1#ifndef HEADER_CURL_ASYN_H
2#define HEADER_CURL_ASYN_H
3/***************************************************************************
4 * _ _ ____ _
5 * Project ___| | | | _ \| |
6 * / __| | | | |_) | |
7 * | (__| |_| | _ <| |___
8 * \___|\___/|_| \_\_____|
9 *
10 * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
11 *
12 * This software is licensed as described in the file COPYING, which
13 * you should have received as part of this distribution. The terms
14 * are also available at https://curl.se/docs/copyright.html.
15 *
16 * You may opt to use, copy, modify, merge, publish, distribute and/or sell
17 * copies of the Software, and permit persons to whom the Software is
18 * furnished to do so, under the terms of the COPYING file.
19 *
20 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
21 * KIND, either express or implied.
22 *
23 * SPDX-License-Identifier: curl
24 *
25 ***************************************************************************/
26
27#include "curl_setup.h"
28#include "curl_addrinfo.h"
29
30struct addrinfo;
31struct hostent;
32struct Curl_easy;
33struct connectdata;
34struct Curl_dns_entry;
35
36/*
37 * This header defines all functions in the internal asynch resolver interface.
38 * All asynch resolvers need to provide these functions.
39 * asyn-ares.c and asyn-thread.c are the current implementations of asynch
40 * resolver backends.
41 */
42
43/*
44 * Curl_resolver_global_init()
45 *
46 * Called from curl_global_init() to initialize global resolver environment.
47 * Returning anything else than CURLE_OK fails curl_global_init().
48 */
49int Curl_resolver_global_init(void);
50
51/*
52 * Curl_resolver_global_cleanup()
53 * Called from curl_global_cleanup() to destroy global resolver environment.
54 */
55void Curl_resolver_global_cleanup(void);
56
57/*
58 * Curl_resolver_init()
59 * Called from curl_easy_init() -> Curl_open() to initialize resolver
60 * URL-state specific environment ('resolver' member of the UrlState
61 * structure). Should fill the passed pointer by the initialized handler.
62 * Returning anything else than CURLE_OK fails curl_easy_init() with the
63 * correspondent code.
64 */
65CURLcode Curl_resolver_init(struct Curl_easy *easy, void **resolver);
66
67/*
68 * Curl_resolver_cleanup()
69 * Called from curl_easy_cleanup() -> Curl_close() to cleanup resolver
70 * URL-state specific environment ('resolver' member of the UrlState
71 * structure). Should destroy the handler and free all resources connected to
72 * it.
73 */
74void Curl_resolver_cleanup(void *resolver);
75
76/*
77 * Curl_resolver_duphandle()
78 * Called from curl_easy_duphandle() to duplicate resolver URL-state specific
79 * environment ('resolver' member of the UrlState structure). Should
80 * duplicate the 'from' handle and pass the resulting handle to the 'to'
81 * pointer. Returning anything else than CURLE_OK causes failed
82 * curl_easy_duphandle() call.
83 */
84CURLcode Curl_resolver_duphandle(struct Curl_easy *easy, void **to,
85 void *from);
86
87/*
88 * Curl_resolver_cancel().
89 *
90 * It is called from inside other functions to cancel currently performing
91 * resolver request. Should also free any temporary resources allocated to
92 * perform a request. This never waits for resolver threads to complete.
93 *
94 * It is safe to call this when conn is in any state.
95 */
96void Curl_resolver_cancel(struct Curl_easy *data);
97
98/*
99 * Curl_resolver_kill().
100 *
101 * This acts like Curl_resolver_cancel() except it will block until any threads
102 * associated with the resolver are complete. This never blocks for resolvers
103 * that do not use threads. This is intended to be the "last chance" function
104 * that cleans up an in-progress resolver completely (before its owner is about
105 * to die).
106 *
107 * It is safe to call this when conn is in any state.
108 */
109void Curl_resolver_kill(struct Curl_easy *data);
110
111/* Curl_resolver_getsock()
112 *
113 * This function is called from the multi_getsock() function. 'sock' is a
114 * pointer to an array to hold the file descriptors, with 'numsock' being the
115 * size of that array (in number of entries). This function is supposed to
116 * return bitmask indicating what file descriptors (referring to array indexes
117 * in the 'sock' array) to wait for, read/write.
118 */
119int Curl_resolver_getsock(struct Curl_easy *data, curl_socket_t *sock);
120
121/*
122 * Curl_resolver_is_resolved()
123 *
124 * Called repeatedly to check if a previous name resolve request has
125 * completed. It should also make sure to time-out if the operation seems to
126 * take too long.
127 *
128 * Returns normal CURLcode errors.
129 */
130CURLcode Curl_resolver_is_resolved(struct Curl_easy *data,
131 struct Curl_dns_entry **dns);
132
133/*
134 * Curl_resolver_wait_resolv()
135 *
136 * Waits for a resolve to finish. This function should be avoided since using
137 * this risk getting the multi interface to "hang".
138 *
139 * If 'entry' is non-NULL, make it point to the resolved dns entry
140 *
141 * Returns CURLE_COULDNT_RESOLVE_HOST if the host was not resolved,
142 * CURLE_OPERATION_TIMEDOUT if a time-out occurred, or other errors.
143 */
144CURLcode Curl_resolver_wait_resolv(struct Curl_easy *data,
145 struct Curl_dns_entry **dnsentry);
146
147/*
148 * Curl_resolver_getaddrinfo() - when using this resolver
149 *
150 * Returns name information about the given hostname and port number. If
151 * successful, the 'hostent' is returned and the fourth argument will point to
152 * memory we need to free after use. That memory *MUST* be freed with
153 * Curl_freeaddrinfo(), nothing else.
154 *
155 * Each resolver backend must of course make sure to return data in the
156 * correct format to comply with this.
157 */
158struct Curl_addrinfo *Curl_resolver_getaddrinfo(struct Curl_easy *data,
159 const char *hostname,
160 int port,
161 int *waitp);
162
163#ifndef CURLRES_ASYNCH
164/* convert these functions if an asynch resolver isn't used */
165#define Curl_resolver_cancel(x) Curl_nop_stmt
166#define Curl_resolver_kill(x) Curl_nop_stmt
167#define Curl_resolver_is_resolved(x,y) CURLE_COULDNT_RESOLVE_HOST
168#define Curl_resolver_wait_resolv(x,y) CURLE_COULDNT_RESOLVE_HOST
169#define Curl_resolver_duphandle(x,y,z) CURLE_OK
170#define Curl_resolver_init(x,y) CURLE_OK
171#define Curl_resolver_global_init() CURLE_OK
172#define Curl_resolver_global_cleanup() Curl_nop_stmt
173#define Curl_resolver_cleanup(x) Curl_nop_stmt
174#endif
175
176#ifdef CURLRES_ASYNCH
177#define Curl_resolver_asynch() 1
178#else
179#define Curl_resolver_asynch() 0
180#endif
181
182
183/********** end of generic resolver interface functions *****************/
184#endif /* HEADER_CURL_ASYN_H */
185