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 1.19 2007/10/03 20:01:05 nisse 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. */
75 #include "adns-in6fake.h"
78 /* All struct in_addr anywhere in adns are in NETWORK byte order. */
80 typedef struct adns__state *adns_state;
81 typedef struct adns__query *adns_query;
83 typedef enum { /* In general, or together the desired flags: */
84 adns_if_none= 0x0000,/* no flags. nicer than 0 for some compilers */
85 adns_if_noenv= 0x0001,/* do not look at environment */
86 adns_if_noerrprint= 0x0002,/* never print to stderr (_debug overrides) */
87 adns_if_noserverwarn=0x0004,/* do not warn to stderr about duff servers etc */
88 adns_if_debug= 0x0008,/* enable all output to stderr plus debug msgs */
89 adns_if_logpid= 0x0080,/* include pid in diagnostic output */
90 adns_if_noautosys= 0x0010,/* do not make syscalls at every opportunity */
91 adns_if_eintr= 0x0020,/* allow _wait and _synchronous to return EINTR */
92 adns_if_nosigpipe= 0x0040,/* applic has SIGPIPE ignored, do not protect */
93 adns_if_checkc_entex=0x0100,/* consistency checks on entry/exit to adns fns */
94 adns_if_checkc_freq= 0x0300,/* consistency checks very frequently (slow!) */
95 adns_if_ip4only= 0x1000,/* make default be adns_qf_ip4 */
96 adns_if_ip6only= 0x2000,/* make default be adns_qf_ip6 */
97 adns_if_ip6mapped= 0x4000,/* make default be adns_qf_ip4|adns_qf_ip6|adns_qf_ip6mapped */
100 typedef enum { /* In general, or together the desired flags: */
101 adns_qf_none= 0x00000000,/* no flags */
102 adns_qf_search= 0x00000001,/* use the searchlist */
103 adns_qf_usevc= 0x00000002,/* use a virtual circuit (TCP conn) */
104 adns_qf_owner= 0x00000004,/* fill in the owner field in the answer */
105 adns_qf_quoteok_query= 0x00000010,/* allow special chars in query domain */
106 adns_qf_quoteok_cname= 0x00000000,/* ... in CNAME we go via (now default) */
107 adns_qf_quoteok_anshost=0x00000040,/* ... in things supposedly hostnames */
108 adns_qf_quotefail_cname=0x00000080,/* refuse if quote-req chars in CNAME we go via */
109 adns_qf_cname_loose= 0x00000100,/* allow refs to CNAMEs - without, get _s_cname */
110 adns_qf_cname_forbid= 0x00000200,/* don't follow CNAMEs, instead give _s_cname */
112 /* Affects addr queries and additional section processing */
113 adns_qf_ip4= 0x00001000, /* Ask for A records */
114 adns_qf_ip6= 0x00002000, /* Ask for AAAA records */
115 adns_qf_ip6mapped= 0x00004000, /* Return any IPv4 addresses as IPv6 mapped addresses */
117 adns__qf_ip_mask= 0x00003000,
118 adns__qf_internalmask= 0x0ff00000
123 * The _qf_ip4 and _qf_ip6 says which kinds of address records (A and
124 * AAAA) we should ask for. _qf_ip6mapped says how we return ipv6
125 * addresses to the caller. Four modes of operation, corresponding to
128 * Record type: A AAAA
131 * Default => AF_INET => AF_INET6
133 * _if_ip4only => AF_INET not used
135 * _if_ip6only not used => AF_INET6
137 * _if_ipv6mapped => AF_INET6 => AF_INET6
139 * _if_ip4only => AF_INET6 not used
142 * Furthermore, there are configuration options which can prevent the
143 * use of either AAAA or A records for _r_addr; so it is safe to use
144 * _qf_ip6_mapped and _r_addr without checking explicitly whether the host
145 * has IPv6 connectivity.
147 * The corresponding _qf_ip* flags are constructed from the _if_ip*
148 * flags and the query flags submitted to functions like adns_submit.
