PassiveCallbackHandler.java :  » J2EE » fleXive » com » flexive » core » security » Java Open Source

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package com.flexive.core.security;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import javax.ejb.SessionContext;
import javax.security.auth.callback.*;
import javax.sql.DataSource;
import java.io.IOException;


/**
 * PassiveCallbackHandler has constructor that takes
 * a username and password so its handle() method does
 * not have to prompt the user for input.
 * Useful for server-side applications.
 *
 * @author Gregor Schober (gregor.schober@flexive.com), UCS - unique computing solutions gmbh (http://www.ucs.at)
 */
public class PassiveCallbackHandler implements CallbackHandler {

    private static final transient Log LOG = LogFactory.getLog(PassiveCallbackHandler.class);
    private String username = null;
    private char[] password = null;
    private boolean takeOverSession = false;
    private SessionContext ctx = null;
    private DataSource ds = null;

    /**
     * Creates a callback handler with the give username and password.
     *
     * @param user            the username
     * @param pass            the password
     * @param takeOverSession if an existing session should be "taken over"
     * @param ctx             the session context to be used
     * @param ds              the datasource to be used for authentication
     */
    public PassiveCallbackHandler(String user, String pass, boolean takeOverSession,
                                  SessionContext ctx, DataSource ds) {
        if (user == null) user = "";
        if (pass == null) pass = "";
        this.username = user;
        this.password = pass.toCharArray();
        this.takeOverSession = takeOverSession;
        this.ctx = ctx;
        this.ds = ds;
    }

    /**
     * Handles the specified set of Callbacks. Uses the username and password that were supplied to our
     * constructor to popluate the Callbacks.
     * <p/>
     * This class supports NameCallback and PasswordCallback.
     *
     * @param callbacks the callbacks to handle
     * @throws IOException                  if an input or output error occurs.
     * @throws UnsupportedCallbackException if the callback is not an instance of NameCallback or PasswordCallback
     */
    public void handle(Callback[] callbacks) throws IOException, UnsupportedCallbackException {

        for (Callback callback : callbacks) {
            if (callback == null) continue;
            if (callback instanceof NameCallback) {
                ((NameCallback) callback).setName(username);
            } else if (callback instanceof PasswordCallback) {
                ((PasswordCallback) callback).setPassword(password);
            } else if (callback instanceof FxCallback) {
                FxCallback ac = ((FxCallback) callback);
                ac.setTakeOverSession(takeOverSession);
                ac.setDataSource(ds);
                ac.setSessionContext(ctx);
            } else {
                UnsupportedCallbackException uce = new UnsupportedCallbackException(callback, "Callback class ["
                        + callback.getClass() + "] not supported");
                LOG.error(uce);
                throw uce;
            }
        }

    }

    /**
     * Clears out password state.
     */
    public void clearPassword() {
        if (password != null) {
            for (int i = 0; i < password.length; i++)
                password[i] = ' ';
            password = null;
        }
    }

}