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Revert "wgengine,net,ipn,disco: split up and define different types of MTU"

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This reverts commit 059051c58a.

Signed-off-by: Val <valerie@tailscale.com>
This commit is contained in:
Val
2023-09-22 19:44:59 +02:00
committed by valscale
parent 059051c58a
commit 6cc5b272d8
7 changed files with 52 additions and 250 deletions
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90
net/tstun/mtu_test.go
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@@ -4,93 +4,25 @@ package tstun
import (
"os"
"strconv"
"testing"
)
// Test the default MTU in the presence of various envknobs.
func TestDefaultTunMTU(t *testing.T) {
// Save and restore the envknobs we will be changing.
func TestDefaultMTU(t *testing.T) {
orig := os.Getenv("TS_DEBUG_MTU")
defer os.Setenv("TS_DEBUG_MTU", orig)
// TS_DEBUG_MTU sets the MTU to a specific value.
defer os.Setenv("TS_DEBUG_MTU", os.Getenv("TS_DEBUG_MTU"))
os.Setenv("TS_DEBUG_MTU", "")
// TS_DEBUG_ENABLE_PMTUD enables path MTU discovery.
defer os.Setenv("TS_DEBUG_ENABLE_PMTUD", os.Getenv("TS_DEBUG_ENABLE_PMTUD"))
os.Setenv("TS_DEBUG_ENABLE_PMTUD", "")
// With no MTU envknobs set, we should get the conservative MTU.
if DefaultTUNMTU() != safeTUNMTU {
t.Errorf("default TUN MTU = %d, want %d", DefaultTUNMTU(), safeTUNMTU)
if DefaultMTU() != 1280 {
t.Errorf("DefaultMTU() = %d, want 1280", DefaultMTU())
}
// If set, TS_DEBUG_MTU should set the MTU.
mtu := maxTUNMTU - 1
os.Setenv("TS_DEBUG_MTU", strconv.Itoa(int(mtu)))
if DefaultTUNMTU() != mtu {
t.Errorf("default TUN MTU = %d, want %d, TS_DEBUG_MTU ignored", DefaultTUNMTU(), mtu)
os.Setenv("TS_DEBUG_MTU", "9000")
if DefaultMTU() != 9000 {
t.Errorf("DefaultMTU() = %d, want 9000", DefaultMTU())
}
// MTU should be clamped to maxTunMTU.
mtu = maxTUNMTU + 1
os.Setenv("TS_DEBUG_MTU", strconv.Itoa(int(mtu)))
if DefaultTUNMTU() != maxTUNMTU {
t.Errorf("default TUN MTU = %d, want %d, clamping failed", DefaultTUNMTU(), maxTUNMTU)
}
// If PMTUD is enabled, the MTU should default to the largest probed
// MTU, but only if the user hasn't requested a specific MTU.
os.Setenv("TS_DEBUG_MTU", "")
os.Setenv("TS_DEBUG_ENABLE_PMTUD", "true")
if DefaultTUNMTU() != WireToTUNMTU(MaxProbedWireMTU) {
t.Errorf("default TUN MTU = %d, want %d", DefaultTUNMTU(), WireToTUNMTU(MaxProbedWireMTU))
}
// TS_DEBUG_MTU should take precedence over TS_DEBUG_ENABLE_PMTUD.
mtu = WireToTUNMTU(MaxProbedWireMTU - 1)
os.Setenv("TS_DEBUG_MTU", strconv.Itoa(int(mtu)))
if DefaultTUNMTU() != mtu {
t.Errorf("default TUN MTU = %d, want %d", DefaultTUNMTU(), mtu)
}
}
// Test the conversion of wire MTU to/from Tailscale TUN MTU corner cases.
func TestMTUConversion(t *testing.T) {
tests := []struct {
w WireMTU
t TUNMTU
}{
{w: 0, t: 0},
{w: wgHeaderLen - 1, t: 0},
{w: wgHeaderLen, t: 0},
{w: wgHeaderLen + 1, t: 1},
{w: 1360, t: 1280},
{w: 1500, t: 1420},
{w: 9000, t: 8920},
}
for _, tt := range tests {
m := WireToTUNMTU(tt.w)
if m != tt.t {
t.Errorf("conversion of wire MTU %v to TUN MTU = %v, want %v", tt.w, m, tt.t)
}
}
tests2 := []struct {
t TUNMTU
w WireMTU
}{
{t: 0, w: wgHeaderLen},
{t: 1, w: wgHeaderLen + 1},
{t: 1280, w: 1360},
{t: 1420, w: 1500},
{t: 8920, w: 9000},
}
for _, tt := range tests2 {
m := TUNToWireMTU(tt.t)
if m != tt.w {
t.Errorf("conversion of TUN MTU %v to wire MTU = %v, want %v", tt.t, m, tt.w)
}
os.Setenv("TS_DEBUG_MTU", "123456789")
if DefaultMTU() != maxMTU {
t.Errorf("DefaultMTU() = %d, want %d", DefaultMTU(), maxMTU)
}
}