1275970Scy/* 2275970Scy * Copyright (c) 2006-2007 Niels Provos <provos@citi.umich.edu> 3275970Scy * Copyright (c) 2007-2012 Niels Provos and Nick Mathewson 4275970Scy * 5275970Scy * Redistribution and use in source and binary forms, with or without 6275970Scy * modification, are permitted provided that the following conditions 7275970Scy * are met: 8275970Scy * 1. Redistributions of source code must retain the above copyright 9275970Scy * notice, this list of conditions and the following disclaimer. 10275970Scy * 2. Redistributions in binary form must reproduce the above copyright 11275970Scy * notice, this list of conditions and the following disclaimer in the 12275970Scy * documentation and/or other materials provided with the distribution. 13275970Scy * 3. The name of the author may not be used to endorse or promote products 14275970Scy * derived from this software without specific prior written permission. 15275970Scy * 16275970Scy * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17275970Scy * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18275970Scy * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19275970Scy * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20275970Scy * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21275970Scy * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22275970Scy * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23275970Scy * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24275970Scy * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25275970Scy * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26275970Scy */ 27275970Scy 28275970Scy/* 29275970Scy * The original DNS code is due to Adam Langley with heavy 30275970Scy * modifications by Nick Mathewson. Adam put his DNS software in the 31275970Scy * public domain. You can find his original copyright below. Please, 32275970Scy * aware that the code as part of Libevent is governed by the 3-clause 33275970Scy * BSD license above. 34275970Scy * 35275970Scy * This software is Public Domain. To view a copy of the public domain dedication, 36275970Scy * visit http://creativecommons.org/licenses/publicdomain/ or send a letter to 37275970Scy * Creative Commons, 559 Nathan Abbott Way, Stanford, California 94305, USA. 38275970Scy * 39275970Scy * I ask and expect, but do not require, that all derivative works contain an 40275970Scy * attribution similar to: 41275970Scy * Parts developed by Adam Langley <agl@imperialviolet.org> 42275970Scy * 43275970Scy * You may wish to replace the word "Parts" with something else depending on 44275970Scy * the amount of original code. 45275970Scy * 46275970Scy * (Derivative works does not include programs which link against, run or include 47275970Scy * the source verbatim in their source distributions) 48275970Scy */ 49275970Scy 50275970Scy/** @file event2/dns.h 51275970Scy * 52275970Scy * Welcome, gentle reader 53275970Scy * 54275970Scy * Async DNS lookups are really a whole lot harder than they should be, 55275970Scy * mostly stemming from the fact that the libc resolver has never been 56275970Scy * very good at them. Before you use this library you should see if libc 57275970Scy * can do the job for you with the modern async call getaddrinfo_a 58275970Scy * (see http://www.imperialviolet.org/page25.html#e498). Otherwise, 59275970Scy * please continue. 60275970Scy * 61275970Scy * The library keeps track of the state of nameservers and will avoid 62275970Scy * them when they go down. Otherwise it will round robin between them. 63275970Scy * 64275970Scy * Quick start guide: 65275970Scy * #include "evdns.h" 66275970Scy * void callback(int result, char type, int count, int ttl, 67275970Scy * void *addresses, void *arg); 68275970Scy * evdns_resolv_conf_parse(DNS_OPTIONS_ALL, "/etc/resolv.conf"); 69275970Scy * evdns_resolve("www.hostname.com", 0, callback, NULL); 70275970Scy * 71275970Scy * When the lookup is complete the callback function is called. The 72275970Scy * first argument will be one of the DNS_ERR_* defines in evdns.h. 73275970Scy * Hopefully it will be DNS_ERR_NONE, in which case type will be 74275970Scy * DNS_IPv4_A, count will be the number of IP addresses, ttl is the time 75275970Scy * which the data can be cached for (in seconds), addresses will point 76275970Scy * to an array of uint32_t's and arg will be whatever you passed to 77275970Scy * evdns_resolve. 