golang实现R6900路由器外网IP更新通知程序

程序一分钟执行一次，检测路由器外网IP地址变更则自动发送邮件，使用网易126 smtp协议发送邮件，邮箱地址及授权码请自行替换，getIp函数中的grep根据自己的网卡信息调试替换

R6900路由器的交叉编译语句：CGO_ENABLED=0 GOOS=linux GOARCH=arm GOARM=5 go build xxxx.go

package main

import (
    "fmt"
    "gopkg.in/gomail.v2"
    "io/ioutil"
    "log"
    "os/exec"
    "strconv"
    "time"
)

// 邮件主题
var subject = "路由器外网IP更新"

//定义收件人
var mailTo = []string{
    "****@qq.com",
    "****@163.com",
}

// ip地址
var ip string

func main() {
    ip := getIp()
    send(ip)
    ticker := time.NewTicker(time.Minute * 1)
    for range ticker.C {
        newIp := getIp()
        if newIp != ip {
           ip = newIp
           send(ip)
        }
    }
}

// 获取当前ip
func getIp() string {
    return execCmd("/usr/sbin/ip a | grep 'scope global ppp0' | awk '{print $2}'")
}

// 发送邮件
func send(ip string) {
    body := "新的外网IP为：" + ip
    log.Print(body)
    err := execSend(mailTo, subject, body)
    if err != nil {
        log.Print("mail send fail")
        log.Print(err)
        return
    }
    log.Print("mail send successfully")
}

// 执行发送
func execSend(mailTo []string, subject string, body string) error {
    mailConn := map[string]string{
        "user": "****@126.com",
        "pass": "********",
        "host": "smtp.126.com",
        "port": "25",
    }

    port, _ := strconv.Atoi(mailConn["port"])

    m := gomail.NewMessage()

    m.SetHeader("From", m.FormatAddress(mailConn["user"], "路由器R6900"))
    m.SetHeader("To", mailTo...)    //发送给多个用户
    m.SetHeader("Subject", subject) //设置邮件主题
    m.SetBody("text/html", body)    //设置邮件正文

    d := gomail.NewDialer(mailConn["host"], port, mailConn["user"], mailConn["pass"])

    err := d.DialAndSend(m)
    return err
}

// 执行shell命令
func execCmd(command string) string {
    cmd := exec.Command("/bin/sh", "-c", command)
    stdout, _ := cmd.StdoutPipe()
    if err := cmd.Start(); err != nil {
        fmt.Println("Execute failed when Start:" + err.Error())
        return ""
    }
    out_bytes, _ := ioutil.ReadAll(stdout)
    stdout.Close()

    if err := cmd.Wait(); err != nil {
        fmt.Println("Execute failed when Wait:" + err.Error())
        return ""
    }
    return string(out_bytes)
}