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Vision padding upgrade (#1646)

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* Vision server allow multiple blocks of padding

* Fix Vision client to support multiple possible padding blocks

* Vision padding upgrade

- Now we have two types of padding: long (pad to 900-1400) and traditional (0-256)
- Long padding is applied to tls handshakes and first (empty) packet
- Traditional padding is applied to all beginning (7) packets of the connection (counted two-way)
- Since receiver changed its way to unpad buffer in fd6973b3c6, we can freely extend padding packet length easily in the future
- Simplify code

* Adjust receiver withinPaddingBuffers

Now default withinPaddingBuffers = true to give it a chance to do unpadding

* Fix magic numbers for Vision
Thanks @H1JK

Thanks @RPRX for guidance
pull/1725/head
yuhan6665 2 years ago committed by GitHub
parent 55dc26f228
commit 2d898480be
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
3 changed files with 63 additions and 44 deletions
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86
proxy/vless/encoding/encoding.go
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@ -36,6 +36,23 @@ var (
tlsClientHandShakeStart = []byte{0x16, 0x03}
tlsServerHandShakeStart = []byte{0x16, 0x03, 0x03}
tlsApplicationDataStart = []byte{0x17, 0x03, 0x03}
Tls13CipherSuiteDic = map[uint16]string{
0x1301: "TLS_AES_128_GCM_SHA256",
0x1302: "TLS_AES_256_GCM_SHA384",
0x1303: "TLS_CHACHA20_POLY1305_SHA256",
0x1304: "TLS_AES_128_CCM_SHA256",
0x1305: "TLS_AES_128_CCM_8_SHA256",
}
)
const (
tlsHandshakeTypeClientHello byte = 0x01
tlsHandshakeTypeServerHello byte = 0x02
CommandPaddingContinue byte = 0x00
CommandPaddingEnd byte = 0x01
CommandPaddingDirect byte = 0x02
)
var addrParser = protocol.NewAddressParser(
@ -256,7 +273,7 @@ func XtlsRead(reader buf.Reader, writer buf.Writer, timer signal.ActivityUpdater
) error {
err := func() error {
var ct stats.Counter
filterUUID := true
withinPaddingBuffers := true
shouldSwitchToDirectCopy := false
var remainingContent int32 = -1
var remainingPadding int32 = -1
@ -294,13 +311,15 @@ func XtlsRead(reader buf.Reader, writer buf.Writer, timer signal.ActivityUpdater
}
buffer, err := reader.ReadMultiBuffer()
if !buffer.IsEmpty() {
if filterUUID && (*isTLS || *numberOfPacketToFilter > 0) {
if withinPaddingBuffers || *numberOfPacketToFilter > 0 {
buffer = XtlsUnpadding(ctx, buffer, userUUID, &remainingContent, &remainingPadding, &currentCommand)
if remainingContent == 0 && remainingPadding == 0 {
if currentCommand == 1 {
filterUUID = false
withinPaddingBuffers = false
remainingContent = -1
remainingPadding = -1 // set to initial state to parse the next padding
} else if currentCommand == 2 {
filterUUID = false
withinPaddingBuffers = false
shouldSwitchToDirectCopy = true
// XTLS Vision processes struct TLS Conn's input and rawInput
if inputBuffer, err := buf.ReadFrom(input); err == nil {
@ -313,9 +332,15 @@ func XtlsRead(reader buf.Reader, writer buf.Writer, timer signal.ActivityUpdater
buffer, _ = buf.MergeMulti(buffer, rawInputBuffer)
}
}
} else if currentCommand != 0 {
} else if currentCommand == 0 {
withinPaddingBuffers = true
} else {
newError("XtlsRead unknown command ", currentCommand, buffer.Len()).WriteToLog(session.ExportIDToError(ctx))
}
} else if remainingContent > 0 || remainingPadding > 0 {
withinPaddingBuffers = true
} else {
withinPaddingBuffers = false
}
}
if *numberOfPacketToFilter > 0 {
@ -342,12 +367,12 @@ func XtlsRead(reader buf.Reader, writer buf.Writer, timer signal.ActivityUpdater
// XtlsWrite filter and write xtls protocol
func XtlsWrite(reader buf.Reader, writer buf.Writer, timer signal.ActivityUpdater, conn net.Conn, counter stats.Counter,
ctx context.Context, userUUID *[]byte, numberOfPacketToFilter *int, enableXtls *bool, isTLS12orAbove *bool, isTLS *bool,
ctx context.Context, numberOfPacketToFilter *int, enableXtls *bool, isTLS12orAbove *bool, isTLS *bool,
cipher *uint16, remainingServerHello *int32,
) error {
err := func() error {
var ct stats.Counter
filterTlsApplicationData := true
isPadding := true
shouldSwitchToDirectCopy := false
for {
buffer, err := reader.ReadMultiBuffer()
@ -355,27 +380,26 @@ func XtlsWrite(reader buf.Reader, writer buf.Writer, timer signal.ActivityUpdate
if *numberOfPacketToFilter > 0 {
XtlsFilterTls(buffer, numberOfPacketToFilter, enableXtls, isTLS12orAbove, isTLS, cipher, remainingServerHello, ctx)
