DragonFly On-Line Manual Pages

Search: Section:  

CURLOPT_TCP_FASTOPEN(3)             libcurl            CURLOPT_TCP_FASTOPEN(3)


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).

       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

       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),

ibcurl 8.1.2                    April 26, 2023         CURLOPT_TCP_FASTOPEN(3)

Search: Section: