3 * - adns user-visible API
8 * Copyright (C) 1997-2000,2003,2006 Ian Jackson
10 * It is part of adns, which is
11 * Copyright (C) 1997-2000,2003,2006 Ian Jackson
12 * Copyright (C) 1999-2000,2003,2006 Tony Finch
13 * Copyright (C) 1991 Massachusetts Institute of Technology
15 * This program is free software; you can redistribute it and/or modify
16 * it under the terms of the GNU General Public License as published by
17 * the Free Software Foundation; either version 2, or (at your option)
20 * This program is distributed in the hope that it will be useful,
21 * but WITHOUT ANY WARRANTY; without even the implied warranty of
22 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
23 * GNU General Public License for more details.
26 * For the benefit of certain LGPL'd `omnibus' software which
27 * provides a uniform interface to various things including adns, I
28 * make the following additional licence. I do this because the GPL
29 * would otherwise force either the omnibus software to be GPL'd or
30 * the adns-using part to be distributed separately.
32 * So: you may also redistribute and/or modify adns.h (but only the
33 * public header file adns.h and not any other part of adns) under the
34 * terms of the GNU Library General Public License as published by the
35 * Free Software Foundation; either version 2 of the License, or (at
36 * your option) any later version.
38 * Note that adns itself is GPL'd. Authors of adns-using applications
39 * with GPL-incompatible licences, and people who distribute adns with
40 * applications where the whole distribution is not GPL'd, are still
41 * likely to be in violation of the GPL. Anyone who wants to do this
42 * should contact Ian Jackson. Please note that to avoid encouraging
43 * people to infringe the GPL as it applies to the body of adns, Ian
44 * thinks that if you take advantage of the special exception to
45 * redistribute just adns.h under the LGPL, you should retain this
46 * paragraph in its place in the appropriate copyright statements.
49 * You should have received a copy of the GNU General Public License,
50 * or the GNU Library General Public License, as appropriate, along
51 * with this program; if not, write to the Free Software Foundation,
52 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
58 #ifndef ADNS_H_INCLUDED
59 #define ADNS_H_INCLUDED
64 #include <sys/types.h>
65 #include <sys/socket.h>
66 #include <netinet/in.h>
71 extern "C" { /* I really dislike this - iwj. */
74 /* All struct in_addr anywhere in adns are in NETWORK byte order. */
76 typedef struct adns__state
*adns_state
;
77 typedef struct adns__query
*adns_query
;
79 typedef enum { /* In general, or together the desired flags: */
80 adns_if_none
= 0x0000,/* no flags. nicer than 0 for some compilers */
81 adns_if_noenv
= 0x0001,/* do not look at environment */
82 adns_if_noerrprint
= 0x0002,/* never print to stderr (_debug overrides) */
83 adns_if_noserverwarn
=0x0004,/* do not warn to stderr about duff servers etc */
84 adns_if_debug
= 0x0008,/* enable all output to stderr plus debug msgs */
85 adns_if_logpid
= 0x0080,/* include pid in diagnostic output */
86 adns_if_noautosys
= 0x0010,/* do not make syscalls at every opportunity */
87 adns_if_eintr
= 0x0020,/* allow _wait and _synchronous to return EINTR */
88 adns_if_nosigpipe
= 0x0040,/* applic has SIGPIPE ignored, do not protect */
89 adns_if_checkc_entex
=0x0100,/* consistency checks on entry/exit to adns fns */
90 adns_if_checkc_freq
= 0x0300 /* consistency checks very frequently (slow!) */
93 typedef enum { /* In general, or together the desired flags: */
94 adns_qf_none
= 0x00000000,/* no flags */
95 adns_qf_search
= 0x00000001,/* use the searchlist */
96 adns_qf_usevc
= 0x00000002,/* use a virtual circuit (TCP conn) */
97 adns_qf_owner
= 0x00000004,/* fill in the owner field in the answer */
98 adns_qf_quoteok_query
= 0x00000010,/* allow special chars in query domain */
99 adns_qf_quoteok_cname
= 0x00000000,/* ... in CNAME we go via (now default) */
100 adns_qf_quoteok_anshost
=0x00000040,/* ... in things supposedly hostnames */
101 adns_qf_quotefail_cname
=0x00000080,/* refuse if quote-req chars in CNAME we go via */
102 adns_qf_cname_loose
= 0x00000100,/* allow refs to CNAMEs - without, get _s_cname */
103 adns_qf_cname_forbid
= 0x00000200,/* don't follow CNAMEs, instead give _s_cname */
104 adns__qf_internalmask
= 0x0ff00000
108 adns_rrt_typemask
= 0x0ffff,
109 adns__qtf_deref
= 0x10000,/* dereference domains; perhaps get extra data */
110 adns__qtf_mail822
= 0x20000,/* return mailboxes in RFC822 rcpt field fmt */
112 adns_r_unknown
= 0x40000,
113 /* To use this, ask for records of type <rr-type-code>|adns_r_unknown.
