3 * - adns user-visible API (single-threaded, without any locking)
6 * This file is part of adns, which is Copyright (C) 1997-1999 Ian Jackson
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 2, or (at your option)
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.
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software Foundation,
20 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
25 #ifndef ADNS_H_INCLUDED
26 #define ADNS_H_INCLUDED
28 extern "C" { /* I really dislike this - iwj. */
33 #include <sys/socket.h>
34 #include <netinet/in.h>
35 #include <sys/types.h>
39 /* All struct in_addr anywhere in adns are in NETWORK byte order. */
41 typedef struct adns__state *adns_state;
42 typedef struct adns__query *adns_query;
45 adns_if_noenv= 0x0001, /* do not look at environment */
46 adns_if_noerrprint= 0x0002, /* never print output to stderr (_debug overrides) */
47 adns_if_noserverwarn= 0x0004, /* do not warn to stderr about duff nameservers etc */
48 adns_if_debug= 0x0008, /* enable all output to stderr plus debug msgs */
49 adns_if_noautosys= 0x0010, /* do not make syscalls at every opportunity */
50 adns_if_eintr= 0x0020, /* allow _wait and _synchronous to return EINTR */
51 adns_if_nosigpipe= 0x0040, /* applic has SIGPIPE set to SIG_IGN, do not protect */
52 adns_if_checkc_entex= 0x0100, /* do consistency checks on entry/exit to adns funcs */
53 adns_if_checkc_freq= 0x0300, /* do consistency checks very frequently (slow!) */
57 adns_qf_search= 0x00000001, /* use the searchlist */
58 adns_qf_usevc= 0x00000002, /* use a virtual circuit (TCP connection) */
59 adns_qf_owner= 0x00000004, /* fill in the owner field in the answer */
60 adns_qf_quoteok_query= 0x00000010, /* allow quote-requiring chars in query domain */
61 adns_qf_quoteok_cname= 0x00000000, /* allow ... in CNAME we go via - now default */
62 adns_qf_quoteok_anshost= 0x00000040, /* allow ... in things supposed to be hostnames */
63 adns_qf_quotefail_cname= 0x00000080, /* refuse if quote-req chars in CNAME we go via */
64 adns_qf_cname_loose= 0x00000100, /* allow refs to CNAMEs - without, get _s_cname */
65 adns_qf_cname_forbid= 0x00000200, /* don't follow CNAMEs, instead give _s_cname */
66 adns__qf_internalmask= 0x0ff00000
70 adns__rrt_typemask= 0x0ffff,
71 adns__qtf_deref= 0x10000, /* dereference domains and perhaps produce extra data */
72 adns__qtf_mail822= 0x20000, /* make mailboxes be in RFC822 rcpt field format */
79 adns_r_ns= adns_r_ns_raw|adns__qtf_deref,
84 adns_r_soa= adns_r_soa_raw|adns__qtf_mail822,
87 adns_r_ptr= adns_r_ptr_raw|adns__qtf_deref,
92 adns_r_mx= adns_r_mx_raw|adns__qtf_deref,
97 adns_r_rp= adns_r_rp_raw|adns__qtf_mail822,
99 adns_r_addr= adns_r_a|adns__qtf_deref
104 * In queries without qf_quoteok_*, all domains must have standard
105 * legal syntax, or you get adns_s_querydomainvalid (if the query
106 * domain contains bad characters) or adns_s_answerdomaininvalid (if
107 * the answer contains bad characters).
109 * In queries _with_ qf_quoteok_*, domains in the query or response
110 * may contain any characters, quoted according to RFC1035 5.1. On
111 * input to adns, the char* is a pointer to the interior of a "
112 * delimited string, except that " may appear in it, and on output,
113 * the char* is a pointer to a string which would be legal either
114 * inside or outside " delimiters, and any characters not usually
115 * legal in domain names will be quoted as \X (if the character is
116 * 33-126 except \ and ") or \DDD.
