/*
 * @(#)Configuration.java	1.63 06/04/21
 *
 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
 
package javax.security.auth.login;

import javax.security.auth.AuthPermission;
 
import java.io.*;
import java.util.*;
import java.net.URI;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.security.PrivilegedExceptionAction;
import java.security.PrivilegedActionException;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.Provider;
import java.security.Security;
import java.security.SecurityPermission;

import sun.security.jca.GetInstance;
 
/**
 * A Configuration object is responsible for specifying which LoginModules
 * should be used for a particular application, and in what order the
 * LoginModules should be invoked.
 *
 * <p> A login configuration contains the following information.
 * Note that this example only represents the default syntax for the
 * <code>Configuration</code>.  Subclass implementations of this class
 * may implement alternative syntaxes and may retrieve the
 * <code>Configuration</code> from any source such as files, databases,
 * or servers.
 *
 * <pre>
 *      Name {
 *	      ModuleClass  Flag    ModuleOptions;
 *	      ModuleClass  Flag    ModuleOptions;
 *	      ModuleClass  Flag    ModuleOptions;
 *      };
 *      Name {
 *	      ModuleClass  Flag    ModuleOptions;
 *	      ModuleClass  Flag    ModuleOptions;
 *      };
 *      other {
 *	      ModuleClass  Flag    ModuleOptions;
 *	      ModuleClass  Flag    ModuleOptions;
 *      };
 * </pre>
 *
 * <p> Each entry in the <code>Configuration</code> is indexed via an
 * application name, <i>Name</i>, and contains a list of
 * LoginModules configured for that application.  Each <code>LoginModule</code>
 * is specified via its fully qualified class name.
 * Authentication proceeds down the module list in the exact order specified.
 * If an application does not have specific entry,
 * it defaults to the specific entry for "<i>other</i>".
 *
 * <p> The <i>Flag</i> value controls the overall behavior as authentication
 * proceeds down the stack.  The following represents a description of the
 * valid values for <i>Flag</i> and their respective semantics:
 *
 * <pre>
 *      1) Required     - The <code>LoginModule</code> is required to succeed.
 *			If it succeeds or fails, authentication still continues
 *			to proceed down the <code>LoginModule</code> list.
 *
 *      2) Requisite    - The <code>LoginModule</code> is required to succeed.
 *			If it succeeds, authentication continues down the
 *			<code>LoginModule</code> list.  If it fails,
 *			control immediately returns to the application
 *			(authentication does not proceed down the
 *			<code>LoginModule</code> list).
 *
 *      3) Sufficient   - The <code>LoginModule</code> is not required to
 *			succeed.  If it does succeed, control immediately
 *			returns to the application (authentication does not
 *			proceed down the <code>LoginModule</code> list).
 *			If it fails, authentication continues down the
 *			<code>LoginModule</code> list.
 *
 *      4) Optional     - The <code>LoginModule</code> is not required to
 *			succeed.  If it succeeds or fails,
 *			authentication still continues to proceed down the
 *			<code>LoginModule</code> list.
 * </pre>
 *
 * <p> The overall authentication succeeds only if all <i>Required</i> and
 * <i>Requisite</i> LoginModules succeed.  If a <i>Sufficient</i>
 * <code>LoginModule</code> is configured and succeeds,
 * then only the <i>Required</i> and <i>Requisite</i> LoginModules prior to 
 * that <i>Sufficient</i> <code>LoginModule</code> need to have succeeded for
 * the overall authentication to succeed. If no <i>Required</i> or
 * <i>Requisite</i> LoginModules are configured for an application,
 * then at least one <i>Sufficient</i> or <i>Optional</i>
 * <code>LoginModule</code> must succeed.
 *
 * <p> <i>ModuleOptions</i> is a space separated list of
 * <code>LoginModule</code>-specific values which are passed directly to
 * the underlying LoginModules.  Options are defined by the
 * <code>LoginModule</code> itself, and control the behavior within it.
 * For example, a <code>LoginModule</code> may define options to support
