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Refactor: Fragmentation

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9122d0f056
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RPRX 2023-07-06 16:30:39 +00:00 • committed by GitHub
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commit f0f3b417f7
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4 changed files with 161 additions and 218 deletions
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171
proxy/freedom/freedom.go
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@ -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
}