Shadowsocks2022 Client Implementation Improvements (#2770)

* Shadowsocks2022 Client Implementation Improvements

1. Added UDP Replay Detection
2. Added UDP Processor State Cache
3. Added More Detailed Output for Time Difference Error
4. Replaced Mutex with RWMutex for reduced lock contention
5. Added per server session tracking of decryption cache and anti-replay window
6. Adjust server session track time
7. Increase per session buffer to 128
8. Fix client crash when EIH is not enabled
9. Fix client log contains non-human-friendly content
10.Remove mark and remove for trackedSessions
11. Fixed packet size uint16 overflow issue

common/crypto/auth.go

@@ -91,6 +91,7 @@ type AuthenticationReader struct {
 	transferType protocol.TransferType
 	padding      PaddingLengthGenerator
 	size         uint16
+	sizeOffset   uint16
 	paddingLen   uint16
 	hasSize      bool
 	done         bool
@@ -104,6 +105,9 @@ func NewAuthenticationReader(auth Authenticator, sizeParser ChunkSizeDecoder, re
 		padding:      paddingLen,
 		sizeBytes:    make([]byte, sizeParser.SizeBytes()),
 	}
+	if chunkSizeDecoderWithOffset, ok := sizeParser.(ChunkSizeDecoderWithOffset); ok {
+		r.sizeOffset = chunkSizeDecoderWithOffset.HasConstantOffset()
+	}
 	if breader, ok := reader.(*buf.BufferedReader); ok {
 		r.reader = breader
 	} else {
@@ -160,12 +164,14 @@ func (r *AuthenticationReader) readInternal(soft bool, mb *buf.MultiBuffer) erro
 		return err
 	}
 
-	if size == uint16(r.auth.Overhead())+padding {
+	if size+r.sizeOffset == uint16(r.auth.Overhead())+padding {
 		r.done = true
 		return io.EOF
 	}
 
-	if soft && int32(size) > r.reader.BufferedBytes() {
+	effectiveSize := int32(size) + int32(r.sizeOffset)
+
+	if soft && effectiveSize > r.reader.BufferedBytes() {
 		r.size = size
 		r.paddingLen = padding
 		r.hasSize = true
@@ -173,7 +179,7 @@ func (r *AuthenticationReader) readInternal(soft bool, mb *buf.MultiBuffer) erro
 	}
 
 	if size <= buf.Size {
-		b, err := r.readBuffer(int32(size), int32(padding))
+		b, err := r.readBuffer(effectiveSize, int32(padding))
 		if err != nil {
 			return nil
 		}
@@ -181,16 +187,16 @@ func (r *AuthenticationReader) readInternal(soft bool, mb *buf.MultiBuffer) erro
 		return nil
 	}
 
-	payload := bytespool.Alloc(int32(size))
+	payload := bytespool.Alloc(effectiveSize)
 	defer bytespool.Free(payload)
 
-	if _, err := io.ReadFull(r.reader, payload[:size]); err != nil {
+	if _, err := io.ReadFull(r.reader, payload[:effectiveSize]); err != nil {
 		return err
 	}
 
-	size -= padding
+	effectiveSize -= int32(padding)
 
-	rb, err := r.auth.Open(payload[:0], payload[:size])
+	rb, err := r.auth.Open(payload[:0], payload[:effectiveSize])
 	if err != nil {
 		return err
 	}

common/crypto/chunk.go

@@ -15,6 +15,13 @@ type ChunkSizeDecoder interface {
 	Decode([]byte) (uint16, error)
 }
 
+type ChunkSizeDecoderWithOffset interface {
+	ChunkSizeDecoder
+	// HasConstantOffset set the constant offset of Decode
+	// The effective size should be HasConstantOffset() + Decode(_).[0](uint64)
+	HasConstantOffset() uint16
+}
+
 // ChunkSizeEncoder is a utility class to encode size value into bytes.
 type ChunkSizeEncoder interface {
 	SizeBytes() int32

