Question

我正在编写一个HTTPModule，它将搜索网页中的所有mailto链接，混淆电子邮件地址和尾随参数，然后将新混淆的字符串放回HTML文档中。然后，我使用一点JavaScript来对浏览器中的mailto链接进行取消混淆，以便在用户单击链接时它能正常运行。

到目前为止，我已成功地对信息进行了模糊处理和非模糊处理，没有任何问题。我遇到的问题是将混淆的字符串放回流中。如果mailto链接仅在文档中出现一次，那么它会完美地将混淆的字符串放在mailto链接的位置，但如果有多个mailto链接，则字符串的放置看似随机。我很确定它与正则表达式匹配索引的位置有关，因为函数循环匹配并且基本上增加了通过流的HTML的长度。我将在这里发布一些经过策略编辑的代码，看看是否有人知道如何正确定位混淆字符串的位置。

我也发布了我做的工作来混淆字符串，希望它可以帮助某人尝试做同样的事情。

public override void Write(byte[] buffer, int offset, int count)
  {
      byte[] data = new byte[count];
      Buffer.BlockCopy(buffer, offset, data, 0, count);
      string html = System.Text.Encoding.Default.GetString(buffer);

      //--- Work on the HTML from the page. We want to pass it through the 
      //--- obfusication function before it is sent to the browser.
      html = html.Replace(html, obfuscate(html));

      byte[] outdata = System.Text.Encoding.Default.GetBytes(html);
      _strmHTML.Write(outdata, 0, outdata.GetLength(0));
  }


protected string obfuscate(string input)
    {

      //--- Declarations
      string email = string.Empty;
      string obsEmail = string.Empty;
      string matchedEMail = string.Empty;
      int matchIndex = 0;
      int matchLength = 0;

      //--- This is a REGEX to grab any "a href=mailto" tags in the document.
      MatchCollection matches = Regex.Matches(input, @"<a href=""mailto:[a-zA-Z0-9\.,|\-|_@?= &]*"">", RegexOptions.Singleline | RegexOptions.IgnoreCase);

      //--- Because of the nature of doing a match search with regex, we must now loop through the results
      //--- of the MatchCollection.
        foreach (Match match in matches)
        {

            //--- Get the match string
            matchedEMail = match.ToString();
            matchIndex = match.Index;
            matchLength = match.Length;

            //--- Obfusicate the matched string.
            obsEmail = obfusucateEmail(@match.Value.ToString());

           //--- Reform the entire HTML stream. THis has to be added back in at the right point.
           input = input.Substring(0, matchIndex) + obsEmail + input.Substring(matchIndex + matchLength);                 
        }

      //--- Return the obfuscated result.
      return input;
    }



protected string obfusucateEmail(string input)
  {

      //--- Declarations
      string email = string.Empty;
      string obsEmail = string.Empty;

      //--- Reset these value, in case we find more than one match.
      email = string.Empty;
      obsEmail = string.Empty;

      //--- Get the email address out of the array
      email = @input;

      //--- Clean up the string. We need to get rid of the beginning of the tag, and the end >. First,
      //--- let's flush out all quotes.
      email = email.Replace("\"", "");

      //--- Now, let's replace the beginning of the tag.
      email = email.Replace("<a href=mailto:", "");

      //--- Finally, let's get rid of the closing tag.
      email = email.Replace(">", "");


      //--- Now, we have a cleaned mailto string. Let's obfusicate it.
      Array matcharray = email.ToCharArray();

      //--- Loop through the CharArray and encode each letter.
      foreach (char letter in matcharray)
      {
          //Convert each letter of the address to the corresponding ASCII code.
          //Add XX to each value to break the direct ASCII code to letter mapping. We'll deal
          // with subtracting XX from each number on the JavaScript side.
          obsEmail += Convert.ToInt32((letter) + 42).ToString() + "~";
      }

      //--- Before we return the obfusicated value, we need to reform the tag.
      //--- Remember, up above, we stripped all this out. Well now, we need 
      //--- to add it again.
      obsEmail = "<a href=\"mailto:" + obsEmail + "\">";

      return obsEmail;
  }

我很感激任何想法！

谢谢，麦克

Answer 1

您可以做的另一件事是在正则表达式中使用匹配评估器....

protected string ObfuscateUsingMatchEvaluator(string input)
{
            var re = new Regex(@"<a href=""mailto:[a-zA-Z0-9\.,|\-|_@?= &]*"">",            RegexOptions.IgnoreCase | RegexOptions.Multiline);
            return re.Replace(input, DoObfuscation);

}

protected string DoObfuscation(Match match)
{
       return obfusucateEmail(match.Value);
}

Answer 2

根据您的性能需求（取决于您的文档大小等），您可以考虑使用HTML Agility Pack代替正则表达式来解析和操作HTML。您可以使用Linq to Objects或XPath来识别所有mailto标记。

您应该能够修改以下示例（来自the codeplex wiki page）以查找mailto标记：

HtmlDocument doc = new HtmlDocument();
 doc.Load("file.htm");
 foreach(HtmlNode link in doc.DocumentElement.SelectNodes("//a[@href"])
 {
    HtmlAttribute att = link["href"];
    if (att.Value.StartsWith("mailto:") EncryptValue(att);
 }
 doc.Save("file.htm");

HTTPModule问题：替换页面上的文本渲染

2 个答案: