contrib/bind/lib/dns/include/dns/resolver.h

   1 /*
   2  * Copyright (C) 2004-2010  Internet Systems Consortium, Inc. ("ISC")
   3  * Copyright (C) 1999-2001, 2003  Internet Software Consortium.
   4  *
   5  * Permission to use, copy, modify, and/or distribute this software for any
   6  * purpose with or without fee is hereby granted, provided that the above
   7  * copyright notice and this permission notice appear in all copies.
   8  *
   9  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
  10  * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
  11  * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
  12  * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
  13  * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
  14  * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
  15  * PERFORMANCE OF THIS SOFTWARE.
  16  */
  17
  18 /* $Id: resolver.h,v 1.56.128.7.2.2 2010/02/25 10:56:02 tbox Exp $ */
  19
  20 #ifndef DNS_RESOLVER_H
  21 #define DNS_RESOLVER_H 1
  22
  23 /*****
  24  ***** Module Info
  25  *****/
  26
  27 /*! \file dns/resolver.h
  28  *
  29  * \brief
  30  * This is the BIND 9 resolver, the module responsible for resolving DNS
  31  * requests by iteratively querying authoritative servers and following
  32  * referrals.  This is a "full resolver", not to be confused with
  33  * the stub resolvers most people associate with the word "resolver".
  34  * The full resolver is part of the caching name server or resolver
  35  * daemon the stub resolver talks to.
  36  *
  37  * MP:
  38  *\li   The module ensures appropriate synchronization of data structures it
  39  *      creates and manipulates.
  40  *
  41  * Reliability:
  42  *\li   No anticipated impact.
  43  *
  44  * Resources:
  45  *\li   TBS
  46  *
  47  * Security:
  48  *\li   No anticipated impact.
  49  *
  50  * Standards:
  51  *\li   RFCs:   1034, 1035, 2181, TBS
  52  *\li   Drafts: TBS
  53  */
  54
  55 #include <isc/lang.h>
  56 #include <isc/socket.h>
  57
  58 #include <dns/types.h>
  59 #include <dns/fixedname.h>
  60
  61 ISC_LANG_BEGINDECLS
  62
  63 /*%
  64  * A dns_fetchevent_t is sent when a 'fetch' completes.  Any of 'db',
  65  * 'node', 'rdataset', and 'sigrdataset' may be bound.  It is the
  66  * receiver's responsibility to detach before freeing the event.
  67  * \brief
  68  * 'rdataset', 'sigrdataset', 'client' and 'id' are the values that were
  69  * supplied when dns_resolver_createfetch() was called.  They are returned
  70  *  to the caller so that they may be freed.
  71  */
  72 typedef struct dns_fetchevent {
  73         ISC_EVENT_COMMON(struct dns_fetchevent);
  74         dns_fetch_t *                   fetch;
  75         isc_result_t                    result;
  76         dns_rdatatype_t                 qtype;
  77         dns_db_t *                      db;
  78         dns_dbnode_t *                  node;
  79         dns_rdataset_t *                rdataset;
  80         dns_rdataset_t *                sigrdataset;
  81         dns_fixedname_t                 foundname;
  82         isc_sockaddr_t *                client;
  83         dns_messageid_t                 id;
  84 } dns_fetchevent_t;
  85
  86 /*
  87  * Options that modify how a 'fetch' is done.
  88  */
  89 #define DNS_FETCHOPT_TCP                0x01         /*%< Use TCP. */
  90 #define DNS_FETCHOPT_UNSHARED           0x02         /*%< See below. */
  91 #define DNS_FETCHOPT_RECURSIVE          0x04         /*%< Set RD? */
  92 #define DNS_FETCHOPT_NOEDNS0            0x08         /*%< Do not use EDNS. */
  93 #define DNS_FETCHOPT_FORWARDONLY        0x10         /*%< Only use forwarders. */
  94 #define DNS_FETCHOPT_NOVALIDATE         0x20         /*%< Disable validation. */
  95 #define DNS_FETCHOPT_EDNS512            0x40         /*%< Advertise a 512 byte
  96                                                           UDP buffer. */
  97 #define DNS_FETCHOPT_WANTNSID           0x80         /*%< Request NSID */
  98
  99 #define DNS_FETCHOPT_EDNSVERSIONSET     0x00800000
 100 #define DNS_FETCHOPT_EDNSVERSIONMASK    0xff000000
 101 #define DNS_FETCHOPT_EDNSVERSIONSHIFT   24
 102
 103 /*
 104  * Upper bounds of class of query RTT (ms).  Corresponds to
 105  * dns_resstatscounter_queryrttX statistics counters.