78275970Scy * 79275970Scy * Searching: 80275970Scy * 81275970Scy * In order for this library to be a good replacement for glibc's resolver it 82275970Scy * supports searching. This involves setting a list of default domains, in 83275970Scy * which names will be queried for. The number of dots in the query name 84275970Scy * determines the order in which this list is used. 85275970Scy * 86275970Scy * Searching appears to be a single lookup from the point of view of the API, 87275970Scy * although many DNS queries may be generated from a single call to 88275970Scy * evdns_resolve. Searching can also drastically slow down the resolution 89275970Scy * of names. 90275970Scy * 91275970Scy * To disable searching: 92275970Scy * 1. Never set it up. If you never call evdns_resolv_conf_parse or 93275970Scy * evdns_search_add then no searching will occur. 94275970Scy * 95275970Scy * 2. If you do call evdns_resolv_conf_parse then don't pass 96275970Scy * DNS_OPTION_SEARCH (or DNS_OPTIONS_ALL, which implies it). 97275970Scy * 98275970Scy * 3. When calling evdns_resolve, pass the DNS_QUERY_NO_SEARCH flag. 99275970Scy * 100275970Scy * The order of searches depends on the number of dots in the name. If the 101275970Scy * number is greater than the ndots setting then the names is first tried 102275970Scy * globally. Otherwise each search domain is appended in turn. 103275970Scy * 104275970Scy * The ndots setting can either be set from a resolv.conf, or by calling 105275970Scy * evdns_search_ndots_set. 106275970Scy * 107275970Scy * For example, with ndots set to 1 (the default) and a search domain list of 108275970Scy * ["myhome.net"]: 109275970Scy * Query: www 110275970Scy * Order: www.myhome.net, www. 111275970Scy * 112275970Scy * Query: www.abc 113275970Scy * Order: www.abc., www.abc.myhome.net 114275970Scy * 115275970Scy * Internals: 116275970Scy * 117275970Scy * Requests are kept in two queues. The first is the inflight queue. In 118275970Scy * this queue requests have an allocated transaction id and nameserver. 119275970Scy * They will soon be transmitted if they haven't already been. 120275970Scy * 121275970Scy * The second is the waiting queue. The size of the inflight ring is 122275970Scy * limited and all other requests wait in waiting queue for space. This 123275970Scy * bounds the number of concurrent requests so that we don't flood the 124275970Scy * nameserver. Several algorithms require a full walk of the inflight 125275970Scy * queue and so bounding its size keeps thing going nicely under huge 126275970Scy * (many thousands of requests) loads. 127275970Scy * 128275970Scy * If a nameserver loses too many requests it is considered down and we 129275970Scy * try not to use it. After a while we send a probe to that nameserver 130275970Scy * (a lookup for google.com) and, if it replies, we consider it working 131275970Scy * again. If the nameserver fails a probe we wait longer to try again 132275970Scy * with the next probe. 133275970Scy */ 134275970Scy 135275970Scy#ifndef EVENT2_DNS_H_INCLUDED_ 136275970Scy#define EVENT2_DNS_H_INCLUDED_ 137275970Scy 138275970Scy#include <event2/visibility.h> 139275970Scy 140275970Scy#ifdef __cplusplus 141275970Scyextern "C" { 142275970Scy#endif 143275970Scy 144275970Scy/* For integer types. */ 145275970Scy#include <event2/util.h> 146275970Scy 147275970Scy/** Error codes 0-5 are as described in RFC 1035. */ 148275970Scy#define DNS_ERR_NONE 0 149275970Scy/** The name server was unable to interpret the query */ 150275970Scy#define DNS_ERR_FORMAT 1 151275970Scy/** The name server was unable to process this query due to a problem with the 152275970Scy * name server */ 153275970Scy#define DNS_ERR_SERVERFAILED 2 154275970Scy/** The domain name does not exist */ 155275970Scy#define DNS_ERR_NOTEXIST 3 156275970Scy/** The name server does not support the requested kind of query */ 157275970Scy#define DNS_ERR_NOTIMPL 4 158275970Scy/** The name server refuses to reform the specified operation for policy 159275970Scy * reasons */ 160275970Scy#define DNS_ERR_REFUSED 5 161275970Scy/** The reply was truncated or ill-formatted */ 162275970Scy#define DNS_ERR_TRUNCATED 65 163275970Scy/** An unknown error occurred */ 164275970Scy#define DNS_ERR_UNKNOWN 66 165275970Scy/** Communication with the server timed out */ 166275970Scy#define DNS_ERR_TIMEOUT 67 167275970Scy/** The request was canceled because the DNS subsystem was shut down. */ 168275970Scy#define DNS_ERR_SHUTDOWN 68 169275970Scy/** The request was canceled via a call to evdns_cancel_request */ 170275970Scy#define DNS_ERR_CANCEL 69 171275970Scy/** There were no answers and no error condition in the DNS packet. 172275970Scy * This can happen when you ask for an address that exists, but a record 173275970Scy * type that doesn't. */ 174275970Scy#define DNS_ERR_NODATA 70 175275970Scy 176275970Scy#define DNS_IPv4_A 1 177275970Scy#define DNS_PTR 2 178275970Scy#define DNS_IPv6_AAAA 3 179275970Scy 180275970Scy#define DNS_QUERY_NO_SEARCH 1 181275970Scy 182275970Scy#define DNS_OPTION_SEARCH 1 183275970Scy#define DNS_OPTION_NAMESERVERS 2 184275970Scy#define DNS_OPTION_MISC 4 185275970Scy#define DNS_OPTION_HOSTSFILE 8 186275970Scy#define DNS_OPTIONS_ALL 15 187275970Scy 188275970Scy/* Obsolete name for DNS_QUERY_NO_SEARCH */ 189275970Scy#define DNS_NO_SEARCH DNS_QUERY_NO_SEARCH 190275970Scy 191275970Scy/** 192275970Scy * The callback that contains the results from a lookup. 193275970Scy * - result is one of the DNS_ERR_* values (DNS_ERR_NONE for success) 194275970Scy * - type is either DNS_IPv4_A or DNS_PTR or DNS_IPv6_AAAA 195275970Scy * - count contains the number of addresses of form type 196275970Scy * - ttl is the number of seconds the resolution may be cached for. 197275970Scy * - addresses needs to be cast according to type. It will be an array of 198275970Scy * 4-byte sequences for ipv4, or an array of 16-byte sequences for ipv6, 199275970Scy * or a nul-terminated string for PTR. 200275970Scy */ 201275970Scytypedef void (*evdns_callback_type) (int result, char type, int count, int ttl, void *addresses, void *arg); 202275970Scy 203275970Scystruct evdns_base; 204275970Scystruct event_base; 205275970Scy 206275970Scy/** Flag for evdns_base_new: process resolv.conf. */ 207275970Scy#define EVDNS_BASE_INITIALIZE_NAMESERVERS 1 208275970Scy/** Flag for evdns_base_new: Do not prevent the libevent event loop from 209275970Scy * exiting when we have no active dns requests. */ 210275970Scy#define EVDNS_BASE_DISABLE_WHEN_INACTIVE 0x8000 211275970Scy 212275970Scy/** 213275970Scy Initialize the asynchronous DNS library. 214275970Scy 215275970Scy This function initializes support for non-blocking name resolution by 216275970Scy calling evdns_resolv_conf_parse() on UNIX and 217275970Scy evdns_config_windows_nameservers() on Windows. 218275970Scy 219275970Scy @param event_base the event base to associate the dns client with 220275970Scy @param flags any of EVDNS_BASE_INITIALIZE_NAMESERVERS| 221275970Scy EVDNS_BASE_DISABLE_WHEN_INACTIVE 222275970Scy @return evdns_base object if successful, or NULL if an error occurred. 223275970Scy @see evdns_base_free() 224275970Scy */ 225275970ScyEVENT2_EXPORT_SYMBOL 226275970Scystruct evdns_base * evdns_base_new(struct event_base *event_base, int initialize_nameservers); 227275970Scy 228275970Scy 229275970Scy/** 230275970Scy Shut down the asynchronous DNS resolver and terminate all active requests. 231275970Scy 232275970Scy If the 'fail_requests' option is enabled, all active requests will return 233275970Scy an empty result with the error flag set to DNS_ERR_SHUTDOWN. Otherwise, 234275970Scy the requests will be silently discarded. 235275970Scy 236275970Scy @param evdns_base the evdns base to free 237275970Scy @param fail_requests if zero, active requests will be aborted; if non-zero, 238275970Scy active requests will return DNS_ERR_SHUTDOWN. 239275970Scy @see evdns_base_new() 240275970Scy */ 241275970ScyEVENT2_EXPORT_SYMBOL 242275970Scyvoid evdns_base_free(struct evdns_base *base, int fail_requests); 243275970Scy 244275970Scy/** 245275970Scy Remove all hosts entries that have been loaded into the event_base via 246275970Scy evdns_base_load_hosts or via event_base_resolv_conf_parse. 247275970Scy 248275970Scy @param evdns_base the evdns base to remove outdated host addresses from 249275970Scy */ 250275970ScyEVENT2_EXPORT_SYMBOL 251275970Scyvoid evdns_base_clear_host_addresses(struct evdns_base *base); 252275970Scy 253275970Scy/** 254275970Scy Convert a DNS error code to a string. 