[ADNS] Add function to return number of DNS servers available for query.
[reactos.git] / reactos / sdk / lib / 3rdparty / adns / src / adns.h
1 /*
2 * adns.h
3 * - adns user-visible API (single-threaded, without any locking)
4 */
5 /*
6 *
7 * This file is
8 * Copyright (C) 1997-2000 Ian Jackson <ian@davenant.greenend.org.uk>
9 *
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>
13 *
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)
17 * any later version.
18 *
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.
23 *
24 *
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.
30 *
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.
36 *
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.
46 *
47 *
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.
52 *
53 *
54 */
55
56 #ifndef ADNS_H_INCLUDED
57 #define ADNS_H_INCLUDED
58
59 #ifdef ADNS_JGAA_WIN32
60 # include "adns_win32.h"
61 #else
62 # include <stdio.h>
63 # include <sys/socket.h>
64 # include <netinet/in.h>
65 # include <sys/types.h>
66 # include <sys/time.h>
67 # include <unistd.h>
68
69 # define ADNS_API
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 {}
76 #endif
77
78 #ifdef __cplusplus
79 extern "C" { /* I really dislike this - iwj. */
80 #endif
81
82 /* All struct in_addr anywhere in adns are in NETWORK byte order. */
83
84 typedef struct adns__state *adns_state;
85 typedef struct adns__query *adns_query;
86
87 typedef enum {
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!) */
98 } adns_initflags;
99
100 typedef enum {
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
111 } adns_queryflags;
112
113 typedef enum {
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 */
117
118 adns_r_none= 0,
119
120 adns_r_a= 1,
121
122 adns_r_ns_raw= 2,
123 adns_r_ns= adns_r_ns_raw|adns__qtf_deref,
124
125 adns_r_cname= 5,
126
127 adns_r_soa_raw= 6,
128 adns_r_soa= adns_r_soa_raw|adns__qtf_mail822,
129
130 adns_r_ptr_raw= 12,
131 adns_r_ptr= adns_r_ptr_raw|adns__qtf_deref,
132
133 adns_r_hinfo= 13,
134
135 adns_r_mx_raw= 15,
136 adns_r_mx= adns_r_mx_raw|adns__qtf_deref,
137
138 adns_r_txt= 16,
139
140 adns_r_rp_raw= 17,
141 adns_r_rp= adns_r_rp_raw|adns__qtf_mail822,
142
143 adns_r_addr= adns_r_a|adns__qtf_deref
144
145 } adns_rrtype;
146
147 /*
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).
152 *
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
162 * \DDD otherwise.
163 *
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.)
171 *
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.
177 */
178
179 /*
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.
191 *
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: ! # % ^ & * - _ = + { } .
196 *
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.
206 *
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.
210 *
211 * If no mailbox is supplied the returned string will be `.' in either
212 * case.
213 */
214
215 typedef enum {
216 adns_s_ok,
217
218 /* locally induced errors */
219 adns_s_nomemory,
220 adns_s_unknownrrtype,
221 adns_s_systemfail,
222
223 adns_s_max_localfail= 29,
224
225 /* remotely induced errors, detected locally */
226 adns_s_timeout,
227 adns_s_allservfail,
228 adns_s_norecurse,
229 adns_s_invalidresponse,
230 adns_s_unknownformat,
231
232 adns_s_max_remotefail= 59,
233
234 /* remotely induced errors, reported by remote server to us */
235 adns_s_rcodeservfail,
236 adns_s_rcodeformaterror,
237 adns_s_rcodenotimplemented,
238 adns_s_rcoderefused,
239 adns_s_rcodeunknown,
240
241 adns_s_max_tempfail= 99,
242
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,
248 adns_s_invaliddata,
249
250 adns_s_max_misconfig= 199,
251
252 /* permanent problems with the query */
253 adns_s_querydomainwrong,
254 adns_s_querydomaininvalid,
255 adns_s_querydomaintoolong,
256
257 adns_s_max_misquery= 299,
258
259 /* permanent errors */
260 adns_s_nxdomain,
261 adns_s_nodata,
262
263 adns_s_max_permfail= 499
264
265 } adns_status;
266
267 typedef struct {
268 int len;
269 union {
270 struct sockaddr sa;
271 struct sockaddr_in inet;
272 } addr;
273 } adns_rr_addr;
274
275 typedef struct {
276 char *host;
277 adns_status astatus;
278 int naddrs; /* temp fail => -1, perm fail => 0, s_ok => >0 */
279 adns_rr_addr *addrs;
280 } adns_rr_hostaddr;
281
282 typedef struct {
283 char *(array[2]);
284 } adns_rr_strpair;
285
286 typedef struct {
287 int i;
288 adns_rr_hostaddr ha;
289 } adns_rr_inthostaddr;
290
291 typedef struct {
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).
