/**
* Handles all events related to messenger features: TextEvent, DrawEvent, ImageEvent,
* ClearWhiteBoardEvent, MouseButtonEvent
*
* <p>If an event direction is DOWN an hash is generated otherwise received and calculated hashes
* are compared. <br>
* Different hashes mean that an event is ignored
*
* @param ev
*/
private void handleInterestingEvent(GroupSendableEvent ev) {
Message message = ev.getMessage();
byte[] data;
Hash h = new Hash();
// String type;
if (ev.getDir() == Direction.DOWN) {
data = message.toByteArray();
md.update(data);
md.update(secret);
byte[] my = md.digest();
h.setHash(my);
message.pushObject(h);
md.reset();
// out.println("MD calculated");
ev.setObjectsMessage(message);
try {
ev.go();
} catch (AppiaEventException e) {
e.printStackTrace();
}
} else {
// incoming hash
h = (Hash) message.popObject();
data = message.toByteArray();
// calculates hash
md.update(data);
md.update(secret);
if (MessageDigest.isEqual(md.digest(), h.getHash())) {
// out.println("Valid");
try {
ev.go();
} catch (AppiaEventException e) {
e.printStackTrace();
}
}
// else{
// out.println("Error! Compromised message received!");
// out.println("Message ignored!");
// }
md.reset();
}
}
public void pushMySelf(Message m) {
m.pushObject(message);
m.pushInt(number);
}