255275970Scy 256275970Scy @param err the DNS error code 257275970Scy @return a string containing an explanation of the error code 258275970Scy*/ 259275970ScyEVENT2_EXPORT_SYMBOL 260275970Scyconst char *evdns_err_to_string(int err); 261275970Scy 262275970Scy 263275970Scy/** 264275970Scy Add a nameserver. 265275970Scy 266275970Scy The address should be an IPv4 address in network byte order. 267275970Scy The type of address is chosen so that it matches in_addr.s_addr. 268275970Scy 269275970Scy @param base the evdns_base to which to add the name server 270275970Scy @param address an IP address in network byte order 271275970Scy @return 0 if successful, or -1 if an error occurred 272275970Scy @see evdns_base_nameserver_ip_add() 273275970Scy */ 274275970ScyEVENT2_EXPORT_SYMBOL 275275970Scyint evdns_base_nameserver_add(struct evdns_base *base, 276275970Scy unsigned long int address); 277275970Scy 278275970Scy/** 279275970Scy Get the number of configured nameservers. 280275970Scy 281275970Scy This returns the number of configured nameservers (not necessarily the 282275970Scy number of running nameservers). This is useful for double-checking 283275970Scy whether our calls to the various nameserver configuration functions 284275970Scy have been successful. 285275970Scy 286275970Scy @param base the evdns_base to which to apply this operation 287275970Scy @return the number of configured nameservers 288275970Scy @see evdns_base_nameserver_add() 289275970Scy */ 290275970ScyEVENT2_EXPORT_SYMBOL 291275970Scyint evdns_base_count_nameservers(struct evdns_base *base); 292275970Scy 293275970Scy/** 294275970Scy Remove all configured nameservers, and suspend all pending resolves. 295275970Scy 296275970Scy Resolves will not necessarily be re-attempted until evdns_base_resume() is called. 297275970Scy 298275970Scy @param base the evdns_base to which to apply this operation 299275970Scy @return 0 if successful, or -1 if an error occurred 300275970Scy @see evdns_base_resume() 301275970Scy */ 302275970ScyEVENT2_EXPORT_SYMBOL 303275970Scyint evdns_base_clear_nameservers_and_suspend(struct evdns_base *base); 304275970Scy 305275970Scy 306275970Scy/** 307275970Scy Resume normal operation and continue any suspended resolve requests. 308275970Scy 309275970Scy Re-attempt resolves left in limbo after an earlier call to 310275970Scy evdns_base_clear_nameservers_and_suspend(). 311275970Scy 312275970Scy @param base the evdns_base to which to apply this operation 313275970Scy @return 0 if successful, or -1 if an error occurred 314275970Scy @see evdns_base_clear_nameservers_and_suspend() 315275970Scy */ 316275970ScyEVENT2_EXPORT_SYMBOL 317275970Scyint evdns_base_resume(struct evdns_base *base); 318275970Scy 319275970Scy/** 320275970Scy Add a nameserver by string address. 321275970Scy 322275970Scy This function parses a n IPv4 or IPv6 address from a string and adds it as a 323275970Scy nameserver. It supports the following formats: 324275970Scy - [IPv6Address]:port 325275970Scy - [IPv6Address] 326275970Scy - IPv6Address 327275970Scy - IPv4Address:port 328275970Scy - IPv4Address 329275970Scy 330275970Scy If no port is specified, it defaults to 53. 331275970Scy 332275970Scy @param base the evdns_base to which to apply this operation 333275970Scy @return 0 if successful, or -1 if an error occurred 334275970Scy @see evdns_base_nameserver_add() 335275970Scy */ 336275970ScyEVENT2_EXPORT_SYMBOL 337275970Scyint evdns_base_nameserver_ip_add(struct evdns_base *base, 338275970Scy const char *ip_as_string); 339275970Scy 340275970Scy/** 341275970Scy Add a nameserver by sockaddr. 342275970Scy **/ 343275970ScyEVENT2_EXPORT_SYMBOL 344275970Scyint 345275970Scyevdns_base_nameserver_sockaddr_add(struct evdns_base *base, 346275970Scy const struct sockaddr *sa, ev_socklen_t len, unsigned flags); 347275970Scy 348275970Scystruct evdns_request; 349275970Scy 350275970Scy/** 351275970Scy Lookup an A record for a given name. 352275970Scy 353275970Scy @param base the evdns_base to which to apply this operation 354275970Scy @param name a DNS hostname 355275970Scy @param flags either 0, or DNS_QUERY_NO_SEARCH to disable searching for this query. 356275970Scy @param callback a callback function to invoke when the request is completed 357275970Scy @param ptr an argument to pass to the callback function 358275970Scy @return an evdns_request object if successful, or NULL if an error occurred. 