118 * If the query goes via a CNAME then the canonical name (ie, the
119 * thing that the CNAME record refers to) is usually allowed to
120 * contain any characters, which will be quoted as above. With
121 * adns_qf_quotefail_cname you get adns_s_answerdomaininvalid when
122 * this happens. (This is a change from version 0.4 and earlier, in
123 * which failing the query was the default, and you had to say
124 * adns_qf_quoteok_cname to avoid this; that flag is now deprecated.)
126 * In version 0.4 and earlier, asking for _raw records containing
127 * mailboxes without specifying _qf_quoteok_anshost was silly. This
128 * is no longer the case. In this version only parts of responses
129 * that are actually supposed to be hostnames will be refused by
130 * default if quote-requiring characters are found.
134 * If you ask for an RR which contains domains which are actually
135 * encoded mailboxes, and don't ask for the _raw version, then adns
136 * returns the mailbox formatted suitably for an RFC822 recipient
137 * header field. The particular format used is that if the mailbox
138 * requires quoting according to the rules in RFC822 then the
139 * local-part is quoted in double quotes, which end at the next
140 * unescaped double quote. (\ is the escape char, and is doubled, and
141 * is used to escape only \ and ".) Otherwise the local-part is
142 * presented as-is. In any case this is followed by an @ and the
143 * domain. The domain will not contain any characters not legal in
144 * hostnames. adns will protect the application from local parts
145 * containing control characters - these appear to be legal according
146 * to RFC822 but are clearly a bad idea.
148 * If you ask for the domain with _raw then _no_ checking is done
149 * (even on the host part, regardless of adns_qf_quoteok_anshost), and
150 * you just get the domain name in master file format.
152 * If no mailbox is supplied the returned string will be `.' in either
159 /* locally induced errors */
161 adns_s_unknownrrtype,
164 adns_s_max_localfail= 29,
166 /* remotely induced errors, detected locally */
170 adns_s_invalidresponse,
171 adns_s_unknownformat,
173 adns_s_max_remotefail= 59,
175 /* remotely induced errors, reported by remote server to us */
176 adns_s_rcodeservfail,
177 adns_s_rcodeformaterror,
178 adns_s_rcodenotimplemented,
182 adns_s_max_tempfail= 99,
184 /* remote configuration errors */
185 adns_s_inconsistent, /* PTR gives domain whose A does not exist and match */
186 adns_s_prohibitedcname, /* CNAME found where eg A expected (not if _qf_loosecname) */
187 adns_s_answerdomaininvalid,
188 adns_s_answerdomaintoolong,
191 adns_s_max_misconfig= 199,
193 /* permanent problems with the query */
194 adns_s_querydomainwrong,
195 adns_s_querydomaininvalid,
196 adns_s_querydomaintoolong,
198 adns_s_max_misquery= 299,
200 /* permanent errors */
210 struct sockaddr_in inet;
217 int naddrs; /* temp fail => -1, perm fail => 0, s_ok => >0 */
228 } adns_rr_inthostaddr;
231 /* Used both for mx_raw, in which case i is the preference and str the domain,
232 * and for txt, in which case each entry has i for the `text' length,
233 * and str for the data (which will have had an extra nul appended
234 * so that if it was plain text it is now a null-terminated string).
