3 * - adns user-visible API
8 * Copyright (C) 1997-2000,2003,2006 Ian Jackson
10 * It is part of adns, which is
11 * Copyright (C) 1997-2000,2003,2006 Ian Jackson
12 * Copyright (C) 1999-2000,2003,2006 Tony Finch
13 * Copyright (C) 1991 Massachusetts Institute of Technology
15 * This program is free software; you can redistribute it and/or modify
16 * it under the terms of the GNU General Public License as published by
17 * the Free Software Foundation; either version 2, or (at your option)
20 * This program is distributed in the hope that it will be useful,
21 * but WITHOUT ANY WARRANTY; without even the implied warranty of
22 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
23 * GNU General Public License for more details.
26 * For the benefit of certain LGPL'd `omnibus' software which
27 * provides a uniform interface to various things including adns, I
28 * make the following additional licence. I do this because the GPL
29 * would otherwise force either the omnibus software to be GPL'd or
30 * the adns-using part to be distributed separately.
32 * So: you may also redistribute and/or modify adns.h (but only the
33 * public header file adns.h and not any other part of adns) under the
34 * terms of the GNU Library General Public License as published by the
35 * Free Software Foundation; either version 2 of the License, or (at
36 * your option) any later version.
38 * Note that adns itself is GPL'd. Authors of adns-using applications
39 * with GPL-incompatible licences, and people who distribute adns with
40 * applications where the whole distribution is not GPL'd, are still
41 * likely to be in violation of the GPL. Anyone who wants to do this
42 * should contact Ian Jackson. Please note that to avoid encouraging
43 * people to infringe the GPL as it applies to the body of adns, Ian
44 * thinks that if you take advantage of the special exception to
45 * redistribute just adns.h under the LGPL, you should retain this
46 * paragraph in its place in the appropriate copyright statements.
49 * You should have received a copy of the GNU General Public License,
50 * or the GNU Library General Public License, as appropriate, along
51 * with this program; if not, write to the Free Software Foundation,
52 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
55 * $Id: adns.h,v 1.96 2006/08/09 11:16:59 ian Exp $
58 #ifndef ADNS_H_INCLUDED
59 #define ADNS_H_INCLUDED
64 #include <sys/types.h>
65 #include <sys/socket.h>
66 #include <netinet/in.h>
71 extern "C" { /* I really dislike this - iwj. */
74 /* 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, or
81 * `ADNS_FEATURE_MANYAF' to allow multiple address families; the default is
82 * currently to stick with AF_INET only, but this is likely to change in a
83 * later release of ADNS.
85 #if !defined(ADNS_FEATURE_IPV4ONLY) && !defined(ADNS_FEATURE_MANYAF)
86 # define ADNS_FEATURE_IPV4ONLY
87 #elif defined(ADNS_FEATURE_IPV4ONLY) && defined(ADNS_FEATURE_MANYAF)
88 # error "Feature flags ADNS_FEATURE_IPV4ONLY and ..._MANYAF are incompatible"
91 /* All struct in_addr anywhere in adns are in NETWORK byte order. */
93 typedef struct adns__state *adns_state;
94 typedef struct adns__query *adns_query;
96 typedef enum { /* In general, or together the desired flags: */
97 adns_if_none= 0x0000,/* no flags. nicer than 0 for some compilers */
98 adns_if_noenv= 0x0001,/* do not look at environment */
99 adns_if_noerrprint= 0x0002,/* never print to stderr (_debug overrides) */
100 adns_if_noserverwarn=0x0004,/* do not warn to stderr about duff servers etc */
101 adns_if_debug= 0x0008,/* enable all output to stderr plus debug msgs */
102 adns_if_logpid= 0x0080,/* include pid in diagnostic output */
103 adns_if_noautosys= 0x0010,/* do not make syscalls at every opportunity */
104 adns_if_eintr= 0x0020,/* allow _wait and _synchronous to return EINTR */
105 adns_if_nosigpipe= 0x0040,/* applic has SIGPIPE ignored, do not protect */
106 adns_if_checkc_entex=0x0100,/* consistency checks on entry/exit to adns fns */
107 adns_if_checkc_freq= 0x0300,/* consistency checks very frequently (slow!) */
109 adns_if_af_v4only= 0x0400,/* only return IPv4 addresses, given the choice */
110 adns_if_af_v6only= 0x0800,/* only return IPv6 addresses, ... */
111 adns_if_afmask= adns_if_af_v4only|adns_if_af_v6only
112 /* Only set one of these. They are policy flags, and overridden by the
113 * adns_af:... options in resolv.conf. If the adns_qf_ipv... query
114 * flags are incompatible with these settings (in the sense that no
115 * address families are permitted at all) then the query flags take
116 * precedence; otherwise only records which satisfy all of the stated
117 * requirements are allowed.
