CURLOPT_OPENSOCKETFUNCTION(curl_easy_setopt optioCURLOPT_OPENSOCKETFUNCTION(3)NAMECURLOPT_OPENSOCKETFUNCTION - set callback for opening sockets
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;
struct curl_sockaddr {
int family;
int socktype;
int protocol;
unsigned int addrlen;
struct sockaddr addr;
};
curl_socket_t opensocket_callback(void *clientp,
curlsocktype purpose,
struct curl_sockaddr *address);
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_OPENSOCKETFUNCTION, opensocket_callback);
DESCRIPTION
Pass a pointer to your callback function, which should match the proto‐
type shown above.
This callback function gets called by libcurl instead of the socket(2)
call. The callback's purpose argument identifies the exact purpose for
this particular socket: CURLSOCKTYPE_IPCXN is for IP based connections
and CURLSOCKTYPE_ACCEPT is for sockets created after accept() - such as
when doing active FTP. Future versions of libcurl may support more pur‐
poses.
The clientp pointer contains whatever user-defined value set using the
CURLOPT_OPENSOCKETDATA(3) function.
The callback gets the resolved peer address as the address argument and
is allowed to modify the address or refuse to connect completely. The
callback function should return the newly created socket or
CURL_SOCKET_BAD in case no connection could be established or another
error was detected. Any additional setsockopt(2) calls can of course be
done on the socket at the user's discretion. A CURL_SOCKET_BAD return
value from the callback function will signal an unrecoverable error to
libcurl and it will return CURLE_COULDNT_CONNECT from the function that
triggered this callback. This return code can be used for IP address
blacklisting.
If you want to pass in a socket with an already established connection,
pass the socket back with this callback and then use CURLOPT_SOCKOPT‐
FUNCTION(3) to signal that it already is connected.
DEFAULT
The default behavior is the equivalent of this:
return socket(addr->family, addr->socktype, addr->protocol);
PROTOCOLS
All
EXAMPLEAVAILABILITY
Added in 7.17.1.
RETURN VALUE
Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION
if not.
SEE ALSOCURLOPT_OPENSOCKETDATA(3), CURLOPT_SOCKOPTFUNCTION(3), CURLOPT_CLOS‐
ESOCKETFUNCTION(3),
libcurl 7.37.0 16 Jun 2014 CURLOPT_OPENSOCKETFUNCTION(3)
