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net/neterror, wgengine/magicsock: use UDP GSO and GRO on Linux (#7791)

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This commit implements UDP offloading for Linux. GSO size is passed to
and from the kernel via socket control messages. Support is probed at
runtime.

UDP GSO is dependent on checksum offload support on the egress netdev.
UDP GSO will be disabled in the event sendmmsg() returns EIO, which is
a strong signal that the egress netdev does not support checksum
offload.

Updates tailscale/corp#8734

Signed-off-by: Jordan Whited <jordan@tailscale.com>
This commit is contained in:
Jordan Whited
2023-04-04 16:32:16 -07:00
committed by GitHub
parent 45138fcfba
commit f475e5550c
6 changed files with 780 additions and 198 deletions
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239
wgengine/magicsock/magicsock_test.go
View File

@@ -31,6 +31,7 @@ import (
"github.com/tailscale/wireguard-go/tun/tuntest"
"go4.org/mem"
"golang.org/x/exp/maps"
"golang.org/x/net/ipv6"
"tailscale.com/cmd/testwrapper/flakytest"
"tailscale.com/derp"
"tailscale.com/derp/derphttp"
@@ -1156,7 +1157,7 @@ func TestDiscoMessage(t *testing.T) {
box := peer1Priv.Shared(c.discoPrivate.Public()).Seal([]byte(payload))
pkt = append(pkt, box...)
got := c.handleDiscoMessage(pkt, netip.AddrPort{}, key.NodePublic{})
got := c.handleDiscoMessage(pkt, netip.AddrPort{}, key.NodePublic{}, discoRXPathUDP)
if !got {
t.Error("failed to open it")
}
@@ -1832,8 +1833,8 @@ func TestRebindingUDPConn(t *testing.T) {
t.Fatal(err)
}
defer realConn.Close()
c.setConnLocked(realConn.(nettype.PacketConn), "udp4")
c.setConnLocked(newBlockForeverConn(), "")
c.setConnLocked(realConn.(nettype.PacketConn), "udp4", 1)
c.setConnLocked(newBlockForeverConn(), "", 1)
}
// https://github.com/tailscale/tailscale/issues/6680: don't ignore
@@ -1861,3 +1862,235 @@ func TestBufferedDerpWritesBeforeDrop(t *testing.T) {
}
t.Logf("bufferedDerpWritesBeforeDrop = %d", vv)
}
func setGSOSize(control *[]byte, gsoSize uint16) {
*control = (*control)[:cap(*control)]
binary.LittleEndian.PutUint16(*control, gsoSize)
}
func getGSOSize(control []byte) (int, error) {
if len(control) < 2 {
return 0, nil
}
return int(binary.LittleEndian.Uint16(control)), nil
}
func Test_batchingUDPConn_splitCoalescedMessages(t *testing.T) {
c := &batchingUDPConn{
setGSOSizeInControl: setGSOSize,
getGSOSizeFromControl: getGSOSize,
}
newMsg := func(n, gso int) ipv6.Message {
msg := ipv6.Message{
Buffers: [][]byte{make([]byte, 1024)},
N: n,
OOB: make([]byte, 2),
}
binary.LittleEndian.PutUint16(msg.OOB, uint16(gso))
if gso > 0 {
msg.NN = 2
}
return msg
}
cases := []struct {
name string
msgs []ipv6.Message
firstMsgAt int
wantNumEval int
wantMsgLens []int
wantErr bool
}{
{
name: "second last split last empty",
msgs: []ipv6.Message{
newMsg(0, 0),
newMsg(0, 0),
newMsg(3, 1),
newMsg(0, 0),
},
firstMsgAt: 2,
wantNumEval: 3,
wantMsgLens: []int{1, 1, 1, 0},
wantErr: false,
},
{
name: "second last no split last empty",
msgs: []ipv6.Message{
newMsg(0, 0),
newMsg(0, 0),
newMsg(1, 0),
newMsg(0, 0),
},
firstMsgAt: 2,
wantNumEval: 1,
