Java tutorial
/* * This file is part of the Wayback archival access software * (http://archive-access.sourceforge.net/projects/wayback/). * * Licensed to the Internet Archive (IA) by one or more individual * contributors. * * The IA licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.archive.wayback.resourcestore.locationdb; import java.io.File; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.io.RandomAccessFile; import java.net.InetAddress; import java.net.InetSocketAddress; import java.net.Socket; import java.net.URL; import java.util.logging.Logger; import java.util.regex.Matcher; import java.util.regex.Pattern; import javax.servlet.ServletException; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.commons.httpclient.ChunkedInputStream; import org.archive.util.anvl.ANVLRecord; import org.archive.wayback.util.http.HttpRequestMessage; import org.archive.wayback.util.http.HttpResponse; import org.archive.wayback.util.webapp.AbstractRequestHandler; /** * ServletRequestContext interface which uses a ResourceFileLocationDB to * reverse proxy an incoming HTTP request for a file by name to it's actual * back-end location. This will also forward HTTP byte range requests to the * final location. * * @author brad * @version $Date$, $Revision$ */ public class FileProxyServlet extends AbstractRequestHandler { private static final Logger LOGGER = Logger.getLogger(FileProxyServlet.class.getName()); private static final int BUF_SIZE = 4096; private static final String RANGE_HTTP_HEADER = "Range"; private static final String DEFAULT_CONTENT_TYPE = "application/x-gzip"; private static final String HEADER_BYTES_PREFIX = "bytes="; private static final String HEADER_BYTES_SUFFIX = "-"; private static final String FILE_REGEX = "/([^/]*)$"; private static final String FILE_OFFSET_REGEX = "/([^/]*)/(\\d*)$"; private static final Pattern FILE_PATTERN = Pattern.compile(FILE_REGEX); private static final Pattern FILE_OFFSET_PATTERN = Pattern.compile(FILE_OFFSET_REGEX); private static final long serialVersionUID = 1L; private ResourceFileLocationDB locationDB = null; private int socketTimeoutMs = 5000; private int connectTimeoutMs = 1000; public boolean handleRequest(HttpServletRequest httpRequest, HttpServletResponse httpResponse) throws IOException, ServletException { ResourceLocation location = parseRequest(httpRequest); if (location == null) { httpResponse.sendError(HttpServletResponse.SC_BAD_REQUEST, "no/invalid name"); } else { String urls[] = locationDB.nameToUrls(location.getName()); if (urls == null || urls.length == 0) { LOGGER.warning("No locations for " + location.getName()); httpResponse.sendError(HttpServletResponse.SC_NOT_FOUND, "Unable to locate(" + location.getName() + ")"); } else { DataSource ds = null; for (String urlString : urls) { try { ds = locationToDataSource(urlString, location.getOffset()); if (ds != null) { break; } } catch (IOException e) { LOGGER.warning("failed proxy of " + urlString + " " + e.getLocalizedMessage()); } } if (ds == null) { LOGGER.warning("No successful locations for " + location.getName()); httpResponse.sendError(HttpServletResponse.SC_BAD_GATEWAY, "failed proxy of (" + location.getName() + ")"); } else { httpResponse.setStatus(HttpServletResponse.SC_OK); // BUGBUG: this will be broken for non compressed data... httpResponse.setContentType(ds.getContentType()); httpResponse.setBufferSize(BUF_SIZE); ds.copyTo(httpResponse.getOutputStream()); } } } return true; } private DataSource locationToDataSource(String location, long offset) throws IOException { DataSource ds = null; if (location.startsWith("http://")) { URL url = new URL(location); String hostname = url.getHost(); int port = url.getPort(); if (port == -1) { port = 80; } byte GET[] = "GET".getBytes(); byte HTTP11[] = "HTTP/1.1".getBytes(); InetAddress addr = InetAddress.getByName(hostname); HttpRequestMessage requestMessage = new HttpRequestMessage(GET, url.getFile().getBytes(), HTTP11); ANVLRecord headers = new ANVLRecord(); headers.addLabelValue("Host", hostname); if (offset != 0) { headers.addLabelValue(RANGE_HTTP_HEADER, HEADER_BYTES_PREFIX + String.valueOf(offset) + HEADER_BYTES_SUFFIX); } InetSocketAddress sockAddr = new InetSocketAddress(addr, port); Socket socket = new