NAME

       CURLOPT_TCP_FASTOPEN - enable 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 (RFC7413) 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).

DEFAULT

       0

PROTOCOLS

       All

EXAMPLE

       CURL *curl = curl_easy_init();
       if(curl) {
         curl_easy_setopt(curl, CURLOPT_URL, "http://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  OS X El Capitan.

RETURN VALUE

       Returns  CURLE_OK  if  fast  open  is supported by the operating system, otherwise returns
       CURLE_NOT_BUILT_IN.