/*
 * Copyright (c) 1998, 2022, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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 *
 */

package javax.security.auth.login;

import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.Map;
import java.util.HashMap;
import java.text.MessageFormat;
import javax.security.auth.Subject;
import javax.security.auth.AuthPermission;
import javax.security.auth.callback.*;
import javax.security.auth.spi.LoginModule;
import java.security.AccessControlContext;
import java.util.ServiceLoader;

import sun.security.util.PendingException;
import sun.security.util.ResourcesMgr;

import java.util.Set;
import java.util.WeakHashMap;
import java.util.stream.*;
import java.util.ServiceLoader.Provider;
/**
 * <p> The {@code LoginContext} class describes the basic methods used
 * to authenticate Subjects and provides a way to develop an
 * application independent of the underlying authentication technology.
 * A {@code Configuration} specifies the authentication technology, or
 * {@code LoginModule}, to be used with a particular application.
 * Different LoginModules can be plugged in under an application
 * without requiring any modifications to the application itself.
 *
 * <p> In addition to supporting <i>pluggable</i> authentication, this class
 * also supports the notion of <i>stacked</i> authentication.
 * Applications may be configured to use more than one
 * LoginModule.  For example, one could
 * configure both a Kerberos LoginModule and a smart card
 * LoginModule under an application.
 *
 * <p> A typical caller instantiates a LoginContext with
 * a <i>name</i> and a {@code CallbackHandler}.
 * LoginContext uses the <i>name</i> as the index into a
 * Configuration to determine which LoginModules should be used,
 * and which ones must succeed in order for the overall authentication to
 * succeed.  The {@code CallbackHandler} is passed to the underlying
 * LoginModules so they may communicate and interact with users
 * (prompting for a username and password via a graphical user interface,
 * for example).
 *
 * <p> Once the caller has instantiated a LoginContext,
 * it invokes the {@code login} method to authenticate
 * a {@code Subject}.  The {@code login} method invokes
 * the configured modules to perform their respective types of authentication
 * (username/password, smart card pin verification, etc.).
 * Note that the LoginModules will not attempt authentication retries nor
 * introduce delays if the authentication fails.
 * Such tasks belong to the LoginContext caller.
 *
 * <p> If the {@code login} method returns without
 * throwing an exception, then the overall authentication succeeded.
 * The caller can then retrieve
 * the newly authenticated Subject by invoking the
 * {@code getSubject} method.  Principals and Credentials associated
 * with the Subject may be retrieved by invoking the Subject's
 * respective {@code getPrincipals}, {@code getPublicCredentials},
 * and {@code getPrivateCredentials} methods.
 *
 * <p> To logout the Subject, the caller calls
 * the {@code logout} method.  As with the {@code login}
 * method, this {@code logout} method invokes the {@code logout}
 * method for the configured modules.
 *
 * <p> A LoginContext should not be used to authenticate
 * more than one Subject.  A separate LoginContext
 * should be used to authenticate each different Subject.
 *
 * <p> The following documentation applies to all LoginContext constructors:
 * <ol>
 *
 * <li> {@code Subject}
 * <ul>
 * <li> If the constructor has a Subject
 * input parameter, the LoginContext uses the caller-specified
 * Subject object.
 *
 * <li> If the caller specifies a {@code null} Subject
 * and a {@code null} value is permitted,
 * the LoginContext instantiates a new Subject.
 *
 * <li> If the constructor does <b>not</b> have a Subject
