1 /*
2  * Copyright 2014 The Netty Project
3  *
4  * The Netty Project licenses this file to you under the Apache License,
5  * version 2.0 (the "License"); you may not use this file except in compliance
6  * with the License. You may obtain a copy of the License at:
7  *
8  *   http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13  * License for the specific language governing permissions and limitations
14  * under the License.
15  */
16 package io.netty.channel.epoll;
17
18 import io.netty.buffer.ByteBuf;
19 import io.netty.buffer.ByteBufAllocator;
20 import io.netty.buffer.ByteBufUtil;
21 import io.netty.buffer.Unpooled;
22 import io.netty.channel.AbstractChannel;
23 import io.netty.channel.Channel;
24 import io.netty.channel.ChannelConfig;
25 import io.netty.channel.ChannelException;
26 import io.netty.channel.ChannelFuture;
27 import io.netty.channel.ChannelFutureListener;
28 import io.netty.channel.ChannelMetadata;
29 import io.netty.channel.ChannelOutboundBuffer;
30 import io.netty.channel.ChannelPromise;
31 import io.netty.channel.ConnectTimeoutException;
32 import io.netty.channel.EventLoop;
33 import io.netty.channel.RecvByteBufAllocator;
34 import io.netty.channel.nio.AbstractNioChannel;
35 import io.netty.channel.socket.ChannelInputShutdownEvent;
36 import io.netty.channel.socket.ChannelInputShutdownReadComplete;
37 import io.netty.channel.socket.SocketChannelConfig;
38 import io.netty.channel.unix.FileDescriptor;
39 import io.netty.channel.unix.Socket;
40 import io.netty.channel.unix.UnixChannel;
41 import io.netty.util.ReferenceCountUtil;
42
43 import java.io.IOException;
44 import java.net.InetSocketAddress;
45 import java.net.SocketAddress;
46 import java.nio.ByteBuffer;
47 import java.nio.channels.AlreadyConnectedException;
48 import java.nio.channels.ClosedChannelException;
49 import java.nio.channels.ConnectionPendingException;
50 import java.nio.channels.NotYetConnectedException;
51 import java.nio.channels.UnresolvedAddressException;
52 import java.util.concurrent.ScheduledFuture;
53 import java.util.concurrent.TimeUnit;
54
55 import static io.netty.channel.internal.ChannelUtils.WRITE_STATUS_SNDBUF_FULL;
56 import static io.netty.channel.unix.UnixChannelUtil.computeRemoteAddr;
57 import static io.netty.util.internal.ObjectUtil.checkNotNull;
58
59 abstract class AbstractEpollChannel extends AbstractChannel implements UnixChannel {
60     private static final ChannelMetadata METADATA = new ChannelMetadata(false);
61     final LinuxSocket socket;
62     /**
63      * The future of the current connection attempt.  If not null, subsequent
64      * connection attempts will fail.
65      */
66     private ChannelPromise connectPromise;
67     private ScheduledFuture<?> connectTimeoutFuture;
68     private SocketAddress requestedRemoteAddress;
69
70     private volatile SocketAddress local;
71     private volatile SocketAddress remote;
72
73     protected int flags = Native.EPOLLET;
74     boolean inputClosedSeenErrorOnRead;
75     boolean epollInReadyRunnablePending;
76
77     protected volatile boolean active;
78
79     AbstractEpollChannel(LinuxSocket fd) {
80         this(null, fd, false);
81     }
82
83     AbstractEpollChannel(Channel parent, LinuxSocket fd, boolean active) {
84         super(parent);
85         this.socket = checkNotNull(fd, "fd");
86         this.active = active;
87         if (active) {
88             // Directly cache the remote and local addresses
89             // See https://github.com/netty/netty/issues/2359
90             this.local = fd.localAddress();
91             this.remote = fd.remoteAddress();
92         }
93     }
94
95     AbstractEpollChannel(Channel parent, LinuxSocket fd, SocketAddress remote) {
96         super(parent);
97         this.socket = checkNotNull(fd, "fd");
98         this.active = true;
99         // Directly cache the remote and local addresses
100         // See https://github.com/netty/netty/issues/2359
101         this.remote = remote;
102         this.local = fd.localAddress();
103     }
104
105     static boolean isSoErrorZero(Socket fd) {
106         try {
107             return fd.getSoError() == 0;
108         } catch (IOException e) {
109             throw new ChannelException(e);
110         }
111     }
112
113     void setFlag(int flag) throws IOException {
114         if (!isFlagSet(flag)) {
115             flags |= flag;
116             modifyEvents();
117         }
118     }
119
120     void clearFlag(int flag) throws IOException {
121         if (isFlagSet(flag)) {
122             flags &= ~flag;
123             modifyEvents();
124         }
125     }
126
127     boolean isFlagSet(int flag) {
128         return (flags & flag) != 0;
129     }
130
131     @Override
132     public final FileDescriptor fd() {
133         return socket;
134     }
135
136     @Override
137     public abstract EpollChannelConfig config();
138
139     @Override
140     public boolean isActive() {
141         return active;
142     }
143
144     @Override
145     public ChannelMetadata metadata() {
146         return METADATA;
147     }
148
149     @Override
150     protected void doClose() throws Exception {
151         active = false;
152         // Even if we allow half closed sockets we should give up on reading. Otherwise we may allow a read attempt on a
153         // socket which has not even been connected yet. This has been observed to block during unit tests.
