public class IdAndImgFilter : Stream
{
Stream responseStream;
StringBuilder responseHtml;
long position;
public IdAndImgFilter(Stream inputStream)
{
responseStream = inputStream;
responseHtml = new StringBuilder();
}
public override bool CanRead
{
get
{
return true;
}
}
public override bool CanSeek
{
get
{
return true;
}
}
public override bool CanWrite
{
get
{
return true;
}
}
public override void Close()
{
responseStream.Close();
}
public override void Flush()
{
responseStream.Flush();
}
public override long Length
{
get
{
return 0;
}
}
public override long Position
{
get
{
return position;
}
set
{
position = value;
}
}
public override long Seek(long offset, SeekOrigin origin)
{
return responseStream.Seek(offset, origin);
}
public override void SetLength(long length)
{
responseStream.SetLength(length);
}
public override int Read(byte[] buffer, int offset, int count)
{
return responseStream.Read(buffer, offset, count);
}
public override void Write(byte[] buffer, int offset, int count)
{
string strBuffer = System.Text.UTF8Encoding.UTF8.GetString(buffer, offset, count);
Regex eof = new Regex("</html>", RegexOptions.IgnoreCase);
if (!eof.IsMatch(strBuffer))
{
responseHtml.Append(strBuffer);
}
else
{
responseHtml.Append(strBuffer);
/*(?<=((src=)|(href=))[^><]*?)&(?!.{1,4};)
This part checks for & in href and src properties.
|((?<=<img)\\s(?![^>]*alt=))
This checks for the first space of img without alt.
|(id=\"__EVENTTARGET)|(id=\"__VIEWSTATE)|(id=\"__EVENTARGUMENT)
This is for the __ Viewstate problem.
|(\\s{0,3}/>)
This is for the self closing tags.
*/
Regex allToBeChanged = new Regex("(?<=((src=)|(href=))[^><]*?)&(?!.{1,4};)|((?<=<img)\\s(?![^>]*alt=))|(id=\"__EVENTTARGET)|(id=\"__VIEWSTATE)|(id=\"__EVENTARGUMENT)|(\\s{0,3}/>)", RegexOptions.Singleline | RegexOptions.IgnoreCase);
string finalHtml = allToBeChanged.Replace(responseHtml.ToString(), new MatchEvaluator(this.GetReplaceText));
byte[] data = System.Text.UTF8Encoding.UTF8.GetBytes(finalHtml);
responseStream.Write(data, 0, data.Length);
}
}
public string GetReplaceText(Match m)
{
string x = m.Value;
switch (x)
{
case "id=\"__EVENTTARGET":
return "id=\"EVENTTARGET";
case "id=\"__EVENTARGUMENT":
return "id=\"EVENTARGUMENT";
case "id=\"__VIEWSTATE":
return "id=\"VIEWSTATE";
case " ": // it matches the last space in a img tag that doesn't have an alt tag
return " alt=\"\" ";
case "/>":
case " />":
case " />":
case " />":
return ">";
case "&":
return "&";
}
//throw new Exception("There was no matching string, the regular expression needs fixing");
return x;
}
}