CURLOPT_SOCKOPTFUNCTION(3) curl_easy_setopt options CURLOPT_SOCKOPTFUNCTION(3)

NAME
       CURLOPT_SOCKOPTFUNCTION - set callback for setting socket options

SYNOPSIS
       #include <curl/curl.h>

       typedef enum  {
         CURLSOCKTYPE_IPCXN,  /* socket created for a specific IP connection */
         CURLSOCKTYPE_ACCEPT, /* socket created by accept() call */
         CURLSOCKTYPE_LAST    /* never use */
       } curlsocktype;

       #define CURL_SOCKOPT_OK 0
       #define CURL_SOCKOPT_ERROR 1 /* causes libcurl to abort and return
                                       CURLE_ABORTED_BY_CALLBACK */
       #define CURL_SOCKOPT_ALREADY_CONNECTED 2

       int sockopt_callback(void *clientp,
                            curl_socket_t curlfd,
                            curlsocktype purpose);

       CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SOCKOPTFUNCTION, sockopt_callback);

DESCRIPTION
       Pass a pointer to your callback function, which should match the proto-
       type shown above.

       When set, this callback function gets called by libcurl when the socket
       has  been created, but before the connect call to allow applications to
       change specific socket options. The callback's purpose argument identi-
       fies the exact purpose for this particular socket:

       CURLSOCKTYPE_IPCXN  for  actively  created  connections or since 7.28.0
       CURLSOCKTYPE_ACCEPT  for  FTP  when  the  connection  was  setup   with
       PORT/EPSV  (in  earlier  versions  these sockets weren't passed to this
       callback).

       Future versions of libcurl may support more  purposes.  libcurl  passes
       the  newly  created  socket  descriptor  to  the callback in the curlfd
       parameter so additional setsockopt() calls can be done  at  the  user's
       discretion.

       The  clientp pointer contains whatever user-defined value set using the
       CURLOPT_SOCKOPTDATA(3) function.

       Return CURL_SOCKOPT_OK from the callback on success. Return  CURL_SOCK-
       OPT_ERROR  from  the callback function to signal an unrecoverable error
       to  the  library  and   it   will   close   the   socket   and   return
       CURLE_COULDNT_CONNECT.  Alternatively, the callback function can return
       CURL_SOCKOPT_ALREADY_CONNECTED, to tell  libcurl  that  the  socket  is
       already connected and then libcurl will not attempt to connect it. This
       allows an application to pass in an already connected socket with  CUR-
       LOPT_OPENSOCKETFUNCTION(3) and then have this function make libcurl not
       attempt to connect (again).

DEFAULT
       By default, this callback is NULL and unused.

PROTOCOLS
       All

EXAMPLE
       TODO

AVAILABILITY
       Added in 7.16.0. The  CURL_SOCKOPT_ALREADY_CONNECTED  return  code  was
       added in 7.21.5.

RETURN VALUE
       Returns  CURLE_OK  if the option is supported, and CURLE_UNKNOWN_OPTION
       if not.

SEE ALSO
       CURLOPT_SOCKOPTDATA(3), CURLOPT_OPENSOCKETFUNCTION(3),

libcurl 7.54.0                 February 03, 2016    CURLOPT_SOCKOPTFUNCTION(3)