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      1 #ifndef HEADER_CURL_ASYN_H
      2 #define HEADER_CURL_ASYN_H
      3 /***************************************************************************
      4  *                                  _   _ ____  _
      5  *  Project                     ___| | | |  _ \| |
      6  *                             / __| | | | |_) | |
      7  *                            | (__| |_| |  _ <| |___
      8  *                             \___|\___/|_| \_\_____|
      9  *
     10  * Copyright (C) 1998 - 2011, Daniel Stenberg, <daniel (at) 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 http://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 SessionHandle;
     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(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 int Curl_resolver_duphandle(void **to, void *from);
     83 
     84 /*
     85  * Curl_resolver_cancel().
     86  *
     87  * It is called from inside other functions to cancel currently performing
     88  * resolver request. Should also free any temporary resources allocated to
     89  * perform a request.
     90  */
     91 void Curl_resolver_cancel(struct connectdata *conn);
     92 
     93 /* Curl_resolver_getsock()
     94  *
     95  * This function is called from the multi_getsock() function.  'sock' is a
     96  * pointer to an array to hold the file descriptors, with 'numsock' being the
     97  * size of that array (in number of entries). This function is supposed to
     98  * return bitmask indicating what file descriptors (referring to array indexes
     99  * in the 'sock' array) to wait for, read/write.
    100  */
    101 int Curl_resolver_getsock(struct connectdata *conn, curl_socket_t *sock,
    102                           int numsocks);
    103 
    104 /*
    105  * Curl_resolver_is_resolved()
    106  *
    107  * Called repeatedly to check if a previous name resolve request has
    108  * completed. It should also make sure to time-out if the operation seems to
    109  * take too long.
    110  *
    111  * Returns normal CURLcode errors.
    112  */
    113 CURLcode Curl_resolver_is_resolved(struct connectdata *conn,
    114                                    struct Curl_dns_entry **dns);
    115 
    116 /*
    117  * Curl_resolver_wait_resolv()
    118  *
    119  * waits for a resolve to finish. This function should be avoided since using
    120  * this risk getting the multi interface to "hang".
    121  *
    122  * If 'entry' is non-NULL, make it point to the resolved dns entry
    123  *
    124  * Returns CURLE_COULDNT_RESOLVE_HOST if the host was not resolved, and
    125  * CURLE_OPERATION_TIMEDOUT if a time-out occurred.
    126 
    127  */
    128 CURLcode Curl_resolver_wait_resolv(struct connectdata *conn,
    129                                    struct Curl_dns_entry **dnsentry);
    130 
    131 /*
    132  * Curl_resolver_getaddrinfo() - when using this resolver
    133  *
    134  * Returns name information about the given hostname and port number. If
    135  * successful, the 'hostent' is returned and the forth argument will point to
    136  * memory we need to free after use. That memory *MUST* be freed with
    137  * Curl_freeaddrinfo(), nothing else.
    138  *
    139  * Each resolver backend must of course make sure to return data in the
    140  * correct format to comply with this.
    141  */
    142 Curl_addrinfo *Curl_resolver_getaddrinfo(struct connectdata *conn,
    143                                          const char *hostname,
    144                                          int port,
    145                                          int *waitp);
    146 
    147 #ifndef CURLRES_ASYNCH
    148 /* convert these functions if an asynch resolver isn't used */
    149 #define Curl_resolver_cancel(x) Curl_nop_stmt
    150 #define Curl_resolver_is_resolved(x,y) CURLE_COULDNT_RESOLVE_HOST
    151 #define Curl_resolver_wait_resolv(x,y) CURLE_COULDNT_RESOLVE_HOST
    152 #define Curl_resolver_getsock(x,y,z) 0
    153 #define Curl_resolver_duphandle(x,y) CURLE_OK
    154 #define Curl_resolver_init(x) CURLE_OK
    155 #define Curl_resolver_global_init() CURLE_OK
    156 #define Curl_resolver_global_cleanup() Curl_nop_stmt
    157 #define Curl_resolver_cleanup(x) Curl_nop_stmt
    158 #endif
    159 
    160 #ifdef CURLRES_ASYNCH
    161 #define Curl_resolver_asynch() 1
    162 #else
    163 #define Curl_resolver_asynch() 0
    164 #endif
    165 
    166 
    167 /********** end of generic resolver interface functions *****************/
    168 #endif /* HEADER_CURL_ASYN_H */
    169