1 #ifndef HEADER_CURL_ASYN_H
2 #define HEADER_CURL_ASYN_H
3 /***************************************************************************
4  *                                  _   _ ____  _
5  *  Project                     ___| | | |  _ \| |
6  *                             / __| | | | |_) | |
7  *                            | (__| |_| |  _ <| |___
8  *                             \___|\___/|_| \_\_____|
9  *
10  * Copyright (C) 1998 - 2020, 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.haxx.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 
28 struct addrinfo;
29 struct hostent;
30 struct Curl_easy;
31 struct connectdata;
32 struct 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  */
47 int Curl_resolver_global_init(void);
48 
49 /*
50  * Curl_resolver_global_cleanup()
51  * Called from curl_global_cleanup() to destroy global resolver environment.
52  */
53 void 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  */
63 CURLcode 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  */
72 void 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  */
82 CURLcode 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  */
94 void Curl_resolver_cancel(struct connectdata *conn);
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  */
107 void Curl_resolver_kill(struct connectdata *conn);
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  */
117 int Curl_resolver_getsock(struct connectdata *conn, 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  */
128 CURLcode Curl_resolver_is_resolved(struct connectdata *conn,
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  */
142 CURLcode Curl_resolver_wait_resolv(struct connectdata *conn,
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  */
156 struct Curl_addrinfo *Curl_resolver_getaddrinfo(struct connectdata *conn,
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_getsock(x,y,z) 0
168 #define Curl_resolver_duphandle(x,y,z) CURLE_OK
169 #define Curl_resolver_init(x,y) CURLE_OK
170 #define Curl_resolver_global_init() CURLE_OK
171 #define Curl_resolver_global_cleanup() Curl_nop_stmt
172 #define Curl_resolver_cleanup(x) Curl_nop_stmt
173 #endif
174 
175 #ifdef CURLRES_ASYNCH
176 #define Curl_resolver_asynch() 1
177 #else
178 #define Curl_resolver_asynch() 0
179 #endif
180 
181 
182 /********** end of generic resolver interface functions *****************/
183 #endif /* HEADER_CURL_ASYN_H */
184