1/* 2 * Copyright (C) 2004-2008, 2011, 2012 Internet Systems Consortium, Inc. ("ISC") 3 * Copyright (C) 1999-2003 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/* $Id$ */ 19 20#ifndef DNS_ADB_H 21#define DNS_ADB_H 1 22 23/***** 24 ***** Module Info 25 *****/ 26 27/*! \file dns/adb.h 28 *\brief 29 * DNS Address Database 30 * 31 * This module implements an address database (ADB) for mapping a name 32 * to an isc_sockaddr_t. It also provides statistical information on 33 * how good that address might be. 34 * 35 * A client will pass in a dns_name_t, and the ADB will walk through 36 * the rdataset looking up addresses associated with the name. If it 37 * is found on the internal lists, a structure is filled in with the 38 * address information and stats for found addresses. 39 * 40 * If the name cannot be found on the internal lists, a new entry will 41 * be created for a name if all the information needed can be found 42 * in the zone table or cache. This new address will then be returned. 43 * 44 * If a request must be made to remote servers to satisfy a name lookup, 45 * this module will start fetches to try to complete these addresses. When 46 * at least one more completes, an event is sent to the caller. If none of 47 * them resolve before the fetch times out, an event indicating this is 48 * sent instead. 49 * 50 * Records are stored internally until a timer expires. The timer is the 51 * smaller of the TTL or signature validity period. 52 * 53 * Lameness is stored per <qname,qtype> tuple, and this data hangs off each 54 * address field. When an address is marked lame for a given tuple the address 55 * will not be returned to a caller. 56 * 57 * 58 * MP: 59 * 60 *\li The ADB takes care of all necessary locking. 61 * 62 *\li Only the task which initiated the name lookup can cancel the lookup. 63 * 64 * 65 * Security: 66 * 67 *\li None, since all data stored is required to be pre-filtered. 68 * (Cache needs to be sane, fetches return bounds-checked and sanity- 69 * checked data, caller passes a good dns_name_t for the zone, etc) 70 */ 71 72/*** 73 *** Imports 74 ***/ 75 76#include <isc/lang.h> 77#include <isc/magic.h> 78#include <isc/mem.h> 79#include <isc/sockaddr.h> 80 81#include <dns/types.h> 82#include <dns/view.h> 83 84ISC_LANG_BEGINDECLS 85 86/*** 87 *** Magic number checks 88 ***/ 89 90#define DNS_ADBFIND_MAGIC ISC_MAGIC('a','d','b','H') 91#define DNS_ADBFIND_VALID(x) ISC_MAGIC_VALID(x, DNS_ADBFIND_MAGIC) 92#define DNS_ADBADDRINFO_MAGIC ISC_MAGIC('a','d','A','I') 93#define DNS_ADBADDRINFO_VALID(x) ISC_MAGIC_VALID(x, DNS_ADBADDRINFO_MAGIC) 94 95 96/*** 97 *** TYPES 98 ***/ 99 100typedef struct dns_adbname dns_adbname_t; 101 102/*! 103 *\brief 104 * Represents a lookup for a single name. 105 * 106 * On return, the client can safely use "list", and can reorder the list. 107 * Items may not be _deleted_ from this list, however, or added to it 108 * other than by using the dns_adb_*() API. 109 */ 110struct dns_adbfind { 111 /* Public */ 112 unsigned int magic; /*%< RO: magic */ 113 dns_adbaddrinfolist_t list; /*%< RO: list of addrs */ 114 unsigned int query_pending; /*%< RO: partial list */ 115 unsigned int partial_result; /*%< RO: addrs missing */ 116 unsigned int options; /*%< RO: options */ 117 isc_result_t result_v4; /*%< RO: v4 result */ 118 isc_result_t result_v6; /*%< RO: v6 result */ 119 ISC_LINK(dns_adbfind_t) publink; /*%< RW: client use */ 120 121 /* Private */ 122 isc_mutex_t lock; /* locks all below */ 123 in_port_t port; 124 int name_bucket; 125 unsigned int flags; 126 dns_adbname_t *adbname; 127 dns_adb_t *adb; 128 isc_event_t event; 129 ISC_LINK(dns_adbfind_t) plink; 130}; 131 132/* 133 * _INET: 134 * _INET6: 135 * return addresses of that type. 136 * 137 * _EMPTYEVENT: 138 * Only schedule an event if no addresses are known. 