adb.h revision 275672
1/* 2 * Copyright (C) 2004-2008, 2011, 2013 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: adb.h,v 1.88 2011/12/05 17:10:51 each Exp $ */ 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 isc_uint32_t qtotal; 122 123 /* Private */ 124 isc_mutex_t lock; /* locks all below */ 125 in_port_t port; 126 int name_bucket; 127 unsigned int flags; 128 dns_adbname_t *adbname; 129 dns_adb_t *adb; 130 isc_event_t event; 131 ISC_LINK(dns_adbfind_t) plink; 132}; 133 134/* 135 * _INET: 136 * _INET6: 137 * return addresses of that type. 138 * 139 * _EMPTYEVENT: 140 * Only schedule an event if no addresses are known. 141 * Must set _WANTEVENT for this to be meaningful. 142 * 143 * _WANTEVENT: 144 * An event is desired. Check this bit in the returned find to see 145 * if one will actually be generated. 146 * 147 * _AVOIDFETCHES: 148 * If set, fetches will not be generated unless no addresses are 149 * available in any of the address families requested. 150 * 151 * _STARTATZONE: 152 * Fetches will start using the closest zone data or use the root servers. 153 * This is useful for reestablishing glue that has expired. 154 * 155 * _GLUEOK: 156 * _HINTOK: 157 * Glue or hints are ok. These are used when matching names already 158 * in the adb, and when dns databases are searched. 159 * 160 * _RETURNLAME: 161 * Return lame servers in a find, so that all addresses are returned. 162 * 163 * _LAMEPRUNED: 164 * At least one address was omitted from the list because it was lame. 165 * This bit will NEVER be set if _RETURNLAME is set in the createfind(). 166 */ 167/*% Return addresses of type INET. */ 168#define DNS_ADBFIND_INET 0x00000001 169/*% Return addresses of type INET6. */ 170#define DNS_ADBFIND_INET6 0x00000002 171#define DNS_ADBFIND_ADDRESSMASK 0x00000003 172/*% 173 * Only schedule an event if no addresses are known. 174 * Must set _WANTEVENT for this to be meaningful. 175 */ 176#define DNS_ADBFIND_EMPTYEVENT 0x00000004 177/*% 178 * An event is desired. Check this bit in the returned find to see 179 * if one will actually be generated. 180 */ 181#define DNS_ADBFIND_WANTEVENT 0x00000008 182/*% 183 * If set, fetches will not be generated unless no addresses are 184 * available in any of the address families requested. 185 */ 186#define DNS_ADBFIND_AVOIDFETCHES 0x00000010 187/*% 188 * Fetches will start using the closest zone data or use the root servers. 189 * This is useful for reestablishing glue that has expired. 190 */ 191#define DNS_ADBFIND_STARTATZONE 0x00000020 192/*% 193 * Glue or hints are ok. These are used when matching names already 194 * in the adb, and when dns databases are searched. 195 */ 196#define DNS_ADBFIND_GLUEOK 0x00000040 197/*% 198 * Glue or hints are ok. These are used when matching names already 199 * in the adb, and when dns databases are searched. 200 */ 201#define DNS_ADBFIND_HINTOK 0x00000080 202/*% 203 * Return lame servers in a find, so that all addresses are returned. 204 */ 205#define DNS_ADBFIND_RETURNLAME 0x00000100 206/*% 207 * Only schedule an event if no addresses are known. 208 * Must set _WANTEVENT for this to be meaningful. 209 */ 210#define DNS_ADBFIND_LAMEPRUNED 0x00000200 211 212/*% 213 * The answers to queries come back as a list of these. 214 */ 215struct dns_adbaddrinfo { 216 unsigned int magic; /*%< private */ 217 218 isc_sockaddr_t sockaddr; /*%< [rw] */ 219 unsigned int srtt; /*%< [rw] microseconds */ 220 unsigned int flags; /*%< [rw] */ 221 dns_adbentry_t *entry; /*%< private */ 222 ISC_LINK(dns_adbaddrinfo_t) publink; 223}; 224 225/*!< 226 * The event sent to the caller task is just a plain old isc_event_t. It 227 * contains no data other than a simple status, passed in the "type" field 228 * to indicate that another address resolved, or all partially resolved 229 * addresses have failed to resolve. 230 * 231 * "sender" is the dns_adbfind_t used to issue this query. 