 106  */
 107 #define DNS_RESOLVER_QRYRTTCLASS0       10
 108 #define DNS_RESOLVER_QRYRTTCLASS0STR    "10"
 109 #define DNS_RESOLVER_QRYRTTCLASS1       100
 110 #define DNS_RESOLVER_QRYRTTCLASS1STR    "100"
 111 #define DNS_RESOLVER_QRYRTTCLASS2       500
 112 #define DNS_RESOLVER_QRYRTTCLASS2STR    "500"
 113 #define DNS_RESOLVER_QRYRTTCLASS3       800
 114 #define DNS_RESOLVER_QRYRTTCLASS3STR    "800"
 115 #define DNS_RESOLVER_QRYRTTCLASS4       1600
 116 #define DNS_RESOLVER_QRYRTTCLASS4STR    "1600"
 117
 118 /*
 119  * XXXRTH  Should this API be made semi-private?  (I.e.
 120  * _dns_resolver_create()).
 121  */
 122
 123 #define DNS_RESOLVER_CHECKNAMES         0x01
 124 #define DNS_RESOLVER_CHECKNAMESFAIL     0x02
 125
 126 isc_result_t
 127 dns_resolver_create(dns_view_t *view,
 128                     isc_taskmgr_t *taskmgr, unsigned int ntasks,
 129                     isc_socketmgr_t *socketmgr,
 130                     isc_timermgr_t *timermgr,
 131                     unsigned int options,
 132                     dns_dispatchmgr_t *dispatchmgr,
 133                     dns_dispatch_t *dispatchv4,
 134                     dns_dispatch_t *dispatchv6,
 135                     dns_resolver_t **resp);
 136
 137 /*%<
 138  * Create a resolver.
 139  *
 140  * Notes:
 141  *
 142  *\li   Generally, applications should not create a resolver directly, but
 143  *      should instead call dns_view_createresolver().
 144  *
 145  * Requires:
 146  *
 147  *\li   'view' is a valid view.
 148  *
 149  *\li   'taskmgr' is a valid task manager.
 150  *
 151  *\li   'ntasks' > 0.
 152  *
 153  *\li   'socketmgr' is a valid socket manager.
 154  *
 155  *\li   'timermgr' is a valid timer manager.
 156  *
 157  *\li   'dispatchv4' is a valid dispatcher with an IPv4 UDP socket, or is NULL.
 158  *
 159  *\li   'dispatchv6' is a valid dispatcher with an IPv6 UDP socket, or is NULL.
 160  *
 161  *\li   resp != NULL && *resp == NULL.
 162  *
 163  * Returns:
 164  *
 165  *\li   #ISC_R_SUCCESS                          On success.
 166  *
 167  *\li   Anything else                           Failure.
 168  */
 169
 170 void
 171 dns_resolver_freeze(dns_resolver_t *res);
 172 /*%<
 173  * Freeze resolver.
 174  *
 175  * Notes:
 176  *
 177  *\li   Certain configuration changes cannot be made after the resolver
 178  *      is frozen.  Fetches cannot be created until the resolver is frozen.
 179  *
 180  * Requires:
 181  *
 182  *\li   'res' is a valid, unfrozen resolver.
 183  *
 184  * Ensures:
 185  *
 186  *\li   'res' is frozen.
 187  */
 188
 189 void
 190 dns_resolver_prime(dns_resolver_t *res);
 191 /*%<
 192  * Prime resolver.
 193  *
 194  * Notes:
 195  *
 196  *\li   Resolvers which have a forwarding policy other than dns_fwdpolicy_only
 197  *      need to be primed with the root nameservers, otherwise the root
 198  *      nameserver hints data may be used indefinitely.  This function requests
 199  *      that the resolver start a priming fetch, if it isn't already priming.
 200  *
 201  * Requires:
 202  *
 203  *\li   'res' is a valid, frozen resolver.
 204  */
 205
 206
 207 void
 208 dns_resolver_whenshutdown(dns_resolver_t *res, isc_task_t *task,
 209                           isc_event_t **eventp);
 210 /*%<
 211  * Send '*eventp' to 'task' when 'res' has completed shutdown.