139 * Must set _WANTEVENT for this to be meaningful. 140 * 141 * _WANTEVENT: 142 * An event is desired. Check this bit in the returned find to see 143 * if one will actually be generated. 144 * 145 * _AVOIDFETCHES: 146 * If set, fetches will not be generated unless no addresses are 147 * available in any of the address families requested. 148 * 149 * _STARTATZONE: 150 * Fetches will start using the closest zone data or use the root servers. 151 * This is useful for reestablishing glue that has expired. 152 * 153 * _GLUEOK: 154 * _HINTOK: 155 * Glue or hints are ok. These are used when matching names already 156 * in the adb, and when dns databases are searched. 157 * 158 * _RETURNLAME: 159 * Return lame servers in a find, so that all addresses are returned. 160 * 161 * _LAMEPRUNED: 162 * At least one address was omitted from the list because it was lame. 163 * This bit will NEVER be set if _RETURNLAME is set in the createfind(). 164 */ 165/*% Return addresses of type INET. */ 166#define DNS_ADBFIND_INET 0x00000001 167/*% Return addresses of type INET6. */ 168#define DNS_ADBFIND_INET6 0x00000002 169#define DNS_ADBFIND_ADDRESSMASK 0x00000003 170/*% 171 * Only schedule an event if no addresses are known. 172 * Must set _WANTEVENT for this to be meaningful. 173 */ 174#define DNS_ADBFIND_EMPTYEVENT 0x00000004 175/*% 176 * An event is desired. Check this bit in the returned find to see 177 * if one will actually be generated. 178 */ 179#define DNS_ADBFIND_WANTEVENT 0x00000008 180/*% 181 * If set, fetches will not be generated unless no addresses are 182 * available in any of the address families requested. 183 */ 184#define DNS_ADBFIND_AVOIDFETCHES 0x00000010 185/*% 186 * Fetches will start using the closest zone data or use the root servers. 187 * This is useful for reestablishing glue that has expired. 188 */ 189#define DNS_ADBFIND_STARTATZONE 0x00000020 190/*% 191 * Glue or hints are ok. These are used when matching names already 192 * in the adb, and when dns databases are searched. 193 */ 194#define DNS_ADBFIND_GLUEOK 0x00000040 195/*% 196 * Glue or hints are ok. These are used when matching names already 197 * in the adb, and when dns databases are searched. 198 */ 199#define DNS_ADBFIND_HINTOK 0x00000080 200/*% 201 * Return lame servers in a find, so that all addresses are returned. 202 */ 203#define DNS_ADBFIND_RETURNLAME 0x00000100 204/*% 205 * Only schedule an event if no addresses are known. 206 * Must set _WANTEVENT for this to be meaningful. 207 */ 208#define DNS_ADBFIND_LAMEPRUNED 0x00000200 209 210/*% 211 * The answers to queries come back as a list of these. 212 */ 213struct dns_adbaddrinfo { 214 unsigned int magic; /*%< private */ 215 216 isc_sockaddr_t sockaddr; /*%< [rw] */ 217 unsigned int srtt; /*%< [rw] microseconds */ 218 unsigned int flags; /*%< [rw] */ 219 dns_adbentry_t *entry; /*%< private */ 220 ISC_LINK(dns_adbaddrinfo_t) publink; 221}; 222 223/*!< 224 * The event sent to the caller task is just a plain old isc_event_t. It 225 * contains no data other than a simple status, passed in the "type" field 226 * to indicate that another address resolved, or all partially resolved 227 * addresses have failed to resolve. 228 * 229 * "sender" is the dns_adbfind_t used to issue this query. 230 * 231 * This is simply a standard event, with the "type" set to: 232 * 233 *\li #DNS_EVENT_ADBMOREADDRESSES -- another address resolved. 234 *\li #DNS_EVENT_ADBNOMOREADDRESSES -- all pending addresses failed, 235 * were canceled, or otherwise will 236 * not be usable. 237 *\li #DNS_EVENT_ADBCANCELED -- The request was canceled by a 238 * 3rd party. 