1 /*

     2  * Copyright 2008-2009 Sun Microsystems, Inc.  All Rights Reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.  Sun designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Sun in the LICENSE file that accompanied this code.

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    14  * version 2 for more details (a copy is included in the LICENSE file that

    15  * accompanied this code).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

    22  * CA 95054 USA or visit www.sun.com if you need additional information or

    23  * have any questions.

    24  */

    25 

    26 package sun.nio.ch;

    27 

    28 import java.nio.channels.*;

    29 import java.util.concurrent.*;

    30 import java.io.IOException;

    31 import java.io.FileDescriptor;

    32 import java.net.InetSocketAddress;

    33 import java.util.concurrent.atomic.AtomicBoolean;

    34 import java.security.AccessControlContext;

    35 import java.security.AccessController;

    36 import java.security.PrivilegedAction;

    37 

    38 /**

    39  * Unix implementation of AsynchronousServerSocketChannel

    40  */

    41 

    42 class UnixAsynchronousServerSocketChannelImpl

    43     extends AsynchronousServerSocketChannelImpl

    44     implements Port.PollableChannel

    45 {

    46     private final static NativeDispatcher nd = new SocketDispatcher();

    47 

    48     private final Port port;

    49     private final int fdVal;

    50 

    51     // flag to indicate an accept is outstanding

    52     private final AtomicBoolean accepting = new AtomicBoolean();

    53     private void enableAccept() {

    54         accepting.set(false);

    55     }

    56 

    57     // used to ensure that the context for an asynchronous accept is visible

    58     // the pooled thread that handles the I/O event

    59     private final Object updateLock = new Object();

    60 

    61     // pending accept

    62     private PendingFuture<AsynchronousSocketChannel,Object> pendingAccept;

    63 

    64     // context for permission check when security manager set

    65     private AccessControlContext acc;

    66 

    67 

    68     UnixAsynchronousServerSocketChannelImpl(Port port)

    69         throws IOException

    70     {

    71         super(port);

    72 

    73         try {

    74             IOUtil.configureBlocking(fd, false);

    75         } catch (IOException x) {

    76             nd.close(fd);  // prevent leak

    77             throw x;

    78         }

    79         this.port = port;

    80         this.fdVal = IOUtil.fdVal(fd);

    81 

    82         // add mapping from file descriptor to this channel

    83         port.register(fdVal, this);

    84     }

    85 

    86     // returns and clears the result of a pending accept

    87     private PendingFuture<AsynchronousSocketChannel,Object> grabPendingAccept() {

    88         synchronized (updateLock) {

    89             PendingFuture<AsynchronousSocketChannel,Object> result = pendingAccept;

    90             pendingAccept = null;

    91             return result;

    92         }

    93     }

    94 

    95     @Override

    96     void implClose() throws IOException {

    97         // remove the mapping

    98         port.unregister(fdVal);

    99 

   100         // close file descriptor

   101         nd.close(fd);

   102 

   103         // if there is a pending accept then complete it

   104         final PendingFuture<AsynchronousSocketChannel,Object> result =

   105             grabPendingAccept();

   106         if (result != null) {

   107             // discard the stack trace as otherwise it may appear that implClose

   108             // has thrown the exception.

   109             AsynchronousCloseException x = new AsynchronousCloseException();

   110             x.setStackTrace(new StackTraceElement[0]);

   111             result.setFailure(x);

   112 

   113             // invoke by submitting task rather than directly

   114             Invoker.invokeIndirectly(result.handler(), result);

   115         }

   116     }

   117 

   118     @Override

   119     public AsynchronousChannelGroupImpl group() {

   120         return port;

   121     }

   122 

   123     /**

   124      * Invoked by event handling thread when listener socket is polled

   125      */

   126     @Override

   127     public void onEvent(int events) {

   128         PendingFuture<AsynchronousSocketChannel,Object> result = grabPendingAccept();

   129         if (result == null)

   130             return; // may have been grabbed by asynchronous close

   131 

   132         // attempt to accept connection

   133         FileDescriptor newfd = new FileDescriptor();

   134         InetSocketAddress[] isaa = new InetSocketAddress[1];

   135         boolean accepted = false;

   136         try {

   137             begin();

   138             int n = accept0(this.fd, newfd, isaa);

   139 

   140             // spurious wakeup, is this possible?

   141             if (n == IOStatus.UNAVAILABLE) {

   142                 synchronized (updateLock) {

   143                     this.pendingAccept = result;

   144                 }

   145                 port.startPoll(fdVal, Port.POLLIN);

   146                 return;

   147             }

   148 

   149             // connection accepted

   150             accepted = true;

   151 

   152         } catch (Throwable x) {

   153             if (x instanceof ClosedChannelException)

   154                 x = new AsynchronousCloseException();

   155             enableAccept();

   156             result.setFailure(x);

   157         } finally {

   158             end();

   159         }

   160 

   161         // Connection accepted so finish it when not holding locks.