241 adns_rr_intstr array[2];
242 } adns_rr_intstrpair;
246 unsigned long serial, refresh, retry, expire, minimum;
251 char *cname; /* always NULL if query was for CNAME records */
252 char *owner; /* only set if requested in query flags */
253 adns_rrtype type; /* guaranteed to be same as in query */
254 time_t expires; /* expiry time, defined only if _s_ok, nxdomain or nodata. NOT TTL! */
255 int nrrs, rrsz; /* nrrs is 0 if an error occurs */
258 unsigned char *bytes;
259 char *(*str); /* ns_raw, cname, ptr, ptr_raw */
260 adns_rr_intstr *(*manyistr); /* txt (list of strings ends with i=-1, str=0) */
261 adns_rr_addr *addr; /* addr */
262 struct in_addr *inaddr; /* a */
263 adns_rr_hostaddr *hostaddr; /* ns */
264 adns_rr_intstrpair *intstrpair; /* hinfo */
265 adns_rr_strpair *strpair; /* rp, rp_raw */
266 adns_rr_inthostaddr *inthostaddr; /* mx */
267 adns_rr_intstr *intstr; /* mx_raw */
268 adns_rr_soa *soa; /* soa, soa_raw */
272 /* Memory management:
273 * adns_state and adns_query are actually pointers to malloc'd state;
274 * On submission questions are copied, including the owner domain;
275 * Answers are malloc'd as a single piece of memory; pointers in the
276 * answer struct point into further memory in the answer.
278 * Must always be non-null pointer;
279 * If *query_io is 0 to start with then any query may be returned;
280 * If *query_io is !0 adns_query then only that query may be returned.
281 * If the call is successful, *query_io, *answer_r, and *context_r
284 * Return values are 0 or an errno value.
286 * For _init, _init_strcfg, _submit and _synchronous, system errors
287 * (eg, failure to create sockets, malloc failure, etc.) return errno
290 * For _wait and _check failures are reported in the answer
291 * structure, and only 0, ESRCH or (for _check) EWOULDBLOCK is
292 * returned: if no (appropriate) requests are done adns_check returns
293 * EWOULDBLOCK; if no (appropriate) requests are outstanding both
294 * adns_query and adns_wait return ESRCH.
296 * Additionally, _wait can return EINTR if you set adns_if_eintr.
298 * All other errors (nameserver failure, timed out connections, &c)
299 * are returned in the status field of the answer. After a
300 * successful _wait or _check, if status is nonzero then nrrs will be
301 * 0, otherwise it will be >0. type will always be the type
305 int adns_init(adns_state *newstate_r, adns_initflags flags,
306 FILE *diagfile /*0=>stderr*/);
308 int adns_init_strcfg(adns_state *newstate_r, adns_initflags flags,
309 FILE *diagfile /*0=>discard*/, const char *configtext);
311 int adns_synchronous(adns_state ads,
314 adns_queryflags flags,
315 adns_answer **answer_r);
317 /* NB: if you set adns_if_noautosys then _submit and _check do not
318 * make any system calls; you must use some of the asynch-io event
319 * processing functions to actually get things to happen.
322 int adns_submit(adns_state ads,
325 adns_queryflags flags,
327 adns_query *query_r);
329 int adns_check(adns_state ads,
330 adns_query *query_io,
331 adns_answer **answer_r,
334 int adns_wait(adns_state ads,
335 adns_query *query_io,
336 adns_answer **answer_r,
339 /* same as adns_wait but uses poll(2) internally */
340 int adns_wait_poll(adns_state ads,
341 adns_query *query_io,
342 adns_answer **answer_r,
345 void adns_cancel(adns_query query);
347 /* The adns_query you get back from _submit is valid (ie, can be
348 * legitimately passed into adns functions) until it is returned by
349 * adns_check or adns_wait, or passed to adns_cancel. After that it
350 * must not be used. You can rely on it not being reused until the
351 * first adns_submit or _transact call using the same adns_state after
352 * it became invalid, so you may compare it for equality with other
353 * query handles until you next call _query or _transact.
355 * _submit and _synchronous return ENOSYS if they don't understand the
359 int adns_submit_reverse(adns_state ads,
360 const struct sockaddr *addr,
362 adns_queryflags flags,
364 adns_query *query_r);
365 /* type must be _r_ptr or _r_ptr_raw. _qf_search is ignored. */
367 void adns_finish(adns_state ads);
368 /* You may call this even if you have queries outstanding;
369 * they will be cancelled.