 212  *
 213  * Notes:
 214  *
 215  *\li   It is not safe to detach the last reference to 'res' until
 216  *      shutdown is complete.
 217  *
 218  * Requires:
 219  *
 220  *\li   'res' is a valid resolver.
 221  *
 222  *\li   'task' is a valid task.
 223  *
 224  *\li   *eventp is a valid event.
 225  *
 226  * Ensures:
 227  *
 228  *\li   *eventp == NULL.
 229  */
 230
 231 void
 232 dns_resolver_shutdown(dns_resolver_t *res);
 233 /*%<
 234  * Start the shutdown process for 'res'.
 235  *
 236  * Notes:
 237  *
 238  *\li   This call has no effect if the resolver is already shutting down.
 239  *
 240  * Requires:
 241  *
 242  *\li   'res' is a valid resolver.
 243  */
 244
 245 void
 246 dns_resolver_attach(dns_resolver_t *source, dns_resolver_t **targetp);
 247
 248 void
 249 dns_resolver_detach(dns_resolver_t **resp);
 250
 251 isc_result_t
 252 dns_resolver_createfetch(dns_resolver_t *res, dns_name_t *name,
 253                          dns_rdatatype_t type,
 254                          dns_name_t *domain, dns_rdataset_t *nameservers,
 255                          dns_forwarders_t *forwarders,
 256                          unsigned int options, isc_task_t *task,
 257                          isc_taskaction_t action, void *arg,
 258                          dns_rdataset_t *rdataset,
 259                          dns_rdataset_t *sigrdataset,
 260                          dns_fetch_t **fetchp);
 261
 262 isc_result_t
 263 dns_resolver_createfetch2(dns_resolver_t *res, dns_name_t *name,
 264                           dns_rdatatype_t type,
 265                           dns_name_t *domain, dns_rdataset_t *nameservers,
 266                           dns_forwarders_t *forwarders,
 267                           isc_sockaddr_t *client, isc_uint16_t id,
 268                           unsigned int options, isc_task_t *task,
 269                           isc_taskaction_t action, void *arg,
 270                           dns_rdataset_t *rdataset,
 271                           dns_rdataset_t *sigrdataset,
 272                           dns_fetch_t **fetchp);
 273 /*%<
 274  * Recurse to answer a question.
 275  *
 276  * Notes:
 277  *
 278  *\li   This call starts a query for 'name', type 'type'.
 279  *
 280  *\li   The 'domain' is a parent domain of 'name' for which
 281  *      a set of name servers 'nameservers' is known.  If no
 282  *      such name server information is available, set
 283  *      'domain' and 'nameservers' to NULL.
 284  *
 285  *\li   'forwarders' is unimplemented, and subject to change when
 286  *      we figure out how selective forwarding will work.
 287  *
 288  *\li   When the fetch completes (successfully or otherwise), a
 289  *      #DNS_EVENT_FETCHDONE event with action 'action' and arg 'arg' will be
 290  *      posted to 'task'.
 291  *
 292  *\li   The values of 'rdataset' and 'sigrdataset' will be returned in
 293  *      the FETCHDONE event.
 294  *
 295  *\li   'client' and 'id' are used for duplicate query detection.  '*client'
 296  *      must remain stable until after 'action' has been called or
 297  *      dns_resolver_cancelfetch() is called.
 298  *
 299  * Requires:
 300  *
 301  *\li   'res' is a valid resolver that has been frozen.
 302  *
 303  *\li   'name' is a valid name.
 304  *
 305  *\li   'type' is not a meta type other than ANY.
 306  *
 307  *\li   'domain' is a valid name or NULL.
 308  *
 309  *\li   'nameservers' is a valid NS rdataset (whose owner name is 'domain')
 310  *      iff. 'domain' is not NULL.
 311  *
 312  *\li   'forwarders' is NULL.
 313  *
 314  *\li   'client' is a valid sockaddr or NULL.
 315  *
 316  *\li   'options' contains valid options.
 317  *
 318  *\li   'rdataset' is a valid, disassociated rdataset.
 319  *
 320  *\li   'sigrdataset' is NULL, or is a valid, disassociated rdataset.
 321  *
 322  *\li   fetchp != NULL && *fetchp == NULL.
