论坛等交互模块适用的危险字符过滤的类

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script过滤还是对html进行过滤？
/// </summary>
[Flags()]
public enum FilterType
{
Script = 1,
Html =2,
Object=3,
AHrefScript=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.Script:
filterContent=FilterScript(filterContent);
break;
case FilterType.Html:
filterContent=FilterHtml(filterContent);
break;
case FilterType.Object:
filterContent=FilterObject(filterContent);
break;
case FilterType.AHrefScript:
filterContent=FilterAHrefScript(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 FilterScript(string content)
{
string commentPattern = @"(?'comment'<!--.*?--[ /n/r]*>)" ;
string embeddedScriptComments = @"(///*.*?/*//|////.*?[/n/r])" ;
string scriptPattern = String.Format(@"(?'script'<[ /n/r]*script[^>]*>(.*?{0}?)*<[ /n/r]*/script[^>]*>)", embeddedScriptComments ) ;
// 包含注释和Script语句
string pattern = String.Format(@"(?s)({0}|{1})", commentPattern, scriptPattern) ;

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

private static string StripScriptAttributesFromTags( 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'javascript[^'"">]+)
(/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 FilterAHrefScript(string content)
{
string newstr=FilterScript(content);
string regexstr=@" href[ ^=]*= *[/s/S]*script *:";
return Regex.Replace(newstr,regexstr,string.Empty,RegexOptions.IgnoreCase);
}

public static string FilterSrc(string content)
{
string newstr=FilterScript(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=FilterScript(content);
string *include]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=FilterScript(content);
string regexstr=@"<[^>]*>";
return Regex.Replace(newstr,regexstr,string.Empty,RegexOptions.IgnoreCase);
}

public static string FilterObject(string content)
{
string [url=mailto:regexstr=@%22(?i)])*>(/w|/W)*])*>(/w|/W)*])*>(/w|/W)*