tcp 粘包处理 client

client.go

// 参考链接https://feixiao.github.io/2016/05/08/bufio/
package main

import (
	"bufio"
	"bytes"
	"encoding/binary"
	"flag"
	"fmt"
	"io"
	"net"
	"os"
	"strconv"
)

var host = flag.String("host", "localhost", "The hostname or IP to connect to; defaults to \"localhost\".")
var port = flag.Int("port", 8000, "The port to connect to; defaults to 8000.")

// 自定义协议的组包和拆包
type Package struct {
	Version [2]int8
	Datalen int64
	Data    []byte
}

func (p *Package) String() string {
	return fmt.Sprintf("Version:%d DataLen:%d Data:%s",
		p.Version, p.Datalen, p.Data)
}

func (p *Package) Pack(w io.Writer) {
	binary.Write(w, binary.BigEndian, p.Version)
	binary.Write(w, binary.BigEndian, p.Datalen)
	binary.Write(w, binary.BigEndian, p.Data)
}

func (p *Package) Unpack(r io.Reader) {
	binary.Read(r, binary.BigEndian, &p.Version)
	binary.Read(r, binary.BigEndian, &p.Datalen)
	if p.Datalen > 0 {
		p.Data = make([]byte, p.Datalen)
	}
	binary.Read(r, binary.BigEndian, &p.Data)
}

func main() {
	flag.Parse()

	dest := *host + ":" + strconv.Itoa(*port)
	fmt.Printf("Connecting to %s...\n", dest)

	conn, err := net.Dial("tcp", dest)

	if err != nil {
		if _, t := err.(*net.OpError); t {
			fmt.Println("Some problem connecting.")
		} else {
			fmt.Println("Unknown error: " + err.Error())
		}
		os.Exit(1)
	}

	readConnection(conn)
}

func readConnection(conn net.Conn) {

	scanner := bufio.NewScanner(conn)
	// 数据的分离规则，根据协议自定义

	//设置分离函数
	split := func(data []byte, atEOF bool) (advance int, token []byte, err error) {
		if !atEOF && bytes.Equal(data[:2], []byte("V1")) {
			if len(data) > 10 {
				var dataLen int64
				binary.Read(bytes.NewReader(data[2:10]), binary.BigEndian, &dataLen)
				if int(dataLen)+10 <= len(data) {
					token = data[int64(10) : int64(10)+int64(dataLen)]
					return int(dataLen) + 10, token, nil
				}
			}
		}
		return
	}

	scanner.Split(split)

	for {

		for scanner.Scan() {
			//fmt.Println(string(scanner.Text())
			fmt.Println(scanner.Bytes())
		}

		if err := scanner.Err(); err != nil {
			fmt.Printf("Invalid input: %s", err)
		}

	}

}