Embryonic IPv6 support.
[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) 1997-1999 Ian Jackson <ian@davenant.greenend.org.uk>
9 *
10 * It is part of adns, which is
11 * Copyright (C) 1997-1999 Ian Jackson <ian@davenant.greenend.org.uk>
12 * Copyright (C) 1999 Tony Finch <dot@dotat.at>
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 provides
26 * a uniform interface to various things including adns, I make the
27 * following additional licence. I do this because the GPL would
28 * otherwise force either the omnibus software to be GPL'd or for the
29 * adns-using part to be distributed separately.
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 the body of adns, I think
43 * that if you take advantage of the special exception to redistribute
44 * just adns.h under the LGPL, you should retain this paragraph in its
45 * place in the appropriate copyright statements.
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 * $Id$
55 */
56
57 #ifndef ADNS_H_INCLUDED
58 #define ADNS_H_INCLUDED
59 #ifdef __cplusplus
60 extern "C" { /* I really dislike this - iwj. */
61 #endif
62
63 #include <stdio.h>
64
65 #include <sys/socket.h>
66 #include <netinet/in.h>
67 #include <sys/types.h>
68 #include <sys/time.h>
69 #include <unistd.h>
70
71 #ifndef AF_INET6
72 #include "adns-in6fake.h"
73 #endif
74
75 /* All struct in_addr anywhere in adns are in NETWORK byte order. */
76
77 typedef struct adns__state *adns_state;
78 typedef struct adns__query *adns_query;
79
80 typedef enum {
81 adns_if_noenv= 0x0001, /* do not look at environment */
82 adns_if_noerrprint= 0x0002, /* never print output to stderr (_debug overrides) */
83 adns_if_noserverwarn= 0x0004, /* do not warn to stderr about duff nameservers 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 set to SIG_IGN, do not protect */
89 adns_if_checkc_entex= 0x0100, /* do consistency checks on entry/exit to adns funcs */
90 adns_if_checkc_freq= 0x0300 /* do consistency checks very frequently (slow!) */
91 adns_if_ip6= 0x1000 /* make default be adns_qf_ip6 */
92 } adns_initflags;
93
94 typedef enum {
95 adns_qf_search= 0x00000001, /* use the searchlist */
96 adns_qf_usevc= 0x00000002, /* use a virtual circuit (TCP connection) */
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, /* allow ... in CNAME we go via - now default */
100 adns_qf_quoteok_anshost= 0x00000040, /* allow ... in things supposed to be 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_ip6= 0x00001000, /* return addrs as AF_INET6 in all cases */
105 adns_qf_ip6mixed= 0x00002000, /* return mixture of AF_INET4 and AF_INET6 */
106 adns_qf_ip4= 0x00003000, /* never return AF_INET6, even with _if_ip6 */
107 adns__qf_internalmask= 0x0ff00000
108 } adns_queryflags;
109
110 /* IPv6 support:
111 * adns_if_ip6 has the effect of changing the default from
112 * adns_qf_ip4 to adns_qf_ip6.
113 *
114 * query type _qf__ip4 _qf_ip6mixed _qf_ip6
115 *
116 * _r_addr A? => AF_INET AAAA? => AF_INET6 AAAA? => AF_INET6
117 * else fail else A? => AF_INET else A? => AF_INET6
118 *
119 * _r_a A => AF_INET A => AF_INET A => AF_INET6
120 *
121 * _r_aaaa AAAA => AF_INET6 AAAA => AF_INET6 AAAA => AF_INET6
122 *
123 * Ie,
124 * _ip4: only A lookups will be done, and everything is
125 * returned as AF_INET addresses;
126 * _ip6mixed: will look for AAAA records first, and if there
127 * are any, return them as AF_INET6, otherwise like _ip4.
128 * _ip6: like _ip6mixed, but will return even IPv4 addresses in
129 * IPv6-mapped form inside AF_INET6, for all query types.
130 *
131 * Furthermore, there are configuration options which can prevent the
132 * use of either AAAA or A records for _r_addr; so it is safe to use
133 * _qf_ip6 and _r_addr without checking explicitly whether the host
134 * has IPv6 connectivity.
135 *
136 * Applications which do not support IPv4 should set none of these
137 * flags. Applications which have been `naively' converted to use
138 * AF_INET6 throughout should set adns_if_ip6. Applications which
139 * know what they are doing should know which flags to set :-).
