PRB: Parsing XML Containing Invalid Character May Raise ArgumentException

• 0x13 is outside the valid range of XML characters, therefore an XmlException is raised. The following are valid characters:
  #x9 | #xA | #xD | [#x20-#xD7FF] | [#xE000-#xFFFD] | [#x10000-#x10FFFF]
• 0xE9 is a valid XML character, however, it is beyond the range that is defined by the US-ASCII encoding. Therefore, an ArgumentException is raised.

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Steps to Reproduce the Behavior

1. In Microsoft Visual Studio .NET, create a new Microsoft Visual Basic .NET Console Application project.
2. Paste the following code in the code window:

   Imports System.Xml
   Imports System.IO
   
   Module Module1
   
       Sub Main()
           Dim xDoc As XmlDocument = New XmlDocument()
   
           'Create XML string containing invalid XML character 0x13
           Dim badData As String = "<?xml version='1.0'?>" & _
                                   "<Data>" & Chr(19) & "</Data>"
   
           'Create byte to insert into stream, set byte equal to 
           'invalid US - ASCII character 0xE9
           Dim byteval As Byte = Byte.Parse("233")
   
   
           Dim stream As MemoryStream = New MemoryStream()
   
           'Create objects that will generate stream. You must use BinaryWriter to insert the invalid character, because StreamWriter would
           'insert a unicode character.  
           Dim swriter As StreamWriter = New StreamWriter(stream, System.Text.Encoding.ASCII)
           Dim bwriter As BinaryWriter = New BinaryWriter(stream, System.Text.Encoding.ASCII)
   
           'Write the first part of the XML instance to the stream.
           swriter.Write("<?xml version='1.0'?>" & _
                                   "<Data>")
           swriter.Flush()
   
           'Write invalid character to stream.
           bwriter.Write(byteval)
           bwriter.Flush()
   
           'Write the rest of the XML to the stream.
           swriter.Write("</Data>")
           swriter.Flush()
           stream.Position = 0
   
           Try
               'Demonstrate an XmlException being raised.
               xDoc.LoadXml(badData)
               Console.Write(xDoc.OuterXml)
           Catch xmlEx As XmlException
               Console.WriteLine("This is an XmlException: " & xmlEx.Message)
           Catch argEx As ArgumentException
               Console.WriteLine("This is an ArgumentException: " & argEx.Message)
           End Try
   
           Try
               'Demonstrate an ArgumentException being raised.
               xDoc.Load(stream)
               Console.Write(xDoc.OuterXml)
           Catch xmlEx As XmlException
               Console.WriteLine("This is an XmlException: " & xmlEx.Message)
           Catch argEx As ArgumentException
               Console.WriteLine("This is an ArgumentException: " & argEx.Message)
           End Try
   
           Console.ReadLine()
       End Sub
   
   End Module
   					

3. Run the application.

This is an XmlException: '', hexadecimal value 0x13, is an invalid character. Line 1, position 28.
				

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