 * debugging/testing capabilities.  The correct way to specify options in the
 * <code>Configuration</code> is by using the following key-value pairing:
 * <i>debug="true"</i>.  The key and value should be separated by an
 * 'equals' symbol, and the value should be surrounded by double quotes.
 * If a String in the form, MISSING_VALUE !, occurs in the value,
 * it will be expanded to the value of the system property.
 * Note that there is no limit to the number of
 * options a <code>LoginModule</code> may define.
 *
 * <p> The following represents an example <code>Configuration</code> entry
 * based on the syntax above:
 *
 * <pre>
 * Login {
 *   com.sun.security.auth.module.UnixLoginModule required;
 *   com.sun.security.auth.module.Krb5LoginModule optional
 *                   useTicketCache="true"
 *                   ticketCache="MISSING_VALUE !${/}tickets";
 * };
 * </pre>
 *
 * <p> This <code>Configuration</code> specifies that an application named,
 * "Login", requires users to first authenticate to the
 * <i>com.sun.security.auth.module.UnixLoginModule</i>, which is
 * required to succeed.  Even if the <i>UnixLoginModule</i>
 * authentication fails, the
 * <i>com.sun.security.auth.module.Krb5LoginModule</i>
 * still gets invoked.  This helps hide the source of failure.
 * Since the <i>Krb5LoginModule</i> is <i>Optional</i>, the overall
 * authentication succeeds only if the <i>UnixLoginModule</i>
 * (<i>Required</i>) succeeds.
 *
 * <p> Also note that the LoginModule-specific options,
 * <i>useTicketCache="true"</i> and
 * <i>ticketCache=MISSING_VALUE !${/}tickets"</i>,
 * are passed to the <i>Krb5LoginModule</i>.
 * These options instruct the <i>Krb5LoginModule</i> to
 * use the ticket cache at the specified location.
 * The system properties, <i>user.home</i> and <i>/</i>
 * (file.separator), are expanded to their respective values.
 *
 * <p> There is only one Configuration object installed in the runtime at any
 * given time.  A Configuration object can be installed by calling the
 * <code>setConfiguration</code> method.  The installed Configuration object
 * can be obtained by calling the <code>getConfiguration</code> method.
 *
 * <p> If no Configuration object has been installed in the runtime, a call to
 * <code>getConfiguration</code> installs an instance of the default
 * Configuration implementation (a default subclass implementation of this
 * abstract class).
 * The default Configuration implementation can be changed by setting the value
 * of the "login.configuration.provider" security property (in the Java
 * security properties file) to the fully qualified name of the desired
 * Configuration subclass implementation.  The Java security properties file
 * is located in the file named &lt;JAVA_HOME&gt;/lib/security/java.security.
 * &lt;JAVA_HOME&gt; refers to the value of the java.home system property,
 * and specifies the directory where the JRE is installed.
 *
 * <p> Application code can directly subclass Configuration to provide a custom
 * implementation.  In addition, an instance of a Configuration object can be
 * constructed by invoking one of the <code>getInstance</code> factory methods
 * with a standard type.  The default policy type is "JavaLoginConfig".
 * See Appendix A in the
 * <a href="../../../../../technotes/guides/security/crypto/CryptoSpec.html#AppA">
 * Java Cryptography Architecture API Specification &amp; Reference </a>
 * for a list of standard Configuration types.
 *
 * @version 1.63, 04/21/06
 * @see javax.security.auth.login.LoginContext
 */
public abstract class Configuration {

    private static Configuration configuration;
    private static ClassLoader contextClassLoader;

    static {
	contextClassLoader = (ClassLoader)AccessController.doPrivileged
		(new PrivilegedAction() {
		public Object run() {
		    return Thread.currentThread().getContextClassLoader();	
		}
	});
    };

    private static void checkPermission(String type) {
	SecurityManager sm = System.getSecurityManager();
	if (sm != null) {
	    sm.checkPermission(new AuthPermission
				("createLoginConfiguration." + type));
	}
    }