149 * If none of _qf_ip4 and _qf_ip6 are set explicitly in the query
150 * flags, the default behaviour is used. If the flags are set, the
151 * default configuration is overridden.
153 * Applications which do not support IPv4 should set none of these
154 * flags. Applications which have been `naively' converted to use
155 * AF_INET6 throughout should set adns_if_ip6. Applications which
156 * know what they are doing should know which flags to set :-).
160 adns_rrt_typemask= 0x0ffff,
161 adns__qtf_deref= 0x10000,/* dereference domains; perhaps get extra data */
162 adns__qtf_mail822= 0x20000,/* return mailboxes in RFC822 rcpt field fmt */
164 adns_r_unknown= 0x40000,
165 /* To use this, ask for records of type <rr-type-code>|adns_r_unknown.
166 * adns will not process the RDATA - you'll get adns_rr_byteblocks,
167 * where the int is the length and the unsigned char* points to the
168 * data. String representation of the RR data (by adns_rrinfo) is as in
169 * RFC3597. adns_rr_info will not return the type name in *rrtname_r
170 * (due to memory management problems); *fmtname_r will be set to
173 * Do not specify adns_r_unknown along with a known RR type which
174 * requires domain name uncompression (see RFC3597 s4); domain names
175 * will not be uncompressed and the resulting data would be useless.
176 * Asking for meta-RR types via adns_r_unknown will not work properly
177 * either and may make adns complain about server misbehaviour, so don't
180 * Don't forget adns_qf_quoteok if that's what you want. */
182 adns__qtf_special= 0x80000,/* no simple correspondence to a single rr type */
189 adns_r_ns= adns_r_ns_raw|adns__qtf_deref,
194 adns_r_soa= adns_r_soa_raw|adns__qtf_mail822,
196 adns_r_ptr_raw= 12, /* do not mind PTR with wrong or missing A */
197 adns_r_ptr= adns_r_ptr_raw|adns__qtf_deref,
202 adns_r_mx= adns_r_mx_raw|adns__qtf_deref,
207 adns_r_rp= adns_r_rp_raw|adns__qtf_mail822,
208 adns_r_aaaa= 28, /* RFC 1886 */
210 /* For SRV records, query domain without _qf_quoteok_query must look
211 * as expected from SRV RFC with hostname-like Name. _With_
212 * _quoteok_query, any query domain is allowed. */
214 adns_r_srv= adns_r_srv_raw|adns__qtf_deref,
216 /* FIXME: Maybe add adns__qtf_deref too? */
217 adns_r_addr= 1 | adns__qtf_special,
222 * In queries without qf_quoteok_*, all domains must have standard
223 * legal syntax, or you get adns_s_querydomainvalid (if the query
224 * domain contains bad characters) or adns_s_answerdomaininvalid (if
225 * the answer contains bad characters).
227 * In queries _with_ qf_quoteok_*, domains in the query or response
228 * may contain any characters, quoted according to RFC1035 5.1. On
229 * input to adns, the char* is a pointer to the interior of a "
230 * delimited string, except that " may appear in it unquoted. On
231 * output, the char* is a pointer to a string which would be legal
232 * either inside or outside " delimiters; any character which isn't
233 * legal in a hostname (ie alphanumeric or hyphen) or one of _ / +
234 * (the three other punctuation characters commonly abused in domain
235 * names) will be quoted, as \X if it is a printing ASCII character or
238 * If the query goes via a CNAME then the canonical name (ie, the
239 * thing that the CNAME record refers to) is usually allowed to
240 * contain any characters, which will be quoted as above. With
241 * adns_qf_quotefail_cname you get adns_s_answerdomaininvalid when
242 * this happens. (This is a change from version 0.4 and earlier, in
243 * which failing the query was the default, and you had to say
244 * adns_qf_quoteok_cname to avoid this; that flag is now deprecated.)
