3 * - adns user-visible API (single-threaded, without any locking)
8 * Copyright (C) 1997-2000 Ian Jackson <ian@davenant.greenend.org.uk>
10 * It is part of adns, which is
11 * Copyright (C) 1997-2000 Ian Jackson <ian@davenant.greenend.org.uk>
12 * Copyright (C) 1999-2000 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
26 * provides a uniform interface to various things including adns, I
27 * make the following additional licence. I do this because the GPL
28 * would otherwise force either the omnibus software to be GPL'd or
29 * the 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 to the body of adns, Ian
43 * thinks that if you take advantage of the special exception to
44 * redistribute just adns.h under the LGPL, you should retain this
45 * paragraph in its 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.
56 #ifndef ADNS_H_INCLUDED
57 #define ADNS_H_INCLUDED
59 #ifdef ADNS_JGAA_WIN32
60 # include "adns_win32.h"
63 # include <sys/socket.h>
64 # include <netinet/in.h>
65 # include <sys/types.h>
66 # include <sys/time.h>
70 # define ADNS_SOCKET int
71 # define adns_socket_close(sck) close(sck)
72 # define adns_socket_read(sck, data, len) read(sck, data, len)
73 # define adns_socket_write(sck, data, len) write(sck, data, len)
74 # define ADNS_CAPTURE_ERRNO {}
75 # define ADNS_CLEAR_ERRNO {}
79 extern "C" { /* I really dislike this - iwj. */
82 /* All struct in_addr anywhere in adns are in NETWORK byte order. */
84 typedef struct adns__state
*adns_state
;
85 typedef struct adns__query
*adns_query
;
88 adns_if_noenv
= 0x0001, /* do not look at environment */
89 adns_if_noerrprint
= 0x0002, /* never print output to stderr (_debug overrides) */
90 adns_if_noserverwarn
= 0x0004, /* do not warn to stderr about duff nameservers etc */
91 adns_if_debug
= 0x0008, /* enable all output to stderr plus debug msgs */
92 adns_if_logpid
= 0x0080, /* include pid in diagnostic output */
93 adns_if_noautosys
= 0x0010, /* do not make syscalls at every opportunity */
94 adns_if_eintr
= 0x0020, /* allow _wait and _synchronous to return EINTR */
95 adns_if_nosigpipe
= 0x0040, /* applic has SIGPIPE set to SIG_IGN, do not protect */
96 adns_if_checkc_entex
= 0x0100, /* do consistency checks on entry/exit to adns funcs */
97 adns_if_checkc_freq
= 0x0300 /* do consistency checks very frequently (slow!) */
101 adns_qf_search
= 0x00000001, /* use the searchlist */
102 adns_qf_usevc
= 0x00000002, /* use a virtual circuit (TCP connection) */
103 adns_qf_owner
= 0x00000004, /* fill in the owner field in the answer */
104 adns_qf_quoteok_query
= 0x00000010, /* allow special chars in query domain */
105 adns_qf_quoteok_cname
= 0x00000000, /* allow ... in CNAME we go via - now default */
106 adns_qf_quoteok_anshost
= 0x00000040, /* allow ... in things supposed to be hostnames */
107 adns_qf_quotefail_cname
= 0x00000080, /* refuse if quote-req chars in CNAME we go via */
108 adns_qf_cname_loose
= 0x00000100, /* allow refs to CNAMEs - without, get _s_cname */
109 adns_qf_cname_forbid
= 0x00000200, /* don't follow CNAMEs, instead give _s_cname */
110 adns__qf_internalmask
= 0x0ff00000
114 adns__rrt_typemask
= 0x0ffff,
115 adns__qtf_deref
= 0x10000, /* dereference domains and perhaps produce extra data */
116 adns__qtf_mail822
= 0x20000, /* make mailboxes be in RFC822 rcpt field format */
123 adns_r_ns
= adns_r_ns_raw
|adns__qtf_deref
,
128 adns_r_soa
= adns_r_soa_raw
|adns__qtf_mail822
,
131 adns_r_ptr
= adns_r_ptr_raw
|adns__qtf_deref
,
136 adns_r_mx
= adns_r_mx_raw
|adns__qtf_deref
,
141 adns_r_rp
= adns_r_rp_raw
|adns__qtf_mail822
,
143 adns_r_addr
= adns_r_a
|adns__qtf_deref
148 * In queries without qf_quoteok_*, all domains must have standard
149 * legal syntax, or you get adns_s_querydomainvalid (if the query
150 * domain contains bad characters) or adns_s_answerdomaininvalid (if
151 * the answer contains bad characters).