}
if filterTlsApplicationData && *isTLS {
if isPadding {
buffer = ReshapeMultiBuffer(ctx, buffer)
var xtlsSpecIndex int
for i, b := range buffer {
if b.Len() >= 6 && bytes.Equal(tlsApplicationDataStart, b.BytesTo(3)) {
var command byte = 0x01
if *isTLS && b.Len() >= 6 && bytes.Equal(tlsApplicationDataStart, b.BytesTo(3)) {
var command byte = CommandPaddingEnd
if *enableXtls {
shouldSwitchToDirectCopy = true
xtlsSpecIndex = i
command = 0x02
command = CommandPaddingDirect
}
filterTlsApplicationData = false
buffer[i] = XtlsPadding(b, command, userUUID, ctx)
isPadding = false
buffer[i] = XtlsPadding(b, command, nil, *isTLS, ctx)
break
} else if !*isTLS12orAbove && *numberOfPacketToFilter <= 0 {
// maybe tls 1.1 or 1.0
filterTlsApplicationData = false
buffer[i] = XtlsPadding(b, 0x01, userUUID, ctx)
} else if !*isTLS12orAbove && *numberOfPacketToFilter <= 1 { // For compatibility with earlier vision receiver, we finish padding 1 packet early
isPadding = false
buffer[i] = XtlsPadding(b, CommandPaddingEnd, nil, *isTLS, ctx)
break
}
buffer[i] = XtlsPadding(b, 0x00, userUUID, ctx)
buffer[i] = XtlsPadding(b, CommandPaddingContinue, nil, *isTLS, ctx)
}
if shouldSwitchToDirectCopy {
encryptBuffer, directBuffer := buf.SplitMulti(buffer, xtlsSpecIndex+1)
@ -422,7 +446,7 @@ func XtlsFilterTls(buffer buf.MultiBuffer, numberOfPacketToFilter *int, enableXt
*numberOfPacketToFilter--
if b.Len() >= 6 {
startsBytes := b.BytesTo(6)
if bytes.Equal(tlsServerHandShakeStart, startsBytes[:3]) && startsBytes[5] == 0x02 {
if bytes.Equal(tlsServerHandShakeStart, startsBytes[:3]) && startsBytes[5] == tlsHandshakeTypeServerHello {
*remainingServerHello = (int32(startsBytes[3])<<8 | int32(startsBytes[4])) + 5
*isTLS12orAbove = true
*isTLS = true
@ -433,7 +457,7 @@ func XtlsFilterTls(buffer buf.MultiBuffer, numberOfPacketToFilter *int, enableXt
} else {
newError("XtlsFilterTls short server hello, tls 1.2 or older? ", b.Len(), " ", *remainingServerHello).WriteToLog(session.ExportIDToError(ctx))
}
} else if bytes.Equal(tlsClientHandShakeStart, startsBytes[:2]) && startsBytes[5] == 0x01 {
} else if bytes.Equal(tlsClientHandShakeStart, startsBytes[:2]) && startsBytes[5] == tlsHandshakeTypeClientHello {
*isTLS = true
newError("XtlsFilterTls found tls client hello! ", buffer.Len()).WriteToLog(session.ExportIDToError(ctx))
}
@ -483,7 +507,7 @@ func ReshapeMultiBuffer(ctx context.Context, buffer buf.MultiBuffer) buf.MultiBu
for i, buffer1 := range buffer {
if buffer1.Len() >= buf.Size-21 {
index := int32(bytes.LastIndex(buffer1.Bytes(), tlsApplicationDataStart))
if index <= 0 {
if index <= 0 || index > buf.Size-21 {
index = buf.Size / 2
}
buffer2 := buf.New()
@ -503,23 +527,28 @@ func ReshapeMultiBuffer(ctx context.Context, buffer buf.MultiBuffer) buf.MultiBu
}
// XtlsPadding add padding to eliminate length siganature during tls handshake
func XtlsPadding(b *buf.Buffer, command byte, userUUID *[]byte, ctx context.Context) *buf.Buffer {
func XtlsPadding(b *buf.Buffer, command byte, userUUID *[]byte, longPadding bool, ctx context.Context) *buf.Buffer {
var contantLen int32 = 0
var paddingLen int32 = 0
if b != nil {
contantLen = b.Len()
}
if contantLen < 900 {
if contantLen < 900 && longPadding {
l, err := rand.Int(rand.Reader, big.NewInt(500))
if err != nil {
newError("failed to generate padding").Base(err).WriteToLog(session.ExportIDToError(ctx))
}
paddingLen = int32(l.Int64()) + 900 - contantLen
} else {
l, err := rand.Int(rand.Reader, big.NewInt(256))
if err != nil {
newError("failed to generate padding").Base(err).WriteToLog(session.ExportIDToError(ctx))
}
paddingLen = int32(l.Int64())
}
newbuffer := buf.New()
if userUUID != nil {
newbuffer.Write(*userUUID)
*userUUID = nil
}
newbuffer.Write([]byte{command, byte(contantLen >> 8), byte(contantLen), byte(paddingLen >> 8), byte(paddingLen)})
if b != nil {
@ -543,6 +572,7 @@ func XtlsUnpadding(ctx context.Context, buffer buf.MultiBuffer, userUUID []byte,
posByte = 16
*remainingContent = 0
*remainingPadding = 0
*currentCommand = 0
break
}
}
@ -601,11 +631,3 @@ func XtlsUnpadding(ctx context.Context, buffer buf.MultiBuffer, userUUID []byte,
buf.ReleaseMulti(buffer)
return mb2
}
var Tls13CipherSuiteDic = map[uint16]string{
0x1301: "TLS_AES_128_GCM_SHA256",
0x1302: "TLS_AES_256_GCM_SHA384",
0x1303: "TLS_CHACHA20_POLY1305_SHA256",
0x1304: "TLS_AES_128_CCM_SHA256",
0x1305: "TLS_AES_128_CCM_8_SHA256",
}

