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                     23: .TH CURLOPT_CONNECT_TO 3 "March 23, 2020" "libcurl 7.70.0" "curl_easy_setopt options"
                     24: 
                     25: .SH NAME
                     26: CURLOPT_CONNECT_TO \- Connect to a specific host and port instead of the URL's host and port
                     27: .SH SYNOPSIS
                     28: .nf
                     29: #include <curl/curl.h>
                     30: 
                     31: CURLcode curl_easy_setopt(CURL *handle, CURLOPT_CONNECT_TO,
                     32:                           struct curl_slist *connect_to);
                     33: .fi
                     34: .SH DESCRIPTION
                     35: Pass a pointer to a linked list of strings with "connect to" information to
                     36: use for establishing network connections with this handle. The linked list
                     37: should be a fully valid list of \fBstruct curl_slist\fP structs properly
                     38: filled in. Use \fIcurl_slist_append(3)\fP to create the list and
                     39: \fIcurl_slist_free_all(3)\fP to clean up an entire list.
                     40: 
                     41: Each single string should be written using the format
                     42: HOST:PORT:CONNECT-TO-HOST:CONNECT-TO-PORT where HOST is the host of the
                     43: request, PORT is the port of the request, CONNECT-TO-HOST is the host name to
                     44: connect to, and CONNECT-TO-PORT is the port to connect to.
                     45: 
                     46: The first string that matches the request's host and port is used.
                     47: 
                     48: Dotted numerical IP addresses are supported for HOST and CONNECT-TO-HOST.
                     49: A numerical IPv6 address must be written within [brackets].
                     50: 
                     51: Any of the four values may be empty. When the HOST or PORT is empty, the host
                     52: or port will always match (the request's host or port is ignored).
                     53: When CONNECT-TO-HOST or CONNECT-TO-PORT is empty, the "connect to" feature
                     54: will be disabled for the host or port, and the request's host or port will be
                     55: used to establish the network connection.
                     56: 
                     57: This option is suitable to direct the request at a specific server, e.g. at a
                     58: specific cluster node in a cluster of servers.
                     59: 
                     60: The "connect to" host and port are only used to establish the network
                     61: connection. They do NOT affect the host and port that are used for TLS/SSL
                     62: (e.g. SNI, certificate verification) or for the application protocols.
                     63: 
                     64: In contrast to \fICURLOPT_RESOLVE(3)\fP, the option
                     65: \fICURLOPT_CONNECT_TO(3)\fP does not pre-populate the DNS cache and therefore
                     66: it does not affect future transfers of other easy handles that have been added
                     67: to the same multi handle.
                     68: 
                     69: The "connect to" host and port are ignored if they are equal to the host and
                     70: the port in the request URL, because connecting to the host and the port in
                     71: the request URL is the default behavior.
                     72: 
                     73: If an HTTP proxy is used for a request having a special "connect to" host or
                     74: port, and the "connect to" host or port differs from the request's host and
                     75: port, the HTTP proxy is automatically switched to tunnel mode for this
                     76: specific request. This is necessary because it is not possible to connect to a
                     77: specific host or port in normal (non-tunnel) mode.
                     78: 
                     79: When this option is passed to \fIcurl_easy_setopt(3)\fP, libcurl will not copy
                     80: the entire list so you \fBmust\fP keep it around until you no longer use this
                     81: \fIhandle\fP for a transfer before you call \fIcurl_slist_free_all(3)\fP on
                     82: the list.
                     83: 
                     84: .SH DEFAULT
                     85: NULL
                     86: .SH PROTOCOLS
                     87: All
                     88: .SH EXAMPLE
                     89: .nf
                     90: CURL *curl;
                     91: struct curl_slist *connect_to = NULL;
                     92: connect_to = curl_slist_append(NULL, "example.com::server1.example.com:");
                     93: 
                     94: curl = curl_easy_init();
                     95: if(curl) {
                     96:   curl_easy_setopt(curl, CURLOPT_CONNECT_TO, connect_to);
                     97:   curl_easy_setopt(curl, CURLOPT_URL, "http://example.com");
                     98: 
                     99:   curl_easy_perform(curl);
                    100: 
                    101:   /* always cleanup */
                    102:   curl_easy_cleanup(curl);
                    103: }
                    104: 
                    105: curl_slist_free_all(connect_to);
                    106: .fi
                    107: .SH AVAILABILITY
                    108: Added in 7.49.0
                    109: .SH RETURN VALUE
                    110: Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.
                    111: .SH "SEE ALSO"
                    112: .BR CURLOPT_URL "(3), " CURLOPT_RESOLVE "(3), " CURLOPT_FOLLOWLOCATION "(3), " CURLOPT_HTTPPROXYTUNNEL  "(3), "