go语言 TCP粘包问题处理

package main

import (
	"bytes"
	"encoding/binary"
	"encoding/json"
	"fmt"
	"log"
	"net"
)

const BUF_SIZE = 1024
const HEAD_SIZE = 50

type Header struct {
	DataLength int    `json:"data_length"`
	Fill       string `json:"fill"`
}

func PackMsgHeader(header *Header) {
	marshaled, _ := json.Marshal(header)
	fillUpSize := HEAD_SIZE - len(marshaled)
	fillStr := ""
	for i := 0; i < fillUpSize; i++ {
		fillStr += "0"
	}
	header.Fill = fillStr
}
func doConn(conn net.Conn) {
	var (
		buffer    = bytes.NewBuffer(make([]byte, 0, BUF_SIZE)) //buffer用来缓存读取到的数据
		readBytes = make([]byte, BUF_SIZE)                     //readBytes用来接收每次读取的数据，每次读取完成之后将readBytes添加到buffer中
		isHead    = true                                       //用来标识当前的状态：正在处理size部分还是body部分
		bodyLen   = 0                                          //表示body的长度
	)

	for {
		//首先读取数据
		readByteNum, err := conn.Read(readBytes)
		if err != nil {
			log.Fatal(err)
			return
		}
		buffer.Write(readBytes[0:readByteNum]) //将读取到的数据放到buffer中

		// 然后处理数据
		for {
			if isHead {
				if buffer.Len() >= HEAD_SIZE {
					isHead = false
					head := make([]byte, HEAD_SIZE)
					_, err = buffer.Read(head)
					if err != nil {
						log.Fatal(err)
						return
					}
					header := &Header{}
					json.Unmarshal(head, &header)
					bodyLen = header.DataLength
				} else {
					break
				}
			}

			if !isHead {
				if buffer.Len() >= bodyLen {
					body := make([]byte, bodyLen)
					_, err = buffer.Read(body[:bodyLen])
					if err != nil {
						log.Fatal(err)
						return
					}
					fmt.Println("received body: " + string(body[:bodyLen]))
					isHead = true
				} else {
					break
				}
			}
		}
	}
}

func Test_tcp_serve1() {
	listener, err := net.Listen("tcp", "127.0.0.1:1234")
	if err != nil {
		log.Fatal(err)
		return
	}
	log.Println("start listening on 1234")
	for {
		conn, err := listener.Accept()
		if err != nil {
			log.Fatal(err)
			return
		}
		go doConn(conn)
	}
}

func SendStringwithTcp(arg string) error {
	conn, err := net.Dial("tcp", ":1234")
	if err != nil {
		log.Fatal(err)
		return err
	}

	head := make([]byte, HEAD_SIZE)
	content := []byte(arg)
	headSize := len(content)
	binary.BigEndian.PutUint16(head, uint16(headSize))

	//先写入head部分，再写入body部分
	_, err = conn.Write(head)
	if err != nil {
		log.Fatal(err)
		return err
	}
	_, err = conn.Write(content)
	if err != nil {
		log.Fatal(err)
		return err
	}
	return nil
}

func Test_tcp_cli1() {
	conn, _ := net.Dial("tcp", "127.0.0.1:1234")
	msg := "YFR718sssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssss"
	for i := 0; i < 200; i++ {

		content := []byte(msg)
		contentSize := len(content)
		header := &Header{
			DataLength: contentSize,
			Fill:       "",
		}
		PackMsgHeader(header)
		headerMarshaled, _ := json.Marshal(header)

		//先写入head部分，再写入body部分
		conn.Write(headerMarshaled)
		conn.Write(content)

	}

}


func main() {

	go func() {
		Test_tcp_serve1()
	}()

	go func() {
		Test_tcp_cli1()
	}()
	time.Sleep(1 * time.Hour)

}