246 * In version 0.4 and earlier, asking for _raw records containing
247 * mailboxes without specifying _qf_quoteok_anshost was silly. This
248 * is no longer the case. In this version only parts of responses
249 * that are actually supposed to be hostnames will be refused by
250 * default if quote-requiring characters are found.
254 * If you ask for an RR which contains domains which are actually
255 * encoded mailboxes, and don't ask for the _raw version, then adns
256 * returns the mailbox formatted suitably for an RFC822 recipient
257 * header field. The particular format used is that if the mailbox
258 * requires quoting according to the rules in RFC822 then the
259 * local-part is quoted in double quotes, which end at the next
260 * unescaped double quote (\ is the escape char, and is doubled, and
261 * is used to escape only \ and "). If the local-part is legal
262 * without quoting according to RFC822, it is presented as-is. In any
263 * case the local-part is followed by an @ and the domain. The domain
264 * will not contain any characters not legal in hostnames.
266 * Unquoted local-parts may contain any printing 7-bit ASCII
267 * except the punctuation characters ( ) < > @ , ; : \ " [ ]
268 * I.e. they may contain alphanumerics, and the following
269 * punctuation characters: ! # % ^ & * - _ = + { } .
271 * adns will reject local parts containing control characters (byte
272 * values 0-31, 127-159, and 255) - these appear to be legal according
273 * to RFC822 (at least 0-127) but are clearly a bad idea. RFC1035
274 * syntax does not make any distinction between a single RFC822
275 * quoted-string containing full stops, and a series of quoted-strings
276 * separated by full stops; adns will return anything that isn't all
277 * valid atoms as a single quoted-string. RFC822 does not allow
278 * high-bit-set characters at all, but adns does allow them in
279 * local-parts, treating them as needing quoting.
281 * If you ask for the domain with _raw then _no_ checking is done
282 * (even on the host part, regardless of adns_qf_quoteok_anshost), and
283 * you just get the domain name in master file format.
285 * If no mailbox is supplied the returned string will be `.' in either
292 /* locally induced errors */
294 adns_s_unknownrrtype,
297 adns_s_max_localfail= 29,
299 /* remotely induced errors, detected locally */
303 adns_s_invalidresponse,
304 adns_s_unknownformat,
306 adns_s_max_remotefail= 59,
308 /* remotely induced errors, reported by remote server to us */
309 adns_s_rcodeservfail,
310 adns_s_rcodeformaterror,
311 adns_s_rcodenotimplemented,
315 adns_s_max_tempfail= 99,
317 /* remote configuration errors */
318 adns_s_inconsistent, /* PTR gives domain whose A does not exist and match */
319 adns_s_prohibitedcname, /* CNAME, but eg A expected (not if _qf_loosecname) */
320 adns_s_answerdomaininvalid,
321 adns_s_answerdomaintoolong,
324 adns_s_max_misconfig= 199,
326 /* permanent problems with the query */
327 adns_s_querydomainwrong,
328 adns_s_querydomaininvalid,
329 adns_s_querydomaintoolong,
331 adns_s_max_misquery= 299,
333 /* permanent errors */
337 adns_s_max_permfail= 499
344 int order; /* Cache index on sortlist? */
348 struct sockaddr_in inet;
349 struct sockaddr_in6 inet6;
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.
572 * Return only IPv6, respectively only IPv4 addresses, in
573 * _rr_addr's. This may result in an adns_s_nodata error, if the
574 * application only supports, or the remote host only has, the wrong
577 * There are a number of environment variables which can modify the
578 * behaviour of adns. They take effect only if adns_init is used, and
579 * the caller of adns_init can disable them using adns_if_noenv. In
580 * each case there is both a FOO and an ADNS_FOO; the latter is
581 * interpreted later so that it can override the former. Unless
582 * otherwise stated, environment variables are interpreted after
583 * resolv[-adns].conf are read, in the order they are listed here.
585 * RES_CONF, ADNS_RES_CONF
586 * A filename, whose contets are in the format of resolv.conf.
588 * RES_CONF_TEXT, ADNS_RES_CONF_TEXT
589 * A string in the format of resolv.conf.
