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)

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curl_multi_assign(3)						  libcurl Manual					      curl_multi_assign(3)

NAME

       curl_multi_assign - set data to association 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 assigns an association in the multi handle between the given socket and a private pointer of the application. This is (only)
       useful for curl_multi_socket(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(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, although not deemed stable yet.

SEE ALSO

       curl_multi_setopt(3), curl_multi_socket(3)

libcurl 7.16.0							    9 Jul 2006						      curl_multi_assign(3)

Linux and UNIX Man Pages

curlopt_opensocketfunction(3) [mojave man page]

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