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CURLOPT_OPENSOCKETDATA(3)           libcurl          CURLOPT_OPENSOCKETDATA(3)

NAME
       CURLOPT_OPENSOCKETDATA - pointer passed to open socket callback

SYNOPSIS
       #include <curl/curl.h>

       CURLcode curl_easy_setopt(CURL *handle, CURLOPT_OPENSOCKETDATA, void *pointer);

DESCRIPTION
       Pass a pointer that will be 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
       /* 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;
       }

       curl = curl_easy_init();
       if(curl) {
         /* libcurl will internally think 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.

SEE ALSO
       CURLOPT_OPENSOCKETFUNCTION(3), CURLOPT_SOCKOPTFUNCTION(3),

ibcurl 8.1.2                    April 26, 2023       CURLOPT_OPENSOCKETDATA(3)