Refactor: Fragmentation

https://github.com/XTLS/Xray-core/commit/5f5ae375714abd67eb2f0a0f2e86410b6f29f7c2
https://github.com/XTLS/Xray-core/commit/9122d0f056ed5b0e6fc9b290fdc7b39f47b49a39

infra/conf/freedom.go

@@ -39,91 +39,89 @@ func (c *FreedomConfig) Build() (proto.Message, error) {
 	}
 
 	if c.Fragment != nil {
-		if len(c.Fragment.Interval) == 0 || len(c.Fragment.Length) == 0 {
-			return nil, newError("Invalid interval or length")
-		}
-		intervalMinMax := strings.Split(c.Fragment.Interval, "-")
-		var minInterval, maxInterval int64
+		config.Fragment = new(freedom.Fragment)
 		var err, err2 error
-		if len(intervalMinMax) == 2 {
-			minInterval, err = strconv.ParseInt(intervalMinMax[0], 10, 64)
-			maxInterval, err2 = strconv.ParseInt(intervalMinMax[1], 10, 64)
-		} else {
-			minInterval, err = strconv.ParseInt(intervalMinMax[0], 10, 64)
-			maxInterval = minInterval
-		}
-		if err != nil {
-			return nil, newError("Invalid minimum interval: ", err).Base(err)
-		}
-		if err2 != nil {
-			return nil, newError("Invalid maximum interval: ", err2).Base(err2)
-		}
-
-		lengthMinMax := strings.Split(c.Fragment.Length, "-")
-		var minLength, maxLength int64
-		if len(lengthMinMax) == 2 {
-			minLength, err = strconv.ParseInt(lengthMinMax[0], 10, 64)
-			maxLength, err2 = strconv.ParseInt(lengthMinMax[1], 10, 64)
-
-		} else {
-			minLength, err = strconv.ParseInt(lengthMinMax[0], 10, 64)
-			maxLength = minLength
-		}
-		if err != nil {
-			return nil, newError("Invalid minimum length: ", err).Base(err)
-		}
-		if err2 != nil {
-			return nil, newError("Invalid maximum length: ", err2).Base(err2)
-		}
-
-		if minInterval > maxInterval {
-			minInterval, maxInterval = maxInterval, minInterval
-		}
-		if minLength > maxLength {
-			minLength, maxLength = maxLength, minLength
-		}
-
-		config.Fragment = &freedom.Fragment{
-			MinInterval: int32(minInterval),
-			MaxInterval: int32(maxInterval),
-			MinLength:   int32(minLength),
-			MaxLength:   int32(maxLength),
-		}
 
