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dns.h
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1 /*
2  * Copyright (c) 2006-2007 Niels Provos <provos@citi.umich.edu>
3  * Copyright (c) 2007-2012 Niels Provos and Nick Mathewson
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  * notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  * notice, this list of conditions and the following disclaimer in the
12  * documentation and/or other materials provided with the distribution.
13  * 3. The name of the author may not be used to endorse or promote products
14  * derived from this software without specific prior written permission.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26  */
27 
28 /*
29  * The original DNS code is due to Adam Langley with heavy
30  * modifications by Nick Mathewson. Adam put his DNS software in the
31  * public domain. You can find his original copyright below. Please,
32  * aware that the code as part of Libevent is governed by the 3-clause
33  * BSD license above.
34  *
35  * This software is Public Domain. To view a copy of the public domain dedication,
36  * visit http://creativecommons.org/licenses/publicdomain/ or send a letter to
37  * Creative Commons, 559 Nathan Abbott Way, Stanford, California 94305, USA.
38  *
39  * I ask and expect, but do not require, that all derivative works contain an
40  * attribution similar to:
41  * Parts developed by Adam Langley <agl@imperialviolet.org>
42  *
43  * You may wish to replace the word "Parts" with something else depending on
44  * the amount of original code.
45  *
46  * (Derivative works does not include programs which link against, run or include
47  * the source verbatim in their source distributions)
48  */
49 
135 #ifndef EVENT2_DNS_H_INCLUDED_
136 #define EVENT2_DNS_H_INCLUDED_
137 
138 #include <event2/visibility.h>
139 
140 #ifdef __cplusplus
141 extern "C" {
142 #endif
143 
144 /* For integer types. */
145 #include <event2/util.h>
146 
148 #define DNS_ERR_NONE 0
149 
150 #define DNS_ERR_FORMAT 1
151 
153 #define DNS_ERR_SERVERFAILED 2
154 
155 #define DNS_ERR_NOTEXIST 3
156 
157 #define DNS_ERR_NOTIMPL 4
158 
160 #define DNS_ERR_REFUSED 5
161 
162 #define DNS_ERR_TRUNCATED 65
163 
164 #define DNS_ERR_UNKNOWN 66
165 
166 #define DNS_ERR_TIMEOUT 67
167 
168 #define DNS_ERR_SHUTDOWN 68
169 
170 #define DNS_ERR_CANCEL 69
171 
174 #define DNS_ERR_NODATA 70
175 
176 #define DNS_IPv4_A 1
177 #define DNS_PTR 2
178 #define DNS_IPv6_AAAA 3
179 
180 #define DNS_QUERY_NO_SEARCH 1
181 
182 /* Allow searching */
183 #define DNS_OPTION_SEARCH 1
184 /* Parse "nameserver" and add default if no such section */
185 #define DNS_OPTION_NAMESERVERS 2
186 /* Parse additional options like:
187  * - timeout:
188  * - getaddrinfo-allow-skew:
189  * - max-timeouts:
190  * - max-inflight:
191  * - attempts:
192  * - randomize-case:
193  * - initial-probe-timeout:
194  */
195 #define DNS_OPTION_MISC 4
196 /* Load hosts file (i.e. "/etc/hosts") */
197 #define DNS_OPTION_HOSTSFILE 8
198 
205 #define DNS_OPTIONS_ALL ( \
206  DNS_OPTION_SEARCH | \
207  DNS_OPTION_NAMESERVERS | \
208  DNS_OPTION_MISC | \
209  DNS_OPTION_HOSTSFILE | \
210  0 \
211 )
212 /* Do not "default" nameserver (i.e. "127.0.0.1:53") if there is no nameservers
213  * in resolv.conf, (iff DNS_OPTION_NAMESERVERS is set) */
214 #define DNS_OPTION_NAMESERVERS_NO_DEFAULT 16
215 
216 /* Obsolete name for DNS_QUERY_NO_SEARCH */
217 #define DNS_NO_SEARCH DNS_QUERY_NO_SEARCH
218 
229 typedef void (*evdns_callback_type) (int result, char type, int count, int ttl, void *addresses, void *arg);