   162         AsynchronousSocketChannel child = null;

   163         if (accepted) {

   164             try {

   165                 child = finishAccept(newfd, isaa[0], acc);

   166                 enableAccept();

   167                 result.setResult(child);

   168             } catch (Throwable x) {

   169                 enableAccept();

   170                 if (!(x instanceof IOException) && !(x instanceof SecurityException))

   171                     x = new IOException(x);

   172                 result.setFailure(x);

   173             }

   174         }

   175 

   176         // if an async cancel has already cancelled the operation then

   177         // close the new channel so as to free resources

   178         if (child != null && result.isCancelled()) {

   179             try {

   180                 child.close();

   181             } catch (IOException ignore) { }

   182         }

   183 

   184         // invoke the handler

   185         Invoker.invoke(result.handler(), result);

   186     }

   187 

   188     /**

   189      * Completes the accept by creating the AsynchronousSocketChannel for

   190      * the given file descriptor and remote address. If this method completes

   191      * with an IOException or SecurityException then the channel/file descriptor

   192      * will be closed.

   193      */

   194     private AsynchronousSocketChannel finishAccept(FileDescriptor newfd,

   195                                                    final InetSocketAddress remote,

   196                                                    AccessControlContext acc)

   197         throws IOException, SecurityException

   198     {

   199         AsynchronousSocketChannel ch = null;

   200         try {

   201             ch = new UnixAsynchronousSocketChannelImpl(port, newfd, remote);

   202         } catch (IOException x) {

   203             nd.close(newfd);

   204             throw x;

   205         }

   206 

   207         // permission check must always be in initiator's context

   208         try {

   209             if (acc != null) {

   210                 AccessController.doPrivileged(new PrivilegedAction<Void>() {

   211                     public Void run() {

   212                         SecurityManager sm = System.getSecurityManager();

   213                         if (sm != null) {

   214                             sm.checkAccept(remote.getAddress().getHostAddress(),

   215                                            remote.getPort());

   216                         }

   217                         return null;

   218                     }

   219                 }, acc);

   220             } else {

   221                 SecurityManager sm = System.getSecurityManager();

   222                 if (sm != null) {

   223                     sm.checkAccept(remote.getAddress().getHostAddress(),

   224                                    remote.getPort());

   225                 }

   226             }

   227         } catch (SecurityException x) {

   228             try {

   229                 ch.close();

   230             } catch (IOException ignore) { }

   231             throw x;

   232         }

   233         return ch;

   234     }

   235 

   236     @Override

   237     @SuppressWarnings("unchecked")

   238     public <A> Future<AsynchronousSocketChannel> accept(A attachment,

   239         final CompletionHandler<AsynchronousSocketChannel,? super A> handler)

   240     {

   241         // complete immediately if channel is closed

   242         if (!isOpen()) {

   243             CompletedFuture<AsynchronousSocketChannel,A> result = CompletedFuture

   244                 .withFailure(this, new ClosedChannelException(), attachment);

   245             Invoker.invokeIndirectly(handler, result);

   246             return result;

   247         }

   248         if (localAddress == null)

   249             throw new NotYetBoundException();

   250 

   251         // cancel was invoked with pending accept so connection may have been

   252         // dropped.

   253         if (isAcceptKilled())

   254             throw new RuntimeException("Accept not allowed due cancellation");

   255 

   256         // check and set flag to prevent concurrent accepting

   257         if (!accepting.compareAndSet(false, true))

   258             throw new AcceptPendingException();

   259 

   260         // attempt accept

   261         AbstractFuture<AsynchronousSocketChannel,A> result = null;

   262         FileDescriptor newfd = new FileDescriptor();

   263         InetSocketAddress[] isaa = new InetSocketAddress[1];

   264         try {

   265             begin();

   266 

   267             int n = accept0(this.fd, newfd, isaa);

   268             if (n == IOStatus.UNAVAILABLE) {

   269                 // no connection to accept

   270                 result = new PendingFuture<AsynchronousSocketChannel,A>(this, handler, attachment);

   271 

   272                 // need calling context when there is security manager as

   273                 // permission check may be done in a different thread without

   274                 // any application call frames on the stack

   275                 synchronized (this) {

   276                     this.acc = (System.getSecurityManager() == null) ?

   277                         null : AccessController.getContext();

   278                     this.pendingAccept =

   279                         (PendingFuture<AsynchronousSocketChannel,Object>)result;

   280                 }

   281 

   282                 // register for connections

   283                 port.startPoll(fdVal, Port.POLLIN);

   284                 return result;

   285             }

   286         } catch (Throwable x) {

   287             // accept failed

   288             if (x instanceof ClosedChannelException)

   289                 x = new AsynchronousCloseException();

   290             result = CompletedFuture.withFailure(this, x, attachment);

   291         } finally {

   292             end();

   293         }

   294 

   295         // connection accepted immediately

   296         if (result == null) {

   297             try {

   298                 AsynchronousSocketChannel ch = finishAccept(newfd, isaa[0], null);

   299                 result = CompletedFuture.withResult(this, ch, attachment);

   300             } catch (Throwable x) {

   301                 result = CompletedFuture.withFailure(this, x, attachment);

   302             }

   303         }

   304 

   305         // re-enable accepting and invoke handler

   306         enableAccept();

   307         Invoker.invokeIndirectly(handler, result);

   308         return result;

   309     }

   310 

   311     // -- Native methods --

   312 

   313     private static native void initIDs();

   314 

   315     // Accepts a new connection, setting the given file descriptor to refer to

   316     // the new socket and setting isaa[0] to the socket's remote address.

   317     // Returns 1 on success, or IOStatus.UNAVAILABLE.

   318     //

   319     private native int accept0(FileDescriptor ssfd, FileDescriptor newfd,

   320                                InetSocketAddress[] isaa)

   321         throws IOException;

   322 

   323     static {

   324         Util.load();

   325         initIDs();

   326     }

   327 }