[CMIS-902] XmlException: For security reasons DTD is prohibited in this XML document

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: DotCMIS 0.6
• Fix Version/s: DotCMIS 0.7
• Component/s: dotcmis
• Labels: patch

Environment

SharePoint Server 2013
Documentum 6.7 SP1

• Assignee: Florian Müller
• Reporter: Nicolas Raoul
• Created: 19/Mar/15 08:24
• Updated: 31/Mar/15 00:25
• Resolved: 30/Mar/15 14:59

Description

Hello DotCMIS,

Many people using SharePoint Server 2013 are reporting this error when performing a simple listing of a folder:

DotCMIS.Exceptions.CmisConnectionException: Parsing exception! ---> System.Xml.XmlException: For security reasons DTD is prohibited in this XML document. To enable DTD processing set the DtdProcessing property on XmlReaderSettings to Parse and pass the settings into XmlReader.Create method.
at System.Xml.XmlTextReaderImpl.Throw(Exception e)
at System.Xml.XmlTextReaderImpl.ThrowWithoutLineInfo(String res)
at System.Xml.XmlTextReaderImpl.ParseDoctypeDecl()
at System.Xml.XmlTextReaderImpl.ParseDocumentContent()
at System.Xml.XmlTextReaderImpl.Read()
at System.Xml.XmlReader.MoveToContent()
at System.Xml.XmlReader.IsStartElement()
at DotCMIS.Binding.AtomPub.AtomPubParser.Parse()
at DotCMIS.Binding.AtomPub.AbstractAtomPubService.Parse[T](Stream stream)

The problem is easily fixed by adding `settings.DtdProcessing = DtdProcessing.Ignore;` in the Parse() method of atompub-parser.cs as seen in this commit: https://github.com/aegif/chemistry-dotcmis/commit/ee7e5931b8c8cdfcbbd280a1fb4956a8fcc895b8

Full explanation and a note about DDOS (I don't think DotCMIS should be too worried about DDOS, as it is mostly a client-side library): http://stackoverflow.com/a/28459398/226958

Thank you!
Nicolas