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!) */
110 typedef enum { /* In general, or together the desired flags: */
111 adns_qf_none
= 0x00000000,/* no flags */
112 adns_qf_search
= 0x00000001,/* use the searchlist */
113 adns_qf_usevc
= 0x00000002,/* use a virtual circuit (TCP conn) */
114 adns_qf_owner
= 0x00000004,/* fill in the owner field in the answer */
115 adns_qf_quoteok_query
= 0x00000010,/* allow special chars in query domain */
116 adns_qf_quoteok_cname
= 0x00000000,/* ... in CNAME we go via (now default) */
117 adns_qf_quoteok_anshost
=0x00000040,/* ... in things supposedly hostnames */
118 adns_qf_quotefail_cname
=0x00000080,/* refuse if quote-req chars in CNAME we go via */
119 adns_qf_cname_loose
= 0x00000100,/* allow refs to CNAMEs - without, get _s_cname */
120 adns_qf_cname_forbid
= 0x00000200,/* don't follow CNAMEs, instead give _s_cname */
121 adns_qf_ipv4_only
= 0x00000400,/* only ever return IPv4 addresses */
122 adns_qf_ipv6_only
= 0x00000800,/* ... and don't bother looking for IPv4 */
123 adns_qf_ipv6_ok
= 0x00000c00,/* returning IPv6 addresses is acceptable */
124 adns_qf_domapv4
= 0x00001000,/* ... any IPv4 addresses should be v6-mapped */
125 adns_qf_ipv6_mapv4
= adns_qf_ipv6_ok
|adns_qf_domapv4
,
126 adns__qf_afmask
= 0x00001c00,/* all the above flag bits */
127 adns__qf_internalmask
= 0x0ff00000
131 adns_rrt_typemask
= 0x0ffff,
132 adns_rrt_reprmask
= 0xffffff,
133 adns__qtf_deref_bit
=0x10000,/* internal version of ..._deref below */
134 adns__qtf_mail822
= 0x20000,/* return mailboxes in RFC822 rcpt field fmt */
136 adns_r_unknown
= 0x40000,
137 /* To use this, ask for records of type <rr-type-code>|adns_r_unknown.
138 * adns will not process the RDATA - you'll get adns_rr_byteblocks,
139 * where the int is the length and the unsigned char* points to the
140 * data. String representation of the RR data (by adns_rrinfo) is as in
141 * RFC3597. adns_rr_info will not return the type name in *rrtname_r
142 * (due to memory management problems); *fmtname_r will be set to
145 * Do not specify adns_r_unknown along with a known RR type which
146 * requires domain name uncompression (see RFC3597 s4); domain names
147 * will not be uncompressed and the resulting data would be useless.
148 * Asking for meta-RR types via adns_r_unknown will not work properly
149 * either and may make adns complain about server misbehaviour, so don't
152 * Don't forget adns_qf_quoteok if that's what you want. */
154 adns__qtf_bigaddr
=0x1000000,/* use the new larger sockaddr union */
155 adns__qtf_manyaf
= 0x2000000,/* permitted to return multiple address families */
157 adns__qtf_deref
= adns__qtf_deref_bit
|adns__qtf_bigaddr
158 #ifdef ADNS_FEATURE_MANYAF
161 ,/* dereference domains; perhaps get extra data */
168 adns_r_ns
= adns_r_ns_raw
|adns__qtf_deref
,
173 adns_r_soa
= adns_r_soa_raw
|adns__qtf_mail822
,
175 adns_r_ptr_raw
= 12, /* do not mind PTR with wrong or missing A */
176 adns_r_ptr
= adns_r_ptr_raw
|adns__qtf_deref
,
181 adns_r_mx
= adns_r_mx_raw
|adns__qtf_deref
,
186 adns_r_rp
= adns_r_rp_raw
|adns__qtf_mail822
,
190 /* For SRV records, query domain without _qf_quoteok_query must look
191 * as expected from SRV RFC with hostname-like Name. _With_
192 * _quoteok_query, any query domain is allowed. */
194 adns_r_srv
= adns_r_srv_raw
|adns__qtf_deref
,
196 adns_r_addr
= adns_r_a
|adns__qtf_deref
201 * In queries without qf_quoteok_*, all domains must have standard
202 * legal syntax, or you get adns_s_querydomainvalid (if the query
203 * domain contains bad characters) or adns_s_answerdomaininvalid (if
204 * the answer contains bad characters).
