private void OpenMedia(Uri source)
{
string toOpen = null;
if (source != null && source.IsAbsoluteUri && source.Scheme == PackUriHelper.UriSchemePack)
{
try
{
source = BaseUriHelper.ConvertPackUriToAbsoluteExternallyVisibleUri(source);
}
catch (InvalidOperationException)
{
source = null;
_mediaEventsHelper.RaiseMediaFailed(new System.NotSupportedException(SR.Get(SRID.Media_PackURIsAreNotSupported, null)));
}
}
// Setting a null source effectively disconects the MediaElement.
if (source != null)
{
// keep whether we asserted permissions or not
bool elevated = false;
// get the base directory of the application; never expose this
Uri appBase = SecurityHelper.GetBaseDirectory(AppDomain.CurrentDomain);
// this extracts the URI to open
Uri uriToOpen = ResolveUri(source, appBase);
// access is allowed in the following cases (only 1 & 2 require elevation):
// 1) to any HTTPS media if app is NOT coming from HTTPS
// 2) to URI in the current directory of the fusion cache
// 3) to site of origin media
if (SecurityHelper.AreStringTypesEqual(uriToOpen.Scheme, Uri.UriSchemeHttps))
{
// target is HTTPS. Then, elevate ONLY if we are NOT coming from HTTPS (=XDomain HTTPS app to HTTPS media disallowed)
Uri appDeploymentUri = SecurityHelper.ExtractUriForClickOnceDeployedApp();
if (!SecurityHelper.AreStringTypesEqual(appDeploymentUri.Scheme, Uri.UriSchemeHttps))
{
new WebPermission(NetworkAccess.Connect, BindUriHelper.UriToString(uriToOpen)).Assert();
elevated = true;
}
}
else
{
// elevate to allow access to media in the app's directory in the fusion cache.
new FileIOPermission(FileIOPermissionAccess.Read, appBase.LocalPath).Assert();// BlessedAssert
elevated = true;
}
// demand permissions. if demands succeds, it means we are in one of the cases above.
try
{
toOpen = DemandPermissions(uriToOpen);
}
finally
{
if (elevated)
{
CodeAccessPermission.RevertAssert();
}
}
}
else
{
toOpen = null;
}
// We pass in exact same URI for which we demanded permissions so that we can be sure
// there is no discrepancy between the two.
HRESULT.Check(MILMedia.Open(_nativeMedia, toOpen));
}
