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#ifndef __CURL_MULTI_H
#define __CURL_MULTI_H
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
* Copyright (C) 1998 - 2015, Daniel Stenberg, <daniel@haxx.se>, 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 https://curl.haxx.se/docs/copyright.html.
* 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.
This is an "external" header file. Don't give away any internals here!
o Enable a "pull" interface. The application that uses libcurl decides where
and when to ask libcurl to get/send data.
o Enable multiple simultaneous transfers in the same thread without making it
complicated for the application.
o Enable the application to select() on its own file descriptors and curl's
file descriptors simultaneous easily.
* This header file should not really need to include "curl.h" since curl.h
* itself includes this file and we expect user applications to do #include
* <curl/curl.h> without the need for especially including multi.h.
* For some reason we added this include here at one point, and rather than to
* break existing (wrongly written) libcurl applications, we leave it as-is
* but with this warning attached.
#include "curl.h"
#ifdef __cplusplus
extern "C" {
typedef void CURLM;
typedef enum {
CURLM_CALL_MULTI_PERFORM = -1, /* please call curl_multi_perform() or
curl_multi_socket*() soon */
CURLM_BAD_HANDLE, /* the passed-in handle is not a valid CURLM handle */
CURLM_BAD_EASY_HANDLE, /* an easy handle was not good/valid */
CURLM_OUT_OF_MEMORY, /* if you ever get this, you're in deep sh*t */
CURLM_INTERNAL_ERROR, /* this is a libcurl bug */
CURLM_BAD_SOCKET, /* the passed in socket argument did not match */
CURLM_UNKNOWN_OPTION, /* curl_multi_setopt() with unsupported option */
CURLM_ADDED_ALREADY, /* an easy handle already added to a multi handle was
attempted to get added - again */
} CURLMcode;
/* just to make code nicer when using curl_multi_socket() you can now check
for CURLM_CALL_MULTI_SOCKET too in the same style it works for
curl_multi_perform() and CURLM_CALL_MULTI_PERFORM */
/* bitmask bits for CURLMOPT_PIPELINING */
typedef enum {
CURLMSG_NONE, /* first, not used */
CURLMSG_DONE, /* This easy handle has completed. 'result' contains
the CURLcode of the transfer */
CURLMSG_LAST /* last, not used */
struct CURLMsg {
CURLMSG msg; /* what this message means */
CURL *easy_handle; /* the handle it concerns */
union {
void *whatever; /* message-specific data */
CURLcode result; /* return code for transfer */
} data;
typedef struct CURLMsg CURLMsg;
/* Based on poll(2) structure and values.
* We don't use pollfd and POLL* constants explicitly
* to cover platforms without poll(). */
#define CURL_WAIT_POLLIN 0x0001
#define CURL_WAIT_POLLPRI 0x0002
#define CURL_WAIT_POLLOUT 0x0004
struct curl_waitfd {
curl_socket_t fd;
short events;
short revents; /* not supported yet */
* Name: curl_multi_init()
* Desc: inititalize multi-style curl usage
* Returns: a new CURLM handle to use in all 'curl_multi' functions.
CURL_EXTERN CURLM *curl_multi_init(void);
* Name: curl_multi_add_handle()
* Desc: add a standard curl handle to the multi stack
* Returns: CURLMcode type, general multi error code.
CURL_EXTERN CURLMcode curl_multi_add_handle(CURLM *multi_handle,
CURL *curl_handle);
* Name: curl_multi_remove_handle()
* Desc: removes a curl handle from the multi stack again
* Returns: CURLMcode type, general multi error code.
CURL_EXTERN CURLMcode curl_multi_remove_handle(CURLM *multi_handle,
CURL *curl_handle);
* Name: curl_multi_fdset()
* Desc: Ask curl for its fd_set sets. The app can use these to select() or
* poll() on. We want curl_multi_perform() called as soon as one of
* them are ready.