go.mod

@@ -17,6 +17,7 @@ require (
 	github.com/miekg/dns v1.1.57
 	github.com/mustafaturan/bus v1.0.2
 	github.com/pelletier/go-toml v1.9.5
+	github.com/pion/transport/v2 v2.2.1
 	github.com/pires/go-proxyproto v0.7.0
 	github.com/quic-go/quic-go v0.40.0
 	github.com/refraction-networking/utls v1.5.4
@@ -68,7 +69,6 @@ require (
 	github.com/pion/logging v0.2.2 // indirect
 	github.com/pion/randutil v0.1.0 // indirect
 	github.com/pion/sctp v1.8.7 // indirect
-	github.com/pion/transport/v2 v2.2.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/quic-go/qtls-go1-20 v0.4.1 // indirect
 	github.com/riobard/go-bloom v0.0.0-20200614022211-cdc8013cb5b3 // indirect

infra/conf/v5cfg/outbound.go

@@ -2,6 +2,7 @@ package v5cfg
 
 import (
 	"context"
+
 	"github.com/golang/protobuf/proto"
 
 	core "github.com/v2fly/v2ray-core/v5"

proxy/shadowsocks2022/client.go

@@ -111,7 +111,7 @@ func (c *Client) Process(ctx context.Context, link *transport.Link, dialer inter
 		if err != nil {
 			return newError("failed to find an available destination").AtWarning().Base(err)
 		}
-		newError("tunneling request to ", destination, " via ", network, ":", c.config.Address).WriteToLog(session.ExportIDToError(ctx))
+		newError("tunneling request to ", destination, " via ", network, ":", net.TCPDestination(c.config.Address.AsAddress(), net.Port(c.config.Port)).NetAddr()).WriteToLog(session.ExportIDToError(ctx))
 		defer conn.Close()
 
 		request := &TCPRequest{

proxy/shadowsocks2022/client_session.go

@@ -11,14 +11,17 @@ import (
 	"github.com/v2fly/v2ray-core/v5/common/buf"
 	"github.com/v2fly/v2ray-core/v5/common/net"
 	"github.com/v2fly/v2ray-core/v5/transport/internet"
+
+	"github.com/pion/transport/v2/replaydetector"
 )
 
 func NewClientUDPSession(ctx context.Context, conn io.ReadWriteCloser, packetProcessor UDPClientPacketProcessor) *ClientUDPSession {
 	session := &ClientUDPSession{
-		locker:          &sync.Mutex{},
+		locker:          &sync.RWMutex{},
 		conn:            conn,
 		packetProcessor: packetProcessor,
 		sessionMap:      make(map[string]*ClientUDPSessionConn),
+		sessionMapAlias: make(map[string]string),
 	}
 	session.ctx, session.finish = context.WithCancel(ctx)
 
@@ -27,16 +30,87 @@ func NewClientUDPSession(ctx context.Context, conn io.ReadWriteCloser, packetPro
 }
 
 type ClientUDPSession struct {
-	locker *sync.Mutex
+	locker *sync.RWMutex
 
 	conn            io.ReadWriteCloser
 	packetProcessor UDPClientPacketProcessor
 	sessionMap      map[string]*ClientUDPSessionConn
 
+	sessionMapAlias map[string]string
+
 	ctx    context.Context
 	finish func()
 }
 
