src/org/sonews/daemon/NNTPConnection.java
author cli
Sun, 11 Sep 2011 17:01:19 +0200
changeset 49 8df94bfd3e2f
parent 48 b78e77619152
child 101 d54786065fa3
permissions -rwxr-xr-x
Fix for #14
     1 /*
     2  *   SONEWS News Server
     3  *   see AUTHORS for the list of contributors
     4  *
     5  *   This program is free software: you can redistribute it and/or modify
     6  *   it under the terms of the GNU General Public License as published by
     7  *   the Free Software Foundation, either version 3 of the License, or
     8  *   (at your option) any later version.
     9  *
    10  *   This program is distributed in the hope that it will be useful,
    11  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
    12  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    13  *   GNU General Public License for more details.
    14  *
    15  *   You should have received a copy of the GNU General Public License
    16  *   along with this program.  If not, see <http://www.gnu.org/licenses/>.
    17  */
    18 package org.sonews.daemon;
    19 
    20 import java.io.IOException;
    21 import java.net.InetSocketAddress;
    22 import java.net.SocketException;
    23 import java.nio.ByteBuffer;
    24 import java.nio.CharBuffer;
    25 import java.nio.channels.ClosedChannelException;
    26 import java.nio.channels.SelectionKey;
    27 import java.nio.channels.SocketChannel;
    28 import java.nio.charset.Charset;
    29 import java.util.Arrays;
    30 import java.util.Timer;
    31 import java.util.TimerTask;
    32 import java.util.logging.Level;
    33 import org.sonews.daemon.command.Command;
    34 import org.sonews.storage.Article;
    35 import org.sonews.storage.Group;
    36 import org.sonews.storage.StorageBackendException;
    37 import org.sonews.util.Log;
    38 import org.sonews.util.Stats;
    39 
    40 /**
    41  * For every SocketChannel (so TCP/IP connection) there is an instance of
    42  * this class.
    43  * @author Christian Lins
    44  * @since sonews/0.5.0
    45  */
    46 public final class NNTPConnection {
    47 
    48 	public static final String NEWLINE = "\r\n";    // RFC defines this as newline
    49 	public static final String MESSAGE_ID_PATTERN = "<[^>]+>";
    50 	private static final Timer cancelTimer = new Timer(true); // Thread-safe? True for run as daemon
    51 	/** SocketChannel is generally thread-safe */
    52 	private SocketChannel channel = null;
    53 	private Charset charset = Charset.forName("UTF-8");
    54 	private Command command = null;
    55 	private Article currentArticle = null;
    56 	private Group currentGroup = null;
    57 	private volatile long lastActivity = System.currentTimeMillis();
    58 	private ChannelLineBuffers lineBuffers = new ChannelLineBuffers();
    59 	private int readLock = 0;
    60 	private final Object readLockGate = new Object();
    61 	private SelectionKey writeSelKey = null;
    62 
    63 	public NNTPConnection(final SocketChannel channel)
    64 			throws IOException {
    65 		if (channel == null) {
    66 			throw new IllegalArgumentException("channel is null");
    67 		}
    68 
    69 		this.channel = channel;
    70 		Stats.getInstance().clientConnect();
    71 	}
    72 
    73 	/**
    74 	 * Tries to get the read lock for this NNTPConnection. This method is Thread-
    75 	 * safe and returns true of the read lock was successfully set. If the lock
    76 	 * is still hold by another Thread the method returns false.
    77 	 */
    78 	boolean tryReadLock() {
    79 		// As synchronizing simple types may cause deadlocks,
    80 		// we use a gate object.
    81 		synchronized (readLockGate) {
    82 			if (readLock != 0) {
    83 				return false;
    84 			} else {
    85 				readLock = Thread.currentThread().hashCode();
    86 				return true;
    87 			}
    88 		}
    89 	}
    90 
    91 	/**
    92 	 * Releases the read lock in a Thread-safe way.
    93 	 * @throws IllegalMonitorStateException if a Thread not holding the lock
    94 	 * tries to release it.
    95 	 */
    96 	void unlockReadLock() {
    97 		synchronized (readLockGate) {
    98 			if (readLock == Thread.currentThread().hashCode()) {
    99 				readLock = 0;
   100 			} else {
   101 				throw new IllegalMonitorStateException();
   102 			}
   103 		}
   104 	}
   105 
   106 	/**
   107 	 * @return Current input buffer of this NNTPConnection instance.
   108 	 */
   109 	public ByteBuffer getInputBuffer() {
   110 		return this.lineBuffers.getInputBuffer();
   111 	}
   112 
   113 	/**
   114 	 * @return Output buffer of this NNTPConnection which has at least one byte
   115 	 * free storage.
