Use SHA3-256 instead of SHA2-256; Support XTLS Vision for random appearance

https://github.com/XTLS/Xray-core/pull/4952#issuecomment-3197163816

proxy/vless/encryption/xor.go

@@ -15,6 +15,14 @@ type XorConn struct {
 	peerCtr  cipher.Stream
 	isHeader bool
 	skipNext bool
+
+	out_after0 bool
+	out_header []byte
+	out_skip   int
+
+	in_after0 bool
+	in_header []byte
+	in_skip   int
 }
 
 func NewXorConn(conn net.Conn, key []byte) *XorConn {
@@ -26,29 +34,56 @@ func (c *XorConn) Write(b []byte) (int, error) { // whole one/two records
 	if len(b) == 0 {
 		return 0, nil
 	}
-	var iv []byte
-	if c.ctr == nil {
-		block, _ := aes.NewCipher(c.key)
-		iv = make([]byte, 16)
-		rand.Read(iv)
-		c.ctr = cipher.NewCTR(block, iv)
+	if !c.out_after0 {
+		var iv []byte
+		if c.ctr == nil {
+			block, _ := aes.NewCipher(c.key)
+			iv = make([]byte, 16)
+			rand.Read(iv)
+			c.ctr = cipher.NewCTR(block, iv)
+		}
+		t, l, _ := DecodeHeader(b)
+		if t == 23 { // single 23
+			l = 5
+		} else { // 1/0 + 23, or noises only
+			l += 10
+			if t == 0 {
+				c.out_after0 = true
+			}
+		}
+		c.ctr.XORKeyStream(b[:l], b[:l]) // caller MUST discard b
+		if iv != nil {
+			b = append(iv, b...)
+		}
+		if _, err := c.Conn.Write(b); err != nil {
+			return 0, err
+		}
+		if iv != nil {
+			b = b[16:] // for len(b)
+		}
+		return len(b), nil
 	}
-	t, l, _ := DecodeHeader(b)
-	if t == 23 { // single 23
-		l = 5
-	} else { // 1/0 + 23, or noises only
-		l += 10
-	}
-	c.ctr.XORKeyStream(b[:l], b[:l]) // caller MUST discard b
-	if iv != nil {
-		b = append(iv, b...)
+	for p := b; ; { // for XTLS
+		if len(p) <= c.out_skip {
+			c.out_skip -= len(p)
+			break
+		}
+		p = p[c.out_skip:]
+		c.out_skip = 0
+		need := 5 - len(c.out_header)
+		if len(p) < need {
+			c.out_header = append(c.out_header, p...)
+			c.ctr.XORKeyStream(p, p)
+			break
+		}
+		_, c.out_skip, _ = DecodeHeader(append(c.out_header, p[:need]...))
+		c.out_header = make([]byte, 0, 5) // DO NOT CHANGE
+		c.ctr.XORKeyStream(p[:need], p[:need])
+		p = p[need:]
 	}
 	if _, err := c.Conn.Write(b); err != nil {
 		return 0, err
 	}
-	if iv != nil {
-		b = b[16:] // for len(b)
-	}
 	return len(b), nil
 }
 
@@ -56,31 +91,56 @@ func (c *XorConn) Read(b []byte) (int, error) { // 5-bytes, data, 5-bytes...
 	if len(b) == 0 {
 		return 0, nil
 	}
-	if c.peerCtr == nil {
-		peerIv := make([]byte, 16)
-		if _, err := io.ReadFull(c.Conn, peerIv); err != nil {
+	if !c.in_after0 || !c.isHeader {
+		if c.peerCtr == nil {
+			peerIv := make([]byte, 16)
+			if _, err := io.ReadFull(c.Conn, peerIv); err != nil {
+				return 0, err
+			}
+			block, _ := aes.NewCipher(c.key)
+			c.peerCtr = cipher.NewCTR(block, peerIv)
+			c.isHeader = true
+		}
+		if _, err := io.ReadFull(c.Conn, b); err != nil {
 			return 0, err
 		}
-		block, _ := aes.NewCipher(c.key)
-		c.peerCtr = cipher.NewCTR(block, peerIv)
-		c.isHeader = true
-	}
-	if _, err := io.ReadFull(c.Conn, b); err != nil {
-		return 0, err
-	}
-	if c.skipNext {
-		c.skipNext = false
+		if c.skipNext {
+			c.skipNext = false
+			return len(b), nil
+		}
+		c.peerCtr.XORKeyStream(b, b)
+		if c.isHeader { // always 5-bytes
+			if t, _, _ := DecodeHeader(b); t == 23 {
+				c.skipNext = true
+			} else {
+				c.isHeader = false
+				if t == 0 {
+					c.in_after0 = true
+				}
+			}
+		} else {
+			c.isHeader = true
+		}
 		return len(b), nil
 	}
-	c.peerCtr.XORKeyStream(b, b)
-	if c.isHeader { // always 5-bytes
-		if t, _, _ := DecodeHeader(b); t == 23 {
-			c.skipNext = true
-		} else {
-			c.isHeader = false
+	n, err := c.Conn.Read(b)
+	for p := b[:n]; ; { // for XTLS
+		if len(p) <= c.in_skip {
+			c.in_skip -= len(p)
+			break
 		}
-	} else {
-		c.isHeader = true
+		p = p[c.in_skip:]
+		c.in_skip = 0
+		need := 5 - len(c.in_header)
+		if len(p) < need {
+			c.peerCtr.XORKeyStream(p, p)
+			c.in_header = append(c.in_header, p...)
+			break
+		}
+		c.peerCtr.XORKeyStream(p[:need], p[:need])
+		_, c.in_skip, _ = DecodeHeader(append(c.in_header, p[:need]...))
+		c.in_header = make([]byte, 0, 5) // DO NOT CHANGE
+		p = p[need:]
 	}
-	return len(b), nil
+	return n, err
 }