    /**
     * Sole constructor.  (For invocation by subclass constructors, typically
     * implicit.)
     */
    protected Configuration() { }

    /**
     * Get the installed login Configuration.
     *
     * <p>
     *
     * @return the login Configuration.  If a Configuration object was set
     *		via the <code>Configuration.setConfiguration</code> method,
     *		then that object is returned.  Otherwise, a default
     *		Configuration object is returned.
     *
     * @exception SecurityException if the caller does not have permission
     *				to retrieve the Configuration.
     *
     * @see #setConfiguration
     */
    public static synchronized Configuration getConfiguration() {

	SecurityManager sm = System.getSecurityManager();
	if (sm != null)
	    sm.checkPermission(new AuthPermission("getLoginConfiguration"));

	if (configuration == null) {
	    String config_class = null;
	    config_class = (String)AccessController.doPrivileged
		(new PrivilegedAction() {
		public Object run() {
		    return java.security.Security.getProperty
				("login.configuration.provider");
		}
	    });
	    if (config_class == null) {
		config_class = "com.sun.security.auth.login.ConfigFile";
	    }
 
	    try {
		final String finalClass = config_class;
		configuration = (Configuration)AccessController.doPrivileged
		    (new PrivilegedExceptionAction() {
		    public Object run() throws ClassNotFoundException,
					InstantiationException,
					IllegalAccessException {
			return Class.forName
				(finalClass,
				true,
				contextClassLoader).newInstance();
		    }
		});
	    } catch (PrivilegedActionException e) {
		Exception ee = e.getException();
		if (ee instanceof InstantiationException) {
		    throw (SecurityException) new
			SecurityException
				("Configuration error:" +
				 ee.getCause().getMessage() + 
				 "\n").initCause(ee.getCause());
		} else {
		    throw (SecurityException) new
			SecurityException
				("Configuration error: " +
				 ee.toString() + 
				 "\n").initCause(ee);
		}
	    }
	}
	return configuration;
    }
    
    /**
     * Set the login <code>Configuration</code>.
     *
     * <p>
     *
     * @param configuration the new <code>Configuration</code>
     *
     * @exception SecurityException if the current thread does not have
     *			Permission to set the <code>Configuration</code>.
     *
     * @see #getConfiguration
     */
    public static void setConfiguration(Configuration configuration) {
	SecurityManager sm = System.getSecurityManager();
	if (sm != null)
	    sm.checkPermission(new AuthPermission("setLoginConfiguration"));
	Configuration.configuration = configuration;
    }

    /**
     * Returns a Configuration object of the specified type.
     *
     * <p> This method traverses the list of registered security providers,
     * starting with the most preferred Provider.
     * A new Configuration object encapsulating the
     * ConfigurationSpi implementation from the first
     * Provider that supports the specified type is returned.
     *
     * <p> Note that the list of registered providers may be retrieved via
     * the {@link Security#getProviders() Security.getProviders()} method.
     *
     * @param type the specified Configuration type.  See Appendix A in the
     *    <a href="../../../../../technotes/guides/security/crypto/CryptoSpec.html#AppA">
     *    Java Cryptography Architecture API Specification &amp; Reference </a>
     *    for a list of standard Configuration types.
     *
     * @param params parameters for the Configuration, which may be null.
     *
     * @return the new Configuration object.
     *
     * @exception SecurityException if the caller does not have permission
     *		to get a Configuration instance for the specified type.
     *
     * @exception NullPointerException if the specified type is null.
     *
     * @exception IllegalArgumentException if the specified parameters
     *		are not understood by the ConfigurationSpi implementation
     *		from the selected Provider.
     *
     * @exception NoSuchAlgorithmException if no Provider supports a
     *		ConfigurationSpi implementation for the specified type.
     *
     * @see Provider
     * @since 1.6
     */
    public static Configuration getInstance(String type,
				Configuration.Parameters params)
                throws NoSuchAlgorithmException {

        checkPermission(type);
	try {
            GetInstance.Instance instance = GetInstance.getInstance
							("Configuration",
							ConfigurationSpi.class,
							type,
							params);
            return new ConfigDelegate((ConfigurationSpi)instance.impl,
							instance.provider,
							type,
							params);
	} catch (NoSuchAlgorithmException nsae) {
	    return handleException (nsae);
	}
    }

