Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF 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.apache.commons.net.tftp.tftpserver; import java.io.BufferedInputStream; import java.io.BufferedOutputStream; import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.io.PrintStream; import java.net.SocketTimeoutException; import java.util.HashSet; import java.util.Iterator; import org.apache.commons.net.io.FromNetASCIIOutputStream; import org.apache.commons.net.io.ToNetASCIIInputStream; import org.apache.commons.net.tftp.*; /** * A fully multi-threaded tftp server. Can handle multiple clients at the same time. Implements RFC * 1350 and wrapping block numbers for large file support. * * To launch, just create an instance of the class. An IOException will be thrown if the server * fails to start for reasons such as port in use, port denied, etc. * * To stop, use the shutdown method. * * To check to see if the server is still running (or if it stopped because of an error), call the * isRunning() method. * * By default, events are not logged to stdout/stderr. This can be changed with the * setLog and setLogError methods. * * <p> * Example usage is below: * * <code> * public static void main(String[] args) throws Exception * { * if (args.length != 1) * { * System.out * .println("You must provide 1 argument - the base path for the server to serve from."); * System.exit(1); * } * * TFTPServer ts = new TFTPServer(new File(args[0]), new File(args[0]), GET_AND_PUT); * ts.setSocketTimeout(2000); * * System.out.println("TFTP Server running. Press enter to stop."); * new InputStreamReader(System.in).read(); * * ts.shutdown(); * System.out.println("Server shut down."); * System.exit(0); * } * * </code> * * * @author <A HREF="mailto:daniel.armbrust.list@gmail.com">Dan Armbrust</A> * @since 2.0 */ public class TFTPServer implements Runnable { private static final int DEFAULT_TFTP_PORT = 69; public static enum ServerMode { GET_ONLY, PUT_ONLY, GET_AND_PUT; } private final HashSet<TFTPTransfer> transfers_ = new HashSet<TFTPTransfer>(); private volatile boolean shutdownServer = false; private TFTP serverTftp_; private File serverReadDirectory_; private File serverWriteDirectory_; private final int port_; private Exception serverException = null; private final ServerMode mode_; /* /dev/null output stream (default) */ private static final PrintStream nullStream = new PrintStream(new OutputStream() { @Override public void write(int b) { } @Override public void write(byte[] b) throws IOException { } }); // don't have access to a logger api, so we will log to these streams, which // by default are set to a no-op logger private PrintStream log_; private PrintStream logError_; private int maxTimeoutRetries_ = 3; private int socketTimeout_; private Thread serverThread; /** * Start a TFTP Server on the default port (69). Gets and Puts occur in the specified * directories. * * The server will start in another thread, allowing this constructor to return immediately. * * If a get or a put comes in with a relative path that tries to get outside of the * serverDirectory, then the get or put will be denied. * * GET_ONLY mode only allows gets, PUT_ONLY mode only allows puts, and GET_AND_PUT allows both. * Modes are defined as int constants in this class. * * @param serverReadDirectory directory for GET requests * @param serverWriteDirectory directory for PUT requests * @param mode A value as specified above. * @throws IOException if the server directory is invalid or does not exist. */ public TFTPServer(File serverReadDirectory, File serverWriteDirectory, ServerMode mode) throws IOException { this(serverReadDirectory, serverWriteDirectory, DEFAULT_TFTP_PORT, mode, null, null); } /** * Start a TFTP Server on the specified port. Gets and Puts occur in the specified