121 typedef enum { /* In general, or together the desired flags: */
122 adns_qf_none= 0x00000000,/* no flags */
123 adns_qf_search= 0x00000001,/* use the searchlist */
124 adns_qf_usevc= 0x00000002,/* use a virtual circuit (TCP conn) */
125 adns_qf_owner= 0x00000004,/* fill in the owner field in the answer */
126 adns_qf_quoteok_query= 0x00000010,/* allow special chars in query domain */
127 adns_qf_quoteok_cname= 0x00000000,/* ... in CNAME we go via (now default) */
128 adns_qf_quoteok_anshost=0x00000040,/* ... in things supposedly hostnames */
129 adns_qf_quotefail_cname=0x00000080,/* refuse if quote-req chars in CNAME we go via */
130 adns_qf_cname_loose= 0x00000100,/* allow refs to CNAMEs - without, get _s_cname */
131 adns_qf_cname_forbid= 0x00000200,/* don't follow CNAMEs, instead give _s_cname */
132 adns_qf_ipv4_only= 0x00000400,/* only ever return IPv4 addresses */
133 adns_qf_ipv6_only= 0x00000800,/* ... and don't bother looking for IPv4 */
134 adns_qf_ipv6_ok= 0x00000c00,/* returning IPv6 addresses is acceptable */
135 adns_qf_domapv4= 0x00001000,/* ... any IPv4 addresses should be v6-mapped */
136 adns_qf_ipv6_mapv4= adns_qf_ipv6_ok|adns_qf_domapv4,
137 adns__qf_afmask= 0x00001c00,/* all the above flag bits */
138 adns__qf_internalmask= 0x0ff00000
142 adns_rrt_typemask= 0x0ffff,
143 adns_rrt_reprmask= 0xffffff,
144 adns__qtf_deref_bit=0x10000,/* internal version of ..._deref below */
145 adns__qtf_mail822= 0x20000,/* return mailboxes in RFC822 rcpt field fmt */
147 adns_r_unknown= 0x40000,
148 /* To use this, ask for records of type <rr-type-code>|adns_r_unknown.
149 * adns will not process the RDATA - you'll get adns_rr_byteblocks,
150 * where the int is the length and the unsigned char* points to the
151 * data. String representation of the RR data (by adns_rrinfo) is as in
152 * RFC3597. adns_rr_info will not return the type name in *rrtname_r
153 * (due to memory management problems); *fmtname_r will be set to
156 * Do not specify adns_r_unknown along with a known RR type which
157 * requires domain name uncompression (see RFC3597 s4); domain names
158 * will not be uncompressed and the resulting data would be useless.
159 * Asking for meta-RR types via adns_r_unknown will not work properly
160 * either and may make adns complain about server misbehaviour, so don't
163 * Don't forget adns_qf_quoteok if that's what you want. */
165 adns__qtf_bigaddr=0x1000000,/* use the new larger sockaddr union */
166 adns__qtf_manyaf= 0x2000000,/* permitted to return multiple address families */
168 adns__qtf_deref= adns__qtf_deref_bit|adns__qtf_bigaddr
169 #ifdef ADNS_FEATURE_MANYAF
172 ,/* dereference domains; perhaps get extra data */
179 adns_r_ns= adns_r_ns_raw|adns__qtf_deref,
184 adns_r_soa= adns_r_soa_raw|adns__qtf_mail822,
186 adns_r_ptr_raw= 12, /* do not mind PTR with wrong or missing A */
187 adns_r_ptr= adns_r_ptr_raw|adns__qtf_deref,
192 adns_r_mx= adns_r_mx_raw|adns__qtf_deref,
197 adns_r_rp= adns_r_rp_raw|adns__qtf_mail822,
201 /* For SRV records, query domain without _qf_quoteok_query must look
202 * as expected from SRV RFC with hostname-like Name. _With_
203 * _quoteok_query, any query domain is allowed. */
205 adns_r_srv= adns_r_srv_raw|adns__qtf_deref,
207 adns_r_addr= adns_r_a|adns__qtf_deref
212 * In queries without qf_quoteok_*, all domains must have standard
213 * legal syntax, or you get adns_s_querydomainvalid (if the query
214 * domain contains bad characters) or adns_s_answerdomaininvalid (if
215 * the answer contains bad characters).
