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_dbgc(DBGC_DNS, 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 (DEBUGLVLC(DBGC_DNS, 8)) {
 148                 NDR_PRINT_DEBUGC(DBGC_DNS, 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         if (DEBUGLVLC(DBGC_DNS, 8)) {
 243                 NDR_PRINT_DEBUGC(DBGC_DNS, dns_name_packet, &state->out_packet);
 244         }
 245
 246         ndr_err = ndr_push_struct_blob(
 247                 out, mem_ctx, &state->out_packet,
 248                 (ndr_push_flags_fn_t)ndr_push_dns_name_packet);
 249         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 250                 DEBUG(1, ("Failed to push packet: %s!\n",
 251                           ndr_errstr(ndr_err)));
 252                 state->dns_err = DNS_RCODE_SERVFAIL;
 253                 goto drop;
 254         }
 255         return WERR_OK;
 256
 257 drop:
 258         *out = data_blob_talloc(mem_ctx, state->in->data, state->in->length);
 259         if (out->data == NULL) {
 260                 return WERR_NOMEM;
 261         }
 262         out->data[2] |= 0x80; /* Toggle DNS_FLAG_REPLY */
 263         out->data[3] |= state->dns_err;
 264         return WERR_OK;
 265 }
 266
 267 struct dns_tcp_call {
 268         struct dns_tcp_connection *dns_conn;
 269         DATA_BLOB in;
 270         DATA_BLOB out;
 271         uint8_t out_hdr[4];
 272         struct iovec out_iov[2];
 273 };
 274
 275 static void dns_tcp_call_process_done(struct tevent_req *subreq);
 276 static void dns_tcp_call_writev_done(struct tevent_req *subreq);
 277
 278 static void dns_tcp_call_loop(struct tevent_req *subreq)
 279 {
 280         struct dns_tcp_connection *dns_conn = tevent_req_callback_data(subreq,
 281                                       struct dns_tcp_connection);
 282         struct dns_server *dns = dns_conn->dns_socket->dns;
 283         struct dns_tcp_call *call;
 284         NTSTATUS status;
 285
 286         call = talloc(dns_conn, struct dns_tcp_call);
 287         if (call == NULL) {
 288                 dns_tcp_terminate_connection(dns_conn, "dns_tcp_call_loop: "
 289                                 "no memory for dns_tcp_call");
 290                 return;
 291         }
 292         call->dns_conn = dns_conn;
 293
 294         status = tstream_read_pdu_blob_recv(subreq,
 295                                             call,
 296                                             &call->in);
 297         TALLOC_FREE(subreq);
 298         if (!NT_STATUS_IS_OK(status)) {
 299                 const char *reason;
 300
 301                 reason = talloc_asprintf(call, "dns_tcp_call_loop: "
 302                                          "tstream_read_pdu_blob_recv() - %s",
 303                                          nt_errstr(status));
 304                 if (!reason) {
 305                         reason = nt_errstr(status);
 306                 }
 307
 308                 dns_tcp_terminate_connection(dns_conn, reason);
 309                 return;
 310         }
 311
 312         DEBUG(10,("Received DNS TCP packet of length %lu from %s\n",
 313                  (long) call->in.length,
 314                  tsocket_address_string(dns_conn->conn->remote_address, call)));
 315
 316         /* skip length header */
 317         call->in.data += 2;
 318         call->in.length -= 2;
 319
 320         subreq = dns_process_send(call, dns->task->event_ctx, dns,
 321                                   &call->in);
 322         if (subreq == NULL) {
 323                 dns_tcp_terminate_connection(
 324                         dns_conn, "dns_tcp_call_loop: dns_process_send "
 325                         "failed\n");
 326                 return;
 327         }
 328         tevent_req_set_callback(subreq, dns_tcp_call_process_done, call);
 329
 330         /*
 331          * The dns tcp pdu's has the length as 2 byte (initial_read_size),
 332          * packet_full_request_u16 provides the pdu length then.
