【golang】发送自定义数量的UDP报文

package main

import (
	"net"
	"fmt"
	"flag"
	"context"
	"time"
)

const (
	IP = "192.168.0.245"
	PORT = "514"
)

var (
	number int
	count int
	timer bool
	mesg = "<10>Apr 29 17:59:08 localhost t_syslog[29121]: This is a syslog test message generated by program './t_syslog'"
)

func SendMesg(number, cnt int, timer bool) (err error) {
	Addr := IP + ":" + PORT
	conn, err := net.Dial("udp", Addr)
	if err != nil {
		fmt.Println("Dial() err:", err)
		return err
	}
	defer conn.Close()

	ch := make(chan bool)
	ctx, cancel := context.WithCancel(context.Background())

	var sendNum int = 0
	go func() {
		select {
		case <-time.After(1 * time.Second):
			fmt.Printf("In a second, %d messages send\n", sendNum)
		case <-ctx.Done():
			fmt.Printf("Less than a second, %d messages send!\n", sendNum)
		}
		ch <- true
	}()

	sendData := []byte(mesg)
	for i := 0; i < number; i++ {
		_, err = conn.Write(sendData)
		if err != nil {
			fmt.Println("Write() err:", err)
			break
		}
		sendNum++
	}
	if !timer {
		cancel()
	}
	<-ch 
	return err
}

func main() {
	flag.IntVar(&number, "n", 100, "number of message to send")
	flag.IntVar(&count, "c", 1, "frequency")
	flag.BoolVar(&timer, "t", false, "send in a second")
	flag.Parse()

	t1 := time.Now()
	for i := 0; i < count; i++ {
		err := SendMesg(number, i, timer)
		if err != nil {
			break
		}
	}
	fmt.Println("Total sending time:", time.Since(t1))
}