* Returns: CURLMcode type, general multi error code.
CURL_EXTERN CURLMcode curl_multi_fdset(CURLM *multi_handle,
fd_set *read_fd_set,
fd_set *write_fd_set,
fd_set *exc_fd_set,
int *max_fd);
* Name: curl_multi_wait()
* Desc: Poll on all fds within a CURLM set as well as any
* additional fds passed to the function.
* Returns: CURLMcode type, general multi error code.
CURL_EXTERN CURLMcode curl_multi_wait(CURLM *multi_handle,
struct curl_waitfd extra_fds[],
unsigned int extra_nfds,
int timeout_ms,
int *ret);
* Name: curl_multi_perform()
* Desc: When the app thinks there's data available for curl it calls this
* function to read/write whatever there is right now. This returns
* as soon as the reads and writes are done. This function does not
* require that there actually is data available for reading or that
* data can be written, it can be called just in case. It returns
* the number of handles that still transfer data in the second
* argument's integer-pointer.
* Returns: CURLMcode type, general multi error code. *NOTE* that this only
* returns errors etc regarding the whole multi stack. There might
* still have occurred problems on invidual transfers even when this
* returns OK.
CURL_EXTERN CURLMcode curl_multi_perform(CURLM *multi_handle,
int *running_handles);
* Name: curl_multi_cleanup()
* Desc: Cleans up and removes a whole multi stack. It does not free or
* touch any individual easy handles in any way. We need to define
* in what state those handles will be if this function is called
* in the middle of a transfer.
* Returns: CURLMcode type, general multi error code.
CURL_EXTERN CURLMcode curl_multi_cleanup(CURLM *multi_handle);
* Name: curl_multi_info_read()
* Desc: Ask the multi handle if there's any messages/informationals from
* the individual transfers. Messages include informationals such as
* error code from the transfer or just the fact that a transfer is
* completed. More details on these should be written down as well.
* Repeated calls to this function will return a new struct each
* time, until a special "end of msgs" struct is returned as a signal
* that there is no more to get at this point.
* The data the returned pointer points to will not survive calling
* curl_multi_cleanup().
* The 'CURLMsg' struct is meant to be very simple and only contain
* very basic informations. If more involved information is wanted,
* we will provide the particular "transfer handle" in that struct
* and that should/could/would be used in subsequent
* curl_easy_getinfo() calls (or similar). The point being that we
* must never expose complex structs to applications, as then we'll
* undoubtably get backwards compatibility problems in the future.
* Returns: A pointer to a filled-in struct, or NULL if it failed or ran out
* of structs. It also writes the number of messages left in the
* queue (after this read) in the integer the second argument points
* to.
CURL_EXTERN CURLMsg *curl_multi_info_read(CURLM *multi_handle,
int *msgs_in_queue);
* Name: curl_multi_strerror()
* Desc: The curl_multi_strerror function may be used to turn a CURLMcode
* value into the equivalent human readable error string. This is
* useful for printing meaningful error messages.
* Returns: A pointer to a zero-terminated error message.
CURL_EXTERN const char *curl_multi_strerror(CURLMcode);
* Name: curl_multi_socket() and
* curl_multi_socket_all()
* Desc: An alternative version of curl_multi_perform() that allows the
* application to pass in one of the file descriptors that have been
* detected to have "action" on them and let libcurl perform.
* See man page for details.
#define CURL_POLL_NONE 0
#define CURL_POLL_IN 1
#define CURL_POLL_OUT 2
#define CURL_CSELECT_IN 0x01
#define CURL_CSELECT_OUT 0x02
#define CURL_CSELECT_ERR 0x04
typedef int (*curl_socket_callback)(CURL *easy, /* easy handle */
curl_socket_t s, /* socket */
int what, /* see above */
void *userp, /* private callback
pointer */
void *socketp); /* private socket
pointer */
* Name: curl_multi_timer_callback
* Desc: Called by libcurl whenever the library detects a change in the
* maximum number of milliseconds the app is allowed to wait before
* curl_multi_socket() or curl_multi_perform() must be called
* (to allow libcurl's timed events to take place).
