3 * - adns user-visible API
8 * Copyright (C) 1997-2000,2003,2006,2014 Ian Jackson
10 * It is part of adns, which is
11 * Copyright (C) 1997-2000,2003,2006,2014 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 3, 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.
57 #ifndef ADNS_H_INCLUDED
58 #define ADNS_H_INCLUDED
63 #include <sys/types.h>
64 #include <sys/socket.h>
65 #include <netinet/in.h>
71 extern "C" { /* I really dislike this - iwj. */
74 /* Whether to support address families other than IPv4 in responses which use
75 * the `adns_rr_addr' structure. This is a source-compatibility issue: old
76 * clients may not expect to find address families other than AF_INET in
77 * their query results. There's a separate binary compatibility issue to do
78 * with the size of the `adns_rr_addr' structure, but we'll assume you can
79 * cope with that because you have this header file. Define
80 * `ADNS_FEATURE_IPV4ONLY' if you only want to see AF_INET addresses by
81 * default, or `ADNS_FEATURE_MANYAF' to allow multiple address families; the
82 * default is currently to stick with AF_INET only, but this is likely to
83 * change in a later release of ADNS. Note that any adns_qf_want_... flags
84 * in your query are observed: this setting affects only the default address
87 #if !defined(ADNS_FEATURE_IPV4ONLY) && !defined(ADNS_FEATURE_MANYAF)
88 # define ADNS_FEATURE_IPV4ONLY
89 #elif defined(ADNS_FEATURE_IPV4ONLY) && defined(ADNS_FEATURE_MANYAF)
90 # error "Feature flags ADNS_FEATURE_IPV4ONLY and ..._MANYAF are incompatible"
93 /* All struct in_addr anywhere in adns are in NETWORK byte order. */
95 typedef struct adns__state *adns_state;
96 typedef struct adns__query *adns_query;
98 typedef enum { /* In general, or together the desired flags: */
99 adns_if_none= 0x0000,/* no flags. nicer than 0 for some compilers */
100 adns_if_noenv= 0x0001,/* do not look at environment */
101 adns_if_noerrprint= 0x0002,/* never print to stderr (_debug overrides) */
102 adns_if_noserverwarn=0x0004,/* do not warn to stderr about duff servers etc */
103 adns_if_debug= 0x0008,/* enable all output to stderr plus debug msgs */
104 adns_if_logpid= 0x0080,/* include pid in diagnostic output */
105 adns_if_noautosys= 0x0010,/* do not make syscalls at every opportunity */
106 adns_if_eintr= 0x0020,/* allow _wait and _synchronous to return EINTR */
107 adns_if_nosigpipe= 0x0040,/* applic has SIGPIPE ignored, do not protect */
108 adns_if_checkc_entex=0x0100,/* consistency checks on entry/exit to adns fns */
109 adns_if_checkc_freq= 0x0300,/* consistency checks very frequently (slow!) */
111 adns_if_permit_ipv4= 0x0400,/* allow _addr queries to return IPv4 addresses */
112 adns_if_permit_ipv6= 0x0800,/* allow _addr queries to return IPv6 addresses */
113 adns_if_afmask= 0x0c00,
114 /* These are policy flags, and overridden by the adns_af:... option in
115 * resolv.conf. If the adns_qf_want_... query flags are incompatible with
116 * these settings (in the sense that no address families are permitted at
117 * all) then the query flags take precedence; otherwise only records which
118 * satisfy all of the stated requirements are allowed.
120 adns__if_sizeforce= 0x7fff,
123 typedef enum { /* In general, or together the desired flags: */
124 adns_qf_none= 0x00000000,/* no flags */
125 adns_qf_search= 0x00000001,/* use the searchlist */
126 adns_qf_usevc= 0x00000002,/* use a virtual circuit (TCP conn) */
127 adns_qf_owner= 0x00000004,/* fill in the owner field in the answer */
128 adns_qf_quoteok_query= 0x00000010,/* allow special chars in query domain */
129 adns_qf_quoteok_cname= 0x00000000,/* ... in CNAME we go via (now default) */
130 adns_qf_quoteok_anshost=0x00000040,/* ... in things supposedly hostnames */
131 adns_qf_quotefail_cname=0x00000080,/* refuse if quote-req chars in CNAME we go via */
132 adns_qf_cname_loose= 0x00000100,/* allow refs to CNAMEs - without, get _s_cname */
133 adns_qf_cname_strict= 0x00010000,/* forbid CNAME refs (default, currently) */
134 adns_qf_cname_forbid= 0x00000200,/* don't follow CNAMEs, instead give _s_cname */
136 adns_qf_want_ipv4= 0x00000400,/* try to return IPv4 addresses */
137 adns_qf_want_ipv6= 0x00000800,/* try to return IPv6 addresses */
138 adns_qf_want_allaf= 0x00000c00,/* all the above flag bits */
139 /* Without any of the _qf_want_... flags, _qtf_deref queries try to return
140 * all address families permitted by _if_permit_... (as overridden by the
141 * `adns_af:...' configuration option). Set flags to restrict the
142 * returned address families to the ones selected.