Socket(); socket.setSoTimeout(socketTimeoutMs); socket.setReceiveBufferSize(BUF_SIZE); socket.connect(sockAddr, connectTimeoutMs); OutputStream socketOut = socket.getOutputStream(); InputStream socketIn = socket.getInputStream(); socketOut.write(requestMessage.getBytes(true)); socketOut.write(headers.getUTF8Bytes()); socketOut.flush(); HttpResponse response = HttpResponse.load(socketIn); String contentType = response.getHeaders().asMap().get("Content-Type"); if (contentType == null) { contentType = "application/unknown"; } String xferEncoding = response.getHeaders().asMap().get("Transfer-Encoding"); if (xferEncoding != null) { if (xferEncoding.equals("chunked")) { socketIn = new ChunkedInputStream(socketIn); } } ds = new URLDataSource(socketIn, contentType); } else { // assume a local file path: File f = new File(location); if (f.isFile() && f.canRead()) { long size = f.length(); if (size < offset) { throw new IOException("short file " + location + " cannot" + " seek to offset " + offset); } RandomAccessFile raf = new RandomAccessFile(f, "r"); raf.seek(offset); // BUGBUG: is it compressed? ds = new FileDataSource(raf, DEFAULT_CONTENT_TYPE); } else { throw new IOException("No readable file at " + location); } } return ds; } private ResourceLocation parseRequest(HttpServletRequest request) { ResourceLocation location = null; String path = request.getRequestURI(); Matcher fo = FILE_OFFSET_PATTERN.matcher(path); if (fo.find()) { location = new ResourceLocation(fo.group(1), Long.parseLong(fo.group(2))); } else { fo = FILE_PATTERN.matcher(path); if (fo.find()) { String rangeHeader = request.getHeader(RANGE_HTTP_HEADER); if (rangeHeader != null) { if (rangeHeader.startsWith(HEADER_BYTES_PREFIX)) { rangeHeader = rangeHeader.substring(HEADER_BYTES_PREFIX.length()); if (rangeHeader.endsWith(HEADER_BYTES_SUFFIX)) { rangeHeader = rangeHeader.substring(0, rangeHeader.length() - HEADER_BYTES_SUFFIX.length()); } } location = new ResourceLocation(fo.group(1), Long.parseLong(rangeHeader)); } else { location = new ResourceLocation(fo.group(1)); } } } return location; } /** * @return the locationDB */ public ResourceFileLocationDB getLocationDB() { return locationDB; } /** * @param locationDB the locationDB to set */ public void setLocationDB(ResourceFileLocationDB locationDB) { this.locationDB = locationDB; } /** * @return the socketTimeoutMs */ public int getSocketTimeoutMs() { return socketTimeoutMs; } /** * @param socketTimeoutMs the socketTimeoutMs to set */ public void setSocketTimeoutMs(int socketTimeoutMs) { this.socketTimeoutMs = socketTimeoutMs; } /** * @return the connectTimeoutMs */ public int getConnectTimeoutMs() { return connectTimeoutMs; } /** * @param connectTimeoutMs the connectTimeoutMs to set */ public void setConnectTimeoutMs(int connectTimeoutMs) { this.connectTimeoutMs = connectTimeoutMs; } private class ResourceLocation { private String name = null; private long offset = 0; public ResourceLocation(String name, long offset) { this.name = name; this.offset = offset; } public ResourceLocation(String name) { this(name, 0); } public String getName() { return name; } public long getOffset() { return offset; } } private interface DataSource { public void copyTo(OutputStream os) throws IOException; public String getContentType(); } private class FileDataSource implements DataSource { private RandomAccessFile raf = null; private String contentType = null; public FileDataSource(RandomAccessFile raf, String contentType) { this.raf = raf; this.contentType = contentType; } public String getContentType() { return contentType; } public void copyTo(OutputStream os) throws IOException { byte[] buffer = new byte[BUF_SIZE]; try { int r = -1; while ((r = raf.read(buffer, 0, BUF_SIZE)) != -1) { os.write(buffer, 0, r); } } finally { raf.close(); } } } private class URLDataSource implements DataSource { private InputStream is = null; private String contentType = null; public URLDataSource(InputStream is, String contentType) { this.is = is; this.contentType = contentType; } public String getContentType() { return contentType; } public void copyTo(OutputStream os) throws IOException { byte[] buffer = new byte[BUF_SIZE]; try { int r = -1; while ((r = is.read(buffer, 0, BUF_SIZE)) != -1) { os.write(buffer, 0, r); } } finally { is.close(); } } } }