Quadcap Embeddable Server

com/quadcap/http/servlets/cgi/CgiServlet.java

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package com.quadcap.http.servlets.cgi;

/* Copyright 1999 - 2003 Quadcap Software.  All rights reserved.
 *
 * This software is distributed under the Quadcap Free Software License.
 * This software may be used or modified for any purpose, personal or
 * commercial.  Open Source redistributions are permitted.  Commercial
 * redistribution of larger works derived from, or works which bundle
 * this software requires a "Commercial Redistribution License"; see
 * http://www.quadcap.com/purchase.
 *
 * Redistributions qualify as "Open Source" under  one of the following terms:
 *   
 *    Redistributions are made at no charge beyond the reasonable cost of
 *    materials and delivery.
 *
 *    Redistributions are accompanied by a copy of the Source Code or by an
 *    irrevocable offer to provide a copy of the Source Code for up to three
 *    years at the cost of materials and delivery.  Such redistributions
 *    must allow further use, modification, and redistribution of the Source
 *    Code under substantially the same terms as this license.
 *
 * Redistributions of source code must retain the copyright notices as they
 * appear in each source code file, these license terms, and the
 * disclaimer/limitation of liability set forth as paragraph 6 below.
 *
 * Redistributions in binary form must reproduce this Copyright Notice,
 * these license terms, and the disclaimer/limitation of liability set
 * forth as paragraph 6 below, in the documentation and/or other materials
 * provided with the distribution.
 *
 * The Software is provided on an "AS IS" basis.  No warranty is
 * provided that the Software is free of defects, or fit for a
 * particular purpose.  
 *
 * Limitation of Liability. Quadcap Software shall not be liable
 * for any damages suffered by the Licensee or any third party resulting
 * from use of the Software.
 */

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.OutputStream;

import java.util.Enumeration;
import java.util.Hashtable;

import javax.servlet.ServletConfig;
import javax.servlet.ServletException;

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.quadcap.util.Debug;

/**
 * This servlet class implements a CGI interface.
 * <p>
 *
 * @author Stan Bailes
 */

public class CgiServlet extends HttpServlet {
    Hashtable                   scripts         = new Hashtable();
    Hashtable                   extMap          = new Hashtable();
    String                      defaultInterp;

    /**
     * Initialize this servlet
     *
     * @param config the servlet configuration object, containing my
     *          initialization parameters
     * @exception ServletException if I can't initialize for some reason.
     */
    public void init(ServletConfig config) throws ServletException {
        super.init(config);
        Enumeration e = config.getInitParameterNames();
        defaultInterp = config.getInitParameter("defaultInterp");
        while (e.hasMoreElements()) {
            String name = e.nextElement().toString();
            if (name.startsWith(".")) {
                extMap.put(name.substring(1), config.getInitParameter(name));
            }
        }
    }
    
    /**
     * Handle an incoming request.
     *
     * @param req HttpServletRequest that encapsulates the request to
     *          the servlet 
     * @param res HttpServletResponse that encapsulates the response
     *          from the servlet
     * 
     * @exception IOException if detected when handling the request
     * @exception ServletException if the request could not be handled
     */
    protected void service(HttpServletRequest req, HttpServletResponse res)
        throws ServletException, IOException
    {
        CgiScript file = getFileForRequest(req);
        if (file == null) {
            res.sendError(HttpServletResponse.SC_NOT_FOUND);
        } else {
            file.service(req, res);
        }
    }

    /**
     * A cheesy implementation. XXX
     *
     * @param req the request for which we need to associate a file
     * @return the file name
     */
    public String getFileNameForRequest(HttpServletRequest req) {
        String uri = req.getRequestURI();
        int idx = uri.indexOf('?');
        if (idx >= 0) uri = uri.substring(0, idx);
        return uri;
    }
    
    /**
     * Return a file object which is suitable for processing the specified
     * request. 
     *
     * @param req the http request to service.
     * @return the file, or null if the file doesn't exist.
     *
     * @exception ServletException may be thrown.
     */
    public CgiScript getFileForRequest(HttpServletRequest req)
        throws ServletException
    {
        String name = getServletContext().getRealPath(req.getServletPath());
        CgiScript script = null;

        synchronized (scripts) {
            script = (CgiScript)scripts.get(name);

            if (script == null) {
                int idx = name.lastIndexOf('.');
                String ext = null;
                if (idx > 0) ext = name.substring(idx+1);
                String interp = null;
                if (ext != null) interp = (String)extMap.get(ext);
                if (interp == null) interp = defaultInterp;
                if (interp == null) {
                    throw new ServletException("No interpreter for " + name);
                }

                File f = new File(name);
                if (!f.exists()) return null;

                script = new CgiScript(this, interp, f);
                scripts.put(name, script);
                return script;
            }
        }
        return script;
    }
}