data,
 559                                           call->out.length,
 560                                           call->src);
 561         if (subreq == NULL) {
 562                 talloc_free(call);
 563                 return;
 564         }
 565         tevent_req_set_callback(subreq, dns_udp_call_sendto_done, call);
 566
 567 }
 568 static void dns_udp_call_sendto_done(struct tevent_req *subreq)
 569 {
 570         struct dns_udp_call *call = tevent_req_callback_data(subreq,
 571                                        struct dns_udp_call);
 572         int sys_errno;
 573
 574         tdgram_sendto_queue_recv(subreq, &sys_errno);
 575
 576         /* We don't care about errors */
 577
 578         talloc_free(call);
 579 }
 580
 581 /*
 582   start listening on the given address
 583 */
 584 static NTSTATUS dns_add_socket(struct dns_server *dns,
 585                                const struct model_ops *model_ops,
 586                                const char *name,
 587                                const char *address,
 588                                uint16_t port)
 589 {
 590         struct dns_socket *dns_socket;
 591         struct dns_udp_socket *dns_udp_socket;
 592         struct tevent_req *udpsubreq;
 593         NTSTATUS status;
 594         int ret;
 595
 596         dns_socket = talloc(dns, struct dns_socket);
 597         NT_STATUS_HAVE_NO_MEMORY(dns_socket);
 598
 599         dns_socket->dns = dns;
 600
 601         ret = tsocket_address_inet_from_strings(dns_socket, "ip",
 602                                                 address, port,
 603                                                 &dns_socket->local_address);
 604         if (ret != 0) {
 605                 status = map_nt_error_from_unix_common(errno);
 606                 return status;
 607         }
 608
 609         status = stream_setup_socket(dns->task,
 610                                      dns->task->event_ctx,
 611                                      dns->task->lp_ctx,
 612                                      model_ops,
 613                                      &dns_tcp_stream_ops,
 614                                      "ip", address, &port,
 615                                      lpcfg_socket_options(dns->task->lp_ctx),
 616                                      dns_socket);
 617         if (!NT_STATUS_IS_OK(status)) {
 618                 DEBUG(0,("Failed to bind to %s:%u TCP - %s\n",
 619                          address, port, nt_errstr(status)));
 620                 talloc_free(dns_socket);
 621                 return status;
 622         }
 623
 624         dns_udp_socket = talloc(dns_socket, struct dns_udp_socket);
 625         NT_STATUS_HAVE_NO_MEMORY(dns_udp_socket);
 626
 627         dns_udp_socket->dns_socket = dns_socket;
 628
 629         ret = tdgram_inet_udp_socket(dns_socket->local_address,
 630                                      NULL,
 631                                      dns_udp_socket,
 632                                      &dns_udp_socket->dgram);
 633         if (ret != 0) {
 634                 status = map_nt_error_from_unix_common(errno);
 635                 DEBUG(0,("Failed to bind to %s:%u UDP - %s\n",
 636                          address, port, nt_errstr(status)));
 637                 return status;
 638         }
 639
 640         dns_udp_socket->send_queue = tevent_queue_create(dns_udp_socket,
 641                                                          "dns_udp_send_queue");
 642         NT_STATUS_HAVE_NO_MEMORY(dns_udp_socket->send_queue);
 643
 644         udpsubreq = tdgram_recvfrom_send(dns_udp_socket,
 645                                          dns->task->event_ctx,
 646                                          dns_udp_socket->dgram);
 647         NT_STATUS_HAVE_NO_MEMORY(udpsubreq);
 648         tevent_req_set_callback(udpsubreq, dns_udp_call_loop, dns_udp_socket);
 649
 650         return NT_STATUS_OK;
 651 }
 652
 653 /*
 654   setup our listening sockets on the configured network interfaces
 655 */
 656 static NTSTATUS dns_startup_interfaces(struct dns_server *dns, struct loadparm_context *lp_ctx,
 657                                        struct interface *ifaces)
 658 {
 659         const struct model_ops *model_ops;
 660         int num_interfaces;
 661         TALLOC_CTX *tmp_ctx = talloc_new(dns);
 662         NTSTATUS status;
 663         int i;
 664
 665         /* within the dns task we want to be a single process, so
 666            ask for the single process model ops and pass these to the
 667            stream_setup_socket() call. */
 668         model_ops = process_model_startup("single");
 669         if (!model_ops) {
 670                 DEBUG(0,("Can't find 'single' process model_ops\n"));
 671                 return NT_STATUS_INTERNAL_ERROR;
 672         }
 673
 674         if (ifaces != NULL) {
 675                 num_interfaces = iface_list_count(ifaces);
