危险字符过滤的类

*/
using System;
using System.IO;
using System.Text;
using System.Text.RegularExpressions;
using System.Runtime.Remoting;
using System.Runtime.Remoting.Proxies;
using System.Runtime.Remoting.Messaging;
using System.Reflection;

 

namespace FilterRealProxy
{
 /// <summary>
 ///  FilterRealProxy类：一个真实代理, 拦截它所代理对象中方法的返回值，并对需要过滤的返回值进行过滤。
 /// </summary>
 public class FilterRealProxy:RealProxy
 {
  private MarshalByRefObject target;
  public FilterRealProxy(MarshalByRefObject target):base(target.GetType())
  {
   this.target=target;   
  }
  public override IMessage Invoke(IMessage msg)
  {
   IMethodCallMessage callMsg=msg as IMethodCallMessage;
   IMethodReturnMessage returnMsg = RemotingServices.ExecuteMessage(target,callMsg);
   //检查返回值是否为String,如果不是String,就没必要进行过滤
   if(this.IsMatchType(returnMsg.ReturnValue))
   {
    string returnValue=this.Filter(returnMsg.ReturnValue.ToString(),returnMsg.MethodName);           
    return new ReturnMessage(returnValue,null,0,null,callMsg);
   }
   return returnMsg;
　　　　 }
  protected string Filter(string ReturnValue,string MethodName)
  {
   MethodInfo methodInfo=target.GetType().GetMethod(MethodName);
   object[] attributes=methodInfo.GetCustomAttributes(typeof(StringFilter),true);
   foreach (object attrib in attributes)
   {
    return FilterHandler.Process(((StringFilter)attrib).FilterType,ReturnValue);
   }
   return ReturnValue;
  }
  protected bool IsMatchType(object obj)
  {
   return obj is System.String;
  }
 }

 ///<summary>
 ///  StringFilter类：自定义属性类, 定义目标元素的过滤类型
 ///</summary>
 public class StringFilter:Attribute
 {
  protected FilterType _filterType;

  public StringFilter(FilterType filterType)
  {
   this._filterType=filterType;
  }
  public FilterType FilterType
  {
   get
   {
    return _filterType;
   }
  }
 }

 /// <summary>
 /// 枚举类：用于指定过滤类型，例如：对s cript过滤还是对HTML进行过滤？
 /// </summary>
 [Flags()]
 public enum FilterType
 {
  s cript = 1,
  HTML =2,
  Object=3,
  AHrefs cript=4,
  Iframe=5,
  Frameset=6,
  Src=../../7,
  Badwords=8,
  //Include=9,
  All=16
 }

 ///<summary>
 /// 过滤处理类：根据过滤类型，调用相应的过滤处理方法。
 ///</summary>
 
 public class FilterHandler
 {
  private FilterHandler()
  {
  }
  public static string Process(FilterType filterType,string filterContent)
  {
   switch(filterType)
   {
    case FilterType.s cript:
     filterContent=Filters cript(filterContent);
     break;
    case FilterType.HTML:
     filterContent=FilterHTML(filterContent);
     break;
    case FilterType.Object:
     filterContent=FilterObject(filterContent);
     break;
    case FilterType.AHrefs cript:
     filterContent=FilterAHrefs cript(filterContent);
     break;
    case FilterType.Iframe:
     filterContent=FilterIframe(filterContent);
     break;
    case FilterType.Frameset:
     filterContent=FilterFrameset(filterContent);
     break;
    case FilterType.Src:
     filterContent=FilterSrc(filterContent);
     break;
    //case FilterType.Include:
    // filterContent=FilterInclude(filterContent);
    // break;
    case FilterType.Badwords:
     filterContent=FilterBadwords(filterContent);
     break;
    case FilterType.All:
     filterContent=FilterAll(filterContent);
     break;
    default:
     //do nothing
     break;
   }
   return filterContent;
  }

  public static string Filters cript(string content)
  {
   string commentPattern = @"(?'comment'<!--.*?--[ /n/r]*>)" ;
   string embeddeds criptComments = @"(///*.*?/*//|////.*?[/n/r])" ;
   string s criptPattern = String.Format(@"(?'s cript'<[ /n/r]*s cript[^>]*>(.*?{0}?)*<[ /n/r]*/s cript[^>]*>)", embeddeds criptComments ) ;
   // 包含注释和s cript语句
   string pattern = String.Format(@"(?s)({0}|{1})", commentPattern, s criptPattern) ;

   return Strips criptAttributesFromTags(Regex.Replace(content,pattern,string.Empty,RegexOptions.IgnoreCase));
  }

