Provided by: libcurl4-doc_7.58.0-2ubuntu3.24_all bug


       CURLOPT_CONNECT_TO  -  Connect  to  a specific host and port instead of the URL's host and


       #include <curl/curl.h>

       CURLcode curl_easy_setopt(CURL *handle, CURLOPT_CONNECT_TO,
                                 struct curl_slist *connect_to);


       Pass a pointer to a linked list of strings  with  "connect  to"  information  to  use  for
       establishing network connections with this handle. The linked list should be a fully valid
       list of struct curl_slist structs properly filled in. Use curl_slist_append(3)  to  create
       the list and curl_slist_free_all(3) to clean up an entire list.

       Each  single  string should be written using the format HOST:PORT:CONNECT-TO-HOST:CONNECT-
       TO-PORT where HOST is the host of the request, PORT is the port of the  request,  CONNECT-
       TO-HOST is the host name to connect to, and CONNECT-TO-PORT is the port to connect to.

       The first string that matches the request's host and port is used.

       Dotted  numerical  IP  addresses  are supported for HOST and CONNECT-TO-HOST.  A numerical
       IPv6 address must be written within [brackets].

       Any of the four values may be empty. When the HOST or PORT is empty, the host or port will
       always match (the request's host or port is ignored).  When CONNECT-TO-HOST or CONNECT-TO-
       PORT is empty, the "connect to" feature will be disabled for the host  or  port,  and  the
       request's host or port will be used to establish the network connection.

       This  option  is  suitable  to direct the request at a specific server, e.g. at a specific
       cluster node in a cluster of servers.

       The "connect to" host and port are only used to establish the network connection. They  do
       NOT  affect  the  host  and  port  that  are  used  for  TLS/SSL  (e.g.  SNI,  certificate
       verification) or for the application protocols.

       In contrast to CURLOPT_RESOLVE(3), the option CURLOPT_CONNECT_TO(3) does not  pre-populate
       the DNS cache and therefore it does not affect future transfers of other easy handles that
       have been added to the same multi handle.

       The "connect to" host and port are ignored if they are equal to the host and the  port  in
       the  request  URL,  because  connecting to the host and the port in the request URL is the
       default behavior.

       If an HTTP proxy is used for a request having a special "connect to" host or port, and the
       "connect  to"  host  or  port differs from the requests's host and port, the HTTP proxy is
       automatically switched to tunnel mode for this specific request. This is necessary because
       it is not possible to connect to a specific host or port in normal (non-tunnel) mode.

       When  this  option is passed to curl_easy_setopt(3), libcurl will not copy the entire list
       so you must keep it around until you no longer use this handle for a transfer  before  you
       call curl_slist_free_all(3) on the list.






       CURL *curl;
       struct curl_slist *connect_to = NULL;
       connect_to = curl_slist_append(NULL, "");

       curl = curl_easy_init();
       if(curl) {
         curl_easy_setopt(curl, CURLOPT_CONNECT_TO, connect_to);
         curl_easy_setopt(curl, CURLOPT_URL, "");


         /* always cleanup */



       Added in 7.49.0


       Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.