* Returns: The callback should return zero.
typedef int (*curl_multi_timer_callback)(CURLM *multi, /* multi handle */
long timeout_ms, /* see above */
void *userp); /* private callback
pointer */
CURL_EXTERN CURLMcode curl_multi_socket(CURLM *multi_handle, curl_socket_t s,
int *running_handles);
CURL_EXTERN CURLMcode curl_multi_socket_action(CURLM *multi_handle,
curl_socket_t s,
int ev_bitmask,
int *running_handles);
CURL_EXTERN CURLMcode curl_multi_socket_all(CURLM *multi_handle,
int *running_handles);
/* This macro below was added in 7.16.3 to push users who recompile to use
the new curl_multi_socket_action() instead of the old curl_multi_socket()
#define curl_multi_socket(x,y,z) curl_multi_socket_action(x,y,0,z)
* Name: curl_multi_timeout()
* Desc: Returns the maximum number of milliseconds the app is allowed to
* wait before curl_multi_socket() or curl_multi_perform() must be
* called (to allow libcurl's timed events to take place).
* Returns: CURLM error code.
CURL_EXTERN CURLMcode curl_multi_timeout(CURLM *multi_handle,
long *milliseconds);
#undef CINIT /* re-using the same name as in curl.h */
#define CINIT(name,type,num) CURLMOPT_ ## name = CURLOPTTYPE_ ## type + num
/* The macro "##" is ISO C, we assume pre-ISO C doesn't support it. */
#define CINIT(name,type,number) CURLMOPT_/**/name = type + number
typedef enum {
/* This is the socket callback function pointer */
/* This is the argument passed to the socket callback */
/* set to 1 to enable pipelining for this multi handle */
/* This is the timer callback function pointer */
/* This is the argument passed to the timer callback */
/* maximum number of entries in the connection cache */
/* maximum number of (pipelining) connections to one host */
/* maximum number of requests in a pipeline */
/* a connection with a content-length longer than this
will not be considered for pipelining */
/* a connection with a chunk length longer than this
will not be considered for pipelining */
/* a list of site names(+port) that are blacklisted from
pipelining */
/* a list of server types that are blacklisted from
pipelining */
/* maximum number of open connections in total */
/* This is the server push callback function pointer */
/* This is the argument passed to the server push callback */
CURLMOPT_LASTENTRY /* the last unused */
} CURLMoption;
* Name: curl_multi_setopt()
* Desc: Sets options for the multi handle.
* Returns: CURLM error code.
CURL_EXTERN CURLMcode curl_multi_setopt(CURLM *multi_handle,
CURLMoption option, ...);
* Name: curl_multi_assign()
* Desc: This function sets an association in the multi handle between the
* given socket and a private pointer of the application. This is
* (only) useful for curl_multi_socket uses.
* Returns: CURLM error code.
CURL_EXTERN CURLMcode curl_multi_assign(CURLM *multi_handle,
curl_socket_t sockfd, void *sockp);
* Name: curl_push_callback
* Desc: This callback gets called when a new stream is being pushed by the
* server. It approves or denies the new stream.
#define CURL_PUSH_OK 0
#define CURL_PUSH_DENY 1
struct curl_pushheaders; /* forward declaration only */
CURL_EXTERN char *curl_pushheader_bynum(struct curl_pushheaders *h,
size_t num);
CURL_EXTERN char *curl_pushheader_byname(struct curl_pushheaders *h,
const char *name);
typedef int (*curl_push_callback)(CURL *parent,
CURL *easy,
size_t num_headers,
struct curl_pushheaders *headers,
void *userp);
#ifdef __cplusplus
} /* end of extern "C" */