206 * In queries _with_ qf_quoteok_*, domains in the query or response
207 * may contain any characters, quoted according to RFC1035 5.1. On
208 * input to adns, the char* is a pointer to the interior of a "
209 * delimited string, except that " may appear in it unquoted. On
210 * output, the char* is a pointer to a string which would be legal
211 * either inside or outside " delimiters; any character which isn't
212 * legal in a hostname (ie alphanumeric or hyphen) or one of _ / +
213 * (the three other punctuation characters commonly abused in domain
214 * names) will be quoted, as \X if it is a printing ASCII character or
217 * If the query goes via a CNAME then the canonical name (ie, the
218 * thing that the CNAME record refers to) is usually allowed to
219 * contain any characters, which will be quoted as above. With
220 * adns_qf_quotefail_cname you get adns_s_answerdomaininvalid when
221 * this happens. (This is a change from version 0.4 and earlier, in
222 * which failing the query was the default, and you had to say
223 * adns_qf_quoteok_cname to avoid this; that flag is now deprecated.)
225 * In version 0.4 and earlier, asking for _raw records containing
226 * mailboxes without specifying _qf_quoteok_anshost was silly. This
227 * is no longer the case. In this version only parts of responses
228 * that are actually supposed to be hostnames will be refused by
229 * default if quote-requiring characters are found.
233 * If you ask for an RR which contains domains which are actually
234 * encoded mailboxes, and don't ask for the _raw version, then adns
235 * returns the mailbox formatted suitably for an RFC822 recipient
236 * header field. The particular format used is that if the mailbox
237 * requires quoting according to the rules in RFC822 then the
238 * local-part is quoted in double quotes, which end at the next
239 * unescaped double quote (\ is the escape char, and is doubled, and
240 * is used to escape only \ and "). If the local-part is legal
241 * without quoting according to RFC822, it is presented as-is. In any
242 * case the local-part is followed by an @ and the domain. The domain
243 * will not contain any characters not legal in hostnames.
245 * Unquoted local-parts may contain any printing 7-bit ASCII
246 * except the punctuation characters ( ) < > @ , ; : \ " [ ]
247 * I.e. they may contain alphanumerics, and the following
248 * punctuation characters: ! # % ^ & * - _ = + { } .
250 * adns will reject local parts containing control characters (byte
251 * values 0-31, 127-159, and 255) - these appear to be legal according
252 * to RFC822 (at least 0-127) but are clearly a bad idea. RFC1035
253 * syntax does not make any distinction between a single RFC822
254 * quoted-string containing full stops, and a series of quoted-strings
255 * separated by full stops; adns will return anything that isn't all
256 * valid atoms as a single quoted-string. RFC822 does not allow
257 * high-bit-set characters at all, but adns does allow them in
258 * local-parts, treating them as needing quoting.
260 * If you ask for the domain with _raw then _no_ checking is done
261 * (even on the host part, regardless of adns_qf_quoteok_anshost), and
262 * you just get the domain name in master file format.
264 * If no mailbox is supplied the returned string will be `.' in either
271 /* locally induced errors */
273 adns_s_unknownrrtype
,
276 adns_s_max_localfail
= 29,
278 /* remotely induced errors, detected locally */
282 adns_s_invalidresponse
,
283 adns_s_unknownformat
,
285 adns_s_max_remotefail
= 59,
287 /* remotely induced errors, reported by remote server to us */
288 adns_s_rcodeservfail
,
289 adns_s_rcodeformaterror
,
290 adns_s_rcodenotimplemented
,
294 adns_s_max_tempfail
= 99,
296 /* remote configuration errors */
297 adns_s_inconsistent
, /* PTR gives domain whose A does not exist and match */
298 adns_s_prohibitedcname
, /* CNAME, but eg A expected (not if _qf_loosecname) */
299 adns_s_answerdomaininvalid
,
300 adns_s_answerdomaintoolong
,
303 adns_s_max_misconfig
= 199,
305 /* permanent problems with the query */
306 adns_s_querydomainwrong
,
307 adns_s_querydomaininvalid
,
308 adns_s_querydomaintoolong
,
310 adns_s_max_misquery
= 299,
312 /* permanent errors */
316 adns_s_max_permfail
= 499
322 struct sockaddr_in inet
;
323 } adns_sockaddr_v4only
;
327 struct sockaddr_in inet
;
328 struct sockaddr_in6 inet6
;
329 char adns__padding
[240]; /* Good idea? I'm inclined to think not. */
339 adns_sockaddr_v4only addr
;
340 } adns_rr_addr_v4only
;
345 int naddrs
; /* temp fail => -1, perm fail => 0, s_ok => >0 */
356 } adns_rr_inthostaddr
;
359 /* Used both for mx_raw, in which case i is the preference and str
360 * the domain, and for txt, in which case each entry has i for the
361 * `text' length, and str for the data (which will have had an extra
362 * nul appended so that if it was plain text it is now a
363 * null-terminated string).
370 adns_rr_intstr array
[2];
371 } adns_rr_intstrpair
;
375 unsigned long serial
, refresh
, retry
, expire
, minimum
;
379 int priority
, weight
, port
;
384 int priority
, weight
, port
;
395 char *cname
; /* always NULL if query was for CNAME records */
396 char *owner
; /* only set if req'd in query flags; maybe 0 on error anyway */
397 adns_rrtype type
; /* guaranteed to be same as in query */
398 time_t expires
;/*abs time. def only if _s_ok, nxdomain or nodata. NOT TTL!*/
399 int nrrs
, rrsz
; /* nrrs is 0 if an error occurs */
402 unsigned char *bytes
;
403 char *(*str
); /* ns_raw, cname, ptr, ptr_raw */
404 adns_rr_intstr
*(*manyistr
); /* txt (list strs ends with i=-1, str=0)*/
405 adns_rr_addr
*addr
; /* addr */
406 struct in_addr
*inaddr
; /* a */
407 struct in6_addr
*in6addr
; /* aaaa */
408 adns_rr_hostaddr
*hostaddr
; /* ns */
409 adns_rr_intstrpair
*intstrpair
; /* hinfo */
410 adns_rr_strpair
*strpair
; /* rp, rp_raw */
411 adns_rr_inthostaddr
*inthostaddr
;/* mx */
412 adns_rr_intstr
*intstr
; /* mx_raw */
413 adns_rr_soa
*soa
; /* soa, soa_raw */
414 adns_rr_srvraw
*srvraw
; /* srv_raw */
415 adns_rr_srvha
*srvha
;/* srv */
416 adns_rr_byteblock
*byteblock
; /* ...|unknown */
420 /* Memory management:
421 * adns_state and adns_query are actually pointers to malloc'd state;
422 * On submission questions are copied, including the owner domain;
423 * Answers are malloc'd as a single piece of memory; pointers in the
424 * answer struct point into further memory in the answer.
426 * Must always be non-null pointer;
427 * If *query_io is 0 to start with then any query may be returned;
428 * If *query_io is !0 adns_query then only that query may be returned.
429 * If the call is successful, *query_io, *answer_r, and *context_r
432 * Return values are 0 or an errno value.
434 * For _init, _init_strcfg, _submit and _synchronous, system errors
435 * (eg, failure to create sockets, malloc failure, etc.) return errno
436 * values. EINVAL from _init et al means the configuration file
437 * is erroneous and cannot be parsed.
