CURLOPT_TCP_FASTOPEN(3)

1CURLOPT_TCP_FASTOPEN(3)    curl_easy_setopt options    CURLOPT_TCP_FASTOPEN(3)
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NAME

6       CURLOPT_TCP_FASTOPEN - TCP Fast Open
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SYNOPSIS

9       #include <curl/curl.h>
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11       CURLcode  curl_easy_setopt(CURL *handle, CURLOPT_TCP_FASTOPEN, long en‐
12       able);
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DESCRIPTION

15       Pass a long as parameter set to 1L to enable or 0 to disable.
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17       TCP Fast Open (RFC7413) is a mechanism that allows data to  be  carried
18       in the SYN and SYN-ACK packets and consumed by the receiving end during
19       the initial connection handshake, saving up to one full round-trip time
20       (RTT).
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DEFAULT

23       0
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PROTOCOLS

26       All
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EXAMPLE

29       CURL *curl = curl_easy_init();
30       if(curl) {
31         curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
32         curl_easy_setopt(curl, CURLOPT_TCP_FASTOPEN, 1L);
33         curl_easy_perform(curl);
34       }
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AVAILABILITY

37       Added  in  7.49.0. This option is currently only supported on Linux and
38       OS X El Capitan.
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RETURN VALUE

41       Returns CURLE_OK if fast open is supported  by  the  operating  system,
42       otherwise returns CURLE_NOT_BUILT_IN.
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