144 adns_qf_ipv6_mapv4= 0x00001000,/* ... return IPv4 addresses as v6-mapped */
146 adns_qf_addrlit_scope_forbid=0x00002000,/* forbid %<scope> in IPv6 literals */
147 adns_qf_addrlit_scope_numeric=0x00004000,/* %<scope> may only be numeric */
148 adns_qf_addrlit_ipv4_quadonly=0x00008000,/* reject non-dotted-quad ipv4 */
150 adns__qf_internalmask= 0x0ff00000,
151 adns__qf_sizeforce= 0x7fffffff
155 adns_rrt_typemask= 0x0ffff,
156 adns_rrt_reprmask= 0xffffff,
157 adns__qtf_deref_bit=0x10000,/* internal version of ..._deref below */
158 adns__qtf_mail822= 0x20000,/* return mailboxes in RFC822 rcpt field fmt */
160 adns__qtf_bigaddr=0x1000000,/* use the new larger sockaddr union */
161 adns__qtf_manyaf= 0x2000000,/* permitted to return multiple address families */
163 adns__qtf_deref= adns__qtf_deref_bit|adns__qtf_bigaddr
164 #ifdef ADNS_FEATURE_MANYAF
167 ,/* dereference domains; perhaps get extra data */
169 adns_r_unknown= 0x40000,
170 /* To use this, ask for records of type <rr-type-code>|adns_r_unknown.
171 * adns will not process the RDATA - you'll get adns_rr_byteblocks,
172 * where the int is the length and the unsigned char* points to the
173 * data. String representation of the RR data (by adns_rrinfo) is as in
174 * RFC3597. adns_rr_info will not return the type name in *rrtname_r
175 * (due to memory management problems); *fmtname_r will be set to
178 * Do not specify adns_r_unknown along with a known RR type which
179 * requires domain name uncompression (see RFC3597 s4); domain names
180 * will not be uncompressed and the resulting data would be useless.
181 * Asking for meta-RR types via adns_r_unknown will not work properly
182 * either and may make adns complain about server misbehaviour, so don't
185 * Don't forget adns_qf_quoteok if that's what you want. */
192 adns_r_ns= adns_r_ns_raw|adns__qtf_deref,
197 adns_r_soa= adns_r_soa_raw|adns__qtf_mail822,
199 adns_r_ptr_raw= 12, /* do not mind PTR with wrong or missing addr */
200 adns_r_ptr= adns_r_ptr_raw|adns__qtf_deref,
205 adns_r_mx= adns_r_mx_raw|adns__qtf_deref,
210 adns_r_rp= adns_r_rp_raw|adns__qtf_mail822,
214 /* For SRV records, query domain without _qf_quoteok_query must look
215 * as expected from SRV RFC with hostname-like Name. _With_
216 * _quoteok_query, any query domain is allowed. */
218 adns_r_srv= adns_r_srv_raw|adns__qtf_deref,
220 adns_r_addr= adns_r_a|adns__qtf_deref,
222 adns__rrt_sizeforce= 0x7fffffff,
227 * In queries without qf_quoteok_*, all domains must have standard
228 * legal syntax, or you get adns_s_querydomainvalid (if the query
229 * domain contains bad characters) or adns_s_answerdomaininvalid (if
230 * the answer contains bad characters).
232 * In queries _with_ qf_quoteok_*, domains in the query or response
233 * may contain any characters, quoted according to RFC1035 5.1. On
234 * input to adns, the char* is a pointer to the interior of a "
235 * delimited string, except that " may appear in it unquoted. On
236 * output, the char* is a pointer to a string which would be legal
237 * either inside or outside " delimiters; any character which isn't
238 * legal in a hostname (ie alphanumeric or hyphen) or one of _ / +
239 * (the three other punctuation characters commonly abused in domain
240 * names) will be quoted, as \X if it is a printing ASCII character or
243 * If the query goes via a CNAME then the canonical name (ie, the
244 * thing that the CNAME record refers to) is usually allowed to
245 * contain any characters, which will be quoted as above. With
246 * adns_qf_quotefail_cname you get adns_s_answerdomaininvalid when
247 * this happens. (This is a change from version 0.4 and earlier, in
248 * which failing the query was the default, and you had to say
249 * adns_qf_quoteok_cname to avoid this; that flag is now deprecated.)