directory. * * The server will start in another thread, allowing this constructor to return immediately. * * If a get or a put comes in with a relative path that tries to get outside of the * serverDirectory, then the get or put will be denied. * * GET_ONLY mode only allows gets, PUT_ONLY mode only allows puts, and GET_AND_PUT allows both. * Modes are defined as int constants in this class. * * @param serverReadDirectory directory for GET requests * @param serverWriteDirectory directory for PUT requests * @param port the port to use * @param mode A value as specified above. * @param log Stream to write log message to. If not provided, uses System.out * @param errorLog Stream to write error messages to. If not provided, uses System.err. * @throws IOException if the server directory is invalid or does not exist. */ public TFTPServer(File serverReadDirectory, File serverWriteDirectory, int port, ServerMode mode, PrintStream log, PrintStream errorLog) throws IOException { port_ = port; mode_ = mode; log_ = (log == null ? nullStream : log); logError_ = (errorLog == null ? nullStream : errorLog); launch(serverReadDirectory, serverWriteDirectory); } /** * Set the max number of retries in response to a timeout. Default 3. Min 0. * * @param retries number of retries, must be > 0 */ public void setMaxTimeoutRetries(int retries) { if (retries < 0) { throw new RuntimeException("Invalid Value"); } maxTimeoutRetries_ = retries; } /** * Get the current value for maxTimeoutRetries * @return the max allowed number of retries */ public int getMaxTimeoutRetries() { return maxTimeoutRetries_; } /** * Set the socket timeout in milliseconds used in transfers. Defaults to the value here: * http://commons.apache.org/net/apidocs/org/apache/commons/net/tftp/TFTP.html#DEFAULT_TIMEOUT * (5000 at the time I write this) Min value of 10. * @param timeout the timeout; must be larger than 10 */ public void setSocketTimeout(int timeout) { if (timeout < 10) { throw new RuntimeException("Invalid Value"); } socketTimeout_ = timeout; } /** * The current socket timeout used during transfers in milliseconds. * @return the timeout value */ public int getSocketTimeout() { return socketTimeout_; } /* * start the server, throw an error if it can't start. */ private void launch(File serverReadDirectory, File serverWriteDirectory) throws IOException { log_.println("Starting TFTP Server on port " + port_ + ". Read directory: " + serverReadDirectory + " Write directory: " + serverWriteDirectory + " Server Mode is " + mode_); serverReadDirectory_ = serverReadDirectory.getCanonicalFile(); if (!serverReadDirectory_.exists() || !serverReadDirectory.isDirectory()) { throw new IOException("The server read directory " + serverReadDirectory_ + " does not exist"); } serverWriteDirectory_ = serverWriteDirectory.getCanonicalFile(); if (!serverWriteDirectory_.exists() || !serverWriteDirectory.isDirectory()) { throw new IOException("The server write directory " + serverWriteDirectory_ + " does not exist"); } serverTftp_ = new TFTP(); // This is the value used in response to each client. socketTimeout_ = serverTftp_.getDefaultTimeout(); // we want the server thread to listen forever. serverTftp_.setDefaultTimeout(0); serverTftp_.open(port_); serverThread = new Thread(this); serverThread.setDaemon(true); serverThread.start(); } @Override protected void finalize() throws Throwable { shutdown(); } /** * check if the server thread is still running. * * @return true if running, false if stopped. * @throws Exception throws the exception that stopped the server if the server is stopped from * an exception. */ public boolean isRunning() throws Exception { if (shutdownServer && serverException != null) { throw serverException; } return !shutdownServer; } // @Override public void run() { try { while (!shutdownServer) { TFTPPacket