217 * In queries _with_ qf_quoteok_*, domains in the query or response
218 * may contain any characters, quoted according to RFC1035 5.1. On
219 * input to adns, the char* is a pointer to the interior of a "
220 * delimited string, except that " may appear in it unquoted. On
221 * output, the char* is a pointer to a string which would be legal
222 * either inside or outside " delimiters; any character which isn't
223 * legal in a hostname (ie alphanumeric or hyphen) or one of _ / +
224 * (the three other punctuation characters commonly abused in domain
225 * names) will be quoted, as \X if it is a printing ASCII character or
228 * If the query goes via a CNAME then the canonical name (ie, the
229 * thing that the CNAME record refers to) is usually allowed to
230 * contain any characters, which will be quoted as above. With
231 * adns_qf_quotefail_cname you get adns_s_answerdomaininvalid when
232 * this happens. (This is a change from version 0.4 and earlier, in
233 * which failing the query was the default, and you had to say
234 * adns_qf_quoteok_cname to avoid this; that flag is now deprecated.)
236 * In version 0.4 and earlier, asking for _raw records containing
237 * mailboxes without specifying _qf_quoteok_anshost was silly. This
238 * is no longer the case. In this version only parts of responses
239 * that are actually supposed to be hostnames will be refused by
240 * default if quote-requiring characters are found.
244 * If you ask for an RR which contains domains which are actually
245 * encoded mailboxes, and don't ask for the _raw version, then adns
246 * returns the mailbox formatted suitably for an RFC822 recipient
247 * header field. The particular format used is that if the mailbox
248 * requires quoting according to the rules in RFC822 then the
249 * local-part is quoted in double quotes, which end at the next
250 * unescaped double quote (\ is the escape char, and is doubled, and
251 * is used to escape only \ and "). If the local-part is legal
252 * without quoting according to RFC822, it is presented as-is. In any
253 * case the local-part is followed by an @ and the domain. The domain
254 * will not contain any characters not legal in hostnames.
256 * Unquoted local-parts may contain any printing 7-bit ASCII
257 * except the punctuation characters ( ) < > @ , ; : \ " [ ]
258 * I.e. they may contain alphanumerics, and the following
259 * punctuation characters: ! # % ^ & * - _ = + { } .
261 * adns will reject local parts containing control characters (byte
262 * values 0-31, 127-159, and 255) - these appear to be legal according
263 * to RFC822 (at least 0-127) but are clearly a bad idea. RFC1035
264 * syntax does not make any distinction between a single RFC822
265 * quoted-string containing full stops, and a series of quoted-strings
266 * separated by full stops; adns will return anything that isn't all
267 * valid atoms as a single quoted-string. RFC822 does not allow
268 * high-bit-set characters at all, but adns does allow them in
269 * local-parts, treating them as needing quoting.
271 * If you ask for the domain with _raw then _no_ checking is done
272 * (even on the host part, regardless of adns_qf_quoteok_anshost), and
273 * you just get the domain name in master file format.
275 * If no mailbox is supplied the returned string will be `.' in either
282 /* locally induced errors */
284 adns_s_unknownrrtype,
287 adns_s_max_localfail= 29,
289 /* remotely induced errors, detected locally */
293 adns_s_invalidresponse,
294 adns_s_unknownformat,
296 adns_s_max_remotefail= 59,
298 /* remotely induced errors, reported by remote server to us */
299 adns_s_rcodeservfail,
300 adns_s_rcodeformaterror,
301 adns_s_rcodenotimplemented,
305 adns_s_max_tempfail= 99,
307 /* remote configuration errors */
308 adns_s_inconsistent, /* PTR gives domain whose A does not exist and match */
309 adns_s_prohibitedcname, /* CNAME, but eg A expected (not if _qf_loosecname) */
310 adns_s_answerdomaininvalid,
311 adns_s_answerdomaintoolong,
314 adns_s_max_misconfig= 199,
316 /* permanent problems with the query */
317 adns_s_querydomainwrong,
318 adns_s_querydomaininvalid,
319 adns_s_querydomaintoolong,
321 adns_s_max_misquery= 299,
323 /* permanent errors */
327 adns_s_max_permfail= 499
333 struct sockaddr_in inet;
334 } adns_sockaddr_v4only;
338 struct sockaddr_in inet;
339 struct sockaddr_in6 inet6;
340 char adns__padding[240]; /* Good idea? I'm inclined to think not. */
350 adns_sockaddr_v4only addr;
351 } adns_rr_addr_v4only;
356 int naddrs; /* temp fail => -1, perm fail => 0, s_ok => >0 */
367 } adns_rr_inthostaddr;
370 /* Used both for mx_raw, in which case i is the preference and str
371 * the domain, and for txt, in which case each entry has i for the
372 * `text' length, and str for the data (which will have had an extra
373 * nul appended so that if it was plain text it is now a
374 * null-terminated string).
