Problem validation a XML file with a local DTD file in C#

Question

I'm triying to validate a XML file. I'm using this code

XmlReaderSettings settings = new XmlReaderSettings();
settings.ProhibitDtd = false;
settings.ValidationType = ValidationType.DTD;

settings.ValidationEventHandler += new ValidationEventHandler(validationError);        

XmlSchemaSet schemas = new XmlSchemaSet();
settings.Schemas = schemas;
XmlReader reader = XmlReader.Create(lblXmlPath.Text, settings);

reader.Settings.Schemas.Add(null, lblDTDPath.Text);
while (reader.Read())
{ 
          // empty by now
}
reader.Close();

But in the line "reader.Settings.Schemas.Add(null, lblDTDPath.Text);" Visual Studio show me that error "For security reasons DTD is prohibited in this XML document. To enable DTD processing set the ProhibitDtd property on XmlReaderSettings to false and pass the settings into XmlReader.Create method"

As you can see in the code, ProhibitDtd is setted to false (I verified during debug too). I also tried to add the Schema before call to XmlReader.Create() with no success.

Answer 1

From my poking around the only way i could get it to work is not to add the schema to the XmlReader. The DTD specified in the xml document must be a valid url and the XmlReader will download it each time.

If you need the shema to be local, you can change the url of the DTD to point to a local file using a regular expression so it would look somthing like

<!DOCTYPE wml PUBLIC "-//WAPFORUM//DTD WML 1.3//EN" "file:C:\wml.dtd">

Note the file: in the url. Do this in memory before passing it to the XmlReader and that way you do not have to modify the xml file just to varify that it is correct.

Answer 2

Try adding to your DTD schema to schemas collection before the call to XmlReader.Create.

XmlReaderSettings settings = new XmlReaderSettings();
settings.ProhibitDtd = false;
settings.ValidationType = ValidationType.DTD;

settings.ValidationEventHandler += new ValidationEventHandler(validationError);        

XmlSchemaSet schemas = new XmlSchemaSet();

schemas.Add(null, lblDTDPath.Text);
settings.Schemas = schemas;

XmlReader reader = XmlReader.Create(lblXmlPath.Text, settings);

while (reader.Read())
{ 
          // empty by now
}
reader.Close();

Answer 3

I had a similar problem. The answer, for me, was that the DTD dosn't need to be hooked up via the Schemas as the xml file points to ut,

Adding via schemas caused me the issue.