140 */
141
142 typedef enum {
143 adns__rrt_typemask= 0x0ffff,
144 adns__qtf_deref= 0x10000, /* dereference domains and perhaps produce extra data */
145 adns__qtf_mail822= 0x20000, /* make mailboxes be in RFC822 rcpt field format */
146
147 adns_r_none= 0,
148
149 adns_r_a= 1,
150
151 adns_r_ns_raw= 2,
152 adns_r_ns= adns_r_ns_raw|adns__qtf_deref,
153
154 adns_r_cname= 5,
155
156 adns_r_soa_raw= 6,
157 adns_r_soa= adns_r_soa_raw|adns__qtf_mail822,
158
159 adns_r_ptr_raw= 12,
160 adns_r_ptr= adns_r_ptr_raw|adns__qtf_deref,
161
162 adns_r_hinfo= 13,
163
164 adns_r_mx_raw= 15,
165 adns_r_mx= adns_r_mx_raw|adns__qtf_deref,
166
167 adns_r_txt= 16,
168
169 adns_r_rp_raw= 17,
170 adns_r_rp= adns_r_rp_raw|adns__qtf_mail822,
171
172 adns_r_aaaa= 28,
173
174 adns_r_srv_raw= 33,
175 adns_r_srv= adns_r_srv_raw|adns__qtf_deref,
176
177 adns_r_addr= adns_r_a|adns__qtf_deref
178
179 } adns_rrtype;
180
181 /*
182 * In queries without qf_quoteok_*, all domains must have standard
183 * legal syntax, or you get adns_s_querydomainvalid (if the query
184 * domain contains bad characters) or adns_s_answerdomaininvalid (if
185 * the answer contains bad characters).
186 *
187 * In queries _with_ qf_quoteok_*, domains in the query or response
188 * may contain any characters, quoted according to RFC1035 5.1. On
189 * input to adns, the char* is a pointer to the interior of a "
190 * delimited string, except that " may appear in it unquoted. On
191 * output, the char* is a pointer to a string which would be legal
192 * either inside or outside " delimiters; any character which isn't
193 * legal in a hostname (ie alphanumeric or hyphen) or one of _ / +
194 * (the three other punctuation characters commonly abused in domain
195 * names) will be quoted, as \X if it is a printing ASCII character or
196 * \DDD otherwise.
197 *
198 * (The characters which will be unquoted are the printing 7-bit ASCII
199 * characters except the punctuation characters " ( ) @ ; $ \
200
201 * I.e. unquoted characters are alphanumerics, and the following
202 * punctuation characters: ! # % ^ & * - _ = + [ ] { }
203 *
204 * If the query goes via a CNAME then the canonical name (ie, the
205 * thing that the CNAME record refers to) is usually allowed to
206 * contain any characters, which will be quoted as above. With
207 * adns_qf_quotefail_cname you get adns_s_answerdomaininvalid when
208 * this happens. (This is a change from version 0.4 and earlier, in
209 * which failing the query was the default, and you had to say
210 * adns_qf_quoteok_cname to avoid this; that flag is now deprecated.)
211 *
212 * In version 0.4 and earlier, asking for _raw records containing
213 * mailboxes without specifying _qf_quoteok_anshost was silly. This
214 * is no longer the case. In this version only parts of responses
215 * that are actually supposed to be hostnames will be refused by
216 * default if quote-requiring characters are found.
217 */
218
219 /*
220 * If you ask for an RR which contains domains which are actually
221 * encoded mailboxes, and don't ask for the _raw version, then adns
222 * returns the mailbox formatted suitably for an RFC822 recipient
223 * header field. The particular format used is that if the mailbox
224 * requires quoting according to the rules in RFC822 then the
225 * local-part is quoted in double quotes, which end at the next
226 * unescaped double quote. (\ is the escape char, and is doubled, and
227 * is used to escape only \ and ".) Otherwise the local-part is
228 * presented as-is. In any case this is followed by an @ and the
229 * domain. The domain will not contain any characters not legal in
230 * hostnames. adns will protect the application from local parts
231 * containing control characters - these appear to be legal according
232 * to RFC822 but are clearly a bad idea.
233 *
234 * If you ask for the domain with _raw then _no_ checking is done
235 * (even on the host part, regardless of adns_qf_quoteok_anshost), and
236 * you just get the domain name in master file format.
237 *
238 * If no mailbox is supplied the returned string will be `.' in either
239 * caswe.
