CURLINFO_LASTSOCKET(3) - Man pages

CURLINFO_LASTSOCKET(3)      Library Functions Manual     CURLINFO_LASTSOCKET(3)

NAME
       CURLINFO_LASTSOCKET - get the last socket used

SYNOPSIS
       #include <curl/curl.h>

       CURLcode curl_easy_getinfo(CURL *handle, CURLINFO_LASTSOCKET, long *socket);

DESCRIPTION
       Deprecated since 7.45.0. Use CURLINFO_ACTIVESOCKET(3) instead.

       Pass  a  pointer  to a long to receive the last socket used by this curl
       session. If the socket is no longer valid, -1 is returned. When you fin-
       ish working with the socket, you must call curl_easy_cleanup(3) as usual
       and let libcurl close the socket and cleanup other resources  associated
       with the handle. This is typically used in combination with CURLOPT_CON-
       NECT_ONLY(3).

       NOTE:  this API is deprecated since it is not working on win64 where the
       SOCKET type is 64 bits large while  its  'long'  is  32  bits.  Use  the
       CURLINFO_ACTIVESOCKET(3) instead, if possible.

PROTOCOLS
       This functionality affects all supported protocols

EXAMPLE
       int main(void)
       {
         CURL *curl = curl_easy_init();
         if(curl) {
           CURLcode res;
           long sockfd; /* does not work on win64 */
           curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");

           /* Do not do the transfer - only connect to host */
           curl_easy_setopt(curl, CURLOPT_CONNECT_ONLY, 1L);
           res = curl_easy_perform(curl);
           if(res != CURLE_OK) {
             printf("Error: %s\n", curl_easy_strerror(res));
             curl_easy_cleanup(curl);
             return 1;
           }

           /* Extract the socket from the curl handle */
           res = curl_easy_getinfo(curl, CURLINFO_LASTSOCKET, &sockfd);
           if(!res && sockfd != -1) {
             /* operate on sockfd */
           }

           curl_easy_cleanup(curl);
         }
       }

AVAILABILITY
       Added in curl 7.15.2

RETURN VALUE
       curl_easy_getinfo(3) returns a CURLcode indicating success or error.

       CURLE_OK  (0) means everything was OK, non-zero means an error occurred,
       see libcurl-errors(3).

SEE ALSO
       CURLINFO_ACTIVESOCKET(3), CURLOPT_CONNECT_ONLY(3), curl_easy_getinfo(3),
       curl_easy_setopt(3)

libcurl                            2026-07-12            CURLINFO_LASTSOCKET(3)

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