251 * In version 0.4 and earlier, asking for _raw records containing
252 * mailboxes without specifying _qf_quoteok_anshost was silly. This
253 * is no longer the case. In this version only parts of responses
254 * that are actually supposed to be hostnames will be refused by
255 * default if quote-requiring characters are found.
259 * If you ask for an RR which contains domains which are actually
260 * encoded mailboxes, and don't ask for the _raw version, then adns
261 * returns the mailbox formatted suitably for an RFC822 recipient
262 * header field. The particular format used is that if the mailbox
263 * requires quoting according to the rules in RFC822 then the
264 * local-part is quoted in double quotes, which end at the next
265 * unescaped double quote (\ is the escape char, and is doubled, and
266 * is used to escape only \ and "). If the local-part is legal
267 * without quoting according to RFC822, it is presented as-is. In any
268 * case the local-part is followed by an @ and the domain. The domain
269 * will not contain any characters not legal in hostnames.
271 * Unquoted local-parts may contain any printing 7-bit ASCII
272 * except the punctuation characters ( ) < > @ , ; : \ " [ ]
273 * I.e. they may contain alphanumerics, and the following
274 * punctuation characters: ! # % ^ & * - _ = + { } .
276 * adns will reject local parts containing control characters (byte
277 * values 0-31, 127-159, and 255) - these appear to be legal according
278 * to RFC822 (at least 0-127) but are clearly a bad idea. RFC1035
279 * syntax does not make any distinction between a single RFC822
280 * quoted-string containing full stops, and a series of quoted-strings
281 * separated by full stops; adns will return anything that isn't all
282 * valid atoms as a single quoted-string. RFC822 does not allow
283 * high-bit-set characters at all, but adns does allow them in
284 * local-parts, treating them as needing quoting.
286 * If you ask for the domain with _raw then _no_ checking is done
287 * (even on the host part, regardless of adns_qf_quoteok_anshost), and
288 * you just get the domain name in master file format.
290 * If no mailbox is supplied the returned string will be `.' in either
297 /* locally induced errors */
299 adns_s_unknownrrtype,
302 adns_s_max_localfail= 29,
304 /* remotely induced errors, detected locally */
308 adns_s_invalidresponse,
309 adns_s_unknownformat,
311 adns_s_max_remotefail= 59,
313 /* remotely induced errors, reported by remote server to us */
314 adns_s_rcodeservfail,
315 adns_s_rcodeformaterror,
316 adns_s_rcodenotimplemented,
320 adns_s_max_tempfail= 99,
322 /* remote configuration errors */
323 adns_s_inconsistent, /* PTR gives domain whose addr is missing or mismatch */
324 adns_s_prohibitedcname, /* CNAME, but eg A expected (not if _qf_cname_loose) */
325 adns_s_answerdomaininvalid,
326 adns_s_answerdomaintoolong,
329 adns_s_max_misconfig= 199,
331 /* permanent problems with the query */
332 adns_s_querydomainwrong,
333 adns_s_querydomaininvalid,
334 adns_s_querydomaintoolong,
336 adns_s_max_misquery= 299,
338 /* permanent errors */
342 adns_s_max_permfail= 499
348 struct sockaddr_in inet;
349 } adns_sockaddr_v4only;
353 struct sockaddr_in inet;
354 struct sockaddr_in6 inet6;
363 /* the old v4-only structure; handy if you have complicated binary
364 * compatibility problems. */
366 adns_sockaddr_v4only addr;
367 } adns_rr_addr_v4only;
372 int naddrs; /* temp fail => -1, perm fail => 0, s_ok => >0 */
383 } adns_rr_inthostaddr;
386 /* Used both for mx_raw, in which case i is the preference and str
387 * the domain, and for txt, in which case each entry has i for the
388 * `text' length, and str for the data (which will have had an extra
389 * nul appended so that if it was plain text it is now a
390 * null-terminated string).
397 adns_rr_intstr array[2];
398 } adns_rr_intstrpair;
402 unsigned long serial, refresh, retry, expire, minimum;
406 int priority, weight, port;
411 int priority, weight, port;
422 char *cname; /* always NULL if query was for CNAME records */
423 char *owner; /* only set if req'd in query flags; maybe 0 on error anyway */
424 adns_rrtype type; /* guaranteed to be same as in query */
425 time_t expires;/*abs time. def only if _s_ok, nxdomain or nodata. NOT TTL!*/
426 int nrrs, rrsz; /* nrrs is 0 if an error occurs */
429 unsigned char *bytes;
430 char *(*str); /* ns_raw, cname, ptr, ptr_raw */
431 adns_rr_intstr *(*manyistr); /* txt (list strs ends with i=-1, str=0)*/
432 adns_rr_addr *addr; /* addr */
433 struct in_addr *inaddr; /* a */
434 struct in6_addr *in6addr; /* aaaa */
435 adns_rr_hostaddr *hostaddr; /* ns */
436 adns_rr_intstrpair *intstrpair; /* hinfo */
437 adns_rr_strpair *strpair; /* rp, rp_raw */
438 adns_rr_inthostaddr *inthostaddr;/* mx */
439 adns_rr_intstr *intstr; /* mx_raw */
440 adns_rr_soa *soa; /* soa, soa_raw */
441 adns_rr_srvraw *srvraw; /* srv_raw */
442 adns_rr_srvha *srvha;/* srv */
443 adns_rr_byteblock *byteblock; /* ...|unknown */
447 /* Memory management:
448 * adns_state and adns_query are actually pointers to malloc'd state;
449 * On submission questions are copied, including the owner domain;
450 * Answers are malloc'd as a single piece of memory; pointers in the
451 * answer struct point into further memory in the answer.