381 adns_rr_intstr array[2];
382 } adns_rr_intstrpair;
386 unsigned long serial, refresh, retry, expire, minimum;
390 int priority, weight, port;
395 int priority, weight, port;
406 char *cname; /* always NULL if query was for CNAME records */
407 char *owner; /* only set if req'd in query flags; maybe 0 on error anyway */
408 adns_rrtype type; /* guaranteed to be same as in query */
409 time_t expires;/*abs time. def only if _s_ok, nxdomain or nodata. NOT TTL!*/
410 int nrrs, rrsz; /* nrrs is 0 if an error occurs */
413 unsigned char *bytes;
414 char *(*str); /* ns_raw, cname, ptr, ptr_raw */
415 adns_rr_intstr *(*manyistr); /* txt (list strs ends with i=-1, str=0)*/
416 adns_rr_addr *addr; /* addr */
417 struct in_addr *inaddr; /* a */
418 struct in6_addr *in6addr; /* aaaa */
419 adns_rr_hostaddr *hostaddr; /* ns */
420 adns_rr_intstrpair *intstrpair; /* hinfo */
421 adns_rr_strpair *strpair; /* rp, rp_raw */
422 adns_rr_inthostaddr *inthostaddr;/* mx */
423 adns_rr_intstr *intstr; /* mx_raw */
424 adns_rr_soa *soa; /* soa, soa_raw */
425 adns_rr_srvraw *srvraw; /* srv_raw */
426 adns_rr_srvha *srvha;/* srv */
427 adns_rr_byteblock *byteblock; /* ...|unknown */
431 /* Memory management:
432 * adns_state and adns_query are actually pointers to malloc'd state;
433 * On submission questions are copied, including the owner domain;
434 * Answers are malloc'd as a single piece of memory; pointers in the
435 * answer struct point into further memory in the answer.
437 * Must always be non-null pointer;
438 * If *query_io is 0 to start with then any query may be returned;
439 * If *query_io is !0 adns_query then only that query may be returned.
440 * If the call is successful, *query_io, *answer_r, and *context_r
443 * Return values are 0 or an errno value.
445 * For _init, _init_strcfg, _submit and _synchronous, system errors
446 * (eg, failure to create sockets, malloc failure, etc.) return errno
447 * values. EINVAL from _init et al means the configuration file
448 * is erroneous and cannot be parsed.
450 * For _wait and _check failures are reported in the answer
451 * structure, and only 0, ESRCH or (for _check) EAGAIN is
452 * returned: if no (appropriate) requests are done adns_check returns
453 * EAGAIN; if no (appropriate) requests are outstanding both
454 * adns_query and adns_wait return ESRCH.
456 * Additionally, _wait can return EINTR if you set adns_if_eintr.
458 * All other errors (nameserver failure, timed out connections, &c)
459 * are returned in the status field of the answer. After a
460 * successful _wait or _check, if status is nonzero then nrrs will be
461 * 0, otherwise it will be >0. type will always be the type
466 * adns does not use any static modifiable state, so it
467 * is safe to call adns_init several times and then use the
468 * resulting adns_states concurrently.
469 * However, it is NOT safe to make simultaneous calls into
470 * adns using the same adns_state; a single adns_state must be used
471 * only by one thread at a time. You can solve this problem by
472 * having one adns_state per thread, or if that isn't feasible, you
473 * could maintain a pool of adns_states. Unfortunately neither of
474 * these approaches has optimal performance.
477 int adns_init(adns_state *newstate_r, adns_initflags flags,
478 FILE *diagfile /*0=>stderr*/);
480 int adns_init_strcfg(adns_state *newstate_r, adns_initflags flags,
481 FILE *diagfile /*0=>discard*/, const char *configtext);
483 typedef void adns_logcallbackfn(adns_state ads, void *logfndata,
484 const char *fmt, va_list al);
485 /* Will be called perhaps several times for each message; when the
486 * message is complete, the string implied by fmt and al will end in
487 * a newline. Log messages start with `adns debug:' or `adns
488 * warning:' or `adns:' (for errors), or `adns debug [PID]:'
489 * etc. if adns_if_logpid is set. */
491 int adns_init_logfn(adns_state *newstate_r, adns_initflags flags,
492 const char *configtext /*0=>use default config files*/,
493 adns_logcallbackfn *logfn /*0=>logfndata is a FILE* */,
494 void *logfndata /*0 with logfn==0 => discard*/);
497 * adns_init reads /etc/resolv.conf, which is expected to be (broadly
498 * speaking) in the format expected by libresolv, and then
499 * /etc/resolv-adns.conf if it exists. adns_init_strcfg is instead
500 * passed a string which is interpreted as if it were the contents of
501 * resolv.conf or resolv-adns.conf. In general, configuration which
502 * is set later overrides any that is set earlier.