359275970Scy @see evdns_resolve_ipv6(), evdns_resolve_reverse(), evdns_resolve_reverse_ipv6(), evdns_cancel_request() 360275970Scy */ 361275970ScyEVENT2_EXPORT_SYMBOL 362275970Scystruct evdns_request *evdns_base_resolve_ipv4(struct evdns_base *base, const char *name, int flags, evdns_callback_type callback, void *ptr); 363275970Scy 364275970Scy/** 365275970Scy Lookup an AAAA record for a given name. 366275970Scy 367275970Scy @param base the evdns_base to which to apply this operation 368275970Scy @param name a DNS hostname 369275970Scy @param flags either 0, or DNS_QUERY_NO_SEARCH to disable searching for this query. 370275970Scy @param callback a callback function to invoke when the request is completed 371275970Scy @param ptr an argument to pass to the callback function 372275970Scy @return an evdns_request object if successful, or NULL if an error occurred. 373275970Scy @see evdns_resolve_ipv4(), evdns_resolve_reverse(), evdns_resolve_reverse_ipv6(), evdns_cancel_request() 374275970Scy */ 375275970ScyEVENT2_EXPORT_SYMBOL 376275970Scystruct evdns_request *evdns_base_resolve_ipv6(struct evdns_base *base, const char *name, int flags, evdns_callback_type callback, void *ptr); 377275970Scy 378275970Scystruct in_addr; 379275970Scystruct in6_addr; 380275970Scy 381275970Scy/** 382275970Scy Lookup a PTR record for a given IP address. 383275970Scy 384275970Scy @param base the evdns_base to which to apply this operation 385275970Scy @param in an IPv4 address 386275970Scy @param flags either 0, or DNS_QUERY_NO_SEARCH to disable searching for this query. 387275970Scy @param callback a callback function to invoke when the request is completed 388275970Scy @param ptr an argument to pass to the callback function 389275970Scy @return an evdns_request object if successful, or NULL if an error occurred. 390275970Scy @see evdns_resolve_reverse_ipv6(), evdns_cancel_request() 391275970Scy */ 392275970ScyEVENT2_EXPORT_SYMBOL 393275970Scystruct evdns_request *evdns_base_resolve_reverse(struct evdns_base *base, const struct in_addr *in, int flags, evdns_callback_type callback, void *ptr); 394275970Scy 395275970Scy 396275970Scy/** 397275970Scy Lookup a PTR record for a given IPv6 address. 398275970Scy 399275970Scy @param base the evdns_base to which to apply this operation 400275970Scy @param in an IPv6 address 401275970Scy @param flags either 0, or DNS_QUERY_NO_SEARCH to disable searching for this query. 402275970Scy @param callback a callback function to invoke when the request is completed 403275970Scy @param ptr an argument to pass to the callback function 404275970Scy @return an evdns_request object if successful, or NULL if an error occurred. 405275970Scy @see evdns_resolve_reverse_ipv6(), evdns_cancel_request() 406275970Scy */ 407275970ScyEVENT2_EXPORT_SYMBOL 408275970Scystruct evdns_request *evdns_base_resolve_reverse_ipv6(struct evdns_base *base, const struct in6_addr *in, int flags, evdns_callback_type callback, void *ptr); 409275970Scy 410275970Scy/** 411275970Scy Cancels a pending DNS resolution request. 412275970Scy 413275970Scy @param base the evdns_base that was used to make the request 414275970Scy @param req the evdns_request that was returned by calling a resolve function 415275970Scy @see evdns_base_resolve_ipv4(), evdns_base_resolve_ipv6, evdns_base_resolve_reverse 416275970Scy*/ 417275970ScyEVENT2_EXPORT_SYMBOL 418275970Scyvoid evdns_cancel_request(struct evdns_base *base, struct evdns_request *req); 419275970Scy 420275970Scy/** 421275970Scy Set the value of a configuration option. 422275970Scy 423275970Scy The currently available configuration options are: 424275970Scy 425275970Scy ndots, timeout, max-timeouts, max-inflight, attempts, randomize-case, 426275970Scy bind-to, initial-probe-timeout, getaddrinfo-allow-skew. 427275970Scy 428275970Scy In versions before Libevent 2.0.3-alpha, the option name needed to end with 429275970Scy a colon. 