591 * RES_OPTIONS, ADNS_RES_OPTIONS
592 * These are parsed as if they appeared in the `options' line of a
593 * resolv.conf. In addition to being parsed at this point in the
594 * sequence, they are also parsed at the very beginning before
595 * resolv.conf or any other environment variables are read, so that
596 * any debug option can affect the processing of the configuration.
598 * LOCALDOMAIN, ADNS_LOCALDOMAIN
599 * These are interpreted as if their contents appeared in a `search'
600 * line in resolv.conf.
603 int adns_synchronous(adns_state ads,
606 adns_queryflags flags,
607 adns_answer **answer_r);
609 /* NB: if you set adns_if_noautosys then _submit and _check do not
610 * make any system calls; you must use some of the asynch-io event
611 * processing functions to actually get things to happen.
614 int adns_submit(adns_state ads,
617 adns_queryflags flags,
619 adns_query *query_r);
621 /* The owner should be quoted in master file format. */
623 int adns_check(adns_state ads,
624 adns_query *query_io,
625 adns_answer **answer_r,
628 int adns_wait(adns_state ads,
629 adns_query *query_io,
630 adns_answer **answer_r,
633 /* same as adns_wait but uses poll(2) internally */
634 int adns_wait_poll(adns_state ads,
635 adns_query *query_io,
636 adns_answer **answer_r,
639 void adns_cancel(adns_query query);
641 /* The adns_query you get back from _submit is valid (ie, can be
642 * legitimately passed into adns functions) until it is returned by
643 * adns_check or adns_wait, or passed to adns_cancel. After that it
644 * must not be used. You can rely on it not being reused until the
645 * first adns_submit or _transact call using the same adns_state after
646 * it became invalid, so you may compare it for equality with other
647 * query handles until you next call _query or _transact.
649 * _submit and _synchronous return ENOSYS if they don't understand the
653 int adns_submit_reverse(adns_state ads,
654 const struct sockaddr *addr,
656 adns_queryflags flags,
658 adns_query *query_r);
659 /* type must be _r_ptr or _r_ptr_raw. _qf_search is ignored.
660 * addr->sa_family must be AF_INET or AF_INET6 or you get ENOSYS.
663 int adns_getaddrinfo(adns_state ads,
664 const char *name, /* Eg, "www.example.coom" */
665 const char *service, /* Eg, "http" */
666 const char *protocol, /* Eg, "tcp" */
667 unsigned short defaultport, /* Eg, 80 */
668 adns_queryflags flags,
669 adns_answer **answer_r, int *invented_r);
670 /* Does an SRV lookup (RFC2052). If this fails, tries an AAAA or A
671 * lookup instead, and if found uses getservbyname to find the port
672 * number (or failing that, uses defaultport. The defaultport is in
673 * hot byte order). In the `fallback' case, will invent an SRV record
674 * which have priority and weight == 0 and set *invented_r to 1; if
675 * real SRV records were found, will set *invented_r to 0. invented_r
676 * may be null but answer_r may not be. If _getaddrinfo returns
677 * nonzero, *answer_r and/or *invented_r may or may not have been
678 * overwritten and should not be used.
680 * NB, like adns_synchronous, can fail either by returning an errno
681 * value, or by returning an adns_answer with ->nrrs==0 and
684 * You have to write two loops when using the returned value, an outer
685 * one to loop over the returned SRV's, and an inner one to loop over
686 * the addresses for each one.
689 int adns_submit_reverse_any(adns_state ads,
690 const struct sockaddr *addr,
693 adns_queryflags flags,
695 adns_query *query_r);
696 /* For RBL-style reverse `zone's; look up
697 * <reversed-address>.<zone>
698 * Any type is allowed. _qf_search is ignored.
699 * addr->sa_family must be AF_INET or AF_INET6 or you get ENOSYS.
702 void adns_finish(adns_state ads);
703 /* You may call this even if you have queries outstanding;
704 * they will be cancelled.