114 * adns will not process the RDATA - you'll get adns_rr_byteblocks,
115 * where the int is the length and the unsigned char* points to the
116 * data. String representation of the RR data (by adns_rrinfo) is as in
117 * RFC3597. adns_rr_info will not return the type name in *rrtname_r
118 * (due to memory management problems); *fmtname_r will be set to
121 * Do not specify adns_r_unknown along with a known RR type which
122 * requires domain name uncompression (see RFC3597 s4); domain names
123 * will not be uncompressed and the resulting data would be useless.
124 * Asking for meta-RR types via adns_r_unknown will not work properly
125 * either and may make adns complain about server misbehaviour, so don't
128 * Don't forget adns_qf_quoteok if that's what you want. */
135 adns_r_ns
= adns_r_ns_raw
|adns__qtf_deref
,
140 adns_r_soa
= adns_r_soa_raw
|adns__qtf_mail822
,
142 adns_r_ptr_raw
= 12, /* do not mind PTR with wrong or missing A */
143 adns_r_ptr
= adns_r_ptr_raw
|adns__qtf_deref
,
148 adns_r_mx
= adns_r_mx_raw
|adns__qtf_deref
,
153 adns_r_rp
= adns_r_rp_raw
|adns__qtf_mail822
,
155 /* For SRV records, query domain without _qf_quoteok_query must look
156 * as expected from SRV RFC with hostname-like Name. _With_
157 * _quoteok_query, any query domain is allowed. */
159 adns_r_srv
= adns_r_srv_raw
|adns__qtf_deref
,
161 adns_r_addr
= adns_r_a
|adns__qtf_deref
166 * In queries without qf_quoteok_*, all domains must have standard
167 * legal syntax, or you get adns_s_querydomainvalid (if the query
168 * domain contains bad characters) or adns_s_answerdomaininvalid (if
169 * the answer contains bad characters).
171 * In queries _with_ qf_quoteok_*, domains in the query or response
172 * may contain any characters, quoted according to RFC1035 5.1. On
173 * input to adns, the char* is a pointer to the interior of a "
174 * delimited string, except that " may appear in it unquoted. On
175 * output, the char* is a pointer to a string which would be legal
176 * either inside or outside " delimiters; any character which isn't
177 * legal in a hostname (ie alphanumeric or hyphen) or one of _ / +
178 * (the three other punctuation characters commonly abused in domain
179 * names) will be quoted, as \X if it is a printing ASCII character or
182 * If the query goes via a CNAME then the canonical name (ie, the
183 * thing that the CNAME record refers to) is usually allowed to
184 * contain any characters, which will be quoted as above. With
185 * adns_qf_quotefail_cname you get adns_s_answerdomaininvalid when
186 * this happens. (This is a change from version 0.4 and earlier, in
187 * which failing the query was the default, and you had to say
188 * adns_qf_quoteok_cname to avoid this; that flag is now deprecated.)
190 * In version 0.4 and earlier, asking for _raw records containing
191 * mailboxes without specifying _qf_quoteok_anshost was silly. This
192 * is no longer the case. In this version only parts of responses
193 * that are actually supposed to be hostnames will be refused by
194 * default if quote-requiring characters are found.
