ipv4: IP_ADD_MEMBERSHIP twice should return EADDRINUSE

also IP_ADD_SOURCE_MEMBERSHIP

Change-Id: Icc9af4fc7ffe6457ca968fad3fba46f0942a9e3f
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3418
Reviewed-by: Rene Gollent <[email protected]>

src/add-ons/kernel/network/protocols/ipv4/multicast.cpp

@@ -195,7 +195,8 @@ MulticastFilter<Addressing>::GetState(const AddressType &groupAddress,
 			return status;
 		}
 
-	}
+	} else if (create)
+		return EADDRINUSE;
 
 	return B_OK;
 }