 333          */
 334         subreq = tstream_read_pdu_blob_send(dns_conn,
 335                                             dns_conn->conn->event.ctx,
 336                                             dns_conn->tstream,
 337                                             2, /* initial_read_size */
 338                                             packet_full_request_u16,
 339                                             dns_conn);
 340         if (subreq == NULL) {
 341                 dns_tcp_terminate_connection(dns_conn, "dns_tcp_call_loop: "
 342                                 "no memory for tstream_read_pdu_blob_send");
 343                 return;
 344         }
 345         tevent_req_set_callback(subreq, dns_tcp_call_loop, dns_conn);
 346 }
 347
 348 static void dns_tcp_call_process_done(struct tevent_req *subreq)
 349 {
 350         struct dns_tcp_call *call = tevent_req_callback_data(subreq,
 351                         struct dns_tcp_call);
 352         struct dns_tcp_connection *dns_conn = call->dns_conn;
 353         WERROR err;
 354
 355         err = dns_process_recv(subreq, call, &call->out);
 356         TALLOC_FREE(subreq);
 357         if (!W_ERROR_IS_OK(err)) {
 358                 DEBUG(1, ("dns_process returned %s\n", win_errstr(err)));
 359                 dns_tcp_terminate_connection(dns_conn,
 360                                 "dns_tcp_call_loop: process function failed");
 361                 return;
 362         }
 363
 364         /* First add the length of the out buffer */
 365         RSSVAL(call->out_hdr, 0, call->out.length);
 366         call->out_iov[0].iov_base = (char *) call->out_hdr;
 367         call->out_iov[0].iov_len = 2;
 368
 369         call->out_iov[1].iov_base = (char *) call->out.data;
 370         call->out_iov[1].iov_len = call->out.length;
 371
 372         subreq = tstream_writev_queue_send(call,
 373                                            dns_conn->conn->event.ctx,
 374                                            dns_conn->tstream,
 375                                            dns_conn->send_queue,
 376                                            call->out_iov, 2);
 377         if (subreq == NULL) {
 378                 dns_tcp_terminate_connection(dns_conn, "dns_tcp_call_loop: "
 379                                 "no memory for tstream_writev_queue_send");
 380                 return;
 381         }
 382         tevent_req_set_callback(subreq, dns_tcp_call_writev_done, call);
 383 }
 384
 385 static void dns_tcp_call_writev_done(struct tevent_req *subreq)
 386 {
 387         struct dns_tcp_call *call = tevent_req_callback_data(subreq,
 388                         struct dns_tcp_call);
 389         int sys_errno;
 390         int rc;
 391
 392         rc = tstream_writev_queue_recv(subreq, &sys_errno);
 393         TALLOC_FREE(subreq);
 394         if (rc == -1) {
 395                 const char *reason;
 396
 397                 reason = talloc_asprintf(call, "dns_tcp_call_writev_done: "
 398                                          "tstream_writev_queue_recv() - %d:%s",
 399                                          sys_errno, strerror(sys_errno));
 400                 if (!reason) {
 401                         reason = "dns_tcp_call_writev_done: tstream_writev_queue_recv() failed";
 402                 }
 403
 404                 dns_tcp_terminate_connection(call->dns_conn, reason);
 405                 return;
 406         }
 407
 408         /* We don't care about errors */
 409
 410         talloc_free(call);
 411 }
 412
 413 /*
 414   called when we get a new connection
 415 */
 416 static void dns_tcp_accept(struct stream_connection *conn)
 417 {
 418         struct dns_socket *dns_socket;
 419         struct dns_tcp_connection *dns_conn;
 420         struct tevent_req *subreq;
 421         int rc;
 422
 423         dns_conn = talloc_zero(conn, struct dns_tcp_connection);
 424         if (dns_conn == NULL) {
 425                 stream_terminate_connection(conn,
 426                                 "dns_tcp_accept: out of memory");
