3 * - adns user-visible API (single-threaded, without any locking)
8 * Copyright (C) 1997-1999 Ian Jackson <ian@davenant.greenend.org.uk>
10 * It is part of adns, which is
11 * Copyright (C) 1997-1999 Ian Jackson <ian@davenant.greenend.org.uk>
12 * Copyright (C) 1999 Tony Finch <dot@dotat.at>
14 * This program is free software; you can redistribute it and/or modify
15 * it under the terms of the GNU General Public License as published by
16 * the Free Software Foundation; either version 2, or (at your option)
19 * This program is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
22 * GNU General Public License for more details.
25 * For the benefit of certain LGPL'd `omnibus' software which provides
26 * a uniform interface to various things including adns, I make the
27 * following additional licence. I do this because the GPL would
28 * otherwise force either the omnibus software to be GPL'd or for the
29 * adns-using part to be distributed separately.
31 * So, you may also redistribute and/or modify adns.h (but only the
32 * public header file adns.h and not any other part of adns) under the
33 * terms of the GNU Library General Public License as published by the
34 * Free Software Foundation; either version 2 of the License, or (at
35 * your option) any later version.
37 * Note that adns itself is GPL'd. Authors of adns-using applications
38 * with GPL-incompatible licences, and people who distribute adns with
39 * applications where the whole distribution is not GPL'd, are still
40 * likely to be in violation of the GPL. Anyone who wants to do this
41 * should contact Ian Jackson. Please note that to avoid encouraging
42 * people to infringe the GPL as it applies the body of adns, I think
43 * that if you take advantage of the special exception to redistribute
44 * just adns.h under the LGPL, you should retain this paragraph in its
45 * place in the appropriate copyright statements.
48 * You should have received a copy of the GNU General Public License,
49 * or the GNU Library General Public License, as appropriate, along
50 * with this program; if not, write to the Free Software Foundation,
51 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
57 #ifndef ADNS_H_INCLUDED
58 #define ADNS_H_INCLUDED
60 extern "C" { /* I really dislike this - iwj. */
65 #include <sys/socket.h>
66 #include <netinet/in.h>
67 #include <sys/types.h>
71 /* All struct in_addr anywhere in adns are in NETWORK byte order. */
73 typedef struct adns__state *adns_state;
74 typedef struct adns__query *adns_query;
77 adns_if_noenv= 0x0001, /* do not look at environment */
78 adns_if_noerrprint= 0x0002, /* never print output to stderr (_debug overrides) */
79 adns_if_noserverwarn= 0x0004, /* do not warn to stderr about duff nameservers etc */
80 adns_if_debug= 0x0008, /* enable all output to stderr plus debug msgs */
81 adns_if_noautosys= 0x0010, /* do not make syscalls at every opportunity */
82 adns_if_eintr= 0x0020, /* allow _wait and _synchronous to return EINTR */
83 adns_if_nosigpipe= 0x0040, /* applic has SIGPIPE set to SIG_IGN, do not protect */
84 adns_if_checkc_entex= 0x0100, /* do consistency checks on entry/exit to adns funcs */
85 adns_if_checkc_freq= 0x0300 /* do consistency checks very frequently (slow!) */
89 adns_qf_search= 0x00000001, /* use the searchlist */
90 adns_qf_usevc= 0x00000002, /* use a virtual circuit (TCP connection) */
91 adns_qf_owner= 0x00000004, /* fill in the owner field in the answer */
92 adns_qf_quoteok_query= 0x00000010, /* allow quote-requiring chars in query domain */
93 adns_qf_quoteok_cname= 0x00000000, /* allow ... in CNAME we go via - now default */
94 adns_qf_quoteok_anshost= 0x00000040, /* allow ... in things supposed to be hostnames */
95 adns_qf_quotefail_cname= 0x00000080, /* refuse if quote-req chars in CNAME we go via */
96 adns_qf_cname_loose= 0x00000100, /* allow refs to CNAMEs - without, get _s_cname */
97 adns_qf_cname_forbid= 0x00000200, /* don't follow CNAMEs, instead give _s_cname */
98 adns__qf_internalmask= 0x0ff00000
102 adns__rrt_typemask= 0x0ffff,
103 adns__qtf_deref= 0x10000, /* dereference domains and perhaps produce extra data */
104 adns__qtf_mail822= 0x20000, /* make mailboxes be in RFC822 rcpt field format */
111 adns_r_ns= adns_r_ns_raw|adns__qtf_deref,
116 adns_r_soa= adns_r_soa_raw|adns__qtf_mail822,
119 adns_r_ptr= adns_r_ptr_raw|adns__qtf_deref,
124 adns_r_mx= adns_r_mx_raw|adns__qtf_deref,
129 adns_r_rp= adns_r_rp_raw|adns__qtf_mail822,
131 adns_r_addr= adns_r_a|adns__qtf_deref
136 * In queries without qf_quoteok_*, all domains must have standard
137 * legal syntax, or you get adns_s_querydomainvalid (if the query
138 * domain contains bad characters) or adns_s_answerdomaininvalid (if
139 * the answer contains bad characters).
