public boolean login()

in jaas/modules/src/main/java/org/apache/karaf/jaas/modules/properties/DigestPasswordLoginModule.java [118:234]
95 lines of code
22 McCabe index (conditional complexity)

    public boolean login() throws LoginException {
        if (usersFile == null) {
            throw new LoginException("The property users may not be null");
        }
        File f = new File(usersFile);
        if (!f.exists()) {
            throw new LoginException("Users file not found at " + f);
        }

        Properties users;
        try {
            users = new Properties(f);
        } catch (IOException ioe) {
            throw new LoginException("Unable to load user properties file " + f);
        }

        Callback[] callbacks = new Callback[2];

        callbacks[0] = new NameCallback("Username: ");
        callbacks[1] = new PasswordCallback("Password: ", false);
        if (callbackHandler != null) {
            try {
                callbackHandler.handle(callbacks);
            } catch (IOException ioe) {
                throw new LoginException(ioe.getMessage());
            } catch (UnsupportedCallbackException uce) {
                throw new LoginException(uce.getMessage() + " not available to obtain information from user");
            }
        }
        // user callback get value
        if (((NameCallback) callbacks[0]).getName() == null) {
            throw new LoginException("Username can not be null");
        }
        user = ((NameCallback) callbacks[0]).getName();
        if (user.startsWith(PropertiesBackingEngine.GROUP_PREFIX)) {
            // you can't log in under a group name
            throw new FailedLoginException("login failed");
        }

        // password callback get value
        if (((PasswordCallback) callbacks[1]).getPassword() == null) {
            throw new LoginException("Password can not be null");
        }
        String password = new String(((PasswordCallback) callbacks[1]).getPassword());

        // user infos container read from the users properties file
        String userInfos = null;
        try {
            userInfos = users.get(user);
        } catch (NullPointerException e) {
            //error handled in the next statement
        }
        if (userInfos == null) {
        	if (!this.detailedLoginExcepion) {
        		throw new FailedLoginException("login failed");
        	} else {
        		throw new FailedLoginException("User " + user + " does not exist");
        	}
        }

        // the password is in the first position
        String[] infos = userInfos.split(",");
        String storedPassword = infos[0];

        CallbackHandler myCallbackHandler = null;

        try {
            Field field = callbackHandler.getClass().getDeclaredField("ch");
            field.setAccessible(true);
            myCallbackHandler = (CallbackHandler) field.get(callbackHandler);
        } catch (Exception e) {
            throw new LoginException("Unable to load underlying callback handler");
        }

        if (myCallbackHandler instanceof NameDigestPasswordCallbackHandler) {
            NameDigestPasswordCallbackHandler digestCallbackHandler = (NameDigestPasswordCallbackHandler)myCallbackHandler;
            storedPassword = doPasswordDigest(digestCallbackHandler.getNonce(),
                                                            digestCallbackHandler.getCreatedTime(),
                                                            storedPassword);
        }

        // check the provided password
        if (!checkPassword(password, storedPassword)) {
        	if (!this.detailedLoginExcepion) {
        		throw new FailedLoginException("login failed");
        	} else {
        		throw new FailedLoginException("Password for " + user + " does not match");
        	}
        }

        principals = new HashSet<>();
        principals.add(new UserPrincipal(user));
        for (int i = 1; i < infos.length; i++) {
            if (infos[i].trim().startsWith(PropertiesBackingEngine.GROUP_PREFIX)) {
                // it's a group reference
                principals.add(new GroupPrincipal(infos[i].trim().substring(PropertiesBackingEngine.GROUP_PREFIX.length())));
                String groupInfo = users.get(infos[i].trim());
                if (groupInfo != null) {
                    String[] roles = groupInfo.split(",");
                    for (int j = 1; j < roles.length; j++) {
                        principals.add(new RolePrincipal(roles[j].trim()));
                    }
                }
            } else {
                // it's an user reference
                principals.add(new RolePrincipal(infos[i].trim()));
            }
        }

        users.clear();

        if (debug) {
            LOGGER.debug("Successfully logged in {}", user);
        }
        succeeded = true;
        return true;
    }