android: Ignore IllegalArgumentException for multicast addresses

Some Android versions seem to reject routes that use multicast addresses.

Fixes #2420.

src/frontends/android/app/src/main/java/org/strongswan/android/logic/CharonVpnService.java

@@ -933,9 +933,20 @@ public class CharonVpnService extends VpnService implements Runnable, VpnStateSe
 					}
 					ranges.remove(mExcludedSubnets);
 					for (IPRange subnet : ranges.subnets())
+					{
+						try
 						{
 							builder.addRoute(subnet.getFrom(), subnet.getPrefix());
 						}
+						catch (IllegalArgumentException e)
+						{	/* some Android versions don't seem to like multicast addresses here,
+							 * ignore it for now */
+							if (!subnet.getFrom().isMulticastAddress())
+							{
+								throw e;
+							}
+						}
+					}
 				}
 				else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP)
 				{	/* allow traffic that would otherwise be blocked to bypass the VPN */
@@ -963,9 +974,19 @@ public class CharonVpnService extends VpnService implements Runnable, VpnStateSe
 					}
 					ranges.remove(mExcludedSubnets);
 					for (IPRange subnet : ranges.subnets())
+					{
+						try
 						{
 							builder.addRoute(subnet.getFrom(), subnet.getPrefix());
 						}
+						catch (IllegalArgumentException e)
+						{
+							if (!subnet.getFrom().isMulticastAddress())
+							{
+								throw e;
+							}
+						}
+					}
 				}
 				else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP)
 				{