141 * In queries _with_ qf_quoteok_*, domains in the query or response
142 * may contain any characters, quoted according to RFC1035 5.1. On
143 * input to adns, the char* is a pointer to the interior of a "
144 * delimited string, except that " may appear in it, and on output,
145 * the char* is a pointer to a string which would be legal either
146 * inside or outside " delimiters, and any characters not usually
147 * legal in domain names will be quoted as \X (if the character is
148 * 33-126 except \ and ") or \DDD.
150 * If the query goes via a CNAME then the canonical name (ie, the
151 * thing that the CNAME record refers to) is usually allowed to
152 * contain any characters, which will be quoted as above. With
153 * adns_qf_quotefail_cname you get adns_s_answerdomaininvalid when
154 * this happens. (This is a change from version 0.4 and earlier, in
155 * which failing the query was the default, and you had to say
156 * adns_qf_quoteok_cname to avoid this; that flag is now deprecated.)
158 * In version 0.4 and earlier, asking for _raw records containing
159 * mailboxes without specifying _qf_quoteok_anshost was silly. This
160 * is no longer the case. In this version only parts of responses
161 * that are actually supposed to be hostnames will be refused by
162 * default if quote-requiring characters are found.
166 * If you ask for an RR which contains domains which are actually
167 * encoded mailboxes, and don't ask for the _raw version, then adns
168 * returns the mailbox formatted suitably for an RFC822 recipient
169 * header field. The particular format used is that if the mailbox
170 * requires quoting according to the rules in RFC822 then the
171 * local-part is quoted in double quotes, which end at the next
172 * unescaped double quote. (\ is the escape char, and is doubled, and
173 * is used to escape only \ and ".) Otherwise the local-part is
174 * presented as-is. In any case this is followed by an @ and the
175 * domain. The domain will not contain any characters not legal in
176 * hostnames. adns will protect the application from local parts
177 * containing control characters - these appear to be legal according
178 * to RFC822 but are clearly a bad idea.
180 * If you ask for the domain with _raw then _no_ checking is done
181 * (even on the host part, regardless of adns_qf_quoteok_anshost), and
182 * you just get the domain name in master file format.
184 * If no mailbox is supplied the returned string will be `.' in either
191 /* locally induced errors */
193 adns_s_unknownrrtype,
196 adns_s_max_localfail= 29,
198 /* remotely induced errors, detected locally */
202 adns_s_invalidresponse,
203 adns_s_unknownformat,
205 adns_s_max_remotefail= 59,
207 /* remotely induced errors, reported by remote server to us */
208 adns_s_rcodeservfail,
209 adns_s_rcodeformaterror,
210 adns_s_rcodenotimplemented,
214 adns_s_max_tempfail= 99,
216 /* remote configuration errors */
217 adns_s_inconsistent, /* PTR gives domain whose A does not exist and match */
218 adns_s_prohibitedcname, /* CNAME found where eg A expected (not if _qf_loosecname) */
219 adns_s_answerdomaininvalid,
220 adns_s_answerdomaintoolong,
223 adns_s_max_misconfig= 199,
225 /* permanent problems with the query */
226 adns_s_querydomainwrong,
227 adns_s_querydomaininvalid,
228 adns_s_querydomaintoolong,
230 adns_s_max_misquery= 299,
232 /* permanent errors */
242 struct sockaddr_in inet;
249 int naddrs; /* temp fail => -1, perm fail => 0, s_ok => >0 */
260 } adns_rr_inthostaddr;
263 /* Used both for mx_raw, in which case i is the preference and str the domain,
264 * and for txt, in which case each entry has i for the `text' length,
265 * and str for the data (which will have had an extra nul appended
266 * so that if it was plain text it is now a null-terminated string).
