yacy_search_server/source/net/yacy/http/SSIHandler.java

//
//  SSIHandler
//  Copyright 2011 by Michael Peter Christen; mc@yacy.net, Frankfurt a. M., Germany
//  First released 13.04.2011 at http://yacy.net
//  
//  $LastChangedDate$
//  $LastChangedRevision$
//  $LastChangedBy$
//
//  This library is free software; you can redistribute it and/or
//  modify it under the terms of the GNU Lesser General Public
//  License as published by the Free Software Foundation; either
//  version 2.1 of the License, or (at your option) any later version.
//  
//  This library 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
//  Lesser General Public License for more details.
//  
//  You should have received a copy of the GNU Lesser General Public License
//  along with this program in the file lgpl21.txt
//  If not, see <http://www.gnu.org/licenses/>.
//

package net.yacy.http;

import java.io.IOException;
import java.io.OutputStream;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.eclipse.jetty.server.Handler;
import org.eclipse.jetty.server.HandlerContainer;

import net.yacy.kelondro.util.ByteBuffer;

/**
 * Jetty Http HandlerWrapper applying server-side includes,
 * used for trickling display of search results
 */
public class SSIHandler extends ContentModHandler implements Handler, HandlerContainer {
	
	/**
	 * constructor
	 * @param h Handler to wrap (it's output is scanned for SSI-marks)
	 */
	public SSIHandler(Handler h) {
		super(h);
	}

	@Override
	protected void doContentMod(final byte[] in, HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
		ByteBuffer buffer = new ByteBuffer(in);
		OutputStream out = response.getOutputStream();
		int off = 0; // starting offset
        int p = buffer.indexOf("<!--#".getBytes(), off);
        int q;
        while (p >= 0) {
            q = buffer.indexOf("-->".getBytes(), p + 10);
            out.write(in, off, p - off);
            out.flush();
            parseSSI(buffer, p, request, response);
            off = q + 3;
            p = buffer.indexOf("<!--#".getBytes(), off);
        }
        out.write(in, off, in.length - off);
        out.flush();
	}
	
    private static void parseSSI(final ByteBuffer in, final int off, HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        if (in.startsWith("<!--#include virtual=\"".getBytes(), off)) {
            final int q = in.indexOf("\"".getBytes(), off + 22);
            if (q > 0) {
                final String path = in.toString(off + 22, q - off - 22);
                try {
                	RequestDispatcher dispatcher = request.getRequestDispatcher("/"+path);
                	dispatcher.include(request, response);
                } catch (Exception e) {
                	// for debugging TODO: remove?
                	e.printStackTrace();
                	throw new ServletException();
                }
            }
        }
    }

}