/*%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

	Copyright (c) Non, Inc. 1997 -- All Rights Reserved

PROJECT:	Servlet Library
MODULE:		Servlets
FILE:		PosterServlet.java

AUTHOR:		John D. Mitchell, Oct  5, 1997

REVISION HISTORY:
	Name	Date		Description
	----	----		-----------
	JDM	97.10.05   	Initial version.
	JDM	97.10.11	Added temp. directory clearing.

DESCRIPTION:

	This servlet helps to deal with the problem that applets can't do a
	showDocument() call on a POST request.  However, we can work around
	this by accepting the POST with the servlet, generating a temporary
	file containing the desired web page output, returning a magic
	string to the applet for encoding in the URL of a showDocument()
	call (which is a GET request), accepting the showDocument()'s
	request, decoding the magic string, and returning the previously
	generated content/file.

	Note that all of the calls to log() are commented out since JWS
	v1.1a seems to crash if log() is used inside of catch blocks.

INSTALLATION:

	Compile this code and put it into the 
	$JSERV_HOME/servlets/net/non/servlets/ directory.

	Add it to the known servlets list using the adminstration tool.

	Add a servlet alias for it of "/poster".


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%*/


package net.non.servlets;


// Standard Java core packages:

import	java.io.*;
import	java.util.*;


// Java Servlet packages:

import	javax.servlet.*;
import	javax.servlet.http.*;
import	javax.servlet.http.HttpUtils.*;


public class PosterServlet extends HttpServlet
    {
    // The file/path name parts for the temporary files.
    protected String posterTempDir = "posters";
    protected String posterTempExt = ".pst";

    // Default value for limit of GET & POST information that we'll accept
    // so as to protect ourselves from a DOS attack.
    protected int postContentLimit = 100*1024;		// 100KB limit.
    protected int getContentLimit = 1*1024;		// 1KB limit.

    // Random number generator (helps generate temporary filenames.
    protected Random randomizer = null;


    // Override getServletInfo().
    public String getServletInfo()
	{
	return ( "Copyright Non, Inc. 1997 -- " +
		 "John D. Mitchell (john@non.net)\n\n" +
		 "POST HTTP servlet." );
	}

    public void init (ServletConfig sc)
	{
	// Create the randomizer.
	randomizer = new Random ();

	// Delete all of the (abandoned) generated files.
	clearTempDir();
	}


    protected void doPost (HttpServletRequest request,
			   HttpServletResponse response)
	throws ServletException, IOException
	{
	// Process the incoming information, generate page output, generate
	// response output.


	// Set the response type.
	response.setContentType ("text/plain");

	// Check to limit Denial of Service attack.
	// Limit POST information to a reasonable size.
	if (postContentLimit < request.getContentLength())
	    {
	    sendPostFailure (response,
			     "Exceeded POST data length limit. Go away punk!");

/*	    // Log the error for the SysAdmin.
	    log ("PosterServlet:  POST content exceeded limit!");
*/
	    return;
	    }


	// Build the ouput filename.
	String fileName = (new Long (randomizer.nextLong())).toString();
	File file = null;
	try
	    {
	    file = new File (posterTempDir + File.separator +
			     fileName + posterTempExt);
	    }
	catch (Exception e)
	    {
	    // Sigh.  Something is really wrong since this is only supposed
	    // to throw up if the path doesn't exist.
	    sendPostFailure (response,
			     "Unable to build output file path!");

/*	    // Log the error for the SysAdmin.
	    log ("PosterServlet:  Not allowed to access :" +
		 file.getAbsolutePath() +
		 ":  Please check the permissions.");
*/
	    return;
	    }


	// Open the output file.
	PrintWriter output = null;
	try
	    {
	    output = new PrintWriter
		( new BufferedWriter
		  ( new FileWriter (file)));
	    }
	catch (IOException e)
	    {
	    // Hmm... Couldn't open the file.
	    sendPostFailure (response, "Unable to open output file!");

/*	    // Log the error for the SysAdmin.
	    log ("PosterServlet:  Unable to open :" +
		 file.getAbsolutePath() +
		 ": for writing. Please check the permissions.");
*/
	    return;
	    }

