/*

 * Copyright 1995-2005 Sun Microsystems, Inc.  All Rights Reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Sun designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Sun in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package sun.applet;

import java.lang.NullPointerException;

import java.net.URL;

import java.net.URLClassLoader;

import java.net.SocketPermission;

import java.net.URLConnection;

import java.net.MalformedURLException;

import java.net.InetAddress;

import java.net.UnknownHostException;

import java.io.File;

import java.io.FilePermission;

import java.io.IOException;

import java.io.BufferedInputStream;

import java.io.InputStream;

import java.util.Enumeration;

import java.util.HashMap;

import java.util.NoSuchElementException;

import java.security.AccessController;

import java.security.AccessControlContext;

import java.security.PrivilegedAction;

import java.security.PrivilegedExceptionAction;

import java.security.PrivilegedActionException;

import java.security.CodeSource;

import java.security.Permission;

import java.security.PermissionCollection;

import sun.awt.AppContext;

import sun.awt.SunToolkit;

import sun.net.www.ParseUtil;

import sun.security.util.SecurityConstants;

/**

 * This class defines the class loader for loading applet classes and

 * resources. It extends URLClassLoader to search the applet code base

 * for the class or resource after checking any loaded JAR files.

 */

public class AppletClassLoader extends URLClassLoader {

    private URL base;   /* applet code base URL */

    private CodeSource codesource; /* codesource for the base URL */

    private AccessControlContext acc;

    private boolean exceptionStatus = false;

    private final Object threadGroupSynchronizer = new Object();

    private final Object grabReleaseSynchronizer = new Object();

    private boolean codebaseLookup = true;

    /*

     * Creates a new AppletClassLoader for the specified base URL.

     */

    protected AppletClassLoader(URL base) {

        super(new URL[0]);

        this.base = base;

        this.codesource =

            new CodeSource(base, (java.security.cert.Certificate[]) null);

        acc = AccessController.getContext();

    }

    /**

     * Set the codebase lookup flag.

     */

    void setCodebaseLookup(boolean codebaseLookup)  {

        this.codebaseLookup = codebaseLookup;

    }

    /*

     * Returns the applet code base URL.

     */

    URL getBaseURL() {

        return base;

    }

    /*

     * Returns the URLs used for loading classes and resources.

     */

    public URL[] getURLs() {

        URL[] jars = super.getURLs();

        URL[] urls = new URL[jars.length + 1];

        System.arraycopy(jars, 0, urls, 0, jars.length);

        urls[urls.length - 1] = base;

        return urls;

    }

    /*

     * Adds the specified JAR file to the search path of loaded JAR files.

     * Changed modifier to protected in order to be able to overwrite addJar()

     * in PluginClassLoader.java

     */

    protected void addJar(String name) throws IOException {

        URL url;

        try {

            url = new URL(base, name);

        } catch (MalformedURLException e) {

            throw new IllegalArgumentException("name");

        }

        addURL(url);

        // DEBUG

        //URL[] urls = getURLs();

        //for (int i = 0; i < urls.length; i++) {

        //    System.out.println("url[" + i + "] = " + urls[i]);

        //}

    }

    /*

     * Override loadClass so that class loading errors can be caught in

     * order to print better error messages.

     */

    public synchronized Class loadClass(String name, boolean resolve)

        throws ClassNotFoundException

    {

        // First check if we have permission to access the package. This

        // should go away once we've added support for exported packages.

        int i = name.lastIndexOf('.');

        if (i != -1) {

            SecurityManager sm = System.getSecurityManager();

            if (sm != null)

                sm.checkPackageAccess(name.substring(0, i));

        }

        try {

            return super.loadClass(name, resolve);

        } catch (ClassNotFoundException e) {

            //printError(name, e.getException());

            throw e;

        } catch (RuntimeException e) {

            //printError(name, e);

            throw e;

        } catch (Error e) {

            //printError(name, e);

            throw e;

        }

    }

    /*

     * Finds the applet class with the specified name. First searches

     * loaded JAR files then the applet code base for the class.

     */

    protected Class findClass(String name) throws ClassNotFoundException {

        int index = name.indexOf(";");

        String cookie = "";

        if(index != -1) {

                cookie = name.substring(index, name.length());

                name = name.substring(0, index);

        }

        // check loaded JAR files

        try {

            return super.findClass(name);

        } catch (ClassNotFoundException e) {

        }

        // Otherwise, try loading the class from the code base URL

        // 4668479: Option to turn off codebase lookup in AppletClassLoader

        // during resource requests. [stanley.ho]

        if (codebaseLookup == false)

            throw new ClassNotFoundException(name);

//      final String path = name.replace('.', '/').concat(".class").concat(cookie);

        String encodedName = ParseUtil.encodePath(name.replace('.', '/'), false);

        final String path = (new StringBuffer(encodedName)).append(".class").append(cookie).toString();

        try {

            byte[] b = (byte[]) AccessController.doPrivileged(

                               new PrivilegedExceptionAction() {

                public Object run() throws IOException {

                    return getBytes(new URL(base, path));

                }

            }, acc);

            if (b != null) {

                return defineClass(name, b, 0, b.length, codesource);

            } else {

                throw new ClassNotFoundException(name);

            }

        } catch (PrivilegedActionException e) {

            throw new ClassNotFoundException(name, e.getException());

        }

    }

    /**

     * Returns the permissions for the given codesource object.