   116 	 */
   117 	public ByteBuffer getOutputBuffer() {
   118 		return this.lineBuffers.getOutputBuffer();
   119 	}
   120 
   121 	/**
   122 	 * @return ChannelLineBuffers instance associated with this NNTPConnection.
   123 	 */
   124 	public ChannelLineBuffers getBuffers() {
   125 		return this.lineBuffers;
   126 	}
   127 
   128 	/**
   129 	 * @return true if this connection comes from a local remote address.
   130 	 */
   131 	public boolean isLocalConnection() {
   132 		return ((InetSocketAddress) this.channel.socket().getRemoteSocketAddress()).getHostName().equalsIgnoreCase("localhost");
   133 	}
   134 
   135 	void setWriteSelectionKey(SelectionKey selKey) {
   136 		this.writeSelKey = selKey;
   137 	}
   138 
   139 	public void shutdownInput() {
   140 		try {
   141 			// Closes the input line of the channel's socket, so no new data
   142 			// will be received and a timeout can be triggered.
   143 			this.channel.socket().shutdownInput();
   144 		} catch (IOException ex) {
   145 			Log.get().warning("Exception in NNTPConnection.shutdownInput(): " + ex);
   146 		}
   147 	}
   148 
   149 	public void shutdownOutput() {
   150 		cancelTimer.schedule(new TimerTask() {
   151 			@Override
   152 			public void run() {
   153 				try {
   154 					// Closes the output line of the channel's socket.
   155 					channel.socket().shutdownOutput();
   156 					channel.close();
   157 				} catch (SocketException ex) {
   158 					// Socket was already disconnected
   159 					Log.get().info("NNTPConnection.shutdownOutput(): " + ex);
   160 				} catch (Exception ex) {
   161 					Log.get().warning("NNTPConnection.shutdownOutput(): " + ex);
   162 				}
   163 			}
   164 		}, 3000);
   165 	}
   166 
   167 	public SocketChannel getSocketChannel() {
   168 		return this.channel;
   169 	}
   170 
   171 	public Article getCurrentArticle() {
   172 		return this.currentArticle;
   173 	}
   174 
   175 	public Charset getCurrentCharset() {
   176 		return this.charset;
   177 	}
   178 
   179 	/**
   180 	 * @return The currently selected communication channel (not SocketChannel)
   181 	 */
   182 	public Group getCurrentChannel() {
   183 		return this.currentGroup;
   184 	}
   185 
   186 	public void setCurrentArticle(final Article article) {
   187 		this.currentArticle = article;
   188 	}
   189 
   190 	public void setCurrentGroup(final Group group) {
   191 		this.currentGroup = group;
   192 	}
   193 
   194 	public long getLastActivity() {
   195 		return this.lastActivity;
   196 	}
   197 
   198 	/**
   199 	 * Due to the readLockGate there is no need to synchronize this method.
   200 	 * @param raw
   201 	 * @throws IllegalArgumentException if raw is null.
   202 	 * @throws IllegalStateException if calling thread does not own the readLock.
   203 	 */
   204 	void lineReceived(byte[] raw) {
   205 		if (raw == null) {
   206 			throw new IllegalArgumentException("raw is null");
   207 		}
   208 
   209 		if (readLock == 0 || readLock != Thread.currentThread().hashCode()) {
   210 			throw new IllegalStateException("readLock not properly set");
   211 		}
   212 
   213 		this.lastActivity = System.currentTimeMillis();
   214 
   215 		String line = new String(raw, this.charset);
   216 
   217 		// There might be a trailing \r, but trim() is a bad idea
   218 		// as it removes also leading spaces from long header lines.
   219 		if (line.endsWith("\r")) {
   220 			line = line.substring(0, line.length() - 1);
   221 			raw = Arrays.copyOf(raw, raw.length - 1);
   222 		}
   223 
   224 		Log.get().fine("<< " + line);
   225 
   226 		if (command == null) {
   227 			command = parseCommandLine(line);
   228 			assert command != null;
   229 		}
   230 
   231 		try {
   232 			// The command object will process the line we just received
   233 			try {
   234 				command.processLine(this, line, raw);
   235 			} catch (StorageBackendException ex) {
   236 				Log.get().info("Retry command processing after StorageBackendException");
   237 
   238 				// Try it a second time, so that the backend has time to recover
   239 				command.processLine(this, line, raw);
   240 			}
   241 		} catch (ClosedChannelException ex0) {
   242 			try {
   243 				StringBuilder strBuf = new StringBuilder();
   244 				strBuf.append("Connection to ");
   245 				strBuf.append(channel.socket().getRemoteSocketAddress());
   246 				strBuf.append(" closed: ");
   247 				strBuf.append(ex0);
   248 				Log.get().info(strBuf.toString());
   249 			} catch (Exception ex0a) {
   250 				ex0a.printStackTrace();
   251 			}
   252 		} catch (Exception ex1) { // This will catch a second StorageBackendException
   253 			try {
   254 				command = null;
   255 				Log.get().log(Level.WARNING, ex1.getLocalizedMessage(), ex1);
   256 				println("403 Internal server error");
   257 
   258 				// Should we end the connection here?