708 void adns_forallqueries_begin(adns_state ads);
709 adns_query adns_forallqueries_next(adns_state ads, void **context_r);
710 /* Iterator functions, which you can use to loop over the outstanding
711 * (submitted but not yet successfuly checked/waited) queries.
713 * You can only have one iteration going at once. You may call _begin
714 * at any time; after that, an iteration will be in progress. You may
715 * only call _next when an iteration is in progress - anything else
716 * may coredump. The iteration remains in progress until _next
717 * returns 0, indicating that all the queries have been walked over,
718 * or ANY other adns function is called with the same adns_state (or a
719 * query in the same adns_state). There is no need to explicitly
720 * finish an iteration.
722 * context_r may be 0. *context_r may not be set when _next returns 0.
725 void adns_checkconsistency(adns_state ads, adns_query qu);
726 /* Checks the consistency of adns's internal data structures.
727 * If any error is found, the program will abort().
728 * You may pass 0 for qu; if you pass non-null then additional checks
729 * are done to make sure that qu is a valid query.
733 * Example expected/legal calling sequence for submit/check/wait:
739 * adns_check 3 -> EAGAIN
747 * Entrypoints for generic asynch io:
748 * (these entrypoints are not very useful except in combination with *
749 * some of the other I/O model calls which can tell you which fds to
752 * Note that any adns call may cause adns to open and close fds, so
753 * you must call beforeselect or beforepoll again just before
754 * blocking, or you may not have an up-to-date list of it's fds.
757 int adns_processany(adns_state ads);
758 /* Gives adns flow-of-control for a bit. This will never block, and
759 * can be used with any threading/asynch-io model. If some error
760 * occurred which might cause an event loop to spin then the errno
764 int adns_processreadable(adns_state ads, int fd, const struct timeval *now);
765 int adns_processwriteable(adns_state ads, int fd, const struct timeval *now);
766 int adns_processexceptional(adns_state ads, int fd, const struct timeval *now);
767 /* Gives adns flow-of-control so that it can process incoming data
768 * from, or send outgoing data via, fd. Very like _processany. If it
769 * returns zero then fd will no longer be readable or writeable
770 * (unless of course more data has arrived since). adns will _only_
771 * use that fd and only in the manner specified, regardless of whether
772 * adns_if_noautosys was specified.
774 * adns_processexceptional should be called when select(2) reports an
775 * exceptional condition, or poll(2) reports POLLPRI.
777 * It is fine to call _processreabable or _processwriteable when the
778 * fd is not ready, or with an fd that doesn't belong to adns; it will
779 * then just return 0.
781 * If some error occurred which might prevent an event loop to spin
782 * then the errno value is returned.
785 void adns_processtimeouts(adns_state ads, const struct timeval *now);
786 /* Gives adns flow-of-control so that it can process any timeouts
787 * which might have happened. Very like _processreadable/writeable.
789 * now may be 0; if it isn't, *now must be the current time, recently
790 * obtained from gettimeofday.
793 void adns_firsttimeout(adns_state ads,
794 struct timeval **tv_mod, struct timeval *tv_buf,
796 /* Asks adns when it would first like the opportunity to time
797 * something out. now must be the current time, from gettimeofday.
799 * If tv_mod points to 0 then tv_buf must be non-null, and
800 * _firsttimeout will fill in *tv_buf with the time until the first
801 * timeout, and make *tv_mod point to tv_buf. If adns doesn't have
802 * anything that might need timing out it will leave *tv_mod as 0.
804 * If *tv_mod is not 0 then tv_buf is not used. adns will update
805 * *tv_mod if it has any earlier timeout, and leave it alone if it
808 * This call will not actually do any I/O, or change the fds that adns
809 * is using. It always succeeds and never blocks.
812 void adns_globalsystemfailure(adns_state ads);
813 /* If serious problem(s) happen which globally affect your ability to
814 * interact properly with adns, or adns's ability to function
815 * properly, you or adns can call this function.