 323  *
 324  * Returns:
 325  *
 326  *\li   #ISC_R_SUCCESS                                  Success
 327  *\li   #DNS_R_DUPLICATE
 328  *\li   #DNS_R_DROP
 329  *
 330  *\li   Many other values are possible, all of which indicate failure.
 331  */
 332
 333 void
 334 dns_resolver_cancelfetch(dns_fetch_t *fetch);
 335 /*%<
 336  * Cancel 'fetch'.
 337  *
 338  * Notes:
 339  *
 340  *\li   If 'fetch' has not completed, post its FETCHDONE event with a
 341  *      result code of #ISC_R_CANCELED.
 342  *
 343  * Requires:
 344  *
 345  *\li   'fetch' is a valid fetch.
 346  */
 347
 348 void
 349 dns_resolver_destroyfetch(dns_fetch_t **fetchp);
 350 /*%<
 351  * Destroy 'fetch'.
 352  *
 353  * Requires:
 354  *
 355  *\li   '*fetchp' is a valid fetch.
 356  *
 357  *\li   The caller has received the FETCHDONE event (either because the
 358  *      fetch completed or because dns_resolver_cancelfetch() was called).
 359  *
 360  * Ensures:
 361  *
 362  *\li   *fetchp == NULL.
 363  */
 364
 365 void
 366 dns_resolver_logfetch(dns_fetch_t *fetch, isc_log_t *lctx,
 367                       isc_logcategory_t *category, isc_logmodule_t *module,
 368                       int level, isc_boolean_t duplicateok);
 369 /*%<
 370  * Dump a log message on internal state at the completion of given 'fetch'.
 371  * 'lctx', 'category', 'module', and 'level' are used to write the log message.
 372  * By default, only one log message is written even if the corresponding fetch
 373  * context serves multiple clients; if 'duplicateok' is true the suppression
 374  * is disabled and the message can be written every time this function is
 375  * called.
 376  *
 377  * Requires:
 378  *
 379  *\li   'fetch' is a valid fetch, and has completed.
 380  */
 381
 382 dns_dispatchmgr_t *
 383 dns_resolver_dispatchmgr(dns_resolver_t *resolver);
 384
 385 dns_dispatch_t *
 386 dns_resolver_dispatchv4(dns_resolver_t *resolver);
 387
 388 dns_dispatch_t *
 389 dns_resolver_dispatchv6(dns_resolver_t *resolver);
 390
 391 isc_socketmgr_t *
 392 dns_resolver_socketmgr(dns_resolver_t *resolver);
 393
 394 isc_taskmgr_t *
 395 dns_resolver_taskmgr(dns_resolver_t *resolver);
 396
 397 isc_uint32_t
 398 dns_resolver_getlamettl(dns_resolver_t *resolver);
 399 /*%<
 400  * Get the resolver's lame-ttl.  zero => no lame processing.
 401  *
 402  * Requires:
 403  *\li   'resolver' to be valid.
 404  */
 405
 406 void
 407 dns_resolver_setlamettl(dns_resolver_t *resolver, isc_uint32_t lame_ttl);
 408 /*%<
 409  * Set the resolver's lame-ttl.  zero => no lame processing.
 410  *
 411  * Requires:
 412  *\li   'resolver' to be valid.
 413  */
 414
 415 unsigned int
 416 dns_resolver_nrunning(dns_resolver_t *resolver);
 417 /*%<
 418  * Return the number of currently running resolutions in this
 419  * resolver.  This is may be less than the number of outstanding
 420  * fetches due to multiple identical fetches, or more than the
 421  * number of of outstanding fetches due to the fact that resolution
 422  * can continue even though a fetch has been canceled.
 423  */
 424
 425 isc_result_t
 426 dns_resolver_addalternate(dns_resolver_t *resolver, isc_sockaddr_t *alt,
 427                           dns_name_t *name, in_port_t port);
 428 /*%<
 429  * Add alternate addresses to be tried in the event that the nameservers
 430  * for a zone are not available in the address families supported by the
 431  * operating system.
 432  *
 433  * Require:
 434  * \li  only one of 'name' or 'alt' to be valid.
 435  */
 436
 437 void
 438 dns_resolver_setudpsize(dns_resolver_t *resolver, isc_uint16_t udpsize);
 439 /*%<
 440  * Set the EDNS UDP buffer size advertised by the server.