240 */
241
242 typedef enum {
243 adns_s_ok,
244
245 /* locally induced errors */
246 adns_s_nomemory,
247 adns_s_unknownrrtype,
248 adns_s_systemfail,
249
250 adns_s_max_localfail= 29,
251
252 /* remotely induced errors, detected locally */
253 adns_s_timeout,
254 adns_s_allservfail,
255 adns_s_norecurse,
256 adns_s_invalidresponse,
257 adns_s_unknownformat,
258
259 adns_s_max_remotefail= 59,
260
261 /* remotely induced errors, reported by remote server to us */
262 adns_s_rcodeservfail,
263 adns_s_rcodeformaterror,
264 adns_s_rcodenotimplemented,
265 adns_s_rcoderefused,
266 adns_s_rcodeunknown,
267
268 adns_s_max_tempfail= 99,
269
270 /* remote configuration errors */
271 adns_s_inconsistent, /* PTR gives domain whose A does not exist and match */
272 adns_s_prohibitedcname, /* CNAME found where eg A expected (not if _qf_loosecname) */
273 adns_s_answerdomaininvalid,
274 adns_s_answerdomaintoolong,
275 adns_s_invaliddata,
276
277 adns_s_max_misconfig= 199,
278
279 /* permanent problems with the query */
280 adns_s_querydomainwrong,
281 adns_s_querydomaininvalid,
282 adns_s_querydomaintoolong,
283
284 adns_s_max_misquery= 299,
285
286 /* permanent errors */
287 adns_s_nxdomain,
288 adns_s_nodata,
289
290 adns_s_max_permfail= 499
291
292 } adns_status;
293
294 typedef struct {
295 int len;
296 union {
297 struct sockaddr sa;
298 struct sockaddr_in inet;
299 struct sockaddr_in6 inet6;
300 } addr;
301 } adns_rr_addr;
302
303 typedef struct {
304 char *host;
305 adns_status astatus;
306 int naddrs; /* temp fail => -1, perm fail => 0, s_ok => >0 */
307 adns_rr_addr *addrs;
308 } adns_rr_hostaddr;
309
310 typedef struct {
311 char *(array[2]);
312 } adns_rr_strpair;
313
314 typedef struct {
315 int i;
316 adns_rr_hostaddr ha;
317 } adns_rr_inthostaddr;
318
319 typedef struct {
320 /* Used both for mx_raw, in which case i is the preference and str the domain,
321 * and for txt, in which case each entry has i for the `text' length,
322 * and str for the data (which will have had an extra nul appended
323 * so that if it was plain text it is now a null-terminated string).
324 */
325 int i;
326 char *str;
327 } adns_rr_intstr;
328
329 typedef struct {
330 adns_rr_intstr array[2];
331 } adns_rr_intstrpair;
332
333 typedef struct {
334 char *mname, *rname;
335 unsigned long serial, refresh, retry, expire, minimum;
336 } adns_rr_soa;
337
338 typedef struct {
339 unsigned short priority;
340 unsigned short weight;
341 unsigned short port;
342 adns_rr_hostaddr ha;
343 } adns_rr_srv;
344
345 typedef struct {
346 unsigned short priority;
347 unsigned short weight;
348 unsigned short port;
349 char *target;
350 } adns_rr_srvraw;
351
352 typedef struct {
353 adns_status status;
354 char *cname; /* always NULL if query was for CNAME records */
355 char *owner; /* only set if requested in query flags, and may be 0 on error anyway */
356 adns_rrtype type; /* guaranteed to be same as in query */
357 time_t expires; /* expiry time, defined only if _s_ok, nxdomain or nodata. NOT TTL! */
358 int nrrs, rrsz; /* nrrs is 0 if an error occurs */
359 union {
360 void *untyped;
361 unsigned char *bytes;
362 char *(*str); /* ns_raw, cname, ptr, ptr_raw */
363 adns_rr_intstr *(*manyistr); /* txt (list of strings ends with i=-1, str=0) */
364 adns_rr_addr *addr; /* addr */
365 struct in_addr *inaddr; /* a */
366 struct in6_addr *inaddr6; /* aaaa */
367 adns_rr_hostaddr *hostaddr; /* ns */
368 adns_rr_intstrpair *intstrpair; /* hinfo */
369 adns_rr_strpair *strpair; /* rp, rp_raw */
370 adns_rr_inthostaddr *inthostaddr; /* mx */
371 adns_rr_intstr *intstr; /* mx_raw */
372 adns_rr_soa *soa; /* soa, soa_raw */
373 adns_rr_srv *srv; /* srv */
374 adns_rr_srvraw *srvraw; /* srv_raw */
375 } rrs;
376 } adns_answer;
377
378 /* Memory management:
379 * adns_state and adns_query are actually pointers to malloc'd state;
380 * On submission questions are copied, including the owner domain;
381 * Answers are malloc'd as a single piece of memory; pointers in the
382 * answer struct point into further memory in the answer.
