net.voidfunction.rm.common.FileServlet.java Source code

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Here is the source code for net.voidfunction.rm.common.FileServlet.java

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/*
 * --------------------------
 * |    Ring Machine 2      |
 * |                        |
 * |         /---\          |
 * |         |   |          |
 * |         \---/          |
 * |                        |
 * | The Crowdsourced CDN   |
 * --------------------------
 * 
 * Copyright (C) 2012 Eric Goodwin
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to
 * deal in the Software without restriction, including without limitation the
 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
 * sell copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */

package net.voidfunction.rm.common;

import java.io.IOException;
import java.io.InputStream;

import javax.servlet.ServletException;
import javax.servlet.http.*;

import org.apache.commons.codec.binary.Hex;
import org.apache.commons.io.IOUtils;

/**
 * Servlet whose responsibility it is to act as a download server for all files in the
 * node's FileRepository. For the master node, it provides hooks to redirect the users
 * to worker nodes and a means to track downloads.
 */
public class FileServlet extends HttpServlet {

    private static final long serialVersionUID = 8461560600264423624L;

    private Node node;
    private FileLocator locator;
    private FileDownloadListener dlListener;

    /**
     * Creates a new FileServlet. locator and dlListener may be null if their
     * functionality is not needed (e.g. in worker nodes)
     * @param node
     * @param locator
     * @param dlListener
     */
    public FileServlet(Node node, FileLocator locator, FileDownloadListener dlListener) {
        this.node = node;
        this.locator = locator;
        this.dlListener = dlListener;
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        request.getSession().setMaxInactiveInterval(120);
        response.setHeader("Date", HTTPUtils.getServerTime(0));

        // Parse the filename and the ID out of the URL
        String[] urlParts = request.getRequestURI().substring(1).split("/");
        if (urlParts.length < 2) {
            response.setStatus(HttpServletResponse.SC_BAD_REQUEST);
            return;
        }
        String fileID = urlParts[1];
        String fileName = "";
        if (urlParts.length > 2)
            fileName = urlParts[2];

        String logOut = "File " + fileID + " (" + fileName + ") requested by " + request.getRemoteHost()
                + " [Result: ";

        RMFile file = node.getFileRepository().getFileById(fileID);
        if (file == null) {
            // File  with given ID not found - no redirect for you.
            logOut += "Not found]";
            node.getLog().info(logOut);

            response.setStatus(HttpServletResponse.SC_NOT_FOUND);
            response.getWriter().write("<b>404 Not Found</b><br/>Could not find a file with ID " + fileID);
            return;
        }

        boolean workerDL = (fileName.equals("Worker-Download"));
        if (workerDL)
            logOut += " (Worker Download) ";

        // Let the download listener know, if any, but don't count worker downloads
        if (dlListener != null && !workerDL)
            dlListener.fileDownloaded(file);

        String redirURL = null;
        if (locator != null)
            redirURL = (String) request.getSession().getAttribute("fileURL-" + fileID);
        if (redirURL == null && locator != null)
            redirURL = locator.locateURL(fileID, fileName);
        if (redirURL != null) {
            node.getLog().debug("Found redirect URL: " + redirURL);
            request.getSession().setAttribute("fileURL-" + fileID, redirURL);
            // Redirect to the new URL
            logOut += "Redirect]";
            node.getLog().info(logOut);

            response.setStatus(HttpServletResponse.SC_MOVED_TEMPORARILY);
            response.setHeader("Location", redirURL);
        } else {
            // We have to try to find it ourselves

            logOut += "Found locally]";
            node.getLog().info(logOut);

            // Caching magic - we can safely assume the file won't change
            String etag = Hex.encodeHexString(file.getHash());
            response.setHeader("ETag", etag);
            String ifModifiedSince = request.getHeader("If-Modified-Since");
            String ifNoneMatch = request.getHeader("If-None-Match");
            boolean etagMatch = (ifNoneMatch != null) && (ifNoneMatch.equals(etag));

            if (ifModifiedSince != null || etagMatch) {
                response.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
                response.setHeader("Last-Modified", ifModifiedSince);
            } else {
                // Send the HTTP response and file data
                response.setStatus(HttpServletResponse.SC_OK);
                response.setHeader("Expires", HTTPUtils.getServerTime(3600));
                response.setHeader("Cache-Control", "max-age=3600");
                response.setContentType(file.getMimetype());
                response.setHeader("Content-Length", String.valueOf(file.getSize()));

                // Stream the file data to the output stream using Apache IOUtils
                InputStream fileIn = node.getFileRepository().getFileData(fileID);
                IOUtils.copyLarge(fileIn, response.getOutputStream());
            }
        }
    }

}