【Python3爬虫】反反爬之破解同程旅游加密参数 antitoken

一、前言简介

在现在各个网站使用的反爬措施中,使用 JavaScript 加密算是很常用的了,通常会使用 JavaScript 加密某个参数,例如 token 或者 sign。在这次的例子中,就采取了这种措施来反爬,使用 JavaScript 加密了一个参数 antitoken,而本篇博客要写的就是如何应对和解决的。

二、站点分析

本次爬取的站点链接为: https://www.ly.com/hotel/beijing53/?spm0=10002.2001.1.0.1.4.17

等页面加载完毕后打开开发者工具,切换到 XHR 选项,然后找到如下请求:

注意到参数中有一个 antitoken,这是一个加密后的字符串 ,那要怎么得到这个加密参数 antitoken 呢?

三、破解步骤

1.搜索加密方法

在开发者工具中全局搜索 antitoken,找到名为 list-newest.js 的 JS 文件,切换到 Sources 页面,找到这个 JS 文件并打开,点击左下角的 “{}” 进行格式化便于我们进行查阅,如下图:

在这个 JS 文件中搜索 antitoken,通过查找可以定位到一个获取 antitoken 的方法,具体代码如下:

e.getantitoken = function() {     var t = $.cookie("wangba");     t && void 0 !== t || (t = (new Date).getTime().toString(),     $.cookie("wangba", t, {         path: "/",         domain: "ly.com"     }));     return (0,     r["default"])(t)  }  ;

可以看到先是要从 Cookie 中获取一个名为 wangba 字段的值,wangba ?网吧?谁知道呢。如果 wangba 为空,则重新创建一个,而创建的其实就是一个十三位的时间戳。

var t = $.cookie("wangba"); t && void 0 !== t || (t = (new Date).getTime().toString(),

在 return 那一行打上断点,然后刷新页面进行调试,跳转到 return 返回的方法,如下图:

为了知道 antitoken 是怎么生成的,我们需要知道这个函数里各个参数 n,i,o,r 的含义,所以又得继续打断点进行调试了。

首先是 n,通过代码知道 n = a(30),打断点后找到 n 参数对应的代码如下:


n = {
        rotl: function(t, e) {
            return t << e | t >>> 32 - e
        },
        rotr: function(t, e) {
            return t << 32 - e | t >>> e
        },
        endian: function(t) {
            if (t.constructor == Number)
                return 16711935 & n.rotl(t, 8) | 4278255360 & n.rotl(t, 24);
            for (var e = 0; e < t.length; e++)
                t[e] = n.endian(t[e]);
            return t
        },
        randomBytes: function(t) {
            for (var e = []; t > 0; t--)
                e.push(Math.floor(256 * Math.random()));
            return e
        },
        bytesToWords: function(t) {
            for (var e = [], a = 0, n = 0; a < t.length; a++,
            n += 8)
                e[n >>> 5] |= t[a] << 24 - n % 32;
            return e
        },
        wordsToBytes: function(t) {
            for (var e = [], a = 0; a < 32 * t.length; a += 8)
                e.push(t[a >>> 5] >>> 24 - a % 32 & 255);
            return e
        },
        bytesToHex: function(t) {
            for (var e = [], a = 0; a < t.length; a++)
                e.push((t[a] >>> 4).toString(16)),
                e.push((15 & t[a]).toString(16));
            return e.join("")
        },
        hexToBytes: function(t) {
            for (var e = [], a = 0; a < t.length; a += 2)
                e.push(parseInt(t.substr(a, 2), 16));
            return e
        },
        bytesToBase64: function(t) {
            for (var e = [], n = 0; n < t.length; n += 3)
                for (var i = t[n] << 16 | t[n + 1] << 8 | t[n + 2], r = 0; r < 4; r++)
                    8 * n + 6 * r <= 8 * t.length ? e.push(a.charAt(i >>> 6 * (3 - r) & 63)) : e.push("=");
            return e.join("")
        },
        base64ToBytes: function(t) {
            t = t.replace(/[^A-Z0-9+\/]/gi, "");
            for (var e = [], n = 0, i = 0; n < t.length; i = ++n % 4)
                0 != i && e.push((a.indexOf(t.charAt(n - 1)) & Math.pow(2, -2 * i + 8) - 1) << 2 * i | a.indexOf(t.charAt(n)) >>> 6 - 2 * i);
            return e
        }
    },