383 * query_io:
384 * Must always be non-null pointer;
385 * If *query_io is 0 to start with then any query may be returned;
386 * If *query_io is !0 adns_query then only that query may be returned.
387 * If the call is successful, *query_io, *answer_r, and *context_r
388 * will all be set.
389 * Errors:
390 * Return values are 0 or an errno value.
391 *
392 * For _init, _init_strcfg, _submit and _synchronous, system errors
393 * (eg, failure to create sockets, malloc failure, etc.) return errno
394 * values.
395 *
396 * For _wait and _check failures are reported in the answer
397 * structure, and only 0, ESRCH or (for _check) EAGAIN is
398 * returned: if no (appropriate) requests are done adns_check returns
399 * EAGAIN; if no (appropriate) requests are outstanding both
400 * adns_query and adns_wait return ESRCH.
401 *
402 * Additionally, _wait can return EINTR if you set adns_if_eintr.
403 *
404 * All other errors (nameserver failure, timed out connections, &c)
405 * are returned in the status field of the answer. After a
406 * successful _wait or _check, if status is nonzero then nrrs will be
407 * 0, otherwise it will be >0. type will always be the type
408 * requested.
409 */
410
411 int adns_init(adns_state *newstate_r, adns_initflags flags,
412 FILE *diagfile /*0=>stderr*/);
413
414 int adns_init_strcfg(adns_state *newstate_r, adns_initflags flags,
415 FILE *diagfile /*0=>discard*/, const char *configtext);
416
417 /* Configuration:
418 * adns_init reads /etc/resolv.conf, which is expected to be (broadly
419 * speaking) in the format expected by libresolv, and then
420 * /etc/resolv-adns.conf if it exists. adns_init_strcfg is instead
421 * passed a string which is interpreted as if it were the contents of
422 * resolv.conf or resolv-adns.conf. In general, configuration which
423 * is set later overrides any that is set earlier.
424 *
425 * Standard directives understood in resolv[-adns].conf:
426 *
427 * nameserver <address>
428 * Must be followed by the IP address of a nameserver. Several
429 * nameservers may be specified, and they will be tried in the order
430 * found. There is a compiled in limit, currently 5, on the number
431 * of nameservers. (libresolv supports only 3 nameservers.)
432 *
433 * search <domain> ...
434 * Specifies the search list for queries which specify
435 * adns_qf_search. This is a list of domains to append to the query
436 * domain. The query domain will be tried as-is either before all
437 * of these or after them, depending on the ndots option setting
438 * (see below).
439 *
440 * domain <domain>
441 * This is present only for backward compatibility with obsolete
442 * versions of libresolv. It should not be used, and is interpreted
443 * by adns as if it were `search' - note that this is subtly
444 * different to libresolv's interpretation of this directive.
445 *
446 * sortlist <addr>/<mask> ...
447 * Should be followed by a sequence of IP-address and netmask pairs,
448 * separated by spaces. They may be specified as
449 * eg. 172.30.206.0/24 or 172.30.206.0/255.255.255.0. Currently up
450 * to 15 pairs may be specified (but note that libresolv only
451 * supports up to 10).
452 *
453 * options
454 * Should followed by one or more options, separated by spaces.
455 * Each option consists of an option name, followed by optionally
456 * a colon and a value. Options are listed below.
457 *
458 * Non-standard directives understood in resolv[-adns].conf:
459 *
460 * clearnameservers
461 * Clears the list of nameservers, so that further nameserver lines
462 * start again from the beginning.
463 *
464 * include <filename>
465 * The specified file will be read.
466 *
467 * Additionally, adns will ignore lines in resolv[-adns].conf which
468 * start with a #.
469 *
470 * Standard options understood:
471 *
472 * debug
473 * Enables debugging output from the resolver, which will be written
474 * to stderr.
475 *
476 * ndots:<count>
477 * Affects whether queries with adns_qf_search will be tried first
478 * without adding domains from the searchlist, or whether the bare
479 * query domain will be tried last. Queries which contain at least
480 * <count> dots will be tried bare first. The default is 1.
481 *
482 * Non-standard options understood:
483 *
484 * adns_checkc:none
485 * adns_checkc:entex
486 * adns_checkc:freq
487 * Changes the consistency checking frequency; this overrides the
488 * setting of adns_if_check_entex, adns_if_check_freq, or neither,
489 * in the flags passed to adns_init.
490 *
491 * in6only
492 * in4only
493 * Return only IPv6, respectively only IPv4 addresses, in
494 * _rr_addr's. This may result in an adns_s_nodata error, if the
495 * application only supports, or the remote host only has, the wrong
496 * kind of address.