tftpPacket; tftpPacket = serverTftp_.receive(); TFTPTransfer tt = new TFTPTransfer(tftpPacket); synchronized (transfers_) { transfers_.add(tt); } Thread thread = new Thread(tt); thread.setDaemon(true); thread.start(); } } catch (Exception e) { if (!shutdownServer) { serverException = e; logError_.println("Unexpected Error in TFTP Server - Server shut down! + " + e); } } finally { shutdownServer = true; // set this to true, so the launching thread can check to see if it started. if (serverTftp_ != null && serverTftp_.isOpen()) { serverTftp_.close(); } } } /** * Stop the tftp server (and any currently running transfers) and release all opened network * resources. */ public void shutdown() { shutdownServer = true; synchronized (transfers_) { Iterator<TFTPTransfer> it = transfers_.iterator(); while (it.hasNext()) { it.next().shutdown(); } } try { serverTftp_.close(); } catch (RuntimeException e) { // noop } try { serverThread.join(); } catch (InterruptedException e) { // we've done the best we could, return } } /* * An instance of an ongoing transfer. */ private class TFTPTransfer implements Runnable { private final TFTPPacket tftpPacket_; private boolean shutdownTransfer = false; TFTP transferTftp_ = null; public TFTPTransfer(TFTPPacket tftpPacket) { tftpPacket_ = tftpPacket; } public void shutdown() { shutdownTransfer = true; try { transferTftp_.close(); } catch (RuntimeException e) { // noop } } // @Override public void run() { try { transferTftp_ = new TFTP(); transferTftp_.beginBufferedOps(); transferTftp_.setDefaultTimeout(socketTimeout_); transferTftp_.open(); if (tftpPacket_ instanceof TFTPReadRequestPacket) { handleRead(((TFTPReadRequestPacket) tftpPacket_)); } else if (tftpPacket_ instanceof TFTPWriteRequestPacket) { handleWrite((TFTPWriteRequestPacket) tftpPacket_); } else { log_.println("Unsupported TFTP request (" + tftpPacket_ + ") - ignored."); } } catch (Exception e) { if (!shutdownTransfer) { logError_.println("Unexpected Error in during TFTP file transfer. Transfer aborted. " + e); } } finally { try { if (transferTftp_ != null && transferTftp_.isOpen()) { transferTftp_.endBufferedOps(); transferTftp_.close(); } } catch (Exception e) { // noop } synchronized (transfers_) { transfers_.remove(this); } } } /* * Handle a tftp read request. */ private void handleRead(TFTPReadRequestPacket trrp) throws IOException, TFTPPacketException { InputStream is = null; try { if (mode_ == ServerMode.PUT_ONLY) { transferTftp_.bufferedSend(new TFTPErrorPacket(trrp.getAddress(), trrp.getPort(), TFTPErrorPacket.ILLEGAL_OPERATION, "Read not allowed by server.")); return; } try { is = new BufferedInputStream( new FileInputStream(buildSafeFile(serverReadDirectory_, trrp.getFilename(), false))); } catch (FileNotFoundException e) { transferTftp_.bufferedSend(new TFTPErrorPacket(trrp.getAddress(), trrp.getPort(), TFTPErrorPacket.FILE_NOT_FOUND, e.getMessage())); return; } catch (Exception e) { transferTftp_.bufferedSend(new TFTPErrorPacket(trrp.getAddress(), trrp.getPort(), TFTPErrorPacket.UNDEFINED, e.getMessage())); return; } if (trrp.getMode() == TFTP.NETASCII_MODE) { is = new ToNetASCIIInputStream(is); } byte[] temp = new byte[TFTPDataPacket.MAX_DATA_LENGTH]; TFTPPacket answer; int block = 1; boolean sendNext = true; int readLength = TFTPDataPacket.MAX_DATA_LENGTH; TFTPDataPacket lastSentData = null; // We are reading a file, so when we read less than the // requested bytes, we know that we are at the end of the file. while (readLength == TFTPDataPacket.MAX_DATA_LENGTH && !shutdownTransfer) { if (sendNext) { readLength = is.read(temp); if (readLength == -1) { readLength = 0; } lastSentData = new TFTPDataPacket(trrp.getAddress(), trrp.getPort(), block, temp, 0, readLength); transferTftp_.bufferedSend(lastSentData); } answer = null; int timeoutCount = 