153 * In queries _with_ qf_quoteok_*, domains in the query or response
154 * may contain any characters, quoted according to RFC1035 5.1. On
155 * input to adns, the char* is a pointer to the interior of a "
156 * delimited string, except that " may appear in it unquoted. On
157 * output, the char* is a pointer to a string which would be legal
158 * either inside or outside " delimiters; any character which isn't
159 * legal in a hostname (ie alphanumeric or hyphen) or one of _ / +
160 * (the three other punctuation characters commonly abused in domain
161 * names) will be quoted, as \X if it is a printing ASCII character or
164 * If the query goes via a CNAME then the canonical name (ie, the
165 * thing that the CNAME record refers to) is usually allowed to
166 * contain any characters, which will be quoted as above. With
167 * adns_qf_quotefail_cname you get adns_s_answerdomaininvalid when
168 * this happens. (This is a change from version 0.4 and earlier, in
169 * which failing the query was the default, and you had to say
170 * adns_qf_quoteok_cname to avoid this; that flag is now deprecated.)
172 * In version 0.4 and earlier, asking for _raw records containing
173 * mailboxes without specifying _qf_quoteok_anshost was silly. This
174 * is no longer the case. In this version only parts of responses
175 * that are actually supposed to be hostnames will be refused by
176 * default if quote-requiring characters are found.
180 * If you ask for an RR which contains domains which are actually
181 * encoded mailboxes, and don't ask for the _raw version, then adns
182 * returns the mailbox formatted suitably for an RFC822 recipient
183 * header field. The particular format used is that if the mailbox
184 * requires quoting according to the rules in RFC822 then the
185 * local-part is quoted in double quotes, which end at the next
186 * unescaped double quote (\ is the escape char, and is doubled, and
187 * is used to escape only \ and "). If the local-part is legal
188 * without quoting according to RFC822, it is presented as-is. In any
189 * case the local-part is followed by an @ and the domain. The domain
190 * will not contain any characters not legal in hostnames.
192 * Unquoted local-parts may contain any printing 7-bit ASCII
193 * except the punctuation characters ( ) < > @ , ; : \ " [ ]
194 * I.e. they may contain alphanumerics, and the following
195 * punctuation characters: ! # % ^ & * - _ = + { } .
197 * adns will reject local parts containing control characters (byte
198 * values 0-31, 127-159, and 255) - these appear to be legal according
199 * to RFC822 (at least 0-127) but are clearly a bad idea. RFC1035
200 * syntax does not make any distinction between a single RFC822
201 * quoted-string containing full stops, and a series of quoted-strings
202 * separated by full stops; adns will return anything that isn't all
203 * valid atoms as a single quoted-string. RFC822 does not allow
204 * high-bit-set characters at all, but adns does allow them in
205 * local-parts, treating them as needing quoting.
207 * If you ask for the domain with _raw then _no_ checking is done
208 * (even on the host part, regardless of adns_qf_quoteok_anshost), and
209 * you just get the domain name in master file format.
211 * If no mailbox is supplied the returned string will be `.' in either
218 /* locally induced errors */
220 adns_s_unknownrrtype
,
223 adns_s_max_localfail
= 29,
225 /* remotely induced errors, detected locally */
229 adns_s_invalidresponse
,
230 adns_s_unknownformat
,
232 adns_s_max_remotefail
= 59,
234 /* remotely induced errors, reported by remote server to us */
235 adns_s_rcodeservfail
,
236 adns_s_rcodeformaterror
,
237 adns_s_rcodenotimplemented
,
241 adns_s_max_tempfail
= 99,
243 /* remote configuration errors */
244 adns_s_inconsistent
, /* PTR gives domain whose A does not exist and match */
245 adns_s_prohibitedcname
, /* CNAME found where eg A expected (not if _qf_loosecname) */
246 adns_s_answerdomaininvalid
,
247 adns_s_answerdomaintoolong
,
250 adns_s_max_misconfig
= 199,
252 /* permanent problems with the query */
253 adns_s_querydomainwrong
,
254 adns_s_querydomaininvalid
,
255 adns_s_querydomaintoolong
,
257 adns_s_max_misquery
= 299,
259 /* permanent errors */
263 adns_s_max_permfail
= 499
271 struct sockaddr_in inet
;
278 int naddrs
; /* temp fail => -1, perm fail => 0, s_ok => >0 */
289 } adns_rr_inthostaddr
;
292 /* Used both for mx_raw, in which case i is the preference and str the domain,
293 * and for txt, in which case each entry has i for the `text' length,
294 * and str for the data (which will have had an extra nul appended
295 * so that if it was plain text it is now a null-terminated string).
