/*
 * @(#)SampleLoginModule.java	1.18 00/01/11
 *
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 * without modification, are permitted provided that the following 
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 * 
 * -Redistribution in binary form must reproduct the above copyright 
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 * the documentation and/or other materials provided with the 
 * distribution.
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 * from this software without specific prior written permission.
 * 
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package sample.module;

import java.util.*;
import java.io.IOException;
import javax.security.auth.*;
import javax.security.auth.callback.*;
import javax.security.auth.login.*;
import javax.security.auth.spi.*;
import sample.principal.SamplePrincipal;

/**
 * <p> This sample LoginModule authenticates users with a password.
 * 
 * <p> This LoginModule only recognizes one user:	testUser
 * <p> testUser's password is:	testPassword
 *
 * <p> If testUser successfully authenticates itself,
 * a <code>SamplePrincipal</code> with the testUser's user name
 * is added to the Subject.
 *
 * <p> This LoginModule recognizes the debug option.
 * If set to true in the login Configuration,
 * debug messages will be output to the output stream, System.out.
 *
 * @version 1.18, 01/11/00
 */
public class SampleLoginModule implements LoginModule {

    // initial state
    private Subject subject;
    private CallbackHandler callbackHandler;
    private Map sharedState;
    private Map options;

    // configurable option
    private boolean debug = false;

    // the authentication status
    private boolean succeeded = false;
    private boolean commitSucceeded = false;

    // username and password
    private String username;
    private char[] password;

    // testUser's SamplePrincipal
    private SamplePrincipal userPrincipal;

    /**
     * Initialize this <code>LoginModule</code>.
     *
     * <p>
     *
     * @param subject the <code>Subject</code> to be authenticated. <p>
     *
     * @param callbackHandler a <code>CallbackHandler</code> for communicating
     *			with the end user (prompting for user names and
     *			passwords, for example). <p>
     *
     * @param sharedState shared <code>LoginModule</code> state. <p>
     *
     * @param options options specified in the login
     *			<code>Configuration</code> for this particular
     *			<code>LoginModule</code>.
     */
    public void initialize(Subject subject, 
	           CallbackHandler callbackHandler,
			 Map<java.lang.String, ?> sharedState, 
			 Map<java.lang.String, ?> options) {
 
	this.subject = subject;
	this.callbackHandler = callbackHandler;
	this.sharedState = sharedState;
	this.options = options;

	// initialize any configured options
	debug = "true".equalsIgnoreCase((String)options.get("debug"));
    }

    /**
     * Authenticate the user by prompting for a user name and password.
     *
     * <p>
     *
     * @return true in all cases since this <code>LoginModule</code>
     *		should not be ignored.
     *
     * @exception FailedLoginException if the authentication fails. <p>
     *
     * @exception LoginException if this <code>LoginModule</code>
     *		is unable to perform the authentication.
     */
    public boolean login() throws LoginException {

	// prompt for a user name and password
	if (callbackHandler == null)
	    throw new LoginException("Error: no CallbackHandler available " +
			"to garner authentication information from the user");

	Callback[] callbacks = new Callback[2];
	callbacks[0] = new NameCallback("user name: ");
	callbacks[1] = new PasswordCallback("password: ", false);
 
	try {
	    callbackHandler.handle(callbacks);
	    username = ((NameCallback)callbacks[0]).getName();
	    char[] tmpPassword = ((PasswordCallback)callbacks[1]).getPassword();
	    if (tmpPassword == null) {
		// treat a NULL password as an empty password
		tmpPassword = new char[0];
	    }
	    password = new char[tmpPassword.length];
	    System.arraycopy(tmpPassword, 0,
			password, 0, tmpPassword.length);
	    ((PasswordCallback)callbacks[1]).clearPassword();
 
	} catch (java.io.IOException ioe) {
	    throw new LoginException(ioe.toString());
	} catch (UnsupportedCallbackException uce) {
	    throw new LoginException("Error: " + uce.getCallback().toString() +
		" not available to garner authentication information " +
		"from the user");
	}

	// print debugging information
	if (debug) {
	    System.out.println("\t\t[SampleLoginModule] " +
				"user entered user name: " +
				username);
	    System.out.print("\t\t[SampleLoginModule] " +
				"user entered password: ");
	    for (int i = 0; i < password.length; i++)
		System.out.print(password[i]);
	    System.out.println();
	}

