golang tcp 粘包拆包问题处理，完整demo

解决tcp粘包拆包问题，有多种处理方案，这里在数据包中添加数据包长度字段，按长度读取字节数据得到完整的数据包。定义的方法如下：

完整Demo下载：
https://github.com/itchin/bytes-packet

bytes-packet.go

package bpacket

import (
    //"fmt"
    "bytes"
    "encoding/binary"
)

var (
    // 完整的数据包
    packet = make([]byte, 0)
    // 缓存
    cache = make([]byte, 0)
)

const (
    // 每个数据包前4个字节保存一个整形，该整形记录数据包的字节长度
    HEADER_LEN = 4
)

// 打包
func Packet(buf []byte) []byte {
    return append(intToBytes(len(buf)), buf...)
}

// 解包
func Unpack(buf []byte) ([]byte) {
    buf = append(cache, buf...)
    length := len(buf)

    messageLength := bytesToInt(buf[:HEADER_LEN])
    // 当前数据包的总长度
    total := HEADER_LEN + messageLength
    if length < total {
        cache = buf
        return []byte{}
    } else if (length == total) {
        cache = []byte{}
        return buf[HEADER_LEN:]
    } else {
        cache = buf[total:]
        return buf[HEADER_LEN:total]
    }
}

//整形转换成字节
func intToBytes(n int) []byte {
    x := int32(n)

    bytesBuffer := bytes.NewBuffer([]byte{})
    binary.Write(bytesBuffer, binary.BigEndian, x)
    return bytesBuffer.Bytes()
}

//字节转换成整形
func bytesToInt(b []byte) int {
    bytesBuffer := bytes.NewBuffer(b)

    var x int32
    binary.Read(bytesBuffer, binary.BigEndian, &x)

    return int(x)
}

Demo：

server.go

package main

import (
    "fmt"
    "io"
    "net"
    "github.com/itchin/bytes-packet"
)

func main() {
    server, err := net.Listen("tcp", ":9000")
    if err != nil {
        panic(err)
    }
    defer server.Close()

    for {
        conn, err := server.Accept()
        if err != nil {
            continue
        }
        defer conn.Close()
        go run(conn)
    }
}

func run(conn net.Conn) {
    // 每次读取的字节流
    buf := make([]byte, 1)

    for {
        n, err := conn.Read(buf)

        if err != nil || err == io.EOF {
            conn.Close()
            break
        }

        packet := bpacket.Unpack(buf[:n])
        if len(packet) > 0 {
            fmt.Println(string(packet))
        }
    }
}

client.go

package main

import (
    "fmt"
    "github.com/itchin/bytes-packet"
    "net"
    "time"
)

func main() {
    conn, err := net.Dial("tcp", "127.0.0.1:9000")
    if err != nil {
        fmt.Printf("connect failed, err : %v\n", err.Error())
        return
    }
    defer conn.Close()

    msg := "hello world"

    conn.Write(bpacket.Packet([]byte(msg)))
    time.Sleep(time.Second / 10)
}

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