136 lines
3.4 KiB
Markdown
136 lines
3.4 KiB
Markdown
---
|
|
c: Copyright (C) Daniel Stenberg, <daniel.se>, et al.
|
|
SPDX-License-Identifier: curl
|
|
Title: CURLMOPT_SOCKETFUNCTION
|
|
Section: 3
|
|
Source: libcurl
|
|
See-also:
|
|
- CURLMOPT_SOCKETDATA (3)
|
|
- CURLMOPT_TIMERFUNCTION (3)
|
|
- curl_multi_socket_action (3)
|
|
---
|
|
|
|
# NAME
|
|
|
|
CURLMOPT_SOCKETFUNCTION - callback informed about what to wait for
|
|
|
|
# SYNOPSIS
|
|
|
|
~~~c
|
|
#include <curl/curl.h>
|
|
|
|
int socket_callback(CURL *easy, /* easy handle */
|
|
curl_socket_t s, /* socket */
|
|
int what, /* describes the socket */
|
|
void *clientp, /* private callback pointer */
|
|
void *socketp); /* private socket pointer */
|
|
|
|
CURLMcode curl_multi_setopt(CURLM *handle, CURLMOPT_SOCKETFUNCTION, socket_callback);
|
|
~~~
|
|
|
|
# DESCRIPTION
|
|
|
|
Pass a pointer to your callback function, which should match the prototype
|
|
shown above.
|
|
|
|
When the curl_multi_socket_action(3) function is called, it uses this
|
|
callback to inform the application about updates in the socket (file
|
|
descriptor) status by doing none, one, or multiple calls to the
|
|
**socket_callback**. The callback function gets status updates with changes
|
|
since the previous time the callback was called. If the given callback pointer
|
|
is set to NULL, no callback is called.
|
|
|
|
libcurl then expects the application to monitor the sockets for the specific
|
|
activities and tell libcurl again when something happens on one of them. Tell
|
|
libcurl by calling curl_multi_socket_action(3).
|
|
|
|
# CALLBACK ARGUMENTS
|
|
|
|
*easy* identifies the specific transfer for which this update is related.
|
|
|
|
*s* is the specific socket this function invocation concerns. If the
|
|
**what** argument is not CURL_POLL_REMOVE then it holds information about
|
|
what activity on this socket the application is supposed to
|
|
monitor. Subsequent calls to this callback might update the **what** bits
|
|
for a socket that is already monitored.
|
|
|
|
The socket callback should return 0 on success, and -1 on error. If this
|
|
callback returns error, **all** transfers currently in progress in this
|
|
multi handle are aborted and made to fail.
|
|
|
|
**clientp** is set with CURLMOPT_SOCKETDATA(3).
|
|
|
|
**socketp** is set with curl_multi_assign(3) or NULL.
|
|
|
|
The **what** parameter informs the callback on the status of the given
|
|
socket. It can hold one of these values:
|
|
|
|
## CURL_POLL_IN
|
|
|
|
Wait for incoming data. For the socket to become readable.
|
|
|
|
## CURL_POLL_OUT
|
|
|
|
Wait for outgoing data. For the socket to become writable.
|
|
|
|
## CURL_POLL_INOUT
|
|
|
|
Wait for incoming and outgoing data. For the socket to become readable or
|
|
writable.
|
|
|
|
## CURL_POLL_REMOVE
|
|
|
|
The specified socket/file descriptor is no longer used by libcurl for any
|
|
active transfer. It might soon be added again.
|
|
|
|
# DEFAULT
|
|
|
|
NULL (no callback)
|
|
|
|
# PROTOCOLS
|
|
|
|
All
|
|
|
|
# EXAMPLE
|
|
|
|
~~~c
|
|
struct priv {
|
|
void *ours;
|
|
};
|
|
|
|
static int sock_cb(CURL *e, curl_socket_t s, int what, void *cbp, void *sockp)
|
|
{
|
|
struct priv *p = sockp;
|
|
printf("our ptr: %p\n", p->ours);
|
|
|
|
if(what == CURL_POLL_REMOVE) {
|
|
/* remove the socket from our collection */
|
|
}
|
|
if(what & CURL_POLL_IN) {
|
|
/* wait for read on this socket */
|
|
}
|
|
if(what & CURL_POLL_OUT) {
|
|
/* wait for write on this socket */
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
int main(void)
|
|
{
|
|
struct priv setup;
|
|
CURLM *multi = curl_multi_init();
|
|
/* ... use socket callback and custom pointer */
|
|
curl_multi_setopt(multi, CURLMOPT_SOCKETFUNCTION, sock_cb);
|
|
curl_multi_setopt(multi, CURLMOPT_SOCKETDATA, &setup);
|
|
}
|
|
~~~
|
|
|
|
# AVAILABILITY
|
|
|
|
Added in 7.15.4
|
|
|
|
# RETURN VALUE
|
|
|
|
Returns CURLM_OK.
|