Tribblix: manual page: CURLOPT_CONNECT

CURLOPT_CONNECT_ONLY(3) Introduction to Library Functions

NAME

CURLOPT_CONNECT_ONLY - stop when connected to target server

SYNOPSIS

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_CONNECT_ONLY, long only);

DESCRIPTION

Pass a long. If the parameter equals 1, it tells the library to
perform all the required proxy authentication and connection setup,
but no data transfer, and then return.

The option can be used to simply test a connection to a server, but
is more useful when used with the CURLINFO_ACTIVESOCKET(3) option to
curl_easy_getinfo(3) as the library can set up the connection and
then the application can obtain the most recently used socket for
special data transfers.

Since 7.86.0, this option can be set to '2' and if HTTP or WebSocket
are used, libcurl performs the request and reads all response headers
before handing over control to the application.

Transfers marked connect only do not reuse any existing connections
and connections marked connect only are not allowed to get reused.

If the connect only transfer is done using the multi interface, the
particular easy handle must remain added to the multi handle for as
long as the application wants to use it. Once it has been removed
with curl_multi_remove_handle(3), curl_easy_send(3) and
curl_easy_recv(3) do not function.

DEFAULT

PROTOCOLS

This functionality affects all supported protocols

EXAMPLE

int main(void)
{
CURL *curl = curl_easy_init();
if(curl) {
CURLcode ret;
curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
curl_easy_setopt(curl, CURLOPT_CONNECT_ONLY, 1L);
ret = curl_easy_perform(curl);
if(ret == CURLE_OK) {
/* only connected */
}
}
}

HISTORY

WS and WSS support added in 7.86.0.

AVAILABILITY

Added in curl 7.15.2

RETURN VALUE

curl_easy_setopt(3) returns a CURLcode indicating success or error.

CURLE_OK (0) means everything was OK, non-zero means an error
occurred, see libcurl-errors(3).