273 adns_rr_intstr array[2];
274 } adns_rr_intstrpair;
278 unsigned long serial, refresh, retry, expire, minimum;
283 char *cname; /* always NULL if query was for CNAME records */
284 char *owner; /* only set if requested in query flags */
285 adns_rrtype type; /* guaranteed to be same as in query */
286 time_t expires; /* expiry time, defined only if _s_ok, nxdomain or nodata. NOT TTL! */
287 int nrrs, rrsz; /* nrrs is 0 if an error occurs */
290 unsigned char *bytes;
291 char *(*str); /* ns_raw, cname, ptr, ptr_raw */
292 adns_rr_intstr *(*manyistr); /* txt (list of strings ends with i=-1, str=0) */
293 adns_rr_addr *addr; /* addr */
294 struct in_addr *inaddr; /* a */
295 adns_rr_hostaddr *hostaddr; /* ns */
296 adns_rr_intstrpair *intstrpair; /* hinfo */
297 adns_rr_strpair *strpair; /* rp, rp_raw */
298 adns_rr_inthostaddr *inthostaddr; /* mx */
299 adns_rr_intstr *intstr; /* mx_raw */
300 adns_rr_soa *soa; /* soa, soa_raw */
304 /* Memory management:
305 * adns_state and adns_query are actually pointers to malloc'd state;
306 * On submission questions are copied, including the owner domain;
307 * Answers are malloc'd as a single piece of memory; pointers in the
308 * answer struct point into further memory in the answer.
310 * Must always be non-null pointer;
311 * If *query_io is 0 to start with then any query may be returned;
312 * If *query_io is !0 adns_query then only that query may be returned.
313 * If the call is successful, *query_io, *answer_r, and *context_r
316 * Return values are 0 or an errno value.
318 * For _init, _init_strcfg, _submit and _synchronous, system errors
319 * (eg, failure to create sockets, malloc failure, etc.) return errno
322 * For _wait and _check failures are reported in the answer
323 * structure, and only 0, ESRCH or (for _check) EWOULDBLOCK is
324 * returned: if no (appropriate) requests are done adns_check returns
325 * EWOULDBLOCK; if no (appropriate) requests are outstanding both
326 * adns_query and adns_wait return ESRCH.
328 * Additionally, _wait can return EINTR if you set adns_if_eintr.
330 * All other errors (nameserver failure, timed out connections, &c)
331 * are returned in the status field of the answer. After a
332 * successful _wait or _check, if status is nonzero then nrrs will be
333 * 0, otherwise it will be >0. type will always be the type
337 int adns_init(adns_state *newstate_r, adns_initflags flags,
338 FILE *diagfile /*0=>stderr*/);
340 int adns_init_strcfg(adns_state *newstate_r, adns_initflags flags,
341 FILE *diagfile /*0=>discard*/, const char *configtext);
344 * adns_init reads /etc/resolv.conf, which is expected to be (broadly
345 * speaking) in the format expected by libresolv. adns_init_strcfg
346 * is instead passed a string which is interpreted as if it were the
347 * contents of resolv.conf. In general, configuration which is set
348 * later overrides any that is set earlier.
350 * Standard directives understood in resolv.conf:
352 * nameserver <address>
353 * Must be followed by the IP address of a nameserver. Several
354 * nameservers may be specified, and they will be tried in the order
355 * found. There is a compiled in limit, currently 5, on the number
356 * of nameservers. (libresolv supports only 3 nameservers.)