0; while (!shutdownTransfer && (answer == null || !answer.getAddress().equals(trrp.getAddress()) || answer.getPort() != trrp.getPort())) { // listen for an answer. if (answer != null) { // The answer that we got didn't come from the // expected source, fire back an error, and continue // listening. log_.println("TFTP Server ignoring message from unexpected source."); transferTftp_.bufferedSend(new TFTPErrorPacket(answer.getAddress(), answer.getPort(), TFTPErrorPacket.UNKNOWN_TID, "Unexpected Host or Port")); } try { answer = transferTftp_.bufferedReceive(); } catch (SocketTimeoutException e) { if (timeoutCount >= maxTimeoutRetries_) { throw e; } // didn't get an ack for this data. need to resend // it. timeoutCount++; transferTftp_.bufferedSend(lastSentData); continue; } } if (answer == null || !(answer instanceof TFTPAckPacket)) { if (!shutdownTransfer) { logError_.println("Unexpected response from tftp client during transfer (" + answer + "). Transfer aborted."); } break; } else { // once we get here, we know we have an answer packet // from the correct host. TFTPAckPacket ack = (TFTPAckPacket) answer; if (ack.getBlockNumber() != block) { /* * The origional tftp spec would have called on us to resend the * previous data here, however, that causes the SAS Syndrome. * http://www.faqs.org/rfcs/rfc1123.html section 4.2.3.1 The modified * spec says that we ignore a duplicate ack. If the packet was really * lost, we will time out on receive, and resend the previous data at * that point. */ sendNext = false; } else { // send the next block block++; if (block > 65535) { // wrap the block number block = 0; } sendNext = true; } } } } finally { try { if (is != null) { is.close(); } } catch (IOException e) { // noop } } } /* * handle a tftp write request. */ private void handleWrite(TFTPWriteRequestPacket twrp) throws IOException, TFTPPacketException { OutputStream bos = null; try { if (mode_ == ServerMode.GET_ONLY) { transferTftp_.bufferedSend(new TFTPErrorPacket(twrp.getAddress(), twrp.getPort(), TFTPErrorPacket.ILLEGAL_OPERATION, "Write not allowed by server.")); return; } int lastBlock = 0; String fileName = twrp.getFilename(); try { File temp = buildSafeFile(serverWriteDirectory_, fileName, true); if (temp.exists()) { transferTftp_.bufferedSend(new TFTPErrorPacket(twrp.getAddress(), twrp.getPort(), TFTPErrorPacket.FILE_EXISTS, "File already exists")); return; } bos = new BufferedOutputStream(new FileOutputStream(temp)); if (twrp.getMode() == TFTP.NETASCII_MODE) { bos = new FromNetASCIIOutputStream(bos); } } catch (Exception e) { transferTftp_.bufferedSend(new TFTPErrorPacket(twrp.getAddress(), twrp.getPort(), TFTPErrorPacket.UNDEFINED, e.getMessage())); return; } TFTPAckPacket lastSentAck = new TFTPAckPacket(twrp.getAddress(), twrp.getPort(), 0); transferTftp_.bufferedSend(lastSentAck); while (true) { // get the response - ensure it is from the right place. TFTPPacket dataPacket = null; int timeoutCount = 0; while (!shutdownTransfer && (dataPacket == null || !dataPacket.getAddress().equals(twrp.getAddress()) || dataPacket.getPort() != twrp.getPort())) { // listen for an answer. if (dataPacket != null) { // The data that we got didn't come from the // expected source, fire back an error, and continue // listening. log_.println("TFTP Server ignoring message from unexpected source."); transferTftp_.bufferedSend(new TFTPErrorPacket(dataPacket.getAddress(), dataPacket.getPort(), TFTPErrorPacket.UNKNOWN_TID, "Unexpected Host or Port")); } try { dataPacket = transferTftp_.bufferedReceive(); } catch (SocketTimeoutException e) { if (timeoutCount >= maxTimeoutRetries_) { throw e; } // It didn't get our ack. Resend it. transferTftp_.bufferedSend(lastSentAck); timeoutCount++; continue; } } if (dataPacket != null && dataPacket instanceof TFTPWriteRequestPacket) { // it must have missed our initial ack. Send another. lastSentAck = new TFTPAckPacket(twrp.getAddress(), twrp.getPort(), 0); transferTftp_.bufferedSend(lastSentAck); } else if (dataPacket == null || !