wantMsgLens: []int{1, 0, 0, 0},
wantErr: false,
},
{
name: "second last no split last no split",
msgs: []ipv6.Message{
newMsg(0, 0),
newMsg(0, 0),
newMsg(1, 0),
newMsg(1, 0),
},
firstMsgAt: 2,
wantNumEval: 2,
wantMsgLens: []int{1, 1, 0, 0},
wantErr: false,
},
{
name: "second last no split last split",
msgs: []ipv6.Message{
newMsg(0, 0),
newMsg(0, 0),
newMsg(1, 0),
newMsg(3, 1),
},
firstMsgAt: 2,
wantNumEval: 4,
wantMsgLens: []int{1, 1, 1, 1},
wantErr: false,
},
{
name: "second last split last split",
msgs: []ipv6.Message{
newMsg(0, 0),
newMsg(0, 0),
newMsg(2, 1),
newMsg(2, 1),
},
firstMsgAt: 2,
wantNumEval: 4,
wantMsgLens: []int{1, 1, 1, 1},
wantErr: false,
},
{
name: "second last no split last split overflow",
msgs: []ipv6.Message{
newMsg(0, 0),
newMsg(0, 0),
newMsg(1, 0),
newMsg(4, 1),
},
firstMsgAt: 2,
wantNumEval: 4,
wantMsgLens: []int{1, 1, 1, 1},
wantErr: true,
},
}
for _, tt := range cases {
t.Run(tt.name, func(t *testing.T) {
got, err := c.splitCoalescedMessages(tt.msgs, 2)
if err != nil && !tt.wantErr {
t.Fatalf("err: %v", err)
}
if got != tt.wantNumEval {
t.Fatalf("got to eval: %d want: %d", got, tt.wantNumEval)
}
for i, msg := range tt.msgs {
if msg.N != tt.wantMsgLens[i] {
t.Fatalf("msg[%d].N: %d want: %d", i, msg.N, tt.wantMsgLens[i])
}
}
})
}
}
func Test_batchingUDPConn_coalesceMessages(t *testing.T) {
c := &batchingUDPConn{
setGSOSizeInControl: setGSOSize,
getGSOSizeFromControl: getGSOSize,
}
cases := []struct {
name string
buffs [][]byte
wantLens []int
wantGSO []int
}{
{
name: "one message no coalesce",
buffs: [][]byte{
make([]byte, 1, 1),
},
wantLens: []int{1},
wantGSO: []int{0},
},
{
name: "two messages equal len coalesce",
buffs: [][]byte{
make([]byte, 1, 2),
make([]byte, 1, 1),
},
wantLens: []int{2},
wantGSO: []int{1},
},
{
name: "two messages unequal len coalesce",
buffs: [][]byte{
make([]byte, 2, 3),
make([]byte, 1, 1),
},
wantLens: []int{3},
wantGSO: []int{2},
},
{
name: "three messages second unequal len coalesce",
buffs: [][]byte{
make([]byte, 2, 3),
make([]byte, 1, 1),
make([]byte, 2, 2),
},
wantLens: []int{3, 2},
wantGSO: []int{2, 0},
},
{
name: "three messages limited cap coalesce",
buffs: [][]byte{
make([]byte, 2, 4),
make([]byte, 2, 2),
make([]byte, 2, 2),
},
wantLens: []int{4, 2},
wantGSO: []int{2, 0},
},
}
for _, tt := range cases {
t.Run(tt.name, func(t *testing.T) {
addr := &net.UDPAddr{
IP: net.ParseIP("127.0.0.1"),
Port: 1,
}
msgs := make([]ipv6.Message, len(tt.buffs))
for i := range msgs {
msgs[i].Buffers = make([][]byte, 1)
msgs[i].OOB = make([]byte, 0, 2)
}
got := c.coalesceMessages(addr, tt.buffs, msgs)
if got != len(tt.wantLens) {
t.Fatalf("got len %d want: %d", got, len(tt.wantLens))
}
for i := 0; i < got; i++ {
if msgs[i].Addr != addr {
t.Errorf("msgs[%d].Addr != passed addr", i)
}
gotLen := len(msgs[i].Buffers[0])
if gotLen != tt.wantLens[i] {
t.Errorf("len(msgs[%d].Buffers[0]) %d != %d", i, gotLen, tt.wantLens[i])
}
gotGSO, err := getGSOSize(msgs[i].OOB)
if err != nil {
t.Fatalf("msgs[%d] getGSOSize err: %v", i, err)
}
if gotGSO != tt.wantGSO[i] {
t.Errorf("msgs[%d] gsoSize %d != %d", i, gotGSO, tt.wantGSO[i])
}
}
})
}
}