CURLOPT_TCP_FASTOPEN(3) | Library Functions Manual | 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 (RFC 7413) 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
This functionality affects tcp only
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_TCP_FASTOPEN, 1L); curl_easy_perform(curl); } }
NOTES
This option is only supported on Linux and macOS 10.11 or later.
AVAILABILITY
Added in curl 7.49.0
RETURN VALUE
Returns CURLE_OK if fast open is supported by the operating system, otherwise returns CURLE_NOT_BUILT_IN.
SEE ALSO
2024-09-18 | libcurl |