230 
231 struct evdns_base;
232 struct event_base;
233 
235 #define EVDNS_BASE_INITIALIZE_NAMESERVERS 1
236 
238 #define EVDNS_BASE_DISABLE_WHEN_INACTIVE 0x8000
239 
242 #define EVDNS_BASE_NAMESERVERS_NO_DEFAULT 0x10000
243 
257 EVENT2_EXPORT_SYMBOL
258 struct evdns_base * evdns_base_new(struct event_base *event_base, int initialize_nameservers);
259 
260 
273 EVENT2_EXPORT_SYMBOL
274 void evdns_base_free(struct evdns_base *base, int fail_requests);
275 
282 EVENT2_EXPORT_SYMBOL
283 void evdns_base_clear_host_addresses(struct evdns_base *base);
284 
291 EVENT2_EXPORT_SYMBOL
292 const char *evdns_err_to_string(int err);
293 
294 
306 EVENT2_EXPORT_SYMBOL
307 int evdns_base_nameserver_add(struct evdns_base *base,
308  unsigned long int address);
309 
322 EVENT2_EXPORT_SYMBOL
323 int evdns_base_count_nameservers(struct evdns_base *base);
324 
334 EVENT2_EXPORT_SYMBOL
335 int evdns_base_clear_nameservers_and_suspend(struct evdns_base *base);
336 
337 
348 EVENT2_EXPORT_SYMBOL
349 int evdns_base_resume(struct evdns_base *base);
350 
368 EVENT2_EXPORT_SYMBOL
369 int evdns_base_nameserver_ip_add(struct evdns_base *base,
370  const char *ip_as_string);
371 
375 EVENT2_EXPORT_SYMBOL
376 int
377 evdns_base_nameserver_sockaddr_add(struct evdns_base *base,
378  const struct sockaddr *sa, ev_socklen_t len, unsigned flags);
379 
380 struct evdns_request;
381 
393 EVENT2_EXPORT_SYMBOL
394 struct evdns_request *evdns_base_resolve_ipv4(struct evdns_base *base, const char *name, int flags, evdns_callback_type callback, void *ptr);
395 
407 EVENT2_EXPORT_SYMBOL
408 struct evdns_request *evdns_base_resolve_ipv6(struct evdns_base *base, const char *name, int flags, evdns_callback_type callback, void *ptr);
409 
410 struct in_addr;
411 struct in6_addr;
412 
424 EVENT2_EXPORT_SYMBOL
425 struct evdns_request *evdns_base_resolve_reverse(struct evdns_base *base, const struct in_addr *in, int flags, evdns_callback_type callback, void *ptr);
426 
427 
439 EVENT2_EXPORT_SYMBOL
440 struct evdns_request *evdns_base_resolve_reverse_ipv6(struct evdns_base *base, const struct in6_addr *in, int flags, evdns_callback_type callback, void *ptr);
441 
449 EVENT2_EXPORT_SYMBOL
450 void evdns_cancel_request(struct evdns_base *base, struct evdns_request *req);
451 
469 EVENT2_EXPORT_SYMBOL
470 int evdns_base_set_option(struct evdns_base *base, const char *option, const char *val);
471 
472 
495 EVENT2_EXPORT_SYMBOL
496 int evdns_base_resolv_conf_parse(struct evdns_base *base, int flags, const char *const filename);
497 
511 EVENT2_EXPORT_SYMBOL
512 int evdns_base_load_hosts(struct evdns_base *base, const char *hosts_fname);
513 
514 #if defined(EVENT_IN_DOXYGEN_) || defined(_WIN32)
515 
525 EVENT2_EXPORT_SYMBOL
526 int evdns_base_config_windows_nameservers(struct evdns_base *);
527 #define EVDNS_BASE_CONFIG_WINDOWS_NAMESERVERS_IMPLEMENTED
528 #endif
529 
530 
534 EVENT2_EXPORT_SYMBOL
535 void evdns_base_search_clear(struct evdns_base *base);
536 
537 
543 EVENT2_EXPORT_SYMBOL
544 void evdns_base_search_add(struct evdns_base *base, const char *domain);
545 
546 
555 EVENT2_EXPORT_SYMBOL
556 void evdns_base_search_ndots_set(struct evdns_base *base, const int ndots);
557 
564 typedef void (*evdns_debug_log_fn_type)(int is_warning, const char *msg);
565 
566 
574 EVENT2_EXPORT_SYMBOL
576 
587 EVENT2_EXPORT_SYMBOL
588 void evdns_set_transaction_id_fn(ev_uint16_t (*fn)(void));
589 
599 EVENT2_EXPORT_SYMBOL
600 void evdns_set_random_bytes_fn(void (*fn)(char *, size_t));
601 
602 /*
603  * Functions used to implement a DNS server.
