1.3 KiB
1.3 KiB
c | SPDX-License-Identifier | Title | Section | Source | See-also | |
---|---|---|---|---|---|---|
Copyright (C) Daniel Stenberg, <daniel.se>, et al. | curl | CURLOPT_TCP_FASTOPEN | 3 | libcurl |
|
NAME
CURLOPT_TCP_FASTOPEN - TCP Fast Open
SYNOPSIS
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_TCP_FASTOPEN, long enable);
DESCRIPTION
Pass a long as parameter set to 1L to enable or 0 to disable.
TCP Fast Open (RFC 7413) is a mechanism that allows data to be carried in the SYN and SYN-ACK packets and consumed by the receiving end during the initial connection handshake, saving up to one full round-trip time (RTT).
Beware: the TLS session cache does not work when TCP Fast Open is enabled. TCP Fast Open is also known to be problematic on or across certain networks.
DEFAULT
0
PROTOCOLS
All
EXAMPLE
int main(void)
{
CURL *curl = curl_easy_init();
if(curl) {
curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
curl_easy_setopt(curl, CURLOPT_TCP_FASTOPEN, 1L);
curl_easy_perform(curl);
}
}
AVAILABILITY
Added in 7.49.0. This option is currently only supported on Linux and macOS 10.11 or later.
RETURN VALUE
Returns CURLE_OK if fast open is supported by the operating system, otherwise returns CURLE_NOT_BUILT_IN.