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Copy TCP GRO probe from tailscale

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世界 2024-11-23 13:13:48 +08:00
parent 6ef42f019b
commit c177abb523
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GPG key ID: CD109927C34A63C4
2 changed files with 49 additions and 16 deletions
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2
tun.go
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@ -40,8 +40,6 @@ type LinuxTUN interface {
BatchSize() int
BatchRead(buffers [][]byte, offset int, readN []int) (n int, err error)
BatchWrite(buffers [][]byte, offset int) (n int, err error)
DisableUDPGRO()
DisableTCPGRO()
TXChecksumOffload() bool
}

63
tun_linux.go
View file

@ -14,6 +14,8 @@ import (
"unsafe"
"github.com/sagernet/netlink"
"github.com/sagernet/sing-tun/internal/gtcpip/checksum"
"github.com/sagernet/sing-tun/internal/gtcpip/header"
"github.com/sagernet/sing/common"
"github.com/sagernet/sing/common/buf"
"github.com/sagernet/sing/common/bufio"
@ -194,20 +196,44 @@ func (t *NativeTun) BatchSize() int {
return idealBatchSize
}
// DisableUDPGRO disables UDP GRO if it is enabled. See the GRODevice interface
// for cases where it should be called.
func (t *NativeTun) DisableUDPGRO() {
t.writeAccess.Lock()
t.gro.disableUDPGRO()
t.writeAccess.Unlock()
}
// DisableTCPGRO disables TCP GRO if it is enabled. See the GRODevice interface
// for cases where it should be called.
func (t *NativeTun) DisableTCPGRO() {
t.writeAccess.Lock()
t.gro.disableTCPGRO()
t.writeAccess.Unlock()
func (t *NativeTun) probeTCPGRO() error {
ipPort := netip.AddrPortFrom(t.options.Inet4Address[0].Addr(), 0)
fingerprint := []byte("sing-tun-probe-tun-gro")
segmentSize := len(fingerprint)
iphLen := 20
tcphLen := 20
totalLen := iphLen + tcphLen + segmentSize
bufs := make([][]byte, 2)
for i := range bufs {
bufs[i] = make([]byte, virtioNetHdrLen+totalLen, virtioNetHdrLen+(totalLen*2))
ipv4H := header.IPv4(bufs[i][virtioNetHdrLen:])
ipv4H.Encode(&header.IPv4Fields{
SrcAddr: ipPort.Addr(),
DstAddr: ipPort.Addr(),
Protocol: unix.IPPROTO_TCP,
// Use a zero value TTL as best effort means to reduce chance of
// probe packet leaking further than it needs to.
TTL: 0,
TotalLength: uint16(totalLen),
})
tcpH := header.TCP(bufs[i][virtioNetHdrLen+iphLen:])
tcpH.Encode(&header.TCPFields{
SrcPort: ipPort.Port(),
DstPort: ipPort.Port(),
SeqNum: 1 + uint32(i*segmentSize),
AckNum: 1,
DataOffset: 20,
Flags: header.TCPFlagAck,
WindowSize: 3000,
})
copy(bufs[i][virtioNetHdrLen+iphLen+tcphLen:], fingerprint)
ipv4H.SetChecksum(^ipv4H.CalculateChecksum())
pseudoCsum := header.PseudoHeaderChecksum(unix.IPPROTO_TCP, ipv4H.SourceAddressSlice(), ipv4H.DestinationAddressSlice(), uint16(tcphLen+segmentSize))
pseudoCsum = checksum.Checksum(bufs[i][virtioNetHdrLen+iphLen+tcphLen:], pseudoCsum)
tcpH.SetChecksum(^tcpH.CalculateChecksum(pseudoCsum))
}
_, err := t.BatchWrite(bufs, virtioNetHdrLen)
return err
}
func (t *NativeTun) BatchRead(buffers [][]byte, offset int, readN []int) (n int, err error) {
@ -397,6 +423,15 @@ func (t *NativeTun) Start() error {
return err
}
if t.vnetHdr && len(t.options.Inet4Address) > 0 {
err = t.probeTCPGRO()
if err != nil {
t.gro.disableTCPGRO()
t.gro.disableUDPGRO()
t.options.Logger.Warn(E.Cause(err, "disabled TUN TCP & UDP GRO due to GRO probe error"))
}
}
if t.options.IPRoute2TableIndex == 0 {
for {
t.options.IPRoute2TableIndex = int(rand.Uint32())