198 * If you ask for an RR which contains domains which are actually
199 * encoded mailboxes, and don't ask for the _raw version, then adns
200 * returns the mailbox formatted suitably for an RFC822 recipient
201 * header field. The particular format used is that if the mailbox
202 * requires quoting according to the rules in RFC822 then the
203 * local-part is quoted in double quotes, which end at the next
204 * unescaped double quote (\ is the escape char, and is doubled, and
205 * is used to escape only \ and "). If the local-part is legal
206 * without quoting according to RFC822, it is presented as-is. In any
207 * case the local-part is followed by an @ and the domain. The domain
208 * will not contain any characters not legal in hostnames.
210 * Unquoted local-parts may contain any printing 7-bit ASCII
211 * except the punctuation characters ( ) < > @ , ; : \ " [ ]
212 * I.e. they may contain alphanumerics, and the following
213 * punctuation characters: ! # % ^ & * - _ = + { } .
215 * adns will reject local parts containing control characters (byte
216 * values 0-31, 127-159, and 255) - these appear to be legal according
217 * to RFC822 (at least 0-127) but are clearly a bad idea. RFC1035
218 * syntax does not make any distinction between a single RFC822
219 * quoted-string containing full stops, and a series of quoted-strings
220 * separated by full stops; adns will return anything that isn't all
221 * valid atoms as a single quoted-string. RFC822 does not allow
222 * high-bit-set characters at all, but adns does allow them in
223 * local-parts, treating them as needing quoting.
225 * If you ask for the domain with _raw then _no_ checking is done
226 * (even on the host part, regardless of adns_qf_quoteok_anshost), and
227 * you just get the domain name in master file format.
229 * If no mailbox is supplied the returned string will be `.' in either
236 /* locally induced errors */
238 adns_s_unknownrrtype
,
241 adns_s_max_localfail
= 29,
243 /* remotely induced errors, detected locally */
247 adns_s_invalidresponse
,
248 adns_s_unknownformat
,
250 adns_s_max_remotefail
= 59,
252 /* remotely induced errors, reported by remote server to us */
253 adns_s_rcodeservfail
,
254 adns_s_rcodeformaterror
,
255 adns_s_rcodenotimplemented
,
259 adns_s_max_tempfail
= 99,
261 /* remote configuration errors */
262 adns_s_inconsistent
, /* PTR gives domain whose A does not exist and match */
263 adns_s_prohibitedcname
, /* CNAME, but eg A expected (not if _qf_loosecname) */
264 adns_s_answerdomaininvalid
,
265 adns_s_answerdomaintoolong
,
268 adns_s_max_misconfig
= 199,
270 /* permanent problems with the query */
271 adns_s_querydomainwrong
,
272 adns_s_querydomaininvalid
,
273 adns_s_querydomaintoolong
,
275 adns_s_max_misquery
= 299,
277 /* permanent errors */
281 adns_s_max_permfail
= 499
289 struct sockaddr_in inet
;
296 int naddrs
; /* temp fail => -1, perm fail => 0, s_ok => >0 */
307 } adns_rr_inthostaddr
;
310 /* Used both for mx_raw, in which case i is the preference and str
311 * the domain, and for txt, in which case each entry has i for the
312 * `text' length, and str for the data (which will have had an extra
313 * nul appended so that if it was plain text it is now a
314 * null-terminated string).
321 adns_rr_intstr array
[2];
322 } adns_rr_intstrpair
;
326 unsigned long serial
, refresh
, retry
, expire
, minimum
;
330 int priority
, weight
, port
;
335 int priority
, weight
, port
;
346 char *cname
; /* always NULL if query was for CNAME records */
347 char *owner
; /* only set if req'd in query flags; maybe 0 on error anyway */
348 adns_rrtype type
; /* guaranteed to be same as in query */
349 time_t expires
;/*abs time. def only if _s_ok, nxdomain or nodata. NOT TTL!*/
350 int nrrs
, rrsz
; /* nrrs is 0 if an error occurs */
353 unsigned char *bytes
;
354 char *(*str
); /* ns_raw, cname, ptr, ptr_raw */
355 adns_rr_intstr
*(*manyistr
); /* txt (list strs ends with i=-1, str=0)*/
356 adns_rr_addr
*addr
; /* addr */
357 struct in_addr
*inaddr
; /* a */
358 adns_rr_hostaddr
*hostaddr
; /* ns */
359 adns_rr_intstrpair
*intstrpair
; /* hinfo */
360 adns_rr_strpair
*strpair
; /* rp, rp_raw */
361 adns_rr_inthostaddr
*inthostaddr
;/* mx */
362 adns_rr_intstr
*intstr
; /* mx_raw */
363 adns_rr_soa
*soa
; /* soa, soa_raw */
364 adns_rr_srvraw
*srvraw
; /* srv_raw */
365 adns_rr_srvha
*srvha
;/* srv */
366 adns_rr_byteblock
*byteblock
; /* ...|unknown */
370 /* Memory management:
371 * adns_state and adns_query are actually pointers to malloc'd state;
372 * On submission questions are copied, including the owner domain;
373 * Answers are malloc'd as a single piece of memory; pointers in the
374 * answer struct point into further memory in the answer.