 427                 return;
 428         }
 429
 430         dns_conn->send_queue = tevent_queue_create(conn, "dns_tcp_accept");
 431         if (dns_conn->send_queue == NULL) {
 432                 stream_terminate_connection(conn,
 433                                 "dns_tcp_accept: out of memory");
 434                 return;
 435         }
 436
 437         dns_socket = talloc_get_type(conn->private_data, struct dns_socket);
 438
 439         TALLOC_FREE(conn->event.fde);
 440
 441         rc = tstream_bsd_existing_socket(dns_conn,
 442                         socket_get_fd(conn->socket),
 443                         &dns_conn->tstream);
 444         if (rc < 0) {
 445                 stream_terminate_connection(conn,
 446                                 "dns_tcp_accept: out of memory");
 447                 return;
 448         }
 449
 450         dns_conn->conn = conn;
 451         dns_conn->dns_socket = dns_socket;
 452         conn->private_data = dns_conn;
 453
 454         /*
 455          * The dns tcp pdu's has the length as 2 byte (initial_read_size),
 456          * packet_full_request_u16 provides the pdu length then.
 457          */
 458         subreq = tstream_read_pdu_blob_send(dns_conn,
 459                                             dns_conn->conn->event.ctx,
 460                                             dns_conn->tstream,
 461                                             2, /* initial_read_size */
 462                                             packet_full_request_u16,
 463                                             dns_conn);
 464         if (subreq == NULL) {
 465                 dns_tcp_terminate_connection(dns_conn, "dns_tcp_accept: "
 466                                 "no memory for tstream_read_pdu_blob_send");
 467                 return;
 468         }
 469         tevent_req_set_callback(subreq, dns_tcp_call_loop, dns_conn);
 470 }
 471
 472 static const struct stream_server_ops dns_tcp_stream_ops = {
 473         .name                   = "dns_tcp",
 474         .accept_connection      = dns_tcp_accept,
 475         .recv_handler           = dns_tcp_recv,
 476         .send_handler           = dns_tcp_send
 477 };
 478
 479 struct dns_udp_call {
 480         struct dns_udp_socket *sock;
 481         struct tsocket_address *src;
 482         DATA_BLOB in;
 483         DATA_BLOB out;
 484 };
 485
 486 static void dns_udp_call_process_done(struct tevent_req *subreq);
 487 static void dns_udp_call_sendto_done(struct tevent_req *subreq);
 488
 489 static void dns_udp_call_loop(struct tevent_req *subreq)
 490 {
 491         struct dns_udp_socket *sock = tevent_req_callback_data(subreq,
 492                                       struct dns_udp_socket);
 493         struct dns_server *dns = sock->dns_socket->dns;
 494         struct dns_udp_call *call;
 495         uint8_t *buf;
 496         ssize_t len;
 497         int sys_errno;
 498
 499         call = talloc(sock, struct dns_udp_call);
 500         if (call == NULL) {
 501                 talloc_free(call);
 502                 goto done;
 503         }
 504         call->sock = sock;
 505
 506         len = tdgram_recvfrom_recv(subreq, &sys_errno,
 507                                    call, &buf, &call->src);
 508         TALLOC_FREE(subreq);
 509         if (len == -1) {
 510                 talloc_free(call);
 511                 goto done;
 512         }
 513
 514         call->in.data = buf;
 515         call->in.length = len;
 516
 517         DEBUG(10,("Received DNS UDP packet of length %lu from %s\n",
 518                  (long)call->in.length,
 519                  tsocket_address_string(call->src, call)));
 520
 521         subreq = dns_process_send(call, dns->task->event_ctx, dns,
 522                                   &call->in);
 523         if (subreq == NULL) {
 524                 TALLOC_FREE(call);
 525                 goto done;
 526         }
 527         tevent_req_set_callback(subreq, dns_udp_call_process_done, call);
 528
 529 done:
 530         subreq = tdgram_recvfrom_send(sock,