     * The implementation of this method first calls super.getPermissions,

     * to get the permissions

     * granted by the super class, and then adds additional permissions

     * based on the URL of the codesource.

     * <p>

     * If the protocol is "file"

     * and the path specifies a file, permission is granted to read all files

     * and (recursively) all files and subdirectories contained in

     * that directory. This is so applets with a codebase of

     * file:/blah/some.jar can read in file:/blah/, which is needed to

     * be backward compatible. We also add permission to connect back to

     * the "localhost".

     *

     * @param codesource the codesource

     * @return the permissions granted to the codesource

     */

    protected PermissionCollection getPermissions(CodeSource codesource)

    {

        final PermissionCollection perms = super.getPermissions(codesource);

        URL url = codesource.getLocation();

        String path = null;

        Permission p;

        try {

            p = url.openConnection().getPermission();

        } catch (java.io.IOException ioe) {

            p = null;

        }

        if (p instanceof FilePermission) {

            path = p.getName();

        } else if ((p == null) && (url.getProtocol().equals("file"))) {

            path = url.getFile().replace('/', File.separatorChar);

            path = ParseUtil.decode(path);

        }

        if (path != null) {

            if (!path.endsWith(File.separator)) {

                int endIndex = path.lastIndexOf(File.separatorChar);

                if (endIndex != -1) {

                        path = path.substring(0, endIndex+1) + "-";

                        perms.add(new FilePermission(path,

                            SecurityConstants.FILE_READ_ACTION));

                }

            }

            perms.add(new SocketPermission("localhost",

                SecurityConstants.SOCKET_CONNECT_ACCEPT_ACTION));

            AccessController.doPrivileged(new PrivilegedAction() {

                public Object run() {

                    try {

                        String host = InetAddress.getLocalHost().getHostName();

                        perms.add(new SocketPermission(host,

                            SecurityConstants.SOCKET_CONNECT_ACCEPT_ACTION));

                    } catch (UnknownHostException uhe) {

                    }

                    return null;

                }

            });

            Permission bperm;

            try {

                bperm = base.openConnection().getPermission();

            } catch (java.io.IOException ioe) {

                bperm = null;

            }

            if (bperm instanceof FilePermission) {

                String bpath = bperm.getName();

                if (bpath.endsWith(File.separator)) {

                    bpath += "-";

                }

                perms.add(new FilePermission(bpath,

                    SecurityConstants.FILE_READ_ACTION));

            } else if ((bperm == null) && (base.getProtocol().equals("file"))) {

                String bpath = base.getFile().replace('/', File.separatorChar);

                bpath = ParseUtil.decode(bpath);

                if (bpath.endsWith(File.separator)) {

                    bpath += "-";

                }

                perms.add(new FilePermission(bpath, SecurityConstants.FILE_READ_ACTION));

            }

        }

        return perms;

    }

    /*

     * Returns the contents of the specified URL as an array of bytes.

     */

    private static byte[] getBytes(URL url) throws IOException {

        URLConnection uc = url.openConnection();

        if (uc instanceof java.net.HttpURLConnection) {

            java.net.HttpURLConnection huc = (java.net.HttpURLConnection) uc;

            int code = huc.getResponseCode();

            if (code >= java.net.HttpURLConnection.HTTP_BAD_REQUEST) {

                throw new IOException("open HTTP connection failed.");

            }

        }

        int len = uc.getContentLength();

        // Fixed #4507227: Slow performance to load

        // class and resources. [stanleyh]

        //

        // Use buffered input stream [stanleyh]

        InputStream in = new BufferedInputStream(uc.getInputStream());

        byte[] b;

        try {

            if (len != -1) {

                // Read exactly len bytes from the input stream

                b = new byte[len];

                while (len > 0) {

                    int n = in.read(b, b.length - len, len);

                    if (n == -1) {

                        throw new IOException("unexpected EOF");

                    }

                    len -= n;

                }

            } else {

                // Read until end of stream is reached - use 8K buffer

                // to speed up performance [stanleyh]

                b = new byte[8192];

                int total = 0;

                while ((len = in.read(b, total, b.length - total)) != -1) {

                    total += len;

                    if (total >= b.length) {

                        byte[] tmp = new byte[total * 2];

                        System.arraycopy(b, 0, tmp, 0, total);

                        b = tmp;

                    }

                }

                // Trim array to correct size, if necessary

                if (total != b.length) {

                    byte[] tmp = new byte[total];

                    System.arraycopy(b, 0, tmp, 0, total);

                    b = tmp;

                }

            }

        } finally {

            in.close();

        }

        return b;

    }

    // Object for synchronization around getResourceAsStream()

    private Object syncResourceAsStream = new Object();

    private Object syncResourceAsStreamFromJar = new Object();

    // Flag to indicate getResourceAsStream() is in call

    private boolean resourceAsStreamInCall = false;

    private boolean resourceAsStreamFromJarInCall = false;

    /**

     * Returns an input stream for reading the specified resource.