376 * Must always be non-null pointer;
377 * If *query_io is 0 to start with then any query may be returned;
378 * If *query_io is !0 adns_query then only that query may be returned.
379 * If the call is successful, *query_io, *answer_r, and *context_r
382 * Return values are 0 or an errno value.
384 * For _init, _init_strcfg, _submit and _synchronous, system errors
385 * (eg, failure to create sockets, malloc failure, etc.) return errno
386 * values. EINVAL from _init et al means the configuration file
387 * is erroneous and cannot be parsed.
389 * For _wait and _check failures are reported in the answer
390 * structure, and only 0, ESRCH or (for _check) EAGAIN is
391 * returned: if no (appropriate) requests are done adns_check returns
392 * EAGAIN; if no (appropriate) requests are outstanding both
393 * adns_query and adns_wait return ESRCH.
395 * Additionally, _wait can return EINTR if you set adns_if_eintr.
397 * All other errors (nameserver failure, timed out connections, &c)
398 * are returned in the status field of the answer. After a
399 * successful _wait or _check, if status is nonzero then nrrs will be
400 * 0, otherwise it will be >0. type will always be the type
405 * adns does not use any static modifiable state, so it
406 * is safe to call adns_init several times and then use the
407 * resulting adns_states concurrently.
408 * However, it is NOT safe to make simultaneous calls into
409 * adns using the same adns_state; a single adns_state must be used
410 * only by one thread at a time. You can solve this problem by
411 * having one adns_state per thread, or if that isn't feasible, you
412 * could maintain a pool of adns_states. Unfortunately neither of
413 * these approaches has optimal performance.
416 int adns_init(adns_state
*newstate_r
, adns_initflags flags
,
417 FILE *diagfile
/*0=>stderr*/);
419 int adns_init_strcfg(adns_state
*newstate_r
, adns_initflags flags
,
420 FILE *diagfile
/*0=>discard*/, const char *configtext
);
422 typedef void adns_logcallbackfn(adns_state ads
, void *logfndata
,
423 const char *fmt
, va_list al
);
424 /* Will be called perhaps several times for each message; when the
425 * message is complete, the string implied by fmt and al will end in
426 * a newline. Log messages start with `adns debug:' or `adns
427 * warning:' or `adns:' (for errors), or `adns debug [PID]:'
428 * etc. if adns_if_logpid is set. */
430 int adns_init_logfn(adns_state
*newstate_r
, adns_initflags flags
,
431 const char *configtext
/*0=>use default config files*/,
432 adns_logcallbackfn
*logfn
/*0=>logfndata is a FILE* */,
433 void *logfndata
/*0 with logfn==0 => discard*/);
436 * adns_init reads /etc/resolv.conf, which is expected to be (broadly
437 * speaking) in the format expected by libresolv, and then
438 * /etc/resolv-adns.conf if it exists. adns_init_strcfg is instead
439 * passed a string which is interpreted as if it were the contents of
440 * resolv.conf or resolv-adns.conf. In general, configuration which
441 * is set later overrides any that is set earlier.
443 * Standard directives understood in resolv[-adns].conf:
445 * nameserver <address>
446 * Must be followed by the IP address of a nameserver. Several
447 * nameservers may be specified, and they will be tried in the order
448 * found. There is a compiled in limit, currently 5, on the number
449 * of nameservers. (libresolv supports only 3 nameservers.)
451 * search <domain> ...
