main.go

package main

import (
	"crypto/tls"
	"encoding/json"
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
	"os"
	"strings"
	"time"
)

type Auth struct {
	Username string `json:"username"`
	Password string `json:"password"`
}

var client *http.Client

func readConf() (*Auth, error) {
	b, err := ioutil.ReadFile("config.json")
	if err != nil {
		log.Println(err)
		return nil, err
	}

	auth := new(Auth)
	err = json.Unmarshal(b, auth)
	return auth, err
}

func connect(auth *Auth) error {
	postForm := fmt.Sprintf(
		"buttonClicked=4&redirect_url=&err_flag=0&username=%s&password=%s",
		auth.Username,
		auth.Password,
	)

	postForm = strings.Replace(postForm, " ", "%20", -1)

	reader := strings.NewReader(postForm)

	req, err := http.NewRequest("POST", "https://2.2.2.2/login.html", reader)
	if err != nil {
		return err
	}

	req.Header.Set("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8")
	req.Header.Set("Accept-Encoding", "gzip, deflate")
	req.Header.Set("Accept-Language", "zh-CN,zh;q=0.8,en-US;q=0.5,en;q=0.3")
	req.Header.Set("Connection", "keep-alive")
	req.Header.Set("Host", "2.2.2.2")
	req.Header.Set("User-Agent", "Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:41.0) Gecko/20100101 Firefox/41.0")
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")

	resp, err := client.Do(req)
	if err != nil {
		return err
	}

	data, _ := ioutil.ReadAll(resp.Body)
	idx := strings.Index(string(data), "Login Successful")
	if idx < 0 {
		return fmt.Errorf("login failed")
	}

	return nil
}

func Check() bool {
	req, err := http.NewRequest("GET", "https://baidu.com", nil)
	if err != nil {
		return false
	}

	resp, err := client.Do(req)
	if err != nil {
		return false
	}

	data, _ := ioutil.ReadAll(resp.Body)
	idx := strings.Index(string(data), "百度一下，你就知道")
	if idx < 0 {
		return false
	}

	return true
}

func main() {
	auth, err := readConf()
	if err != nil {
		log.Println("读取配置文件出错：", err)
		os.Exit(1)
	}

	tr := &http.Transport{
		TLSClientConfig: &tls.Config{InsecureSkipVerify: true},
	}

	client = &http.Client{Transport: tr,
		Timeout: 20 * time.Second,
	}

	if err := connect(auth); err != nil {
		log.Println("登陆失败：", err)
	} else {
		log.Println("登陆成功")
	}

	for {

		if !Check() {
			log.Println("重新连接 Wi-Fi")
			if err := connect(auth); err != nil {
				log.Println("登陆失败：", err)
			} else {
				log.Println("登陆成功")
			}
		} else {
			log.Println("Wi-Fi 连接正常")
		}

		time.Sleep(10 * time.Second)
	}

	os.Exit(0)
}