CURLOPT_CONNECT_ONLY - stop when connected to target server
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_CONNECT_ONLY, long only);
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 will do the request and read all response headers before handing over
control to the application.
Transfers marked connect only will not reuse any existing connections and
connections marked connect only will not be 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.
0
HTTP, SMTP, POP3 and IMAP. For WS and WSS starting in 7.86.0.
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! */
}
}
Added in 7.15.2
Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.
CURLOPT_VERBOSE(3),
CURLOPT_HTTPPROXYTUNNEL(3),
curl_easy_recv(3),
curl_easy_send(3)