358 * search <domain> ...
359 * Specifies the search list for queries which specify
360 * adns_qf_search. This is a list of domains to append to the query
361 * domain. The query domain will be tried as-is either before all
362 * of these or after them, depending on the ndots option setting
366 * This is present only for backward compatibility with obsolete
367 * versions of libresolv. It should not be used, and is interpreted
368 * by adns as if it were `search' - note that this is subtly
369 * different to libresolv's interpretation of this directive.
371 * sortlist <addr>/<mask> ...
372 * Should be followed by a sequence of IP-address and netmask pairs,
373 * separated by spaces. They may be specified as
374 * eg. 172.30.206.0/24 or 172.30.206.0/255.255.255.0. Currently up
375 * to 15 pairs may be specified (but note that libresolv only
376 * supports up to 10).
379 * Should followed by one or more options, separated by spaces.
380 * Each option consists of an option name, followed by optionally
381 * a colon and a value. Options are listed below.
383 * Non-standard directives understood in resolv.conf:
386 * Clears the list of nameservers, so that further nameserver lines
387 * start again from the beginning.
390 * The specified file will be read.
392 * Additionally, adns will ignore lines in resolv.conf which start with a #.
394 * Standard options understood:
397 * Enables debugging output from the resolver, which will be written
401 * Affects whether queries with adns_qf_search will be tried first
402 * without adding domains from the searchlist, or whether the bare
403 * query domain will be tried last. Queries which contain at least
404 * <count> dots will be tried bare first. The default is 1.
406 * Non-standard options understood:
411 * Changes the consistency checking frequency; this overrides the
412 * setting of adns_if_check_entex, adns_if_check_freq, or neither,
413 * in the flags passed to adns_init.
415 * There are a number of environment variables which can modify the
416 * behaviour of adns. They take effect only if adns_init is used, and
417 * the caller of adns_init can disable them using adns_if_noenv. In
418 * each case there is both a FOO and an ADNS_FOO; the latter is
419 * interpreted later so that it can override the former. Unless
420 * otherwise stated, environment variables are interpreted after
421 * resolv.conf is read, in the order they are listed here.
423 * RES_CONF, ADNS_RES_CONF
424 * A filename, whose contets are in the format of resolv.conf.
426 * RES_CONF_TEXT, ADNS_RES_CONF_TEXT
427 * A string in the format of resolv.conf.
429 * RES_OPTIONS, ADNS_RES_OPTIONS
430 * These are parsed as if they appeared in the `options' line of a
431 * resolv.conf. In addition to being parsed at this point in the
432 * sequence, they are also parsed at the very beginning before
433 * resolv.conf or any other environment variables are read, so that
434 * any debug option can affect the processing of the configuration.
436 * LOCALDOMAIN, ADNS_LOCALDOMAIN
437 * These are interpreted as if their contents appeared in a `search'
438 * line in resolv.conf.
441 int adns_synchronous(adns_state ads,
444 adns_queryflags flags,
445 adns_answer **answer_r);
447 /* NB: if you set adns_if_noautosys then _submit and _check do not
448 * make any system calls; you must use some of the asynch-io event
449 * processing functions to actually get things to happen.
452 int adns_submit(adns_state ads,
455 adns_queryflags flags,
457 adns_query *query_r);
459 int adns_check(adns_state ads,
460 adns_query *query_io,
461 adns_answer **answer_r,
464 int adns_wait(adns_state ads,
465 adns_query *query_io,
466 adns_answer **answer_r,
469 /* same as adns_wait but uses poll(2) internally */
470 int adns_wait_poll(adns_state ads,
471 adns_query *query_io,
472 adns_answer **answer_r,
475 void adns_cancel(adns_query query);
477 /* The adns_query you get back from _submit is valid (ie, can be
478 * legitimately passed into adns functions) until it is returned by
479 * adns_check or adns_wait, or passed to adns_cancel. After that it
480 * must not be used. You can rely on it not being reused until the
481 * first adns_submit or _transact call using the same adns_state after
482 * it became invalid, so you may compare it for equality with other
483 * query handles until you next call _query or _transact.
485 * _submit and _synchronous return ENOSYS if they don't understand the
489 int adns_submit_reverse(adns_state ads,
490 const struct sockaddr *addr,
492 adns_queryflags flags,
494 adns_query *query_r);
495 /* type must be _r_ptr or _r_ptr_raw. _qf_search is ignored. */
497 void adns_finish(adns_state ads);
498 /* You may call this even if you have queries outstanding;
499 * they will be cancelled.
503 void adns_forallqueries_begin(adns_state ads);
504 adns_query adns_forallqueries_next(adns_state ads, void **context_r);
505 /* Iterator functions, which you can use to loop over the outstanding
506 * (submitted but not yet successfuly checked/waited) queries.
508 * You can only have one iteration going at once. You may call _begin
509 * at any time; after that, an iteration will be in progress. You may
510 * only call _next when an iteration is in progress - anything else
511 * may coredump. The iteration remains in progress until _next
512 * returns 0, indicating that all the queries have been walked over,
513 * or ANY other adns function is called with the same adns_state (or a
514 * query in the same adns_state). There is no need to explicitly
515 * finish an iteration.
517 * context_r may be 0. *context_r may not be set when _next returns 0.
520 void adns_checkconsistency(adns_state ads, adns_query qu);
521 /* Checks the consistency of adns's internal data structures.
522 * If any error is found, the program will abort().
523 * You may pass 0 for qu; if you pass non-null then additional checks
524 * are done to make sure that qu is a valid query.
528 * Example expected/legal calling sequence for submit/check/wait:
534 * adns_check 3 -> EWOULDBLOCK
542 * Entrypoints for generic asynch io:
543 * (these entrypoints are not very useful except in combination with *
544 * some of the other I/O model calls which can tell you which fds to
547 * Note that any adns call may cause adns to open and close fds, so
548 * you must call beforeselect or beforepoll again just before
549 * blocking, or you may not have an up-to-date list of it's fds.
552 int adns_processany(adns_state ads);
553 /* Gives adns flow-of-control for a bit. This will never block, and
554 * can be used with any threading/asynch-io model. If some error
555 * occurred which might cause an event loop to spin then the errno
559 int adns_processreadable(adns_state ads, int fd, const struct timeval *now);
560 int adns_processwriteable(adns_state ads, int fd, const struct timeval *now);
561 int adns_processexceptional(adns_state ads, int fd, const struct timeval *now);
562 /* Gives adns flow-of-control so that it can process incoming data
563 * from, or send outgoing data via, fd. Very like _processany. If it
564 * returns zero then fd will no longer be readable or writeable
565 * (unless of course more data has arrived since). adns will _only_
566 * use that fd and only in the manner specified, regardless of whether
567 * adns_if_noautosys was specified.
569 * adns_processexceptional should be called when select(2) reports an
570 * exceptional condition, or poll(2) reports POLLPRI.
572 * It is fine to call _processreabable or _processwriteable when the
573 * fd is not ready, or with an fd that doesn't belong to adns; it will
574 * then just return 0.
576 * If some error occurred which might prevent an event loop to spin
577 * then the errno value is returned.
580 void adns_processtimeouts(adns_state ads, const struct timeval *now);
581 /* Gives adns flow-of-control so that it can process any timeouts
582 * which might have happened. Very like _processreadable/writeable.
584 * now may be 0; if it isn't, *now must be the current time, recently
585 * obtained from gettimeofday.
588 void adns_firsttimeout(adns_state ads,
589 struct timeval **tv_mod, struct timeval *tv_buf,
591 /* Asks adns when it would first like the opportunity to time
592 * something out. now must be the current time, from gettimeofday.
594 * If tv_mod points to 0 then tv_buf must be non-null, and
595 * _firsttimeout will fill in *tv_buf with the time until the first
596 * timeout, and make *tv_mod point to tv_buf. If adns doesn't have
597 * anything that might need timing out it will leave *tv_mod as 0.
