.\" generated by cd2nroff 0.1 from CURLOPT_OPENSOCKETDATA.md .TH CURLOPT_OPENSOCKETDATA 3 "2024-06-01" libcurl .SH NAME CURLOPT_OPENSOCKETDATA \- pointer passed to open socket callback .SH SYNOPSIS .nf #include CURLcode curl_easy_setopt(CURL *handle, CURLOPT_OPENSOCKETDATA, void *pointer); .fi .SH DESCRIPTION Pass a \fIpointer\fP that is untouched by libcurl and passed as the first argument in the open socket callback set with \fICURLOPT_OPENSOCKETFUNCTION(3)\fP. .SH DEFAULT The default value of this parameter is NULL. .SH PROTOCOLS All .SH EXAMPLE .nf /* 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); } } .fi .SH AVAILABILITY Added in 7.17.1 .SH RETURN VALUE Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not. .SH SEE ALSO .BR CURLOPT_CLOSESOCKETFUNCTION (3), .BR CURLOPT_OPENSOCKETFUNCTION (3), .BR CURLOPT_SOCKOPTFUNCTION (3)