	// Spew out the appropriate header shme.
	output.println ("<html>");
	output.print ("<head><title>Poster Servlet Generated Output");
	output.println ("</title></head>");
	output.println ("<body>");


	// Now, loop through the request headers and spew them to the file.
	String headerName = null;
	Enumeration headers = request.getHeaderNames();
	if (headers.hasMoreElements())
	    {
	    output.println ("<h1>CGI headers:</h1><hr>");
	    output.println ("<ul>");
	    while (headers.hasMoreElements())
		{
		headerName = (String) headers.nextElement();
		output.print ("<li><b>");
		output.print (headerName);
		output.print (" = ");
		output.print (request.getHeader (headerName));
		output.println ("</b></li><br>");
		}
	    output.println ("</ul><hr><br>");
	    }

	// Deal with the POST contents.
	if (0 < request.getContentLength())
	    {
	    String line = null;

	    // Translate all of those incoming bytes to characters.
	    BufferedReader in = new BufferedReader
		( new InputStreamReader (request.getInputStream()));
	    
	    output.println ("<h1>POST contents:<h1><hr>");
	    output.println ("<p><pre>");


	    // Read each line of input and spew it to the output file.
	    HttpUtils httpUtils = new HttpUtils();
	    try
		{
		while (null != (line = in.readLine()))
		    {
		    try
			{
			Hashtable data = httpUtils.parseQueryString (line);

			// Rip through the list of entries and write out
			// each pair to a single line of the output file.
			String keyName = null;
			Enumeration keys = data.keys();

			// Should really also URLDecode the data but it's
			// not provided as part of the standard Java
			// classes and I don't want to add yet more code to
			// this example.
			while (keys.hasMoreElements())
			    {
			    String[] values = null;

			    keyName = (String) keys.nextElement();
			    output.print (keyName);

			    values = (String[]) data.get (keyName);

			    output.print (" =");
			    if (1 < values.length)
				output.println ("");
			    for (int i = 0; i < values.length; i++)
				{
				output.print ("\t");
				output.println (values[i]);
				}
			    }
			output.println();
			}
		    catch (IllegalArgumentException e)
			{
			// Couldn't seem to parse the query string.
			// Just dump the raw input string to the output.
			output.print (line);
			}
		    }
		}
	    catch (IOException e)
		{
		// Must have been some sort of input error.
		// Just note it and continue.
		output.println ("\n</pre><br><p><b>");
		output.println ("Unable to read entire POST contents!");
		output.println ("</b></p><br><pre>\n");
		}

	    output.println ("</pre></p><hr>");
	    }

	// Tidy up the output file.
	output.println ("</body></html>");
	output.flush();
	output.close();


	// Build the POST response.
	ServletOutputStream out = response.getOutputStream();
	out.println (fileName);
	out.println ("That is the magic value to return as a URL " +
		     "parameter in a showDocument() call to\n" +
		     "get the data generated by this POST call.");
	}	// End of doPost().


    protected void doGet (HttpServletRequest request,
			  HttpServletResponse response)
	throws ServletException, IOException
	{
	// Get magic information, get previously generated output page,
	// and then generate response.


	// Set the content type.
	response.setContentType ("text/html");

	// Check to limit Denial of Service attack.
	// Limit GET information to a reasonable size.
	if (getContentLimit < request.getContentLength())
	    {
	    sendGetFailure (response,
			    "Exceeded GET data length limit. Go away punk!");

/*	    // Log the error for the SysAdmin.
	    log ("PosterServlet:  GET content exceeded limit!");
*/
	    return;
	    }


	// Get the identifier the doPost() method gave the caller, if any.
	String fileName = request.getQueryString();
	if ((null == fileName) || fileName.equals (""))
	    {
	    // No file name.  Tell the caller to use the POST first.
	    sendGetFailure (response,
			    "Invalid or missing output file key!<br>"	+
			    "You must first POST to this servlet "	+
			    "to get generate a response file & key");
	    return;
	    }


	// Build the input filename.
	File file = null;
	try
	    {
	    file = new File (posterTempDir + File.separator +
			     fileName + posterTempExt);
	    }
	catch (Exception e)
	    {
	    // Sigh.  Something is really wrong since this is only supposed
	    // to throw up if the path doesn't exist.
	    sendGetFailure (response,
			    "Unable to get data file. Please start over!");

