微信二维码登录中的JS代码分析

在很多地方就是都出现了使用二维码登录，二维码付款，二维码账户等应用(这里的二维码种马，诈骗就不说了)，二维码验证，多终端辅助授权应用开始多起来，这里先说下啥是二维码，其实二维码就是存了二进制数据的黑白图片，当出现要求二维码登录的时候，服务器会生成一条临时的唯一的二维码信息，发送到客户端以二维码(图片)的形式写入到网页，然后你就会看到统一的四个方形的二维码，如果做的好这个二维码信息应该是有时效的，这里暂且不考虑这些，就简单的微信登录作为例子看看吧,

首先说下整个授权流程：

在客户端网页中会不断向服务器发送https连接，并且这里传输很少的数据之后就断开连接了，下面看下微信网页中这个login1c709c.js文件：

(function($, _aoWin) {
_aoWin.QRLogin = {};
  _aoWin.LoginLog = "";
 var _sBaseHost = "",
    _oLoginQrCodeImg = document.getElementById("loginQrCode");
 if (document.domain == "qq.com") {
 _sBaseHost = "weixin.qq.com";
 } else if(location.hostname.match(/(wechat\.com)$/)){
 _sBaseHost = "wechat.com";
 }else{
    _sBaseHost = "wechatapp.com";
  }
 
 var show_tip = 1,
 _sCurUUId,
 _oResetTimeout,
    _aWebMMCallbacks = [],
    _oDetactWebMMInterval = setInterval(function(){
      if(_aoWin.WebMM){
        clearInterval(_oDetactWebMMInterval);
        var callback;
        while(callback = _aWebMMCallbacks.shift()){
          if(typeof(callback) != "function") continue;
          callback();
        }
      }
    }, 1000);

function _logInPage(_asLog){
    _aoWin.LoginLog = LoginLog + _asLog + "\n";
  }
 
  function _afterLoadWebMMDo(callback){
    if(!_aoWin.WebMM){
      _aWebMMCallbacks.push(callback);
    }else{
      callback();
    }
  }
 
  function _reportNow(text){
    _logInPage(text);
    _afterLoadWebMMDo(function(){
      WebMM.ossLog({Text: text});
      WebMM.flushOssLog();
    });
  }
 
  var reLoadQRImgCount = 0,
    loadQRCodeTime = 0,
    loadQRImgSucc = function(){
      clearInterval(loadQRImgWatchDog);
      _logInPage("Load QRCode Success, time=" + (new Date().getTime() - loadQRCodeTime) + "ms, reload count: " + reLoadQRImgCount);
    },
    loadQRImgFail = function(img){
      _reportNow("Load QRcode fail!" + status + ", src: " + img.src + ", time: " + (new Date().getTime() - loadQRCodeTime) + "ms");
    },
    loadQRImgWatchDog = null;
 function _loadQRImg(uuid) {
    _poll(uuid);
    _logInPage("Load QRCode Start");
    loadQRCodeTime = new Date().getTime();
 
    _oLoginQrCodeImg.onload = function(){
      loadQRImgSucc();
      _oLoginQrCodeImg.onload = null;
    };
    _oLoginQrCodeImg.onerror = function(){loadQRImgFail(this)};
    _oLoginQrCodeImg.src = "https://login."+_sBaseHost+"/qrcode/"+uuid+"?t=webwx";
 
    loadQRImgWatchDog = setInterval(function(){
      if (reLoadQRImgCount >= 5) {
        _reset();
        return;
      }
      reLoadQRImgCount++;
 
      var _img = new Image();
      _img.onload = function () {
        if(!_oLoginQrCodeImg.onload) return;
 
        _oLoginQrCodeImg.onload = null;
        _oLoginQrCodeImg.src = this.src;//replace
        loadQRImgSucc();
      };
      _img.onerror = function(){loadQRImgFail(this)};
      _img.src = _oLoginQrCodeImg.src + "&r=" + new Date().getTime();
    }, 5000);
  }
 
  var _sSecondRequestTime = 0,
    _nAjaxTimeout = 100 * 1000,
    _nNewLoginFuncErrCount = 0;
 function _poll(_asUUID) {
 var _self = arguments.callee,
      _nTime = 0;
 _sCurUUId = _asUUID;
 
    _logInPage("_poll Request Start, time: " + new Date().getTime());
    _nTime = new Date().getTime();
 $.ajax({
 type: "GET",
 url: "https://login." + _sBaseHost + "/cgi-bin/mmwebwx-bin/login?uuid=" + _asUUID + "&tip=" + show_tip,
 dataType: "script",
 cache: false,
 timeout: _nAjaxTimeout,
 success: function(data, textStatus, jqXHR) {
      _logInPage("_poll Request Success, code: " + window.code + ", time: " + (new Date().getTime() - _nTime) + "ms");
  switch (_aoWin.code) {
  case 200:
   _sSecondRequestTime = new Date().getTime() - _sSecondRequestTime;
        _logInPage("Second Request Success, time: " + _sSecondRequestTime + "ms");
  clearTimeout(_oResetTimeout);
 
        var _fNewLoginFunc = function(){
          $.ajax({
            url: _aoWin.redirect_uri + "&fun=new",//new login page
            type: "GET",
            success:function(msg) {
              _logInPage("new func reponse, reponseMsg: " + msg);
              var code = msg.match(/<script>(.*)<\/script>/);
              var skey=msg.match(/<skey>(.*)<\/skey>/);
              if(code){
                eval(code[1]);
              }else{
                $("#container").show();
                $("#login_container").hide();
              }
              if(skey && skey[1]){
               WebMM.model("account").setSkey(skey[1]);
              }
            },
            error:function(jqXHR, textStatus, errorThrown){
              _nNewLoginFuncErrCount++;
              if(_nNewLoginFuncErrCount > 5){
                if(confirm("Call new login page func error, refresh?")){location.reload()}
                return;
              }
              _reportNow(_aoWin.redirect_uri + " New login page func error: " + textStatus +" retryCount:" + _nNewLoginFuncErrCount);
              setTimeout(_fNewLoginFunc, 500);
            }
          });
        };
        _fNewLoginFunc();
 
        _reportNow("/cgi-bin/mmwebwx-bin/login, Second Request Success, uuid: " + _asUUID + ", time: " + _sSecondRequestTime + "ms");
  break;
 
  case 201:
        clearTimeout(_oResetTimeout);
  show_tip = 0;
  $(&#39;.errorMsg&#39;).hide();
  $(&#39;.normlDesc&#39;).hide();
  $(&#39;.successMsg&#39;).show();
        _reportNow("/cgi-bin/mmwebwx-bin/login, First Request Success, uuid: " + _asUUID);
        _reportNow("/cgi-bin/mmwebwx-bin/login, Second Request Start, uuid: " + _asUUID);
 
        _sSecondRequestTime = new Date().getTime();
 
        //_nAjaxTimeout = 5 * 1000;
        _self(_asUUID);
        break;
 
  case 408:
  setTimeout(function(){
   _self(_asUUID);
  }, 500);
  break;
 
  case 400:
  case 500:
        _reset();
        _afterLoadWebMMDo(function(){
   _aoWin.Log.d("500, Login Poll Svr Exception");
  });
  break;
  }
 },
 error: function(jqXHR, textStatus, errorThrown) {
  if (textStatus == &#39;timeout&#39;) {
        setTimeout(function(){
          _self(_asUUID);
        }, 500);
  } else {
        setTimeout(function(){
          _self(_asUUID);
        }, 5000);
 
        _logInPage("_poll Request Error:" + textStatus);
        _afterLoadWebMMDo(function(){
          _aoWin.Log.e("Login Poll Error:" + textStatus);
        });
  }
 }
 });
 }

var getUUIDCount = 0,
    _getUUIDWatchDog,
    _bGetUUIDSuccess = false;//ajax successִ
 function _getUUID() {
    getUUIDCount++;
    var _self = arguments.callee,
      _loadError = function(errorText){
        _reportNow("Load UUID Error! ErrorText: " + errorText + " getUUIDCount=" + getUUIDCount);
        if(getUUIDCount > 5){
          if (confirm("Load uuid error. Refresh?")) {
            location.reload();
          }
        }
        setTimeout(function(){
          _self();
        }, 500);
      };
 
    clearTimeout(_getUUIDWatchDog);
    _getUUIDWatchDog = setTimeout(function(){
      if(!_aoWin.QRLogin.code){
        _logInPage("GetUUID Timeout, WatchDog Run");
        _self();
      }
    }, 10000);
    
