curlopt_opensocketfunction(3) [mojave man page]

CURLOPT_OPENSOCKETFUNCTION(3)				     curl_easy_setopt options				     CURLOPT_OPENSOCKETFUNCTION(3)

NAME

       CURLOPT_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 prototype 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 purposes.

       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_SOCK-
       OPTFUNCTION(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

EXAMPLE

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_OPENSOCKETDATA(3), CURLOPT_SOCKOPTFUNCTION(3), CURLOPT_CLOSESOCKETFUNCTION(3),

libcurl 7.54.0							 February 03, 2016				     CURLOPT_OPENSOCKETFUNCTION(3)

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 prototype 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 identifies 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_SOCKOPT_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_SOCK-
       OPT_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 CURLOPT_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)