296 */
297 int i;
298 char *str;
299 } adns_rr_intstr;
300
301 typedef struct {
302 adns_rr_intstr array[2];
303 } adns_rr_intstrpair;
304
305 typedef struct {
306 char *mname, *rname;
307 unsigned long serial, refresh, retry, expire, minimum;
308 } adns_rr_soa;
309
310 typedef struct {
311 adns_status status;
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 */
317 union {
318 void *untyped;
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 */
330 } rrs;
331 } adns_answer;
332
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.
338 * query_io:
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
343 * will all be set.
344 * Errors:
345 * Return values are 0 or an errno value.
346 *
347 * For _init, _init_strcfg, _submit and _synchronous, system errors
348 * (eg, failure to create sockets, malloc failure, etc.) return errno
349 * values.
350 *
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.
356 *
357 * Additionally, _wait can return EINTR if you set adns_if_eintr.
358 *
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
363 * requested.
364 */
365
366 ADNS_API int adns_init(adns_state *newstate_r, adns_initflags flags,
367 FILE *diagfile /*0=>stderr*/);
368
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 state,
372 const char *fn,
373 int lno,
374 const char *buf);
375 ADNS_API int adns_numservers(adns_state state);
376
377 ADNS_API int adns_init_strcfg(adns_state *newstate_r, adns_initflags flags,
378 FILE *diagfile /*0=>discard*/, const char *configtext);
379
380 /* Configuration:
381 * adns_init reads /etc/resolv.conf, which is expected to be (broadly
382 * speaking) in the format expected by libresolv, and then
383 * /etc/resolv-adns.conf if it exists. adns_init_strcfg is instead
384 * passed a string which is interpreted as if it were the contents of
385 * resolv.conf or resolv-adns.conf. In general, configuration which
386 * is set later overrides any that is set earlier.
387 *
388 * Standard directives understood in resolv[-adns].conf:
389 *
390 * nameserver <address>
391 * Must be followed by the IP address of a nameserver. Several
392 * nameservers may be specified, and they will be tried in the order
393 * found. There is a compiled in limit, currently 5, on the number
394 * of nameservers. (libresolv supports only 3 nameservers.)
395 *
396 * search <domain> ...
397 * Specifies the search list for queries which specify
398 * adns_qf_search. This is a list of domains to append to the query
399 * domain. The query domain will be tried as-is either before all
400 * of these or after them, depending on the ndots option setting
401 * (see below).
402 *
403 * domain <domain>
404 * This is present only for backward compatibility with obsolete
405 * versions of libresolv. It should not be used, and is interpreted
406 * by adns as if it were `search' - note that this is subtly
407 * different to libresolv's interpretation of this directive.
408 *
409 * sortlist <addr>/<mask> ...
410 * Should be followed by a sequence of IP-address and netmask pairs,
411 * separated by spaces. They may be specified as
412 * eg. 172.30.206.0/24 or 172.30.206.0/255.255.255.0. Currently up
413 * to 15 pairs may be specified (but note that libresolv only
414 * supports up to 10).
415 *
416 * options
417 * Should followed by one or more options, separated by spaces.
418 * Each option consists of an option name, followed by optionally
419 * a colon and a value. Options are listed below.
420 *
421 * Non-standard directives understood in resolv[-adns].conf:
422 *
423 * clearnameservers
424 * Clears the list of nameservers, so that further nameserver lines
425 * start again from the beginning.
426 *
427 * include <filename>
428 * The specified file will be read.
429 *
430 * Additionally, adns will ignore lines in resolv[-adns].conf which
431 * start with a #.
432 *
433 * Standard options understood:
434 *
435 * debug
436 * Enables debugging output from the resolver, which will be written
437 * to stderr.
438 *
439 * ndots:<count>
440 * Affects whether queries with adns_qf_search will be tried first
441 * without adding domains from the searchlist, or whether the bare
442 * query domain will be tried last. Queries which contain at least
443 * <count> dots will be tried bare first. The default is 1.