430275970Scy 431275970Scy @param base the evdns_base to which to apply this operation 432275970Scy @param option the name of the configuration option to be modified 433275970Scy @param val the value to be set 434275970Scy @return 0 if successful, or -1 if an error occurred 435275970Scy */ 436275970ScyEVENT2_EXPORT_SYMBOL 437275970Scyint evdns_base_set_option(struct evdns_base *base, const char *option, const char *val); 438275970Scy 439275970Scy 440275970Scy/** 441275970Scy Parse a resolv.conf file. 442275970Scy 443275970Scy The 'flags' parameter determines what information is parsed from the 444275970Scy resolv.conf file. See the man page for resolv.conf for the format of this 445275970Scy file. 446275970Scy 447275970Scy The following directives are not parsed from the file: sortlist, rotate, 448275970Scy no-check-names, inet6, debug. 449275970Scy 450275970Scy If this function encounters an error, the possible return values are: 1 = 451275970Scy failed to open file, 2 = failed to stat file, 3 = file too large, 4 = out of 452275970Scy memory, 5 = short read from file, 6 = no nameservers listed in the file 453275970Scy 454275970Scy @param base the evdns_base to which to apply this operation 455275970Scy @param flags any of DNS_OPTION_NAMESERVERS|DNS_OPTION_SEARCH|DNS_OPTION_MISC| 456290000Sglebius DNS_OPTION_HOSTSFILE|DNS_OPTIONS_ALL 457275970Scy @param filename the path to the resolv.conf file 458275970Scy @return 0 if successful, or various positive error codes if an error 459275970Scy occurred (see above) 460275970Scy @see resolv.conf(3), evdns_config_windows_nameservers() 461275970Scy */ 462275970ScyEVENT2_EXPORT_SYMBOL 463275970Scyint evdns_base_resolv_conf_parse(struct evdns_base *base, int flags, const char *const filename); 464275970Scy 465275970Scy/** 466275970Scy Load an /etc/hosts-style file from 'hosts_fname' into 'base'. 467275970Scy 468275970Scy If hosts_fname is NULL, add minimal entries for localhost, and nothing 469275970Scy else. 470275970Scy 471275970Scy Note that only evdns_getaddrinfo uses the /etc/hosts entries. 472275970Scy 473275970Scy This function does not replace previously loaded hosts entries; to do that, 474275970Scy call evdns_base_clear_host_addresses first. 475275970Scy 476275970Scy Return 0 on success, negative on failure. 477275970Scy*/ 478275970ScyEVENT2_EXPORT_SYMBOL 479275970Scyint evdns_base_load_hosts(struct evdns_base *base, const char *hosts_fname); 480275970Scy 481275970Scy/** 482275970Scy Obtain nameserver information using the Windows API. 483275970Scy 484275970Scy Attempt to configure a set of nameservers based on platform settings on 485275970Scy a win32 host. Preferentially tries to use GetNetworkParams; if that fails, 486275970Scy looks in the registry. 487275970Scy 488275970Scy @return 0 if successful, or -1 if an error occurred 489275970Scy @see evdns_resolv_conf_parse() 490275970Scy */ 491275970Scy#ifdef _WIN32 492275970ScyEVENT2_EXPORT_SYMBOL 493275970Scyint evdns_base_config_windows_nameservers(struct evdns_base *); 494275970Scy#define EVDNS_BASE_CONFIG_WINDOWS_NAMESERVERS_IMPLEMENTED 495275970Scy#endif 496275970Scy 497275970Scy 498275970Scy/** 499275970Scy Clear the list of search domains. 500275970Scy */ 501275970ScyEVENT2_EXPORT_SYMBOL 502275970Scyvoid evdns_base_search_clear(struct evdns_base *base); 503275970Scy 504275970Scy 505275970Scy/** 506275970Scy Add a domain to the list of search domains 507275970Scy 508275970Scy @param domain the domain to be added to the search list 509275970Scy */ 510275970ScyEVENT2_EXPORT_SYMBOL 511275970Scyvoid evdns_base_search_add(struct evdns_base *base, const char *domain); 512275970Scy 513275970Scy 514275970Scy/** 515275970Scy Set the 'ndots' parameter for searches. 516275970Scy 517275970Scy Sets the number of dots which, when found in a name, causes 518275970Scy the first query to be without any search domain. 519275970Scy 520275970Scy @param ndots the new ndots parameter 521275970Scy */ 522275970ScyEVENT2_EXPORT_SYMBOL 523275970Scyvoid evdns_base_search_ndots_set(struct evdns_base *base, const int ndots); 524275970Scy 525275970Scy/** 526275970Scy A callback that is invoked when a log message is generated 527275970Scy 528275970Scy @param is_warning indicates if the log message is a 'warning' 529275970Scy @param msg the content of the log message 530275970Scy */ 531275970Scytypedef void (*evdns_debug_log_fn_type)(int is_warning, const char *msg); 532275970Scy 533275970Scy 534275970Scy/** 535275970Scy Set the callback function to handle DNS log messages. If this 536275970Scy callback is not set, evdns log messages are handled with the regular 537275970Scy Libevent logging system. 