439 * For _wait and _check failures are reported in the answer
440 * structure, and only 0, ESRCH or (for _check) EAGAIN is
441 * returned: if no (appropriate) requests are done adns_check returns
442 * EAGAIN; if no (appropriate) requests are outstanding both
443 * adns_query and adns_wait return ESRCH.
445 * Additionally, _wait can return EINTR if you set adns_if_eintr.
447 * All other errors (nameserver failure, timed out connections, &c)
448 * are returned in the status field of the answer. After a
449 * successful _wait or _check, if status is nonzero then nrrs will be
450 * 0, otherwise it will be >0. type will always be the type
455 * adns does not use any static modifiable state, so it
456 * is safe to call adns_init several times and then use the
457 * resulting adns_states concurrently.
458 * However, it is NOT safe to make simultaneous calls into
459 * adns using the same adns_state; a single adns_state must be used
460 * only by one thread at a time. You can solve this problem by
461 * having one adns_state per thread, or if that isn't feasible, you
462 * could maintain a pool of adns_states. Unfortunately neither of
463 * these approaches has optimal performance.
466 int adns_init(adns_state
*newstate_r
, adns_initflags flags
,
467 FILE *diagfile
/*0=>stderr*/);
469 int adns_init_strcfg(adns_state
*newstate_r
, adns_initflags flags
,
470 FILE *diagfile
/*0=>discard*/, const char *configtext
);
472 typedef void adns_logcallbackfn(adns_state ads
, void *logfndata
,
473 const char *fmt
, va_list al
);
474 /* Will be called perhaps several times for each message; when the
475 * message is complete, the string implied by fmt and al will end in
476 * a newline. Log messages start with `adns debug:' or `adns
477 * warning:' or `adns:' (for errors), or `adns debug [PID]:'
478 * etc. if adns_if_logpid is set. */
480 int adns_init_logfn(adns_state
*newstate_r
, adns_initflags flags
,
481 const char *configtext
/*0=>use default config files*/,
482 adns_logcallbackfn
*logfn
/*0=>logfndata is a FILE* */,
483 void *logfndata
/*0 with logfn==0 => discard*/);
486 * adns_init reads /etc/resolv.conf, which is expected to be (broadly
487 * speaking) in the format expected by libresolv, and then
488 * /etc/resolv-adns.conf if it exists. adns_init_strcfg is instead
489 * passed a string which is interpreted as if it were the contents of
490 * resolv.conf or resolv-adns.conf. In general, configuration which
491 * is set later overrides any that is set earlier.
493 * Standard directives understood in resolv[-adns].conf:
495 * nameserver <address>
496 * Must be followed by the IP address of a nameserver. Several
497 * nameservers may be specified, and they will be tried in the order
498 * found. There is a compiled in limit, currently 5, on the number
499 * of nameservers. (libresolv supports only 3 nameservers.)
501 * search <domain> ...
502 * Specifies the search list for queries which specify
503 * adns_qf_search. This is a list of domains to append to the query
504 * domain. The query domain will be tried as-is either before all
505 * of these or after them, depending on the ndots option setting
509 * This is present only for backward compatibility with obsolete
510 * versions of libresolv. It should not be used, and is interpreted
511 * by adns as if it were `search' - note that this is subtly
512 * different to libresolv's interpretation of this directive.
514 * sortlist <addr>/<mask> ...
515 * Should be followed by a sequence of IP-address and netmask pairs,
516 * separated by spaces. They may be specified as
517 * eg. 172.30.206.0/24 or 172.30.206.0/255.255.255.0. Currently up
518 * to 15 pairs may be specified (but note that libresolv only
519 * supports up to 10).
522 * Should followed by one or more options, separated by spaces.
523 * Each option consists of an option name, followed by optionally
524 * a colon and a value. Options are listed below.
526 * Non-standard directives understood in resolv[-adns].conf:
529 * Clears the list of nameservers, so that further nameserver lines
530 * start again from the beginning.
533 * The specified file will be read.