+func (c *ClientUDPSession) GetCachedState(sessionID string) UDPClientPacketProcessorCachedState {
+	c.locker.RLock()
+	defer c.locker.RUnlock()
+
+	state, ok := c.sessionMap[sessionID]
+	if !ok {
+		return nil
+	}
+	return state.cachedProcessorState
+}
+
+func (c *ClientUDPSession) GetCachedServerState(serverSessionID string) UDPClientPacketProcessorCachedState {
+	c.locker.RLock()
+	defer c.locker.RUnlock()
+
+	clientSessionID := c.getCachedStateAlias(serverSessionID)
+	if clientSessionID == "" {
+		return nil
+	}
+	state, ok := c.sessionMap[clientSessionID]
+	if !ok {
+		return nil
+	}
+
+	if serverState, ok := state.trackedServerSessionID[serverSessionID]; !ok {
+		return nil
+	} else {
+		return serverState.cachedRecvProcessorState
+	}
+}
+
+func (c *ClientUDPSession) getCachedStateAlias(serverSessionID string) string {
+	state, ok := c.sessionMapAlias[serverSessionID]
+	if !ok {
+		return ""
+	}
+	return state
+}
+
+func (c *ClientUDPSession) PutCachedState(sessionID string, cache UDPClientPacketProcessorCachedState) {
+	c.locker.RLock()
+	defer c.locker.RUnlock()
+
+	state, ok := c.sessionMap[sessionID]
+	if !ok {
+		return
+	}
+	state.cachedProcessorState = cache
+}
+
+func (c *ClientUDPSession) PutCachedServerState(serverSessionID string, cache UDPClientPacketProcessorCachedState) {
+	c.locker.RLock()
+	defer c.locker.RUnlock()
+
+	clientSessionID := c.getCachedStateAlias(serverSessionID)
+	if clientSessionID == "" {
+		return
+	}
+	state, ok := c.sessionMap[clientSessionID]
+	if !ok {
+		return
+	}
+
+	if serverState, ok := state.trackedServerSessionID[serverSessionID]; ok {
+		serverState.cachedRecvProcessorState = cache
+		return
+	}
+}
+
 func (c *ClientUDPSession) Close() error {
 	c.finish()
 	return c.conn.Close()
@@ -45,7 +119,7 @@ func (c *ClientUDPSession) Close() error {
 func (c *ClientUDPSession) WriteUDPRequest(request *UDPRequest) error {
 	buffer := buf.New()
 	defer buffer.Release()
-	err := c.packetProcessor.EncodeUDPRequest(request, buffer)
+	err := c.packetProcessor.EncodeUDPRequest(request, buffer, c)
 	if request.Payload != nil {
 		request.Payload.Release()
 	}
@@ -69,7 +143,7 @@ func (c *ClientUDPSession) KeepReading() {
 			return
 		}
 		if n != 0 {
-			err := c.packetProcessor.DecodeUDPResp(buffer[:n], udpResp)
+			err := c.packetProcessor.DecodeUDPResp(buffer[:n], udpResp, c)
 			if err != nil {
 				newError("unable to decode udp response").Base(err).WriteToLog()
 				continue
@@ -78,13 +152,14 @@ func (c *ClientUDPSession) KeepReading() {
 			{
 				timeDifference := int64(udpResp.TimeStamp) - time.Now().Unix()
 				if timeDifference < -30 || timeDifference > 30 {
-					newError("udp packet timestamp difference too large, packet discarded").WriteToLog()
+					newError("udp packet timestamp difference too large, packet discarded, time diff = ", timeDifference).WriteToLog()
 					continue
 				}
 			}
 
-			c.locker.Lock()
+			c.locker.RLock()
 			session, ok := c.sessionMap[string(udpResp.ClientSessionID[:])]
+			c.locker.RUnlock()
 			if ok {
 				select {
 				case session.readChan <- udpResp:
@@ -93,7 +168,6 @@ func (c *ClientUDPSession) KeepReading() {
 			} else {
 				newError("misbehaving server: unknown client session ID").Base(err).WriteToLog()
 			}
-			c.locker.Unlock()
 		}
 	}
 }
@@ -108,12 +182,13 @@ func (c *ClientUDPSession) NewSessionConn() (internet.AbstractPacketConn, error)
 	connctx, connfinish := context.WithCancel(c.ctx)
 
 	sessionConn := &ClientUDPSessionConn{
-		sessionID:         string(sessionID),
-		readChan:          make(chan *UDPResponse, 16),
-		parent:            c,
-		ctx:               connctx,
-		finish:            connfinish,
-		nextWritePacketID: 0,
+		sessionID:              string(sessionID),
+		readChan:               make(chan *UDPResponse, 128),
+		parent:                 c,
+		ctx:                    connctx,
+		finish:                 connfinish,
+		nextWritePacketID:      0,
+		trackedServerSessionID: make(map[string]*ClientUDPSessionServerTracker),
 	}
 	c.locker.Lock()
 	c.sessionMap[sessionConn.sessionID] = sessionConn
@@ -121,19 +196,33 @@ func (c *ClientUDPSession) NewSessionConn() (internet.AbstractPacketConn, error)
 	return sessionConn, nil
 }
 
+type ClientUDPSessionServerTracker struct {
+	cachedRecvProcessorState UDPClientPacketProcessorCachedState
+	rxReplayDetector         replaydetector.ReplayDetector
+	lastSeen                 time.Time
+}
+
 type ClientUDPSessionConn struct {
 	sessionID string
 	readChan  chan *UDPResponse
 	parent    *ClientUDPSession
 
