refactor: Move vision implementation to a new package

transport/vless/vision/padding.go

@@ -0,0 +1,81 @@
+package vision
+
+import (
+	"bytes"
+	"encoding/binary"
+
+	"github.com/Dreamacro/clash/common/buf"
+	"github.com/Dreamacro/clash/log"
+
+	"github.com/gofrs/uuid/v5"
+	"github.com/zhangyunhao116/fastrand"
+)
+
+const (
+	PaddingHeaderLen = uuid.Size + 1 + 2 + 2 // =21
+
+	commandPaddingContinue byte = 0x00
+	commandPaddingEnd      byte = 0x01
+	commandPaddingDirect   byte = 0x02
+)
+
+func WriteWithPadding(buffer *buf.Buffer, p []byte, command byte, userUUID *uuid.UUID, paddingTLS bool) {
+	contentLen := int32(len(p))
+	var paddingLen int32
+	if contentLen < 900 {
+		if paddingTLS {
+			//log.Debugln("long padding")
+			paddingLen = fastrand.Int31n(500) + 900 - contentLen
+		} else {
+			paddingLen = fastrand.Int31n(256)
+		}
+	}
+	if userUUID != nil {
+		buffer.Write(userUUID.Bytes())
+	}
+
+	buffer.WriteByte(command)
+	binary.BigEndian.PutUint16(buffer.Extend(2), uint16(contentLen))
+	binary.BigEndian.PutUint16(buffer.Extend(2), uint16(paddingLen))
+	buffer.Write(p)
+
+	buffer.Extend(int(paddingLen))
+	log.Debugln("XTLS Vision write padding1: command=%v, payloadLen=%v, paddingLen=%v", command, contentLen, paddingLen)
+}
+
+func ApplyPadding(buffer *buf.Buffer, command byte, userUUID *uuid.UUID, paddingTLS bool) {
+	contentLen := int32(buffer.Len())
+	var paddingLen int32
+	if contentLen < 900 {
+		if paddingTLS {
+			//log.Debugln("long padding")
+			paddingLen = fastrand.Int31n(500) + 900 - contentLen
+		} else {
+			paddingLen = fastrand.Int31n(256)
+		}
+	}
+
+	binary.BigEndian.PutUint16(buffer.ExtendHeader(2), uint16(paddingLen))
+	binary.BigEndian.PutUint16(buffer.ExtendHeader(2), uint16(contentLen))
+	buffer.ExtendHeader(1)[0] = command
+	if userUUID != nil {
+		copy(buffer.ExtendHeader(uuid.Size), userUUID.Bytes())
+	}
+
+	buffer.Extend(int(paddingLen))
+	log.Debugln("XTLS Vision write padding2: command=%d, payloadLen=%d, paddingLen=%d", command, contentLen, paddingLen)
+}
+
+func ReshapeBuffer(buffer *buf.Buffer) *buf.Buffer {
+	if buffer.Len() <= buf.BufferSize-PaddingHeaderLen {
+		return nil
+	}
+	cutAt := bytes.LastIndex(buffer.Bytes(), tlsApplicationDataStart)
+	if cutAt == -1 {
+		cutAt = buf.BufferSize / 2
+	}
+	buffer2 := buf.New()
+	buffer2.Write(buffer.From(cutAt))
+	buffer.Truncate(cutAt)
+	return buffer2
+}