452 * Specifies the search list for queries which specify
453 * adns_qf_search. This is a list of domains to append to the query
454 * domain. The query domain will be tried as-is either before all
455 * of these or after them, depending on the ndots option setting
459 * This is present only for backward compatibility with obsolete
460 * versions of libresolv. It should not be used, and is interpreted
461 * by adns as if it were `search' - note that this is subtly
462 * different to libresolv's interpretation of this directive.
464 * sortlist <addr>/<mask> ...
465 * Should be followed by a sequence of IP-address and netmask pairs,
466 * separated by spaces. They may be specified as
467 * eg. 172.30.206.0/24 or 172.30.206.0/255.255.255.0. Currently up
468 * to 15 pairs may be specified (but note that libresolv only
469 * supports up to 10).
472 * Should followed by one or more options, separated by spaces.
473 * Each option consists of an option name, followed by optionally
474 * a colon and a value. Options are listed below.
476 * Non-standard directives understood in resolv[-adns].conf:
479 * Clears the list of nameservers, so that further nameserver lines
480 * start again from the beginning.
483 * The specified file will be read.
485 * Additionally, adns will ignore lines in resolv[-adns].conf which
488 * Standard options understood:
491 * Enables debugging output from the resolver, which will be written
495 * Affects whether queries with adns_qf_search will be tried first
496 * without adding domains from the searchlist, or whether the bare
497 * query domain will be tried last. Queries which contain at least
498 * <count> dots will be tried bare first. The default is 1.
500 * Non-standard options understood:
505 * Changes the consistency checking frequency; this overrides the
506 * setting of adns_if_check_entex, adns_if_check_freq, or neither,
507 * in the flags passed to adns_init.
509 * There are a number of environment variables which can modify the
510 * behaviour of adns. They take effect only if adns_init is used, and
511 * the caller of adns_init can disable them using adns_if_noenv. In
512 * each case there is both a FOO and an ADNS_FOO; the latter is
513 * interpreted later so that it can override the former. Unless
514 * otherwise stated, environment variables are interpreted after
515 * resolv[-adns].conf are read, in the order they are listed here.
517 * RES_CONF, ADNS_RES_CONF
518 * A filename, whose contets are in the format of resolv.conf.
520 * RES_CONF_TEXT, ADNS_RES_CONF_TEXT
521 * A string in the format of resolv.conf.
523 * RES_OPTIONS, ADNS_RES_OPTIONS
524 * These are parsed as if they appeared in the `options' line of a
525 * resolv.conf. In addition to being parsed at this point in the
526 * sequence, they are also parsed at the very beginning before
527 * resolv.conf or any other environment variables are read, so that
528 * any debug option can affect the processing of the configuration.
530 * LOCALDOMAIN, ADNS_LOCALDOMAIN
531 * These are interpreted as if their contents appeared in a `search'
532 * line in resolv.conf.
535 int adns_synchronous(adns_state ads
,
538 adns_queryflags flags
,
539 adns_answer
**answer_r
);
541 /* NB: if you set adns_if_noautosys then _submit and _check do not
542 * make any system calls; you must use some of the asynch-io event
543 * processing functions to actually get things to happen.
546 int adns_submit(adns_state ads
,
549 adns_queryflags flags
,
551 adns_query
*query_r
);
553 /* The owner should be quoted in master file format. */
555 int adns_check(adns_state ads
,
556 adns_query
*query_io
,
557 adns_answer
**answer_r
,
560 int adns_wait(adns_state ads
,
561 adns_query
*query_io
,
562 adns_answer
**answer_r
,
565 /* same as adns_wait but uses poll(2) internally */
566 int adns_wait_poll(adns_state ads
,
567 adns_query
*query_io
,
568 adns_answer
**answer_r
,
571 void adns_cancel(adns_query query
);
573 /* The adns_query you get back from _submit is valid (ie, can be
574 * legitimately passed into adns functions) until it is returned by
575 * adns_check or adns_wait, or passed to adns_cancel. After that it
576 * must not be used. You can rely on it not being reused until the
577 * first adns_submit or _transact call using the same adns_state after
578 * it became invalid, so you may compare it for equality with other
579 * query handles until you next call _query or _transact.
581 * _submit and _synchronous return ENOSYS if they don't understand the
585 int adns_submit_reverse(adns_state ads
,
586 const struct sockaddr
*addr
,
588 adns_queryflags flags
,
590 adns_query
*query_r
);
591 /* type must be _r_ptr or _r_ptr_raw. _qf_search is ignored.