604  */
605 
606 struct evdns_server_request;
607 struct evdns_server_question;
608 
620 typedef void (*evdns_request_callback_fn_type)(struct evdns_server_request *, void *);
621 #define EVDNS_ANSWER_SECTION 0
622 #define EVDNS_AUTHORITY_SECTION 1
623 #define EVDNS_ADDITIONAL_SECTION 2
624 
625 #define EVDNS_TYPE_A 1
626 #define EVDNS_TYPE_NS 2
627 #define EVDNS_TYPE_CNAME 5
628 #define EVDNS_TYPE_SOA 6
629 #define EVDNS_TYPE_PTR 12
630 #define EVDNS_TYPE_MX 15
631 #define EVDNS_TYPE_TXT 16
632 #define EVDNS_TYPE_AAAA 28
633 
634 #define EVDNS_QTYPE_AXFR 252
635 #define EVDNS_QTYPE_ALL 255
636 
637 #define EVDNS_CLASS_INET 1
638 
639 /* flags that can be set in answers; as part of the err parameter */
640 #define EVDNS_FLAGS_AA 0x400
641 #define EVDNS_FLAGS_RD 0x080
642 
654 EVENT2_EXPORT_SYMBOL
655 struct evdns_server_port *evdns_add_server_port_with_base(struct event_base *base, evutil_socket_t socket, int flags, evdns_request_callback_fn_type callback, void *user_data);
657 EVENT2_EXPORT_SYMBOL
658 void evdns_close_server_port(struct evdns_server_port *port);
659 
663 EVENT2_EXPORT_SYMBOL
664 void evdns_server_request_set_flags(struct evdns_server_request *req, int flags);
665 
666 /* Functions to add an answer to an in-progress DNS reply.
667  */
668 EVENT2_EXPORT_SYMBOL
669 int evdns_server_request_add_reply(struct evdns_server_request *req, int section, const char *name, int type, int dns_class, int ttl, int datalen, int is_name, const char *data);
670 EVENT2_EXPORT_SYMBOL
671 int evdns_server_request_add_a_reply(struct evdns_server_request *req, const char *name, int n, const void *addrs, int ttl);
672 EVENT2_EXPORT_SYMBOL
673 int evdns_server_request_add_aaaa_reply(struct evdns_server_request *req, const char *name, int n, const void *addrs, int ttl);
674 EVENT2_EXPORT_SYMBOL
675 int evdns_server_request_add_ptr_reply(struct evdns_server_request *req, struct in_addr *in, const char *inaddr_name, const char *hostname, int ttl);
676 EVENT2_EXPORT_SYMBOL
677 int evdns_server_request_add_cname_reply(struct evdns_server_request *req, const char *name, const char *cname, int ttl);
678 
682 EVENT2_EXPORT_SYMBOL
683 int evdns_server_request_respond(struct evdns_server_request *req, int err);
687 EVENT2_EXPORT_SYMBOL
688 int evdns_server_request_drop(struct evdns_server_request *req);
689 struct sockaddr;
693 EVENT2_EXPORT_SYMBOL
694 int evdns_server_request_get_requesting_addr(struct evdns_server_request *req, struct sockaddr *sa, int addr_len);
695 
697 typedef void (*evdns_getaddrinfo_cb)(int result, struct evutil_addrinfo *res, void *arg);
698 
699 struct evdns_base;
700 struct evdns_getaddrinfo_request;
718 EVENT2_EXPORT_SYMBOL
719 struct evdns_getaddrinfo_request *evdns_getaddrinfo(
720  struct evdns_base *dns_base,
721  const char *nodename, const char *servname,
722  const struct evutil_addrinfo *hints_in,
723  evdns_getaddrinfo_cb cb, void *arg);
724 
725 /* Cancel an in-progress evdns_getaddrinfo. This MUST NOT be called after the
726  * getaddrinfo's callback has been invoked. The resolves will be canceled,
727  * and the callback will be invoked with the error EVUTIL_EAI_CANCEL. */
728 EVENT2_EXPORT_SYMBOL
729 void evdns_getaddrinfo_cancel(struct evdns_getaddrinfo_request *req);
730 
743 EVENT2_EXPORT_SYMBOL
744 int evdns_base_get_nameserver_addr(struct evdns_base *base, int idx,
745  struct sockaddr *sa, ev_socklen_t len);
746 
747 #ifdef __cplusplus
748 }
749 #endif
750 
751 #endif /* !EVENT2_DNS_H_INCLUDED_ */
void(* evdns_debug_log_fn_type)(int is_warning, const char *msg)
A callback that is invoked when a log message is generated.