817 * All currently outstanding queries will be made to fail with
818 * adns_s_systemfail, and adns will close any stream sockets it has
821 * This is used by adns, for example, if gettimeofday() fails.
822 * Without this the program's event loop might start to spin !
824 * This call will never block.
828 * Entrypoints for select-loop based asynch io:
831 void adns_beforeselect(adns_state ads, int *maxfd, fd_set *readfds,
832 fd_set *writefds, fd_set *exceptfds,
833 struct timeval **tv_mod, struct timeval *tv_buf,
834 const struct timeval *now);
835 /* Find out file descriptors adns is interested in, and when it would
836 * like the opportunity to time something out. If you do not plan to
837 * block then tv_mod may be 0. Otherwise, tv_mod and tv_buf are as
838 * for adns_firsttimeout. readfds, writefds, exceptfds and maxfd_io may
841 * If tv_mod is 0 on entry then this will never actually do any I/O,
842 * or change the fds that adns is using or the timeouts it wants. In
843 * any case it won't block, and it will set the timeout to zero if a
844 * query finishes in _beforeselect.
847 void adns_afterselect(adns_state ads, int maxfd, const fd_set *readfds,
848 const fd_set *writefds, const fd_set *exceptfds,
849 const struct timeval *now);
850 /* Gives adns flow-of-control for a bit; intended for use after
851 * select. This is just a fancy way of calling adns_processreadable/
852 * writeable/timeouts as appropriate, as if select had returned the
853 * data being passed. Always succeeds.
857 * Example calling sequence:
859 * adns_init _noautosys
865 * adns_submit / adns_check
871 * Entrypoints for poll-loop based asynch io:
875 /* In case your system doesn't have it or you forgot to include
876 * <sys/poll.h>, to stop the following declarations from causing
877 * problems. If your system doesn't have poll then the following
878 * entrypoints will not be defined in libadns. Sorry !
881 int adns_beforepoll(adns_state ads, struct pollfd *fds,
882 int *nfds_io, int *timeout_io,
883 const struct timeval *now);
884 /* Finds out which fd's adns is interested in, and when it would like
885 * to be able to time things out. This is in a form suitable for use
888 * On entry, usually fds should point to at least *nfds_io structs.
889 * adns will fill up to that many structs will information for poll,
890 * and record in *nfds_io how many structs it filled. If it wants to
891 * listen for more structs then *nfds_io will be set to the number
892 * required and _beforepoll will return ERANGE.
894 * You may call _beforepoll with fds==0 and *nfds_io 0, in which case
895 * adns will fill in the number of fds that it might be interested in
896 * in *nfds_io, and always return either 0 (if it is not interested in
897 * any fds) or ERANGE (if it is).
899 * NOTE that (unless now is 0) adns may acquire additional fds
900 * from one call to the next, so you must put adns_beforepoll in a
901 * loop, rather than assuming that the second call (with the buffer
902 * size requested by the first) will not return ERANGE.
904 * adns only ever sets POLLIN, POLLOUT and POLLPRI in its pollfd
905 * structs, and only ever looks at those bits. POLLPRI is required to
906 * detect TCP Urgent Data (which should not be used by a DNS server)
907 * so that adns can know that the TCP stream is now useless.
909 * In any case, *timeout_io should be a timeout value as for poll(2),
910 * which adns will modify downwards as required. If the caller does
911 * not plan to block then *timeout_io should be 0 on entry, or
912 * alternatively, timeout_io may be 0. (Alternatively, the caller may
913 * use _beforeselect with timeout_io==0 to find out about file
914 * descriptors, and use _firsttimeout is used to find out when adns
915 * might want to time something out.)
917 * adns_beforepoll will return 0 on success, and will not fail for any
918 * reason other than the fds buffer being too small (ERANGE).
920 * This call will never actually do any I/O. If you supply the
921 * current time it will not change the fds that adns is using or the
924 * In any case this call won't block.
