**************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) 1998 - 2017, 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.
*
**************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) 1998 - 2017, 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.
*
**************************************************************************
CURLMOPT_SOCKETFUNCTION 3 "September 23, 2018" "libcurl 7.64.1" "curl_multi_setopt options"
NAME
CURLMOPT_SOCKETFUNCTION - callback informed about what to wait for
SYNOPSIS
#include <curl/curl.h> int socket_callback(CURL *easy, /* easy handle */ curl_socket_t s, /* socket */ int what, /* describes the socket */ void *userp, /* private callback pointer */ void *socketp); /* private socket pointer */ CURLMcode curl_multi_setopt(CURLM *handle, CURLMOPT_SOCKETFUNCTION, socket_callback);DESCRIPTIONPass a pointer to your callback function, which should match the prototype shown above. When the curl_multi_socket_action(3) function runs, it informs the application about updates in the socket (file descriptor) status by doing none, one, or multiple calls to the socket_callback. The callback gets status updates with changes since the previous time the callback was called. If the given callback pointer is NULL, no callback will be called. Set the callback's userp argument with CURLMOPT_SOCKETDATA(3). See curl_multi_socket_action(3) for more details on how the callback is used and should work. The what parameter informs the callback on the status of the given socket. It can hold one of these values:CURL_POLL_INWait for incoming data. For the socket to become readable.CURL_POLL_OUTWait for outgoing data. For the socket to become writable.CURL_POLL_INOUTWait for incoming and outgoing data. For the socket to become readable or writable.CURL_POLL_REMOVEThe specified socket/file descriptor is no longer used by libcurl.DEFAULTNULL (no callback)PROTOCOLSAllEXAMPLEstatic int sock_cb(CURL *e, curl_socket_t s, int what, void *cbp, void *sockp) { GlobalInfo *g = (GlobalInfo*) cbp; SockInfo *fdp = (SockInfo*) sockp; if(what == CURL_POLL_REMOVE) { remsock(fdp); } else { if(!fdp) { addsock(s, e, what, g); } else { setsock(fdp, s, e, what, g); } } return 0; } main() { GlobalInfo setup; /* ... use socket callback and custom pointer */ curl_multi_setopt(multi, CURLMOPT_SOCKETFUNCTION, sock_cb); curl_multi_setopt(multi, CURLMOPT_SOCKETDATA, &setup); }AVAILABILITYAdded in 7.15.4RETURN VALUEReturns CURLM_OK."SEE ALSO"CURLMOPT_SOCKETDATA "(3), " curl_multi_socket_action "(3), " CURLMOPT_TIMERFUNCTION "(3) "