504 * Standard directives understood in resolv[-adns].conf:
506 * nameserver <address>
507 * Must be followed by the IP address of a nameserver. Several
508 * nameservers may be specified, and they will be tried in the order
509 * found. There is a compiled in limit, currently 5, on the number
510 * of nameservers. (libresolv supports only 3 nameservers.)
512 * search <domain> ...
513 * Specifies the search list for queries which specify
514 * adns_qf_search. This is a list of domains to append to the query
515 * domain. The query domain will be tried as-is either before all
516 * of these or after them, depending on the ndots option setting
520 * This is present only for backward compatibility with obsolete
521 * versions of libresolv. It should not be used, and is interpreted
522 * by adns as if it were `search' - note that this is subtly
523 * different to libresolv's interpretation of this directive.
525 * sortlist <addr>/<mask> ...
526 * Should be followed by a sequence of IP-address and netmask pairs,
527 * separated by spaces. They may be specified as
528 * eg. 172.30.206.0/24 or 172.30.206.0/255.255.255.0. Currently up
529 * to 15 pairs may be specified (but note that libresolv only
530 * supports up to 10).
533 * Should followed by one or more options, separated by spaces.
534 * Each option consists of an option name, followed by optionally
535 * a colon and a value. Options are listed below.
537 * Non-standard directives understood in resolv[-adns].conf:
540 * Clears the list of nameservers, so that further nameserver lines
541 * start again from the beginning.
544 * The specified file will be read.
546 * Additionally, adns will ignore lines in resolv[-adns].conf which
549 * Standard options understood:
552 * Enables debugging output from the resolver, which will be written
556 * Affects whether queries with adns_qf_search will be tried first
557 * without adding domains from the searchlist, or whether the bare
558 * query domain will be tried last. Queries which contain at least
559 * <count> dots will be tried bare first. The default is 1.
561 * Non-standard options understood:
566 * Changes the consistency checking frequency; this overrides the
567 * setting of adns_if_check_entex, adns_if_check_freq, or neither,
568 * in the flags passed to adns_init.
573 * Controls whether ADNS looks for IPv4 (A records) and IPv6 (AAAA
574 * records) addresses when it's trying to build a socket address.
575 * The default is `any' which means to allow both. The `sortlist'
576 * directive can be used to control the relative preference of IPv4
577 * and IPv6 addresses if both are returned for the same query.
578 * These override the corresponding init flags (covered by
581 * There are a number of environment variables which can modify the
582 * behaviour of adns. They take effect only if adns_init is used, and
583 * the caller of adns_init can disable them using adns_if_noenv. In
584 * each case there is both a FOO and an ADNS_FOO; the latter is
585 * interpreted later so that it can override the former. Unless
586 * otherwise stated, environment variables are interpreted after
587 * resolv[-adns].conf are read, in the order they are listed here.
589 * RES_CONF, ADNS_RES_CONF
590 * A filename, whose contets are in the format of resolv.conf.
592 * RES_CONF_TEXT, ADNS_RES_CONF_TEXT
593 * A string in the format of resolv.conf.
595 * RES_OPTIONS, ADNS_RES_OPTIONS
596 * These are parsed as if they appeared in the `options' line of a
597 * resolv.conf. In addition to being parsed at this point in the
598 * sequence, they are also parsed at the very beginning before
599 * resolv.conf or any other environment variables are read, so that
600 * any debug option can affect the processing of the configuration.
602 * LOCALDOMAIN, ADNS_LOCALDOMAIN
603 * These are interpreted as if their contents appeared in a `search'
604 * line in resolv.conf.
607 int adns_synchronous(adns_state ads,
610 adns_queryflags flags,
611 adns_answer **answer_r);
613 /* NB: if you set adns_if_noautosys then _submit and _check do not
614 * make any system calls; you must use some of the asynch-io event
615 * processing functions to actually get things to happen.
618 int adns_submit(adns_state ads,
621 adns_queryflags flags,
623 adns_query *query_r);
625 /* The owner should be quoted in master file format. */
627 int adns_check(adns_state ads,
628 adns_query *query_io,
629 adns_answer **answer_r,
632 int adns_wait(adns_state ads,
633 adns_query *query_io,
634 adns_answer **answer_r,
637 /* same as adns_wait but uses poll(2) internally */
638 int adns_wait_poll(adns_state ads,
639 adns_query *query_io,
640 adns_answer **answer_r,
643 void adns_cancel(adns_query query);
645 /* The adns_query you get back from _submit is valid (ie, can be
646 * legitimately passed into adns functions) until it is returned by
647 * adns_check or adns_wait, or passed to adns_cancel. After that it
648 * must not be used. You can rely on it not being reused until the
649 * first adns_submit or _transact call using the same adns_state after
650 * it became invalid, so you may compare it for equality with other
651 * query handles until you next call _query or _transact.