 * input parameter, the LoginContext instantiates a new Subject.
 * </ul>
 *
 * <li> {@code Configuration}
 * <ul>
 * <li> If the constructor has a Configuration
 * input parameter and the caller specifies a non-null Configuration,
 * the LoginContext uses the caller-specified Configuration.
 * <p>
 * If the constructor does <b>not</b> have a Configuration
 * input parameter, or if the caller specifies a {@code null}
 * Configuration object, the constructor uses the following call to
 * get the installed Configuration:
 * <pre>
 *      config = Configuration.getConfiguration();
 * </pre>
 * For both cases,
 * the <i>name</i> argument given to the constructor is passed to the
 * {@code Configuration.getAppConfigurationEntry} method.
 * If the Configuration has no entries for the specified <i>name</i>,
 * then the {@code LoginContext} calls
 * {@code getAppConfigurationEntry} with the name, "<i>other</i>"
 * (the default entry name).  If there is no entry for "<i>other</i>",
 * then a {@code LoginException} is thrown.
 *
 * <li> When LoginContext uses the installed Configuration, the caller
 * requires the createLoginContext.<em>name</em> and possibly
 * createLoginContext.other AuthPermissions. Furthermore, the
 * LoginContext will invoke configured modules from within an
 * {@code AccessController.doPrivileged} call so that modules that
 * perform security-sensitive tasks (such as connecting to remote hosts,
 * and updating the Subject) will require the respective permissions, but
 * the callers of the LoginContext will not require those permissions.
 *
 * <li> When LoginContext uses a caller-specified Configuration, the caller
 * does not require any createLoginContext AuthPermission.  The LoginContext
 * saves the {@code AccessControlContext} for the caller,
 * and invokes the configured modules from within an
 * {@code AccessController.doPrivileged} call constrained by that context.
 * This means the caller context (stored when the LoginContext was created)
 * must have sufficient permissions to perform any security-sensitive tasks
 * that the modules may perform.
 * </ul>
 *
 * <li> {@code CallbackHandler}
 * <ul>
 * <li> If the constructor has a CallbackHandler
 * input parameter, the LoginContext uses the caller-specified
 * CallbackHandler object.
 *
 * <li> If the constructor does <b>not</b> have a CallbackHandler
 * input parameter, or if the caller specifies a {@code null}
 * CallbackHandler object (and a {@code null} value is permitted),
 * the LoginContext queries the
 * {@code auth.login.defaultCallbackHandler} security property for the
 * fully qualified class name of a default handler
 * implementation. If the security property is not set,
 * then the underlying modules will not have a
 * CallbackHandler for use in communicating
 * with users.  The caller thus assumes that the configured
 * modules have alternative means for authenticating the user.
 *
 *
 * <li> When the LoginContext uses the installed Configuration (instead of
 * a caller-specified Configuration, see above),
 * then this LoginContext must wrap any
 * caller-specified or default CallbackHandler implementation
 * in a new CallbackHandler implementation
 * whose {@code handle} method implementation invokes the
 * specified CallbackHandler's {@code handle} method in a
 * {@code java.security.AccessController.doPrivileged} call
 * constrained by the caller's current {@code AccessControlContext}.
 * </ul>
 * </ol>
 *
 * @since 1.4
 * @see java.security.Security
 * @see javax.security.auth.AuthPermission
 * @see javax.security.auth.Subject
 * @see javax.security.auth.callback.CallbackHandler
 * @see javax.security.auth.login.Configuration
 * @see javax.security.auth.spi.LoginModule
 * @see java.security.Security security properties
 */
public class LoginContext {