 		switch strings.ToLower(c.Fragment.Packets) {
 		case "tlshello":
 			// TLS Hello Fragmentation (into multiple handshake messages)
-			config.Fragment.StartPacket = 0
-			config.Fragment.EndPacket = 1
+			config.Fragment.PacketsFrom = 0
+			config.Fragment.PacketsTo = 1
 		case "":
 			// TCP Segmentation (all packets)
-			config.Fragment.StartPacket = 0
-			config.Fragment.EndPacket = 0
+			config.Fragment.PacketsFrom = 0
+			config.Fragment.PacketsTo = 0
 		default:
 			// TCP Segmentation (range)
-			packetRange := strings.Split(c.Fragment.Packets, "-")
-			var startPacket, endPacket int64
-			if len(packetRange) == 2 {
-				startPacket, err = strconv.ParseInt(packetRange[0], 10, 64)
-				endPacket, err2 = strconv.ParseInt(packetRange[1], 10, 64)
+			packetsFromTo := strings.Split(c.Fragment.Packets, "-")
+			if len(packetsFromTo) == 2 {
+				config.Fragment.PacketsFrom, err = strconv.ParseUint(packetsFromTo[0], 10, 64)
+				config.Fragment.PacketsTo, err2 = strconv.ParseUint(packetsFromTo[1], 10, 64)
 			} else {
-				startPacket, err = strconv.ParseInt(packetRange[0], 10, 64)
-				endPacket = startPacket
+				config.Fragment.PacketsFrom, err = strconv.ParseUint(packetsFromTo[0], 10, 64)
+				config.Fragment.PacketsTo = config.Fragment.PacketsFrom
 			}
 			if err != nil {
-				return nil, newError("Invalid start packet: ", err).Base(err)
+				return nil, newError("Invalid PacketsFrom").Base(err)
 			}
 			if err2 != nil {
-				return nil, newError("Invalid end packet: ", err2).Base(err2)
+				return nil, newError("Invalid PacketsTo").Base(err2)
+			}
+			if config.Fragment.PacketsFrom > config.Fragment.PacketsTo {
+				config.Fragment.PacketsFrom, config.Fragment.PacketsTo = config.Fragment.PacketsTo, config.Fragment.PacketsFrom
 			}
-			if startPacket > endPacket {
-				return nil, newError("Invalid packet range: ", c.Fragment.Packets)
+			if config.Fragment.PacketsFrom == 0 {
+				return nil, newError("PacketsFrom can't be 0")
+			}
+		}
+
+		{
+			if c.Fragment.Length == "" {
+				return nil, newError("Length can't be empty")
+			}
+			lengthMinMax := strings.Split(c.Fragment.Length, "-")
+			if len(lengthMinMax) == 2 {
+				config.Fragment.LengthMin, err = strconv.ParseUint(lengthMinMax[0], 10, 64)
+				config.Fragment.LengthMax, err2 = strconv.ParseUint(lengthMinMax[1], 10, 64)
+			} else {
+				config.Fragment.LengthMin, err = strconv.ParseUint(lengthMinMax[0], 10, 64)
+				config.Fragment.LengthMax = config.Fragment.LengthMin
+			}
+			if err != nil {
+				return nil, newError("Invalid LengthMin").Base(err)
+			}
+			if err2 != nil {
+				return nil, newError("Invalid LengthMax").Base(err2)
+			}
+			if config.Fragment.LengthMin > config.Fragment.LengthMax {
+				config.Fragment.LengthMin, config.Fragment.LengthMax = config.Fragment.LengthMax, config.Fragment.LengthMin
+			}
+			if config.Fragment.LengthMin == 0 {
+				return nil, newError("LengthMin can't be 0")
+			}
+		}
+
+		{
+			if c.Fragment.Interval == "" {
+				return nil, newError("Interval can't be empty")
+			}
+			intervalMinMax := strings.Split(c.Fragment.Interval, "-")
+			if len(intervalMinMax) == 2 {
+				config.Fragment.IntervalMin, err = strconv.ParseUint(intervalMinMax[0], 10, 64)
+				config.Fragment.IntervalMax, err2 = strconv.ParseUint(intervalMinMax[1], 10, 64)
+			} else {
+				config.Fragment.IntervalMin, err = strconv.ParseUint(intervalMinMax[0], 10, 64)
+				config.Fragment.IntervalMax = config.Fragment.IntervalMin
+			}
+			if err != nil {
+				return nil, newError("Invalid IntervalMin").Base(err)
+			}
+			if err2 != nil {
+				return nil, newError("Invalid IntervalMax").Base(err2)
 			}
-			if startPacket < 1 {
-				return nil, newError("Cannot start from packet 0")
+			if config.Fragment.IntervalMin > config.Fragment.IntervalMax {
+				config.Fragment.IntervalMin, config.Fragment.IntervalMax = config.Fragment.IntervalMax, config.Fragment.IntervalMin
 			}
-			config.Fragment.StartPacket = int32(startPacket)
-			config.Fragment.EndPacket = int32(endPacket)
 		}
 	}
 

proxy/freedom/config.pb.go

@@ -125,12 +125,12 @@ type Fragment struct {
 	sizeCache     protoimpl.SizeCache
 	unknownFields protoimpl.UnknownFields
 
-	MinInterval int32 `protobuf:"varint,1,opt,name=min_interval,json=minInterval,proto3" json:"min_interval,omitempty"`
-	MaxInterval int32 `protobuf:"varint,2,opt,name=max_interval,json=maxInterval,proto3" json:"max_interval,omitempty"`
-	MinLength   int32 `protobuf:"varint,3,opt,name=min_length,json=minLength,proto3" json:"min_length,omitempty"`
-	MaxLength   int32 `protobuf:"varint,4,opt,name=max_length,json=maxLength,proto3" json:"max_length,omitempty"`
-	StartPacket int32 `protobuf:"varint,5,opt,name=start_packet,json=startPacket,proto3" json:"start_packet,omitempty"`
-	EndPacket   int32 `protobuf:"varint,6,opt,name=end_packet,json=endPacket,proto3" json:"end_packet,omitempty"`
+	PacketsFrom uint64 `protobuf:"varint,1,opt,name=packets_from,json=packetsFrom,proto3" json:"packets_from,omitempty"`
+	PacketsTo   uint64 `protobuf:"varint,2,opt,name=packets_to,json=packetsTo,proto3" json:"packets_to,omitempty"`
+	LengthMin   uint64 `protobuf:"varint,3,opt,name=length_min,json=lengthMin,proto3" json:"length_min,omitempty"`
+	LengthMax   uint64 `protobuf:"varint,4,opt,name=length_max,json=lengthMax,proto3" json:"length_max,omitempty"`
+	IntervalMin uint64 `protobuf:"varint,5,opt,name=interval_min,json=intervalMin,proto3" json:"interval_min,omitempty"`
+	IntervalMax uint64 `protobuf:"varint,6,opt,name=interval_max,json=intervalMax,proto3" json:"interval_max,omitempty"`
 }
 