653 * _submit and _synchronous return ENOSYS if they don't understand the
657 int adns_submit_reverse(adns_state ads,
658 const struct sockaddr *addr,
660 adns_queryflags flags,
662 adns_query *query_r);
663 /* type must be _r_ptr or _r_ptr_raw. _qf_search is ignored.
664 * addr->sa_family must be AF_INET or you get ENOSYS.
667 int adns_submit_reverse_any(adns_state ads,
668 const struct sockaddr *addr,
671 adns_queryflags flags,
673 adns_query *query_r);
674 /* For RBL-style reverse `zone's; look up
675 * <reversed-address>.<zone>
676 * Any type is allowed. _qf_search is ignored.
677 * addr->sa_family must be AF_INET or you get ENOSYS.
680 void adns_finish(adns_state ads);
681 /* You may call this even if you have queries outstanding;
682 * they will be cancelled.
685 #define ADNS_ADDR2TEXT_BUFLEN (INET6_ADDRSTRLEN +1/*%*/ +9/*uint32*/ +1/*nul*/)
687 int adns_text2addr(const char *addr, uint16_t port, struct sockaddr *sa,
688 socklen_t *salen /* set if OK or ENOSPC; otherwise undef */);
689 int adns_addr2text(const struct sockaddr *sa,
690 char *addr_buffer, int *addr_buflen /* set iff ENOSPC */,
691 int *port_r /* may be 0 */);
692 /* Error return values are:
693 * EAFNOSUPPORT addr2text only
694 * EINVAL text2addr only: addr has invalid syntax
695 * ENOSPC only if *buflen < _BUFLEN or *salen < sizeof(adns_sockaddr)
696 * Extra errors are possible from text2addr if addr specifies a scope
697 * name suffix (ie, it has a "%") and the scope suffix is not numeric:
698 * ENOSYS address is not link local
699 * ENXIO if_nametoindex said it wasn't a valid name
700 * EIO if_nametoindex went crazy (adns prints a message to stderr)
701 * any other if_nametoindex failed
702 * port is always in host byte order and is simply copied to and
703 * from the appropriate sockaddr field (byteswapped as necessary).
706 void adns_forallqueries_begin(adns_state ads);
707 adns_query adns_forallqueries_next(adns_state ads, void **context_r);
708 /* Iterator functions, which you can use to loop over the outstanding
709 * (submitted but not yet successfuly checked/waited) queries.
711 * You can only have one iteration going at once. You may call _begin
712 * at any time; after that, an iteration will be in progress. You may
713 * only call _next when an iteration is in progress - anything else
714 * may coredump. The iteration remains in progress until _next
715 * returns 0, indicating that all the queries have been walked over,
716 * or ANY other adns function is called with the same adns_state (or a
717 * query in the same adns_state). There is no need to explicitly
718 * finish an iteration.
720 * context_r may be 0. *context_r may not be set when _next returns 0.
723 void adns_checkconsistency(adns_state ads, adns_query qu);
724 /* Checks the consistency of adns's internal data structures.
725 * If any error is found, the program will abort().
726 * You may pass 0 for qu; if you pass non-null then additional checks
727 * are done to make sure that qu is a valid query.
731 * Example expected/legal calling sequence for submit/check/wait:
737 * adns_check 3 -> EAGAIN
745 * Entrypoints for generic asynch io:
746 * (these entrypoints are not very useful except in combination with *
747 * some of the other I/O model calls which can tell you which fds to
750 * Note that any adns call may cause adns to open and close fds, so
751 * you must call beforeselect or beforepoll again just before
752 * blocking, or you may not have an up-to-date list of it's fds.
755 int adns_processany(adns_state ads);
756 /* Gives adns flow-of-control for a bit. This will never block, and
757 * can be used with any threading/asynch-io model. If some error
758 * occurred which might cause an event loop to spin then the errno
762 int adns_processreadable(adns_state ads, int fd, const struct timeval *now);
763 int adns_processwriteable(adns_state ads, int fd, const struct timeval *now);
764 int adns_processexceptional(adns_state ads, int fd, const struct timeval *now);
765 /* Gives adns flow-of-control so that it can process incoming data
766 * from, or send outgoing data via, fd. Very like _processany. If it
767 * returns zero then fd will no longer be readable or writeable
768 * (unless of course more data has arrived since). adns will _only_
769 * use that fd and only in the manner specified, regardless of whether
770 * adns_if_noautosys was specified.
772 * adns_processexceptional should be called when select(2) reports an
773 * exceptional condition, or poll(2) reports POLLPRI.