302 adns_rr_intstr array
[2];
303 } adns_rr_intstrpair
;
307 unsigned long serial
, refresh
, retry
, expire
, minimum
;
312 char *cname
; /* always NULL if query was for CNAME records */
313 char *owner
; /* only set if requested in query flags, and may be 0 on error anyway */
314 adns_rrtype type
; /* guaranteed to be same as in query */
315 time_t expires
; /* expiry time, defined only if _s_ok, nxdomain or nodata. NOT TTL! */
316 int nrrs
, rrsz
; /* nrrs is 0 if an error occurs */
319 unsigned char *bytes
;
320 char *(*str
); /* ns_raw, cname, ptr, ptr_raw */
321 adns_rr_intstr
*(*manyistr
); /* txt (list of strings ends with i=-1, str=0) */
322 adns_rr_addr
*addr
; /* addr */
323 struct in_addr
*inaddr
; /* a */
324 adns_rr_hostaddr
*hostaddr
; /* ns */
325 adns_rr_intstrpair
*intstrpair
; /* hinfo */
326 adns_rr_strpair
*strpair
; /* rp, rp_raw */
327 adns_rr_inthostaddr
*inthostaddr
; /* mx */
328 adns_rr_intstr
*intstr
; /* mx_raw */
329 adns_rr_soa
*soa
; /* soa, soa_raw */
333 /* Memory management:
334 * adns_state and adns_query are actually pointers to malloc'd state;
335 * On submission questions are copied, including the owner domain;
336 * Answers are malloc'd as a single piece of memory; pointers in the
337 * answer struct point into further memory in the answer.
339 * Must always be non-null pointer;
340 * If *query_io is 0 to start with then any query may be returned;
341 * If *query_io is !0 adns_query then only that query may be returned.
342 * If the call is successful, *query_io, *answer_r, and *context_r
345 * Return values are 0 or an errno value.
347 * For _init, _init_strcfg, _submit and _synchronous, system errors
348 * (eg, failure to create sockets, malloc failure, etc.) return errno
351 * For _wait and _check failures are reported in the answer
352 * structure, and only 0, ESRCH or (for _check) EAGAIN is
353 * returned: if no (appropriate) requests are done adns_check returns
354 * EAGAIN; if no (appropriate) requests are outstanding both
355 * adns_query and adns_wait return ESRCH.
357 * Additionally, _wait can return EINTR if you set adns_if_eintr.
359 * All other errors (nameserver failure, timed out connections, &c)
360 * are returned in the status field of the answer. After a
361 * successful _wait or _check, if status is nonzero then nrrs will be
362 * 0, otherwise it will be >0. type will always be the type
366 ADNS_API
int adns_init(adns_state
*newstate_r
, adns_initflags flags
,
367 FILE *diagfile
/*0=>stderr*/);
369 /* ReactOS addition */
370 ADNS_API
void adns_addserver(adns_state state
, struct in_addr server
);
371 ADNS_API
void adns_ccf_search(adns_state ads
, const char *fn
, int lno
, const char *buf
);
373 ADNS_API
int adns_init_strcfg(adns_state
*newstate_r
, adns_initflags flags
,
374 FILE *diagfile
/*0=>discard*/, const char *configtext
);
377 * adns_init reads /etc/resolv.conf, which is expected to be (broadly
378 * speaking) in the format expected by libresolv, and then
379 * /etc/resolv-adns.conf if it exists. adns_init_strcfg is instead
380 * passed a string which is interpreted as if it were the contents of
381 * resolv.conf or resolv-adns.conf. In general, configuration which
382 * is set later overrides any that is set earlier.
384 * Standard directives understood in resolv[-adns].conf:
386 * nameserver <address>
387 * Must be followed by the IP address of a nameserver. Several
388 * nameservers may be specified, and they will be tried in the order
389 * found. There is a compiled in limit, currently 5, on the number
390 * of nameservers. (libresolv supports only 3 nameservers.)
392 * search <domain> ...