10
proxy/vless/inbound/inbound.go
Unescape View File

@ -624,11 +624,9 @@ func (h *Handler) Process(ctx context.Context, network net.Network, connection s
}
if requestAddons.Flow == vless.XRV {
encoding.XtlsFilterTls(multiBuffer, &numberOfPacketToFilter, &enableXtls, &isTLS12orAbove, &isTLS, &cipher, &remainingServerHello, ctx)
if isTLS {
multiBuffer = encoding.ReshapeMultiBuffer(ctx, multiBuffer)
for i, b := range multiBuffer {
multiBuffer[i] = encoding.XtlsPadding(b, 0x00, &userUUID, ctx)
}
multiBuffer = encoding.ReshapeMultiBuffer(ctx, multiBuffer)
for i, b := range multiBuffer {
multiBuffer[i] = encoding.XtlsPadding(b, encoding.CommandPaddingContinue, &userUUID, isTLS, ctx)
}
}
if err := clientWriter.WriteMultiBuffer(multiBuffer); err != nil {
@ -645,7 +643,7 @@ func (h *Handler) Process(ctx context.Context, network net.Network, connection s
if statConn != nil {
counter = statConn.WriteCounter
}
err = encoding.XtlsWrite(serverReader, clientWriter, timer, netConn, counter, ctx, &userUUID, &numberOfPacketToFilter,
err = encoding.XtlsWrite(serverReader, clientWriter, timer, netConn, counter, ctx, &numberOfPacketToFilter,
&enableXtls, &isTLS12orAbove, &isTLS, &cipher, &remainingServerHello)
} else {
// from serverReader.ReadMultiBuffer to clientWriter.WriteMultiBufer

11
proxy/vless/outbound/outbound.go
Unescape View File

@ -243,10 +243,9 @@ func (h *Handler) Process(ctx context.Context, link *transport.Link, dialer inte
if err1 == nil {
if requestAddons.Flow == vless.XRV {
encoding.XtlsFilterTls(multiBuffer, &numberOfPacketToFilter, &enableXtls, &isTLS12orAbove, &isTLS, &cipher, &remainingServerHello, ctx)
if isTLS {
for i, b := range multiBuffer {
multiBuffer[i] = encoding.XtlsPadding(b, 0x00, &userUUID, ctx)
}
multiBuffer = encoding.ReshapeMultiBuffer(ctx, multiBuffer)
for i, b := range multiBuffer {
multiBuffer[i] = encoding.XtlsPadding(b, encoding.CommandPaddingContinue, &userUUID, isTLS, ctx)
}
}
if err := serverWriter.WriteMultiBuffer(multiBuffer); err != nil {
@ -256,7 +255,7 @@ func (h *Handler) Process(ctx context.Context, link *transport.Link, dialer inte
return err1
} else if requestAddons.Flow == vless.XRV {
mb := make(buf.MultiBuffer, 1)
mb[0] = encoding.XtlsPadding(nil, 0x01, &userUUID, ctx) // it must not be tls so padding finish with it (command 1)
mb[0] = encoding.XtlsPadding(nil, encoding.CommandPaddingContinue, &userUUID, true, ctx) // we do a long padding to hide vless header
newError("Insert padding with empty content to camouflage VLESS header ", mb.Len()).WriteToLog(session.ExportIDToError(ctx))
if err := serverWriter.WriteMultiBuffer(mb); err != nil {
return err
@ -285,7 +284,7 @@ func (h *Handler) Process(ctx context.Context, link *transport.Link, dialer inte
if statConn != nil {
counter = statConn.WriteCounter
}
err = encoding.XtlsWrite(clientReader, serverWriter, timer, netConn, counter, ctx, &userUUID, &numberOfPacketToFilter,
err = encoding.XtlsWrite(clientReader, serverWriter, timer, netConn, counter, ctx, &numberOfPacketToFilter,
&enableXtls, &isTLS12orAbove, &isTLS, &cipher, &remainingServerHello)
} else {
// from clientReader.ReadMultiBuffer to serverWriter.WriteMultiBufer

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