    /**
     * Returns a Configuration object of the specified type.
     *
     * <p> A new Configuration object encapsulating the
     * ConfigurationSpi implementation from the specified provider
     * is returned.   The specified provider must be registered
     * in the provider list.
     *
     * <p> Note that the list of registered providers may be retrieved via
     * the {@link Security#getProviders() Security.getProviders()} method.
     *
     * @param type the specified Configuration type.  See Appendix A in the
     *    <a href="../../../../../technotes/guides/security/crypto/CryptoSpec.html#AppA">
     *    Java Cryptography Architecture API Specification &amp; Reference </a>
     *    for a list of standard Configuration types.
     *
     * @param params parameters for the Configuration, which may be null.
     *
     * @param provider the provider.
     *
     * @return the new Configuration object.
     *
     * @exception SecurityException if the caller does not have permission
     *		to get a Configuration instance for the specified type.
     *
     * @exception NullPointerException if the specified type is null.
     *
     * @exception IllegalArgumentException if the specified provider
     *		is null or empty,
     *		or if the specified parameters are not understood by
     *		the ConfigurationSpi implementation from the specified provider.
     *
     * @exception NoSuchProviderException if the specified provider is not
     *		registered in the security provider list.
     *
     * @exception NoSuchAlgorithmException if the specified provider does not
     *		support a ConfigurationSpi implementation for the specified
     *		type.
     *
     * @see Provider
     * @since 1.6
     */
    public static Configuration getInstance(String type,
				Configuration.Parameters params,
				String provider)
		throws NoSuchProviderException, NoSuchAlgorithmException {

	if (provider == null || provider.length() == 0) {
	    throw new IllegalArgumentException("missing provider");
	}

	checkPermission(type);
	try {
	    GetInstance.Instance instance = GetInstance.getInstance
							("Configuration",
							ConfigurationSpi.class,
							type,
							params,
							provider);
	    return new ConfigDelegate((ConfigurationSpi)instance.impl,
							instance.provider,
							type,
							params);
	} catch (NoSuchAlgorithmException nsae) {
	    return handleException (nsae);
	}
    }

    /**
     * Returns a Configuration object of the specified type.
     *
     * <p> A new Configuration object encapsulating the
     * ConfigurationSpi implementation from the specified Provider
     * object is returned.  Note that the specified Provider object
     * does not have to be registered in the provider list.
     *
     * @param type the specified Configuration type.  See Appendix A in the
     *    <a href="../../../../../technotes/guides/security/crypto/CryptoSpec.html#AppA">
     *    Java Cryptography Architecture API Specification &amp; Reference </a>
     *    for a list of standard Configuration types.
     *
     * @param params parameters for the Configuration, which may be null.
     *
     * @param provider the Provider.
     *
     * @return the new Configuration object.
     *
     * @exception SecurityException if the caller does not have permission
     *		to get a Configuration instance for the specified type.
     *
     * @exception NullPointerException if the specified type is null.
     *
     * @exception IllegalArgumentException if the specified Provider is null,
     *		or if the specified parameters are not understood by
     *		the ConfigurationSpi implementation from the specified Provider.
     *
     * @exception NoSuchAlgorithmException if the specified Provider does not
     *		support a ConfigurationSpi implementation for the specified
     *		type.
     *
     * @see Provider
     * @since 1.6
     */
    public static Configuration getInstance(String type,
				Configuration.Parameters params,
				Provider provider)
		throws NoSuchAlgorithmException {