393 * Specifies the search list for queries which specify
394 * adns_qf_search. This is a list of domains to append to the query
395 * domain. The query domain will be tried as-is either before all
396 * of these or after them, depending on the ndots option setting
400 * This is present only for backward compatibility with obsolete
401 * versions of libresolv. It should not be used, and is interpreted
402 * by adns as if it were `search' - note that this is subtly
403 * different to libresolv's interpretation of this directive.
405 * sortlist <addr>/<mask> ...
406 * Should be followed by a sequence of IP-address and netmask pairs,
407 * separated by spaces. They may be specified as
408 * eg. 172.30.206.0/24 or 172.30.206.0/255.255.255.0. Currently up
409 * to 15 pairs may be specified (but note that libresolv only
410 * supports up to 10).
413 * Should followed by one or more options, separated by spaces.
414 * Each option consists of an option name, followed by optionally
415 * a colon and a value. Options are listed below.
417 * Non-standard directives understood in resolv[-adns].conf:
420 * Clears the list of nameservers, so that further nameserver lines
421 * start again from the beginning.
424 * The specified file will be read.
426 * Additionally, adns will ignore lines in resolv[-adns].conf which
429 * Standard options understood:
432 * Enables debugging output from the resolver, which will be written
436 * Affects whether queries with adns_qf_search will be tried first
437 * without adding domains from the searchlist, or whether the bare
438 * query domain will be tried last. Queries which contain at least
439 * <count> dots will be tried bare first. The default is 1.
441 * Non-standard options understood:
446 * Changes the consistency checking frequency; this overrides the
447 * setting of adns_if_check_entex, adns_if_check_freq, or neither,
448 * in the flags passed to adns_init.
450 * There are a number of environment variables which can modify the
451 * behaviour of adns. They take effect only if adns_init is used, and
452 * the caller of adns_init can disable them using adns_if_noenv. In
453 * each case there is both a FOO and an ADNS_FOO; the latter is
454 * interpreted later so that it can override the former. Unless
455 * otherwise stated, environment variables are interpreted after
456 * resolv[-adns].conf are read, in the order they are listed here.
458 * RES_CONF, ADNS_RES_CONF
459 * A filename, whose contets are in the format of resolv.conf.
461 * RES_CONF_TEXT, ADNS_RES_CONF_TEXT
462 * A string in the format of resolv.conf.
464 * RES_OPTIONS, ADNS_RES_OPTIONS
465 * These are parsed as if they appeared in the `options' line of a
466 * resolv.conf. In addition to being parsed at this point in the
467 * sequence, they are also parsed at the very beginning before
468 * resolv.conf or any other environment variables are read, so that
469 * any debug option can affect the processing of the configuration.
471 * LOCALDOMAIN, ADNS_LOCALDOMAIN
472 * These are interpreted as if their contents appeared in a `search'
473 * line in resolv.conf.
476 ADNS_API
int adns_synchronous(adns_state ads
,
479 adns_queryflags flags
,
480 adns_answer
**answer_r
);
482 /* NB: if you set adns_if_noautosys then _submit and _check do not
483 * make any system calls; you must use some of the asynch-io event
484 * processing functions to actually get things to happen.
487 ADNS_API
int adns_submit(adns_state ads
,
490 adns_queryflags flags
,
492 adns_query
*query_r
);
494 /* The owner should be quoted in master file format. */
496 ADNS_API
int adns_check(adns_state ads
,
497 adns_query
*query_io
,
498 adns_answer
**answer_r
,
501 ADNS_API
int adns_wait(adns_state ads
,
502 adns_query
*query_io
,
503 adns_answer
**answer_r
,
506 /* same as adns_wait but uses poll(2) internally */
507 ADNS_API
int adns_wait_poll(adns_state ads
,
508 adns_query
*query_io
,
509 adns_answer
**answer_r
,
512 ADNS_API
void adns_cancel(adns_query query
);
514 /* The adns_query you get back from _submit is valid (ie, can be
515 * legitimately passed into adns functions) until it is returned by
516 * adns_check or adns_wait, or passed to adns_cancel. After that it
517 * must not be used. You can rely on it not being reused until the
518 * first adns_submit or _transact call using the same adns_state after
519 * it became invalid, so you may compare it for equality with other
520 * query handles until you next call _query or _transact.
