client/src/main/java/envoy/client/ui/Startup.java

@@ -93,8 +93,9 @@ public final class Startup extends Application {
 			logger.info("Attempting authentication with token...");
 			localDB.initializeUserStorage();
 			localDB.loadUserData();
-			performHandshake(LoginCredentials.loginWithToken(localDB.getUser().getName(), localDB.getAuthToken(), VERSION, localDB.getLastSync()));
+			if (!performHandshake(
-			// TODO: handle unsuccessful handshake
+					LoginCredentials.loginWithToken(localDB.getUser().getName(), localDB.getAuthToken(), VERSION, localDB.getLastSync())))
+				sceneContext.load(SceneInfo.LOGIN_SCENE);
 		} else {
 
 			// Load login scene
@@ -106,9 +107,10 @@ public final class Startup extends Application {
 	 * Tries to perform a Handshake with the server.
 	 *
 	 * @param credentials the credentials to use for the handshake
+	 * @return whether the handshake was successful or offline mode could be entered
 	 * @since Envoy Client v0.2-beta
 	 */
-	public static void performHandshake(LoginCredentials credentials) {
+	public static boolean performHandshake(LoginCredentials credentials) {
 		final var cacheMap = new CacheMap();
 		cacheMap.put(Message.class, new Cache<Message>());
 		cacheMap.put(GroupMessage.class, new Cache<GroupMessage>());
@@ -120,10 +122,13 @@ public final class Startup extends Application {
 			if (client.isOnline()) {
 				loadChatScene();
 				client.initReceiver(localDB, cacheMap);
+				return true;
+			} else {
+				return false;
 			}
 		} catch (IOException | InterruptedException | TimeoutException e) {
 			logger.log(Level.INFO, "Could not connect to server. Entering offline mode...");
-			attemptOfflineMode(credentials.getIdentifier());
+			return attemptOfflineMode(credentials.getIdentifier());
 		}
 	}
 
@@ -132,9 +137,10 @@ public final class Startup extends Application {
 	 * for a given user.
 	 *
 	 * @param identifier the identifier of the user - currently his username
+	 * @return whether the offline mode could be entered
 	 * @since Envoy Client v0.2-beta
 	 */
-	public static void attemptOfflineMode(String identifier) {
+	public static boolean attemptOfflineMode(String identifier) {
 		try {
 			// Try entering offline mode
 			localDB.loadUsers();
@@ -142,10 +148,12 @@ public final class Startup extends Application {
 			if (clientUser == null) throw new EnvoyException("Could not enter offline mode: user name unknown");
 			client.setSender(clientUser);
 			loadChatScene();
+			return true;
 		} catch (final Exception e) {
 			new Alert(AlertType.ERROR, "Client error: " + e).showAndWait();
 			logger.log(Level.SEVERE, "Offline mode could not be loaded: ", e);
 			System.exit(1);
+			return false;
 		}
 	}
 

server/src/main/java/envoy/server/processors/LoginCredentialProcessor.java

@@ -122,10 +122,20 @@ public final class LoginCredentialProcessor implements ObjectProcessor<LoginCred
 		user.setStatus(ONLINE);
 		UserStatusChangeProcessor.updateUserStatus(user);
 
-		// Generate a new token if requested
+		// Process token request
 		if (credentials.requestToken()) {
-			String token = AuthTokenGenerator.nextToken();
+			String token;
+
+			if (user.getAuthToken() != null && user.getAuthTokenExpiration().isAfter(Instant.now())) {
+
+				// Reuse existing token and delay expiration date
+				token = user.getAuthToken();
+			} else {
+
+				// Generate new token
+				token = AuthTokenGenerator.nextToken();
 				user.setAuthToken(token);
+			}
 			user.setAuthTokenExpiration(Instant.now().plus(ServerConfig.getInstance().getAuthTokenExpiration().longValue(), ChronoUnit.DAYS));
 			persistenceManager.updateContact(user);
 			writeProxy.write(socketID, new NewAuthToken(token));