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C# 關(guān)于爬取網(wǎng)站數(shù)據(jù)遇到csrf-token的分析與解決

更新時(shí)間：2021年01月28日 08:45:51 作者：yibey

這篇文章主要介紹了C# 關(guān)于爬取網(wǎng)站數(shù)據(jù)遇到csrf-token的分析與解決,幫助大家更好的理解和學(xué)習(xí)c#，感興趣的朋友可以了解下

需求

某航空公司物流單信息查詢，是一個(gè)post請(qǐng)求。通過后臺(tái)模擬POST HTTP請(qǐng)求發(fā)現(xiàn)無法獲取頁面數(shù)據(jù)，通過查看航空公司網(wǎng)站后，發(fā)現(xiàn)網(wǎng)站使用避免CSRF攻擊機(jī)制，直接發(fā)揮40X錯(cuò)誤。

關(guān)于CSRF

讀者自行百度

網(wǎng)站HTTP請(qǐng)求分析

Headers

Form Data

在head里包含了cookie 與 x-csrf-token formdata 里包含了_csrf （與head里的值是一樣的）.

這里通過查看該網(wǎng)站的JS源代碼發(fā)現(xiàn)_csrf 來自于網(wǎng)頁的head標(biāo)簽里

猜測(cè)cookie與 x-csrf-token是有一定的有效期，并且他們共同作用來防御CSRF攻擊。

解決方案

1，首先請(qǐng)求一下該航空公司的網(wǎng)站，獲取cookie與_csrf

2，然后C# 模擬http分別在head和formdata里加入如上參數(shù)，發(fā)起請(qǐng)求

代碼

public class CSRFToken
 {
 string cookie;//用于請(qǐng)求的站點(diǎn)的cookie
 List<string> csrfs;//用于請(qǐng)求站點(diǎn)的token的key 以及 value

 public CSRFToken(string url)
 {
  //校驗(yàn)傳輸安全
  if (!string.IsNullOrWhiteSpace(url))
  {
  try
  {
   //設(shè)置請(qǐng)求的頭信息.獲取url的host
   var _http = new HttpHelper(url);
   string cookie;
   string html = _http.CreateGetHttpResponseForPC(out cookie);
   this.cookie = cookie;

   string headRegex = @"<meta name=""_csrf.*"" content="".*""/>";

   MatchCollection matches = Regex.Matches(html, headRegex);
   Regex re = new Regex("(?<=content=\").*?(?=\")", RegexOptions.None);
   csrfs = new List<string>();
   foreach (Match math in matches)
   {

   MatchCollection mc = re.Matches(math.Value);
   foreach (Match ma in mc)
   {
    csrfs.Add(ma.Value);
   }
   }

  }
  catch (Exception e)
  {

  }
  }
 }

 public String getCookie()
 {
  return cookie;
 }
 public void setCookie(String cookie)
 {
  this.cookie = cookie;
 }
 public List<string> getCsrf_token()
 {
  return csrfs;
 }
 }

httpHelper

public string CreatePostHttpResponse(IDictionary<string, string> headers, IDictionary<string, string> parameters)
  {
   HttpWebRequest request = null;
   //HTTPSQ請(qǐng)求 
   UTF8Encoding encoding = new System.Text.UTF8Encoding();
   ServicePointManager.ServerCertificateValidationCallback = new RemoteCertificateValidationCallback(CheckValidationResult);
   request = WebRequest.Create(_baseIPAddress) as HttpWebRequest;
   request.ProtocolVersion = HttpVersion.Version10;
   ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12 | SecurityProtocolType.Tls11;
   request.Method = "POST";
   request.ContentType = "application/x-www-form-urlencoded";
   // request.ContentType = "application/json";
   request.UserAgent = DefaultUserAgent;
   //request.Headers.Add("X-CSRF-TOKEN", "bc0cc533-60cc-484a-952d-0b4c1a95672c");
   //request.Referer = "https://www.asianacargo.com/tracking/viewTraceAirWaybill.do";