522 * _submit and _synchronous return ENOSYS if they don't understand the
526 ADNS_API
int adns_submit_reverse(adns_state ads
,
527 const struct sockaddr
*addr
,
529 adns_queryflags flags
,
531 adns_query
*query_r
);
532 /* type must be _r_ptr or _r_ptr_raw. _qf_search is ignored.
533 * addr->sa_family must be AF_INET or you get ENOSYS.
536 ADNS_API
int adns_submit_reverse_any(adns_state ads
,
537 const struct sockaddr
*addr
,
540 adns_queryflags flags
,
542 adns_query
*query_r
);
543 /* For RBL-style reverse `zone's; look up
544 * <reversed-address>.<zone>
545 * Any type is allowed. _qf_search is ignored.
546 * addr->sa_family must be AF_INET or you get ENOSYS.
549 ADNS_API
void adns_finish(adns_state ads
);
550 /* You may call this even if you have queries outstanding;
551 * they will be cancelled.
555 ADNS_API
void adns_forallqueries_begin(adns_state ads
);
556 ADNS_API adns_query
adns_forallqueries_next(adns_state ads
, void **context_r
);
557 /* Iterator functions, which you can use to loop over the outstanding
558 * (submitted but not yet successfuly checked/waited) queries.
560 * You can only have one iteration going at once. You may call _begin
561 * at any time; after that, an iteration will be in progress. You may
562 * only call _next when an iteration is in progress - anything else
563 * may coredump. The iteration remains in progress until _next
564 * returns 0, indicating that all the queries have been walked over,
565 * or ANY other adns function is called with the same adns_state (or a
566 * query in the same adns_state). There is no need to explicitly
567 * finish an iteration.
569 * context_r may be 0. *context_r may not be set when _next returns 0.
572 ADNS_API
void adns_checkconsistency(adns_state ads
, adns_query qu
);
573 /* Checks the consistency of adns's internal data structures.
574 * If any error is found, the program will abort().
575 * You may pass 0 for qu; if you pass non-null then additional checks
576 * are done to make sure that qu is a valid query.
580 * Example expected/legal calling sequence for submit/check/wait:
586 * adns_check 3 -> EAGAIN
594 * Entrypoints for generic asynch io:
595 * (these entrypoints are not very useful except in combination with *
596 * some of the other I/O model calls which can tell you which fds to
599 * Note that any adns call may cause adns to open and close fds, so
600 * you must call beforeselect or beforepoll again just before
601 * blocking, or you may not have an up-to-date list of it's fds.
604 ADNS_API
int adns_processany(adns_state ads
);
605 /* Gives adns flow-of-control for a bit. This will never block, and
606 * can be used with any threading/asynch-io model. If some error
607 * occurred which might cause an event loop to spin then the errno
611 ADNS_API
int adns_processreadable(adns_state ads
, ADNS_SOCKET fd
, const struct timeval
*now
);
612 ADNS_API
int adns_processwriteable(adns_state ads
, ADNS_SOCKET fd
, const struct timeval
*now
);
613 ADNS_API
int adns_processexceptional(adns_state ads
, ADNS_SOCKET fd
, const struct timeval
*now
);
614 /* Gives adns flow-of-control so that it can process incoming data
615 * from, or send outgoing data via, fd. Very like _processany. If it
616 * returns zero then fd will no longer be readable or writeable
617 * (unless of course more data has arrived since). adns will _only_
618 * use that fd and only in the manner specified, regardless of whether
619 * adns_if_noautosys was specified.
621 * adns_processexceptional should be called when select(2) reports an
622 * exceptional condition, or poll(2) reports POLLPRI.
624 * It is fine to call _processreabable or _processwriteable when the
625 * fd is not ready, or with an fd that doesn't belong to adns; it will
626 * then just return 0.
628 * If some error occurred which might prevent an event loop to spin
629 * then the errno value is returned.
632 ADNS_API
void adns_processtimeouts(adns_state ads
, const struct timeval
*now
);
633 /* Gives adns flow-of-control so that it can process any timeouts
634 * which might have happened. Very like _processreadable/writeable.
636 * now may be 0; if it isn't, *now must be the current time, recently
637 * obtained from gettimeofday.
640 ADNS_API
void adns_firsttimeout(adns_state ads
,
641 struct timeval
**tv_mod
, struct timeval
*tv_buf
,
643 /* Asks adns when it would first like the opportunity to time
644 * something out. now must be the current time, from gettimeofday.