373 void adns_forallqueries_begin(adns_state ads);
374 adns_query adns_forallqueries_next(adns_state ads, void **context_r);
375 /* Iterator functions, which you can use to loop over the outstanding
376 * (submitted but not yet successfuly checked/waited) queries.
378 * You can only have one iteration going at once. You may call _begin
379 * at any time; after that, an iteration will be in progress. You may
380 * only call _next when an iteration is in progress - anything else
381 * may coredump. The iteration remains in progress until _next
382 * returns 0, indicating that all the queries have been walked over,
383 * or ANY other adns function is called with the same adns_state (or a
384 * query in the same adns_state). There is no need to explicitly
385 * finish an iteration.
387 * context_r may be 0. *context_r may not be set when _next returns 0.
390 void adns_checkconsistency(adns_state ads, adns_query qu);
391 /* Checks the consistency of adns's internal data structures.
392 * If any error is found, the program will abort().
393 * You may pass 0 for qu; if you pass non-null then additional checks
394 * are done to make sure that qu is a valid query.
398 * Example expected/legal calling sequence for submit/check/wait:
404 * adns_check 3 -> EWOULDBLOCK
412 * Entrypoints for generic asynch io:
413 * (these entrypoints are not very useful except in combination with *
414 * some of the other I/O model calls which can tell you which fds to
417 * Note that any adns call may cause adns to open and close fds, so
418 * you must call beforeselect or beforepoll again just before
419 * blocking, or you may not have an up-to-date list of it's fds.
422 int adns_processany(adns_state ads);
423 /* Gives adns flow-of-control for a bit. This will never block, and
424 * can be used with any threading/asynch-io model. If some error
425 * occurred which might cause an event loop to spin then the errno
429 int adns_processreadable(adns_state ads, int fd, const struct timeval *now);
430 int adns_processwriteable(adns_state ads, int fd, const struct timeval *now);
431 int adns_processexceptional(adns_state ads, int fd, const struct timeval *now);
432 /* Gives adns flow-of-control so that it can process incoming data
433 * from, or send outgoing data via, fd. Very like _processany. If it
434 * returns zero then fd will no longer be readable or writeable
435 * (unless of course more data has arrived since). adns will _only_
436 * that fd and only in the manner specified, regardless of whether
437 * adns_if_noautosys was specified.
439 * adns_processexceptional should be called when select(2) reports an
440 * exceptional condition, or poll(2) reports POLLPRI.
442 * It is fine to call _processreabable or _processwriteable when the
443 * fd is not ready, or with an fd that doesn't belong to adns; it will
444 * then just return 0.
446 * If some error occurred which might prevent an event loop to spin
447 * then the errno value is returned.
450 void adns_processtimeouts(adns_state ads, const struct timeval *now);
451 /* Gives adns flow-of-control so that it can process any timeouts
452 * which might have happened. Very like _processreadable/writeable.
454 * now may be 0; if it isn't, *now must be the current time, recently
455 * obtained from gettimeofday.
458 void adns_firsttimeout(adns_state ads,
459 struct timeval **tv_mod, struct timeval *tv_buf,
461 /* Asks adns when it would first like the opportunity to time
462 * something out. now must be the current time, from gettimeofday.
464 * If tv_mod points to 0 then tv_buf must be non-null, and
465 * _firsttimeout will fill in *tv_buf with the time until the first
466 * timeout, and make *tv_mod point to tv_buf. If adns doesn't have
467 * anything that might need timing out it will leave *tv_mod as 0.
469 * If *tv_mod is not 0 then tv_buf is not used. adns will update
470 * *tv_mod if it has any earlier timeout, and leave it alone if it
473 * This call will not actually do any I/O, or change the fds that adns
474 * is using. It always succeeds and never blocks.