497 *
498 * There are a number of environment variables which can modify the
499 * behaviour of adns. They take effect only if adns_init is used, and
500 * the caller of adns_init can disable them using adns_if_noenv. In
501 * each case there is both a FOO and an ADNS_FOO; the latter is
502 * interpreted later so that it can override the former. Unless
503 * otherwise stated, environment variables are interpreted after
504 * resolv[-adns].conf are read, in the order they are listed here.
505 *
506 * RES_CONF, ADNS_RES_CONF
507 * A filename, whose contets are in the format of resolv.conf.
508 *
509 * RES_CONF_TEXT, ADNS_RES_CONF_TEXT
510 * A string in the format of resolv.conf.
511 *
512 * RES_OPTIONS, ADNS_RES_OPTIONS
513 * These are parsed as if they appeared in the `options' line of a
514 * resolv.conf. In addition to being parsed at this point in the
515 * sequence, they are also parsed at the very beginning before
516 * resolv.conf or any other environment variables are read, so that
517 * any debug option can affect the processing of the configuration.
518 *
519 * LOCALDOMAIN, ADNS_LOCALDOMAIN
520 * These are interpreted as if their contents appeared in a `search'
521 * line in resolv.conf.
522 */
523
524 int adns_synchronous(adns_state ads,
525 const char *owner,
526 adns_rrtype type,
527 adns_queryflags flags,
528 adns_answer **answer_r);
529
530 /* NB: if you set adns_if_noautosys then _submit and _check do not
531 * make any system calls; you must use some of the asynch-io event
532 * processing functions to actually get things to happen.
533 */
534
535 int adns_submit(adns_state ads,
536 const char *owner,
537 adns_rrtype type,
538 adns_queryflags flags,
539 void *context,
540 adns_query *query_r);
541
542 /* The owner should be quoted in master file format. */
543
544 int adns_check(adns_state ads,
545 adns_query *query_io,
546 adns_answer **answer_r,
547 void **context_r);
548
549 int adns_wait(adns_state ads,
550 adns_query *query_io,
551 adns_answer **answer_r,
552 void **context_r);
553
554 /* same as adns_wait but uses poll(2) internally */
555 int adns_wait_poll(adns_state ads,
556 adns_query *query_io,
557 adns_answer **answer_r,
558 void **context_r);
559
560 void adns_cancel(adns_query query);
561
562 /* The adns_query you get back from _submit is valid (ie, can be
563 * legitimately passed into adns functions) until it is returned by
564 * adns_check or adns_wait, or passed to adns_cancel. After that it
565 * must not be used. You can rely on it not being reused until the
566 * first adns_submit or _transact call using the same adns_state after
567 * it became invalid, so you may compare it for equality with other
568 * query handles until you next call _query or _transact.
569 *
570 * _submit and _synchronous return ENOSYS if they don't understand the
571 * query type.
572 */
573
574 int adns_submit_reverse(adns_state ads,
575 const struct sockaddr *addr,
576 adns_rrtype type,
577 adns_queryflags flags,
578 void *context,
579 adns_query *query_r);
580 /* type must be _r_ptr or _r_ptr_raw. _qf_search is ignored.
581 * addr->sa_family must be AF_INET or AF_INET6 you get ENOSYS.
582 */
583
584 int adns_getaddrinfo(adns_state ads,
585 const char *name, /* Eg, "www.example.coom" */
586 const char *service, /* Eg, "http" */
587 const char *protocol, /* Eg, "tcp" */
588 unsigned short defaultport, /* Eg, 80 */
589 adns_queryflags flags,
590 adns_answer **answer_r, int *invented_r);
591 /* Does an SRV lookup (RFC2052). If this fails, tries an AAAA or A
592 * lookup instead, and if found uses getservbyname to find the port
593 * number (or failing that, uses defaultport). In the `fallback'
594 * case, will invent an SRV record with have priority and weight == 0
595 * and set *invented_r to 1; if real SRV records were found, will set
596 * *invented_r to 0. invented_r may be null but answer_r may not be.
597 * If _getaddrinfo returns nonzero, *answer_r and/or *invented_r may
598 * or may not have been overwritten and should not be used.
599 *
600 * NB, like adns_synchronous, can fail either by returning an errno
601 * value, or by returning an adns_answer with ->nrrs==0 and
602 * ->status!=0.
603 *
604 * You have to write two loops when using the returned value, an outer
605 * one to loop over the returned SRV's, and an inner one to loop over
606 * the addresses for each one.