    private static final String LOGIN_METHOD            = "login";
    private static final String COMMIT_METHOD           = "commit";
    private static final String ABORT_METHOD            = "abort";
    private static final String LOGOUT_METHOD           = "logout";
    private static final String OTHER                   = "other";
    private static final String DEFAULT_HANDLER         =
                                "auth.login.defaultCallbackHandler";
    private Subject subject = null;
    private boolean subjectProvided = false;
    private boolean loginSucceeded = false;
    private CallbackHandler callbackHandler;
    private final Map<String,?> state = new HashMap<>();

    private Configuration config;
    @SuppressWarnings("removal")
    private AccessControlContext creatorAcc = null;  // customized config only
    private ModuleInfo[] moduleStack;
    private ClassLoader contextClassLoader = null;

    // state saved in the event a user-specified asynchronous exception
    // was specified and thrown

    private int moduleIndex = 0;
    private LoginException firstError = null;
    private LoginException firstRequiredError = null;
    private boolean success = false;

    private static final sun.security.util.Debug debug =
        sun.security.util.Debug.getInstance("logincontext", "\t[LoginContext]");
    private static final WeakHashMap<ClassLoader, Set<Provider<LoginModule>>> providersCache =
        new WeakHashMap<>();

    @SuppressWarnings("removal")
    private void init(String name) throws LoginException {

        SecurityManager sm = System.getSecurityManager();
        if (sm != null && creatorAcc == null) {
            sm.checkPermission(new AuthPermission
                                ("createLoginContext." + name));
        }

        if (name == null)
            throw new LoginException
                (ResourcesMgr.getString("Invalid.null.input.name"));

        // get the Configuration
        if (config == null) {
            config = java.security.AccessController.doPrivileged
                (new java.security.PrivilegedAction<Configuration>() {
                public Configuration run() {
                    return Configuration.getConfiguration();
                }
            });
        }

        // get the LoginModules configured for this application
        AppConfigurationEntry[] entries = config.getAppConfigurationEntry(name);
        if (entries == null) {

            if (sm != null && creatorAcc == null) {
                sm.checkPermission(new AuthPermission
                                ("createLoginContext." + OTHER));
            }

            entries = config.getAppConfigurationEntry(OTHER);
            if (entries == null) {
                MessageFormat form = new MessageFormat(ResourcesMgr.getString
                        ("No.LoginModules.configured.for.name"));
                Object[] source = {name};
                throw new LoginException(form.format(source));
            }
        }
        moduleStack = new ModuleInfo[entries.length];
        for (int i = 0; i < entries.length; i++) {
            // clone returned array
            moduleStack[i] = new ModuleInfo
                                (new AppConfigurationEntry
                                        (entries[i].getLoginModuleName(),
                                        entries[i].getControlFlag(),
                                        entries[i].getOptions()),
                                null);
        }

        contextClassLoader = java.security.AccessController.doPrivileged
                (new java.security.PrivilegedAction<ClassLoader>() {
                public ClassLoader run() {
                    ClassLoader loader =
                            Thread.currentThread().getContextClassLoader();
                    if (loader == null) {
                        // Don't use bootstrap class loader directly to ensure
                        // proper package access control!
                        loader = ClassLoader.getSystemClassLoader();
                    }

                    return loader;
                }
        });

    }

    @SuppressWarnings("removal")
    private void loadDefaultCallbackHandler() throws LoginException {

        // get the default handler class
        try {

            final ClassLoader finalLoader = contextClassLoader;

            this.callbackHandler = java.security.AccessController.doPrivileged(
                new java.security.PrivilegedExceptionAction<CallbackHandler>() {
                public CallbackHandler run() throws Exception {
                    String defaultHandler = java.security.Security.getProperty
                        (DEFAULT_HANDLER);
                    if (defaultHandler == null || defaultHandler.isEmpty())
                        return null;
                    Class<? extends CallbackHandler> c = Class.forName(
                            defaultHandler, true,
                            finalLoader).asSubclass(CallbackHandler.class);
                    @SuppressWarnings("deprecation")
                    CallbackHandler result = c.newInstance();
                    return result;
                }
            });
        } catch (java.security.PrivilegedActionException pae) {
            throw new LoginException(pae.getException().toString());
        }

        // secure it with the caller's ACC
        if (this.callbackHandler != null && creatorAcc == null) {
            this.callbackHandler = new SecureCallbackHandler
                                (java.security.AccessController.getContext(),
                                this.callbackHandler);
        }
    }

