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.TH CURLOPT_SSL_FALSESTART 3 "January 02, 2023" "libcurl 7.88.1" "curl_easy_setopt options"

.SH NAME
CURLOPT_SSL_FALSESTART \- TLS false start
.SH SYNOPSIS
.nf
#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSL_FALSESTART, long enable);
.fi
.SH 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 will start sending
application data before verifying the server's Finished message, thus saving a
round trip when performing a full handshake.
.SH DEFAULT
0
.SH PROTOCOLS
All TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc.
.SH EXAMPLE
.nf
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);
}
.fi
.SH AVAILABILITY
Added in 7.42.0. This option is currently only supported by the NSS and
Secure Transport (on iOS 7.0 or later, or OS X 10.9 or later) TLS backends.
.SH RETURN VALUE
Returns CURLE_OK if false start is supported by the SSL backend, otherwise
returns CURLE_NOT_BUILT_IN.
.SH SEE ALSO
.BR CURLOPT_TCP_FASTOPEN "(3), "