64 lines
1.9 KiB
Go
64 lines
1.9 KiB
Go
// Copyright (C) 2023 Storj Labs, Inc.
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// See LICENSE for copying information.
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package server
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import (
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"fmt"
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"os"
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"strconv"
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"strings"
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"sync"
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"syscall"
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"go.uber.org/zap"
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)
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const tcpFastOpen = 0x17
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const tcpFastOpenSysctlPath = "/proc/sys/net/ipv4/tcp_fastopen"
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func setTCPFastOpen(fd uintptr, queue int) error {
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return syscall.SetsockoptInt(int(fd), syscall.IPPROTO_TCP, tcpFastOpen, queue)
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}
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var tryInitFastOpenOnce sync.Once
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var initFastOpenPossiblyEnabled bool
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// tryInitFastOpen returns true if fastopen support is possibly enabled.
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func tryInitFastOpen(log *zap.Logger) bool {
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tryInitFastOpenOnce.Do(func() {
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data, err := os.ReadFile(tcpFastOpenSysctlPath)
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if err != nil {
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log.Sugar().Infof("kernel support for tcp fast open unknown")
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initFastOpenPossiblyEnabled = true
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return
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}
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fastOpenFlags, err := strconv.Atoi(strings.TrimSpace(string(data)))
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if err != nil {
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log.Sugar().Infof("kernel support for tcp fast open unparsable")
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initFastOpenPossiblyEnabled = true
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return
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}
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if fastOpenFlags&0x2 != 0 {
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log.Sugar().Infof("existing kernel support for server-side tcp fast open detected")
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initFastOpenPossiblyEnabled = true
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return
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}
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err = os.WriteFile(tcpFastOpenSysctlPath, []byte(fmt.Sprint(fastOpenFlags|0x2)), 0o644)
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if err != nil {
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log.Sugar().Infof("kernel support for server-side tcp fast open remains disabled.")
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// really, it's just the secondmost least significant bit that needs to
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// be flipped, but maybe this isn't the place to explain that. 0x3 will
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// enable standard fast open with standard cookies for both clients and
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// servers, so it's probably the right advice.
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log.Sugar().Infof("enable with: sysctl -w net.ipv4.tcp_fastopen=3")
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initFastOpenPossiblyEnabled = false
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return
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}
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log.Sugar().Infof("kernel support for server-side tcp fast open enabled.")
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initFastOpenPossiblyEnabled = true
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})
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return initFastOpenPossiblyEnabled
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}
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