453 * Must always be non-null pointer;
454 * If *query_io is 0 to start with then any query may be returned;
455 * If *query_io is !0 adns_query then only that query may be returned.
456 * If the call is successful, *query_io, *answer_r, and *context_r
459 * Return values are 0 or an errno value.
461 * For _init, _init_strcfg, _submit and _synchronous, system errors
462 * (eg, failure to create sockets, malloc failure, etc.) return errno
463 * values. EINVAL from _init et al means the configuration file
464 * is erroneous and cannot be parsed.
466 * For _wait and _check failures are reported in the answer
467 * structure, and only 0, ESRCH or (for _check) EAGAIN is
468 * returned: if no (appropriate) requests are done adns_check returns
469 * EAGAIN; if no (appropriate) requests are outstanding both
470 * adns_query and adns_wait return ESRCH.
472 * Additionally, _wait can return EINTR if you set adns_if_eintr.
474 * All other errors (nameserver failure, timed out connections, &c)
475 * are returned in the status field of the answer. After a
476 * successful _wait or _check, if status is nonzero then nrrs will be
477 * 0, otherwise it will be >0. type will always be the type
482 * adns does not use any static modifiable state, so it
483 * is safe to call adns_init several times and then use the
484 * resulting adns_states concurrently.
485 * However, it is NOT safe to make simultaneous calls into
486 * adns using the same adns_state; a single adns_state must be used
487 * only by one thread at a time. You can solve this problem by
488 * having one adns_state per thread, or if that isn't feasible, you
489 * could maintain a pool of adns_states. Unfortunately neither of
490 * these approaches has optimal performance.
493 int adns_init(adns_state *newstate_r, adns_initflags flags,
494 FILE *diagfile /*0=>stderr*/);
496 int adns_init_strcfg(adns_state *newstate_r, adns_initflags flags,
497 FILE *diagfile /*0=>discard*/, const char *configtext);
499 typedef void adns_logcallbackfn(adns_state ads, void *logfndata,
500 const char *fmt, va_list al);
501 /* Will be called perhaps several times for each message; when the
502 * message is complete, the string implied by fmt and al will end in
503 * a newline. Log messages start with `adns debug:' or `adns
504 * warning:' or `adns:' (for errors), or `adns debug [PID]:'
505 * etc. if adns_if_logpid is set. */
507 int adns_init_logfn(adns_state *newstate_r, adns_initflags flags,
508 const char *configtext /*0=>use default config files*/,
509 adns_logcallbackfn *logfn /*0=>logfndata is a FILE* */,
510 void *logfndata /*0 with logfn==0 => discard*/);
513 * adns_init reads /etc/resolv.conf, which is expected to be (broadly
514 * speaking) in the format expected by libresolv, and then
515 * /etc/resolv-adns.conf if it exists. adns_init_strcfg is instead
516 * passed a string which is interpreted as if it were the contents of
517 * resolv.conf or resolv-adns.conf. In general, configuration which
518 * is set later overrides any that is set earlier.
520 * Standard directives understood in resolv[-adns].conf:
522 * nameserver <address>
523 * Must be followed by the IP address of a nameserver. Several
524 * nameservers may be specified, and they will be tried in the order
525 * found. There is a compiled in limit, currently 5, on the number
526 * of nameservers. (libresolv supports only 3 nameservers.)
528 * search <domain> ...
529 * Specifies the search list for queries which specify
530 * adns_qf_search. This is a list of domains to append to the query
531 * domain. The query domain will be tried as-is either before all
532 * of these or after them, depending on the ndots option setting
536 * This is present only for backward compatibility with obsolete
537 * versions of libresolv. It should not be used, and is interpreted
538 * by adns as if it were `search' - note that this is subtly
539 * different to libresolv's interpretation of this directive.
541 * sortlist <addr>/<mask> ...
542 * Should be followed by a sequence of IP-address and netmask pairs,
543 * separated by spaces. They may be specified as
544 * eg. 172.30.206.0/24 or 172.30.206.0/255.255.255.0. Currently up
545 * to 15 pairs may be specified (but note that libresolv only
546 * supports up to 10).
549 * Should followed by one or more options, separated by spaces.
550 * Each option consists of an option name, followed by optionally
551 * a colon and a value. Options are listed below.
553 * Non-standard directives understood in resolv[-adns].conf:
556 * Clears the list of nameservers, so that further nameserver lines
557 * start again from the beginning.
560 * The specified file will be read.
562 * Additionally, adns will ignore lines in resolv[-adns].conf which
565 * Standard options understood:
568 * Enables debugging output from the resolver, which will be written
572 * Affects whether queries with adns_qf_search will be tried first
573 * without adding domains from the searchlist, or whether the bare
574 * query domain will be tried last. Queries which contain at least
575 * <count> dots will be tried bare first. The default is 1.
577 * Non-standard options understood:
582 * Changes the consistency checking frequency; this overrides the
583 * setting of adns_if_check_entex, adns_if_check_freq, or neither,
584 * in the flags passed to adns_init.
586 * adns_af:{ipv4,ipv6},... adns_af:any
587 * Determines which address families ADNS looks up (either as an
588 * adns_r_addr query, or when dereferencing an answer yielding hostnames
589 * (e.g., adns_r_mx). The argument is a comma-separated list: only the
590 * address families listed will be looked up. The default is `any'.
591 * Lookups occur (logically) concurrently; use the `sortlist' directive to
592 * control the relative order of addresses in answers. This option
593 * overrides the corresponding init flags (covered by adns_if_afmask).
595 * There are a number of environment variables which can modify the
596 * behaviour of adns. They take effect only if adns_init is used, and
597 * the caller of adns_init can disable them using adns_if_noenv. In
598 * each case there is both a FOO and an ADNS_FOO; the latter is
599 * interpreted later so that it can override the former. Unless
600 * otherwise stated, environment variables are interpreted after
601 * resolv[-adns].conf are read, in the order they are listed here.
603 * RES_CONF, ADNS_RES_CONF
604 * A filename, whose contets are in the format of resolv.conf.
606 * RES_CONF_TEXT, ADNS_RES_CONF_TEXT
607 * A string in the format of resolv.conf.
609 * RES_OPTIONS, ADNS_RES_OPTIONS
610 * These are parsed as if they appeared in the `options' line of a
611 * resolv.conf. In addition to being parsed at this point in the
612 * sequence, they are also parsed at the very beginning before
613 * resolv.conf or any other environment variables are read, so that
614 * any debug option can affect the processing of the configuration.
616 * LOCALDOMAIN, ADNS_LOCALDOMAIN
617 * These are interpreted as if their contents appeared in a `search'
618 * line in resolv.conf.
621 int adns_synchronous(adns_state ads,
624 adns_queryflags flags,
625 adns_answer **answer_r);
627 /* NB: if you set adns_if_noautosys then _submit and _check do not
628 * make any system calls; you must use some of the asynch-io event
629 * processing functions to actually get things to happen.
632 int adns_submit(adns_state ads,
635 adns_queryflags flags,
637 adns_query *query_r);
639 /* The owner should be quoted in master file format. */
641 int adns_check(adns_state ads,
642 adns_query *query_io,
643 adns_answer **answer_r,
646 int adns_wait(adns_state ads,
647 adns_query *query_io,
648 adns_answer **answer_r,
651 /* same as adns_wait but uses poll(2) internally */
652 int adns_wait_poll(adns_state ads,
653 adns_query *query_io,
654 adns_answer **answer_r,
657 void adns_cancel(adns_query query);
659 /* The adns_query you get back from _submit is valid (ie, can be
660 * legitimately passed into adns functions) until it is returned by
661 * adns_check or adns_wait, or passed to adns_cancel. After that it
662 * must not be used. You can rely on it not being reused until the
663 * first adns_submit or _transact call using the same adns_state after
664 * it became invalid, so you may compare it for equality with other
665 * query handles until you next call _query or _transact.
667 * _submit and _synchronous return ENOSYS if they don't understand the
671 int adns_submit_reverse(adns_state ads,
672 const struct sockaddr *addr,
674 adns_queryflags flags,
676 adns_query *query_r);
677 /* type must be _r_ptr or _r_ptr_raw. _qf_search is ignored.
678 * addr->sa_family must be AF_INET or you get ENOSYS.
681 int adns_submit_reverse_any(adns_state ads,
682 const struct sockaddr *addr,
685 adns_queryflags flags,
687 adns_query *query_r);
688 /* For RBL-style reverse `zone's; look up
689 * <reversed-address>.<zone>
690 * Any type is allowed. _qf_search is ignored.
691 * addr->sa_family must be AF_INET or you get ENOSYS.