927 #define ADNS_POLLFDS_RECOMMENDED 2
928 /* If you allocate an fds buf with at least RECOMMENDED entries then
929 * you are unlikely to need to enlarge it. You are recommended to do
930 * so if it's convenient. However, you must be prepared for adns to
931 * require more space than this.
934 void adns_afterpoll(adns_state ads, const struct pollfd *fds, int nfds,
935 const struct timeval *now);
936 /* Gives adns flow-of-control for a bit; intended for use after
937 * poll(2). fds and nfds should be the results from poll(). pollfd
938 * structs mentioning fds not belonging to adns will be ignored.
942 adns_status adns_rr_info(adns_rrtype type,
943 const char **rrtname_r, const char **fmtname_r,
945 const void *datap, char **data_r);
947 * Get information about a query type, or convert reply data to a
948 * textual form. type must be specified, and the official name of the
949 * corresponding RR type will be returned in *rrtname_r, and
950 * information about the processing style in *fmtname_r. The length
951 * of the table entry in an answer for that type will be returned in
952 * in *len_r. Any or all of rrtname_r, fmtname_r and len_r may be 0.
953 * If fmtname_r is non-null then *fmtname_r may be null on return,
954 * indicating that no special processing is involved.
956 * data_r be must be non-null iff datap is. In this case *data_r will
957 * be set to point to a string pointing to a representation of the RR
958 * data in master file format. (The owner name, timeout, class and
959 * type will not be present - only the data part of the RR.) The
960 * memory will have been obtained from malloc() and must be freed by
963 * Usually this routine will succeed. Possible errors include:
965 * adns_s_rrtypeunknown
966 * adns_s_invaliddata (*datap contained garbage)
967 * If an error occurs then no memory has been allocated,
968 * and *rrtname_r, *fmtname_r, *len_r and *data_r are undefined.
970 * There are some adns-invented data formats which are not official
971 * master file formats. These include:
973 * Mailboxes if __qtf_mail822: these are just included as-is.
975 * Addresses (adns_rr_addr): these may be of pretty much any type.
976 * The representation is in two parts: first, a word for the address
977 * family (ie, in AF_XXX, the XXX), and then one or more items for the
978 * address itself, depending on the format. For an IPv4 address the
979 * syntax is INET followed by the dotted quad (from inet_ntoa).
980 * Currently only IPv4 is supported.
982 * Text strings (as in adns_rr_txt) appear inside double quotes, and
983 * use \" and \\ to represent " and \, and \xHH to represent
984 * characters not in the range 32-126.
986 * Hostname with addresses (adns_rr_hostaddr): this consists of the
987 * hostname, as usual, followed by the adns_status value, as an
988 * abbreviation, and then a descriptive string (encoded as if it were
989 * a piece of text), for the address lookup, followed by zero or more
990 * addresses enclosed in ( and ). If the result was a temporary
991 * failure, then a single ? appears instead of the ( ). If the
992 * result was a permanent failure then an empty pair of parentheses
993 * appears (which a space in between). For example, one of the NS
994 * records for greenend.org.uk comes out like
995 * ns.chiark.greenend.org.uk ok "OK" ( INET 195.224.76.132 )
996 * an MX referring to a nonexistent host might come out like:
997 * 50 sun2.nsfnet-relay.ac.uk nxdomain "No such domain" ( )
998 * and if nameserver information is not available you might get:
999 * dns2.spong.dyn.ml.org timeout "DNS query timed out" ?
1002 const char *adns_strerror(adns_status st);
1003 const char *adns_errabbrev(adns_status st);
1004 const char *adns_errtypeabbrev(adns_status st);
1005 /* Like strerror but for adns_status values. adns_errabbrev returns
1006 * the abbreviation of the error - eg, for adns_s_timeout it returns
1007 * "timeout". adns_errtypeabbrev returns the abbreviation of the
1008 * error class: ie, for values up to adns_s_max_XXX it will return the
1009 * string XXX. You MUST NOT call these functions with status values
1010 * not returned by the same adns library.
1014 } /* end of extern "C" */