Definition: dns.h:564
EVENT2_EXPORT_SYMBOL void evdns_set_transaction_id_fn(ev_uint16_t(*fn)(void))
Set a callback that will be invoked to generate transaction IDs.
EVENT2_EXPORT_SYMBOL int evdns_base_nameserver_sockaddr_add(struct evdns_base *base, const struct sockaddr *sa, ev_socklen_t len, unsigned flags)
Add a nameserver by sockaddr.
EVENT2_EXPORT_SYMBOL const char * evdns_err_to_string(int err)
Convert a DNS error code to a string.
EVENT2_EXPORT_SYMBOL void evdns_base_search_clear(struct evdns_base *base)
Clear the list of search domains.
void(* evdns_callback_type)(int result, char type, int count, int ttl, void *addresses, void *arg)
The callback that contains the results from a lookup.
Definition: dns.h:229
EVENT2_EXPORT_SYMBOL void evdns_cancel_request(struct evdns_base *base, struct evdns_request *req)
Cancels a pending DNS resolution request.
EVENT2_EXPORT_SYMBOL int evdns_base_resume(struct evdns_base *base)
Resume normal operation and continue any suspended resolve requests.
EVENT2_EXPORT_SYMBOL void evdns_base_clear_host_addresses(struct evdns_base *base)
Remove all hosts entries that have been loaded into the event_base via evdns_base_load_hosts or via e...
EVENT2_EXPORT_SYMBOL int evdns_base_clear_nameservers_and_suspend(struct evdns_base *base)
Remove all configured nameservers, and suspend all pending resolves.
EVENT2_EXPORT_SYMBOL void evdns_set_log_fn(evdns_debug_log_fn_type fn)
Set the callback function to handle DNS log messages.
EVENT2_EXPORT_SYMBOL void evdns_close_server_port(struct evdns_server_port *port)
Close down a DNS server port, and free associated structures.
EVENT2_EXPORT_SYMBOL int evdns_base_set_option(struct evdns_base *base, const char *option, const char *val)
Set the value of a configuration option.
EVENT2_EXPORT_SYMBOL int evdns_server_request_get_requesting_addr(struct evdns_server_request *req, struct sockaddr *sa, int addr_len)
Get the address that made a DNS request.
EVENT2_EXPORT_SYMBOL struct evdns_server_port * evdns_add_server_port_with_base(struct event_base *base, evutil_socket_t socket, int flags, evdns_request_callback_fn_type callback, void *user_data)
Create a new DNS server port.
EVENT2_EXPORT_SYMBOL struct evdns_request * evdns_base_resolve_reverse_ipv6(struct evdns_base *base, const struct in6_addr *in, int flags, evdns_callback_type callback, void *ptr)
Lookup a PTR record for a given IPv6 address.
EVENT2_EXPORT_SYMBOL struct evdns_request * evdns_base_resolve_reverse(struct evdns_base *base, const struct in_addr *in, int flags, evdns_callback_type callback, void *ptr)
Lookup a PTR record for a given IP address.