775 * It is fine to call _processreabable or _processwriteable when the
776 * fd is not ready, or with an fd that doesn't belong to adns; it will
777 * then just return 0.
779 * If some error occurred which might prevent an event loop to spin
780 * then the errno value is returned.
783 void adns_processtimeouts(adns_state ads, const struct timeval *now);
784 /* Gives adns flow-of-control so that it can process any timeouts
785 * which might have happened. Very like _processreadable/writeable.
787 * now may be 0; if it isn't, *now must be the current time, recently
788 * obtained from gettimeofday.
791 void adns_firsttimeout(adns_state ads,
792 struct timeval **tv_mod, struct timeval *tv_buf,
794 /* Asks adns when it would first like the opportunity to time
795 * something out. now must be the current time, from gettimeofday.
797 * If tv_mod points to 0 then tv_buf must be non-null, and
798 * _firsttimeout will fill in *tv_buf with the time until the first
799 * timeout, and make *tv_mod point to tv_buf. If adns doesn't have
800 * anything that might need timing out it will leave *tv_mod as 0.
802 * If *tv_mod is not 0 then tv_buf is not used. adns will update
803 * *tv_mod if it has any earlier timeout, and leave it alone if it
806 * This call will not actually do any I/O, or change the fds that adns
807 * is using. It always succeeds and never blocks.
810 void adns_globalsystemfailure(adns_state ads);
811 /* If serious problem(s) happen which globally affect your ability to
812 * interact properly with adns, or adns's ability to function
813 * properly, you or adns can call this function.
815 * All currently outstanding queries will be made to fail with
816 * adns_s_systemfail, and adns will close any stream sockets it has
819 * This is used by adns, for example, if gettimeofday() fails.
820 * Without this the program's event loop might start to spin !
822 * This call will never block.
826 * Entrypoints for select-loop based asynch io:
829 void adns_beforeselect(adns_state ads, int *maxfd, fd_set *readfds,
830 fd_set *writefds, fd_set *exceptfds,
831 struct timeval **tv_mod, struct timeval *tv_buf,
832 const struct timeval *now);
833 /* Find out file descriptors adns is interested in, and when it would
834 * like the opportunity to time something out. If you do not plan to
835 * block then tv_mod may be 0. Otherwise, tv_mod and tv_buf are as
836 * for adns_firsttimeout. readfds, writefds, exceptfds and maxfd_io may
839 * If tv_mod is 0 on entry then this will never actually do any I/O,
840 * or change the fds that adns is using or the timeouts it wants. In
841 * any case it won't block, and it will set the timeout to zero if a
842 * query finishes in _beforeselect.
845 void adns_afterselect(adns_state ads, int maxfd, const fd_set *readfds,
846 const fd_set *writefds, const fd_set *exceptfds,
847 const struct timeval *now);
848 /* Gives adns flow-of-control for a bit; intended for use after
849 * select. This is just a fancy way of calling adns_processreadable/
850 * writeable/timeouts as appropriate, as if select had returned the
851 * data being passed. Always succeeds.
855 * Example calling sequence:
857 * adns_init _noautosys
863 * adns_submit / adns_check
869 * Entrypoints for poll-loop based asynch io:
873 /* In case your system doesn't have it or you forgot to include
874 * <sys/poll.h>, to stop the following declarations from causing
875 * problems. If your system doesn't have poll then the following
876 * entrypoints will not be defined in libadns. Sorry !
879 int adns_beforepoll(adns_state ads, struct pollfd *fds,
880 int *nfds_io, int *timeout_io,
881 const struct timeval *now);
882 /* Finds out which fd's adns is interested in, and when it would like
883 * to be able to time things out. This is in a form suitable for use
886 * On entry, usually fds should point to at least *nfds_io structs.
887 * adns will fill up to that many structs will information for poll,
888 * and record in *nfds_io how many structs it filled. If it wants to
889 * listen for more structs then *nfds_io will be set to the number
890 * required and _beforepoll will return ERANGE.
892 * You may call _beforepoll with fds==0 and *nfds_io 0, in which case
893 * adns will fill in the number of fds that it might be interested in
894 * in *nfds_io, and always return either 0 (if it is not interested in
895 * any fds) or ERANGE (if it is).
897 * NOTE that (unless now is 0) adns may acquire additional fds
898 * from one call to the next, so you must put adns_beforepoll in a
899 * loop, rather than assuming that the second call (with the buffer
900 * size requested by the first) will not return ERANGE.
902 * adns only ever sets POLLIN, POLLOUT and POLLPRI in its pollfd
903 * structs, and only ever looks at those bits. POLLPRI is required to
904 * detect TCP Urgent Data (which should not be used by a DNS server)
905 * so that adns can know that the TCP stream is now useless.