444 *
445 * Non-standard options understood:
446 *
447 * adns_checkc:none
448 * adns_checkc:entex
449 * adns_checkc:freq
450 * Changes the consistency checking frequency; this overrides the
451 * setting of adns_if_check_entex, adns_if_check_freq, or neither,
452 * in the flags passed to adns_init.
453 *
454 * There are a number of environment variables which can modify the
455 * behaviour of adns. They take effect only if adns_init is used, and
456 * the caller of adns_init can disable them using adns_if_noenv. In
457 * each case there is both a FOO and an ADNS_FOO; the latter is
458 * interpreted later so that it can override the former. Unless
459 * otherwise stated, environment variables are interpreted after
460 * resolv[-adns].conf are read, in the order they are listed here.
461 *
462 * RES_CONF, ADNS_RES_CONF
463 * A filename, whose contets are in the format of resolv.conf.
464 *
465 * RES_CONF_TEXT, ADNS_RES_CONF_TEXT
466 * A string in the format of resolv.conf.
467 *
468 * RES_OPTIONS, ADNS_RES_OPTIONS
469 * These are parsed as if they appeared in the `options' line of a
470 * resolv.conf. In addition to being parsed at this point in the
471 * sequence, they are also parsed at the very beginning before
472 * resolv.conf or any other environment variables are read, so that
473 * any debug option can affect the processing of the configuration.
474 *
475 * LOCALDOMAIN, ADNS_LOCALDOMAIN
476 * These are interpreted as if their contents appeared in a `search'
477 * line in resolv.conf.
478 */
479
480 ADNS_API int adns_synchronous(adns_state ads,
481 const char *owner,
482 adns_rrtype type,
483 adns_queryflags flags,
484 adns_answer **answer_r);
485
486 /* NB: if you set adns_if_noautosys then _submit and _check do not
487 * make any system calls; you must use some of the asynch-io event
488 * processing functions to actually get things to happen.
489 */
490
491 ADNS_API int adns_submit(adns_state ads,
492 const char *owner,
493 adns_rrtype type,
494 adns_queryflags flags,
495 void *context,
496 adns_query *query_r);
497
498 /* The owner should be quoted in master file format. */
499
500 ADNS_API int adns_check(adns_state ads,
501 adns_query *query_io,
502 adns_answer **answer_r,
503 void **context_r);
504
505 ADNS_API int adns_wait(adns_state ads,
506 adns_query *query_io,
507 adns_answer **answer_r,
508 void **context_r);
509
510 /* same as adns_wait but uses poll(2) internally */
511 ADNS_API int adns_wait_poll(adns_state ads,
512 adns_query *query_io,
513 adns_answer **answer_r,
514 void **context_r);
515
516 ADNS_API void adns_cancel(adns_query query);
517
518 /* The adns_query you get back from _submit is valid (ie, can be
519 * legitimately passed into adns functions) until it is returned by
520 * adns_check or adns_wait, or passed to adns_cancel. After that it
521 * must not be used. You can rely on it not being reused until the
522 * first adns_submit or _transact call using the same adns_state after
523 * it became invalid, so you may compare it for equality with other
524 * query handles until you next call _query or _transact.
525 *
526 * _submit and _synchronous return ENOSYS if they don't understand the
527 * query type.
528 */
529
530 ADNS_API int adns_submit_reverse(adns_state ads,
531 const struct sockaddr *addr,
532 adns_rrtype type,
533 adns_queryflags flags,
534 void *context,
535 adns_query *query_r);
536 /* type must be _r_ptr or _r_ptr_raw. _qf_search is ignored.
537 * addr->sa_family must be AF_INET or you get ENOSYS.
538 */
539
540 ADNS_API int adns_submit_reverse_any(adns_state ads,
541 const struct sockaddr *addr,
542 const char *rzone,
543 adns_rrtype type,
544 adns_queryflags flags,
545 void *context,
546 adns_query *query_r);
547 /* For RBL-style reverse `zone's; look up
548 * <reversed-address>.<zone>
549 * Any type is allowed. _qf_search is ignored.
550 * addr->sa_family must be AF_INET or you get ENOSYS.
551 */
552
553 ADNS_API void adns_finish(adns_state ads);
554 /* You may call this even if you have queries outstanding;
555 * they will be cancelled.
556 */
557
558
559 ADNS_API void adns_forallqueries_begin(adns_state ads);
560 ADNS_API adns_query adns_forallqueries_next(adns_state ads, void **context_r);
561 /* Iterator functions, which you can use to loop over the outstanding
562 * (submitted but not yet successfuly checked/waited) queries.