592 * addr->sa_family must be AF_INET or you get ENOSYS.
595 int adns_submit_reverse_any(adns_state ads
,
596 const struct sockaddr
*addr
,
599 adns_queryflags flags
,
601 adns_query
*query_r
);
602 /* For RBL-style reverse `zone's; look up
603 * <reversed-address>.<zone>
604 * Any type is allowed. _qf_search is ignored.
605 * addr->sa_family must be AF_INET or you get ENOSYS.
608 void adns_finish(adns_state ads
);
609 /* You may call this even if you have queries outstanding;
610 * they will be cancelled.
614 void adns_forallqueries_begin(adns_state ads
);
615 adns_query
adns_forallqueries_next(adns_state ads
, void **context_r
);
616 /* Iterator functions, which you can use to loop over the outstanding
617 * (submitted but not yet successfuly checked/waited) queries.
619 * You can only have one iteration going at once. You may call _begin
620 * at any time; after that, an iteration will be in progress. You may
621 * only call _next when an iteration is in progress - anything else
622 * may coredump. The iteration remains in progress until _next
623 * returns 0, indicating that all the queries have been walked over,
624 * or ANY other adns function is called with the same adns_state (or a
625 * query in the same adns_state). There is no need to explicitly
626 * finish an iteration.
628 * context_r may be 0. *context_r may not be set when _next returns 0.
631 void adns_checkconsistency(adns_state ads
, adns_query qu
);
632 /* Checks the consistency of adns's internal data structures.
633 * If any error is found, the program will abort().
634 * You may pass 0 for qu; if you pass non-null then additional checks
635 * are done to make sure that qu is a valid query.
639 * Example expected/legal calling sequence for submit/check/wait:
645 * adns_check 3 -> EAGAIN
653 * Entrypoints for generic asynch io:
654 * (these entrypoints are not very useful except in combination with *
655 * some of the other I/O model calls which can tell you which fds to
658 * Note that any adns call may cause adns to open and close fds, so
659 * you must call beforeselect or beforepoll again just before
660 * blocking, or you may not have an up-to-date list of it's fds.
663 int adns_processany(adns_state ads
);
664 /* Gives adns flow-of-control for a bit. This will never block, and
665 * can be used with any threading/asynch-io model. If some error
666 * occurred which might cause an event loop to spin then the errno
670 int adns_processreadable(adns_state ads
, int fd
, const struct timeval
*now
);
671 int adns_processwriteable(adns_state ads
, int fd
, const struct timeval
*now
);
672 int adns_processexceptional(adns_state ads
, int fd
, const struct timeval
*now
);
673 /* Gives adns flow-of-control so that it can process incoming data
674 * from, or send outgoing data via, fd. Very like _processany. If it
675 * returns zero then fd will no longer be readable or writeable
676 * (unless of course more data has arrived since). adns will _only_
677 * use that fd and only in the manner specified, regardless of whether
678 * adns_if_noautosys was specified.
680 * adns_processexceptional should be called when select(2) reports an
681 * exceptional condition, or poll(2) reports POLLPRI.
683 * It is fine to call _processreabable or _processwriteable when the
684 * fd is not ready, or with an fd that doesn't belong to adns; it will
685 * then just return 0.
687 * If some error occurred which might prevent an event loop to spin
688 * then the errno value is returned.
691 void adns_processtimeouts(adns_state ads
, const struct timeval
*now
);
692 /* Gives adns flow-of-control so that it can process any timeouts
693 * which might have happened. Very like _processreadable/writeable.
695 * now may be 0; if it isn't, *now must be the current time, recently
696 * obtained from gettimeofday.
699 void adns_firsttimeout(adns_state ads
,
700 struct timeval
**tv_mod
, struct timeval
*tv_buf
,
702 /* Asks adns when it would first like the opportunity to time
703 * something out. now must be the current time, from gettimeofday.
705 * If tv_mod points to 0 then tv_buf must be non-null, and
706 * _firsttimeout will fill in *tv_buf with the time until the first
707 * timeout, and make *tv_mod point to tv_buf. If adns doesn't have
708 * anything that might need timing out it will leave *tv_mod as 0.