535 * Additionally, adns will ignore lines in resolv[-adns].conf which
538 * Standard options understood:
541 * Enables debugging output from the resolver, which will be written
545 * Affects whether queries with adns_qf_search will be tried first
546 * without adding domains from the searchlist, or whether the bare
547 * query domain will be tried last. Queries which contain at least
548 * <count> dots will be tried bare first. The default is 1.
550 * Non-standard options understood:
555 * Changes the consistency checking frequency; this overrides the
556 * setting of adns_if_check_entex, adns_if_check_freq, or neither,
557 * in the flags passed to adns_init.
559 * There are a number of environment variables which can modify the
560 * behaviour of adns. They take effect only if adns_init is used, and
561 * the caller of adns_init can disable them using adns_if_noenv. In
562 * each case there is both a FOO and an ADNS_FOO; the latter is
563 * interpreted later so that it can override the former. Unless
564 * otherwise stated, environment variables are interpreted after
565 * resolv[-adns].conf are read, in the order they are listed here.
567 * RES_CONF, ADNS_RES_CONF
568 * A filename, whose contets are in the format of resolv.conf.
570 * RES_CONF_TEXT, ADNS_RES_CONF_TEXT
571 * A string in the format of resolv.conf.
573 * RES_OPTIONS, ADNS_RES_OPTIONS
574 * These are parsed as if they appeared in the `options' line of a
575 * resolv.conf. In addition to being parsed at this point in the
576 * sequence, they are also parsed at the very beginning before
577 * resolv.conf or any other environment variables are read, so that
578 * any debug option can affect the processing of the configuration.
580 * LOCALDOMAIN, ADNS_LOCALDOMAIN
581 * These are interpreted as if their contents appeared in a `search'
582 * line in resolv.conf.
585 int adns_synchronous(adns_state ads
,
588 adns_queryflags flags
,
589 adns_answer
**answer_r
);
591 /* NB: if you set adns_if_noautosys then _submit and _check do not
592 * make any system calls; you must use some of the asynch-io event
593 * processing functions to actually get things to happen.
596 int adns_submit(adns_state ads
,
599 adns_queryflags flags
,
601 adns_query
*query_r
);
603 /* The owner should be quoted in master file format. */
605 int adns_check(adns_state ads
,
606 adns_query
*query_io
,
607 adns_answer
**answer_r
,
610 int adns_wait(adns_state ads
,
611 adns_query
*query_io
,
612 adns_answer
**answer_r
,
615 /* same as adns_wait but uses poll(2) internally */
616 int adns_wait_poll(adns_state ads
,
617 adns_query
*query_io
,
618 adns_answer
**answer_r
,
621 void adns_cancel(adns_query query
);
623 /* The adns_query you get back from _submit is valid (ie, can be
624 * legitimately passed into adns functions) until it is returned by
625 * adns_check or adns_wait, or passed to adns_cancel. After that it
626 * must not be used. You can rely on it not being reused until the
627 * first adns_submit or _transact call using the same adns_state after
628 * it became invalid, so you may compare it for equality with other
629 * query handles until you next call _query or _transact.
631 * _submit and _synchronous return ENOSYS if they don't understand the
635 int adns_submit_reverse(adns_state ads
,
636 const struct sockaddr
*addr
,
638 adns_queryflags flags
,
640 adns_query
*query_r
);
641 /* type must be _r_ptr or _r_ptr_raw. _qf_search is ignored.
642 * addr->sa_family must be AF_INET or you get ENOSYS.
645 int adns_submit_reverse_any(adns_state ads
,
646 const struct sockaddr
*addr
,
649 adns_queryflags flags
,
651 adns_query
*query_r
);
652 /* For RBL-style reverse `zone's; look up
653 * <reversed-address>.<zone>
654 * Any type is allowed. _qf_search is ignored.
655 * addr->sa_family must be AF_INET or you get ENOSYS.
658 void adns_finish(adns_state ads
);
659 /* You may call this even if you have queries outstanding;
660 * they will be cancelled.