607 */
608
609 int adns_submit_reverse_any(adns_state ads,
610 const struct sockaddr *addr,
611 const char *rzone,
612 adns_rrtype type,
613 adns_queryflags flags,
614 void *context,
615 adns_query *query_r);
616 /* For RBL-style reverse `zone's; look up
617 * <reversed-address>.<zone>
618 * Any type is allowed. _qf_search is ignored.
619 * addr->sa_family must be AF_INET or you get ENOSYS.
620 */
621
622 void adns_finish(adns_state ads);
623 /* You may call this even if you have queries outstanding;
624 * they will be cancelled.
625 */
626
627
628 void adns_forallqueries_begin(adns_state ads);
629 adns_query adns_forallqueries_next(adns_state ads, void **context_r);
630 /* Iterator functions, which you can use to loop over the outstanding
631 * (submitted but not yet successfuly checked/waited) queries.
632 *
633 * You can only have one iteration going at once. You may call _begin
634 * at any time; after that, an iteration will be in progress. You may
635 * only call _next when an iteration is in progress - anything else
636 * may coredump. The iteration remains in progress until _next
637 * returns 0, indicating that all the queries have been walked over,
638 * or ANY other adns function is called with the same adns_state (or a
639 * query in the same adns_state). There is no need to explicitly
640 * finish an iteration.
641 *
642 * context_r may be 0. *context_r may not be set when _next returns 0.
643 */
644
645 void adns_checkconsistency(adns_state ads, adns_query qu);
646 /* Checks the consistency of adns's internal data structures.
647 * If any error is found, the program will abort().
648 * You may pass 0 for qu; if you pass non-null then additional checks
649 * are done to make sure that qu is a valid query.
650 */
651
652 /*
653 * Example expected/legal calling sequence for submit/check/wait:
654 * adns_init
655 * adns_submit 1
656 * adns_submit 2
657 * adns_submit 3
658 * adns_wait 1
659 * adns_check 3 -> EAGAIN
660 * adns_wait 2
661 * adns_wait 3
662 * ....
663 * adns_finish
664 */
665
666 /*
667 * Entrypoints for generic asynch io:
668 * (these entrypoints are not very useful except in combination with *
669 * some of the other I/O model calls which can tell you which fds to
670 * be interested in):
671 *
672 * Note that any adns call may cause adns to open and close fds, so
673 * you must call beforeselect or beforepoll again just before
674 * blocking, or you may not have an up-to-date list of it's fds.
675 */
676
677 int adns_processany(adns_state ads);
678 /* Gives adns flow-of-control for a bit. This will never block, and
679 * can be used with any threading/asynch-io model. If some error
680 * occurred which might cause an event loop to spin then the errno
681 * value is returned.
682 */
683
684 int adns_processreadable(adns_state ads, int fd, const struct timeval *now);
685 int adns_processwriteable(adns_state ads, int fd, const struct timeval *now);
686 int adns_processexceptional(adns_state ads, int fd, const struct timeval *now);
687 /* Gives adns flow-of-control so that it can process incoming data
688 * from, or send outgoing data via, fd. Very like _processany. If it
689 * returns zero then fd will no longer be readable or writeable
690 * (unless of course more data has arrived since). adns will _only_
691 * use that fd and only in the manner specified, regardless of whether
692 * adns_if_noautosys was specified.
693 *
694 * adns_processexceptional should be called when select(2) reports an
695 * exceptional condition, or poll(2) reports POLLPRI.
696 *
697 * It is fine to call _processreabable or _processwriteable when the
698 * fd is not ready, or with an fd that doesn't belong to adns; it will
699 * then just return 0.
700 *
701 * If some error occurred which might prevent an event loop to spin
702 * then the errno value is returned.
703 */
704
705 void adns_processtimeouts(adns_state ads, const struct timeval *now);
706 /* Gives adns flow-of-control so that it can process any timeouts
707 * which might have happened. Very like _processreadable/writeable.
708 *
709 * now may be 0; if it isn't, *now must be the current time, recently
710 * obtained from gettimeofday.
711 */
712
713 void adns_firsttimeout(adns_state ads,
714 struct timeval **tv_mod, struct timeval *tv_buf,
715 struct timeval now);
716 /* Asks adns when it would first like the opportunity to time
717 * something out. now must be the current time, from gettimeofday.
718 *
719 * If tv_mod points to 0 then tv_buf must be non-null, and
720 * _firsttimeout will fill in *tv_buf with the time until the first
721 * timeout, and make *tv_mod point to tv_buf. If adns doesn't have
722 * anything that might need timing out it will leave *tv_mod as 0.