646 * If tv_mod points to 0 then tv_buf must be non-null, and
647 * _firsttimeout will fill in *tv_buf with the time until the first
648 * timeout, and make *tv_mod point to tv_buf. If adns doesn't have
649 * anything that might need timing out it will leave *tv_mod as 0.
651 * If *tv_mod is not 0 then tv_buf is not used. adns will update
652 * *tv_mod if it has any earlier timeout, and leave it alone if it
655 * This call will not actually do any I/O, or change the fds that adns
656 * is using. It always succeeds and never blocks.
659 ADNS_API
void adns_globalsystemfailure(adns_state ads
);
660 /* If serious problem(s) happen which globally affect your ability to
661 * interact properly with adns, or adns's ability to function
662 * properly, you or adns can call this function.
664 * All currently outstanding queries will be made to fail with
665 * adns_s_systemfail, and adns will close any stream sockets it has
668 * This is used by adns, for example, if gettimeofday() fails.
669 * Without this the program's event loop might start to spin !
671 * This call will never block.
675 * Entrypoints for select-loop based asynch io:
678 ADNS_API
void adns_beforeselect(adns_state ads
, int *maxfd
, fd_set
*readfds
,
679 fd_set
*writefds
, fd_set
*exceptfds
,
680 struct timeval
**tv_mod
, struct timeval
*tv_buf
,
681 const struct timeval
*now
);
682 /* Find out file descriptors adns is interested in, and when it would
683 * like the opportunity to time something out. If you do not plan to
684 * block then tv_mod may be 0. Otherwise, tv_mod and tv_buf are as
685 * for adns_firsttimeout. readfds, writefds, exceptfds and maxfd_io may
688 * If now is not 0 then this will never actually do any I/O, or change
689 * the fds that adns is using or the timeouts it wants. In any case
690 * it won't block, and it will set the timeout to zero if a query
691 * finishes in _beforeselect.
694 ADNS_API
void adns_afterselect(adns_state ads
, int maxfd
, const fd_set
*readfds
,
695 const fd_set
*writefds
, const fd_set
*exceptfds
,
696 const struct timeval
*now
);
697 /* Gives adns flow-of-control for a bit; intended for use after
698 * select. This is just a fancy way of calling adns_processreadable/
699 * writeable/timeouts as appropriate, as if select had returned the
700 * data being passed. Always succeeds.
704 * Example calling sequence:
706 * adns_init _noautosys
712 * adns_submit / adns_check
718 * Entrypoints for poll-loop based asynch io:
722 /* In case your system doesn't have it or you forgot to include
723 * <sys/poll.h>, to stop the following declarations from causing
724 * problems. If your system doesn't have poll then the following
725 * entrypoints will not be defined in libadns. Sorry !
728 ADNS_API
int adns_beforepoll(adns_state ads
, struct pollfd
*fds
, int *nfds_io
, int *timeout_io
,
729 const struct timeval
*now
);
730 /* Finds out which fd's adns is interested in, and when it would like
731 * to be able to time things out. This is in a form suitable for use
734 * On entry, usually fds should point to at least *nfds_io structs.
735 * adns will fill up to that many structs will information for poll,
736 * and record in *nfds_io how many structs it filled. If it wants to
737 * listen for more structs then *nfds_io will be set to the number
738 * required and _beforepoll will return ERANGE.
740 * You may call _beforepoll with fds==0 and *nfds_io 0, in which case
741 * adns will fill in the number of fds that it might be interested in
742 * in *nfds_io, and always return either 0 (if it is not interested in
743 * any fds) or ERANGE (if it is).
745 * NOTE that (unless now is 0) adns may acquire additional fds
746 * from one call to the next, so you must put adns_beforepoll in a
747 * loop, rather than assuming that the second call (with the buffer
748 * size requested by the first) will not return ERANGE.
750 * adns only ever sets POLLIN, POLLOUT and POLLPRI in its pollfd
751 * structs, and only ever looks at those bits. POLLPRI is required to
752 * detect TCP Urgent Data (which should not be used by a DNS server)
753 * so that adns can know that the TCP stream is now useless.
755 * In any case, *timeout_io should be a timeout value as for poll(2),
756 * which adns will modify downwards as required. If the caller does
757 * not plan to block then *timeout_io should be 0 on entry, or
758 * alternatively, timeout_io may be 0. (Alternatively, the caller may
759 * use _beforeselect with timeout_io==0 to find out about file
760 * descriptors, and use _firsttimeout is used to find out when adns
761 * might want to time something out.)