664 void adns_forallqueries_begin(adns_state ads
);
665 adns_query
adns_forallqueries_next(adns_state ads
, void **context_r
);
666 /* Iterator functions, which you can use to loop over the outstanding
667 * (submitted but not yet successfuly checked/waited) queries.
669 * You can only have one iteration going at once. You may call _begin
670 * at any time; after that, an iteration will be in progress. You may
671 * only call _next when an iteration is in progress - anything else
672 * may coredump. The iteration remains in progress until _next
673 * returns 0, indicating that all the queries have been walked over,
674 * or ANY other adns function is called with the same adns_state (or a
675 * query in the same adns_state). There is no need to explicitly
676 * finish an iteration.
678 * context_r may be 0. *context_r may not be set when _next returns 0.
681 void adns_checkconsistency(adns_state ads
, adns_query qu
);
682 /* Checks the consistency of adns's internal data structures.
683 * If any error is found, the program will abort().
684 * You may pass 0 for qu; if you pass non-null then additional checks
685 * are done to make sure that qu is a valid query.
689 * Example expected/legal calling sequence for submit/check/wait:
695 * adns_check 3 -> EAGAIN
703 * Entrypoints for generic asynch io:
704 * (these entrypoints are not very useful except in combination with *
705 * some of the other I/O model calls which can tell you which fds to
708 * Note that any adns call may cause adns to open and close fds, so
709 * you must call beforeselect or beforepoll again just before
710 * blocking, or you may not have an up-to-date list of it's fds.
713 int adns_processany(adns_state ads
);
714 /* Gives adns flow-of-control for a bit. This will never block, and
715 * can be used with any threading/asynch-io model. If some error
716 * occurred which might cause an event loop to spin then the errno
720 int adns_processreadable(adns_state ads
, int fd
, const struct timeval
*now
);
721 int adns_processwriteable(adns_state ads
, int fd
, const struct timeval
*now
);
722 int adns_processexceptional(adns_state ads
, int fd
, const struct timeval
*now
);
723 /* Gives adns flow-of-control so that it can process incoming data
724 * from, or send outgoing data via, fd. Very like _processany. If it
725 * returns zero then fd will no longer be readable or writeable
726 * (unless of course more data has arrived since). adns will _only_
727 * use that fd and only in the manner specified, regardless of whether
728 * adns_if_noautosys was specified.
730 * adns_processexceptional should be called when select(2) reports an
731 * exceptional condition, or poll(2) reports POLLPRI.
733 * It is fine to call _processreabable or _processwriteable when the
734 * fd is not ready, or with an fd that doesn't belong to adns; it will
735 * then just return 0.
737 * If some error occurred which might prevent an event loop to spin
738 * then the errno value is returned.
741 void adns_processtimeouts(adns_state ads
, const struct timeval
*now
);
742 /* Gives adns flow-of-control so that it can process any timeouts
743 * which might have happened. Very like _processreadable/writeable.
745 * now may be 0; if it isn't, *now must be the current time, recently
746 * obtained from gettimeofday.
749 void adns_firsttimeout(adns_state ads
,
750 struct timeval
**tv_mod
, struct timeval
*tv_buf
,
752 /* Asks adns when it would first like the opportunity to time
753 * something out. now must be the current time, from gettimeofday.
755 * If tv_mod points to 0 then tv_buf must be non-null, and
756 * _firsttimeout will fill in *tv_buf with the time until the first
757 * timeout, and make *tv_mod point to tv_buf. If adns doesn't have
758 * anything that might need timing out it will leave *tv_mod as 0.
760 * If *tv_mod is not 0 then tv_buf is not used. adns will update
761 * *tv_mod if it has any earlier timeout, and leave it alone if it
764 * This call will not actually do any I/O, or change the fds that adns
765 * is using. It always succeeds and never blocks.
768 void adns_globalsystemfailure(adns_state ads
);
769 /* If serious problem(s) happen which globally affect your ability to
770 * interact properly with adns, or adns's ability to function
771 * properly, you or adns can call this function.