	// verify the username/password
	boolean usernameCorrect = false;
	boolean passwordCorrect = false;
	if (username.equals("testUser"))
	    usernameCorrect = true;
	if (usernameCorrect &&
	    password.length == 12 &&
	    password[0] == 't' &&
	    password[1] == 'e' &&
	    password[2] == 's' &&
	    password[3] == 't' &&
	    password[4] == 'P' &&
	    password[5] == 'a' &&
	    password[6] == 's' &&
	    password[7] == 's' &&
	    password[8] == 'w' &&
	    password[9] == 'o' &&
	    password[10] == 'r' &&
	    password[11] == 'd') {

	    // authentication succeeded!!!
	    passwordCorrect = true;
	    if (debug)
		System.out.println("\t\t[SampleLoginModule] " +
				"authentication succeeded");
	    succeeded = true;
	    return true;
	} else {

	    // authentication failed -- clean out state
	    if (debug)
		System.out.println("\t\t[SampleLoginModule] " +
				"authentication failed");
	    succeeded = false;
	    username = null;
	    for (int i = 0; i < password.length; i++)
		password[i] = ' ';
	    password = null;
	    if (!usernameCorrect) {
		throw new FailedLoginException("User Name Incorrect");
	    } else {
		throw new FailedLoginException("Password Incorrect");
	    }
	}
    }

    /**
     * <p> This method is called if the LoginContext's
     * overall authentication succeeded
     * (the relevant REQUIRED, REQUISITE, SUFFICIENT and OPTIONAL LoginModules
     * succeeded).
     *
     * <p> If this LoginModule's own authentication attempt
     * succeeded (checked by retrieving the private state saved by the
     * <code>login</code> method), then this method associates a
     * <code>SamplePrincipal</code>
     * with the <code>Subject</code> located in the
     * <code>LoginModule</code>.  If this LoginModule's own
     * authentication attempted failed, then this method removes
     * any state that was originally saved.
     *
     * <p>
     *
     * @exception LoginException if the commit fails.
     *
     * @return true if this LoginModule's own login and commit
     *		attempts succeeded, or false otherwise.
     */
    public boolean commit() throws LoginException {
	if (succeeded == false) {
	    return false;
	} else {
	    // add a Principal (authenticated identity)
	    // to the Subject

	    // assume the user we authenticated is the SamplePrincipal
	    userPrincipal = new SamplePrincipal(username);
	    if (!subject.getPrincipals().contains(userPrincipal))
		subject.getPrincipals().add(userPrincipal);

	    if (debug) {
		System.out.println("\t\t[SampleLoginModule] " +
				"added SamplePrincipal to Subject");
	    }

	    // in any case, clean out state
	    username = null;
	    for (int i = 0; i < password.length; i++)
		password[i] = ' ';
	    password = null;

	    commitSucceeded = true;
	    return true;
	}
    }

    /**
     * <p> This method is called if the LoginContext's
     * overall authentication failed.
     * (the relevant REQUIRED, REQUISITE, SUFFICIENT and OPTIONAL LoginModules
     * did not succeed).
     *
     * <p> If this LoginModule's own authentication attempt
     * succeeded (checked by retrieving the private state saved by the
     * <code>login</code> and <code>commit</code> methods),
     * then this method cleans up any state that was originally saved.
     *
     * <p>
     *
     * @exception LoginException if the abort fails.
     *
     * @return false if this LoginModule's own login and/or commit attempts
     *		failed, and true otherwise.
     */
    public boolean abort() throws LoginException {
	if (succeeded == false) {
	    return false;
	} else if (succeeded == true && commitSucceeded == false) {
	    // login succeeded but overall authentication failed
	    succeeded = false;
	    username = null;
	    if (password != null) {
		for (int i = 0; i < password.length; i++)
		    password[i] = ' ';
		password = null;
	    }
	    userPrincipal = null;
	} else {
	    // overall authentication succeeded and commit succeeded,
	    // but someone else's commit failed
	    logout();
	}
	return true;
    }

    /**
     * Logout the user.
     *
     * <p> This method removes the <code>SamplePrincipal</code>
     * that was added by the <code>commit</code> method.
     *
     * <p>
     *
     * @exception LoginException if the logout fails.
     *
     * @return true in all cases since this <code>LoginModule</code>
     *          should not be ignored.
     */
    public boolean logout() throws LoginException {

	subject.getPrincipals().remove(userPrincipal);
	succeeded = false;
	succeeded = commitSucceeded;
	username = null;
	if (password != null) {
	    for (int i = 0; i < password.length; i++)
		password[i] = ' ';
	    password = null;
	}
	userPrincipal = null;
	return true;
    }
}