View Code

然后是 i,通过代码知道 i = a(12).utf-8,打断点后找到 i 参数对应的代码如下:

{
    stringToBytes: function(t) {
        return a.bin.stringToBytes(unescape(encodeURIComponent(t)))
    },
    bytesToString: function(t) {
        return decodeURIComponent(escape(a.bin.bytesToString(t)))
    }
}

然后是 o,通过代码知道 o = a(12).bin,打断点后找到 o 参数对应的代码如下:

{
    stringToBytes: function (t) {
        for (var e = [], a = 0; a < t.length; a++)
            e.push(255 & t.charCodeAt(a));
        return e
    }
,
    bytesToString: function (t) {
        for (var e = [], a = 0; a < t.length; a++)
            e.push(String.fromCharCode(t[a]));
        return e.join("")
    }
}

这里可以定义一个 a12,然后从其中取出相应的方法就行了。


var a12 = {
    utf8: {
        stringToBytes: function (e) {
            return a12.bin.stringToBytes(unescape(encodeURIComponent(e)))
        },
        bytesToString: function (e) {
            return decodeURIComponent(escape(a.bin.bytesToString(e)))
        }
    },
    bin: {
        stringToBytes: function (e) {
            for (var t = [], a = 0; a < e.length; a++)
                t.push(255 & e.charCodeAt(a));
            return t
        },
        bytesToString: function (e) {
            for (var t = [], a = 0; a < e.length; a++)
                t.push(String.fromCharCode(e[a]));
            return t.join("")
        }
    }
};

View Code

最后还剩一个 o 参数,通过断点调试可以定位到如下代码:

可见这个参数 o 赋值为 null 就够了。到这里为止就已经得到加密方法里的各个参数了,接下来要说的就是如何实现加密得到 antitoken。

2.实现加密方法

要实现加密方法,还需要知道一点,就是加密时传入了两个参数,一个是十三位时间戳,另一个是空值,通过调试可知,截图如下:

将前面的各个参数和方法进行整理,得到如下 JavaScript 代码:

  1 //定义antitoken
  2 function antitoken(e) {
  3     var a12 = {
  4         utf8: {
  5             stringToBytes: function (e) {
  6                 return a12.bin.stringToBytes(unescape(encodeURIComponent(e)))
  7             },
  8             bytesToString: function (e) {
  9                 return decodeURIComponent(escape(a.bin.bytesToString(e)))
 10             }
 11         },
 12         bin: {
 13             stringToBytes: function (e) {
 14                 for (var t = [], a = 0; a < e.length; a++)
 15                     t.push(255 & e.charCodeAt(a));
 16                 return t
 17             },
 18             bytesToString: function (e) {
 19                 for (var t = [], a = 0; a < e.length; a++)
 20                     t.push(String.fromCharCode(e[a]));
 21                 return t.join("")
 22             }
 23         }
 24     };
 25     var t = null;
 26     var n, i, o, s, r;
 27     n = {
 28         rotl: function (e, t) {
 29             return e << t | e >>> 32 - t
 30         },
 31         rotr: function (e, t) {
 32             return e << 32 - t | e >>> t
 33         },
 34         endian: function (e) {
 35             if (e.constructor == Number)
 36                 return 16711935 & n.rotl(e, 8) | 4278255360 & n.rotl(e, 24);
 37             for (var t = 0; t < e.length; t++)
 38                 e[t] = n.endian(e[t]);
 39             return e
 40         },
 41         randomBytes: function (e) {
 42             for (var t = []; e > 0; e--)
 43                 t.push(Math.floor(256 * Math.random()));
 44             return t
 45         },
 46         bytesToWords: function (e) {
 47             for (var t = [], a = 0, n = 0; a < e.length; a++,
 48                 n += 8)
 49                 t[n >>> 5] |= e[a] << 24 - n % 32;
 50             return t
 51         },
 52         wordsToBytes: function (e) {
 53             for (var t = [], a = 0; a < 32 * e.length; a += 8)
 54                 t.push(e[a >>> 5] >>> 24 - a % 32 & 255);
 55             return t
 56         },
 57         bytesToHex: function (e) {
 58             for (var t = [], a = 0; a < e.length; a++)
 59                 t.push((e[a] >>> 4).toString(16)),
 60                     t.push((15 & e[a]).toString(16));
 61             return t.join("")
 62         },
 63         hexToBytes: function (e) {
 64             for (var t = [], a = 0; a < e.length; a += 2)
 65                 t.push(parseInt(e.substr(a, 2), 16));
 66             return t
 67         },
 68         bytesToBase64: function (e) {
 69             for (var t = [], n = 0; n < e.length; n += 3)
 70                 for (var i = e[n] << 16 | e[n + 1] << 8 | e[n + 2], o = 0; o < 4; o++)
 71                     8 * n + 6 * o <= 8 * e.length ? t.push(a.charAt(i >>> 6 * (3 - o) & 63)) : t.push("=");
 72             return t.join("")
 73         },
 74         base64ToBytes: function (e) {
 75             e = e.replace(/[^A-Z0-9+\/]/gi, "");
 76             for (var t = [], n = 0, i = 0; n < e.length; i = ++n % 4)
 77                 0 != i && t.push((a.indexOf(e.charAt(n - 1)) & Math.pow(2, -2 * i + 8) - 1) << 2 * i | a.indexOf(e.charAt(n)) >>> 6 - 2 * i);
 78             return t
 79         }
 80     },
 81         i = a12.utf8,
 82         o = null,
 83         s = a12.bin,
 84         (r = function (e, t) {
 85                 e.constructor == String ? e = t && "binary" === t.encoding ? s.stringToBytes(e) : i.stringToBytes(e) : o(e) ? e = Array.prototype.slice.call(e, 0) : Array.isArray(e) || (e = e.toString());
 86                 for (var a = n.bytesToWords(e), l = 8 * e.length, c = 1732584193, d = -271733879, p = -1732584194, u = 271733878, m = 0; m < a.length; m++)
 87                     a[m] = 16711935 & (a[m] << 8 | a[m] >>> 24) | 4278255360 & (a[m] << 24 | a[m] >>> 8);
 88                 a[l >>> 5] |= 128 << l % 32;
 89                 a[14 + (l + 64 >>> 9 << 4)] = l;
 90                 var f = r._ff
 91                     , h = r._gg
 92                     , v = r._hh
 93                     , g = r._ii;
 94                 for (m = 0; m < a.length; m += 16) {
 95                     var y = c