694 void adns_finish(adns_state ads);
695 /* You may call this even if you have queries outstanding;
696 * they will be cancelled.
699 #define ADNS_ADDR2TEXT_BUFLEN \
700 (INET6_ADDRSTRLEN + 1/*%*/ \
701 + ((IF_NAMESIZE-1) > 9 ? (IF_NAMESIZE-1) : 9/*uint32*/) \
702 + 1/* nul; included in IF_NAMESIZE */)
704 int adns_text2addr(const char *text, uint16_t port, adns_queryflags flags,
705 struct sockaddr *sa_r,
706 socklen_t *salen_io /* updated iff OK or ENOSPC */);
707 int adns_addr2text(const struct sockaddr *sa, adns_queryflags flags,
708 char *buffer, int *buflen_io /* updated ONLY on ENOSPC */,
709 int *port_r /* may be 0 */);
711 * port is always in host byte order and is simply copied to and
712 * from the appropriate sockaddr field (byteswapped as necessary).
714 * The only flags supported are adns_qf_addrlit_...; others are
717 * Error return values are:
719 * ENOSPC Output buffer is too small. Can only happen if
720 * *buflen_io < ADNS_ADDR2TEXT_BUFLEN or
721 * *salen_io < sizeof(adns_sockaddr). On return,
722 * *buflen_io or *salen_io has been updated by adns.
724 * EINVAL text has invalid syntax.
726 * text represents an address family not supported by
727 * this version of adns.
729 * Scoped address supplied (text contained "%" or
730 * sin6_scope_id nonzero) but caller specified
731 * adns_qf_addrlit_scope_forbid.
733 * Scope name (rather than number) supplied in text but
734 * caller specified adns_qf_addrlit_scope_numeric.
736 * EAFNOSUPPORT sa->sa_family is not supported (addr2text only).
738 * Only if neither adns_qf_addrlit_scope_forbid nor
739 * adns_qf_addrlit_scope_numeric are set:
741 * ENOSYS Scope name supplied in text but IPv6 address part of
742 * sockaddr is not a link local address.
744 * ENXIO Scope name supplied in text but if_nametoindex
745 * said it wasn't a valid local interface name.
747 * EIO Scoped address supplied but if_nametoindex failed
748 * in an unexpected way; adns has printed a message to
751 * any other if_nametoindex failed in a more-or-less expected way.
754 void adns_forallqueries_begin(adns_state ads);
755 adns_query adns_forallqueries_next(adns_state ads, void **context_r);
756 /* Iterator functions, which you can use to loop over the outstanding
757 * (submitted but not yet successfuly checked/waited) queries.
759 * You can only have one iteration going at once. You may call _begin
760 * at any time; after that, an iteration will be in progress. You may
761 * only call _next when an iteration is in progress - anything else
762 * may coredump. The iteration remains in progress until _next
763 * returns 0, indicating that all the queries have been walked over,
764 * or ANY other adns function is called with the same adns_state (or a
765 * query in the same adns_state). There is no need to explicitly
766 * finish an iteration.
768 * context_r may be 0. *context_r may not be set when _next returns 0.
771 void adns_checkconsistency(adns_state ads, adns_query qu);
772 /* Checks the consistency of adns's internal data structures.
773 * If any error is found, the program will abort().
774 * You may pass 0 for qu; if you pass non-null then additional checks
775 * are done to make sure that qu is a valid query.
779 * Example expected/legal calling sequence for submit/check/wait:
785 * adns_check 3 -> EAGAIN
793 * Entrypoints for generic asynch io:
794 * (these entrypoints are not very useful except in combination with *
795 * some of the other I/O model calls which can tell you which fds to
798 * Note that any adns call may cause adns to open and close fds, so
799 * you must call beforeselect or beforepoll again just before
800 * blocking, or you may not have an up-to-date list of it's fds.
803 int adns_processany(adns_state ads);
804 /* Gives adns flow-of-control for a bit. This will never block, and
805 * can be used with any threading/asynch-io model. If some error
806 * occurred which might cause an event loop to spin then the errno
810 int adns_processreadable(adns_state ads, int fd, const struct timeval *now);
811 int adns_processwriteable(adns_state ads, int fd, const struct timeval *now);
812 int adns_processexceptional(adns_state ads, int fd, const struct timeval *now);
813 /* Gives adns flow-of-control so that it can process incoming data
814 * from, or send outgoing data via, fd. Very like _processany. If it
815 * returns zero then fd will no longer be readable or writeable
816 * (unless of course more data has arrived since). adns will _only_
817 * use that fd and only in the manner specified, regardless of whether
818 * adns_if_noautosys was specified.
820 * adns_processexceptional should be called when select(2) reports an
821 * exceptional condition, or poll(2) reports POLLPRI.