  private static string Strips criptAttributesFromTags( string content )
  {
   string eventAttribs = @"on(blur|c(hange|lick)|dblclick|focus|keypress|(key|mouse)(down|up)|(un)?load
                    |mouse(move|o(ut|ver))|reset|s(elect|ubmit))" ;
   
   string pattern = String.Format(@"(?inx)
        /<(/w+)/s+
            (
                (?'attribute'
                (?'attributeName'{0})/s*=/s*
                (?'delim'['""]?)
                (?'attributeValue'[^'"">]+)
                (/3)
            )
            |
            (?'attribute'
                (?'attributeName'href)/s*=/s*
                (?'delim'['""]?)
                (?'attributeValue'javas cript[^'"">]+)
                (/3)
            )
            |
            [^>]
        )*
    />", eventAttribs ) ;
   Regex re = new Regex( pattern ) ;
   // 使用MatchEvaluator的委托
   return re.Replace( content, new MatchEvaluator( StripAttributesHandler ) ) ;
  }

  private static string StripAttributesHandler( Match m )
  {
   if( m.Groups["attribute"].Success  )
   {
    return m.Value.Replace( m.Groups["attribute"].Value, "") ;
   }
   else
   {
    return m.Value ;
   }
  }

  public static string FilterAHrefs cript(string content)
  {
   string newstr=Filters cript(content);
   string regexstr=@" href[ ^=]*= *[/s/S]*s cript *:";
   return Regex.Replace(newstr,regexstr,string.Empty,RegexOptions.IgnoreCase);
  }

  public static string FilterSrc(string content)
  {
   string newstr=Filters cript(content);
   string regexstr=@" src *= *['""]?[^/.]+/.(js|vbs|ASP|ASPx|PHP|JSP)['""]";
   return Regex.Replace(newstr,regexstr,@"",RegexOptions.IgnoreCase);
  }
/*
  public static string FilterInclude(string content)
  {
   string newstr=Filters cript(content);
   string regexstr=@"<[/s/S]*include *(file|virtual) *= *[/s/S]*/.(js|vbs|ASP|ASPx|PHP|JSP)[^>]*>";
   return Regex.Replace(newstr,regexstr,string.Empty,RegexOptions.IgnoreCase);
  }
*/
  public static string FilterHTML(string content)
  {
   string newstr=Filters cript(content);
   string regexstr=@"<[^>]*>";
   return Regex.Replace(newstr,regexstr,string.Empty,RegexOptions.IgnoreCase);
  }

  public static string FilterObject(string content)
  {
   string regexstr=@"(?i)<Object([^>])*>(/w|/W)*</Object([^>])*>";
   return Regex.Replace(content,regexstr,string.Empty,RegexOptions.IgnoreCase);
  }

  public static string FilterIframe(string content)
  {
   string regexstr=@"(?i)<Iframe([^>])*>(/w|/W)*</Iframe([^>])*>";
   return Regex.Replace(content,regexstr,string.Empty,RegexOptions.IgnoreCase);
  }

  public static string FilterFrameset(string content)
  {
   string regexstr=@"(?i)<Frameset([^>])*>(/w|/W)*</Frameset([^>])*>";
   return Regex.Replace(content,regexstr,string.Empty,RegexOptions.IgnoreCase);
  }

  //移除非法或不友好字符
  private static string FilterBadwords(string chkStr)
  {
    //这里的非法和不友好字符由你任意加，用“|”分隔，支持正则表达式,由于本Blog禁止贴非法和不友好字符，所以这里无法加上。
string BadWords=@"...";
   if (chkStr == "")
   {
    return "";
   }

   string[] bwords = Badwords.Split('#');
   int i,j;
   string str;
   StringBuilder sb = new StringBuilder();
   for(i = 0; i< bwords.Length; i++)
   {
    str=bwords[i].ToString().Trim();
    string regStr,toStr;
    regStr=str;
    Regex r=new Regex(regStr,RegexOptions.IgnoreCase | RegexOptions.Singleline| RegexOptions.Multiline);
    Match m=r.Match(chkStr);
    if(m.Success)
    {
     j=m.Value.Length;
     sb.Insert(0,"*",j);
     toStr=sb.ToString();
     chkStr=Regex.Replace(chkStr,regStr,toStr,RegexOptions.IgnoreCase | RegexOptions.Singleline| RegexOptions.Multiline);  
    }
    sb.Remove(0,sb.Length);
   }
   return chkStr;
  }

  public static string FilterAll(string content)
  {
   content = FilterHTML(content);
   content = Filters cript(content);
   content = FilterAHrefs cript(content);
   content = FilterObject(content);
   content = FilterIframe(content);
   content = FilterFrameset(content);
   content = FilterSrc(content);
   content = FilterBadwords(content);
   //content = FilterInclude(content);
   return content;
  }
 }
}