/*

 * Copyright (c) 1996, 2013, Oracle and/or its affiliates. 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.  Oracle designates this

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

 * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package sun.rmi.transport.proxy;

import java.io.*;

import java.net.*;

import java.util.Hashtable;

/**

 * CGIClientException is thrown when an error is detected

 * in a client's request.

 */

class CGIClientException extends Exception {

    private static final long serialVersionUID = 8147981687059865216L;

    public CGIClientException(String s) {

        super(s);

    }

    public CGIClientException(String s, Throwable cause) {

        super(s, cause);

    }

}

/**

 * CGIServerException is thrown when an error occurs here on the server.

 */

class CGIServerException extends Exception {

    private static final long serialVersionUID = 6928425456704527017L;

    public CGIServerException(String s) {

        super(s);

    }

    public CGIServerException(String s, Throwable cause) {

        super(s, cause);

    }

}

/**

 * CGICommandHandler is the interface to an object that handles a

 * particular supported command.

 */

interface CGICommandHandler {

    /**

     * Return the string form of the command

     * to be recognized in the query string.

     */

    public String getName();

    /**

     * Execute the command with the given string as parameter.

     */

    public void execute(String param) throws CGIClientException, CGIServerException;

}

/**

 * The CGIHandler class contains methods for executing as a CGI program.

 * The main function interprets the query string as a command of the form

 * "{@code <command>=<parameters>}".

 *

 * This class depends on the CGI 1.0 environment variables being set as

 * properties of the same name in this Java VM.

 *

 * All data and methods of this class are static because they are specific

 * to this particular CGI process.

 */

public final class CGIHandler {

    /* get CGI parameters that we need */

    static int ContentLength;

    static String QueryString;

    static String RequestMethod;

    static String ServerName;

    static int ServerPort;

    static {

        java.security.AccessController.doPrivileged(

            new java.security.PrivilegedAction<Void>() {

            public Void run() {

                ContentLength =

                    Integer.getInteger("CONTENT_LENGTH", 0).intValue();

                QueryString = System.getProperty("QUERY_STRING", "");

                RequestMethod = System.getProperty("REQUEST_METHOD", "");

                ServerName = System.getProperty("SERVER_NAME", "");

                ServerPort = Integer.getInteger("SERVER_PORT", 0).intValue();

                return null;

            }

        });

    }

    /* list of handlers for supported commands */

    private static CGICommandHandler commands[] = {

        new CGIForwardCommand(),

        new CGIGethostnameCommand(),

        new CGIPingCommand(),

        new CGITryHostnameCommand()

    };

    /* construct table mapping command strings to handlers */

    private static Hashtable<String, CGICommandHandler> commandLookup;

    static {

        commandLookup = new Hashtable<>();

        for (int i = 0; i < commands.length; ++ i)

            commandLookup.put(commands[i].getName(), commands[i]);

    }

    /* prevent instantiation of this class */

    private CGIHandler() {}

    /**

     * Execute command given in query string on URL.  The string before

     * the first '=' is interpreted as the command name, and the string

     * after the first '=' is the parameters to the command.

     */

    public static void main(String args[])

    {

        try {

            String command, param;

            int delim = QueryString.indexOf('=');

            if (delim == -1) {

                command = QueryString;

                param = "";

            }

            else {

                command = QueryString.substring(0, delim);

                param = QueryString.substring(delim + 1);

            }

            CGICommandHandler handler =

                commandLookup.get(command);

            if (handler != null)

                try {

                    handler.execute(param);

                } catch (CGIClientException e) {

                    e.printStackTrace();

                    returnClientError(e.getMessage());

                } catch (CGIServerException e) {

                    e.printStackTrace();

                    returnServerError(e.getMessage());

                }

            else

                returnClientError("invalid command.");

        } catch (Exception e) {

            e.printStackTrace();

            returnServerError("internal error: " + e.getMessage());

        }

        System.exit(0);

    }

    /**

     * Return an HTML error message indicating there was error in

     * the client's request.

     */

    private static void returnClientError(String message)

    {

        System.out.println("Status: 400 Bad Request: " + message);

        System.out.println("Content-type: text/html");

        System.out.println("");

        System.out.println("<HTML>" +

                           "<HEAD><TITLE>Java RMI Client Error" +

                           "</TITLE></HEAD>" +

                           "<BODY>");

        System.out.println("<H1>Java RMI Client Error</H1>");

        System.out.println("");

        System.out.println(message);

        System.out.println("</BODY></HTML>");

        System.exit(1);

    }

    /**

     * Return an HTML error message indicating an error occurred

     * here on the server.

     */

    private static void returnServerError(String message)

    {

        System.out.println("Status: 500 Server Error: " + message);

        System.out.println("Content-type: text/html");

        System.out.println("");

        System.out.println("<HTML>" +

                           "<HEAD><TITLE>Java RMI Server Error" +

                           "</TITLE></HEAD>" +

                           "<BODY>");

        System.out.println("<H1>Java RMI Server Error</H1>");

        System.out.println("");

        System.out.println(message);

        System.out.println("</BODY></HTML>");

        System.exit(1);

    }

}

/**

 * "forward" command: Forward request body to local port on the server,

 * and send response back to client.

 */

final class CGIForwardCommand implements CGICommandHandler {

    public String getName() {

        return "forward";

    }

    @SuppressWarnings("deprecation")

    private String getLine (DataInputStream socketIn) throws IOException {

        return socketIn.readLine();

    }

    public void execute(String param) throws CGIClientException, CGIServerException

    {

        if (!CGIHandler.RequestMethod.equals("POST"))

            throw new CGIClientException("can only forward POST requests");

        int port;

        try {

            port = Integer.parseInt(param);

        } catch (NumberFormatException e) {

            throw new CGIClientException("invalid port number.", e);

        }

        if (port <= 0 || port > 0xFFFF)

            throw new CGIClientException("invalid port: " + port);

        if (port < 1024)

            throw new CGIClientException("permission denied for port: " +

                                         port);

        byte buffer[];

        Socket socket;

        try {

            socket = new Socket(InetAddress.getLocalHost(), port);

        } catch (IOException e) {

            throw new CGIServerException("could not connect to local port", e);

        }

        /*

         * read client's request body

         */

        DataInputStream clientIn = new DataInputStream(System.in);

        buffer = new byte[CGIHandler.ContentLength];

        try {

            clientIn.readFully(buffer);

        } catch (EOFException e) {

            throw new CGIClientException("unexpected EOF reading request body", e);

        } catch (IOException e) {

            throw new CGIClientException("error reading request body", e);

        }

        /*

         * send to local server in HTTP

         */

        try {

            DataOutputStream socketOut =

                new DataOutputStream(socket.getOutputStream());

            socketOut.writeBytes("POST / HTTP/1.0\r\n");

            socketOut.writeBytes("Content-length: " +

                                 CGIHandler.ContentLength + "\r\n\r\n");

            socketOut.write(buffer);

            socketOut.flush();

        } catch (IOException e) {

            throw new CGIServerException("error writing to server", e);

        }

        /*

         * read response

         */

        DataInputStream socketIn;

        try {

            socketIn = new DataInputStream(socket.getInputStream());

        } catch (IOException e) {

            throw new CGIServerException("error reading from server", e);

        }

        String key = "Content-length:".toLowerCase();

        boolean contentLengthFound = false;

        String line;

        int responseContentLength = -1;

        do {

            try {

                line = getLine(socketIn);

            } catch (IOException e) {

                throw new CGIServerException("error reading from server", e);

            }

            if (line == null)

                throw new CGIServerException(

                    "unexpected EOF reading server response");

            if (line.toLowerCase().startsWith(key)) {

                if (contentLengthFound) {

                    throw new CGIServerException(

                            "Multiple Content-length entries found.");

                } else {

                    responseContentLength =

                        Integer.parseInt(line.substring(key.length()).trim());

                    contentLengthFound = true;

                }

            }

        } while ((line.length() != 0) &&

                 (line.charAt(0) != '\r') && (line.charAt(0) != '\n'));

        if (!contentLengthFound || responseContentLength < 0)

            throw new CGIServerException(

                "missing or invalid content length in server response");

        buffer = new byte[responseContentLength];

        try {

            socketIn.readFully(buffer);

        } catch (EOFException e) {

            throw new CGIServerException(

                "unexpected EOF reading server response", e);

        } catch (IOException e) {

            throw new CGIServerException("error reading from server", e);

        }

        /*

         * send response back to client

         */

        System.out.println("Status: 200 OK");

        System.out.println("Content-type: application/octet-stream");

        System.out.println("");

        try {

            System.out.write(buffer);

        } catch (IOException e) {

            throw new CGIServerException("error writing response", e);

        }

        System.out.flush();

    }

}

/**

 * "gethostname" command: Return the host name of the server as the

 * response body

 */

final class CGIGethostnameCommand implements CGICommandHandler {

    public String getName() {

        return "gethostname";

    }

    public void execute(String param)

    {

        System.out.println("Status: 200 OK");

        System.out.println("Content-type: application/octet-stream");

        System.out.println("Content-length: " +

                           CGIHandler.ServerName.length());

        System.out.println("");

        System.out.print(CGIHandler.ServerName);

        System.out.flush();

    }

}

/**

 * "ping" command: Return an OK status to indicate that connection

 * was successful.

 */

final class CGIPingCommand implements CGICommandHandler {

    public String getName() {

        return "ping";

    }

    public void execute(String param)

    {

        System.out.println("Status: 200 OK");

        System.out.println("Content-type: application/octet-stream");

        System.out.println("Content-length: 0");

        System.out.println("");

    }

}

/**

 * "tryhostname" command: Return a human readable message describing

 * what host name is available to local Java VMs.

 */

final class CGITryHostnameCommand implements CGICommandHandler {

    public String getName() {

        return "tryhostname";

    }

    public void execute(String param)

    {

        System.out.println("Status: 200 OK");

        System.out.println("Content-type: text/html");

        System.out.println("");

        System.out.println("<HTML>" +

                           "<HEAD><TITLE>Java RMI Server Hostname Info" +

                           "</TITLE></HEAD>" +

                           "<BODY>");

        System.out.println("<H1>Java RMI Server Hostname Info</H1>");

        System.out.println("<H2>Local host name available to Java VM:</H2>");

        System.out.print("<P>InetAddress.getLocalHost().getHostName()");

        try {

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

            System.out.println(" = " + localHostName);

        } catch (UnknownHostException e) {

            System.out.println(" threw java.net.UnknownHostException");

        }

        System.out.println("<H2>Server host information obtained through CGI interface from HTTP server:</H2>");

        System.out.println("<P>SERVER_NAME = " + CGIHandler.ServerName);

        System.out.println("<P>SERVER_PORT = " + CGIHandler.ServerPort);

        System.out.println("</BODY></HTML>");

    }

}