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* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
* Copyright (C) 1998 - 2019, Daniel Stenberg, <>, et al.
* This software is licensed as described in the file COPYING, which
* you should have received as part of this distribution. The terms
* are also available at
* You may opt to use, copy, modify, merge, publish, distribute and/or sell
* copies of the Software, and permit persons to whom the Software is
* furnished to do so, under the terms of the COPYING file.
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
#include "curl_setup.h"
#include "curl_addrinfo.h"
struct addrinfo;
struct hostent;
struct Curl_easy;
struct connectdata;
struct Curl_dns_entry;
* This header defines all functions in the internal asynch resolver interface.
* All asynch resolvers need to provide these functions.
* asyn-ares.c and asyn-thread.c are the current implementations of asynch
* resolver backends.
* Curl_resolver_global_init()
* Called from curl_global_init() to initialize global resolver environment.
* Returning anything else than CURLE_OK fails curl_global_init().
int Curl_resolver_global_init(void);
* Curl_resolver_global_cleanup()
* Called from curl_global_cleanup() to destroy global resolver environment.
void Curl_resolver_global_cleanup(void);
* Curl_resolver_init()
* Called from curl_easy_init() -> Curl_open() to initialize resolver
* URL-state specific environment ('resolver' member of the UrlState
* structure). Should fill the passed pointer by the initialized handler.
* Returning anything else than CURLE_OK fails curl_easy_init() with the
* correspondent code.
CURLcode Curl_resolver_init(struct Curl_easy *easy, void **resolver);
* Curl_resolver_cleanup()
* Called from curl_easy_cleanup() -> Curl_close() to cleanup resolver
* URL-state specific environment ('resolver' member of the UrlState
* structure). Should destroy the handler and free all resources connected to
* it.
void Curl_resolver_cleanup(void *resolver);
* Curl_resolver_duphandle()
* Called from curl_easy_duphandle() to duplicate resolver URL-state specific
* environment ('resolver' member of the UrlState structure). Should
* duplicate the 'from' handle and pass the resulting handle to the 'to'
* pointer. Returning anything else than CURLE_OK causes failed
* curl_easy_duphandle() call.
CURLcode Curl_resolver_duphandle(struct Curl_easy *easy, void **to,
void *from);
* Curl_resolver_cancel().
* It is called from inside other functions to cancel currently performing
* resolver request. Should also free any temporary resources allocated to
* perform a request. This never waits for resolver threads to complete.
* It is safe to call this when conn is in any state.
void Curl_resolver_cancel(struct connectdata *conn);
* Curl_resolver_kill().
* This acts like Curl_resolver_cancel() except it will block until any threads
* associated with the resolver are complete. This never blocks for resolvers
* that do not use threads. This is intended to be the "last chance" function
* that cleans up an in-progress resolver completely (before its owner is about
* to die).
* It is safe to call this when conn is in any state.
void Curl_resolver_kill(struct connectdata *conn);
/* Curl_resolver_getsock()
* This function is called from the multi_getsock() function. 'sock' is a
* pointer to an array to hold the file descriptors, with 'numsock' being the
* size of that array (in number of entries). This function is supposed to
* return bitmask indicating what file descriptors (referring to array indexes
* in the 'sock' array) to wait for, read/write.
int Curl_resolver_getsock(struct connectdata *conn, curl_socket_t *sock);
* Curl_resolver_is_resolved()
* Called repeatedly to check if a previous name resolve request has
* completed. It should also make sure to time-out if the operation seems to
* take too long.
* Returns normal CURLcode errors.
CURLcode Curl_resolver_is_resolved(struct connectdata *conn,
struct Curl_dns_entry **dns);
* Curl_resolver_wait_resolv()
* Waits for a resolve to finish. This function should be avoided since using
* this risk getting the multi interface to "hang".
* If 'entry' is non-NULL, make it point to the resolved dns entry
* Returns CURLE_COULDNT_RESOLVE_HOST if the host was not resolved,
* CURLE_OPERATION_TIMEDOUT if a time-out occurred, or other errors.
CURLcode Curl_resolver_wait_resolv(struct connectdata *conn,
struct Curl_dns_entry **dnsentry);
* Curl_resolver_getaddrinfo() - when using this resolver
* Returns name information about the given hostname and port number. If
* successful, the 'hostent' is returned and the forth argument will point to
* memory we need to free after use. That memory *MUST* be freed with
* Curl_freeaddrinfo(), nothing else.
* Each resolver backend must of course make sure to return data in the
* correct format to comply with this.
Curl_addrinfo *Curl_resolver_getaddrinfo(struct connectdata *conn,
const char *hostname,
int port,
int *waitp);
/* convert these functions if an asynch resolver isn't used */
#define Curl_resolver_cancel(x) Curl_nop_stmt
#define Curl_resolver_kill(x) Curl_nop_stmt
#define Curl_resolver_is_resolved(x,y) CURLE_COULDNT_RESOLVE_HOST
#define Curl_resolver_wait_resolv(x,y) CURLE_COULDNT_RESOLVE_HOST
#define Curl_resolver_getsock(x,y,z) 0
#define Curl_resolver_duphandle(x,y,z) CURLE_OK
#define Curl_resolver_init(x,y) CURLE_OK
#define Curl_resolver_global_init() CURLE_OK
#define Curl_resolver_global_cleanup() Curl_nop_stmt
#define Curl_resolver_cleanup(x) Curl_nop_stmt
#define Curl_resolver_asynch() 1
#define Curl_resolver_asynch() 0
/********** end of generic resolver interface functions *****************/
#endif /* HEADER_CURL_ASYN_H */