-	nextWritePacketID uint64
+	nextWritePacketID      uint64
+	trackedServerSessionID map[string]*ClientUDPSessionServerTracker
+
+	cachedProcessorState UDPClientPacketProcessorCachedState
 
 	ctx    context.Context
 	finish func()
 }
 
 func (c *ClientUDPSessionConn) Close() error {
+	c.parent.locker.Lock()
 	delete(c.parent.sessionMap, c.sessionID)
+	for k := range c.trackedServerSessionID {
+		delete(c.parent.sessionMapAlias, k)
+	}
+	c.parent.locker.Unlock()
 	c.finish()
 	return nil
 }
@@ -160,13 +249,44 @@ func (c *ClientUDPSessionConn) WriteTo(p []byte, addr gonet.Addr) (n int, err er
 }
 
 func (c *ClientUDPSessionConn) ReadFrom(p []byte) (n int, addr net.Addr, err error) {
-	select {
-	case <-c.ctx.Done():
-		return 0, nil, io.EOF
-	case resp := <-c.readChan:
-		n = copy(p, resp.Payload.Bytes())
-		resp.Payload.Release()
-		addr = &net.UDPAddr{IP: resp.Address.IP(), Port: resp.Port}
-	}
-	return
+	for {
+		select {
+		case <-c.ctx.Done():
+			return 0, nil, io.EOF
+		case resp := <-c.readChan:
+			n = copy(p, resp.Payload.Bytes())
+			resp.Payload.Release()
+
+			var trackedState *ClientUDPSessionServerTracker
+			if trackedStateReceived, ok := c.trackedServerSessionID[string(resp.SessionID[:])]; !ok {
+				for key, value := range c.trackedServerSessionID {
+					if time.Since(value.lastSeen) > 65*time.Second {
+						delete(c.trackedServerSessionID, key)
+					}
+				}
+
+				state := &ClientUDPSessionServerTracker{
+					rxReplayDetector: replaydetector.New(1024, ^uint64(0)),
+				}
+				c.trackedServerSessionID[string(resp.SessionID[:])] = state
+				c.parent.locker.RLock()
+				c.parent.sessionMapAlias[string(resp.SessionID[:])] = string(resp.ClientSessionID[:])
+				c.parent.locker.RUnlock()
+				trackedState = state
+			} else {
+				trackedState = trackedStateReceived
+			}
+
+			if accept, ok := trackedState.rxReplayDetector.Check(resp.PacketID); ok {
+				accept()
+			} else {
+				newError("misbehaving server: replayed packet").Base(err).WriteToLog()
+				continue
+			}
+			trackedState.lastSeen = time.Now()
+
+			addr = &net.UDPAddr{IP: resp.Address.IP(), Port: resp.Port}
+		}
+		return n, addr, nil
+	}
 }

proxy/shadowsocks2022/encoding.go

@@ -4,10 +4,13 @@ import (
 	"bytes"
 	"crypto/cipher"
 	cryptoRand "crypto/rand"
+	"encoding/binary"
 	"io"
 	"math/rand"
 	"time"
 
+	"github.com/v2fly/v2ray-core/v5/common"
+
 	"github.com/lunixbochs/struc"
 
 	"github.com/v2fly/v2ray-core/v5/common/buf"
@@ -59,7 +62,7 @@ func (t *TCPRequest) EncodeTCPRequestHeader(effectivePsk []byte,
 	paddingLength := TCPMinPaddingLength
 	if initialPayload == nil {
 		initialPayload = []byte{}
-		paddingLength += rand.Intn(TCPMaxPaddingLength) // TODO INSECURE RANDOM USED
+		paddingLength += 1 + rand.Intn(TCPMaxPaddingLength) // TODO INSECURE RANDOM USED
 	}
 