    /**
     * Instantiate a new {@code LoginContext} object with a name.
     *
     * @param name the name used as the index into the
     *          {@code Configuration}.
     *
     * @exception LoginException if the caller-specified {@code name}
     *          does not appear in the {@code Configuration}
     *          and there is no {@code Configuration} entry
     *          for "{@code other}", or if the
     *          {@code auth.login.defaultCallbackHandler}
     *          security property was set, but the implementation
     *          class could not be loaded.
     *
     * @exception SecurityException if a SecurityManager is set and
     *          the caller does not have
     *          AuthPermission("createLoginContext.<i>name</i>"),
     *          or if a configuration entry for {@code name} does not exist and
     *          the caller does not additionally have
     *          AuthPermission("createLoginContext.other")
     */
    public LoginContext(String name) throws LoginException {
        init(name);
        loadDefaultCallbackHandler();
    }

    /**
     * Instantiate a new {@code LoginContext} object with a name
     * and a {@code Subject} object.
     *
     * @param name the name used as the index into the
     *          {@code Configuration}.
     *
     * @param subject the {@code Subject} to authenticate.
     *
     * @exception LoginException if the caller-specified {@code name}
     *          does not appear in the {@code Configuration}
     *          and there is no {@code Configuration} entry
     *          for "<i>other</i>", if the caller-specified {@code subject}
     *          is {@code null}, or if the
     *          <i>auth.login.defaultCallbackHandler</i>
     *          security property was set, but the implementation
     *          class could not be loaded.
     *
     * @exception SecurityException if a SecurityManager is set and
     *          the caller does not have
     *          AuthPermission("createLoginContext.<i>name</i>"),
     *          or if a configuration entry for <i>name</i> does not exist and
     *          the caller does not additionally have
     *          AuthPermission("createLoginContext.other")
     */
    public LoginContext(String name, Subject subject)
    throws LoginException {
        init(name);
        if (subject == null)
            throw new LoginException
                (ResourcesMgr.getString("invalid.null.Subject.provided"));
        this.subject = subject;
        subjectProvided = true;
        loadDefaultCallbackHandler();
    }

    /**
     * Instantiate a new {@code LoginContext} object with a name
     * and a {@code CallbackHandler} object.
     *
     * @param name the name used as the index into the
     *          {@code Configuration}.
     *
     * @param callbackHandler the {@code CallbackHandler} object used by
     *          LoginModules to communicate with the user.
     *
     * @exception LoginException if the caller-specified {@code name}
     *          does not appear in the {@code Configuration}
     *          and there is no {@code Configuration} entry
     *          for "{@code other}", or if the caller-specified
     *          {@code callbackHandler} is {@code null}.
     *
     * @exception SecurityException if a SecurityManager is set and
     *          the caller does not have
     *          AuthPermission("createLoginContext.<i>name</i>"),
     *          or if a configuration entry for <i>name</i> does not exist and
     *          the caller does not additionally have
     *          AuthPermission("createLoginContext.other")
     */
    @SuppressWarnings("removal")
    public LoginContext(String name, CallbackHandler callbackHandler)
    throws LoginException {
        init(name);
        if (callbackHandler == null)
            throw new LoginException(ResourcesMgr.getString
                                ("invalid.null.CallbackHandler.provided"));
        this.callbackHandler = new SecureCallbackHandler
                                (java.security.AccessController.getContext(),
                                callbackHandler);
    }

    /**
     * Instantiate a new {@code LoginContext} object with a name,
     * a {@code Subject} to be authenticated, and a
     * {@code CallbackHandler} object.
     *
     * @param name the name used as the index into the
     *          {@code Configuration}.
     *
     * @param subject the {@code Subject} to authenticate.
     *
     * @param callbackHandler the {@code CallbackHandler} object used by
     *          LoginModules to communicate with the user.
     *
     * @exception LoginException if the caller-specified {@code name}
     *          does not appear in the {@code Configuration}
     *          and there is no {@code Configuration} entry
     *          for "<i>other</i>", or if the caller-specified
     *          {@code subject} is {@code null},
     *          or if the caller-specified
     *          {@code callbackHandler} is {@code null}.
     *
     * @exception SecurityException if a SecurityManager is set and
     *          the caller does not have
     *          AuthPermission("createLoginContext.<i>name</i>"),
     *          or if a configuration entry for <i>name</i> does not exist and
     *          the caller does not additionally have
     *          AuthPermission("createLoginContext.other")
     */
    @SuppressWarnings("removal")
    public LoginContext(String name, Subject subject,
                        CallbackHandler callbackHandler) throws LoginException {
        this(name, subject);
        if (callbackHandler == null)
            throw new LoginException(ResourcesMgr.getString
                                ("invalid.null.CallbackHandler.provided"));
        this.callbackHandler = new SecureCallbackHandler
                                (java.security.AccessController.getContext(),
                                callbackHandler);
    }