823 * It is fine to call _processreabable or _processwriteable when the
824 * fd is not ready, or with an fd that doesn't belong to adns; it will
825 * then just return 0.
827 * If some error occurred which might prevent an event loop to spin
828 * then the errno value is returned.
831 void adns_processtimeouts(adns_state ads, const struct timeval *now);
832 /* Gives adns flow-of-control so that it can process any timeouts
833 * which might have happened. Very like _processreadable/writeable.
835 * now may be 0; if it isn't, *now must be the current time, recently
836 * obtained from gettimeofday.
839 void adns_firsttimeout(adns_state ads,
840 struct timeval **tv_mod, struct timeval *tv_buf,
842 /* Asks adns when it would first like the opportunity to time
843 * something out. now must be the current time, from gettimeofday.
845 * If tv_mod points to 0 then tv_buf must be non-null, and
846 * _firsttimeout will fill in *tv_buf with the time until the first
847 * timeout, and make *tv_mod point to tv_buf. If adns doesn't have
848 * anything that might need timing out it will leave *tv_mod as 0.
850 * If *tv_mod is not 0 then tv_buf is not used. adns will update
851 * *tv_mod if it has any earlier timeout, and leave it alone if it
854 * This call will not actually do any I/O, or change the fds that adns
855 * is using. It always succeeds and never blocks.
858 void adns_globalsystemfailure(adns_state ads);
859 /* If serious problem(s) happen which globally affect your ability to
860 * interact properly with adns, or adns's ability to function
861 * properly, you or adns can call this function.
863 * All currently outstanding queries will be made to fail with
864 * adns_s_systemfail, and adns will close any stream sockets it has
867 * This is used by adns, for example, if gettimeofday() fails.
868 * Without this the program's event loop might start to spin !
870 * This call will never block.
874 * Entrypoints for select-loop based asynch io:
877 void adns_beforeselect(adns_state ads, int *maxfd, fd_set *readfds,
878 fd_set *writefds, fd_set *exceptfds,
879 struct timeval **tv_mod, struct timeval *tv_buf,
880 const struct timeval *now);
881 /* Find out file descriptors adns is interested in, and when it would
882 * like the opportunity to time something out. If you do not plan to
883 * block then tv_mod may be 0. Otherwise, tv_mod and tv_buf are as
884 * for adns_firsttimeout. readfds, writefds, exceptfds and maxfd_io may
887 * If tv_mod is 0 on entry then this will never actually do any I/O,
888 * or change the fds that adns is using or the timeouts it wants. In
889 * any case it won't block, and it will set the timeout to zero if a
890 * query finishes in _beforeselect.
893 void adns_afterselect(adns_state ads, int maxfd, const fd_set *readfds,
894 const fd_set *writefds, const fd_set *exceptfds,
895 const struct timeval *now);
896 /* Gives adns flow-of-control for a bit; intended for use after
897 * select. This is just a fancy way of calling adns_processreadable/
898 * writeable/timeouts as appropriate, as if select had returned the
899 * data being passed. Always succeeds.
903 * Example calling sequence:
905 * adns_init _noautosys
911 * adns_submit / adns_check
917 * Entrypoints for poll-loop based asynch io:
921 /* In case your system doesn't have it or you forgot to include
922 * <sys/poll.h>, to stop the following declarations from causing
923 * problems. If your system doesn't have poll then the following
924 * entrypoints will not be defined in libadns. Sorry !
927 int adns_beforepoll(adns_state ads, struct pollfd *fds,
928 int *nfds_io, int *timeout_io,
929 const struct timeval *now);
930 /* Finds out which fd's adns is interested in, and when it would like
931 * to be able to time things out. This is in a form suitable for use
934 * On entry, usually fds should point to at least *nfds_io structs.
935 * adns will fill up to that many structs will information for poll,
936 * and record in *nfds_io how many structs it filled. If it wants to
937 * listen for more structs then *nfds_io will be set to the number
938 * required and _beforepoll will return ERANGE.
940 * You may call _beforepoll with fds==0 and *nfds_io 0, in which case
941 * adns will fill in the number of fds that it might be interested in
942 * in *nfds_io, and always return either 0 (if it is not interested in
943 * any fds) or ERANGE (if it is).
945 * NOTE that (unless now is 0) adns may acquire additional fds
946 * from one call to the next, so you must put adns_beforepoll in a
947 * loop, rather than assuming that the second call (with the buffer
948 * size requested by the first) will not return ERANGE.
950 * adns only ever sets POLLIN, POLLOUT and POLLPRI in its pollfd
951 * structs, and only ever looks at those bits. POLLPRI is required to
952 * detect TCP Urgent Data (which should not be used by a DNS server)
953 * so that adns can know that the TCP stream is now useless.