     *

     * The search order is described in the documentation for {@link

     * #getResource(String)}.<p>

     *

     * @param  name the resource name

     * @return an input stream for reading the resource, or <code>null</code>

     *         if the resource could not be found

     * @since  JDK1.1

     */

    public InputStream getResourceAsStream(String name)

    {

        if (name == null) {

            throw new NullPointerException("name");

        }

        try

        {

            InputStream is = null;

            // Fixed #4507227: Slow performance to load

            // class and resources. [stanleyh]

            //

            // The following is used to avoid calling

            // AppletClassLoader.findResource() in

            // super.getResourceAsStream(). Otherwise,

            // unnecessary connection will be made.

            //

            synchronized(syncResourceAsStream)

            {

                resourceAsStreamInCall = true;

                // Call super class

                is = super.getResourceAsStream(name);

                resourceAsStreamInCall = false;

            }

            // 4668479: Option to turn off codebase lookup in AppletClassLoader

            // during resource requests. [stanley.ho]

            if (codebaseLookup == true && is == null)

            {

                // If resource cannot be obtained,

                // try to download it from codebase

                URL url = new URL(base, ParseUtil.encodePath(name, false));

                is = url.openStream();

            }

            return is;

        }

        catch (Exception e)

        {

            return null;

        }

    }

    /**

     * Returns an input stream for reading the specified resource from the

     * the loaded jar files.

     *

     * The search order is described in the documentation for {@link

     * #getResource(String)}.<p>

     *

     * @param  name the resource name

     * @return an input stream for reading the resource, or <code>null</code>

     *         if the resource could not be found

     * @since  JDK1.1

     */

    public InputStream getResourceAsStreamFromJar(String name) {

        if (name == null) {

            throw new NullPointerException("name");

        }

        try {

            InputStream is = null;

            synchronized(syncResourceAsStreamFromJar) {

                resourceAsStreamFromJarInCall = true;

                // Call super class

                is = super.getResourceAsStream(name);

                resourceAsStreamFromJarInCall = false;

            }

            return is;

        } catch (Exception e) {

            return null;

        }

    }

    /*

     * Finds the applet resource with the specified name. First checks

     * loaded JAR files then the applet code base for the resource.

     */

    public URL findResource(String name) {

        // check loaded JAR files

        URL url = super.findResource(name);

        // 6215746:  Disable META-INF/* lookup from codebase in

        // applet/plugin classloader. [stanley.ho]

        if (name.startsWith("META-INF/"))

            return url;

        // 4668479: Option to turn off codebase lookup in AppletClassLoader

        // during resource requests. [stanley.ho]

        if (codebaseLookup == false)

            return url;

        if (url == null)

        {

            //#4805170, if it is a call from Applet.getImage()

            //we should check for the image only in the archives

            boolean insideGetResourceAsStreamFromJar = false;

                synchronized(syncResourceAsStreamFromJar) {

                insideGetResourceAsStreamFromJar = resourceAsStreamFromJarInCall;

            }

            if (insideGetResourceAsStreamFromJar) {

                return null;

            }

            // Fixed #4507227: Slow performance to load

            // class and resources. [stanleyh]

            //

            // Check if getResourceAsStream is called.

            //

            boolean insideGetResourceAsStream = false;

            synchronized(syncResourceAsStream)

            {

                insideGetResourceAsStream = resourceAsStreamInCall;

            }

            // If getResourceAsStream is called, don't

            // trigger the following code. Otherwise,

            // unnecessary connection will be made.

            //

            if (insideGetResourceAsStream == false)

            {

                // otherwise, try the code base

                try {

                    url = new URL(base, ParseUtil.encodePath(name, false));

                    // check if resource exists

                    if(!resourceExists(url))

                        url = null;

                } catch (Exception e) {

                    // all exceptions, including security exceptions, are caught

                    url = null;

                }

            }

        }

        return url;

    }

    private boolean resourceExists(URL url) {

        // Check if the resource exists.

        // It almost works to just try to do an openConnection() but

        // HttpURLConnection will return true on HTTP_BAD_REQUEST

        // when the requested name ends in ".html", ".htm", and ".txt"

        // and we want to be able to handle these

        //

        // Also, cannot just open a connection for things like FileURLConnection,

        // because they succeed when connecting to a nonexistent file.

        // So, in those cases we open and close an input stream.

        boolean ok = true;