 	variableLengthHeader := &TCPRequestHeader3VariableLength{
@@ -110,10 +113,14 @@ func (t *TCPRequest) EncodeTCPRequestHeader(effectivePsk []byte,
 			return newError("failed to pack fixed length header").Base(err)
 		}
 	}
-	eihGenerator := newAESEIHGeneratorContainer(len(eih), effectivePsk, eih)
-	eihHeader, err := eihGenerator.GenerateEIH(t.keyDerivation, t.method, requestSalt.Bytes())
-	if err != nil {
-		return newError("failed to construct EIH").Base(err)
+	eihHeader := ExtensibleIdentityHeaders(newAESEIH(0))
+	if len(eih) != 0 {
+		eihGenerator := newAESEIHGeneratorContainer(len(eih), effectivePsk, eih)
+		eihHeaderGenerated, err := eihGenerator.GenerateEIH(t.keyDerivation, t.method, requestSalt.Bytes())
+		if err != nil {
+			return newError("failed to construct EIH").Base(err)
+		}
+		eihHeader = eihHeaderGenerated
 	}
 	preSessionKeyHeader := &TCPRequestHeader1PreSessionKey{
 		Salt: requestSalt,
@@ -206,7 +213,7 @@ func (t *TCPRequest) DecodeTCPResponseHeader(effectivePsk []byte, in io.Reader)
 	}
 	timeDifference := int64(fixedLengthHeader.Timestamp) - time.Now().Unix()
 	if timeDifference < -30 || timeDifference > 30 {
-		return newError("timestamp is too far away")
+		return newError("timestamp is too far away, timeDifference = ", timeDifference)
 	}
 
 	t.s2cSaltAssert = fixedLengthHeader.RequestSalt
@@ -239,7 +246,7 @@ func (t *TCPRequest) CreateClientS2CReader(in io.Reader, initialPayload *buf.Buf
 	if err != nil {
 		return nil, newError("failed to decrypt initial payload").Base(err)
 	}
-	return crypto.NewAuthenticationReader(AEADAuthenticator, &crypto.AEADChunkSizeParser{
+	return crypto.NewAuthenticationReader(AEADAuthenticator, &AEADChunkSizeParser{
 		Auth: AEADAuthenticator,
 	}, in, protocol.TransferTypeStream, nil), nil
 }
@@ -255,3 +262,30 @@ func (t *TCPRequest) CreateClientC2SWriter(writer io.Writer) buf.Writer {
 	}
 	return crypto.NewAuthenticationWriter(AEADAuthenticator, sizeParser, writer, protocol.TransferTypeStream, nil)
 }
+
+type AEADChunkSizeParser struct {
+	Auth *crypto.AEADAuthenticator
+}
+
+func (p *AEADChunkSizeParser) HasConstantOffset() uint16 {
+	return uint16(p.Auth.Overhead())
+}
+
+func (p *AEADChunkSizeParser) SizeBytes() int32 {
+	return 2 + int32(p.Auth.Overhead())
+}
+
+func (p *AEADChunkSizeParser) Encode(size uint16, b []byte) []byte {
+	binary.BigEndian.PutUint16(b, size-uint16(p.Auth.Overhead()))
+	b, err := p.Auth.Seal(b[:0], b[:2])
+	common.Must(err)
+	return b
+}
+
+func (p *AEADChunkSizeParser) Decode(b []byte) (uint16, error) {
+	b, err := p.Auth.Open(b[:0], b)
+	if err != nil {
+		return 0, err
+	}
+	return binary.BigEndian.Uint16(b), nil
+}

proxy/shadowsocks2022/ss2022.go

@@ -112,9 +112,18 @@ const (
 	UDPHeaderTypeServerToClientStream = byte(0x01)
 )
 
+type UDPClientPacketProcessorCachedStateContainer interface {
+	GetCachedState(sessionID string) UDPClientPacketProcessorCachedState
+	PutCachedState(sessionID string, cache UDPClientPacketProcessorCachedState)
+	GetCachedServerState(serverSessionID string) UDPClientPacketProcessorCachedState
+	PutCachedServerState(serverSessionID string, cache UDPClientPacketProcessorCachedState)
+}
+
+type UDPClientPacketProcessorCachedState interface{}
+
 // UDPClientPacketProcessor
 // Caller retain and receive all ownership of the buffer
 type UDPClientPacketProcessor interface {
-	EncodeUDPRequest(request *UDPRequest, out *buf.Buffer) error
-	DecodeUDPResp(input []byte, resp *UDPResponse) error
+	EncodeUDPRequest(request *UDPRequest, out *buf.Buffer, cache UDPClientPacketProcessorCachedStateContainer) error
+	DecodeUDPResp(input []byte, resp *UDPResponse, cache UDPClientPacketProcessorCachedStateContainer) error
 }

