--- c: Copyright (C) Daniel Stenberg, , et al. SPDX-License-Identifier: curl Title: CURLOPT_OPENSOCKETDATA Section: 3 Source: libcurl See-also: - CURLOPT_CLOSESOCKETFUNCTION (3) - CURLOPT_OPENSOCKETFUNCTION (3) - CURLOPT_SOCKOPTFUNCTION (3) --- # NAME CURLOPT_OPENSOCKETDATA - pointer passed to open socket callback # SYNOPSIS ~~~c #include CURLcode curl_easy_setopt(CURL *handle, CURLOPT_OPENSOCKETDATA, void *pointer); ~~~ # DESCRIPTION Pass a *pointer* that is untouched by libcurl and passed as the first argument in the open socket callback set with CURLOPT_OPENSOCKETFUNCTION(3). # DEFAULT The default value of this parameter is NULL. # PROTOCOLS All # EXAMPLE ~~~c /* make libcurl use the already established socket 'sockfd' */ static curl_socket_t opensocket(void *clientp, curlsocktype purpose, struct curl_sockaddr *address) { curl_socket_t sockfd; sockfd = *(curl_socket_t *)clientp; /* the actual externally set socket is passed in via the OPENSOCKETDATA option */ return sockfd; } static int sockopt_callback(void *clientp, curl_socket_t curlfd, curlsocktype purpose) { /* This return code was added in libcurl 7.21.5 */ return CURL_SOCKOPT_ALREADY_CONNECTED; } int main(void) { CURL *curl = curl_easy_init(); if(curl) { CURLcode res; extern int sockfd; /* the already connected one */ /* libcurl thinks that you connect to the host * and port that you specify in the URL option. */ curl_easy_setopt(curl, CURLOPT_URL, "http://99.99.99.99:9999"); /* call this function to get a socket */ curl_easy_setopt(curl, CURLOPT_OPENSOCKETFUNCTION, opensocket); curl_easy_setopt(curl, CURLOPT_OPENSOCKETDATA, &sockfd); /* call this function to set options for the socket */ curl_easy_setopt(curl, CURLOPT_SOCKOPTFUNCTION, sockopt_callback); res = curl_easy_perform(curl); curl_easy_cleanup(curl); } } ~~~ # AVAILABILITY Added in 7.17.1 # RETURN VALUE Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.