        $.ajax({      
          type: "GET",      
          url: "https://login." + _sBaseHost + "/jslogin?appid=wx782c26e4c19acffb&redirect_uri="+encodeURIComponent(location.protocol+"//"+location.host+"/cgi-bin/mmwebwx-bin/webwxnewloginpage")+"&fun=new&lang=" + document.lang,
           dataType: "script",
      cache: false,
      success : function(){
        clearTimeout(_getUUIDWatchDog);
        if(_bGetUUIDSuccess) return;
        if (_aoWin.QRLogin && _aoWin.QRLogin.code == 200) {
          _logInPage("GetUUID Success, UUID=" + QRLogin.uuid);
          _bGetUUIDSuccess = true;
 
          clearTimeout(_oResetTimeout);
          _oResetTimeout = setTimeout(function(){
            location.reload();//Note: Don&#39;t run _reset(). If you run _reset(), there will may have many _poll request, as they get 408 return code
          }, 5 * 60 *1000);//5 mins
 
          _loadQRImg(QRLogin.uuid);
        } else {
          var QRLoginCode = (_aoWin.QRLogin && _aoWin.QRLogin.code) ? _aoWin.QRLogin.code : "None";
          _logInPage("GetUUID Error, QRLogin.code=" + QRLoginCode);
          _loadError("QRLogin.code= " + QRLoginCode);
        }
      },
      error : function(xhr, textStatus, errorThrown){
        _logInPage("GetUUID Error, textStatus=" + textStatus);
        _loadError(textStatus);
      }
    });
 }
 
  function _reset(){
    location.reload();
  }
 
 if ($("#login_container").is(":visible") ) {
    _getUUID();
 }
 
  
 var _bHadLog = false;
 function _ossLog() {
 if (_bHadLog) return;
 _bHadLog = true;
 var _sUvid = document.cookie.match(new RegExp( "(^| )"+"webwxuvid"+"=([^;]*)(;|$)"));
    if(!_sUvid || _sUvid.length < 3) return;
    _sUvid = _sUvid[2];
 (new Image()).src = "/cgi-bin/mmwebwx-bin/webwxstatreport?funkey=indexdemo&uvid="+_sUvid+"&uuid="+_sCurUUId;
 }
 
 
 if($("img.guide").length > 0) {
 var _nTimer = 0,
  _oGuide$ = $(".guide"),
  _oGuideTrigger$ = $("#guideTrigger, #tipTrigger"),
  _oMask$ = $(".mask");
 
  function _back() {
  _nTimer = setTimeout(function() {
  _oMask$.stop().animate({opacity:0}, function(){$(".mask").hide()});
  _oGuide$.stop().animate({marginLeft:"-120px",opacity:0}, "400", "swing",function(){
   _oGuide$.hide();
  });
  }, 100);
 }
 
 /*guide*/
 _oGuide$.css({"left":"50%", "opacity":0});
 _oGuideTrigger$.css({"backgroundColor":"white", "opacity":"0"});
 _oGuideTrigger$.mouseover(function(){
  clearTimeout(_nTimer);
  _oMask$.show().stop().animate({"opacity":0.2});
  _oGuide$.css("display", "block").stop().animate({marginLeft:"+168px", opacity:1}, 900, "swing", function() {
  _oGuide$.animate({marginLeft:"+153px"}, 300);
  });
  _ossLog();
 }).mouseout(_back);
 
 _oGuide$.mouseover(function(){
  clearTimeout(_nTimer);
 }).mouseout(_back);
 }
})(jQuery, window);

细读js之后，你就会从网页客户端这边看到请求登录的一面，网页客户端每隔500毫秒就向服务器发起ssl请求，请求当前的二维码是否被其他客户端(手机)授权，如果返回结果是201，就是说明已经获取扫描二维码终端相同的账号登录授权，如果是其他情况就再隔500毫秒再循环发请求。这个过程会一直持续到二维码被扫描通过或者二维码超时(失效)为止。
 其中使用的工具有： 抓包工具 Fidller ，Chrome F12开发人员工具，注意偶然的发现，微信的客户端有一个min-webmm1cba21.js ，其中清晰可见的XSS filter规范。

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