public void BeforeNavigate2(object pDisp, ref object url, ref object flags, ref object targetFrameName, ref object postData, ref object headers, ref bool cancel)
{
bool newNavigationInitiated = false;
bool cancelRequested = false;
try
{
Debug.Assert(url == null || url is string, "invalid url type");
Debug.Assert(targetFrameName == null || targetFrameName is string, "invalid targetFrameName type");
Debug.Assert(headers == null || headers is string, "invalid headers type");
//
// Due to a
if (targetFrameName == null)
{
targetFrameName = "";
}
if (headers == null)
{
headers = "";
}
string urlString = (string)url;
Uri source = String.IsNullOrEmpty(urlString) ? null : new Uri(urlString);
UnsafeNativeMethods.IWebBrowser2 axIWebBrowser2 = (UnsafeNativeMethods.IWebBrowser2)pDisp;
// If _parent.AxIWebBrowser2 != axIWebBrowser2, navigation happens in a nested [i]frame.
// in that case we do not want to enforce site locking as we want the default IE behavior to take
// over.
if (_parent.AxIWebBrowser2 == axIWebBrowser2)
{
// The NavigatingToAboutBlank property indicates whether we are navigating to "about:blank"
// as a result of navigating to null or stream/string navigation.
// We set the NavigatingToAboutBlank bit to true in the WebBrowser DoNavigate method. When the above
// conditions occur, the NavigatingToAboutBlank is true and the source must be "about:blank".
//
// But when end user navigates away from the current about:blank page (by clicking
// on a hyperlink, Goback/Forward), or programmatically call GoBack and Forward,
// When we get the navigating event, NavigatingToAboutBlank is true, but the source is not "about:blank".
// Clear the NavigatingToAboutBlank bit in that case.
if ((_parent.NavigatingToAboutBlank) &&
String.Compare(urlString, WebBrowser.AboutBlankUriString, StringComparison.OrdinalIgnoreCase) != 0)
{
_parent.NavigatingToAboutBlank = false;
}
// Site locking for top level WebOC navigation
// "about:blank is not enabled in partial trust publicly.
// We enable it internally to navigate to null.
if ((!_parent.NavigatingToAboutBlank) &&
!SecurityHelper.CallerHasWebPermission(source) &&
!IsAllowedScriptScheme(source))
{
cancelRequested = true;
}
else
{
// When source set to null or navigating to stream/string, we navigate to "about:blank"
// internally. Make sure we pass null in the event args.
if (_parent.NavigatingToAboutBlank)
{
source = null;
}
NavigatingCancelEventArgs e = new NavigatingCancelEventArgs(source,
null, null, null, NavigationMode.New, null, null, true);
// TFS Dev10 520954 - Launching a navigation from the Navigating event handler causes reentrancy.
// For more info, see WebBrowser.LastNavigation. This is a point of possible reentrancy. Whenever
// a new navigation is started during the call to the Navigating event handler, we need to cancel
// out the current navigation.
Guid lastNavigation = _parent.LastNavigation;
// Fire navigating event. Events are only fired for top level navigation.
_parent.OnNavigating(e);
// TFS Dev10 520954 - Launching a navigation from the Navigating event handler causes reentrancy.
// For more info, see WebBrowser.LastNavigation. If _lastNavigation has changed during the call to
// the event handlers for Navigating, we know a new navigation has been initialized.
if (_parent.LastNavigation != lastNavigation)
{
newNavigationInitiated = true;
}
cancelRequested = e.Cancel;
}
}
}
// We disable this to suppress FXCop warning since in this case we really want to catch all exceptions
// please refer to comment below
#pragma warning disable 6502
catch
{
// This is an interesting pattern of putting a try catch block around this that catches everything,
// The reason I do this is based on a conversation with Microsoft. What happens here is if there is
// an exception in any of the code above then navigation still continues since COM interop eats up
// the exception. But what we want is for this navigation to fail.
// There fore I catch all exceptions and cancel navigation
cancelRequested = true;
}
#pragma warning restore 6502
finally
{
// Clean the WebBrowser control state if navigation cancelled.
//
// TFS Dev10 520954 - Launching a navigation from the Navigating event handler causes reentrancy.
// For more info, see WebBrowser.LastNavigation. A new navigation started during event handling for
// the Navigating event will have touched the control's global state. In case the navigation was
// cancelled in order to start a new navigation, we shouldn't tamper with that new state.
if (cancelRequested && !newNavigationInitiated)
{
_parent.CleanInternalState();
}
// TFS Dev10 520954 - Launching a navigation from the Navigating event handler causes reentrancy.
// For more info, see WebBrowser.LastNavigation. Whenever a new navigation is started during the
// call to the Navigating event handler, we need to cancel out the current navigation.
if (cancelRequested || newNavigationInitiated)
{
cancel = true;
}
}
}
