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---
c: Copyright (C) Daniel Stenberg, <daniel.se>, et al.
SPDX-License-Identifier: curl
Title: CURLOPT_CONNECT_ONLY
Section: 3
Source: libcurl
See-also:
- CURLOPT_HTTPPROXYTUNNEL (3)
- CURLOPT_VERBOSE (3)
- curl_easy_recv (3)
- curl_easy_send (3)
---
# NAME
CURLOPT_CONNECT_ONLY - stop when connected to target server
# SYNOPSIS
~~~c
#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
0
# PROTOCOLS
HTTP, SMTP, POP3 and IMAP. For WS and WSS starting in 7.86.0.
# EXAMPLE
~~~c
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! */
}
}
}
~~~
# AVAILABILITY
Added in 7.15.2
# RETURN VALUE
Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.
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