 531                                       sock->dns_socket->dns->task->event_ctx,
 532                                       sock->dgram);
 533         if (subreq == NULL) {
 534                 task_server_terminate(sock->dns_socket->dns->task,
 535                                       "no memory for tdgram_recvfrom_send",
 536                                       true);
 537                 return;
 538         }
 539         tevent_req_set_callback(subreq, dns_udp_call_loop, sock);
 540 }
 541
 542 static void dns_udp_call_process_done(struct tevent_req *subreq)
 543 {
 544         struct dns_udp_call *call = tevent_req_callback_data(
 545                 subreq, struct dns_udp_call);
 546         struct dns_udp_socket *sock = call->sock;
 547         struct dns_server *dns = sock->dns_socket->dns;
 548         WERROR err;
 549
 550         err = dns_process_recv(subreq, call, &call->out);
 551         TALLOC_FREE(subreq);
 552         if (!W_ERROR_IS_OK(err)) {
 553                 DEBUG(1, ("dns_process returned %s\n", win_errstr(err)));
 554                 TALLOC_FREE(call);
 555                 return;
 556         }
 557
 558         subreq = tdgram_sendto_queue_send(call,
 559                                           dns->task->event_ctx,
 560                                           sock->dgram,
 561                                           sock->send_queue,
 562                                           call->out.data,
 563                                           call->out.length,
 564                                           call->src);
 565         if (subreq == NULL) {
 566                 talloc_free(call);
 567                 return;
 568         }
 569         tevent_req_set_callback(subreq, dns_udp_call_sendto_done, call);
 570
 571 }
 572 static void dns_udp_call_sendto_done(struct tevent_req *subreq)
 573 {
 574         struct dns_udp_call *call = tevent_req_callback_data(subreq,
 575                                        struct dns_udp_call);
 576         int sys_errno;
 577
 578         tdgram_sendto_queue_recv(subreq, &sys_errno);
 579
 580         /* We don't care about errors */
 581
 582         talloc_free(call);
 583 }
 584
 585 /*
 586   start listening on the given address
 587 */
 588 static NTSTATUS dns_add_socket(struct dns_server *dns,
 589                                const struct model_ops *model_ops,
 590                                const char *name,
 591                                const char *address,
 592                                uint16_t port)
 593 {
 594         struct dns_socket *dns_socket;
 595         struct dns_udp_socket *dns_udp_socket;
 596         struct tevent_req *udpsubreq;
 597         NTSTATUS status;
 598         int ret;
 599
 600         dns_socket = talloc(dns, struct dns_socket);
 601         NT_STATUS_HAVE_NO_MEMORY(dns_socket);
 602
 603         dns_socket->dns = dns;
 604
 605         ret = tsocket_address_inet_from_strings(dns_socket, "ip",
 606                                                 address, port,
 607                                                 &dns_socket->local_address);
 608         if (ret != 0) {
 609                 status = map_nt_error_from_unix_common(errno);
 610                 return status;
 611         }
 612
 613         status = stream_setup_socket(dns->task,
 614                                      dns->task->event_ctx,
 615                                      dns->task->lp_ctx,
 616                                      model_ops,
 617                                      &dns_tcp_stream_ops,
 618                                      "ip", address, &port,
 619                                      lpcfg_socket_options(dns->task->lp_ctx),
 620                                      dns_socket);
 621         if (!NT_STATUS_IS_OK(status)) {
 622                 DEBUG(0,("Failed to bind to %s:%u TCP - %s\n",
 623                          address, port, nt_errstr(status)));
 624                 talloc_free(dns_socket);
 625                 return status;
 626         }
 627