563 *
564 * You can only have one iteration going at once. You may call _begin
565 * at any time; after that, an iteration will be in progress. You may
566 * only call _next when an iteration is in progress - anything else
567 * may coredump. The iteration remains in progress until _next
568 * returns 0, indicating that all the queries have been walked over,
569 * or ANY other adns function is called with the same adns_state (or a
570 * query in the same adns_state). There is no need to explicitly
571 * finish an iteration.
572 *
573 * context_r may be 0. *context_r may not be set when _next returns 0.
574 */
575
576 ADNS_API void adns_checkconsistency(adns_state ads, adns_query qu);
577 /* Checks the consistency of adns's internal data structures.
578 * If any error is found, the program will abort().
579 * You may pass 0 for qu; if you pass non-null then additional checks
580 * are done to make sure that qu is a valid query.
581 */
582
583 /*
584 * Example expected/legal calling sequence for submit/check/wait:
585 * adns_init
586 * adns_submit 1
587 * adns_submit 2
588 * adns_submit 3
589 * adns_wait 1
590 * adns_check 3 -> EAGAIN
591 * adns_wait 2
592 * adns_wait 3
593 * ....
594 * adns_finish
595 */
596
597 /*
598 * Entrypoints for generic asynch io:
599 * (these entrypoints are not very useful except in combination with *
600 * some of the other I/O model calls which can tell you which fds to
601 * be interested in):
602 *
603 * Note that any adns call may cause adns to open and close fds, so
604 * you must call beforeselect or beforepoll again just before
605 * blocking, or you may not have an up-to-date list of it's fds.
606 */
607
608 ADNS_API int adns_processany(adns_state ads);
609 /* Gives adns flow-of-control for a bit. This will never block, and
610 * can be used with any threading/asynch-io model. If some error
611 * occurred which might cause an event loop to spin then the errno
612 * value is returned.
613 */
614
615 ADNS_API int adns_processreadable(adns_state ads, ADNS_SOCKET fd, const struct timeval *now);
616 ADNS_API int adns_processwriteable(adns_state ads, ADNS_SOCKET fd, const struct timeval *now);
617 ADNS_API int adns_processexceptional(adns_state ads, ADNS_SOCKET fd, const struct timeval *now);
618 /* Gives adns flow-of-control so that it can process incoming data
619 * from, or send outgoing data via, fd. Very like _processany. If it
620 * returns zero then fd will no longer be readable or writeable
621 * (unless of course more data has arrived since). adns will _only_
622 * use that fd and only in the manner specified, regardless of whether
623 * adns_if_noautosys was specified.
624 *
625 * adns_processexceptional should be called when select(2) reports an
626 * exceptional condition, or poll(2) reports POLLPRI.
627 *
628 * It is fine to call _processreabable or _processwriteable when the
629 * fd is not ready, or with an fd that doesn't belong to adns; it will
630 * then just return 0.
631 *
632 * If some error occurred which might prevent an event loop to spin
633 * then the errno value is returned.
634 */
635
636 ADNS_API void adns_processtimeouts(adns_state ads, const struct timeval *now);
637 /* Gives adns flow-of-control so that it can process any timeouts
638 * which might have happened. Very like _processreadable/writeable.
639 *
640 * now may be 0; if it isn't, *now must be the current time, recently
641 * obtained from gettimeofday.
642 */
643
644 ADNS_API void adns_firsttimeout(adns_state ads,
645 struct timeval **tv_mod, struct timeval *tv_buf,
646 struct timeval now);
647 /* Asks adns when it would first like the opportunity to time
648 * something out. now must be the current time, from gettimeofday.
649 *
650 * If tv_mod points to 0 then tv_buf must be non-null, and
651 * _firsttimeout will fill in *tv_buf with the time until the first
652 * timeout, and make *tv_mod point to tv_buf. If adns doesn't have
653 * anything that might need timing out it will leave *tv_mod as 0.
654 *
655 * If *tv_mod is not 0 then tv_buf is not used. adns will update
656 * *tv_mod if it has any earlier timeout, and leave it alone if it
657 * doesn't.
658 *
659 * This call will not actually do any I/O, or change the fds that adns
660 * is using. It always succeeds and never blocks.
661 */
662
663 ADNS_API void adns_globalsystemfailure(adns_state ads);
664 /* If serious problem(s) happen which globally affect your ability to
665 * interact properly with adns, or adns's ability to function
666 * properly, you or adns can call this function.