   259 				// RFC says we MUST return 400 before closing the connection
   260 				shutdownInput();
   261 				shutdownOutput();
   262 			} catch (Exception ex2) {
   263 				ex2.printStackTrace();
   264 			}
   265 		}
   266 
   267 		if (command == null || command.hasFinished()) {
   268 			command = null;
   269 			charset = Charset.forName("UTF-8"); // Reset to default
   270 		}
   271 	}
   272 
   273 	/**
   274 	 * This method determines the fitting command processing class.
   275 	 * @param line
   276 	 * @return
   277 	 */
   278 	private Command parseCommandLine(String line) {
   279 		String cmdStr = line.split(" ")[0];
   280 		return CommandSelector.getInstance().get(cmdStr);
   281 	}
   282 
   283 	/**
   284 	 * Puts the given line into the output buffer, adds a newline character
   285 	 * and returns. The method returns immediately and does not block until
   286 	 * the line was sent. If line is longer than 510 octets it is split up in
   287 	 * several lines. Each line is terminated by \r\n (NNTPConnection.NEWLINE).
   288 	 * @param line
   289 	 */
   290 	public void println(final CharSequence line, final Charset charset)
   291 			throws IOException {
   292 		writeToChannel(CharBuffer.wrap(line), charset, line);
   293 		writeToChannel(CharBuffer.wrap(NEWLINE), charset, null);
   294 	}
   295 
   296 	/**
   297 	 * Writes the given raw lines to the output buffers and finishes with
   298 	 * a newline character (\r\n).
   299 	 * @param rawLines
   300 	 */
   301 	public void println(final byte[] rawLines)
   302 			throws IOException {
   303 		this.lineBuffers.addOutputBuffer(ByteBuffer.wrap(rawLines));
   304 		writeToChannel(CharBuffer.wrap(NEWLINE), charset, null);
   305 	}
   306 
   307 	/**
   308 	 * Encodes the given CharBuffer using the given Charset to a bunch of
   309 	 * ByteBuffers (each 512 bytes large) and enqueues them for writing at the
   310 	 * connected SocketChannel.
   311 	 * @throws java.io.IOException
   312 	 */
   313 	private void writeToChannel(CharBuffer characters, final Charset charset,
   314 			CharSequence debugLine)
   315 			throws IOException {
   316 		if (!charset.canEncode()) {
   317 			Log.get().severe("FATAL: Charset " + charset + " cannot encode!");
   318 			return;
   319 		}
   320 
   321 		// Write characters to output buffers
   322 		LineEncoder lenc = new LineEncoder(characters, charset);
   323 		lenc.encode(lineBuffers);
   324 
   325 		enableWriteEvents(debugLine);
   326 	}
   327 
   328 	private void enableWriteEvents(CharSequence debugLine) {
   329 		// Enable OP_WRITE events so that the buffers are processed
   330 		try {
   331 			this.writeSelKey.interestOps(SelectionKey.OP_WRITE);
   332 			ChannelWriter.getInstance().getSelector().wakeup();
   333 		} catch (Exception ex) // CancelledKeyException and ChannelCloseException
   334 		{
   335 			Log.get().warning("NNTPConnection.writeToChannel(): " + ex);
   336 			return;
   337 		}
   338 
   339 		// Update last activity timestamp
   340 		this.lastActivity = System.currentTimeMillis();
   341 		if (debugLine != null) {
   342 			Log.get().fine(">> " + debugLine);
   343 		}
   344 	}
   345 
   346 	public void println(final CharSequence line)
   347 			throws IOException {
   348 		println(line, charset);
   349 	}
   350 
   351 	public void print(final String line)
   352 			throws IOException {
   353 		writeToChannel(CharBuffer.wrap(line), charset, line);
   354 	}
   355 
   356 	public void setCurrentCharset(final Charset charset) {
   357 		this.charset = charset;
   358 	}
   359 
   360 	void setLastActivity(long timestamp) {
   361 		this.lastActivity = timestamp;
   362 	}
   363 }