773 * All currently outstanding queries will be made to fail with
774 * adns_s_systemfail, and adns will close any stream sockets it has
777 * This is used by adns, for example, if gettimeofday() fails.
778 * Without this the program's event loop might start to spin !
780 * This call will never block.
784 * Entrypoints for select-loop based asynch io:
787 void adns_beforeselect(adns_state ads
, int *maxfd
, fd_set
*readfds
,
788 fd_set
*writefds
, fd_set
*exceptfds
,
789 struct timeval
**tv_mod
, struct timeval
*tv_buf
,
790 const struct timeval
*now
);
791 /* Find out file descriptors adns is interested in, and when it would
792 * like the opportunity to time something out. If you do not plan to
793 * block then tv_mod may be 0. Otherwise, tv_mod and tv_buf are as
794 * for adns_firsttimeout. readfds, writefds, exceptfds and maxfd_io may
797 * If tv_mod is 0 on entry then this will never actually do any I/O,
798 * or change the fds that adns is using or the timeouts it wants. In
799 * any case it won't block, and it will set the timeout to zero if a
800 * query finishes in _beforeselect.
803 void adns_afterselect(adns_state ads
, int maxfd
, const fd_set
*readfds
,
804 const fd_set
*writefds
, const fd_set
*exceptfds
,
805 const struct timeval
*now
);
806 /* Gives adns flow-of-control for a bit; intended for use after
807 * select. This is just a fancy way of calling adns_processreadable/
808 * writeable/timeouts as appropriate, as if select had returned the
809 * data being passed. Always succeeds.
813 * Example calling sequence:
815 * adns_init _noautosys
821 * adns_submit / adns_check
827 * Entrypoints for poll-loop based asynch io:
831 /* In case your system doesn't have it or you forgot to include
832 * <sys/poll.h>, to stop the following declarations from causing
833 * problems. If your system doesn't have poll then the following
834 * entrypoints will not be defined in libadns. Sorry !
837 int adns_beforepoll(adns_state ads
, struct pollfd
*fds
,
838 int *nfds_io
, int *timeout_io
,
839 const struct timeval
*now
);
840 /* Finds out which fd's adns is interested in, and when it would like
841 * to be able to time things out. This is in a form suitable for use
844 * On entry, usually fds should point to at least *nfds_io structs.
845 * adns will fill up to that many structs will information for poll,
846 * and record in *nfds_io how many structs it filled. If it wants to
847 * listen for more structs then *nfds_io will be set to the number
848 * required and _beforepoll will return ERANGE.
850 * You may call _beforepoll with fds==0 and *nfds_io 0, in which case
851 * adns will fill in the number of fds that it might be interested in
852 * in *nfds_io, and always return either 0 (if it is not interested in
853 * any fds) or ERANGE (if it is).
855 * NOTE that (unless now is 0) adns may acquire additional fds
856 * from one call to the next, so you must put adns_beforepoll in a
857 * loop, rather than assuming that the second call (with the buffer
858 * size requested by the first) will not return ERANGE.
860 * adns only ever sets POLLIN, POLLOUT and POLLPRI in its pollfd
861 * structs, and only ever looks at those bits. POLLPRI is required to
862 * detect TCP Urgent Data (which should not be used by a DNS server)
863 * so that adns can know that the TCP stream is now useless.
865 * In any case, *timeout_io should be a timeout value as for poll(2),
866 * which adns will modify downwards as required. If the caller does
867 * not plan to block then *timeout_io should be 0 on entry, or
868 * alternatively, timeout_io may be 0. (Alternatively, the caller may
869 * use _beforeselect with timeout_io==0 to find out about file
870 * descriptors, and use _firsttimeout is used to find out when adns
871 * might want to time something out.)
873 * adns_beforepoll will return 0 on success, and will not fail for any
874 * reason other than the fds buffer being too small (ERANGE).
876 * This call will never actually do any I/O. If you supply the
877 * current time it will not change the fds that adns is using or the
880 * In any case this call won't block.