599 * If *tv_mod is not 0 then tv_buf is not used. adns will update
600 * *tv_mod if it has any earlier timeout, and leave it alone if it
603 * This call will not actually do any I/O, or change the fds that adns
604 * is using. It always succeeds and never blocks.
607 void adns_globalsystemfailure(adns_state ads);
608 /* If serious problem(s) happen which globally affect your ability to
609 * interact properly with adns, or adns's ability to function
610 * properly, you or adns can call this function.
612 * All currently outstanding queries will be made to fail with
613 * adns_s_systemfail, and adns will close any stream sockets it has
616 * This is used by adns, for example, if gettimeofday() fails.
617 * Without this the program's event loop might start to spin !
619 * This call will never block.
623 * Entrypoints for select-loop based asynch io:
626 void adns_beforeselect(adns_state ads, int *maxfd, fd_set *readfds,
627 fd_set *writefds, fd_set *exceptfds,
628 struct timeval **tv_mod, struct timeval *tv_buf,
629 const struct timeval *now);
630 /* Find out file descriptors adns is interested in, and when it would
631 * like the opportunity to time something out. If you do not plan to
632 * block then tv_mod may be 0. Otherwise, tv_mod and tv_buf are as
633 * for adns_firsttimeout. readfds, writefds, exceptfds and maxfd_io may
636 * If *now is not 0 then this will never actually do any I/O, or
637 * change the fds that adns is using or the timeouts it wants. In any
638 * case it won't block.
641 void adns_afterselect(adns_state ads, int maxfd, const fd_set *readfds,
642 const fd_set *writefds, const fd_set *exceptfds,
643 const struct timeval *now);
644 /* Gives adns flow-of-control for a bit; intended for use after
645 * select. This is just a fancy way of calling adns_processreadable/
646 * writeable/timeouts as appropriate, as if select had returned the
647 * data being passed. Always succeeds.
651 * Example calling sequence:
653 * adns_init _noautosys
659 * adns_submit / adns_check
665 * Entrypoints for poll-loop based asynch io:
669 /* In case your system doesn't have it or you forgot to include
670 * <sys/poll.h>, to stop the following declarations from causing
671 * problems. If your system doesn't have poll then the following
672 * entrypoints will not be defined in libadns. Sorry !
675 int adns_beforepoll(adns_state ads, struct pollfd *fds, int *nfds_io, int *timeout_io,
676 const struct timeval *now);
677 /* Finds out which fd's adns is interested in, and when it would like
678 * to be able to time things out. This is in a form suitable for use
681 * On entry, usually fds should point to at least *nfds_io structs.
682 * adns will fill up to that many structs will information for poll,
683 * and record in *nfds_io how many structs it filled. If it wants to
684 * listen for more structs then *nfds_io will be set to the number
685 * required and _beforepoll will return ERANGE.
687 * You may call _beforepoll with fds==0 and *nfds_io 0, in which case
688 * adns will fill in the number of fds that it might be interested in
689 * in *nfds_io, and always return either 0 (if it is not interested in
690 * any fds) or ERANGE (if it is).
692 * NOTE that (unless now is 0) adns may acquire additional fds
693 * from one call to the next, so you must put adns_beforepoll in a
694 * loop, rather than assuming that the second call (with the buffer
695 * size requested by the first) will not return ERANGE.
697 * adns only ever sets POLLIN, POLLOUT and POLLPRI in its pollfd
698 * structs, and only ever looks at those bits. POLLPRI is required to
699 * detect TCP Urgent Data (which should not be used by a DNS server)
700 * so that adns can know that the TCP stream is now useless.
702 * In any case, *timeout_io should be a timeout value as for poll(2),
703 * which adns will modify downwards as required. If the caller does
704 * not plan to block then *timeout_io should be 0 on entry, or
705 * alternatively, timeout_io may be 0. (Alternatively, the caller may
706 * use _beforeselect with timeout_io==0 to find out about file
707 * descriptors, and use _firsttimeout is used to find out when adns
708 * might want to time something out.)