239 *\li #DNS_EVENT_ADBNAMEDELETED -- The name was deleted, so this request 240 * was canceled. 241 * 242 * In each of these cases, the addresses returned by the initial call 243 * to dns_adb_createfind() can still be used until they are no longer needed. 244 */ 245 246/**** 247 **** FUNCTIONS 248 ****/ 249 250 251isc_result_t 252dns_adb_create(isc_mem_t *mem, dns_view_t *view, isc_timermgr_t *tmgr, 253 isc_taskmgr_t *taskmgr, dns_adb_t **newadb); 254/*%< 255 * Create a new ADB. 256 * 257 * Notes: 258 * 259 *\li Generally, applications should not create an ADB directly, but 260 * should instead call dns_view_createresolver(). 261 * 262 * Requires: 263 * 264 *\li 'mem' must be a valid memory context. 265 * 266 *\li 'view' be a pointer to a valid view. 267 * 268 *\li 'tmgr' be a pointer to a valid timer manager. 269 * 270 *\li 'taskmgr' be a pointer to a valid task manager. 271 * 272 *\li 'newadb' != NULL && '*newadb' == NULL. 273 * 274 * Returns: 275 * 276 *\li #ISC_R_SUCCESS after happiness. 277 *\li #ISC_R_NOMEMORY after resource allocation failure. 278 */ 279 280void 281dns_adb_attach(dns_adb_t *adb, dns_adb_t **adbp); 282/*% 283 * Attach to an 'adb' to 'adbp'. 284 * 285 * Requires: 286 *\li 'adb' to be a valid dns_adb_t, created via dns_adb_create(). 287 *\li 'adbp' to be a valid pointer to a *dns_adb_t which is initialized 288 * to NULL. 289 */ 290 291void 292dns_adb_detach(dns_adb_t **adb); 293/*% 294 * Delete the ADB. Sets *ADB to NULL. Cancels any outstanding requests. 295 * 296 * Requires: 297 * 298 *\li 'adb' be non-NULL and '*adb' be a valid dns_adb_t, created via 299 * dns_adb_create(). 300 */ 301 302void 303dns_adb_whenshutdown(dns_adb_t *adb, isc_task_t *task, isc_event_t **eventp); 304/*% 305 * Send '*eventp' to 'task' when 'adb' has shutdown. 306 * 307 * Requires: 308 * 309 *\li '*adb' is a valid dns_adb_t. 310 * 311 *\li eventp != NULL && *eventp is a valid event. 312 * 313 * Ensures: 314 * 315 *\li *eventp == NULL 316 * 317 *\li The event's sender field is set to the value of adb when the event 318 * is sent. 319 */ 320 321void 322dns_adb_shutdown(dns_adb_t *adb); 323/*%< 324 * Shutdown 'adb'. 325 * 326 * Requires: 327 * 328 * \li '*adb' is a valid dns_adb_t. 329 */ 330 331isc_result_t 332dns_adb_createfind(dns_adb_t *adb, isc_task_t *task, isc_taskaction_t action, 333 void *arg, dns_name_t *name, dns_name_t *qname, 334 dns_rdatatype_t qtype, unsigned int options, 335 isc_stdtime_t now, dns_name_t *target, 336 in_port_t port, dns_adbfind_t **find); 337/*%< 338 * Main interface for clients. The adb will look up the name given in 339 * "name" and will build up a list of found addresses, and perhaps start 340 * internal fetches to resolve names that are unknown currently. 341 * 342 * If other addresses resolve after this call completes, an event will 343 * be sent to the <task, taskaction, arg> with the sender of that event 344 * set to a pointer to the dns_adbfind_t returned by this function. 345 * 346 * If no events will be generated, the *find->result_v4 and/or result_v6 347 * members may be examined for address lookup status. The usual #ISC_R_SUCCESS, 348 * #ISC_R_FAILURE, #DNS_R_NXDOMAIN, and #DNS_R_NXRRSET are returned, along with 349 * #ISC_R_NOTFOUND meaning the ADB has not _yet_ found the values. In this 350 * latter case, retrying may produce more addresses. 351 * 352 * If events will be returned, the result_v[46] members are only valid 353 * when that event is actually returned. 354 * 355 * The list of addresses returned is unordered. The caller must impose 356 * any ordering required. The list will not contain "known bad" addresses, 357 * however. For instance, it will not return hosts that are known to be 358 * lame for the zone in question. 359 * 360 * The caller cannot (directly) modify the contents of the address list's 361 * fields other than the "link" field. All values can be read at any 362 * time, however. 363 * 364 * The "now" parameter is used only for determining which entries that 365 * have a specific time to live or expire time should be removed from 366 * the running database. If specified as zero, the current time will 367 * be retrieved and used. 368 * 369 * If 'target' is not NULL and 'name' is an alias (i.e. the name is 370 * CNAME'd or DNAME'd to another name), then 'target' will be updated with 371 * the domain name that 'name' is aliased to. 372 * 373 * All addresses returned will have the sockaddr's port set to 'port.' 374 * The caller may change them directly in the dns_adbaddrinfo_t since 375 * they are copies of the internal address only. 376 * 377 * XXXMLG Document options, especially the flags which control how 378 * events are sent. 379 * 380 * Requires: 381 * 382 *\li *adb be a valid isc_adb_t object. 383 * 384 *\li If events are to be sent, *task be a valid task, 385 * and isc_taskaction_t != NULL. 386 * 387 *\li *name is a valid dns_name_t. 388 * 389 *\li qname != NULL and *qname be a valid dns_name_t. 390 * 391 *\li target == NULL or target is a valid name with a buffer. 392 * 393 *\li find != NULL && *find == NULL. 394 * 395 * Returns: 396 * 397 *\li #ISC_R_SUCCESS Addresses might have been returned, and events will be 398 * delivered for unresolved addresses. 399 *\li #ISC_R_NOMORE Addresses might have been returned, but no events 400 * will ever be posted for this context. This is only 401 * returned if task != NULL. 402 *\li #ISC_R_NOMEMORY insufficient resources 403 *\li #DNS_R_ALIAS 'name' is an alias for another name. 404 * 405 * Calls, and returns error codes from: 406 * 407 *\li isc_stdtime_get() 408 * 409 * Notes: 410 * 411 *\li No internal reference to "name" exists after this function 412 * returns. 413 */ 414 415void 416dns_adb_cancelfind(dns_adbfind_t *find); 417/*%< 418 * Cancels the find, and sends the event off to the caller. 419 * 420 * It is an error to call dns_adb_cancelfind() on a find where 421 * no event is wanted, or will ever be sent. 422 * 423 * Note: 424 * 425 *\li It is possible that the real completion event was posted just 426 * before the dns_adb_cancelfind() call was made. In this case, 427 * dns_adb_cancelfind() will do nothing. The event callback needs 428 * to be prepared to find this situation (i.e. result is valid but 429 * the caller expects it to be canceled). 430 * 431 * Requires: 432 * 433 *\li 'find' be a valid dns_adbfind_t pointer. 434 * 435 *\li events would have been posted to the task. This can be checked 436 * with (find->options & DNS_ADBFIND_WANTEVENT). 437 * 438 * Ensures: 439 * 440 *\li The event was posted to the task. 441 */ 442 443void 444dns_adb_destroyfind(dns_adbfind_t **find); 445/*%< 446 * Destroys the find reference. 447 * 448 * Note: 449 * 450 *\li This can only be called after the event was delivered for a 451 * find. Additionally, the event MUST have been freed via 452 * isc_event_free() BEFORE this function is called. 453 * 454 * Requires: 455 * 456 *\li 'find' != NULL and *find be valid dns_adbfind_t pointer. 457 * 458 * Ensures: 459 * 460 *\li No "address found" events will be posted to the originating task 461 * after this function returns. 462 */ 463 464void 465dns_adb_dump(dns_adb_t *adb, FILE *f); 466/*%< 467 * This function is only used for debugging. It will dump as much of the 468 * state of the running system as possible. 469 * 470 * Requires: 471 * 472 *\li adb be valid. 473 * 474 *\li f != NULL, and is a file open for writing. 475 */ 476 477void 478dns_adb_dumpfind(dns_adbfind_t *find, FILE *f); 479/*%< 480 * This function is only used for debugging. Dump the data associated 481 * with a find. 482 * 483 * Requires: 484 * 485 *\li find is valid. 