feat(proto): 自 go-hua 迁入长度前缀封包协议编解码

- 8 字节头(4 字节 ID/校验 + 4 字节长度, 小端序) + CRC32 校验版本 - 附测试、examples/proto 例程与包 README(含 Decode reader 复用告诫)
2026-09-20 12:25:35 +08:00
parent 80eb62cb08
commit b478482f21
4 changed files with 392 additions and 0 deletions
@@ -0,0 +1,213 @@
+// Package proto 提供长度前缀封包协议的编解码（8 字节头：4 字节 ID/校验 + 4 字节长度，小端序），支持 CRC32 校验版本。
+package proto
+
+import (
+	"bufio"
+	"bytes"
+	"encoding/binary"
+	"errors"
+	"hash/crc32"
+)
+
+// PakHeadLen 消息头长度：普通版为 ID 4 字节 + 长度 4 字节；CRC32 版为校验值 4 字节 + 长度 4 字节
+const (
+	PakHeadLen int32 = 8
+)
+
+// Encode 编码
+func Encode(buf []byte) ([]byte, error) {
+	// 读取消息的长度，转换成int32类型（占4个字节）
+	var id int32 = 5
+	var length = int32(len(buf))
+	var pkg = new(bytes.Buffer)
+	// 写入消息头
+	err := binary.Write(pkg, binary.LittleEndian, id)
+	if err != nil {
+		return nil, err
+	}
+	err = binary.Write(pkg, binary.LittleEndian, length)
+	if err != nil {
+		return nil, err
+	}
+	// 写入消息实体
+	err = binary.Write(pkg, binary.LittleEndian, []byte(buf))
+	if err != nil {
+		return nil, err
+	}
+	return pkg.Bytes(), nil
+}
+
+// Decode 解码
+func Decode(reader *bufio.Reader) ([]byte, error) {
+	// 读取头部
+	lengthByte, err := reader.Peek(int(PakHeadLen)) // 读取前4个字节的数据
+	if err != nil {
+		return nil, err
+	}
+	lengthBuff := bytes.NewBuffer(lengthByte)
+	var id int32 = 0
+	var length int32 = 0
+
+	err = binary.Read(lengthBuff, binary.LittleEndian, &id)
+	if err != nil {
+		return nil, err
+	}
+	err = binary.Read(lengthBuff, binary.LittleEndian, &length)
+	if err != nil {
+		return nil, err
+	}
+
+	if length <= 0 {
+		return nil, errors.New("decode length cannot be less than 0")
+	}
+
+	if length > 0x1000000 {
+		return nil, errors.New("decode length cannot be greater than 0x1000000")
+	}
+
+	var data []byte
+
+	// 剩余读长长度
+	unread := int(PakHeadLen + length)
+	readLen := 0
+	for {
+		if unread > 0x10000 {
+			readLen = 0x10000
+		} else {
+			readLen = unread
+		}
+
+		_, err = reader.Peek(readLen) // 先窥探数据
+		if err != nil {
+			return nil, err
+		}
+
+		// Buffered返回缓冲中现有的可读取的字节数。
+		if reader.Buffered() < readLen {
+			return nil, err
+		}
+
+		// 读取
+		buf := make([]byte, readLen)
+		_, err = reader.Read(buf)
+		if err != nil {
+			return nil, err
+		}
+		data = append(data, buf...)
+
+		unread -= readLen
+		//fmt.Println("readLen", readLen)
+		if unread <= 0 {
+			break
+		}
+
+	}
+
+	if len(data) < int(PakHeadLen) {
+		return nil, nil
+	}
+
+	return data[PakHeadLen:], nil
+}
+
+// EncodeCrc32 编码 Crc32校验
+func EncodeCrc32(buf []byte) ([]byte, error) {
+	// 读取消息的长度，转换成int32类型（占4个字节）
+	ieee := crc32.NewIEEE()
+	ieee.Write(buf)
+	var crc = ieee.Sum32()
+	var length = int32(len(buf))
+	var pkg = new(bytes.Buffer)
+	// 写入消息头
+	err := binary.Write(pkg, binary.LittleEndian, crc)
+	if err != nil {
+		return nil, err
+	}
+	err = binary.Write(pkg, binary.LittleEndian, length)
+	if err != nil {
+		return nil, err
+	}
+	// 写入消息实体
+	err = binary.Write(pkg, binary.LittleEndian, []byte(buf))
+	if err != nil {
+		return nil, err
+	}
+	return pkg.Bytes(), nil
+}
+
+// DecodeCrc32 解码 Crc32校验
+func DecodeCrc32(reader *bufio.Reader) ([]byte, error) {
+	// 读取头部
+	lengthByte, err := reader.Peek(int(PakHeadLen)) // 读取前4个字节的数据
+	if err != nil {
+		return nil, err
+	}
+	lengthBuff := bytes.NewBuffer(lengthByte)
+	var crc uint32 = 0
+	var length int32 = 0
+
+	err = binary.Read(lengthBuff, binary.LittleEndian, &crc)
+	if err != nil {
+		return nil, err
+	}
+	err = binary.Read(lengthBuff, binary.LittleEndian, &length)
+	if err != nil {
+		return nil, err
+	}
+
+	if length <= 0 {
+		return nil, errors.New("decode length cannot be less than 0")
+	}
+
+	if length > 0x1000000 {
+		return nil, errors.New("decode length cannot be greater than 0x1000000")
+	}
+
+	var data []byte
+
+	// 剩余读长长度
+	unread := int(PakHeadLen + length)
+	readLen := 0
+	for {
+		if unread > 0x1000 {
+			readLen = 0x1000
+		} else {
+			readLen = unread
+		}
+
+		_, err = reader.Peek(readLen) // 先窥探数据
+		if err != nil {
+			return nil, err
+		}
+
+		// Buffered返回缓冲中现有的可读取的字节数。
+		if reader.Buffered() < readLen {
+			return nil, err
+		}
+
+		// 读取
+		buf := make([]byte, readLen)
+		_, err = reader.Read(buf)
+		if err != nil {
+			return nil, err
+		}
+		data = append(data, buf...)
+
+		unread -= readLen
+		//fmt.Println("readLen", readLen)
+		if unread <= 0 {
+			break
+		}
+
+	}
+
+	if len(data) < int(PakHeadLen) {
+		return nil, nil
+	}
+	ieee := crc32.NewIEEE()
+	ieee.Write(data[PakHeadLen:])
+	if crc != ieee.Sum32() {
+		return nil, errors.New("crc check error")
+	}
+	return data[PakHeadLen:], nil
+}