 441  */
 442
 443 isc_uint16_t
 444 dns_resolver_getudpsize(dns_resolver_t *resolver);
 445 /*%<
 446  * Get the current EDNS UDP buffer size.
 447  */
 448
 449 void
 450 dns_resolver_reset_algorithms(dns_resolver_t *resolver);
 451 /*%<
 452  * Clear the disabled DNSSEC algorithms.
 453  */
 454
 455 isc_result_t
 456 dns_resolver_disable_algorithm(dns_resolver_t *resolver, dns_name_t *name,
 457                                unsigned int alg);
 458 /*%<
 459  * Mark the give DNSSEC algorithm as disabled and below 'name'.
 460  * Valid algorithms are less than 256.
 461  *
 462  * Returns:
 463  *\li   #ISC_R_SUCCESS
 464  *\li   #ISC_R_RANGE
 465  *\li   #ISC_R_NOMEMORY
 466  */
 467
 468 isc_boolean_t
 469 dns_resolver_algorithm_supported(dns_resolver_t *resolver, dns_name_t *name,
 470                                  unsigned int alg);
 471 /*%<
 472  * Check if the given algorithm is supported by this resolver.
 473  * This checks if the algorithm has been disabled via
 474  * dns_resolver_disable_algorithm() then the underlying
 475  * crypto libraries if not specifically disabled.
 476  */
 477
 478 isc_boolean_t
 479 dns_resolver_digest_supported(dns_resolver_t *resolver, unsigned int digest_type);
 480 /*%<
 481  * Is this digest type supported.
 482  */
 483
 484 void
 485 dns_resolver_resetmustbesecure(dns_resolver_t *resolver);
 486
 487 isc_result_t
 488 dns_resolver_setmustbesecure(dns_resolver_t *resolver, dns_name_t *name,
 489                              isc_boolean_t value);
 490
 491 isc_boolean_t
 492 dns_resolver_getmustbesecure(dns_resolver_t *resolver, dns_name_t *name);
 493
 494 void
 495 dns_resolver_setclientsperquery(dns_resolver_t *resolver,
 496                                 isc_uint32_t min, isc_uint32_t max);
 497
 498 void
 499 dns_resolver_getclientsperquery(dns_resolver_t *resolver, isc_uint32_t *cur,
 500                                 isc_uint32_t *min, isc_uint32_t *max);
 501
 502 isc_boolean_t
 503 dns_resolver_getzeronosoattl(dns_resolver_t *resolver);
 504
 505 void
 506 dns_resolver_setzeronosoattl(dns_resolver_t *resolver, isc_boolean_t state);
 507
 508 unsigned int
 509 dns_resolver_getoptions(dns_resolver_t *resolver);
 510
 511 void
 512 dns_resolver_addbadcache(dns_resolver_t *resolver, dns_name_t *name,
 513                          dns_rdatatype_t type, isc_time_t *expire);
 514 /*%<
 515  * Add a entry to the bad cache for <name,type> that will expire at 'expire'.
 516  *
 517  * Requires:
 518  * \li  resolver to be valid.
 519  * \li  name to be valid.
 520  */
 521
 522 isc_boolean_t
 523 dns_resolver_getbadcache(dns_resolver_t *resolver, dns_name_t *name,
 524                          dns_rdatatype_t type, isc_time_t *now);
 525 /*%<
 526  * Check to see if there is a unexpired entry in the bad cache for
 527  * <name,type>.
 528  *
 529  * Requires:
 530  * \li  resolver to be valid.
 531  * \li  name to be valid.
 532  */
 533
 534 void
 535 dns_resolver_flushbadcache(dns_resolver_t *resolver, dns_name_t *name);
 536 /*%<
 537  * Flush the bad cache of all entries at 'name' if 'name' is non NULL.
 538  * Flush the entire bad cache if 'name' is NULL.
 539  *
 540  * Requires:
 541  * \li  resolver to be valid.
 542  */
 543
 544 void
 545 dns_resolver_printbadcache(dns_resolver_t *resolver, FILE *fp);
 546 /*%
 547  * Print out the contents of the bad cache to 'fp'.
 548  *
 549  * Requires:
 550  * \li  resolver to be valid.
 551  */
 552
 553 ISC_LANG_ENDDECLS
 554
 555 #endif /* DNS_RESOLVER_H */