486 * 487 * \li f != NULL, and is a file open for writing. 488 */ 489 490isc_result_t 491dns_adb_marklame(dns_adb_t *adb, dns_adbaddrinfo_t *addr, dns_name_t *qname, 492 dns_rdatatype_t type, isc_stdtime_t expire_time); 493/*%< 494 * Mark the given address as lame for the <qname,qtype>. expire_time should 495 * be set to the time when the entry should expire. That is, if it is to 496 * expire 10 minutes in the future, it should set it to (now + 10 * 60). 497 * 498 * Requires: 499 * 500 *\li adb be valid. 501 * 502 *\li addr be valid. 503 * 504 *\li qname be the qname used in the dns_adb_createfind() call. 505 * 506 * Returns: 507 * 508 *\li #ISC_R_SUCCESS -- all is well. 509 *\li #ISC_R_NOMEMORY -- could not mark address as lame. 510 */ 511 512/* 513 * A reasonable default for RTT adjustments 514 */ 515#define DNS_ADB_RTTADJDEFAULT 7 /*%< default scale */ 516#define DNS_ADB_RTTADJREPLACE 0 /*%< replace with our rtt */ 517#define DNS_ADB_RTTADJAGE 10 /*%< age this rtt */ 518 519void 520dns_adb_adjustsrtt(dns_adb_t *adb, dns_adbaddrinfo_t *addr, 521 unsigned int rtt, unsigned int factor); 522/*%< 523 * Mix the round trip time into the existing smoothed rtt. 524 525 * The formula used 526 * (where srtt is the existing rtt value, and rtt and factor are arguments to 527 * this function): 528 * 529 *\code 530 * new_srtt = (old_srtt / 10 * factor) + (rtt / 10 * (10 - factor)); 531 *\endcode 532 * 533 * XXXRTH Do we want to publish the formula? What if we want to change how 534 * this works later on? Recommend/require that the units are 535 * microseconds? 536 * 537 * Requires: 538 * 539 *\li adb be valid. 540 * 541 *\li addr be valid. 542 * 543 *\li 0 <= factor <= 10 544 * 545 * Note: 546 * 547 *\li The srtt in addr will be updated to reflect the new global 548 * srtt value. This may include changes made by others. 549 */ 550 551void 552dns_adb_changeflags(dns_adb_t *adb, dns_adbaddrinfo_t *addr, 553 unsigned int bits, unsigned int mask); 554/*% 555 * Change Flags. 556 * 557 * Set the flags as given by: 558 * 559 *\li newflags = (oldflags & ~mask) | (bits & mask); 560 * 561 * Requires: 562 * 563 *\li adb be valid. 564 * 565 *\li addr be valid. 566 */ 567 568isc_result_t 569dns_adb_findaddrinfo(dns_adb_t *adb, isc_sockaddr_t *sa, 570 dns_adbaddrinfo_t **addrp, isc_stdtime_t now); 571/*%< 572 * Return a dns_adbaddrinfo_t that is associated with address 'sa'. 573 * 574 * Requires: 575 * 576 *\li adb is valid. 577 * 578 *\li sa is valid. 579 * 580 *\li addrp != NULL && *addrp == NULL 581 * 582 * Returns: 583 *\li #ISC_R_SUCCESS 584 *\li #ISC_R_NOMEMORY 585 *\li #ISC_R_SHUTTINGDOWN 586 */ 587 588void 589dns_adb_freeaddrinfo(dns_adb_t *adb, dns_adbaddrinfo_t **addrp); 590/*%< 591 * Free a dns_adbaddrinfo_t allocated by dns_adb_findaddrinfo(). 592 * 593 * Requires: 594 * 595 *\li adb is valid. 596 * 597 *\li *addrp is a valid dns_adbaddrinfo_t *. 598 */ 599 600void 601dns_adb_flush(dns_adb_t *adb); 602/*%< 603 * Flushes all cached data from the adb. 604 * 605 * Requires: 606 *\li adb is valid. 607 */ 608 609void 610dns_adb_setadbsize(dns_adb_t *adb, isc_uint32_t size); 611/*%< 612 * Set a target memory size. If memory usage exceeds the target 613 * size entries will be removed before they would have expired on 614 * a random basis. 615 * 616 * If 'size' is 0 then memory usage is unlimited. 617 * 618 * Requires: 619 *\li 'adb' is valid. 620 */ 621 622void 623dns_adb_flushname(dns_adb_t *adb, dns_name_t *name); 624/*%< 625 * Flush 'name' from the adb cache. 626 * 627 * Requires: 628 *\li 'adb' is valid. 629 *\li 'name' is valid. 630 */ 631 632ISC_LANG_ENDDECLS 633 634#endif /* DNS_ADB_H */ 635