    /**
     * Instantiate a new {@code LoginContext} object with a name,
     * a {@code Subject} to be authenticated,
     * a {@code CallbackHandler} object, and a login {@code Configuration}.
     *
     * @param name the name used as the index into the caller-specified
     *          {@code Configuration}.
     *
     * @param subject the {@code Subject} to authenticate,
     *          or {@code null}.
     *
     * @param callbackHandler the {@code CallbackHandler} object used by
     *          LoginModules to communicate with the user, or {@code null}.
     *
     * @param config the {@code Configuration} that lists the
     *          login modules to be called to perform the authentication,
     *          or {@code null}.
     *
     * @exception LoginException if the caller-specified {@code name}
     *          does not appear in the {@code Configuration}
     *          and there is no {@code Configuration} entry
     *          for "<i>other</i>".
     *
     * @exception SecurityException if a SecurityManager is set,
     *          <i>config</i> is {@code null},
     *          and either the caller does not have
     *          AuthPermission("createLoginContext.<i>name</i>"),
     *          or if a configuration entry for <i>name</i> does not exist and
     *          the caller does not additionally have
     *          AuthPermission("createLoginContext.other")
     *
     * @since 1.5
     */
    @SuppressWarnings("removal")
    public LoginContext(String name, Subject subject,
                        CallbackHandler callbackHandler,
                        Configuration config) throws LoginException {
        this.config = config;
        if (config != null) {
            creatorAcc = java.security.AccessController.getContext();
        }

        init(name);
        if (subject != null) {
            this.subject = subject;
            subjectProvided = true;
        }
        if (callbackHandler == null) {
            loadDefaultCallbackHandler();
        } else if (creatorAcc == null) {
            this.callbackHandler = new SecureCallbackHandler
                                (java.security.AccessController.getContext(),
                                callbackHandler);
        } else {
            this.callbackHandler = callbackHandler;
        }
    }

    /**
     * Perform the authentication.
     *
     * <p> This method invokes the {@code login} method for each
     * LoginModule configured for the <i>name</i> specified to the
     * {@code LoginContext} constructor, as determined by the login
     * {@code Configuration}.  Each {@code LoginModule}
     * then performs its respective type of authentication
     * (username/password, smart card pin verification, etc.).
     *
     * <p> This method completes a 2-phase authentication process by
     * calling each configured LoginModule's {@code commit} method
     * if the overall authentication succeeded (the relevant REQUIRED,
     * REQUISITE, SUFFICIENT, and OPTIONAL LoginModules succeeded),
     * or by calling each configured LoginModule's {@code abort} method
     * if the overall authentication failed.  If authentication succeeded,
     * each successful LoginModule's {@code commit} method associates
     * the relevant Principals and Credentials with the {@code Subject}.
     * If authentication failed, each LoginModule's {@code abort} method
     * removes/destroys any previously stored state.
     *
     * <p> If the {@code commit} phase of the authentication process
     * fails, then the overall authentication fails and this method
     * invokes the {@code abort} method for each configured
     * {@code LoginModule}.
     *
     * <p> If the {@code abort} phase
     * fails for any reason, then this method propagates the
     * original exception thrown either during the {@code login} phase
     * or the {@code commit} phase.  In either case, the overall
     * authentication fails.
     *
     * <p> In the case where multiple LoginModules fail,
     * this method propagates the exception raised by the first
     * {@code LoginModule} which failed.
     *
     * <p> Note that if this method enters the {@code abort} phase
     * (either the {@code login} or {@code commit} phase failed),
     * this method invokes all LoginModules configured for the
     * application regardless of their respective {@code Configuration}
     * flag parameters.  Essentially this means that {@code Requisite}
     * and {@code Sufficient} semantics are ignored during the
     * {@code abort} phase.  This guarantees that proper cleanup
     * and state restoration can take place.
     *
     * @exception LoginException if the authentication fails.
     */
    public void login() throws LoginException {

