curlopt_sockoptfunction(3) [mojave man page]

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)

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curl_multi_assign(3)						  libcurl Manual					      curl_multi_assign(3)

NAME

       curl_multi_assign - set data to associate with an internal socket

SYNOPSIS

       #include <curl/curl.h>

       CURLMcode curl_multi_assign(CURLM *multi_handle, curl_socket_t sockfd,
				   void *sockptr);

DESCRIPTION

       This  function  creates	an  association  in  the  multi  handle between the given socket and a private pointer of the application. This is
       designed for curl_multi_socket_action(3) uses.

       When set, the sockptr pointer will be passed to all future socket callbacks for the specific sockfd socket.

       If the given sockfd isn't already in use by libcurl, this function will return an error.

       libcurl only keeps one single pointer associated with a socket, so calling this function several times for the same socket  will  make  the
       last set pointer get used.

       The  idea  here	being  that this association (socket to private pointer) is something that just about every application that uses this API
       will need and then libcurl can just as well do it since it already has an internal hash table lookup for this.

RETURN VALUE

       The standard CURLMcode for multi interface error codes.

TYPICAL USAGE

       In a typical application you allocate a struct or at least use some kind of semi-dynamic data for each socket that we must wait for  action
       on when using the curl_multi_socket_action(3) approach.

       When our socket-callback gets called by libcurl and we get to know about yet another socket to wait for, we can use curl_multi_assign(3) to
       point out the particular data so that when we get updates about this same socket again, we don't have to find the  struct  associated  with
       this socket by ourselves.

AVAILABILITY

       This function was added in libcurl 7.15.5.

SEE ALSO

       curl_multi_setopt(3), curl_multi_socket_action(3)

libcurl 7.54.0							 February 03, 2016					      curl_multi_assign(3)

Linux and UNIX Man Pages

curlopt_sockoptfunction(3) [mojave man page]

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