(dataPacket instanceof TFTPDataPacket)) { if (!shutdownTransfer) { logError_.println("Unexpected response from tftp client during transfer (" + dataPacket + "). Transfer aborted."); } break; } else { int block = ((TFTPDataPacket) dataPacket).getBlockNumber(); byte[] data = ((TFTPDataPacket) dataPacket).getData(); int dataLength = ((TFTPDataPacket) dataPacket).getDataLength(); int dataOffset = ((TFTPDataPacket) dataPacket).getDataOffset(); if (block > lastBlock || (lastBlock == 65535 && block == 0)) { // it might resend a data block if it missed our ack // - don't rewrite the block. bos.write(data, dataOffset, dataLength); lastBlock = block; } lastSentAck = new TFTPAckPacket(twrp.getAddress(), twrp.getPort(), block); transferTftp_.bufferedSend(lastSentAck); if (dataLength < TFTPDataPacket.MAX_DATA_LENGTH) { // end of stream signal - The tranfer is complete. bos.close(); // But my ack may be lost - so listen to see if I // need to resend the ack. for (int i = 0; i < maxTimeoutRetries_; i++) { try { dataPacket = transferTftp_.bufferedReceive(); } catch (SocketTimeoutException e) { // this is the expected route - the client // shouldn't be sending any more packets. break; } if (dataPacket != null && (!dataPacket.getAddress().equals(twrp.getAddress()) || dataPacket.getPort() != twrp.getPort())) { // make sure it was from the right client... transferTftp_.bufferedSend( new TFTPErrorPacket(dataPacket.getAddress(), dataPacket.getPort(), TFTPErrorPacket.UNKNOWN_TID, "Unexpected Host or Port")); } else { // This means they sent us the last // datapacket again, must have missed our // ack. resend it. transferTftp_.bufferedSend(lastSentAck); } } // all done. break; } } } } finally { if (bos != null) { bos.close(); } } } /* * Utility method to make sure that paths provided by tftp clients do not get outside of the * serverRoot directory. */ private File buildSafeFile(File serverDirectory, String fileName, boolean createSubDirs) throws IOException { File temp = new File(serverDirectory, fileName); temp = temp.getCanonicalFile(); if (!isSubdirectoryOf(serverDirectory, temp)) { throw new IOException("Cannot access files outside of tftp server root."); } // ensure directory exists (if requested) if (createSubDirs) { createDirectory(temp.getParentFile()); } return temp; } /* * recursively create subdirectories */ private void createDirectory(File file) throws IOException { File parent = file.getParentFile(); if (parent == null) { throw new IOException("Unexpected error creating requested directory"); } if (!parent.exists()) { // recurse... createDirectory(parent); } if (parent.isDirectory()) { if (file.isDirectory()) { return; } boolean result = file.mkdir(); if (!result) { throw new IOException("Couldn't create requested directory"); } } else { throw new IOException("Invalid directory path - file in the way of requested folder"); } } /* * recursively check to see if one directory is a parent of another. */ private boolean isSubdirectoryOf(File parent, File child) { File childsParent = child.getParentFile(); if (childsParent == null) { return false; } if (childsParent.equals(parent)) { return true; } else { return isSubdirectoryOf(parent, childsParent); } } } /** * Set the stream object to log debug / informational messages. By default, this is a no-op * * @param log the stream to use for logging */ public void setLog(PrintStream log) { this.log_ = log; } /** * Set the stream object to log error messsages. By default, this is a no-op * * @param logError the stream to use for logging errors */ public void setLogError(PrintStream logError) { this.logError_ = logError; } }