	if (provider == null) {
	    throw new IllegalArgumentException("missing provider");
	}

	checkPermission(type);
	try {
	    GetInstance.Instance instance = GetInstance.getInstance
							("Configuration",
							ConfigurationSpi.class,
							type,
							params,
							provider);
	    return new ConfigDelegate((ConfigurationSpi)instance.impl,
							instance.provider,
							type,
							params);
	} catch (NoSuchAlgorithmException nsae) {
	    return handleException (nsae);
	}
    }

    private static Configuration handleException(NoSuchAlgorithmException nsae)
		throws NoSuchAlgorithmException {
	Throwable cause = nsae.getCause();
	if (cause instanceof IllegalArgumentException) {
	    throw (IllegalArgumentException)cause;
	}
	throw nsae;
    }

    /**
     * Return the Provider of this Configuration.
     *
     * <p> This Configuration instance will only have a Provider if it
     * was obtained via a call to <code>Configuration.getInstance</code>.
     * Otherwise this method returns null.
     *
     * @return the Provider of this Configuration, or null.
     *
     * @since 1.6
     */
    public Provider getProvider() {
	return null;
    }

    /**
     * Return the type of this Configuration.
     *
     * <p> This Configuration instance will only have a type if it
     * was obtained via a call to <code>Configuration.getInstance</code>.
     * Otherwise this method returns null.
     *
     * @return the type of this Configuration, or null.
     *
     * @since 1.6
     */
    public String getType() {
	return null;
    }

    /**
     * Return Configuration parameters.
     *
     * <p> This Configuration instance will only have parameters if it
     * was obtained via a call to <code>Configuration.getInstance</code>.
     * Otherwise this method returns null.
     *
     * @return Configuration parameters, or null.
     *
     * @since 1.6
     */
    public Configuration.Parameters getParameters() {
	return null;
    }

    /**
     * Retrieve the AppConfigurationEntries for the specified <i>name</i>
     * from this Configuration.
     *
     * <p>
     *
     * @param name the name used to index the Configuration.
     * 
     * @return an array of AppConfigurationEntries for the specified <i>name</i>
     *		from this Configuration, or null if there are no entries
     *		for the specified <i>name</i>
     */
    public abstract AppConfigurationEntry[] getAppConfigurationEntry
							(String name);

    /**
     * Refresh and reload the Configuration.
     *
     * <p> This method causes this Configuration object to refresh/reload its
     * contents in an implementation-dependent manner.
     * For example, if this Configuration object stores its entries in a file,
     * calling <code>refresh</code> may cause the file to be re-read.
     *
     * <p> The default implementation of this method does nothing.
     * This method should be overridden if a refresh operation is supported
     * by the implementation.
     *
     * @exception SecurityException if the caller does not have permission
     *				to refresh its Configuration.
     */
    public void refresh() { }

    /**
     * This subclass is returned by the getInstance calls.  All Configuration
     * calls are delegated to the underlying ConfigurationSpi.
     */
    private static class ConfigDelegate extends Configuration {

        private ConfigurationSpi spi;
        private Provider p;
        private String type;
        private Configuration.Parameters params;

        private ConfigDelegate(ConfigurationSpi spi, Provider p,
                        String type, Configuration.Parameters params) {
            this.spi = spi;
            this.p = p;
            this.type = type;
            this.params = params;
        }

        public String getType() { return type; }

        public Configuration.Parameters getParameters() { return params; }

        public Provider getProvider() { return p; }

	public AppConfigurationEntry[] getAppConfigurationEntry(String name) {
            return spi.engineGetAppConfigurationEntry(name);
	}

        public void refresh() {
            spi.engineRefresh();
        }
    }

    /**
     * This represents a marker interface for Configuration parameters.
     *
     * @since 1.6
     */
    public static interface Parameters { }
}