   //request.Headers.Add("Origin", "https://www.asianacargo.com");
   //request.Headers.Add("Cookie", "JSESSIONID=HP21d2Dq5FoSlG4Fyw4slWwHb0-Sl1CG6jGtj7HE41e5f4aN_R1p!-435435446!117330181");
   //request.Host = "www.asianacargo.com";


   if (!(headers == null || headers.Count == 0))
   {

    foreach (string key in headers.Keys)
    {
     request.Headers.Add(key, headers[key]);
    }

   }


   //如果需要POST數(shù)據(jù)  
   if (!(parameters == null || parameters.Count == 0))
   {
    StringBuilder buffer = new StringBuilder();
    int i = 0;
    foreach (string key in parameters.Keys)
    {
     if (i > 0)
     {
      buffer.AppendFormat("&{0}={1}", key, parameters[key]);
     }
     else
     {
      buffer.AppendFormat("{0}={1}", key, parameters[key]);
     }
     i++;
    }
    byte[] data = encoding.GetBytes(buffer.ToString());
    using (Stream stream = request.GetRequestStream())
    {
     stream.Write(data, 0, data.Length);
    }
   }

   HttpWebResponse response;

   try
   {
    //獲得響應(yīng)流
    response = (HttpWebResponse)request.GetResponse();
    Stream s = response.GetResponseStream();

    StreamReader readStream = new StreamReader(s, Encoding.UTF8);
    string SourceCode = readStream.ReadToEnd();
    response.Close();
    readStream.Close();
    return SourceCode;
   }
   catch (WebException ex)
   {
    response = ex.Response as HttpWebResponse; return null;
   }

  }

 public string CreateGetHttpResponse(out string cookie)
  {
   HttpWebRequest request = null;
   //HTTPSQ請(qǐng)求 
   UTF8Encoding encoding = new System.Text.UTF8Encoding();
   ServicePointManager.ServerCertificateValidationCallback = new RemoteCertificateValidationCallback(CheckValidationResult);
   request = WebRequest.Create(_baseIPAddress) as HttpWebRequest;
   request.ProtocolVersion = HttpVersion.Version10;
   ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12 | SecurityProtocolType.Tls11;
   request.Method = "GET";
   request.ContentType = "application/x-www-form-urlencoded";
   request.UserAgent = DefaultUserAgent;

   HttpWebResponse response;

   try
   {
    //獲得響應(yīng)流
    response = (HttpWebResponse)request.GetResponse();

    cookie = response.Headers["Set-Cookie"];
    Stream s = response.GetResponseStream();

    StreamReader readStream = new StreamReader(s, Encoding.UTF8);
    string SourceCode = readStream.ReadToEnd();
    response.Close();
    readStream.Close();
    return SourceCode;
   }
   catch (WebException ex)
   {
    response = ex.Response as HttpWebResponse;
    cookie = "";
    return null;
   }

  }

爬取程序

爬取結(jié)果

瀏覽器結(jié)果

注意事項(xiàng)與結(jié)論

1，不同的網(wǎng)站，獲取cstf的方式不一樣，無論怎么做，只要信息傳到前臺(tái)我們都可以有相應(yīng)的方法來獲取。

2，請(qǐng)求時(shí)候的http驗(yàn)證可能不一樣，測(cè)試的某航空公司物流信息的時(shí)候，http請(qǐng)求的安全協(xié)議是tis12。

ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12 | SecurityProtocolType.Tls11; 還有其他參數(shù)比如UserAgent后臺(tái)可能也會(huì)驗(yàn)證

3,基于如上航空公司，發(fā)現(xiàn)它的cookie和cstf_token一定時(shí)間內(nèi)不會(huì)改變，那么當(dāng)實(shí)際爬取的時(shí)候可以考慮緩存cookie以及cstf_token,只有當(dāng)請(qǐng)求失敗的時(shí)候，才重新獲取

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