232 * 233 * This is simply a standard event, with the "type" set to: 234 * 235 *\li #DNS_EVENT_ADBMOREADDRESSES -- another address resolved. 236 *\li #DNS_EVENT_ADBNOMOREADDRESSES -- all pending addresses failed, 237 * were canceled, or otherwise will 238 * not be usable. 239 *\li #DNS_EVENT_ADBCANCELED -- The request was canceled by a 240 * 3rd party. 241 *\li #DNS_EVENT_ADBNAMEDELETED -- The name was deleted, so this request 242 * was canceled. 243 * 244 * In each of these cases, the addresses returned by the initial call 245 * to dns_adb_createfind() can still be used until they are no longer needed. 246 */ 247 248/**** 249 **** FUNCTIONS 250 ****/ 251 252 253isc_result_t 254dns_adb_create(isc_mem_t *mem, dns_view_t *view, isc_timermgr_t *tmgr, 255 isc_taskmgr_t *taskmgr, dns_adb_t **newadb); 256/*%< 257 * Create a new ADB. 258 * 259 * Notes: 260 * 261 *\li Generally, applications should not create an ADB directly, but 262 * should instead call dns_view_createresolver(). 263 * 264 * Requires: 265 * 266 *\li 'mem' must be a valid memory context. 267 * 268 *\li 'view' be a pointer to a valid view. 269 * 270 *\li 'tmgr' be a pointer to a valid timer manager. 271 * 272 *\li 'taskmgr' be a pointer to a valid task manager. 273 * 274 *\li 'newadb' != NULL && '*newadb' == NULL. 275 * 276 * Returns: 277 * 278 *\li #ISC_R_SUCCESS after happiness. 279 *\li #ISC_R_NOMEMORY after resource allocation failure. 280 */ 281 282void 283dns_adb_attach(dns_adb_t *adb, dns_adb_t **adbp); 284/*% 285 * Attach to an 'adb' to 'adbp'. 286 * 287 * Requires: 288 *\li 'adb' to be a valid dns_adb_t, created via dns_adb_create(). 289 *\li 'adbp' to be a valid pointer to a *dns_adb_t which is initialized 290 * to NULL. 291 */ 292 293void 294dns_adb_detach(dns_adb_t **adb); 295/*% 296 * Delete the ADB. Sets *ADB to NULL. Cancels any outstanding requests. 297 * 298 * Requires: 299 * 300 *\li 'adb' be non-NULL and '*adb' be a valid dns_adb_t, created via 301 * dns_adb_create(). 302 */ 303 304void 305dns_adb_whenshutdown(dns_adb_t *adb, isc_task_t *task, isc_event_t **eventp); 306/*% 307 * Send '*eventp' to 'task' when 'adb' has shutdown. 308 * 309 * Requires: 310 * 311 *\li '*adb' is a valid dns_adb_t. 312 * 313 *\li eventp != NULL && *eventp is a valid event. 314 * 315 * Ensures: 316 * 317 *\li *eventp == NULL 318 * 319 *\li The event's sender field is set to the value of adb when the event 320 * is sent. 321 */ 322 323void 324dns_adb_shutdown(dns_adb_t *adb); 325/*%< 326 * Shutdown 'adb'. 327 * 328 * Requires: 329 * 330 * \li '*adb' is a valid dns_adb_t. 331 */ 332 333isc_result_t 334dns_adb_createfind(dns_adb_t *adb, isc_task_t *task, isc_taskaction_t action, 335 void *arg, dns_name_t *name, dns_name_t *qname, 336 dns_rdatatype_t qtype, unsigned int options, 337 isc_stdtime_t now, dns_name_t *target, 338 in_port_t port, dns_adbfind_t **find); 339isc_result_t 340dns_adb_createfind2(dns_adb_t *adb, isc_task_t *task, isc_taskaction_t action, 341 void *arg, dns_name_t *name, dns_name_t *qname, 342 dns_rdatatype_t qtype, unsigned int options, 343 isc_stdtime_t now, dns_name_t *target, in_port_t port, 344 unsigned int depth, dns_adbfind_t **find); 345/*%< 346 * Main interface for clients. The adb will look up the name given in 347 * "name" and will build up a list of found addresses, and perhaps start 348 * internal fetches to resolve names that are unknown currently. 349 * 350 * If other addresses resolve after this call completes, an event will 351 * be sent to the <task, taskaction, arg> with the sender of that event 352 * set to a pointer to the dns_adbfind_t returned by this function. 353 * 354 * If no events will be generated, the *find->result_v4 and/or result_v6 355 * members may be examined for address lookup status. The usual #ISC_R_SUCCESS, 356 * #ISC_R_FAILURE, #DNS_R_NXDOMAIN, and #DNS_R_NXRRSET are returned, along with 357 * #ISC_R_NOTFOUND meaning the ADB has not _yet_ found the values. In this 358 * latter case, retrying may produce more addresses. 