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539c073cf0
- At high data rates more buffer space is required in order to avoid
packet loss during any cause of delay.
- On slower machines more buffer space is required in order to avoid
packet loss while decryption & tun writing is underway.
- On higher latency network paths more buffer space is required in order
to overcome BDP.
- On Linux set with SO_*BUFFORCE to bypass net.core.{r,w}mem_max.
- 7MB is the current default maximum on macOS 12.6
- Windows test is omitted, as Windows does not support getsockopt for
these options.
Signed-off-by: James Tucker <james@tailscale.com>
63 lines
1.4 KiB
Go
63 lines
1.4 KiB
Go
// Copyright (c) 2022 Tailscale Inc & AUTHORS All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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//go:build unix
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// +build unix
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package magicsock
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import (
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"net"
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"syscall"
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"testing"
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"tailscale.com/types/nettype"
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)
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func TestTrySetSocketBuffer(t *testing.T) {
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c, err := net.ListenPacket("udp", ":0")
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if err != nil {
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t.Fatal(err)
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}
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defer c.Close()
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rc, err := c.(*net.UDPConn).SyscallConn()
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if err != nil {
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t.Fatal(err)
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}
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getBufs := func() (int, int) {
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var rcv, snd int
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rc.Control(func(fd uintptr) {
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rcv, err = syscall.GetsockoptInt(int(fd), syscall.SOL_SOCKET, syscall.SO_RCVBUF)
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if err != nil {
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t.Errorf("getsockopt(SO_RCVBUF): %v", err)
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}
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snd, err = syscall.GetsockoptInt(int(fd), syscall.SOL_SOCKET, syscall.SO_SNDBUF)
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if err != nil {
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t.Errorf("getsockopt(SO_SNDBUF): %v", err)
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}
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})
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return rcv, snd
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}
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curRcv, curSnd := getBufs()
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trySetSocketBuffer(c.(nettype.PacketConn), t.Logf)
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newRcv, newSnd := getBufs()
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if curRcv > newRcv {
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t.Errorf("SO_RCVBUF decreased: %v -> %v", curRcv, newRcv)
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}
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if curSnd > newSnd {
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t.Errorf("SO_SNDBUF decreased: %v -> %v", curSnd, newSnd)
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}
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// On many systems we may not increase the value, particularly running as a
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// regular user, so log the information for manual verification.
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t.Logf("SO_RCVBUF: %v -> %v", curRcv, newRcv)
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t.Logf("SO_SNDBUF: %v -> %v", curRcv, newRcv)
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}
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