DTD prohibited in xml document exception

Question

I'm getting this error when trying to parse through an XML document in a C# application:

"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."

For reference, the exception occurred at the second line of the following code:

using (XmlReader reader = XmlReader.Create(uri))
{
    reader.MoveToContent(); //here

    while (reader.Read()) //(code to parse xml doc follows).

My knowledge of Xml is pretty limited and I have no idea what DTD processing is nor how to do what the error message suggests. Any help as to what may be causing this and how to fix it? thanks...

Answer 1

Note that settings.ProhibitDtd is now obsolete, use DtdProcessing instead: (new options of Ignore, Parse, or Prohibit)

XmlReaderSettings settings = new XmlReaderSettings();
settings.DtdProcessing = DtdProcessing.Parse;

and as stated in this post: How does the billion laughs XML DoS attack work?

you should add a limit to the number of characters to avoid DoS attacks:

XmlReaderSettings settings = new XmlReaderSettings();
settings.DtdProcessing = DtdProcessing.Parse;
settings.MaxCharactersFromEntities = 1024;