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题目

https://match.yuanrenxue.com/match/4

image-20210917162428942

抓包

https://match.yuanrenxue.com/api/match/4

image-20210917162624937

分析

image-20210917162856315

该页面每个td中img个数和实际展示个数不一致，且部分img被display: none;属性隐藏后个数一致，但img排列组合顺序和实际展示不一致，目测和style中的left属性有关。

通过抓包分析以上请求中返回的info属性，通过html格式化后，发现是多个td中包裹多个img标签，不过个数和展示的个数不一致，且src中的内容是data:image/png;base64,开头的图片转为base64形式。通过分析将对应的图片转为数字字典如下

image_dict = {
    'data:image/png;base64,iVBORw0KGgoAAAANSUh...': 0,
    'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABUAAAAd...': 6,
    'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABQAAAAdCAY...': 8,
    'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABUAAAAcCAYAAAC...': 1,
    'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABQA...': 9,
    'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABUAAAAbC...': 4,
    'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABQAAAAdCA...': 2,
    'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABQA...': 3,
    'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABQAAAAeCAYAAAAsEj5...': 7,
    'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABUAAAAcCAY...': 5
}

将格式化后的html中的base64图片转为数字

image-20210917164659843

对比得到两个结论，首先class中去除一个加密字符串的属性，且style中部分标签加上了display: none;属性。说明拿到服务端返回结果后，js中为style加上了display为none的属性。

全局搜索'display','none'或者'display', 'none'

image-20210917173431738

其中data.info就是获取返回内容中info的部分,也就是<td>标签里面的内容，通过JQuery的选择器,选择标签中有number的元素,并将<td>标签的内容添加进去，通过获取data中key和value中的值,并替换一些字符,最后经过md5算法加密,得到一串密文，在密文前面加上一个.,并赋值给变量j_key，通过选择器,选择有密文这个属性的标签,并将其样式设置成display:none,最终再删除属性中的密文

爬虫

image_dict = {
    'data:image/png;base64,iVBORw0KGgoAAAANSUh...': 0,
    'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABUAAAAd...': 6,
    'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABQAAAAdCAY...': 8,
    'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABUAAAAcCAYAAAC...': 1,
    'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABQA...': 9,
    'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABUAAAAbC...': 4,
    'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABQAAAAdCA...': 2,
    'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABQA...': 3,
    'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABQAAAAeCAYAAAAsEj5...': 7,
    'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAABUAAAAcCAY...': 5
}

answer_num_list = []


def get_base64_data(page_num):
    url = 'http://match.yuanrenxue.com/api/match/4?page={}'.format(page_num)
    headers = {
        'Host': 'match.yuanrenxue.com',
        'Pragma': 'no-cache',
        'Referer': 'http://match.yuanrenxue.com/match/4',
        'User-Agent': 'yuanrenxue.project',
        'X-Requested-With': 'XMLHttpRequest'
    }
    res = requests.get(url=url, headers=headers)
    # print(res.text)
    return res.json()['info'], res.json()['key'], res.json()['value']


def b642jpg(b64str, name):
    data = base64.b64decode(b64str)
    with open('{}.jpg'.format(name), 'wb') as f:
        f.write(data)
        print('打印完毕')


# var j_key = '.' + hex_md5(btoa(data.key + data.value).replace(/=/g, ''));
# 利用key和value计算出属性为display=none的md5索引值
def get_j_key(key, value):
    return hashlib.md5(base64.b64encode((key + value).encode()).replace(b'=', b'')).hexdigest()


# 获取td中4个图片
def parse_every_group_nums(info_data):
    pattern = re.compile(r'<td>(.*?)</td>')
    every_group_nums_list = pattern.findall(info_data)
    return every_group_nums_list


# 利用j_key和每个图片对应的hash值,确定出要被用的所有数字子图片,及其相对位置偏移值
def parse_real_use_num_info(every_group_nums, j_key):
    # 找到base64
    pattern = re.compile(r'img_number (.*?)"')
    img_number_list = pattern.findall(every_group_nums)
    # 找到图片
    pattern = re.compile(r'base64,(.*?)"')
    ba64_str_list = pattern.findall(every_group_nums)
    # 找到样式
    pattern = re.compile(r'style="(.*?)"')
    number_style_list = pattern.findall(every_group_nums)

    # 寻找所有要用的子图
    ba64_str_list = [ba64_str_list[index] for index, img_number in enumerate(img_number_list) if img_number != j_key]
    num_list = [image_dict['data:image/png;base64,' + __] for __ in ba64_str_list]

    # 匹配每个子图实际对应的偏移量 6801 -> ['0', '11.5', '-11.5', '0.0']
    number_style_list = [number_style_list[index].replace('left:', '').replace('px', '') for index, img_number in
    enumerate(img_number_list) if img_number != j_key]

    # 根据偏移值，计算真实的数字顺序
    ture_order_list = caculate_css_left(number_style_list, num_list)

    # 将每小组数字拼接并保存
    temp_num = 0
    for index, num in enumerate(ture_order_list[::-1]):
        temp_num += num * 10 ** index
    answer_num_list.append(temp_num)


# 根据图片映射的数字和图片的偏移值，计算出数字的真实顺序，列表排序返回
def caculate_css_left(number_style_list, num_list):
    # [0, 1, -1, 0]
    number_style_list = [round(float(__) / 11) for __ in number_style_list]
    # 定义数组
    ture_order_list = ['']*len(number_style_list)
    for index, number_style in enumerate(number_style_list):
        ture_order_list[int(index + number_style)] = num_list[index]
    return ture_order_list


if __name__ == '__main__':
    # info, _, __ = get_base64_data(1)
    # # <td>有10组  left有63个 display有0个，需要md5计算进行拼接base64  ed501a5e229d41330bee8399441bfbfb有39次  57feebf056bfb527e9ad8561e0694b0a有24次
    # '''
    # b642jpg(b64str, 'test')
    for page_num in range(1, 6):
        info_data, key, value = get_base64_data(page_num)
        j_key = get_j_key(key, value)
        every_group_nums_list = parse_every_group_nums(info_data)
        for every_group_nums in every_group_nums_list:
            parse_real_use_num_info(every_group_nums, j_key)
    print(sum(answer_num_list))

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