/*	    // Log the error for the SysAdmin.
	    log ("PosterServlet:  Not allowed to get input file :" +
		 file.getAbsolutePath() +
		 ":  Please check the permissions.");
*/
	    return;
	    }

	// Open the file.
	BufferedReader input = null;
	try
	    {
	    input = new BufferedReader ( new FileReader (file));
	    }
	catch (FileNotFoundException e)
	    {
	    // Non-existent file.  Bummer.
	    sendGetFailure (response,
			    "Unable to find data file. Please start over!");
	    return;
	    }


	// Read in the data file and spew it out.
	ServletOutputStream out = response.getOutputStream();
	String line = null;
	try
	    {
	    while (null != (line = input.readLine()))
		{
		out.println (line);
		}
	    }
	catch (IOException e)
	    {
	    // Must have been some sort of input error.
	    // Just note it and continue.
	    out.println ("\n<br><p><b>");
	    out.println ("Unable to read entire data file contents!");
	    out.println ("</b></p><br>\n");
	    }

	// Close and delete the input file.
	input.close();
	try 
	    {
	    if (!file.delete())
		{
/*		// Log the error for the SysAdmin to deal with.
		log ("PosterServlet: Unable to delete :" +
		     file.getAbsolutePath() + ":");
*/
		}
	    }
	catch (SecurityException e)
	    {
/*	    // Log the error for the SysAdmin to deal with.
	    log ("PosterServlet:  Not allowd to delete :" +
		 file.getAbsolutePath() +
		 ":  Please check the permissions.");
*/
	    }
	}	// End of doGet().


    private void sendPostFailure (HttpServletResponse response,
				  String reason)
	throws IOException
	{
	ServletOutputStream out = response.getOutputStream();

	out.println ("nil");
	out.println (reason);
	}	// End of sendPostFailure().


    private void sendGetFailure (HttpServletResponse response,
				 String reason)
	throws IOException
	{
	ServletOutputStream out = response.getOutputStream();

	out.println ("<html>");
	out.print ("<head><title>Poster Servlet Output Error");
	out.println ("</title></head><body><br><p><b>");
	out.println (reason);
	out.println ("</b></p><br></body></html>");
	}	// End of sendGetFailure().


    private void clearTempDir()
	{
	// Get access to the temporary file directory.
	File tempDir = null;
	try
	    {
	    tempDir = new File (posterTempDir);
	    }
	catch (Exception e)
	    {
	    // Path doesn't exist.
/*	    // Log the error for the SysAdmin.
	    log ("PosterServlet:   Unable to access temp directory :" +
		 posterTempDir + ":  Please check the permissions.");
*/
	    return;
	    }

	// Make sure that it's a directory.
	if (!tempDir.isDirectory())
	    {
/*	    // Not a directory.  Note it and bail.
	    log ("PosterServlet:  The temp directory :" +
		 posterTempDir + ": is *not* a directory!");
*/
	    return;
	    }


	// Get list of all of the files in the temporary directory.
	String[] fileNameList = null;
	try
	    {
	    fileNameList = tempDir.list();
	    }
	catch (SecurityException se)
	    {
	    // Not allowed to muck with the directory.
	    se.printStackTrace();

/*	    // Log the error for the SysAdmin.
	    log ("PosterServlet:   Unable to list temp directory :" +
		 posterTempDir + ":  Please check the permissions.");
*/
	    return;
	    }


	// Nuke each of the files in the temporary directory.
	File curFile = null;
	String path = tempDir.getPath();
	for (int i = 0; i < fileNameList.length; i++)
	    {
	    curFile = new File (path, fileNameList[i]);
	    try 
		{
		if (!curFile.delete())
		    {
/*		    // Note the error and continue.
		    log ("PosterServlet: Unable to delete :" +
			 file.getAbsolutePath() + ":");
*/
		    }
		}
	    catch (SecurityException e)
		{
/*		// Just note the error and continue.
		log ("PosterServlet:  Not allowd to delete :" +
		     file.getAbsolutePath() +
		     ":  Please check the permissions.");
*/
		}
	    }
	}	// End of clearTempDir().

    }	// End of PosterServlet.