        loginSucceeded = false;

        if (subject == null) {
            subject = new Subject();
        }

        try {
            // module invoked in doPrivileged
            invokePriv(LOGIN_METHOD);
            invokePriv(COMMIT_METHOD);
            loginSucceeded = true;
        } catch (LoginException le) {
            try {
                invokePriv(ABORT_METHOD);
            } catch (LoginException le2) {
                throw le;
            }
            throw le;
        }
    }

    /**
     * Logout the {@code Subject}.
     *
     * <p> This method invokes the {@code logout} method for each
     * {@code LoginModule} configured for this {@code LoginContext}.
     * Each {@code LoginModule} performs its respective logout procedure
     * which may include removing/destroying
     * {@code Principal} and {@code Credential} information
     * from the {@code Subject} and state cleanup.
     *
     * <p> Note that this method invokes all LoginModules configured for the
     * application regardless of their respective
     * {@code Configuration} flag parameters.  Essentially this means
     * that {@code Requisite} and {@code Sufficient} semantics are
     * ignored for this method.  This guarantees that proper cleanup
     * and state restoration can take place.
     *
     * @exception LoginException if the logout fails.
     */
    public void logout() throws LoginException {
        if (subject == null) {
            throw new LoginException(ResourcesMgr.getString
                ("null.subject.logout.called.before.login"));
        }

        // module invoked in doPrivileged
        invokePriv(LOGOUT_METHOD);
    }

    /**
     * Return the authenticated Subject.
     *
     * @return the authenticated Subject.  If the caller specified a
     *          Subject to this LoginContext's constructor,
     *          this method returns the caller-specified Subject.
     *          If a Subject was not specified and authentication succeeds,
     *          this method returns the Subject instantiated and used for
     *          authentication by this LoginContext.
     *          If a Subject was not specified, and authentication fails or
     *          has not been attempted, this method returns null.
     */
    public Subject getSubject() {
        if (!loginSucceeded && !subjectProvided)
            return null;
        return subject;
    }

    private void clearState() {
        moduleIndex = 0;
        firstError = null;
        firstRequiredError = null;
        success = false;
    }

    private void throwException(LoginException originalError, LoginException le)
    throws LoginException {

        // first clear state
        clearState();

        // throw the exception
        throw (originalError != null) ? originalError : le;
    }

    /**
     * Invokes the login, commit, and logout methods
     * from a LoginModule inside a doPrivileged block restricted
     * by creatorAcc (may be null).
     *
     * This version is called if the caller did not instantiate
     * the LoginContext with a Configuration object.
     */
    @SuppressWarnings("removal")
    private void invokePriv(final String methodName) throws LoginException {
        try {
            java.security.AccessController.doPrivileged
                (new java.security.PrivilegedExceptionAction<Void>() {
                public Void run() throws LoginException {
                    invoke(methodName);
                    return null;
                }
            }, creatorAcc);
        } catch (java.security.PrivilegedActionException pae) {
            throw (LoginException)pae.getException();
        }
    }

    private void invoke(String methodName) throws LoginException {

        // start at moduleIndex
        // - this can only be non-zero if methodName is LOGIN_METHOD

        for (int i = moduleIndex; i < moduleStack.length; i++, moduleIndex++) {
            String name = moduleStack[i].entry.getLoginModuleName();
            try {

