/// <summary>
/// Validates whether a <see cref="LocalFileSystemProvider"/> was configured
/// with access restricted to a given <see cref="LocalFileSystemProvider.RootDirectory"/>,
/// and makes sure that the requested <paramref name="resource"/> is indeed contained
/// within that folder.
/// </summary>
/// <param name="resource">The requested resource.</param>
/// <exception cref="ResourceAccessException">If the requested resource is not
/// a descendant of a configured <see cref="LocalFileSystemProvider.RootDirectory"/>.</exception>
/// <exception cref="ArgumentNullException">If <paramref name="resource"/>
/// is a null reference.</exception>
private void ValidateResourceAccess(VirtualResourceInfo resource)
{
if (resource == null)
{
throw new ArgumentNullException("resource");
}
//if there isn't a restricted custom root, every file resource can be accessed
//(if the path is invalid, this will fail later, depending on the action)
if (RootDirectory == null)
{
return;
}
try
{
string path = PathUtil.GetAbsolutePath(resource.FullName, RootDirectory);
//if the root path was submitted, we're within the scope, too
if (IsRootPath(path))
{
return;
}
//if we have a custom root, make sure the resource is indeed a descendant of the root
if (RootDirectory.IsParentOf(path))
{
return;
}
}
catch (ResourceAccessException e)
{
//just bubble a resource access exception
if (e.Resource == null)
{
e.Resource = resource;
}
throw;
}
catch (Exception e)
{
//exceptions can happen in case of invalid file paths
//log detailed info
string error = "Resource request for '{0}' caused exception when validating against root directory '{1}'.";
error = String.Format(error, resource.FullName, RootDirectory.FullName);
VfsLog.Debug(e, error);
//do not expose too much path information (e.g. absolute paths if disabled)
error = String.Format("Invalid resource path: '{0}'.", resource.FullName);
throw new ResourceAccessException(error)
{
Resource = resource
};
}
//if none of the above is true, the request is invalid
//log detailed info
string msg = "Resource request for '{0}' was blocked. The resource is outside the root directory '{1}'.";
msg = String.Format(msg, resource.FullName, RootDirectory.FullName);
VfsLog.Debug(msg);
//do not expose too much path information (e.g. absolute paths if disabled)
msg = String.Format("Invalid resource path: '{0}'.", resource.FullName);
throw new ResourceAccessException(msg)
{
Resource = resource
};
}