477 void adns_globalsystemfailure(adns_state ads);
478 /* If serious problem(s) happen which globally affect your ability to
479 * interact properly with adns, or adns's ability to function
480 * properly, you or adns can call this function.
482 * All currently outstanding queries will be made to fail with
483 * adns_s_systemfail, and adns will close any stream sockets it has
486 * This is used by adns, for example, if gettimeofday() fails.
487 * Without this the program's event loop might start to spin !
489 * This call will never block.
493 * Entrypoints for select-loop based asynch io:
496 void adns_beforeselect(adns_state ads, int *maxfd, fd_set *readfds,
497 fd_set *writefds, fd_set *exceptfds,
498 struct timeval **tv_mod, struct timeval *tv_buf,
499 const struct timeval *now);
500 /* Find out file descriptors adns is interested in, and when it would
501 * like the opportunity to time something out. If you do not plan to
502 * block then tv_mod may be 0. Otherwise, tv_mod and tv_buf are as
503 * for adns_firsttimeout. readfds, writefds, exceptfds and maxfd_io may
506 * If *now is not 0 then this will never actually do any I/O, or
507 * change the fds that adns is using or the timeouts it wants. In any
508 * case it won't block.
511 void adns_afterselect(adns_state ads, int maxfd, const fd_set *readfds,
512 const fd_set *writefds, const fd_set *exceptfds,
513 const struct timeval *now);
514 /* Gives adns flow-of-control for a bit; intended for use after
515 * select. This is just a fancy way of calling adns_processreadable/
516 * writeable/timeouts as appropriate, as if select had returned the
517 * data being passed. Always succeeds.
521 * Example calling sequence:
523 * adns_init _noautosys
529 * adns_submit / adns_check
535 * Entrypoints for poll-loop based asynch io:
539 /* In case your system doesn't have it or you forgot to include
540 * <sys/poll.h>, to stop the following declarations from causing
541 * problems. If your system doesn't have poll then the following
542 * entrypoints will not be defined in libadns. Sorry !
545 int adns_beforepoll(adns_state ads, struct pollfd *fds, int *nfds_io, int *timeout_io,
546 const struct timeval *now);
547 /* Finds out which fd's adns is interested in, and when it would like
548 * to be able to time things out. This is in a form suitable for use
551 * On entry, usually fds should point to at least *nfds_io structs.
552 * adns will fill up to that many structs will information for poll,
553 * and record in *nfds_io how many structs it filled. If it wants to
554 * listen for more structs then *nfds_io will be set to the number
555 * required and _beforepoll will return ERANGE.
557 * You may call _beforepoll with fds==0 and *nfds_io 0, in which case
558 * adns will fill in the number of fds that it might be interested in
559 * in *nfds_io, and always return either 0 (if it is not interested in
560 * any fds) or ERANGE (if it is).
562 * NOTE that (unless now is 0) adns may acquire additional fds
563 * from one call to the next, so you must put adns_beforepoll in a
564 * loop, rather than assuming that the second call (with the buffer
565 * size requested by the first) will not return ERANGE.
567 * adns only ever sets POLLIN, POLLOUT and POLLPRI in its pollfd
568 * structs, and only ever looks at those bits. POLLPRI is required to
569 * detect TCP Urgent Data (which should not be used by a DNS server)
570 * so that adns can know that the TCP stream is now useless.
572 * In any case, *timeout_io should be a timeout value as for poll(2),
573 * which adns will modify downwards as required. If the caller does
574 * not plan to block then *timeout_io should be 0 on entry, or
575 * alternatively, timeout_io may be 0. (Alternatively, the caller may
576 * use _beforeselect with timeout_io==0 to find out about file
577 * descriptors, and use _firsttimeout is used to find out when adns
578 * might want to time something out.)
580 * adns_beforepoll will return 0 on success, and will not fail for any
581 * reason other than the fds buffer being too small (ERANGE).
583 * This call will never actually do any I/O. If you supply the
584 * current time it will not change the fds that adns is using or the
587 * In any case this call won't block.