 func (x *Fragment) Reset() {
@@ -165,44 +165,44 @@ func (*Fragment) Descriptor() ([]byte, []int) {
 	return file_proxy_freedom_config_proto_rawDescGZIP(), []int{1}
 }
 
-func (x *Fragment) GetMinInterval() int32 {
+func (x *Fragment) GetPacketsFrom() uint64 {
 	if x != nil {
-		return x.MinInterval
+		return x.PacketsFrom
 	}
 	return 0
 }
 
-func (x *Fragment) GetMaxInterval() int32 {
+func (x *Fragment) GetPacketsTo() uint64 {
 	if x != nil {
-		return x.MaxInterval
+		return x.PacketsTo
 	}
 	return 0
 }
 
-func (x *Fragment) GetMinLength() int32 {
+func (x *Fragment) GetLengthMin() uint64 {
 	if x != nil {
-		return x.MinLength
+		return x.LengthMin
 	}
 	return 0
 }
 
-func (x *Fragment) GetMaxLength() int32 {
+func (x *Fragment) GetLengthMax() uint64 {
 	if x != nil {
-		return x.MaxLength
+		return x.LengthMax
 	}
 	return 0
 }
 
-func (x *Fragment) GetStartPacket() int32 {
+func (x *Fragment) GetIntervalMin() uint64 {
 	if x != nil {
-		return x.StartPacket
+		return x.IntervalMin
 	}
 	return 0
 }
 
-func (x *Fragment) GetEndPacket() int32 {
+func (x *Fragment) GetIntervalMax() uint64 {
 	if x != nil {
-		return x.EndPacket
+		return x.IntervalMax
 	}
 	return 0
 }
@@ -302,19 +302,19 @@ var file_proxy_freedom_config_proto_rawDesc = []byte{
 	0x79, 0x2e, 0x63, 0x6f, 0x6d, 0x6d, 0x6f, 0x6e, 0x2e, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x63, 0x6f,
 	0x6c, 0x2e, 0x53, 0x65, 0x72, 0x76, 0x65, 0x72, 0x45, 0x6e, 0x64, 0x70, 0x6f, 0x69, 0x6e, 0x74,
 	0x52, 0x06, 0x73, 0x65, 0x72, 0x76, 0x65, 0x72, 0x22, 0xd0, 0x01, 0x0a, 0x08, 0x46, 0x72, 0x61,
-	0x67, 0x6d, 0x65, 0x6e, 0x74, 0x12, 0x21, 0x0a, 0x0c, 0x6d, 0x69, 0x6e, 0x5f, 0x69, 0x6e, 0x74,
-	0x65, 0x72, 0x76, 0x61, 0x6c, 0x18, 0x01, 0x20, 0x01, 0x28, 0x05, 0x52, 0x0b, 0x6d, 0x69, 0x6e,
-	0x49, 0x6e, 0x74, 0x65, 0x72, 0x76, 0x61, 0x6c, 0x12, 0x21, 0x0a, 0x0c, 0x6d, 0x61, 0x78, 0x5f,
-	0x69, 0x6e, 0x74, 0x65, 0x72, 0x76, 0x61, 0x6c, 0x18, 0x02, 0x20, 0x01, 0x28, 0x05, 0x52, 0x0b,
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proxy/freedom/config.proto