359 * 360 * If events will be returned, the result_v[46] members are only valid 361 * when that event is actually returned. 362 * 363 * The list of addresses returned is unordered. The caller must impose 364 * any ordering required. The list will not contain "known bad" addresses, 365 * however. For instance, it will not return hosts that are known to be 366 * lame for the zone in question. 367 * 368 * The caller cannot (directly) modify the contents of the address list's 369 * fields other than the "link" field. All values can be read at any 370 * time, however. 371 * 372 * The "now" parameter is used only for determining which entries that 373 * have a specific time to live or expire time should be removed from 374 * the running database. If specified as zero, the current time will 375 * be retrieved and used. 376 * 377 * If 'target' is not NULL and 'name' is an alias (i.e. the name is 378 * CNAME'd or DNAME'd to another name), then 'target' will be updated with 379 * the domain name that 'name' is aliased to. 380 * 381 * All addresses returned will have the sockaddr's port set to 'port.' 382 * The caller may change them directly in the dns_adbaddrinfo_t since 383 * they are copies of the internal address only. 384 * 385 * XXXMLG Document options, especially the flags which control how 386 * events are sent. 387 * 388 * Requires: 389 * 390 *\li *adb be a valid isc_adb_t object. 391 * 392 *\li If events are to be sent, *task be a valid task, 393 * and isc_taskaction_t != NULL. 394 * 395 *\li *name is a valid dns_name_t. 396 * 397 *\li qname != NULL and *qname be a valid dns_name_t. 398 * 399 *\li target == NULL or target is a valid name with a buffer. 400 * 401 *\li find != NULL && *find == NULL. 402 * 403 * Returns: 404 * 405 *\li #ISC_R_SUCCESS Addresses might have been returned, and events will be 406 * delivered for unresolved addresses. 407 *\li #ISC_R_NOMORE Addresses might have been returned, but no events 408 * will ever be posted for this context. This is only 409 * returned if task != NULL. 410 *\li #ISC_R_NOMEMORY insufficient resources 411 *\li #DNS_R_ALIAS 'name' is an alias for another name. 412 * 413 * Calls, and returns error codes from: 414 * 415 *\li isc_stdtime_get() 416 * 417 * Notes: 418 * 419 *\li No internal reference to "name" exists after this function 420 * returns. 421 */ 422 423void 424dns_adb_cancelfind(dns_adbfind_t *find); 425/*%< 426 * Cancels the find, and sends the event off to the caller. 427 * 428 * It is an error to call dns_adb_cancelfind() on a find where 429 * no event is wanted, or will ever be sent. 430 * 431 * Note: 432 * 433 *\li It is possible that the real completion event was posted just 434 * before the dns_adb_cancelfind() call was made. In this case, 435 * dns_adb_cancelfind() will do nothing. The event callback needs 436 * to be prepared to find this situation (i.e. result is valid but 437 * the caller expects it to be canceled). 438 * 439 * Requires: 440 * 441 *\li 'find' be a valid dns_adbfind_t pointer. 442 * 443 *\li events would have been posted to the task. This can be checked 444 * with (find->options & DNS_ADBFIND_WANTEVENT). 445 * 446 * Ensures: 447 * 448 *\li The event was posted to the task. 449 */ 450 451void 452dns_adb_destroyfind(dns_adbfind_t **find); 453/*%< 454 * Destroys the find reference. 455 * 456 * Note: 457 * 458 *\li This can only be called after the event was delivered for a 459 * find. Additionally, the event MUST have been freed via 460 * isc_event_free() BEFORE this function is called. 461 * 462 * Requires: 463 * 464 *\li 'find' != NULL and *find be valid dns_adbfind_t pointer. 465 * 466 * Ensures: 467 * 468 *\li No "address found" events will be posted to the originating task 469 * after this function returns. 470 */ 471 472void 473dns_adb_dump(dns_adb_t *adb, FILE *f); 474/*%< 475 * This function is only used for debugging. It will dump as much of the 476 * state of the running system as possible. 