 628         dns_udp_socket = talloc(dns_socket, struct dns_udp_socket);
 629         NT_STATUS_HAVE_NO_MEMORY(dns_udp_socket);
 630
 631         dns_udp_socket->dns_socket = dns_socket;
 632
 633         ret = tdgram_inet_udp_socket(dns_socket->local_address,
 634                                      NULL,
 635                                      dns_udp_socket,
 636                                      &dns_udp_socket->dgram);
 637         if (ret != 0) {
 638                 status = map_nt_error_from_unix_common(errno);
 639                 DEBUG(0,("Failed to bind to %s:%u UDP - %s\n",
 640                          address, port, nt_errstr(status)));
 641                 return status;
 642         }
 643
 644         dns_udp_socket->send_queue = tevent_queue_create(dns_udp_socket,
 645                                                          "dns_udp_send_queue");
 646         NT_STATUS_HAVE_NO_MEMORY(dns_udp_socket->send_queue);
 647
 648         udpsubreq = tdgram_recvfrom_send(dns_udp_socket,
 649                                          dns->task->event_ctx,
 650                                          dns_udp_socket->dgram);
 651         NT_STATUS_HAVE_NO_MEMORY(udpsubreq);
 652         tevent_req_set_callback(udpsubreq, dns_udp_call_loop, dns_udp_socket);
 653
 654         return NT_STATUS_OK;
 655 }
 656
 657 /*
 658   setup our listening sockets on the configured network interfaces
 659 */
 660 static NTSTATUS dns_startup_interfaces(struct dns_server *dns, struct loadparm_context *lp_ctx,
 661                                        struct interface *ifaces)
 662 {
 663         const struct model_ops *model_ops;
 664         int num_interfaces;
 665         TALLOC_CTX *tmp_ctx = talloc_new(dns);
 666         NTSTATUS status;
 667         int i;
 668
 669         /* within the dns task we want to be a single process, so
 670            ask for the single process model ops and pass these to the
 671            stream_setup_socket() call. */
 672         model_ops = process_model_startup("single");
 673         if (!model_ops) {
 674                 DEBUG(0,("Can't find 'single' process model_ops\n"));
 675                 return NT_STATUS_INTERNAL_ERROR;
 676         }
 677
 678         if (ifaces != NULL) {
 679                 num_interfaces = iface_list_count(ifaces);
 680
 681                 for (i=0; i<num_interfaces; i++) {
 682                         const char *address = talloc_strdup(tmp_ctx,
 683                                                             iface_list_n_ip(ifaces, i));
 684
 685                         status = dns_add_socket(dns, model_ops, "dns", address,
 686                                                 DNS_SERVICE_PORT);
 687                         NT_STATUS_NOT_OK_RETURN(status);
 688                 }
 689         } else {
 690                 const char **wcard;
 691                 wcard = iface_list_wildcard(tmp_ctx, lp_ctx);
 692                 if (wcard == NULL) {
 693                         DEBUG(0, ("No wildcard address available\n"));
 694                         return NT_STATUS_INTERNAL_ERROR;
 695                 }
 696                 for (i = 0; wcard[i] != NULL; i++) {
 697                         status = dns_add_socket(dns, model_ops, "dns", wcard[i],
 698                                                 DNS_SERVICE_PORT);
 699                         NT_STATUS_NOT_OK_RETURN(status);
 700                 }
 701         }
 702
 703         talloc_free(tmp_ctx);
 704
 705         return NT_STATUS_OK;
 706 }
 707
 708 static int dns_server_sort_zones(struct ldb_message **m1, struct ldb_message **m2)
 709 {
 710         const char *n1, *n2;
 711         size_t l1, l2;
 712
 713         n1 = ldb_msg_find_attr_as_string(*m1, "name", NULL);
 714         n2 = ldb_msg_find_attr_as_string(*m2, "name", NULL);
 715
 716         l1 = strlen(n1);
 717         l2 = strlen(n2);
 718
 719         /* If the string lengths are not equal just sort by length */
 720         if (l1 != l2) {
 721                 /* If m1 is the larger zone name, return it first */
 722                 return l2 - l1;