538275970Scy 539275970Scy @param fn the callback to be invoked when a log message is generated 540275970Scy */ 541275970ScyEVENT2_EXPORT_SYMBOL 542275970Scyvoid evdns_set_log_fn(evdns_debug_log_fn_type fn); 543275970Scy 544275970Scy/** 545275970Scy Set a callback that will be invoked to generate transaction IDs. By 546275970Scy default, we pick transaction IDs based on the current clock time, which 547275970Scy is bad for security. 548275970Scy 549275970Scy @param fn the new callback, or NULL to use the default. 550275970Scy 551275970Scy NOTE: This function has no effect in Libevent 2.0.4-alpha and later, 552275970Scy since Libevent now provides its own secure RNG. 553275970Scy */ 554275970ScyEVENT2_EXPORT_SYMBOL 555275970Scyvoid evdns_set_transaction_id_fn(ev_uint16_t (*fn)(void)); 556275970Scy 557275970Scy/** 558275970Scy Set a callback used to generate random bytes. By default, we use 559275970Scy the same function as passed to evdns_set_transaction_id_fn to generate 560275970Scy bytes two at a time. If a function is provided here, it's also used 561275970Scy to generate transaction IDs. 562275970Scy 563275970Scy NOTE: This function has no effect in Libevent 2.0.4-alpha and later, 564275970Scy since Libevent now provides its own secure RNG. 565275970Scy*/ 566275970ScyEVENT2_EXPORT_SYMBOL 567275970Scyvoid evdns_set_random_bytes_fn(void (*fn)(char *, size_t)); 568275970Scy 569275970Scy/* 570275970Scy * Functions used to implement a DNS server. 571275970Scy */ 572275970Scy 573275970Scystruct evdns_server_request; 574275970Scystruct evdns_server_question; 575275970Scy 576275970Scy/** 577275970Scy A callback to implement a DNS server. The callback function receives a DNS 578275970Scy request. It should then optionally add a number of answers to the reply 579275970Scy using the evdns_server_request_add_*_reply functions, before calling either 580275970Scy evdns_server_request_respond to send the reply back, or 581275970Scy evdns_server_request_drop to decline to answer the request. 582275970Scy 583275970Scy @param req A newly received request 584275970Scy @param user_data A pointer that was passed to 585275970Scy evdns_add_server_port_with_base(). 586275970Scy */ 587275970Scytypedef void (*evdns_request_callback_fn_type)(struct evdns_server_request *, void *); 588275970Scy#define EVDNS_ANSWER_SECTION 0 589275970Scy#define EVDNS_AUTHORITY_SECTION 1 590275970Scy#define EVDNS_ADDITIONAL_SECTION 2 591275970Scy 592275970Scy#define EVDNS_TYPE_A 1 593275970Scy#define EVDNS_TYPE_NS 2 594275970Scy#define EVDNS_TYPE_CNAME 5 595275970Scy#define EVDNS_TYPE_SOA 6 596275970Scy#define EVDNS_TYPE_PTR 12 597275970Scy#define EVDNS_TYPE_MX 15 598275970Scy#define EVDNS_TYPE_TXT 16 599275970Scy#define EVDNS_TYPE_AAAA 28 600275970Scy 601275970Scy#define EVDNS_QTYPE_AXFR 252 602275970Scy#define EVDNS_QTYPE_ALL 255 603275970Scy 604275970Scy#define EVDNS_CLASS_INET 1 605275970Scy 606275970Scy/* flags that can be set in answers; as part of the err parameter */ 607275970Scy#define EVDNS_FLAGS_AA 0x400 608275970Scy#define EVDNS_FLAGS_RD 0x080 609275970Scy 610275970Scy/** Create a new DNS server port. 611275970Scy 612275970Scy @param base The event base to handle events for the server port. 613275970Scy @param socket A UDP socket to accept DNS requests. 614275970Scy @param flags Always 0 for now. 615275970Scy @param callback A function to invoke whenever we get a DNS request 616275970Scy on the socket. 617275970Scy @param user_data Data to pass to the callback. 618275970Scy @return an evdns_server_port structure for this server port. 619275970Scy */ 620275970ScyEVENT2_EXPORT_SYMBOL 621275970Scystruct 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); 622275970Scy/** Close down a DNS server port, and free associated structures. */ 623275970ScyEVENT2_EXPORT_SYMBOL 624275970Scyvoid evdns_close_server_port(struct evdns_server_port *port); 625275970Scy 626275970Scy/** Sets some flags in a reply we're building. 627275970Scy Allows setting of the AA or RD flags 628275970Scy */ 629275970ScyEVENT2_EXPORT_SYMBOL 630275970Scyvoid evdns_server_request_set_flags(struct evdns_server_request *req, int flags); 631275970Scy 632275970Scy/* Functions to add an answer to an in-progress DNS reply. 