723 *
724 * If *tv_mod is not 0 then tv_buf is not used. adns will update
725 * *tv_mod if it has any earlier timeout, and leave it alone if it
726 * doesn't.
727 *
728 * This call will not actually do any I/O, or change the fds that adns
729 * is using. It always succeeds and never blocks.
730 */
731
732 void adns_globalsystemfailure(adns_state ads);
733 /* If serious problem(s) happen which globally affect your ability to
734 * interact properly with adns, or adns's ability to function
735 * properly, you or adns can call this function.
736 *
737 * All currently outstanding queries will be made to fail with
738 * adns_s_systemfail, and adns will close any stream sockets it has
739 * open.
740 *
741 * This is used by adns, for example, if gettimeofday() fails.
742 * Without this the program's event loop might start to spin !
743 *
744 * This call will never block.
745 */
746
747 /*
748 * Entrypoints for select-loop based asynch io:
749 */
750
751 void adns_beforeselect(adns_state ads, int *maxfd, fd_set *readfds,
752 fd_set *writefds, fd_set *exceptfds,
753 struct timeval **tv_mod, struct timeval *tv_buf,
754 const struct timeval *now);
755 /* Find out file descriptors adns is interested in, and when it would
756 * like the opportunity to time something out. If you do not plan to
757 * block then tv_mod may be 0. Otherwise, tv_mod and tv_buf are as
758 * for adns_firsttimeout. readfds, writefds, exceptfds and maxfd_io may
759 * not be 0.
760 *
761 * If now is not 0 then this will never actually do any I/O, or
762 * change the fds that adns is using or the timeouts it wants. In any
763 * case it won't block.
764 */
765
766 void adns_afterselect(adns_state ads, int maxfd, const fd_set *readfds,
767 const fd_set *writefds, const fd_set *exceptfds,
768 const struct timeval *now);
769 /* Gives adns flow-of-control for a bit; intended for use after
770 * select. This is just a fancy way of calling adns_processreadable/
771 * writeable/timeouts as appropriate, as if select had returned the
772 * data being passed. Always succeeds.
773 */
774
775 /*
776 * Example calling sequence:
777 *
778 * adns_init _noautosys
779 * loop {
780 * adns_beforeselect
781 * select
782 * adns_afterselect
783 * ...
784 * adns_submit / adns_check
785 * ...
786 * }
787 */
788
789 /*
790 * Entrypoints for poll-loop based asynch io:
791 */
792
793 struct pollfd;
794 /* In case your system doesn't have it or you forgot to include
795 * <sys/poll.h>, to stop the following declarations from causing
796 * problems. If your system doesn't have poll then the following
797 * entrypoints will not be defined in libadns. Sorry !
798 */
799
800 int adns_beforepoll(adns_state ads, struct pollfd *fds, int *nfds_io, int *timeout_io,
801 const struct timeval *now);
802 /* Finds out which fd's adns is interested in, and when it would like
803 * to be able to time things out. This is in a form suitable for use
804 * with poll(2).
805 *
806 * On entry, usually fds should point to at least *nfds_io structs.
807 * adns will fill up to that many structs will information for poll,
808 * and record in *nfds_io how many structs it filled. If it wants to
809 * listen for more structs then *nfds_io will be set to the number
810 * required and _beforepoll will return ERANGE.
811 *
812 * You may call _beforepoll with fds==0 and *nfds_io 0, in which case
813 * adns will fill in the number of fds that it might be interested in
814 * in *nfds_io, and always return either 0 (if it is not interested in
815 * any fds) or ERANGE (if it is).
816 *
817 * NOTE that (unless now is 0) adns may acquire additional fds
818 * from one call to the next, so you must put adns_beforepoll in a
819 * loop, rather than assuming that the second call (with the buffer
820 * size requested by the first) will not return ERANGE.
821 *
822 * adns only ever sets POLLIN, POLLOUT and POLLPRI in its pollfd
823 * structs, and only ever looks at those bits. POLLPRI is required to
824 * detect TCP Urgent Data (which should not be used by a DNS server)
825 * so that adns can know that the TCP stream is now useless.
826 *
827 * In any case, *timeout_io should be a timeout value as for poll(2),
828 * which adns will modify downwards as required. If the caller does
829 * not plan to block then *timeout_io should be 0 on entry, or
830 * alternatively, timeout_io may be 0. (Alternatively, the caller may
831 * use _beforeselect with timeout_io==0 to find out about file
832 * descriptors, and use _firsttimeout is used to find out when adns
833 * might want to time something out.)