#define evutil_socket_t
A type wide enough to hold the output of &quot;socket()&quot; or &quot;accept()&quot;.
Definition: util.h:310
EVENT2_EXPORT_SYMBOL void evdns_base_search_add(struct evdns_base *base, const char *domain)
Add a domain to the list of search domains.
EVENT2_EXPORT_SYMBOL int evdns_server_request_respond(struct evdns_server_request *req, int err)
Send back a response to a DNS request, and free the request structure.
EVENT2_EXPORT_SYMBOL struct evdns_getaddrinfo_request * evdns_getaddrinfo(struct evdns_base *dns_base, const char *nodename, const char *servname, const struct evutil_addrinfo *hints_in, evdns_getaddrinfo_cb cb, void *arg)
Make a non-blocking getaddrinfo request using the dns_base in &#39;dns_base&#39;.
EVENT2_EXPORT_SYMBOL void evdns_server_request_set_flags(struct evdns_server_request *req, int flags)
Sets some flags in a reply we&#39;re building.
EVENT2_EXPORT_SYMBOL struct evdns_base * evdns_base_new(struct event_base *event_base, int initialize_nameservers)
Initialize the asynchronous DNS library.
EVENT2_EXPORT_SYMBOL struct evdns_request * evdns_base_resolve_ipv6(struct evdns_base *base, const char *name, int flags, evdns_callback_type callback, void *ptr)
Lookup an AAAA record for a given name.
Common convenience functions for cross-platform portability and related socket manipulations.
EVENT2_EXPORT_SYMBOL int evdns_server_request_drop(struct evdns_server_request *req)
Free a DNS request without sending back a reply.
EVENT2_EXPORT_SYMBOL int evdns_base_get_nameserver_addr(struct evdns_base *base, int idx, struct sockaddr *sa, ev_socklen_t len)
Retrieve the address of the &#39;idx&#39;th configured nameserver.
void(* evdns_getaddrinfo_cb)(int result, struct evutil_addrinfo *res, void *arg)
Callback for evdns_getaddrinfo.
Definition: dns.h:697
EVENT2_EXPORT_SYMBOL struct evdns_request * evdns_base_resolve_ipv4(struct evdns_base *base, const char *name, int flags, evdns_callback_type callback, void *ptr)
Lookup an A record for a given name.
EVENT2_EXPORT_SYMBOL int evdns_base_count_nameservers(struct evdns_base *base)
Get the number of configured nameservers.
EVENT2_EXPORT_SYMBOL void evdns_base_search_ndots_set(struct evdns_base *base, const int ndots)
Set the &#39;ndots&#39; parameter for searches.
EVENT2_EXPORT_SYMBOL int evdns_base_resolv_conf_parse(struct evdns_base *base, int flags, const char *const filename)
Parse a resolv.conf file.
EVENT2_EXPORT_SYMBOL int evdns_base_nameserver_ip_add(struct evdns_base *base, const char *ip_as_string)
Add a nameserver by string address.
A definition of struct addrinfo for systems that lack it.
Definition: util.h:679
EVENT2_EXPORT_SYMBOL int evdns_base_nameserver_add(struct evdns_base *base, unsigned long int address)
Add a nameserver.
EVENT2_EXPORT_SYMBOL int evdns_base_load_hosts(struct evdns_base *base, const char *hosts_fname)
Load an /etc/hosts-style file from &#39;hosts_fname&#39; into &#39;base&#39;.
EVENT2_EXPORT_SYMBOL void evdns_set_random_bytes_fn(void(*fn)(char *, size_t))
Set a callback used to generate random bytes.
EVENT2_EXPORT_SYMBOL void evdns_base_free(struct evdns_base *base, int fail_requests)
Shut down the asynchronous DNS resolver and terminate all active requests.
EVENT2_EXPORT_SYMBOL int evdns_base_config_windows_nameservers(struct evdns_base *)
Obtain nameserver information using the Windows API.
Structure to hold information and state for a Libevent dispatch loop.
Definition: event.h:217
void(* evdns_request_callback_fn_type)(struct evdns_server_request *, void *)
A callback to implement a DNS server.
Definition: dns.h:620