                if (moduleStack[i].module == null) {

                    // locate and instantiate the LoginModule
                    //
                    Set<Provider<LoginModule>> lmProviders;
                    synchronized(providersCache){
                        lmProviders = providersCache.get(contextClassLoader);
                        if (lmProviders == null){
                            if (debug != null){
                                debug.println("Build ServiceProviders cache for ClassLoader: " + contextClassLoader.getName());
                            }
                            @SuppressWarnings("removal")
                            ServiceLoader<LoginModule> sc = AccessController.doPrivileged(
                                    (PrivilegedAction<ServiceLoader<LoginModule>>)
                                            () -> java.util.ServiceLoader.load(
                                                LoginModule.class, contextClassLoader));
                            lmProviders = sc.stream().collect(Collectors.toSet());
                                if (debug != null){
                                    debug.println("Discovered ServiceProviders for ClassLoader: " + contextClassLoader.getName());
                                    lmProviders.forEach(System.err::println);
                                }
                            providersCache.put(contextClassLoader,lmProviders);
                        }
                    }
                    for (Provider<LoginModule> lm: lmProviders){
                        if (lm.type().getName().equals(name)){
                            moduleStack[i].module = lm.get();
                            if (debug != null) {
                                debug.println(name + " loaded as a service");
                            }
                            break;
                        }
                    }
                    if (moduleStack[i].module == null) {
                        try {
                            @SuppressWarnings("deprecation")
                            Object tmp = Class.forName(name, false, contextClassLoader).newInstance();
                            moduleStack[i].module = (LoginModule) tmp;
                            if (debug != null) {
                                debug.println(name + " loaded via reflection");
                            }
                        } catch (ClassNotFoundException e) {
                            throw new LoginException("No LoginModule found for "
                                    + name);
                        }
                    }

                    // invoke the LoginModule initialize method
                    moduleStack[i].module.initialize(subject,
                            callbackHandler,
                            state,
                            moduleStack[i].entry.getOptions());
                }

                // find the requested method in the LoginModule
                boolean status;
                switch (methodName) {
                    case LOGIN_METHOD:
                        status = moduleStack[i].module.login();
                        break;
                    case COMMIT_METHOD:
                        status = moduleStack[i].module.commit();
                        break;
                    case LOGOUT_METHOD:
                        status = moduleStack[i].module.logout();
                        break;
                    case ABORT_METHOD:
                        status = moduleStack[i].module.abort();
                        break;
                    default:
                        throw new AssertionError("Unknown method " + methodName);
                }

                if (status) {

                    // if SUFFICIENT, return if no prior REQUIRED errors
                    if (!methodName.equals(ABORT_METHOD) &&
                        !methodName.equals(LOGOUT_METHOD) &&
                        moduleStack[i].entry.getControlFlag() ==
                    AppConfigurationEntry.LoginModuleControlFlag.SUFFICIENT &&
                        firstRequiredError == null) {

                        // clear state
                        clearState();

                        if (debug != null)
                            debug.println(name + " " + methodName + " SUFFICIENT success");
                        return;
                    }

                    if (debug != null)
                        debug.println(name + " " + methodName + " success");
                    success = true;
                } else {
                    if (debug != null)
                        debug.println(name + " " + methodName + " ignored");
                }
            } catch (Exception ite) {

                // failure cases
                LoginException le;

                if (ite instanceof PendingException &&
                    methodName.equals(LOGIN_METHOD)) {

                    // XXX
                    //
                    // if a module's LOGIN_METHOD threw a PendingException
                    // then immediately throw it.
                    //
                    // when LoginContext is called again,
                    // the module that threw the exception is invoked first
                    // (the module list is not invoked from the start).
                    // previously thrown exception state is still present.
                    //
                    // it is assumed that the module which threw
                    // the exception can have its
                    // LOGIN_METHOD invoked twice in a row
                    // without any commit/abort in between.
                    //
                    // in all cases when LoginContext returns
                    // (either via natural return or by throwing an exception)
                    // we need to call clearState before returning.
                    // the only time that is not true is in this case -
                    // do not call throwException here.

                    throw (PendingException)ite;

                } else if (ite instanceof LoginException) {

                    le = (LoginException)ite;

