core: correctly handle pre-activation dependency failure (rh #1069695)

Dependencies may fail before the activation actually starts, like
when a software device gets removed while the activation is
scheduled but before it has started.  In these cases, the
activation request should fail.

src/nm-activation-request.c

@@ -308,18 +308,27 @@ device_state_changed (NMActiveConnection *active,
 	NMActiveConnectionState cur_ac_state = nm_active_connection_get_state (active);
 	NMActiveConnectionState ac_state = NM_ACTIVE_CONNECTION_STATE_UNKNOWN;
 
-	/* Ignore state changes when this activation request is not yet active, but
+	/* Decide which device state changes to handle when this active connection
-	 * handle the DISCONNECTED state correctly.  The device clears the
+	 * is not the device's current request.  Two cases here: (a) the AC is
-	 * activation request before sending the state change signal so this
+	 * pending and not yet active, and (b) the AC was active but the device is
-	 * must be special-cased to ensure the activation request is deactivated.
+	 * entering DISCONNECTED state (which clears the device's current AC before
+	 * emitting the state change signal).
 	 */
 	if (NM_ACTIVE_CONNECTION (nm_device_get_act_request (device)) != active) {
-		if (new_state != NM_DEVICE_STATE_DISCONNECTED)
+		/* Some other request is activating; this one must be pending */
-			return;
+		if (new_state >= NM_DEVICE_STATE_PREPARE)
-		if (cur_ac_state < NM_ACTIVE_CONNECTION_STATE_ACTIVATING)
 			return;
+		else if (new_state == NM_DEVICE_STATE_DISCONNECTED) {
+			/* This request hasn't started activating yet; the device is
+			 * disconnecting and cleaning up a previous activation request.
+			 */
+			if (cur_ac_state < NM_ACTIVE_CONNECTION_STATE_ACTIVATING)
+				return;
 
-		/* Catch device disconnections after this request has been active */
+			/* Catch device disconnections after this request has been active */
+		}
+
+		/* All states < DISCONNECTED are fatal and handled */
 	}
 
 	/* Set NMActiveConnection state based on the device's state */

src/nm-manager.c

@@ -2611,7 +2611,17 @@ _internal_activate_device (NMManager *self, NMActiveConnection *active, GError *
 
 	device = nm_active_connection_get_device (active);
 	if (!device) {
-		g_assert (connection_needs_virtual_device (connection));
+		if (!connection_needs_virtual_device (connection)) {
+			NMSettingConnection *s_con = nm_connection_get_setting_connection (connection);
+
+			g_assert (s_con);
+			g_set_error (error,
+			             NM_MANAGER_ERROR,
+			             NM_MANAGER_ERROR_UNKNOWN_DEVICE,
+			             "Unsupported virtual interface type '%s'",
+			             nm_setting_connection_get_connection_type (s_con));
+			return FALSE;
+		}
 
 		device = system_create_virtual_device (self, connection);
 		if (!device) {
@@ -2721,6 +2731,17 @@ _internal_activate_generic (NMManager *self, NMActiveConnection *active, GError
 	NMManagerPrivate *priv = NM_MANAGER_GET_PRIVATE (self);
 	gboolean success = FALSE;
 
+	/* Ensure activation request is still valid, eg that its device hasn't gone
+	 * away or that some other dependency has not failed.
+	 */
+	if (nm_active_connection_get_state (active) >= NM_ACTIVE_CONNECTION_STATE_DEACTIVATING) {
+		g_set_error_literal (error,
+		                     NM_MANAGER_ERROR,
+		                     NM_MANAGER_ERROR_DEPENDENCY_FAILED,
+		                     "Activation failed because dependencies failed.");
+		return FALSE;
+	}
+
 	if (NM_IS_VPN_CONNECTION (active))
 		success = _internal_activate_vpn (self, active, error);
 	else