fix: xor

gold/link/crypto.go

@@ -66,23 +66,58 @@ func (l *Link) DecodePreshared(additional uint16, b []byte) (db []byte) {
 	return
 }
 
-// xor 按 8 字节, 以初始 m.mask 循环异或 data
-func (m *Me) xor(data []byte) []byte {
+// xorenc 按 8 字节, 以初始 m.mask 循环异或编码 data
+func (m *Me) xorenc(data []byte) []byte {
 	batchsz := len(data) / 8
 	remain := len(data) % 8
 	sum := m.mask
-	for i := 0; i < batchsz; i++ {
+	if remain > 0 {
+		var buf [8]byte
+		p := batchsz * 8
+		copy(buf[:], data[p:])
+		sum ^= binary.LittleEndian.Uint64(buf[:])
+		binary.LittleEndian.PutUint64(buf[:], sum)
+		copy(data[p:], buf[:])
+	}
+	for i := batchsz - 1; i >= 0; i-- {
 		a := i * 8
 		b := (i + 1) * 8
 		sum ^= binary.LittleEndian.Uint64(data[a:b])
 		binary.LittleEndian.PutUint64(data[a:b], sum)
 	}
+	return data
+}
+
+// xordec 按 8 字节, 以初始 m.mask 循环异或解码 data
+func (m *Me) xordec(data []byte) []byte {
+	batchsz := len(data) / 8
+	remain := len(data) % 8
+	this := uint64(0)
+	next := uint64(0)
+	if len(data) >= 8 {
+		next = binary.LittleEndian.Uint64(data[:8])
+	}
+	for i := 0; i < batchsz-1; i++ {
+		a := i * 8
+		b := (i + 1) * 8
+		this = next
+		next = binary.LittleEndian.Uint64(data[a+8 : b+8])
+		binary.LittleEndian.PutUint64(data[a:b], this^next)
+	}
 	if remain > 0 {
 		var buf [8]byte
-		copy(buf[:], data[remain:])
-		sum ^= binary.LittleEndian.Uint64(buf[:])
-		binary.LittleEndian.PutUint64(buf[:], sum)
-		copy(data[remain:], buf[:])
+		a := (batchsz - 1) * 8
+		b := batchsz * 8
+		copy(buf[:], data[b:])
+		this = next
+		next = binary.LittleEndian.Uint64(buf[:]) | (m.mask & (uint64(0xffffffff_ffffffff) << (uint64(remain) * 8)))
+		if batchsz > 0 {
+			binary.LittleEndian.PutUint64(data[a:b], this^next)
+		}
+		binary.LittleEndian.PutUint64(buf[:], next^m.mask)
+		copy(data[b:], buf[:])
+	} else {
+		binary.LittleEndian.PutUint64(data[len(data)-8:], next^m.mask)
 	}
 	return data
 }

gold/link/crypto_test.go

@@ -3,6 +3,7 @@ package link
 import (
 	"bytes"
 	"crypto/rand"
+	"io"
 	"testing"
 )
 
@@ -10,15 +11,20 @@ func TestXOR(t *testing.T) {
 	m := Me{
 		mask: 0x12345678_90abcdef,
 	}
-	buf := make([]byte, 65535)
-	for i := 1; i < 65536; i++ {
+	buf := make([]byte, 4096)
+	buf2 := make([]byte, 4096)
+	for i := 1; i < 4096; i++ {
 		data := buf[:i]
-		_, err := rand.Read(data)
+		orgdata := buf2[:i]
+		r1 := bytes.NewBuffer(data[:0])
+		r2 := bytes.NewBuffer(orgdata[:0])
+		w := io.MultiWriter(r1, r2)
+		_, err := io.CopyN(w, rand.Reader, int64(i))
 		if err != nil {
 			t.Fatal(err)
 		}
-		if !bytes.Equal(m.xor(m.xor(data)), data) {
-			t.Fatal("unexpected xor at ", i)
+		if !bytes.Equal(m.xordec(m.xorenc(r1.Bytes())), r2.Bytes()) {
+			t.Fatal("unexpected xor at", i)
 		}
 	}
 }

gold/link/me.go

@@ -2,6 +2,7 @@ package link
 
 import (
 	"encoding/binary"
+	"encoding/hex"
 	"io"
 	"net"
 	"strconv"
@@ -99,6 +100,9 @@ func NewMe(cfg *MyConfig) (m Me) {
 	m.dstport = cfg.DstPort
 	m.mtu = cfg.MTU & 0xfff8
 	m.mask = cfg.Mask
+	var buf [8]byte
+	binary.BigEndian.PutUint64(buf[:], m.mask)
+	logrus.Infoln("[me] xor mask", hex.EncodeToString(buf[:]))
 	if m.writer == nil {
 		m.writer = helper.SelectWriter()
 	}

gold/link/recv.go

@@ -18,14 +18,14 @@ func (m *Me) wait(data []byte) *head.Packet {
 	if len(data) < 60 { // not a valid packet
 		return nil
 	}
-	bound := 256
+	bound := 64
 	endl := "..."
 	if len(data) < bound {
 		bound = len(data)
 		endl = "."
 	}
 	logrus.Debugln("[recv] data bytes", hex.EncodeToString(data[:bound]), endl)
-	data = m.xor(data)
+	data = m.xordec(data)
 	logrus.Debugln("[recv] data xored", hex.EncodeToString(data[:bound]), endl)
 	flags := binary.LittleEndian.Uint16(data[10:12])
 	if flags&0x8000 == 0x8000 { // not a valid packet

gold/link/send.go

@@ -99,7 +99,7 @@ func (l *Link) write(p *head.Packet, teatype uint8, additional, mtu uint16, data
 		if peerep == nil {
 			return 0, errors.New("[send] nil endpoint of " + p.Dst.String())
 		}
-		bound := 256
+		bound := 64
 		endl := "..."
 		if len(d) < bound {
 			bound = len(d)
@@ -107,9 +107,9 @@ func (l *Link) write(p *head.Packet, teatype uint8, additional, mtu uint16, data
 		}
 		logrus.Debugln("[send] write", len(d), "bytes data from ep", l.me.myep.LocalAddr(), "to", peerep, "offset:", fmt.Sprintf("%04x", offset))
 		logrus.Debugln("[send] data bytes", hex.EncodeToString(d[:bound]), endl)
-		d = l.me.xor(d)
-		n, err = l.me.myep.WriteToUDP(d, peerep)
+		d = l.me.xorenc(d)
 		logrus.Debugln("[send] data xored", hex.EncodeToString(d[:bound]), endl)
+		n, err = l.me.myep.WriteToUDP(d, peerep)
 		cl()
 	}
 	return