477 * 478 * Requires: 479 * 480 *\li adb be valid. 481 * 482 *\li f != NULL, and is a file open for writing. 483 */ 484 485void 486dns_adb_dumpfind(dns_adbfind_t *find, FILE *f); 487/*%< 488 * This function is only used for debugging. Dump the data associated 489 * with a find. 490 * 491 * Requires: 492 * 493 *\li find is valid. 494 * 495 * \li f != NULL, and is a file open for writing. 496 */ 497 498isc_result_t 499dns_adb_marklame(dns_adb_t *adb, dns_adbaddrinfo_t *addr, dns_name_t *qname, 500 dns_rdatatype_t type, isc_stdtime_t expire_time); 501/*%< 502 * Mark the given address as lame for the <qname,qtype>. expire_time should 503 * be set to the time when the entry should expire. That is, if it is to 504 * expire 10 minutes in the future, it should set it to (now + 10 * 60). 505 * 506 * Requires: 507 * 508 *\li adb be valid. 509 * 510 *\li addr be valid. 511 * 512 *\li qname be the qname used in the dns_adb_createfind() call. 513 * 514 * Returns: 515 * 516 *\li #ISC_R_SUCCESS -- all is well. 517 *\li #ISC_R_NOMEMORY -- could not mark address as lame. 518 */ 519 520/* 521 * A reasonable default for RTT adjustments 522 */ 523#define DNS_ADB_RTTADJDEFAULT 7 /*%< default scale */ 524#define DNS_ADB_RTTADJREPLACE 0 /*%< replace with our rtt */ 525#define DNS_ADB_RTTADJAGE 10 /*%< age this rtt */ 526 527void 528dns_adb_adjustsrtt(dns_adb_t *adb, dns_adbaddrinfo_t *addr, 529 unsigned int rtt, unsigned int factor); 530/*%< 531 * Mix the round trip time into the existing smoothed rtt. 532 533 * The formula used 534 * (where srtt is the existing rtt value, and rtt and factor are arguments to 535 * this function): 536 * 537 *\code 538 * new_srtt = (old_srtt / 10 * factor) + (rtt / 10 * (10 - factor)); 539 *\endcode 540 * 541 * XXXRTH Do we want to publish the formula? What if we want to change how 542 * this works later on? Recommend/require that the units are 543 * microseconds? 544 * 545 * Requires: 546 * 547 *\li adb be valid. 548 * 549 *\li addr be valid. 550 * 551 *\li 0 <= factor <= 10 552 * 553 * Note: 554 * 555 *\li The srtt in addr will be updated to reflect the new global 556 * srtt value. This may include changes made by others. 557 */ 558 559void 560dns_adb_changeflags(dns_adb_t *adb, dns_adbaddrinfo_t *addr, 561 unsigned int bits, unsigned int mask); 562/*% 563 * Change Flags. 564 * 565 * Set the flags as given by: 566 * 567 *\li newflags = (oldflags & ~mask) | (bits & mask); 568 * 569 * Requires: 570 * 571 *\li adb be valid. 572 * 573 *\li addr be valid. 574 */ 575 576isc_result_t 577dns_adb_findaddrinfo(dns_adb_t *adb, isc_sockaddr_t *sa, 578 dns_adbaddrinfo_t **addrp, isc_stdtime_t now); 579/*%< 580 * Return a dns_adbaddrinfo_t that is associated with address 'sa'. 581 * 582 * Requires: 583 * 584 *\li adb is valid. 585 * 586 *\li sa is valid. 587 * 588 *\li addrp != NULL && *addrp == NULL 589 * 590 * Returns: 591 *\li #ISC_R_SUCCESS 592 *\li #ISC_R_NOMEMORY 593 *\li #ISC_R_SHUTTINGDOWN 594 */ 595 596void 597dns_adb_freeaddrinfo(dns_adb_t *adb, dns_adbaddrinfo_t **addrp); 598/*%< 599 * Free a dns_adbaddrinfo_t allocated by dns_adb_findaddrinfo(). 600 * 601 * Requires: 602 * 603 *\li adb is valid. 604 * 605 *\li *addrp is a valid dns_adbaddrinfo_t *. 606 */ 607 608void 609dns_adb_flush(dns_adb_t *adb); 610/*%< 611 * Flushes all cached data from the adb. 612 * 613 * Requires: 614 *\li adb is valid. 615 */ 616 617void 618dns_adb_setadbsize(dns_adb_t *adb, size_t size); 619/*%< 620 * Set a target memory size. If memory usage exceeds the target 621 * size entries will be removed before they would have expired on 622 * a random basis. 623 * 624 * If 'size' is 0 then memory usage is unlimited. 625 * 626 * Requires: 627 *\li 'adb' is valid. 628 */ 629 630void 631dns_adb_flushname(dns_adb_t *adb, dns_name_t *name); 632/*%< 633 * Flush 'name' from the adb cache. 634 * 635 * Requires: 636 *\li 'adb' is valid. 637 *\li 'name' is valid. 638 */ 639 640ISC_LANG_ENDDECLS 641 642#endif /* DNS_ADB_H */ 643