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 (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, "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.

SEE ALSO

       CURLOPT_SSL_FALSESTART(3),