590 #define ADNS_POLLFDS_RECOMMENDED 2
591 /* If you allocate an fds buf with at least RECOMMENDED entries then
592 * you are unlikely to need to enlarge it. You are recommended to do
593 * so if it's convenient. However, you must be prepared for adns to
594 * require more space than this.
597 void adns_afterpoll(adns_state ads, const struct pollfd *fds, int nfds,
598 const struct timeval *now);
599 /* Gives adns flow-of-control for a bit; intended for use after
600 * poll(2). fds and nfds should be the results from poll(). pollfd
601 * structs mentioning fds not belonging to adns will be ignored.
605 adns_status adns_rr_info(adns_rrtype type,
606 const char **rrtname_r, const char **fmtname_r,
608 const void *datap, char **data_r);
611 * Get information about a query type, or convert reply data to a
612 * textual form. type must be specified, and the official name of the
613 * corresponding RR type will be returned in *rrtname_r, and
614 * information about the processing style in *fmtname_r. The length
615 * of the table entry in an answer for that type will be returned in
616 * in *len_r. Any or all of rrtname_r, fmtname_r and len_r may be 0.
617 * If fmtname_r is non-null then *fmtname_r may be null on return,
618 * indicating that no special processing is involved.
620 * data_r be must be non-null iff datap is. In this case *data_r will
621 * be set to point to a string pointing to a representation of the RR
622 * data in master file format. (The owner name, timeout, class and
623 * type will not be present - only the data part of the RR.) The
624 * memory will have been obtained from malloc() and must be freed by
627 * Usually this routine will succeed. Possible errors include:
629 * adns_s_rrtypeunknown
630 * adns_s_invaliddata (*datap contained garbage)
631 * If an error occurs then no memory has been allocated,
632 * and *rrtname_r, *fmtname_r, *len_r and *data_r are undefined.
634 * There are some adns-invented data formats which are not official
635 * master file formats. These include:
637 * Mailboxes if __qtf_mail822: these are just included as-is.
639 * Addresses (adns_rr_addr): these may be of pretty much any type.
640 * The representation is in two parts: first, a word for the address
641 * family (ie, in AF_XXX, the XXX), and then one or more items for the
642 * address itself, depending on the format. For an IPv4 address the
643 * syntax is INET followed by the dotted quad (from inet_ntoa).
644 * Currently only IPv4 is supported.
646 * Text strings (as in adns_rr_txt) appear inside double quotes, and
647 * use \" and \\ to represent " and \, and \xHH to represent
648 * characters not in the range 32-126.
650 * Hostname with addresses (adns_rr_hostaddr): this consists of the
651 * hostname, as usual, followed by the adns_status value, as an
652 * abbreviation, and then a descriptive string (encoded as if it were
653 * a piece of text), for the address lookup, followed by zero or more
654 * addresses enclosed in ( and ). If the result was a permanent
655 * failure, then a single ? appears instead of the ( ). If the
656 * result was a temporary failure then an empty pair of parentheses
657 * appears (which a space in between). For example, one of the NS
658 * records for greenend.org.uk comes out like
659 * ns.chiark.greenend.org.uk ok "OK" ( INET 195.224.76.132 )
660 * an MX referring to a nonexistent host might come out like:
661 * 50 sun2.nsfnet-relay.ac.uk nxdomain "No such domain" ( )
662 * and if nameserver information is not available you might get:
663 * dns2.spong.dyn.ml.org timeout "DNS query timed out" ?
666 const char *adns_strerror(adns_status st);
667 const char *adns_errabbrev(adns_status st);
668 /* Like strerror but for adns_status values. adns_errabbrev returns
669 * the abbreviation of the error - eg, for adns_s_timeout it returns
670 * "timeout". You MUST NOT call these functions with status values
671 * not returned by the same adns library.
675 } /* end of extern "C" */