@@ -13,12 +13,12 @@ message DestinationOverride {
 }
 
 message Fragment {
-  int32 min_interval = 1;
-  int32 max_interval = 2;
-  int32 min_length = 3;
-  int32 max_length = 4;
-  int32 start_packet = 5;
-  int32 end_packet = 6;
+  uint64 packets_from = 1;
+  uint64 packets_to = 2;
+  uint64 length_min = 3;
+  uint64 length_max = 4;
+  uint64 interval_min = 5;
+  uint64 interval_max = 6;
 }
 
 message Config {

proxy/freedom/freedom.go

@@ -5,7 +5,6 @@ package freedom
 import (
 	"context"
 	"crypto/rand"
-	"encoding/binary"
 	"io"
 	"math/big"
 	"time"
@@ -13,7 +12,6 @@ import (
 	"github.com/xtls/xray-core/common"
 	"github.com/xtls/xray-core/common/buf"
 	"github.com/xtls/xray-core/common/dice"
-	"github.com/xtls/xray-core/common/errors"
 	"github.com/xtls/xray-core/common/net"
 	"github.com/xtls/xray-core/common/retry"
 	"github.com/xtls/xray-core/common/session"
@@ -175,28 +173,12 @@ func (h *Handler) Process(ctx context.Context, link *transport.Link, dialer inte
 		var writer buf.Writer
 		if destination.Network == net.Network_TCP {
 			if h.config.Fragment != nil {
-				if h.config.Fragment.StartPacket == 0 && h.config.Fragment.EndPacket == 1 {
-					newError("FRAGMENT", int(h.config.Fragment.MaxLength)).WriteToLog(session.ExportIDToError(ctx))
-					writer = buf.NewWriter(
-						&FragmentedClientHelloConn{
-							Conn:        conn,
-							maxLength:   int(h.config.Fragment.MaxLength),
-							minInterval: time.Duration(h.config.Fragment.MinInterval) * time.Millisecond,
-							maxInterval: time.Duration(h.config.Fragment.MaxInterval) * time.Millisecond,
-						})
-				} else {
-					writer = buf.NewWriter(
-						&FragmentWriter{
-							Writer:      conn,
-							minLength:   int(h.config.Fragment.MinLength),
-							maxLength:   int(h.config.Fragment.MaxLength),
-							minInterval: time.Duration(h.config.Fragment.MinInterval) * time.Millisecond,
-							maxInterval: time.Duration(h.config.Fragment.MaxInterval) * time.Millisecond,
-							startPacket: int(h.config.Fragment.StartPacket),
-							endPacket:   int(h.config.Fragment.EndPacket),
-							PacketCount: 0,
-						})
-				}
+				newError("FRAGMENT", h.config.Fragment.PacketsFrom, h.config.Fragment.PacketsTo, h.config.Fragment.LengthMin, h.config.Fragment.LengthMax,
+					h.config.Fragment.IntervalMin, h.config.Fragment.IntervalMax).AtDebug().WriteToLog(session.ExportIDToError(ctx))
+				writer = buf.NewWriter(&FragmentWriter{
+					fragment: h.config.Fragment,
+					writer:   conn,
+				})
 			} else {
 				writer = buf.NewWriter(conn)
 			}
@@ -356,40 +338,66 @@ func (w *PacketWriter) WriteMultiBuffer(mb buf.MultiBuffer) error {
 }
 
 type FragmentWriter struct {
-	io.Writer
-	minLength   int
-	maxLength   int
-	minInterval time.Duration
-	maxInterval time.Duration
-	startPacket int
-	endPacket   int
-	PacketCount int
+	fragment *Fragment
+	writer   io.Writer
+	count    uint64
 }
 
-func (w *FragmentWriter) Write(buf []byte) (int, error) {
-	w.PacketCount += 1
-	if (w.startPacket != 0 && (w.PacketCount < w.startPacket || w.PacketCount > w.endPacket)) || len(buf) <= w.minLength {
-		return w.Writer.Write(buf)
+func (f *FragmentWriter) Write(b []byte) (int, error) {
+	f.count++
+
+	if f.fragment.PacketsFrom == 0 && f.fragment.PacketsTo == 1 {
+		if f.count != 1 || len(b) <= 5 || b[0] != 22 {
+			return f.writer.Write(b)
+		}
+		recordLen := 5 + ((int(b[3]) << 8) | int(b[4]))
+		data := b[5:recordLen]
+		buf := make([]byte, 1024)
+		for from := 0; ; {
+			to := from + int(randBetween(int64(f.fragment.LengthMin), int64(f.fragment.LengthMax)))
+			if to > len(data) {
+				to = len(data)
+			}
+			copy(buf[:3], b)
+			copy(buf[5:], data[from:to])
+			l := to - from
+			from = to
+			buf[3] = byte(l >> 8)
+			buf[4] = byte(l)
+			_, err := f.writer.Write(buf[:5+l])
+			time.Sleep(time.Duration(randBetween(int64(f.fragment.IntervalMin), int64(f.fragment.IntervalMax))) * time.Millisecond)
+			if err != nil {
+				return 0, err
+			}
+			if from == len(data) {
+				if len(b) > recordLen {
+					n, err := f.writer.Write(b[recordLen:])
+					if err != nil {
+						return recordLen + n, err
+					}
+				}
+				return len(b), nil
+			}
+		}
 	}
 