proxy/shadowsocks2022/udp_aes.go

@@ -47,7 +47,14 @@ type respHeader struct {
 	Padding         []byte
 }
 
-func (p *AESUDPClientPacketProcessor) EncodeUDPRequest(request *UDPRequest, out *buf.Buffer) error {
+type cachedUDPState struct {
+	sessionAEAD     cipher.AEAD
+	sessionRecvAEAD cipher.AEAD
+}
+
+func (p *AESUDPClientPacketProcessor) EncodeUDPRequest(request *UDPRequest, out *buf.Buffer,
+	cache UDPClientPacketProcessorCachedStateContainer,
+) error {
 	separateHeaderStruct := separateHeader{PacketID: request.PacketID, SessionID: request.SessionID}
 	separateHeaderBuffer := buf.New()
 	defer separateHeaderBuffer.Release()
@@ -102,14 +109,28 @@ func (p *AESUDPClientPacketProcessor) EncodeUDPRequest(request *UDPRequest, out
 		}
 	}
 	{
-		mainPacketAEADMaterialized := p.mainPacketAEAD(separateHeaderBufferBytes[0:8])
+		cacheKey := string(separateHeaderBufferBytes[0:8])
+		receivedCacheInterface := cache.GetCachedState(cacheKey)
+		cachedState := &cachedUDPState{}
+		if receivedCacheInterface != nil {
+			cachedState = receivedCacheInterface.(*cachedUDPState)
+		}
+		if cachedState.sessionAEAD == nil {
+			cachedState.sessionAEAD = p.mainPacketAEAD(separateHeaderBufferBytes[0:8])
+			cache.PutCachedState(cacheKey, cachedState)
+		}
+
+		mainPacketAEADMaterialized := cachedState.sessionAEAD
+
 		encryptedDest := out.Extend(int32(mainPacketAEADMaterialized.Overhead()) + requestBodyBuffer.Len())
 		mainPacketAEADMaterialized.Seal(encryptedDest[:0], separateHeaderBuffer.Bytes()[4:16], requestBodyBuffer.Bytes(), nil)
 	}
 	return nil
 }
 
-func (p *AESUDPClientPacketProcessor) DecodeUDPResp(input []byte, resp *UDPResponse) error {
+func (p *AESUDPClientPacketProcessor) DecodeUDPResp(input []byte, resp *UDPResponse,
+	cache UDPClientPacketProcessorCachedStateContainer,
+) error {
 	separateHeaderBuffer := buf.New()
 	defer separateHeaderBuffer.Release()
 	{
@@ -126,7 +147,19 @@ func (p *AESUDPClientPacketProcessor) DecodeUDPResp(input []byte, resp *UDPRespo
 	resp.PacketID = separateHeaderStruct.PacketID
 	resp.SessionID = separateHeaderStruct.SessionID
 	{
-		mainPacketAEADMaterialized := p.mainPacketAEAD(separateHeaderBuffer.Bytes()[0:8])
+		cacheKey := string(separateHeaderBuffer.Bytes()[0:8])
+		receivedCacheInterface := cache.GetCachedServerState(cacheKey)
+		cachedState := &cachedUDPState{}
+		if receivedCacheInterface != nil {
+			cachedState = receivedCacheInterface.(*cachedUDPState)
+		}
+
+		if cachedState.sessionRecvAEAD == nil {
+			cachedState.sessionRecvAEAD = p.mainPacketAEAD(separateHeaderBuffer.Bytes()[0:8])
+			cache.PutCachedServerState(cacheKey, cachedState)
+		}
+
+		mainPacketAEADMaterialized := cachedState.sessionRecvAEAD
 		decryptedDestBuffer := buf.New()
 		decryptedDest := decryptedDestBuffer.Extend(int32(len(input)) - 16 - int32(mainPacketAEADMaterialized.Overhead()))
 		_, err := mainPacketAEADMaterialized.Open(decryptedDest[:0], separateHeaderBuffer.Bytes()[4:16], input[16:], nil)