CURLMOPT_SOCKETDATA - custom pointer passed to the socket callback

Added in curl 7.15.4

NULL

A data pointer to pass to the socket callback set with the CURLMOPT_SOCKETFUNCTION(3) option. This pointer is not touched by libcurl but is only passed in as the socket callback's clientp argument.

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("my 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); }

CURLMOPT_SOCKETDATA - custom pointer passed to the socket callback

This functionality affects all supported protocols

Returns CURLM_OK.

CURLMOPT_SOCKETFUNCTION(3), CURLMOPT_TIMERFUNCTION(3), curl_multi_socket_action(3) libcurl 2025-06-16 CURLMOPT_SOCKETDATA(3)

#include <curl/curl.h> CURLMcode curl_multi_setopt(CURLM *handle, CURLMOPT_SOCKETDATA, void *pointer);