-	nTotal := 0
-	for {
-		randomBytesTo := int(randBetween(int64(w.minLength), int64(w.maxLength))) + nTotal
-		if randomBytesTo > len(buf) {
-			randomBytesTo = len(buf)
+	if f.fragment.PacketsFrom != 0 && (f.count < f.fragment.PacketsFrom || f.count > f.fragment.PacketsTo) {
+		return f.writer.Write(b)
+	}
+	for from := 0; ; {
+		to := from + int(randBetween(int64(f.fragment.LengthMin), int64(f.fragment.LengthMax)))
+		if to > len(b) {
+			to = len(b)
 		}
-		n, err := w.Writer.Write(buf[nTotal:randomBytesTo])
+		n, err := f.writer.Write(b[from:to])
+		from += n
+		time.Sleep(time.Duration(randBetween(int64(f.fragment.IntervalMin), int64(f.fragment.IntervalMax))) * time.Millisecond)
 		if err != nil {
-			return nTotal + n, err
+			return from, err
 		}
-		nTotal += n
-
-		if nTotal >= len(buf) {
-			return nTotal, nil
+		if from >= len(b) {
+			return from, nil
 		}
-
-		randomInterval := randBetween(int64(w.minInterval), int64(w.maxInterval))
-		time.Sleep(time.Duration(randomInterval))
 	}
 }
 
@@ -401,66 +409,3 @@ func randBetween(left int64, right int64) int64 {
 	bigInt, _ := rand.Int(rand.Reader, big.NewInt(right-left))
 	return left + bigInt.Int64()
 }
-
-type FragmentedClientHelloConn struct {
-	net.Conn
-	PacketCount int
-	minLength   int
-	maxLength   int
-	minInterval time.Duration
-	maxInterval time.Duration
-}
-
-func (c *FragmentedClientHelloConn) Write(b []byte) (n int, err error) {
-	if len(b) >= 5 && b[0] == 22 && c.PacketCount == 0 {
-		n, err = sendFragmentedClientHello(c, b, c.minLength, c.maxLength)
-
-		if err == nil {
-			c.PacketCount++
-			return n, err
-		}
-	}
-
-	return c.Conn.Write(b)
-}
-
-func sendFragmentedClientHello(conn *FragmentedClientHelloConn, clientHello []byte, minFragmentSize, maxFragmentSize int) (n int, err error) {
-	if len(clientHello) < 5 || clientHello[0] != 22 {
-		return 0, errors.New("not a valid TLS ClientHello message")
-	}
-
-	clientHelloLen := (int(clientHello[3]) << 8) | int(clientHello[4])
-
-	clientHelloData := clientHello[5:]
-	for i := 0; i < clientHelloLen; {
-		fragmentEnd := i + int(randBetween(int64(minFragmentSize), int64(maxFragmentSize)))
-		if fragmentEnd > clientHelloLen {
-			fragmentEnd = clientHelloLen
-		}
-
-		fragment := clientHelloData[i:fragmentEnd]
-		i = fragmentEnd
-
-		err = writeFragmentedRecord(conn, 22, fragment, clientHello)
-		if err != nil {
-			return 0, err
-		}
-	}
-
-	return len(clientHello), nil
-}
-
-func writeFragmentedRecord(c *FragmentedClientHelloConn, contentType uint8, data []byte, clientHello []byte) error {
-	header := make([]byte, 5)
-	header[0] = byte(clientHello[0])
-
-	tlsVersion := (int(clientHello[1]) << 8) | int(clientHello[2])
-	binary.BigEndian.PutUint16(header[1:], uint16(tlsVersion))
-
-	binary.BigEndian.PutUint16(header[3:], uint16(len(data)))
-	_, err := c.Conn.Write(append(header, data...))
-	randomInterval := randBetween(int64(c.minInterval), int64(c.maxInterval))
-	time.Sleep(time.Duration(randomInterval))
-
-	return err
-}