763 * adns_beforepoll will return 0 on success, and will not fail for any
764 * reason other than the fds buffer being too small (ERANGE).
766 * This call will never actually do any I/O. If you supply the
767 * current time it will not change the fds that adns is using or the
770 * In any case this call won't block.
773 #define ADNS_POLLFDS_RECOMMENDED 2
774 /* If you allocate an fds buf with at least RECOMMENDED entries then
775 * you are unlikely to need to enlarge it. You are recommended to do
776 * so if it's convenient. However, you must be prepared for adns to
777 * require more space than this.
780 ADNS_API
void adns_afterpoll(adns_state ads
, const struct pollfd
*fds
, int nfds
,
781 const struct timeval
*now
);
782 /* Gives adns flow-of-control for a bit; intended for use after
783 * poll(2). fds and nfds should be the results from poll(). pollfd
784 * structs mentioning fds not belonging to adns will be ignored.
788 ADNS_API adns_status
adns_rr_info(adns_rrtype type
,
789 const char **rrtname_r
, const char **fmtname_r
,
791 const void *datap
, char **data_r
);
793 * Get information about a query type, or convert reply data to a
794 * textual form. type must be specified, and the official name of the
795 * corresponding RR type will be returned in *rrtname_r, and
796 * information about the processing style in *fmtname_r. The length
797 * of the table entry in an answer for that type will be returned in
798 * in *len_r. Any or all of rrtname_r, fmtname_r and len_r may be 0.
799 * If fmtname_r is non-null then *fmtname_r may be null on return,
800 * indicating that no special processing is involved.
802 * data_r be must be non-null iff datap is. In this case *data_r will
803 * be set to point to a string pointing to a representation of the RR
804 * data in master file format. (The owner name, timeout, class and
805 * type will not be present - only the data part of the RR.) The
806 * memory will have been obtained from malloc() and must be freed by
809 * Usually this routine will succeed. Possible errors include:
811 * adns_s_rrtypeunknown
812 * adns_s_invaliddata (*datap contained garbage)
813 * If an error occurs then no memory has been allocated,
814 * and *rrtname_r, *fmtname_r, *len_r and *data_r are undefined.
816 * There are some adns-invented data formats which are not official
817 * master file formats. These include:
819 * Mailboxes if __qtf_mail822: these are just included as-is.
821 * Addresses (adns_rr_addr): these may be of pretty much any type.
822 * The representation is in two parts: first, a word for the address
823 * family (ie, in AF_XXX, the XXX), and then one or more items for the
824 * address itself, depending on the format. For an IPv4 address the
825 * syntax is INET followed by the dotted quad (from inet_ntoa).
826 * Currently only IPv4 is supported.
828 * Text strings (as in adns_rr_txt) appear inside double quotes, and
829 * use \" and \\ to represent " and \, and \xHH to represent
830 * characters not in the range 32-126.
832 * Hostname with addresses (adns_rr_hostaddr): this consists of the
833 * hostname, as usual, followed by the adns_status value, as an
834 * abbreviation, and then a descriptive string (encoded as if it were
835 * a piece of text), for the address lookup, followed by zero or more
836 * addresses enclosed in ( and ). If the result was a temporary
837 * failure, then a single ? appears instead of the ( ). If the
838 * result was a permanent failure then an empty pair of parentheses
839 * appears (which a space in between). For example, one of the NS
840 * records for greenend.org.uk comes out like
841 * ns.chiark.greenend.org.uk ok "OK" ( INET 195.224.76.132 )
842 * an MX referring to a nonexistent host might come out like:
843 * 50 sun2.nsfnet-relay.ac.uk nxdomain "No such domain" ( )
844 * and if nameserver information is not available you might get:
845 * dns2.spong.dyn.ml.org timeout "DNS query timed out" ?
848 ADNS_API
const char *adns_strerror(adns_status st
);
849 ADNS_API
const char *adns_errabbrev(adns_status st
);
850 ADNS_API
const char *adns_errtypeabbrev(adns_status st
);
851 /* Like strerror but for adns_status values. adns_errabbrev returns
852 * the abbreviation of the error - eg, for adns_s_timeout it returns
853 * "timeout". adns_errtypeabbrev returns the abbreviation of the
854 * error class: ie, for values up to adns_s_max_XXX it will return the
855 * string XXX. You MUST NOT call these functions with status values
856 * not returned by the same adns library.
860 } /* end of extern "C" */