667 *
668 * All currently outstanding queries will be made to fail with
669 * adns_s_systemfail, and adns will close any stream sockets it has
670 * open.
671 *
672 * This is used by adns, for example, if gettimeofday() fails.
673 * Without this the program's event loop might start to spin !
674 *
675 * This call will never block.
676 */
677
678 /*
679 * Entrypoints for select-loop based asynch io:
680 */
681
682 ADNS_API void adns_beforeselect(adns_state ads, int *maxfd, fd_set *readfds,
683 fd_set *writefds, fd_set *exceptfds,
684 struct timeval **tv_mod, struct timeval *tv_buf,
685 const struct timeval *now);
686 /* Find out file descriptors adns is interested in, and when it would
687 * like the opportunity to time something out. If you do not plan to
688 * block then tv_mod may be 0. Otherwise, tv_mod and tv_buf are as
689 * for adns_firsttimeout. readfds, writefds, exceptfds and maxfd_io may
690 * not be 0.
691 *
692 * If now is not 0 then this will never actually do any I/O, or change
693 * the fds that adns is using or the timeouts it wants. In any case
694 * it won't block, and it will set the timeout to zero if a query
695 * finishes in _beforeselect.
696 */
697
698 ADNS_API void adns_afterselect(adns_state ads, int maxfd, const fd_set *readfds,
699 const fd_set *writefds, const fd_set *exceptfds,
700 const struct timeval *now);
701 /* Gives adns flow-of-control for a bit; intended for use after
702 * select. This is just a fancy way of calling adns_processreadable/
703 * writeable/timeouts as appropriate, as if select had returned the
704 * data being passed. Always succeeds.
705 */
706
707 /*
708 * Example calling sequence:
709 *
710 * adns_init _noautosys
711 * loop {
712 * adns_beforeselect
713 * select
714 * adns_afterselect
715 * ...
716 * adns_submit / adns_check
717 * ...
718 * }
719 */
720
721 /*
722 * Entrypoints for poll-loop based asynch io:
723 */
724
725 struct pollfd;
726 /* In case your system doesn't have it or you forgot to include
727 * <sys/poll.h>, to stop the following declarations from causing
728 * problems. If your system doesn't have poll then the following
729 * entrypoints will not be defined in libadns. Sorry !
730 */
731
732 ADNS_API int adns_beforepoll(adns_state ads, struct pollfd *fds, int *nfds_io, int *timeout_io,
733 const struct timeval *now);
734 /* Finds out which fd's adns is interested in, and when it would like
735 * to be able to time things out. This is in a form suitable for use
736 * with poll(2).
737 *
738 * On entry, usually fds should point to at least *nfds_io structs.
739 * adns will fill up to that many structs will information for poll,
740 * and record in *nfds_io how many structs it filled. If it wants to
741 * listen for more structs then *nfds_io will be set to the number
742 * required and _beforepoll will return ERANGE.
743 *
744 * You may call _beforepoll with fds==0 and *nfds_io 0, in which case
745 * adns will fill in the number of fds that it might be interested in
746 * in *nfds_io, and always return either 0 (if it is not interested in
747 * any fds) or ERANGE (if it is).
748 *
749 * NOTE that (unless now is 0) adns may acquire additional fds
750 * from one call to the next, so you must put adns_beforepoll in a
751 * loop, rather than assuming that the second call (with the buffer
752 * size requested by the first) will not return ERANGE.
753 *
754 * adns only ever sets POLLIN, POLLOUT and POLLPRI in its pollfd
755 * structs, and only ever looks at those bits. POLLPRI is required to
756 * detect TCP Urgent Data (which should not be used by a DNS server)
757 * so that adns can know that the TCP stream is now useless.
758 *
759 * In any case, *timeout_io should be a timeout value as for poll(2),
760 * which adns will modify downwards as required. If the caller does
761 * not plan to block then *timeout_io should be 0 on entry, or
762 * alternatively, timeout_io may be 0. (Alternatively, the caller may
763 * use _beforeselect with timeout_io==0 to find out about file
764 * descriptors, and use _firsttimeout is used to find out when adns
765 * might want to time something out.)
766 *
767 * adns_beforepoll will return 0 on success, and will not fail for any
768 * reason other than the fds buffer being too small (ERANGE).
769 *
770 * This call will never actually do any I/O. If you supply the
771 * current time it will not change the fds that adns is using or the
772 * timeouts it wants.