710 * adns_beforepoll will return 0 on success, and will not fail for any
711 * reason other than the fds buffer being too small (ERANGE).
713 * This call will never actually do any I/O. If you supply the
714 * current time it will not change the fds that adns is using or the
717 * In any case this call won't block.
720 #define ADNS_POLLFDS_RECOMMENDED 2
721 /* If you allocate an fds buf with at least RECOMMENDED entries then
722 * you are unlikely to need to enlarge it. You are recommended to do
723 * so if it's convenient. However, you must be prepared for adns to
724 * require more space than this.
727 void adns_afterpoll(adns_state ads, const struct pollfd *fds, int nfds,
728 const struct timeval *now);
729 /* Gives adns flow-of-control for a bit; intended for use after
730 * poll(2). fds and nfds should be the results from poll(). pollfd
731 * structs mentioning fds not belonging to adns will be ignored.
735 adns_status adns_rr_info(adns_rrtype type,
736 const char **rrtname_r, const char **fmtname_r,
738 const void *datap, char **data_r);
741 * Get information about a query type, or convert reply data to a
742 * textual form. type must be specified, and the official name of the
743 * corresponding RR type will be returned in *rrtname_r, and
744 * information about the processing style in *fmtname_r. The length
745 * of the table entry in an answer for that type will be returned in
746 * in *len_r. Any or all of rrtname_r, fmtname_r and len_r may be 0.
747 * If fmtname_r is non-null then *fmtname_r may be null on return,
748 * indicating that no special processing is involved.
750 * data_r be must be non-null iff datap is. In this case *data_r will
751 * be set to point to a string pointing to a representation of the RR
752 * data in master file format. (The owner name, timeout, class and
753 * type will not be present - only the data part of the RR.) The
754 * memory will have been obtained from malloc() and must be freed by
757 * Usually this routine will succeed. Possible errors include:
759 * adns_s_rrtypeunknown
760 * adns_s_invaliddata (*datap contained garbage)
761 * If an error occurs then no memory has been allocated,
762 * and *rrtname_r, *fmtname_r, *len_r and *data_r are undefined.
764 * There are some adns-invented data formats which are not official
765 * master file formats. These include:
767 * Mailboxes if __qtf_mail822: these are just included as-is.
769 * Addresses (adns_rr_addr): these may be of pretty much any type.
770 * The representation is in two parts: first, a word for the address
771 * family (ie, in AF_XXX, the XXX), and then one or more items for the
772 * address itself, depending on the format. For an IPv4 address the
773 * syntax is INET followed by the dotted quad (from inet_ntoa).
774 * Currently only IPv4 is supported.
776 * Text strings (as in adns_rr_txt) appear inside double quotes, and
777 * use \" and \\ to represent " and \, and \xHH to represent
778 * characters not in the range 32-126.
780 * Hostname with addresses (adns_rr_hostaddr): this consists of the
781 * hostname, as usual, followed by the adns_status value, as an
782 * abbreviation, and then a descriptive string (encoded as if it were
783 * a piece of text), for the address lookup, followed by zero or more
784 * addresses enclosed in ( and ). If the result was a permanent
785 * failure, then a single ? appears instead of the ( ). If the
786 * result was a temporary failure then an empty pair of parentheses
787 * appears (which a space in between). For example, one of the NS
788 * records for greenend.org.uk comes out like
789 * ns.chiark.greenend.org.uk ok "OK" ( INET 195.224.76.132 )
790 * an MX referring to a nonexistent host might come out like:
791 * 50 sun2.nsfnet-relay.ac.uk nxdomain "No such domain" ( )
792 * and if nameserver information is not available you might get:
793 * dns2.spong.dyn.ml.org timeout "DNS query timed out" ?
796 const char *adns_strerror(adns_status st);
797 const char *adns_errabbrev(adns_status st);
798 /* Like strerror but for adns_status values. adns_errabbrev returns
799 * the abbreviation of the error - eg, for adns_s_timeout it returns
800 * "timeout". You MUST NOT call these functions with status values
801 * not returned by the same adns library.
805 } /* end of extern "C" */