1 #ifndef HEADER_CURL_ASYN_H 2 #define HEADER_CURL_ASYN_H 3 /*************************************************************************** 4 * _ _ ____ _ 5 * Project ___| | | | _ \| | 6 * / __| | | | |_) | | 7 * | (__| |_| | _ <| |___ 8 * \___|\___/|_| \_\_____| 9 * 10 * Copyright (C) 1998 - 2019, 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 int numsocks); 119 120 /* 121 * Curl_resolver_is_resolved() 122 * 123 * Called repeatedly to check if a previous name resolve request has 124 * completed. It should also make sure to time-out if the operation seems to 125 * take too long. 126 * 127 * Returns normal CURLcode errors. 128 */ 129 CURLcode Curl_resolver_is_resolved(struct connectdata *conn, 130 struct Curl_dns_entry **dns); 131 132 /* 133 * Curl_resolver_wait_resolv() 134 * 135 * Waits for a resolve to finish. This function should be avoided since using 136 * this risk getting the multi interface to "hang". 137 * 138 * If 'entry' is non-NULL, make it point to the resolved dns entry 139 * 140 * Returns CURLE_COULDNT_RESOLVE_HOST if the host was not resolved, 141 * CURLE_OPERATION_TIMEDOUT if a time-out occurred, or other errors. 142 */ 143 CURLcode Curl_resolver_wait_resolv(struct connectdata *conn, 144 struct Curl_dns_entry **dnsentry); 145 146 /* 147 * Curl_resolver_getaddrinfo() - when using this resolver 148 * 149 * Returns name information about the given hostname and port number. If 150 * successful, the 'hostent' is returned and the forth argument will point to 151 * memory we need to free after use. That memory *MUST* be freed with 152 * Curl_freeaddrinfo(), nothing else. 153 * 154 * Each resolver backend must of course make sure to return data in the 155 * correct format to comply with this. 156 */ 157 Curl_addrinfo *Curl_resolver_getaddrinfo(struct connectdata *conn, 158 const char *hostname, 159 int port, 160 int *waitp); 161 162 #ifndef CURLRES_ASYNCH 163 /* convert these functions if an asynch resolver isn't used */ 164 #define Curl_resolver_cancel(x) Curl_nop_stmt 165 #define Curl_resolver_kill(x) Curl_nop_stmt 166 #define Curl_resolver_is_resolved(x,y) CURLE_COULDNT_RESOLVE_HOST 167 #define Curl_resolver_wait_resolv(x,y) CURLE_COULDNT_RESOLVE_HOST 168 #define Curl_resolver_getsock(x,y,z) 0 169 #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