773 *
774 * In any case this call won't block.
775 */
776
777 #define ADNS_POLLFDS_RECOMMENDED 2
778 /* If you allocate an fds buf with at least RECOMMENDED entries then
779 * you are unlikely to need to enlarge it. You are recommended to do
780 * so if it's convenient. However, you must be prepared for adns to
781 * require more space than this.
782 */
783
784 ADNS_API void adns_afterpoll(adns_state ads, const struct pollfd *fds, int nfds,
785 const struct timeval *now);
786 /* Gives adns flow-of-control for a bit; intended for use after
787 * poll(2). fds and nfds should be the results from poll(). pollfd
788 * structs mentioning fds not belonging to adns will be ignored.
789 */
790
791
792 ADNS_API adns_status adns_rr_info(adns_rrtype type,
793 const char **rrtname_r, const char **fmtname_r,
794 int *len_r,
795 const void *datap, char **data_r);
796 /*
797 * Get information about a query type, or convert reply data to a
798 * textual form. type must be specified, and the official name of the
799 * corresponding RR type will be returned in *rrtname_r, and
800 * information about the processing style in *fmtname_r. The length
801 * of the table entry in an answer for that type will be returned in
802 * in *len_r. Any or all of rrtname_r, fmtname_r and len_r may be 0.
803 * If fmtname_r is non-null then *fmtname_r may be null on return,
804 * indicating that no special processing is involved.
805 *
806 * data_r be must be non-null iff datap is. In this case *data_r will
807 * be set to point to a string pointing to a representation of the RR
808 * data in master file format. (The owner name, timeout, class and
809 * type will not be present - only the data part of the RR.) The
810 * memory will have been obtained from malloc() and must be freed by
811 * the caller.
812 *
813 * Usually this routine will succeed. Possible errors include:
814 * adns_s_nomemory
815 * adns_s_rrtypeunknown
816 * adns_s_invaliddata (*datap contained garbage)
817 * If an error occurs then no memory has been allocated,
818 * and *rrtname_r, *fmtname_r, *len_r and *data_r are undefined.
819 *
820 * There are some adns-invented data formats which are not official
821 * master file formats. These include:
822 *
823 * Mailboxes if __qtf_mail822: these are just included as-is.
824 *
825 * Addresses (adns_rr_addr): these may be of pretty much any type.
826 * The representation is in two parts: first, a word for the address
827 * family (ie, in AF_XXX, the XXX), and then one or more items for the
828 * address itself, depending on the format. For an IPv4 address the
829 * syntax is INET followed by the dotted quad (from inet_ntoa).
830 * Currently only IPv4 is supported.
831 *
832 * Text strings (as in adns_rr_txt) appear inside double quotes, and
833 * use \" and \\ to represent " and \, and \xHH to represent
834 * characters not in the range 32-126.
835 *
836 * Hostname with addresses (adns_rr_hostaddr): this consists of the
837 * hostname, as usual, followed by the adns_status value, as an
838 * abbreviation, and then a descriptive string (encoded as if it were
839 * a piece of text), for the address lookup, followed by zero or more
840 * addresses enclosed in ( and ). If the result was a temporary
841 * failure, then a single ? appears instead of the ( ). If the
842 * result was a permanent failure then an empty pair of parentheses
843 * appears (which a space in between). For example, one of the NS
844 * records for greenend.org.uk comes out like
845 * ns.chiark.greenend.org.uk ok "OK" ( INET 195.224.76.132 )
846 * an MX referring to a nonexistent host might come out like:
847 * 50 sun2.nsfnet-relay.ac.uk nxdomain "No such domain" ( )
848 * and if nameserver information is not available you might get:
849 * dns2.spong.dyn.ml.org timeout "DNS query timed out" ?
850 */
851
852 ADNS_API const char *adns_strerror(adns_status st);
853 ADNS_API const char *adns_errabbrev(adns_status st);
854 ADNS_API const char *adns_errtypeabbrev(adns_status st);
855 /* Like strerror but for adns_status values. adns_errabbrev returns
856 * the abbreviation of the error - eg, for adns_s_timeout it returns
857 * "timeout". adns_errtypeabbrev returns the abbreviation of the
858 * error class: ie, for values up to adns_s_max_XXX it will return the
859 * string XXX. You MUST NOT call these functions with status values
860 * not returned by the same adns library.
861 */
862
863 #ifdef __cplusplus
864 } /* end of extern "C" */
865 #endif
866 #endif