710 * If *tv_mod is not 0 then tv_buf is not used. adns will update
711 * *tv_mod if it has any earlier timeout, and leave it alone if it
714 * This call will not actually do any I/O, or change the fds that adns
715 * is using. It always succeeds and never blocks.
718 void adns_globalsystemfailure(adns_state ads
);
719 /* If serious problem(s) happen which globally affect your ability to
720 * interact properly with adns, or adns's ability to function
721 * properly, you or adns can call this function.
723 * All currently outstanding queries will be made to fail with
724 * adns_s_systemfail, and adns will close any stream sockets it has
727 * This is used by adns, for example, if gettimeofday() fails.
728 * Without this the program's event loop might start to spin !
730 * This call will never block.
734 * Entrypoints for select-loop based asynch io:
737 void adns_beforeselect(adns_state ads
, int *maxfd
, fd_set
*readfds
,
738 fd_set
*writefds
, fd_set
*exceptfds
,
739 struct timeval
**tv_mod
, struct timeval
*tv_buf
,
740 const struct timeval
*now
);
741 /* Find out file descriptors adns is interested in, and when it would
742 * like the opportunity to time something out. If you do not plan to
743 * block then tv_mod may be 0. Otherwise, tv_mod and tv_buf are as
744 * for adns_firsttimeout. readfds, writefds, exceptfds and maxfd_io may
747 * If tv_mod is 0 on entry then this will never actually do any I/O,
748 * or change the fds that adns is using or the timeouts it wants. In
749 * any case it won't block, and it will set the timeout to zero if a
750 * query finishes in _beforeselect.
753 void adns_afterselect(adns_state ads
, int maxfd
, const fd_set
*readfds
,
754 const fd_set
*writefds
, const fd_set
*exceptfds
,
755 const struct timeval
*now
);
756 /* Gives adns flow-of-control for a bit; intended for use after
757 * select. This is just a fancy way of calling adns_processreadable/
758 * writeable/timeouts as appropriate, as if select had returned the
759 * data being passed. Always succeeds.
763 * Example calling sequence:
765 * adns_init _noautosys
771 * adns_submit / adns_check
777 * Entrypoints for poll-loop based asynch io:
781 /* In case your system doesn't have it or you forgot to include
782 * <sys/poll.h>, to stop the following declarations from causing
783 * problems. If your system doesn't have poll then the following
784 * entrypoints will not be defined in libadns. Sorry !
787 int adns_beforepoll(adns_state ads
, struct pollfd
*fds
,
788 int *nfds_io
, int *timeout_io
,
789 const struct timeval
*now
);
790 /* Finds out which fd's adns is interested in, and when it would like
791 * to be able to time things out. This is in a form suitable for use
794 * On entry, usually fds should point to at least *nfds_io structs.
795 * adns will fill up to that many structs will information for poll,
796 * and record in *nfds_io how many structs it filled. If it wants to
797 * listen for more structs then *nfds_io will be set to the number
798 * required and _beforepoll will return ERANGE.
800 * You may call _beforepoll with fds==0 and *nfds_io 0, in which case
801 * adns will fill in the number of fds that it might be interested in
802 * in *nfds_io, and always return either 0 (if it is not interested in
803 * any fds) or ERANGE (if it is).
805 * NOTE that (unless now is 0) adns may acquire additional fds
806 * from one call to the next, so you must put adns_beforepoll in a
807 * loop, rather than assuming that the second call (with the buffer
808 * size requested by the first) will not return ERANGE.
810 * adns only ever sets POLLIN, POLLOUT and POLLPRI in its pollfd
811 * structs, and only ever looks at those bits. POLLPRI is required to
812 * detect TCP Urgent Data (which should not be used by a DNS server)
813 * so that adns can know that the TCP stream is now useless.
815 * In any case, *timeout_io should be a timeout value as for poll(2),
816 * which adns will modify downwards as required. If the caller does
817 * not plan to block then *timeout_io should be 0 on entry, or
818 * alternatively, timeout_io may be 0. (Alternatively, the caller may
819 * use _beforeselect with timeout_io==0 to find out about file
820 * descriptors, and use _firsttimeout is used to find out when adns
821 * might want to time something out.)
823 * adns_beforepoll will return 0 on success, and will not fail for any
824 * reason other than the fds buffer being too small (ERANGE).