883 #define ADNS_POLLFDS_RECOMMENDED 3
884 /* If you allocate an fds buf with at least RECOMMENDED entries then
885 * you are unlikely to need to enlarge it. You are recommended to do
886 * so if it's convenient. However, you must be prepared for adns to
887 * require more space than this.
890 void adns_afterpoll(adns_state ads
, const struct pollfd
*fds
, int nfds
,
891 const struct timeval
*now
);
892 /* Gives adns flow-of-control for a bit; intended for use after
893 * poll(2). fds and nfds should be the results from poll(). pollfd
894 * structs mentioning fds not belonging to adns will be ignored.
898 adns_status
adns_rr_info(adns_rrtype type
,
899 const char **rrtname_r
, const char **fmtname_r
,
901 const void *datap
, char **data_r
);
903 * Get information about a query type, or convert reply data to a
904 * textual form. type must be specified, and the official name of the
905 * corresponding RR type will be returned in *rrtname_r, and
906 * information about the processing style in *fmtname_r. The length
907 * of the table entry in an answer for that type will be returned in
908 * in *len_r. Any or all of rrtname_r, fmtname_r and len_r may be 0.
909 * If fmtname_r is non-null then *fmtname_r may be null on return,
910 * indicating that no special processing is involved.
912 * data_r be must be non-null iff datap is. In this case *data_r will
913 * be set to point to a string pointing to a representation of the RR
914 * data in master file format. (The owner name, timeout, class and
915 * type will not be present - only the data part of the RR.) The
916 * memory will have been obtained from malloc() and must be freed by
919 * Usually this routine will succeed. Possible errors include:
921 * adns_s_rrtypeunknown
922 * adns_s_invaliddata (*datap contained garbage)
923 * If an error occurs then no memory has been allocated,
924 * and *rrtname_r, *fmtname_r, *len_r and *data_r are undefined.
926 * There are some adns-invented data formats which are not official
927 * master file formats. These include:
929 * Mailboxes if __qtf_mail822: these are just included as-is.
931 * Addresses (adns_rr_addr): these may be of pretty much any type.
932 * The representation is in two parts: first, a word for the address
933 * family (ie, in AF_XXX, the XXX), and then one or more items for the
934 * address itself, depending on the format. For an IPv4 address the
935 * syntax is INET followed by the dotted quad (from inet_ntoa).
936 * Currently only IPv4 is supported.
938 * Text strings (as in adns_rr_txt) appear inside double quotes, and
939 * use \" and \\ to represent " and \, and \xHH to represent
940 * characters not in the range 32-126.
942 * Hostname with addresses (adns_rr_hostaddr): this consists of the
943 * hostname, as usual, followed by the adns_status value, as an
944 * abbreviation, and then a descriptive string (encoded as if it were
945 * a piece of text), for the address lookup, followed by zero or more
946 * addresses enclosed in ( and ). If the result was a temporary
947 * failure, then a single ? appears instead of the ( ). If the
948 * result was a permanent failure then an empty pair of parentheses
949 * appears (which a space in between). For example, one of the NS
950 * records for greenend.org.uk comes out like
951 * ns.chiark.greenend.org.uk ok "OK" ( INET 195.224.76.132 )
952 * an MX referring to a nonexistent host might come out like:
953 * 50 sun2.nsfnet-relay.ac.uk nxdomain "No such domain" ( )
954 * and if nameserver information is not available you might get:
955 * dns2.spong.dyn.ml.org timeout "DNS query timed out" ?
958 const char *adns_strerror(adns_status st
);
959 const char *adns_errabbrev(adns_status st
);
960 const char *adns_errtypeabbrev(adns_status st
);
961 /* Like strerror but for adns_status values. adns_errabbrev returns
962 * the abbreviation of the error - eg, for adns_s_timeout it returns
963 * "timeout". adns_errtypeabbrev returns the abbreviation of the
964 * error class: ie, for values up to adns_s_max_XXX it will return the
965 * string XXX. You MUST NOT call these functions with status values
966 * not returned by the same adns library.
970 } /* end of extern "C" */