完成TPKT、X224、FastPath协议基本封装和测试

protocol/x224.go

@@ -0,0 +1,139 @@
+package protocol
+
+import (
+	"bytes"
+	"encoding/binary"
+	"errors"
+	"io"
+)
+
+/* 协议常量 */
+
+// X224消息头部长度
+const (
+	X224_HEADER_LENGTH = 0x07
+)
+
+// X224消息类型字段标识
+const (
+	X224_CONNECTION_REQUEST byte = 0xE0
+	X224_CONNECTION_CONFIRM byte = 0xD0
+	X224_DISCONNECT_REQUEST byte = 0x80
+	X224_DATA               byte = 0xF0
+	X224_ERROR              byte = 0x70
+)
+
+// X224 协议封装
+type X224 struct {
+	transport   *TPKT
+	reqProtocol uint32
+	selProtocol uint32
+}
+
+type X224PDU struct {
+	Len     uint8
+	Type    byte
+	DstRef  uint16 // 大端序
+	SrcRef  uint16 // 大端序
+	ClsOpt  uint8
+	Payload []byte
+}
+
+func NewX224(conn io.ReadWriter) *X224 {
+	return &X224{
+		transport: NewTPKT(conn),
+	}
+}
+
+// 从字节流中解析PDU头部
+func (x *X224) parsePDUHeader(reader *bytes.Reader, pdu *X224PDU) error {
+	var err error
+
+	// 读取Len字段
+	err = binary.Read(reader, binary.BigEndian, &pdu.Len)
+	if err != nil {
+		return errors.New("[X224] failed to read pdu length: " + err.Error())
+	}
+
+	// 读取Type字段
+	err = binary.Read(reader, binary.BigEndian, &pdu.Type)
+	if err != nil {
+		return errors.New("[X224] failed to read pdu type: " + err.Error())
+	}
+
+	// 读取DstRef（大端序）
+	err = binary.Read(reader, binary.BigEndian, &pdu.DstRef)
+	if err != nil {
+		return errors.New("[X224] failed to read pdu dstref: " + err.Error())
+	}
+
+	// 读取SrcRef（大端序）
+	err = binary.Read(reader, binary.BigEndian, &pdu.SrcRef)
+	if err != nil {
+		return errors.New("[X224] failed to read pdu srcref: " + err.Error())
+	}
+
+	// 读取ClsOpt
+	err = binary.Read(reader, binary.BigEndian, &pdu.ClsOpt)
+	if err != nil {
+		return errors.New("[X224] failed to read pdu clsopt: " + err.Error())
+	}
+
+	return nil
+}
+
+// 序列化X224PDU
+func (x *X224) serializeX224PDU(pdu *X224PDU) []byte {
+	buff := bytes.NewBuffer(nil)
+	_ = binary.Write(buff, binary.BigEndian, pdu.Len)
+	_ = binary.Write(buff, binary.BigEndian, pdu.Type)
+	_ = binary.Write(buff, binary.BigEndian, pdu.DstRef)
+	_ = binary.Write(buff, binary.BigEndian, pdu.SrcRef)
+	_ = binary.Write(buff, binary.BigEndian, pdu.ClsOpt)
+
+	buff.Write(pdu.Payload)
+	return buff.Bytes()
+}
+
+// 封包
+func (x *X224) Write(payload []byte) error {
+	pdu := &X224PDU{
+		Len:     uint8(X224_HEADER_LENGTH + len(payload)), // 头部长度 + 载荷字段
+		Type:    X224_DATA,
+		DstRef:  0xf0,
+		SrcRef:  0xf1,
+		ClsOpt:  0x0,
+		Payload: payload,
+	}
+
+	payloadBytes := x.serializeX224PDU(pdu)
+	err := x.transport.Write(payloadBytes)
+	if err != nil {
+		return errors.New("[X224] failed to write: " + err.Error())
+	}
+
+	return nil
+}
+
+// 解包
+func (x *X224) Read() ([]byte, error) {
+	packet, err := x.transport.Read()
+	if err != nil {
+		return nil, errors.New("[X224] failed to read: " + err.Error())
+	}
+
+	pdu := &X224PDU{}
+	reader := bytes.NewReader(packet)
+
+	err = x.parsePDUHeader(reader, pdu)
+	if err != nil {
+		return nil, errors.New("[X224] failed to parse pdu header: " + err.Error())
+	}
+
+	payload, err := io.ReadAll(reader)
+	if err != nil {
+		return nil, errors.New("[X224] failed to read payload: " + err.Error())
+	}
+
+	return payload, nil
+}