826 * This call will never actually do any I/O. If you supply the
827 * current time it will not change the fds that adns is using or the
830 * In any case this call won't block.
833 #define ADNS_POLLFDS_RECOMMENDED 2
834 /* If you allocate an fds buf with at least RECOMMENDED entries then
835 * you are unlikely to need to enlarge it. You are recommended to do
836 * so if it's convenient. However, you must be prepared for adns to
837 * require more space than this.
840 void adns_afterpoll(adns_state ads
, const struct pollfd
*fds
, int nfds
,
841 const struct timeval
*now
);
842 /* Gives adns flow-of-control for a bit; intended for use after
843 * poll(2). fds and nfds should be the results from poll(). pollfd
844 * structs mentioning fds not belonging to adns will be ignored.
848 adns_status
adns_rr_info(adns_rrtype type
,
849 const char **rrtname_r
, const char **fmtname_r
,
851 const void *datap
, char **data_r
);
853 * Get information about a query type, or convert reply data to a
854 * textual form. type must be specified, and the official name of the
855 * corresponding RR type will be returned in *rrtname_r, and
856 * information about the processing style in *fmtname_r. The length
857 * of the table entry in an answer for that type will be returned in
858 * in *len_r. Any or all of rrtname_r, fmtname_r and len_r may be 0.
859 * If fmtname_r is non-null then *fmtname_r may be null on return,
860 * indicating that no special processing is involved.
862 * data_r be must be non-null iff datap is. In this case *data_r will
863 * be set to point to a string pointing to a representation of the RR
864 * data in master file format. (The owner name, timeout, class and
865 * type will not be present - only the data part of the RR.) The
866 * memory will have been obtained from malloc() and must be freed by
869 * Usually this routine will succeed. Possible errors include:
871 * adns_s_rrtypeunknown
872 * adns_s_invaliddata (*datap contained garbage)
873 * If an error occurs then no memory has been allocated,
874 * and *rrtname_r, *fmtname_r, *len_r and *data_r are undefined.
876 * There are some adns-invented data formats which are not official
877 * master file formats. These include:
879 * Mailboxes if __qtf_mail822: these are just included as-is.
881 * Addresses (adns_rr_addr): these may be of pretty much any type.
882 * The representation is in two parts: first, a word for the address
883 * family (ie, in AF_XXX, the XXX), and then one or more items for the
884 * address itself, depending on the format. For an IPv4 address the
885 * syntax is INET followed by the dotted quad (from inet_ntoa).
886 * Currently only IPv4 is supported.
888 * Text strings (as in adns_rr_txt) appear inside double quotes, and
889 * use \" and \\ to represent " and \, and \xHH to represent
890 * characters not in the range 32-126.
892 * Hostname with addresses (adns_rr_hostaddr): this consists of the
893 * hostname, as usual, followed by the adns_status value, as an
894 * abbreviation, and then a descriptive string (encoded as if it were
895 * a piece of text), for the address lookup, followed by zero or more
896 * addresses enclosed in ( and ). If the result was a temporary
897 * failure, then a single ? appears instead of the ( ). If the
898 * result was a permanent failure then an empty pair of parentheses
899 * appears (which a space in between). For example, one of the NS
900 * records for greenend.org.uk comes out like
901 * ns.chiark.greenend.org.uk ok "OK" ( INET 195.224.76.132 )
902 * an MX referring to a nonexistent host might come out like:
903 * 50 sun2.nsfnet-relay.ac.uk nxdomain "No such domain" ( )
904 * and if nameserver information is not available you might get:
905 * dns2.spong.dyn.ml.org timeout "DNS query timed out" ?
908 const char *adns_strerror(adns_status st
);
909 const char *adns_errabbrev(adns_status st
);
910 const char *adns_errtypeabbrev(adns_status st
);
911 /* Like strerror but for adns_status values. adns_errabbrev returns
912 * the abbreviation of the error - eg, for adns_s_timeout it returns
913 * "timeout". adns_errtypeabbrev returns the abbreviation of the
914 * error class: ie, for values up to adns_s_max_XXX it will return the
915 * string XXX. You MUST NOT call these functions with status values
916 * not returned by the same adns library.
920 } /* end of extern "C" */