CURLOPT_SSL_FALSESTART - TLS false start

Added in curl 7.42.0

0

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.

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); } }

CURLOPT_SSL_FALSESTART - TLS false start

This functionality affects all TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc. This option works only with the following TLS backends: Secure Transport

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).

CURLOPT_TCP_FASTOPEN(3) libcurl 2025-06-16 CURLOPT_SSL_FALSESTART(3)

#include <curl/curl.h> CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSL_FALSESTART, long enable);