 723         }
 724
 725         /*TODO: We need to compare DNs here, we want the DomainDNSZones first */
 726         return 0;
 727 }
 728
 729 static struct dns_server_tkey_store *tkey_store_init(TALLOC_CTX *mem_ctx,
 730                                                      uint16_t size)
 731 {
 732         struct dns_server_tkey_store *buffer = talloc_zero(mem_ctx,
 733                                                 struct dns_server_tkey_store);
 734
 735         if (buffer == NULL) {
 736                 return NULL;
 737         }
 738
 739         buffer->size = size;
 740         buffer->next_idx = 0;
 741
 742         buffer->tkeys = talloc_zero_array(buffer, struct dns_server_tkey *, size);
 743         if (buffer->tkeys == NULL) {
 744                 TALLOC_FREE(buffer);
 745         }
 746
 747         return buffer;
 748 }
 749
 750 static void dns_task_init(struct task_server *task)
 751 {
 752         struct dns_server *dns;
 753         NTSTATUS status;
 754         struct interface *ifaces = NULL;
 755         int ret;
 756         struct ldb_result *res;
 757         static const char * const attrs[] = { "name", NULL};
 758         static const char * const attrs_none[] = { NULL};
 759         unsigned int i;
 760         struct ldb_message *dns_acc;
 761         char *hostname_lower;
 762         char *dns_spn;
 763
 764         switch (lpcfg_server_role(task->lp_ctx)) {
 765         case ROLE_STANDALONE:
 766                 task_server_terminate(task, "dns: no DNS required in standalone configuration", false);
 767                 return;
 768         case ROLE_DOMAIN_MEMBER:
 769                 task_server_terminate(task, "dns: no DNS required in member server configuration", false);
 770                 return;
 771         case ROLE_ACTIVE_DIRECTORY_DC:
 772                 /* Yes, we want a DNS */
 773                 break;
 774         }
 775
 776         if (lpcfg_interfaces(task->lp_ctx) && lpcfg_bind_interfaces_only(task->lp_ctx)) {
 777                 load_interface_list(task, task->lp_ctx, &ifaces);
 778
 779                 if (iface_list_count(ifaces) == 0) {
 780                         task_server_terminate(task, "dns: no network interfaces configured", false);
 781                         return;
 782                 }
 783         }
 784
 785         task_server_set_title(task, "task[dns]");
 786
 787         dns = talloc_zero(task, struct dns_server);
 788         if (dns == NULL) {
 789                 task_server_terminate(task, "dns: out of memory", true);
 790                 return;
 791         }
 792
 793         dns->task = task;
 794         /*FIXME: Make this a configurable option */
 795         dns->max_payload = 4096;
 796
 797         dns->server_credentials = cli_credentials_init(dns);
 798         if (!dns->server_credentials) {
 799                 task_server_terminate(task, "Failed to init server credentials\n", true);
 800                 return;
 801         }
 802
 803         dns->samdb = samdb_connect(dns, dns->task->event_ctx, dns->task->lp_ctx,
 804                               system_session(dns->task->lp_ctx), 0);
 805         if (!dns->samdb) {
 806                 task_server_terminate(task, "dns: samdb_connect failed", true);
 807                 return;
 808         }
 809
 810         cli_credentials_set_conf(dns->server_credentials, task->lp_ctx);
 811
 812         hostname_lower = strlower_talloc(dns, lpcfg_netbios_name(task->lp_ctx));
 813         dns_spn = talloc_asprintf(dns, "DNS/%s.%s",
 814                                   hostname_lower,
 815                                   lpcfg_dnsdomain(task->lp_ctx));
 816         TALLOC_FREE(hostname_lower);
 817
 818         ret = dsdb_search_one(dns->samdb, dns, &dns_acc,
 819                               ldb_get_default_basedn(dns->samdb), LDB_SCOPE_SUBTREE,
 820                               attrs_none, 0, "(servicePrincipalName=%s)",
 821                               dns_spn);
 822         if (ret == LDB_SUCCESS) {
 823                 TALLOC_FREE(dns_acc);
 824                 if (!dns_spn) {
 825                         task_server_terminate(task, "dns: talloc_asprintf failed", true);
 826                         return;
 827                 }
 828                 status = cli_credentials_set_stored_principal(dns->server_credentials, task->lp_ctx, dns_spn);
 829                 if (!NT_STATUS_IS_OK(status)) {
 830                         task_server_terminate(task,
 831                                               talloc_asprintf(task, "Failed to obtain server credentials for DNS, "
 832                                                               "despite finding it in the samdb! %s\n",
 833                                                               nt_errstr(status)),
 834                                               true);
 835                         return;
 836                 }
 837         } else {
 838                 TALLOC_FREE(dns_spn);
 839                 status = cli_credentials_set_machine_account(dns->server_credentials, task->lp_ctx);
 840                 if (!NT_STATUS_IS_OK(status)) {
 841                         task_server_terminate(task,
 842                                               talloc_asprintf(task, "Failed to obtain server credentials, perhaps a standalone server?: %s\n",
 843                                                               nt_errstr(status)),
 844                                               true);
 845                         return;
 846                 }
 847         }
 848
 849         dns->tkeys = tkey_store_init(dns, TKEY_BUFFER_SIZE);
 850         if (!dns->tkeys) {
 851                 task_server_terminate(task, "Failed to allocate tkey storage\n", true);
 852                 return;
 853         }
 854
 855         // TODO: this search does not work against windows
 856         ret = dsdb_search(dns->samdb, dns, &res, NULL, LDB_SCOPE_SUBTREE,
 857                           attrs, DSDB_SEARCH_SEARCH_ALL_PARTITIONS, "(objectClass=dnsZone)");
 858         if (ret != LDB_SUCCESS) {
 859                 task_server_terminate(task,
 860                                       "dns: failed to look up root DNS zones",
 861                                       true);
 862                 return;
 863         }
 864
 865         TYPESAFE_QSORT(res->msgs, res->count, dns_server_sort_zones);
 866
 867         for (i=0; i < res->count; i++) {
 868                 struct dns_server_zone *z;
 869
 870                 z = talloc_zero(dns, struct dns_server_zone);
 871                 if (z == NULL) {
 872                         task_server_terminate(task, "dns failed to allocate memory", true);
 873                 }
 874
 875                 z->name = ldb_msg_find_attr_as_string(res->msgs[i], "name", NULL);
 876                 z->dn = talloc_move(z, &res->msgs[i]->dn);
 877                 /*
 878                  * Ignore the RootDNSServers zone and zones that we don't support yet
 879                  * RootDNSServers should never be returned (Windows DNS server don't)
 880                  * ..TrustAnchors should never be returned as is, (Windows returns
 881                  * TrustAnchors) and for the moment we don't support DNSSEC so we'd better
 882                  * not return this zone.
 883                  */
 884                 if ((strcmp(z->name, "RootDNSServers") == 0) ||
 885                     (strcmp(z->name, "..TrustAnchors") == 0))
 886                 {
 887                         DEBUG(10, ("Ignoring zone %s\n", z->name));
 888                         talloc_free(z);
 889                         continue;
 890                 }
 891                 DLIST_ADD_END(dns->zones, z, NULL);
 892         }
 893
 894         status = dns_startup_interfaces(dns, task->lp_ctx, ifaces);
 895         if (!NT_STATUS_IS_OK(status)) {
 896                 task_server_terminate(task, "dns failed to setup interfaces", true);
 897                 return;
 898         }
 899 }
 900
 901 NTSTATUS server_service_dns_init(void)
 902 {
 903         return register_server_service("dns", dns_task_init);
 904 }