633275970Scy */ 634275970ScyEVENT2_EXPORT_SYMBOL 635275970Scyint 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); 636275970ScyEVENT2_EXPORT_SYMBOL 637275970Scyint evdns_server_request_add_a_reply(struct evdns_server_request *req, const char *name, int n, const void *addrs, int ttl); 638275970ScyEVENT2_EXPORT_SYMBOL 639275970Scyint evdns_server_request_add_aaaa_reply(struct evdns_server_request *req, const char *name, int n, const void *addrs, int ttl); 640275970ScyEVENT2_EXPORT_SYMBOL 641275970Scyint evdns_server_request_add_ptr_reply(struct evdns_server_request *req, struct in_addr *in, const char *inaddr_name, const char *hostname, int ttl); 642275970ScyEVENT2_EXPORT_SYMBOL 643275970Scyint evdns_server_request_add_cname_reply(struct evdns_server_request *req, const char *name, const char *cname, int ttl); 644275970Scy 645275970Scy/** 646275970Scy Send back a response to a DNS request, and free the request structure. 647275970Scy*/ 648275970ScyEVENT2_EXPORT_SYMBOL 649275970Scyint evdns_server_request_respond(struct evdns_server_request *req, int err); 650275970Scy/** 651275970Scy Free a DNS request without sending back a reply. 652275970Scy*/ 653275970ScyEVENT2_EXPORT_SYMBOL 654275970Scyint evdns_server_request_drop(struct evdns_server_request *req); 655275970Scystruct sockaddr; 656275970Scy/** 657275970Scy Get the address that made a DNS request. 658275970Scy */ 659275970ScyEVENT2_EXPORT_SYMBOL 660275970Scyint evdns_server_request_get_requesting_addr(struct evdns_server_request *req, struct sockaddr *sa, int addr_len); 661275970Scy 662275970Scy/** Callback for evdns_getaddrinfo. */ 663275970Scytypedef void (*evdns_getaddrinfo_cb)(int result, struct evutil_addrinfo *res, void *arg); 664275970Scy 665275970Scystruct evdns_base; 666275970Scystruct evdns_getaddrinfo_request; 667275970Scy/** Make a non-blocking getaddrinfo request using the dns_base in 'dns_base'. 668275970Scy * 669275970Scy * If we can answer the request immediately (with an error or not!), then we 670275970Scy * invoke cb immediately and return NULL. Otherwise we return 671275970Scy * an evdns_getaddrinfo_request and invoke cb later. 672275970Scy * 673275970Scy * When the callback is invoked, we pass as its first argument the error code 674275970Scy * that getaddrinfo would return (or 0 for no error). As its second argument, 675275970Scy * we pass the evutil_addrinfo structures we found (or NULL on error). We 676275970Scy * pass 'arg' as the third argument. 677275970Scy * 678275970Scy * Limitations: 679275970Scy * 680275970Scy * - The AI_V4MAPPED and AI_ALL flags are not currently implemented. 681275970Scy * - For ai_socktype, we only handle SOCKTYPE_STREAM, SOCKTYPE_UDP, and 0. 682275970Scy * - For ai_protocol, we only handle IPPROTO_TCP, IPPROTO_UDP, and 0. 683275970Scy */ 684275970ScyEVENT2_EXPORT_SYMBOL 685275970Scystruct evdns_getaddrinfo_request *evdns_getaddrinfo( 686275970Scy struct evdns_base *dns_base, 687275970Scy const char *nodename, const char *servname, 688275970Scy const struct evutil_addrinfo *hints_in, 689275970Scy evdns_getaddrinfo_cb cb, void *arg); 690275970Scy 691275970Scy/* Cancel an in-progress evdns_getaddrinfo. This MUST NOT be called after the 692275970Scy * getaddrinfo's callback has been invoked. The resolves will be canceled, 693275970Scy * and the callback will be invoked with the error EVUTIL_EAI_CANCEL. */ 694275970ScyEVENT2_EXPORT_SYMBOL 695275970Scyvoid evdns_getaddrinfo_cancel(struct evdns_getaddrinfo_request *req); 696275970Scy 697290000Sglebius/** 698290000Sglebius Retrieve the address of the 'idx'th configured nameserver. 699290000Sglebius 700290000Sglebius @param base The evdns_base to examine. 701290000Sglebius @param idx The index of the nameserver to get the address of. 702290000Sglebius @param sa A location to receive the server's address. 703290000Sglebius @param len The number of bytes available at sa. 704290000Sglebius 705290000Sglebius @return the number of bytes written into sa on success. On failure, returns 706290000Sglebius -1 if idx is greater than the number of configured nameservers, or a 707290000Sglebius value greater than 'len' if len was not high enough. 708290000Sglebius */ 709290000SglebiusEVENT2_EXPORT_SYMBOL 710290000Sglebiusint evdns_base_get_nameserver_addr(struct evdns_base *base, int idx, 711290000Sglebius struct sockaddr *sa, ev_socklen_t len); 712290000Sglebius 713275970Scy#ifdef __cplusplus 714275970Scy} 715275970Scy#endif 716275970Scy 717275970Scy#endif /* !EVENT2_DNS_H_INCLUDED_ */ 718