955 * In any case, *timeout_io should be a timeout value as for poll(2),
956 * which adns will modify downwards as required. If the caller does
957 * not plan to block then *timeout_io should be 0 on entry, or
958 * alternatively, timeout_io may be 0. (Alternatively, the caller may
959 * use _beforeselect with timeout_io==0 to find out about file
960 * descriptors, and use _firsttimeout is used to find out when adns
961 * might want to time something out.)
963 * adns_beforepoll will return 0 on success, and will not fail for any
964 * reason other than the fds buffer being too small (ERANGE).
966 * This call will never actually do any I/O. If you supply the
967 * current time it will not change the fds that adns is using or the
970 * In any case this call won't block.
973 #define ADNS_POLLFDS_RECOMMENDED 3
974 /* If you allocate an fds buf with at least RECOMMENDED entries then
975 * you are unlikely to need to enlarge it. You are recommended to do
976 * so if it's convenient. However, you must be prepared for adns to
977 * require more space than this.
980 void adns_afterpoll(adns_state ads, const struct pollfd *fds, int nfds,
981 const struct timeval *now);
982 /* Gives adns flow-of-control for a bit; intended for use after
983 * poll(2). fds and nfds should be the results from poll(). pollfd
984 * structs mentioning fds not belonging to adns will be ignored.
988 adns_status adns_rr_info(adns_rrtype type,
989 const char **rrtname_r, const char **fmtname_r,
991 const void *datap, char **data_r);
993 * Get information about a query type, or convert reply data to a
994 * textual form. type must be specified, and the official name of the
995 * corresponding RR type will be returned in *rrtname_r, and
996 * information about the processing style in *fmtname_r. The length
997 * of the table entry in an answer for that type will be returned in
998 * in *len_r. Any or all of rrtname_r, fmtname_r and len_r may be 0.
999 * If fmtname_r is non-null then *fmtname_r may be null on return,
1000 * indicating that no special processing is involved.
1002 * data_r be must be non-null iff datap is. In this case *data_r will
1003 * be set to point to a string pointing to a representation of the RR
1004 * data in master file format. (The owner name, timeout, class and
1005 * type will not be present - only the data part of the RR.) The
1006 * memory will have been obtained from malloc() and must be freed by
1009 * Usually this routine will succeed. Possible errors include:
1011 * adns_s_rrtypeunknown
1012 * adns_s_invaliddata (*datap contained garbage)
1013 * If an error occurs then no memory has been allocated,
1014 * and *rrtname_r, *fmtname_r, *len_r and *data_r are undefined.
1016 * There are some adns-invented data formats which are not official
1017 * master file formats. These include:
1019 * Mailboxes if __qtf_mail822: these are just included as-is.
1021 * Addresses (adns_rr_addr): these may be of pretty much any type.
1022 * The representation is in two parts: first, a word for the address
1023 * family (ie, in AF_XXX, the XXX), and then one or more items for the
1024 * address itself, depending on the format. For an IPv4 address the
1025 * syntax is INET followed by the dotted quad (from inet_ntoa).
1026 * Currently only IPv4 is supported.
1028 * Text strings (as in adns_rr_txt) appear inside double quotes, and
1029 * use \" and \\ to represent " and \, and \xHH to represent
1030 * characters not in the range 32-126.
1032 * Hostname with addresses (adns_rr_hostaddr): this consists of the
1033 * hostname, as usual, followed by the adns_status value, as an
1034 * abbreviation, and then a descriptive string (encoded as if it were
1035 * a piece of text), for the address lookup, followed by zero or more
1036 * addresses enclosed in ( and ). If the result was a temporary
1037 * failure, then a single ? appears instead of the ( ). If the
1038 * result was a permanent failure then an empty pair of parentheses
1039 * appears (which a space in between). For example, one of the NS
1040 * records for greenend.org.uk comes out like
1041 * ns.chiark.greenend.org.uk ok "OK" ( INET 195.224.76.132 )
1042 * an MX referring to a nonexistent host might come out like:
1043 * 50 sun2.nsfnet-relay.ac.uk nxdomain "No such domain" ( )
1044 * and if nameserver information is not available you might get:
1045 * dns2.spong.dyn.ml.org timeout "DNS query timed out" ?
1048 const char *adns_strerror(adns_status st);
1049 const char *adns_errabbrev(adns_status st);
1050 const char *adns_errtypeabbrev(adns_status st);
1051 /* Like strerror but for adns_status values. adns_errabbrev returns
1052 * the abbreviation of the error - eg, for adns_s_timeout it returns
1053 * "timeout". adns_errtypeabbrev returns the abbreviation of the
1054 * error class: ie, for values up to adns_s_max_XXX it will return the
1055 * string XXX. You MUST NOT call these functions with status values
1056 * not returned by the same adns library.
1060 } /* end of extern "C" */