Question

我尝试从Fast and Furious质询中解决名为Break In 2017的任务。

任务很简单。需要HTTP回发HTML页面中包含的数学表达式的结果。它可以通过这个python脚本来实现：

import requests
import re

url = 'https://felicity.iiit.ac.in/contest/extra/fastandfurious/'
s = requests.Session()
r = s.get(url)
print(r.text)
m = re.search('\(.*\)', r.text)
while m:
    ans = eval(m[0])
    print(m[0] + ' -> ' + str(ans))
    r = s.post(url, data={'ques_ans' : ans})
    print(r.text)
    if ('the_flag_is_' in r.text): break
    m = re.search('\(.*\)', r.text)

我想在C＃中做同样的事情。我试过这样：

using System;
using System.Data;
using System.IO;
using System.Net;
using System.Text;
using System.Text.RegularExpressions;

class Program
{
    static CookieContainer cookies = new CookieContainer();

    static HttpWebRequest Create(string url)
    {
        var request = (HttpWebRequest)WebRequest.Create(url);
        request.CookieContainer = cookies;
        request.Accept = "*/*";
        request.AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate;
        request.UserAgent = "dummy";
        return request;
    }

    static string Get(string url)
    {
        var request = Create(url);
        request.Method = "GET";

        using (var response = request.GetResponse())
        using (var reader = new StreamReader(response.GetResponseStream()))
        {
            return reader.ReadToEnd();
        }
    }

    static string Post(string url, string postData)
    {
        var request = Create(url);
        request.Method = "POST";

        var data = Encoding.UTF8.GetBytes(postData);
        request.ContentType = "application/x-www-form-urlencoded";
        request.ContentLength = data.Length;

        using (var stream = request.GetRequestStream())
        {
            stream.Write(data, 0, data.Length);
        }

        using (var response = request.GetResponse())
        using (var reader = new StreamReader(response.GetResponseStream()))
        {
            return reader.ReadToEnd();
        }
    }

    static string Eval(string expression)
    {
        DataTable dt = new DataTable();
        return dt.Compute(expression, "").ToString();
    }

    static void Main()
    {
        string url = "https://felicity.iiit.ac.in/contest/extra/fastandfurious";
        string text = Get(url);
        Console.WriteLine(text);
        var m = Regex.Match(text, @"\(.*\)");

        while (m.Success)
        {
            var ans = Eval(m.Value);
            Console.WriteLine(m.Value + " -> " + ans);
            text = Post(url, "ques_ans=" + ans);
            Console.WriteLine(text);
            if (text.Contains("the_flag_is_")) break;
            m = Regex.Match(text, @"\(.*\)");
        }
    }
}

但它不起作用，因为我总是回到'1级'问题。我使用HttpWebRequest.CookieContainer属性在不同的请求中重用cookie以保持会话。

我不知道是什么问题。也许会议不起作用。或许HttpWebRequest太慢，无法及时回发结果。

如何用C＃解决这个自动化任务？

Answer 1

您的代码未经处理重定向。观察流量，我们可以看到这个特定的服务器希望你的请求/ fastandfurious以尾随斜杠结束。所以改变＆＃39; ../ fastandfurious＆＃39;到＆＃39; ../ fastandfurious /＆＃39;这将解决它。

如何解决C＃中“Break in 2017”挑战中的“速度与激情”任务？

1 个答案: