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 }