                } else if (ite instanceof SecurityException) {

                    // do not want privacy leak
                    // (e.g., sensitive file path in exception msg)

                    le = new LoginException("Security Exception");
                    le.initCause(new SecurityException());
                    if (debug != null) {
                        debug.println
                            ("original security exception with detail msg " +
                            "replaced by new exception with empty detail msg");
                        debug.println("original security exception: " +
                                ite.toString());
                    }
                } else {

                    // capture an unexpected LoginModule exception
                    java.io.StringWriter sw = new java.io.StringWriter();
                    ite.printStackTrace
                            (new java.io.PrintWriter(sw));
                    sw.flush();
                    le = new LoginException(sw.toString());
                }

                if (moduleStack[i].entry.getControlFlag() ==
                    AppConfigurationEntry.LoginModuleControlFlag.REQUISITE) {

                    if (debug != null)
                        debug.println(name + " " + methodName + " REQUISITE failure");

                    // if REQUISITE, then immediately throw an exception
                    if (methodName.equals(ABORT_METHOD) ||
                        methodName.equals(LOGOUT_METHOD)) {
                        if (firstRequiredError == null)
                            firstRequiredError = le;
                    } else {
                        throwException(firstRequiredError, le);
                    }

                } else if (moduleStack[i].entry.getControlFlag() ==
                    AppConfigurationEntry.LoginModuleControlFlag.REQUIRED) {

                    if (debug != null)
                        debug.println(name + " " + methodName + " REQUIRED failure");

                    // mark down that a REQUIRED module failed
                    if (firstRequiredError == null)
                        firstRequiredError = le;

                } else {
                    if (debug != null) {
                        debug.println(name + " " + methodName + " OPTIONAL failure");
                        le.printStackTrace();
                    }

                    // mark down that an OPTIONAL module failed
                    if (firstError == null)
                        firstError = le;
                }
            }
        }

        // we went through all the LoginModules.
        if (firstRequiredError != null) {
            // a REQUIRED module failed -- return the error
            throwException(firstRequiredError, null);
        } else if (!success && firstError != null) {
            // no module succeeded -- return the first error
            throwException(firstError, null);
        } else if (!success) {
            // no module succeeded -- all modules were IGNORED
            throwException(new LoginException
                (ResourcesMgr.getString("Login.Failure.all.modules.ignored")),
                null);
        } else {
            // success

            clearState();
        }
    }

    /**
     * Wrap the caller-specified CallbackHandler in our own
     * and invoke it within a privileged block, constrained by
     * the caller's AccessControlContext.
     */
    private static class SecureCallbackHandler implements CallbackHandler {

        @SuppressWarnings("removal")
        private final java.security.AccessControlContext acc;
        private final CallbackHandler ch;

        SecureCallbackHandler(@SuppressWarnings("removal") java.security.AccessControlContext acc,
                        CallbackHandler ch) {
            this.acc = acc;
            this.ch = ch;
        }

        @SuppressWarnings("removal")
        public void handle(final Callback[] callbacks)
                throws java.io.IOException, UnsupportedCallbackException {
            try {
                java.security.AccessController.doPrivileged
                    (new java.security.PrivilegedExceptionAction<Void>() {
                    public Void run() throws java.io.IOException,
                                        UnsupportedCallbackException {
                        ch.handle(callbacks);
                        return null;
                    }
                }, acc);
            } catch (java.security.PrivilegedActionException pae) {
                if (pae.getException() instanceof java.io.IOException) {
                    throw (java.io.IOException)pae.getException();
                } else {
                    throw (UnsupportedCallbackException)pae.getException();
                }
            }
        }
    }

    /**
     * LoginModule information -
     *          encapsulates Configuration info and actual module instances
     */
    private static class ModuleInfo {
        AppConfigurationEntry entry;
        LoginModule module;

        ModuleInfo(AppConfigurationEntry newEntry, LoginModule newModule) {
            this.entry = newEntry;
            this.module = newModule;
        }
    }
}