834 *
835 * adns_beforepoll will return 0 on success, and will not fail for any
836 * reason other than the fds buffer being too small (ERANGE).
837 *
838 * This call will never actually do any I/O. If you supply the
839 * current time it will not change the fds that adns is using or the
840 * timeouts it wants.
841 *
842 * In any case this call won't block.
843 */
844
845 #define ADNS_POLLFDS_RECOMMENDED 2
846 /* If you allocate an fds buf with at least RECOMMENDED entries then
847 * you are unlikely to need to enlarge it. You are recommended to do
848 * so if it's convenient. However, you must be prepared for adns to
849 * require more space than this.
850 */
851
852 void adns_afterpoll(adns_state ads, const struct pollfd *fds, int nfds,
853 const struct timeval *now);
854 /* Gives adns flow-of-control for a bit; intended for use after
855 * poll(2). fds and nfds should be the results from poll(). pollfd
856 * structs mentioning fds not belonging to adns will be ignored.
857 */
858
859
860 adns_status adns_rr_info(adns_rrtype type,
861 const char **rrtname_r, const char **fmtname_r,
862 int *len_r,
863 const void *datap, char **data_r);
864 /*
865 * Get information about a query type, or convert reply data to a
866 * textual form. type must be specified, and the official name of the
867 * corresponding RR type will be returned in *rrtname_r, and
868 * information about the processing style in *fmtname_r. The length
869 * of the table entry in an answer for that type will be returned in
870 * in *len_r. Any or all of rrtname_r, fmtname_r and len_r may be 0.
871 * If fmtname_r is non-null then *fmtname_r may be null on return,
872 * indicating that no special processing is involved.
873 *
874 * data_r be must be non-null iff datap is. In this case *data_r will
875 * be set to point to a string pointing to a representation of the RR
876 * data in master file format. (The owner name, timeout, class and
877 * type will not be present - only the data part of the RR.) The
878 * memory will have been obtained from malloc() and must be freed by
879 * the caller.
880 *
881 * Usually this routine will succeed. Possible errors include:
882 * adns_s_nomemory
883 * adns_s_rrtypeunknown
884 * adns_s_invaliddata (*datap contained garbage)
885 * If an error occurs then no memory has been allocated,
886 * and *rrtname_r, *fmtname_r, *len_r and *data_r are undefined.
887 *
888 * There are some adns-invented data formats which are not official
889 * master file formats. These include:
890 *
891 * Mailboxes if __qtf_mail822: these are just included as-is.
892 *
893 * Addresses (adns_rr_addr): these may be of pretty much any type.
894 * The representation is in two parts: first, a word for the address
895 * family (ie, in AF_XXX, the XXX), and then one or more items for the
896 * address itself, depending on the format. For an IPv4 address the
897 * syntax is INET followed by the dotted quad (from inet_ntoa).
898 * Currently only IPv4 is supported.
899 *
900 * Text strings (as in adns_rr_txt) appear inside double quotes, and
901 * use \" and \\ to represent " and \, and \xHH to represent
902 * characters not in the range 32-126.
903 *
904 * Hostname with addresses (adns_rr_hostaddr): this consists of the
905 * hostname, as usual, followed by the adns_status value, as an
906 * abbreviation, and then a descriptive string (encoded as if it were
907 * a piece of text), for the address lookup, followed by zero or more
908 * addresses enclosed in ( and ). If the result was a temporary
909 * failure, then a single ? appears instead of the ( ). If the
910 * result was a permanent failure then an empty pair of parentheses
911 * appears (which a space in between). For example, one of the NS
912 * records for greenend.org.uk comes out like
913 * ns.chiark.greenend.org.uk ok "OK" ( INET 195.224.76.132 )
914 * an MX referring to a nonexistent host might come out like:
915 * 50 sun2.nsfnet-relay.ac.uk nxdomain "No such domain" ( )
916 * and if nameserver information is not available you might get:
917 * dns2.spong.dyn.ml.org timeout "DNS query timed out" ?
918 */
919
920 const char *adns_strerror(adns_status st);
921 const char *adns_errabbrev(adns_status st);
922 const char *adns_errtypeabbrev(adns_status st);
923 /* Like strerror but for adns_status values. adns_errabbrev returns
924 * the abbreviation of the error - eg, for adns_s_timeout it returns
925 * "timeout". adns_errtypeabbrev returns the abbreviation of the
926 * error class: ie, for values up to adns_s_max_XXX it will return the
927 * string XXX. You MUST NOT call these functions with status values
928 * not returned by the same adns library.
929 */
930
931 #ifdef __cplusplus
932 } /* end of extern "C" */
933 #endif
934 #endif