CURLOPT_SSL_FALSESTART(3)  Library Functions Manual  CURLOPT_SSL_FALSESTART(3)

NAME
       CURLOPT_SSL_FALSESTART - TLS false start

SYNOPSIS
       #include <curl/curl.h>

       CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSL_FALSESTART, long enable);

DESCRIPTION
       Pass a long as parameter set to 1L to enable or 0 to disable.

       This option determines whether libcurl should use false start during
       the TLS handshake. False start is a mode where a TLS client starts
       sending application data before verifying the server's Finished
       message, thus saving a round trip when performing a full handshake.

DEFAULT
       0

PROTOCOLS
       This functionality affects all TLS based protocols: HTTPS, FTPS, IMAPS,
       POP3S, SMTPS etc.

       This option works only with the following TLS backends: Secure
       Transport

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_SSL_FALSESTART, 1L);
           curl_easy_perform(curl);
         }
       }

AVAILABILITY
       Added in curl 7.42.0

RETURN VALUE
       curl_easy_setopt(3) returns a CURLcode indicating success or error.

       CURLE_OK (0) means everything was OK, non-zero means an error occurred,
       see libcurl-errors(3).

SEE ALSO
       CURLOPT_TCP_FASTOPEN(3)

libcurl                           2025-02-13         CURLOPT_SSL_FALSESTART(3)