/// <summary>
/// Reads XML conforming to https://www.w3.org/TR/2001/PR-xmldsig-core-20010820/#sec-Transforms
/// </summary>
/// <param name="reader">a <see cref="XmlReader"/>positioned on a <Transforms> element.</param>
/// <param name="reference">a <see cref="Reference"/> to attach transforms.</param>
/// <exception cref="ArgumentNullException">if <paramref name="reader"/> is null.</exception>
/// <exception cref="ArgumentNullException">if <paramref name="reference"/> is null.</exception>
/// <exception cref="XmlReadException">if there is a problem reading the XML.</exception>
public virtual void ReadTransforms(XmlReader reader, Reference reference)
{
if (reader == null)
{
throw LogArgumentNullException(nameof(reader));
}
if (reference == null)
{
throw LogArgumentNullException(nameof(reference));
}
try
{
// <Transforms> - optional
if (!reader.IsStartElement(XmlSignatureConstants.Elements.Transforms, XmlSignatureConstants.Namespace))
{
return;
}
if (reader.IsEmptyElement)
{
reader.Read();
return;
}
reader.Read();
// <Transform> - unbounded
while (reader.IsStartElement(XmlSignatureConstants.Elements.Transform, XmlSignatureConstants.Namespace))
{
var isEmptyElement = reader.IsEmptyElement;
var algorithm = reader.GetAttribute(XmlSignatureConstants.Attributes.Algorithm);
if (string.IsNullOrEmpty(algorithm))
{
throw XmlUtil.LogReadException(LogMessages.IDX30105);
}
if (TransformFactory.IsSupportedTransform(algorithm))
{
reference.Transforms.Add(TransformFactory.GetTransform(algorithm));
reader.Read();
}
else if (TransformFactory.IsSupportedCanonicalizingTransfrom(algorithm))
{
reference.CanonicalizingTransfrom = TransformFactory.GetCanonicalizingTransform(algorithm);
reader.Read();
// release 5.2.1 did not require 'ec' ns. So, we need to accept names with and without a prefix.
if (reader.IsStartElement(XmlSignatureConstants.Elements.InclusiveNamespaces, XmlSignatureConstants.ExclusiveC14nNamespace) || reader.IsStartElement(XmlSignatureConstants.Elements.InclusiveNamespaces))
{
bool isOnEmptyElement = reader.IsEmptyElement;
reference.CanonicalizingTransfrom.InclusiveNamespacesPrefixList = reader.GetAttribute(XmlSignatureConstants.Attributes.PrefixList);
reader.ReadStartElement();
if (!isOnEmptyElement)
{
reader.ReadEndElement();
}
}
}
else
{
throw XmlUtil.LogReadException(LogMessages.IDX30210, algorithm);
}
reader.MoveToContent();
if (!isEmptyElement)
{
reader.ReadEndElement();
}
}
// </ Transforms>
reader.MoveToContent();
reader.ReadEndElement();
}
catch (Exception ex)
{
if (ex is XmlReadException)
{
throw;
}
throw XmlUtil.LogReadException(LogMessages.IDX30016, ex, XmlSignatureConstants.Elements.Transforms);
}
}
/// <summary>
/// Static constructor that initializes the default <see cref="TransformFactory"/>.
/// </summary>
static TransformFactory()
{
Default = new TransformFactory();
}