 676
 677                 for (i=0; i<num_interfaces; i++) {
 678                         const char *address = talloc_strdup(tmp_ctx,
 679                                                             iface_list_n_ip(ifaces, i));
 680
 681                         status = dns_add_socket(dns, model_ops, "dns", address,
 682                                                 DNS_SERVICE_PORT);
 683                         NT_STATUS_NOT_OK_RETURN(status);
 684                 }
 685         } else {
 686                 const char **wcard;
 687                 wcard = iface_list_wildcard(tmp_ctx, lp_ctx);
 688                 if (wcard == NULL) {
 689                         DEBUG(0, ("No wildcard address available\n"));
 690                         return NT_STATUS_INTERNAL_ERROR;
 691                 }
 692                 for (i = 0; wcard[i] != NULL; i++) {
 693                         status = dns_add_socket(dns, model_ops, "dns", wcard[i],
 694                                                 DNS_SERVICE_PORT);
 695                         NT_STATUS_NOT_OK_RETURN(status);
 696                 }
 697         }
 698
 699         talloc_free(tmp_ctx);
 700
 701         return NT_STATUS_OK;
 702 }
 703
 704 static int dns_server_sort_zones(struct ldb_message **m1, struct ldb_message **m2)
 705 {
 706         const char *n1, *n2;
 707         size_t l1, l2;
 708
 709         n1 = ldb_msg_find_attr_as_string(*m1, "name", NULL);
 710         n2 = ldb_msg_find_attr_as_string(*m2, "name", NULL);
 711
 712         l1 = strlen(n1);
 713         l2 = strlen(n2);
 714
 715         /* If the string lengths are not equal just sort by length */
 716         if (l1 != l2) {
 717                 /* If m1 is the larger zone name, return it first */
 718                 return l2 - l1;
 719         }
 720
 721         /*TODO: We need to compare DNs here, we want the DomainDNSZones first */
 722         return 0;
 723 }
 724
 725 static struct dns_server_tkey_store *tkey_store_init(TALLOC_CTX *mem_ctx,
 726                                                      uint16_t size)
 727 {
 728         struct dns_server_tkey_store *buffer = talloc_zero(mem_ctx,
 729                                                 struct dns_server_tkey_store);
 730
 731         if (buffer == NULL) {
 732                 return NULL;
 733         }
 734
 735         buffer->size = size;
 736         buffer->next_idx = 0;
 737
 738         buffer->tkeys = talloc_zero_array(buffer, struct dns_server_tkey *, size);
 739         if (buffer->tkeys == NULL) {
 740                 TALLOC_FREE(buffer);
 741         }
 742
 743         return buffer;
 744 }
 745
 746 static void dns_task_init(struct task_server *task)
 747 {
 748         struct dns_server *dns;
 749         NTSTATUS status;
 750         struct interface *ifaces = NULL;
 751         int ret;
 752         struct ldb_result *res;
 753         static const char * const attrs[] = { "name", NULL};
 754         static const char * const attrs_none[] = { NULL};
 755         unsigned int i;
 756         struct ldb_message *dns_acc;
 757         char *hostname_lower;
 758         char *dns_spn;
 759
 760         switch (lpcfg_server_role(task->lp_ctx)) {
 761         case ROLE_STANDALONE:
 762                 task_server_terminate(task, "dns: no DNS required in standalone configuration", false);
 763                 return;
 764         case ROLE_DOMAIN_MEMBER:
 765                 task_server_terminate(task, "dns: no DNS required in member server configuration", false);
 766                 return;
 767         case ROLE_ACTIVE_DIRECTORY_DC:
 768                 /* Yes, we want a DNS */
 769                 break;
 770         }
 771
 772         if (lpcfg_interfaces(task->lp_ctx) && lpcfg_bind_interfaces_only(task->lp_ctx)) {
 773                 load_interface_list(task, task->lp_ctx, &ifaces);
 774
 775                 if (iface_list_count(ifaces) == 0) {
 776                         task_server_terminate(task, "dns: no network interfaces configured", false);
 777                         return;
 778                 }
 779         }
 780
 781         task_server_set_title(task, "task[dns]");
 782
 783         dns = talloc_zero(task, struct dns_server);
 784         if (dns == NULL) {
 785                 task_server_terminate(task, "dns: out of memory", true);
 786                 return;
 787         }
 788
 789         dns->task = task;
 790
 791         dns->server_credentials = cli_credentials_init(dns);
 792         if (!dns->server_credentials) {
 793                 task_server_terminate(task, "Failed to init server credentials\n", true);
 794                 return;
 795         }
 796
 797         dns->samdb = samdb_connect(dns, dns->task->event_ctx, dns->task->lp_ctx,
 798                               system_session(dns->task->lp_ctx), 0);
 799         if (!dns->samdb) {
 800                 task_server_terminate(task, "dns: samdb_connect failed", true);
 801                 return;
 802         }
 803
 804         cli_credentials_set_conf(dns->server_credentials, task->lp_ctx);
 805
 806         hostname_lower = strlower_talloc(dns, lpcfg_netbios_name(task->lp_ctx));
 807         dns_spn = talloc_asprintf(dns, "DNS/%s.%s",
 808                                   hostname_lower,
 809                                   lpcfg_dnsdomain(task->lp_ctx));
 810         TALLOC_FREE(hostname_lower);
 811
 812         ret = dsdb_search_one(dns->samdb, dns, &dns_acc,
 813                               ldb_get_default_basedn(dns->samdb), LDB_SCOPE_SUBTREE,
 814                               attrs_none, 0, "(servicePrincipalName=%s)",
 815                               dns_spn);
 816         if (ret == LDB_SUCCESS) {
 817                 TALLOC_FREE(dns_acc);
 818                 if (!dns_spn) {
 819                         task_server_terminate(task, "dns: talloc_asprintf failed", true);
 820                         return;
 821                 }
 822                 status = cli_credentials_set_stored_principal(dns->server_credentials, task->lp_ctx, dns_spn);
 823                 if (!NT_STATUS_IS_OK(status)) {
 824                         task_server_terminate(task,
 825                                               talloc_asprintf(task, "Failed to obtain server credentials for DNS, "
 826                                                               "despite finding it in the samdb! %s\n",
 827                                                               nt_errstr(status)),
 828                                               true);
 829                         return;
 830                 }
 831         } else {
 832                 TALLOC_FREE(dns_spn);
 833                 status = cli_credentials_set_machine_account(dns->server_credentials, task->lp_ctx);
 834                 if (!NT_STATUS_IS_OK(status)) {
 835                         task_server_terminate(task,
 836                                               talloc_asprintf(task, "Failed to obtain server credentials, perhaps a standalone server?: %s\n",
 837                                                               nt_errstr(status)),
 838                                               true);
 839                         return;
 840                 }
 841         }
 842
 843         dns->tkeys = tkey_store_init(dns, TKEY_BUFFER_SIZE);
 844         if (!dns->tkeys) {
 845                 task_server_terminate(task, "Failed to allocate tkey storage\n", true);
 846                 return;
 847         }
 848
 849         // TODO: this search does not work against windows
 850         ret = dsdb_search(dns->samdb, dns, &res, NULL, LDB_SCOPE_SUBTREE,
 851                           attrs, DSDB_SEARCH_SEARCH_ALL_PARTITIONS, "(objectClass=dnsZone)");
 852         if (ret != LDB_SUCCESS) {
 853                 task_server_terminate(task,
 854                                       "dns: failed to look up root DNS zones",
 855                                       true);
 856                 return;
 857         }
 858
 859         TYPESAFE_QSORT(res->msgs, res->count, dns_server_sort_zones);
 860
 861         for (i=0; i < res->count; i++) {
 862                 struct dns_server_zone *z;
 863
 864                 z = talloc_zero(dns, struct dns_server_zone);
 865                 if (z == NULL) {
 866                         task_server_terminate(task, "dns failed to allocate memory", true);
 867                 }
 868
 869                 z->name = ldb_msg_find_attr_as_string(res->msgs[i], "name", NULL);
 870                 z->dn = talloc_move(z, &res->msgs[i]->dn);
 871                 /*
 872                  * Ignore the RootDNSServers zone and zones that we don't support yet
 873                  * RootDNSServers should never be returned (Windows DNS server don't)
 874                  * ..TrustAnchors should never be returned as is, (Windows returns
 875                  * TrustAnchors) and for the moment we don't support DNSSEC so we'd better
 876                  * not return this zone.
 877                  */
 878                 if ((strcmp(z->name, "RootDNSServers") == 0) ||
 879                     (strcmp(z->name, "..TrustAnchors") == 0))
 880                 {
 881                         DEBUG(10, ("Ignoring zone %s\n", z->name));
 882                         talloc_free(z);
 883                         continue;
 884                 }
 885                 DLIST_ADD_END(dns->zones, z, NULL);
 886         }
 887
 888         status = dns_startup_interfaces(dns, task->lp_ctx, ifaces);
 889         if (!NT_STATUS_IS_OK(status)) {
 890                 task_server_terminate(task, "dns failed to setup interfaces", true);
 891                 return;
 892         }
 893 }
 894
 895 NTSTATUS server_service_dns_init(void)
 896 {
 897         return register_server_service("dns", dns_task_init);
 898 }