Chore: split component to transport

transport/ssr/protocol/protocol.go

@@ -0,0 +1,76 @@
+package protocol
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"math/rand"
+	"net"
+)
+
+var (
+	errAuthSHA1V4CRC32Error   = errors.New("auth_sha1_v4 decode data wrong crc32")
+	errAuthSHA1V4LengthError  = errors.New("auth_sha1_v4 decode data wrong length")
+	errAuthSHA1V4Adler32Error = errors.New("auth_sha1_v4 decode data wrong adler32")
+	errAuthAES128MACError     = errors.New("auth_aes128 decode data wrong mac")
+	errAuthAES128LengthError  = errors.New("auth_aes128 decode data wrong length")
+	errAuthAES128ChksumError  = errors.New("auth_aes128 decode data wrong checksum")
+	errAuthChainLengthError   = errors.New("auth_chain decode data wrong length")
+	errAuthChainChksumError   = errors.New("auth_chain decode data wrong checksum")
+)
+
+type Protocol interface {
+	StreamConn(net.Conn, []byte) net.Conn
+	PacketConn(net.PacketConn) net.PacketConn
+	Decode(dst, src *bytes.Buffer) error
+	Encode(buf *bytes.Buffer, b []byte) error
+	DecodePacket([]byte) ([]byte, error)
+	EncodePacket(buf *bytes.Buffer, b []byte) error
+}
+
+type protocolCreator func(b *Base) Protocol
+
+var protocolList = make(map[string]struct {
+	overhead int
+	new      protocolCreator
+})
+
+func register(name string, c protocolCreator, o int) {
+	protocolList[name] = struct {
+		overhead int
+		new      protocolCreator
+	}{overhead: o, new: c}
+}
+
+func PickProtocol(name string, b *Base) (Protocol, error) {
+	if choice, ok := protocolList[name]; ok {
+		b.Overhead += choice.overhead
+		return choice.new(b), nil
+	}
+	return nil, fmt.Errorf("protocol %s not supported", name)
+}
+
+func getHeadSize(b []byte, defaultValue int) int {
+	if len(b) < 2 {
+		return defaultValue
+	}
+	headType := b[0] & 7
+	switch headType {
+	case 1:
+		return 7
+	case 4:
+		return 19
+	case 3:
+		return 4 + int(b[1])
+	}
+	return defaultValue
+}
+
+func getDataLength(b []byte) int {
+	bLength := len(b)
+	dataLength := getHeadSize(b, 30) + rand.Intn(32)
+	if bLength < dataLength {
+		return bLength
+	}
+	return dataLength
+}