CURLOPT_SOCKOPTFUNCTION(3) curl_easy_setopt options CURLOPT_SOCKOPTFUNCTION(3)NAMECURLOPT_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 ALSOCURLOPT_SOCKOPTDATA(3), CURLOPT_OPENSOCKETFUNCTION(3),
libcurl 7.37.0 16 Jun 2014 CURLOPT_SOCKOPTFUNCTION(3)