 96                         , _ = d
 97                         , b = p
 98                         , $ = u;
 99                     d = g(d = g(d = g(d = g(d = v(d = v(d = v(d = v(d = h(d = h(d = h(d = h(d = f(d = f(d = f(d = f(d, p = f(p, u = f(u, c = f(c, d, p, u, a[m + 0], 7, -680876936), d, p, a[m + 1], 12, -389564586), c, d, a[m + 2], 17, 606105819), u, c, a[m + 3], 22, -1044525330), p = f(p, u = f(u, c = f(c, d, p, u, a[m + 4], 7, -176418897), d, p, a[m + 5], 12, 1200080426), c, d, a[m + 6], 17, -1473231341), u, c, a[m + 7], 22, -45705983), p = f(p, u = f(u, c = f(c, d, p, u, a[m + 8], 7, 1770035416), d, p, a[m + 9], 12, -1958414417), c, d, a[m + 10], 17, -42063), u, c, a[m + 11], 22, -1990404162), p = f(p, u = f(u, c = f(c, d, p, u, a[m + 12], 7, 1804603682), d, p, a[m + 13], 12, -40341101), c, d, a[m + 14], 17, -1502002290), u, c, a[m + 15], 22, 1236535329), p = h(p, u = h(u, c = h(c, d, p, u, a[m + 1], 5, -165796510), d, p, a[m + 6], 9, -1069501632), c, d, a[m + 11], 14, 643717713), u, c, a[m + 0], 20, -373897302), p = h(p, u = h(u, c = h(c, d, p, u, a[m + 5], 5, -701558691), d, p, a[m + 10], 9, 38016083), c, d, a[m + 15], 14, -660478335), u, c, a[m + 4], 20, -405537848), p = h(p, u = h(u, c = h(c, d, p, u, a[m + 9], 5, 568446438), d, p, a[m + 14], 9, -1019803690), c, d, a[m + 3], 14, -187363961), u, c, a[m + 8], 20, 1163531501), p = h(p, u = h(u, c = h(c, d, p, u, a[m + 13], 5, -1444681467), d, p, a[m + 2], 9, -51403784), c, d, a[m + 7], 14, 1735328473), u, c, a[m + 12], 20, -1926607734), p = v(p, u = v(u, c = v(c, d, p, u, a[m + 5], 4, -378558), d, p, a[m + 8], 11, -2022574463), c, d, a[m + 11], 16, 1839030562), u, c, a[m + 14], 23, -35309556), p = v(p, u = v(u, c = v(c, d, p, u, a[m + 1], 4, -1530992060), d, p, a[m + 4], 11, 1272893353), c, d, a[m + 7], 16, -155497632), u, c, a[m + 10], 23, -1094730640), p = v(p, u = v(u, c = v(c, d, p, u, a[m + 13], 4, 681279174), d, p, a[m + 0], 11, -358537222), c, d, a[m + 3], 16, -722521979), u, c, a[m + 6], 23, 76029189), p = v(p, u = v(u, c = v(c, d, p, u, a[m + 9], 4, -640364487), d, p, a[m + 12], 11, -421815835), c, d, a[m + 15], 16, 530742520), u, c, a[m + 2], 23, -995338651), p = g(p, u = g(u, c = g(c, d, p, u, a[m + 0], 6, -198630844), d, p, a[m + 7], 10, 1126891415), c, d, a[m + 14], 15, -1416354905), u, c, a[m + 5], 21, -57434055), p = g(p, u = g(u, c = g(c, d, p, u, a[m + 12], 6, 1700485571), d, p, a[m + 3], 10, -1894986606), c, d, a[m + 10], 15, -1051523), u, c, a[m + 1], 21, -2054922799), p = g(p, u = g(u, c = g(c, d, p, u, a[m + 8], 6, 1873313359), d, p, a[m + 15], 10, -30611744), c, d, a[m + 6], 15, -1560198380), u, c, a[m + 13], 21, 1309151649), p = g(p, u = g(u, c = g(c, d, p, u, a[m + 4], 6, -145523070), d, p, a[m + 11], 10, -1120210379), c, d, a[m + 2], 15, 718787259), u, c, a[m + 9], 21, -343485551),
100                         c = c + y >>> 0;
101                     d = d + _ >>> 0;
102                     p = p + b >>> 0;
103                     u = u + $ >>> 0;
104                 }
105                 return n.endian([c, d, p, u])
106             }
107         )._ff = function (e, t, a, n, i, o, s) {
108             var r = e + (t & a | ~t & n) + (i >>> 0) + s;
109             return (r << o | r >>> 32 - o) + t
110         };
111 
112     r._gg = function (e, t, a, n, i, o, s) {
113         var r = e + (t & n | a & ~n) + (i >>> 0) + s;
114         return (r << o | r >>> 32 - o) + t
115     };
116 
117     r._hh = function (e, t, a, n, i, o, s) {
118         var r = e + (t ^ a ^ n) + (i >>> 0) + s;
119         return (r << o | r >>> 32 - o) + t
120     };
121 
122     r._ii = function (e, t, a, n, i, o, s) {
123         var r = e + (a ^ (t | ~n)) + (i >>> 0) + s;
124         return (r << o | r >>> 32 - o) + t
125     };
126 
127     r._blocksize = 16;
128     r._digestsize = 16;
129 
130     var a = n.wordsToBytes(r(e, t));
131     return t && t.asBytes ? a : t && t.asString ? s.bytesToString(a) : n.bytesToHex(a);
132 }

这就是使用 JavaScript 实现的加密方法了,传入的参数 e 是一个十三位时间戳,之后无论使用 JS 还是 Python 进行调用都可以了,这里可以进行一下验证。

首先是开发者工具里的截图:

然后是代码的运行结果:

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