907 * In any case, *timeout_io should be a timeout value as for poll(2),
908 * which adns will modify downwards as required. If the caller does
909 * not plan to block then *timeout_io should be 0 on entry, or
910 * alternatively, timeout_io may be 0. (Alternatively, the caller may
911 * use _beforeselect with timeout_io==0 to find out about file
912 * descriptors, and use _firsttimeout is used to find out when adns
913 * might want to time something out.)
915 * adns_beforepoll will return 0 on success, and will not fail for any
916 * reason other than the fds buffer being too small (ERANGE).
918 * This call will never actually do any I/O. If you supply the
919 * current time it will not change the fds that adns is using or the
922 * In any case this call won't block.
925 #define ADNS_POLLFDS_RECOMMENDED 3
926 /* If you allocate an fds buf with at least RECOMMENDED entries then
927 * you are unlikely to need to enlarge it. You are recommended to do
928 * so if it's convenient. However, you must be prepared for adns to
929 * require more space than this.
932 void adns_afterpoll(adns_state ads, const struct pollfd *fds, int nfds,
933 const struct timeval *now);
934 /* Gives adns flow-of-control for a bit; intended for use after
935 * poll(2). fds and nfds should be the results from poll(). pollfd
936 * structs mentioning fds not belonging to adns will be ignored.
940 adns_status adns_rr_info(adns_rrtype type,
941 const char **rrtname_r, const char **fmtname_r,
943 const void *datap, char **data_r);
945 * Get information about a query type, or convert reply data to a
946 * textual form. type must be specified, and the official name of the
947 * corresponding RR type will be returned in *rrtname_r, and
948 * information about the processing style in *fmtname_r. The length
949 * of the table entry in an answer for that type will be returned in
950 * in *len_r. Any or all of rrtname_r, fmtname_r and len_r may be 0.
951 * If fmtname_r is non-null then *fmtname_r may be null on return,
952 * indicating that no special processing is involved.
954 * data_r be must be non-null iff datap is. In this case *data_r will
955 * be set to point to a string pointing to a representation of the RR
956 * data in master file format. (The owner name, timeout, class and
957 * type will not be present - only the data part of the RR.) The
958 * memory will have been obtained from malloc() and must be freed by
961 * Usually this routine will succeed. Possible errors include:
963 * adns_s_rrtypeunknown
964 * adns_s_invaliddata (*datap contained garbage)
965 * If an error occurs then no memory has been allocated,
966 * and *rrtname_r, *fmtname_r, *len_r and *data_r are undefined.
968 * There are some adns-invented data formats which are not official
969 * master file formats. These include:
971 * Mailboxes if __qtf_mail822: these are just included as-is.
973 * Addresses (adns_rr_addr): these may be of pretty much any type.
974 * The representation is in two parts: first, a word for the address
975 * family (ie, in AF_XXX, the XXX), and then one or more items for the
976 * address itself, depending on the format. For an IPv4 address the
977 * syntax is INET followed by the dotted quad (from inet_ntoa).
978 * Currently only IPv4 is supported.
980 * Text strings (as in adns_rr_txt) appear inside double quotes, and
981 * use \" and \\ to represent " and \, and \xHH to represent
982 * characters not in the range 32-126.
984 * Hostname with addresses (adns_rr_hostaddr): this consists of the
985 * hostname, as usual, followed by the adns_status value, as an
986 * abbreviation, and then a descriptive string (encoded as if it were
987 * a piece of text), for the address lookup, followed by zero or more
988 * addresses enclosed in ( and ). If the result was a temporary
989 * failure, then a single ? appears instead of the ( ). If the
990 * result was a permanent failure then an empty pair of parentheses
991 * appears (which a space in between). For example, one of the NS
992 * records for greenend.org.uk comes out like
993 * ns.chiark.greenend.org.uk ok "OK" ( INET 195.224.76.132 )
994 * an MX referring to a nonexistent host might come out like:
995 * 50 sun2.nsfnet-relay.ac.uk nxdomain "No such domain" ( )
996 * and if nameserver information is not available you might get:
997 * dns2.spong.dyn.ml.org timeout "DNS query timed out" ?
1000 const char *adns_strerror(adns_status st);
1001 const char *adns_errabbrev(adns_status st);
1002 const char *adns_errtypeabbrev(adns_status st);
1003 /* Like strerror but for adns_status values. adns_errabbrev returns
1004 * the abbreviation of the error - eg, for adns_s_timeout it returns
1005 * "timeout". adns_errtypeabbrev returns the abbreviation of the
1006 * error class: ie, for values up to adns_s_max_XXX it will return the
1007 * string XXX. You MUST NOT call these functions with status values
1008 * not returned by the same adns library.
1012 } /* end of extern "C" */