1#ifndef HEADER_CURL_ASYN_H
2#define HEADER_CURL_ASYN_H
3/***************************************************************************
4 * _ _ ____ _
5 * Project ___| | | | _ \| |
6 * / __| | | | |_) | |
7 * | (__| |_| | _ <| |___
8 * \___|\___/|_| \_\_____|
9 *
10 * Copyright (C) 1998 - 2021, 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 ***************************************************************************/
24
25#include "curl_setup.h"
26#include "curl_addrinfo.h"
27
28struct addrinfo;
29struct hostent;
30struct Curl_easy;
31struct connectdata;
32struct Curl_dns_entry;
33
34/*
35 * This header defines all functions in the internal asynch resolver interface.
36 * All asynch resolvers need to provide these functions.
37 * asyn-ares.c and asyn-thread.c are the current implementations of asynch
38 * resolver backends.
39 */
40
41/*
42 * Curl_resolver_global_init()
43 *
44 * Called from curl_global_init() to initialize global resolver environment.
45 * Returning anything else than CURLE_OK fails curl_global_init().
46 */
47int Curl_resolver_global_init(void);
48
49/*
50 * Curl_resolver_global_cleanup()
51 * Called from curl_global_cleanup() to destroy global resolver environment.
52 */
53void Curl_resolver_global_cleanup(void);
54
55/*
56 * Curl_resolver_init()
57 * Called from curl_easy_init() -> Curl_open() to initialize resolver
58 * URL-state specific environment ('resolver' member of the UrlState
59 * structure). Should fill the passed pointer by the initialized handler.
60 * Returning anything else than CURLE_OK fails curl_easy_init() with the
61 * correspondent code.
62 */
63CURLcode Curl_resolver_init(struct Curl_easy *easy, void **resolver);
64
65/*
66 * Curl_resolver_cleanup()
67 * Called from curl_easy_cleanup() -> Curl_close() to cleanup resolver
68 * URL-state specific environment ('resolver' member of the UrlState
69 * structure). Should destroy the handler and free all resources connected to
70 * it.
71 */
72void Curl_resolver_cleanup(void *resolver);
73
74/*
75 * Curl_resolver_duphandle()
76 * Called from curl_easy_duphandle() to duplicate resolver URL-state specific
77 * environment ('resolver' member of the UrlState structure). Should
78 * duplicate the 'from' handle and pass the resulting handle to the 'to'
79 * pointer. Returning anything else than CURLE_OK causes failed
80 * curl_easy_duphandle() call.
81 */
82CURLcode Curl_resolver_duphandle(struct Curl_easy *easy, void **to,
83 void *from);
84
85/*
86 * Curl_resolver_cancel().
87 *
88 * It is called from inside other functions to cancel currently performing
89 * resolver request. Should also free any temporary resources allocated to
90 * perform a request. This never waits for resolver threads to complete.
91 *
92 * It is safe to call this when conn is in any state.
93 */
94void Curl_resolver_cancel(struct Curl_easy *data);
95
96/*
97 * Curl_resolver_kill().
98 *
99 * This acts like Curl_resolver_cancel() except it will block until any threads
100 * associated with the resolver are complete. This never blocks for resolvers
101 * that do not use threads. This is intended to be the "last chance" function
102 * that cleans up an in-progress resolver completely (before its owner is about
103 * to die).
104 *
105 * It is safe to call this when conn is in any state.
106 */
107void Curl_resolver_kill(struct Curl_easy *data);
108
109/* Curl_resolver_getsock()
110 *
111 * This function is called from the multi_getsock() function. 'sock' is a
112 * pointer to an array to hold the file descriptors, with 'numsock' being the
113 * size of that array (in number of entries). This function is supposed to
114 * return bitmask indicating what file descriptors (referring to array indexes
115 * in the 'sock' array) to wait for, read/write.
116 */
117int Curl_resolver_getsock(struct Curl_easy *data, curl_socket_t *sock);
118
119/*
120 * Curl_resolver_is_resolved()
121 *
122 * Called repeatedly to check if a previous name resolve request has
123 * completed. It should also make sure to time-out if the operation seems to
124 * take too long.
125 *
126 * Returns normal CURLcode errors.
127 */
128CURLcode Curl_resolver_is_resolved(struct Curl_easy *data,
129 struct Curl_dns_entry **dns);
130
131/*
132 * Curl_resolver_wait_resolv()
133 *
134 * Waits for a resolve to finish. This function should be avoided since using
135 * this risk getting the multi interface to "hang".
136 *
137 * If 'entry' is non-NULL, make it point to the resolved dns entry
138 *
139 * Returns CURLE_COULDNT_RESOLVE_HOST if the host was not resolved,
140 * CURLE_OPERATION_TIMEDOUT if a time-out occurred, or other errors.
141 */
142CURLcode Curl_resolver_wait_resolv(struct Curl_easy *data,
143 struct Curl_dns_entry **dnsentry);
144
145/*
146 * Curl_resolver_getaddrinfo() - when using this resolver
147 *
148 * Returns name information about the given hostname and port number. If
149 * successful, the 'hostent' is returned and the forth argument will point to
150 * memory we need to free after use. That memory *MUST* be freed with
151 * Curl_freeaddrinfo(), nothing else.
152 *
153 * Each resolver backend must of course make sure to return data in the
154 * correct format to comply with this.
155 */
156struct Curl_addrinfo *Curl_resolver_getaddrinfo(struct Curl_easy *data,
157 const char *hostname,
158 int port,
159 int *waitp);
160
161#ifndef CURLRES_ASYNCH
162/* convert these functions if an asynch resolver isn't used */
163#define Curl_resolver_cancel(x) Curl_nop_stmt
164#define Curl_resolver_kill(x) Curl_nop_stmt
165#define Curl_resolver_is_resolved(x,y) CURLE_COULDNT_RESOLVE_HOST
166#define Curl_resolver_wait_resolv(x,y) CURLE_COULDNT_RESOLVE_HOST
167#define Curl_resolver_duphandle(x,y,z) CURLE_OK
168#define Curl_resolver_init(x,y) CURLE_OK
169#define Curl_resolver_global_init() CURLE_OK
170#define Curl_resolver_global_cleanup() Curl_nop_stmt
171#define Curl_resolver_cleanup(x) Curl_nop_stmt
172#endif
173
174#ifdef CURLRES_ASYNCH
175#define Curl_resolver_asynch() 1
176#else
177#define Curl_resolver_asynch() 0
178#endif
179
180
181/********** end of generic resolver interface functions *****************/
182#endif /* HEADER_CURL_ASYN_H */
183