154         inputClosedSeenErrorOnRead = true;
155         try {
156             ChannelPromise promise = connectPromise;
157             if (promise != null) {
158                 // Use tryFailure() instead of setFailure() to avoid the race against cancel().
159                 promise.tryFailure(new ClosedChannelException());
160                 connectPromise = null;
161             }
162
163             ScheduledFuture<?> future = connectTimeoutFuture;
164             if (future != null) {
165                 future.cancel(false);
166                 connectTimeoutFuture = null;
167             }
168
169             if (isRegistered()) {
170                 // Need to check if we are on the EventLoop as doClose() may be triggered by the GlobalEventExecutor
171                 // if SO_LINGER is used.
172                 //
173                 // See https://github.com/netty/netty/issues/7159
174                 EventLoop loop = eventLoop();
175                 if (loop.inEventLoop()) {
176                     doDeregister();
177                 } else {
178                     loop.execute(new Runnable() {
179                         @Override
180                         public void run() {
181                             try {
182                                 doDeregister();
183                             } catch (Throwable cause) {
184                                 pipeline().fireExceptionCaught(cause);
185                             }
186                         }
187                     });
188                 }
189             }
190         } finally {
191             socket.close();
192         }
193     }
194
195     void resetCachedAddresses() {
196         local = socket.localAddress();
197         remote = socket.remoteAddress();
198     }
199
200     @Override
201     protected void doDisconnect() throws Exception {
202         doClose();
203     }
204
205     @Override
206     protected boolean isCompatible(EventLoop loop) {
207         return loop instanceof EpollEventLoop;
208     }
209
210     @Override
211     public boolean isOpen() {
212         return socket.isOpen();
213     }
214
215     @Override
216     protected void doDeregister() throws Exception {
217         ((EpollEventLoop) eventLoop()).remove(this);
218     }
219
220     @Override
221     protected final void doBeginRead() throws Exception {
222         // Channel.read() or ChannelHandlerContext.read() was called
223         final AbstractEpollUnsafe unsafe = (AbstractEpollUnsafe) unsafe();
224         unsafe.readPending = true;
225
226         // We must set the read flag here as it is possible the user didn't read in the last read loop, the
227         // executeEpollInReadyRunnable could read nothing, and if the user doesn't explicitly call read they will
228         // never get data after this.
229         setFlag(Native.EPOLLIN);
230
231         // If EPOLL ET mode is enabled and auto read was toggled off on the last read loop then we may not be notified
232         // again if we didn't consume all the data. So we force a read operation here if there maybe more data.
233         if (unsafe.maybeMoreDataToRead) {
234             unsafe.executeEpollInReadyRunnable(config());
235         }
236     }
237
238     final boolean shouldBreakEpollInReady(ChannelConfig config) {
239         return socket.isInputShutdown() && (inputClosedSeenErrorOnRead || !isAllowHalfClosure(config));
240     }
241
242     private static boolean isAllowHalfClosure(ChannelConfig config) {
243         if (config instanceof EpollDomainSocketChannelConfig) {
244             return ((EpollDomainSocketChannelConfig) config).isAllowHalfClosure();
245         }
246         return config instanceof SocketChannelConfig &&
247                 ((SocketChannelConfig) config).isAllowHalfClosure();
248     }
249
250     final void clearEpollIn() {
251         // Only clear if registered with an EventLoop as otherwise
252         if (isRegistered()) {
253             final EventLoop loop = eventLoop();
254             final AbstractEpollUnsafe unsafe = (AbstractEpollUnsafe) unsafe();
255             if (loop.inEventLoop()) {
256                 unsafe.clearEpollIn0();
257             } else {
258                 // schedule a task to clear the EPOLLIN as it is not safe to modify it directly
259                 loop.execute(new Runnable() {
260                     @Override
261                     public void run() {
262                         if (!unsafe.readPending && !config().isAutoRead()) {
263                             // Still no read triggered so clear it now
264                             unsafe.clearEpollIn0();
265                         }
266                     }
267                 });
268             }
269         } else  {
270             // The EventLoop is not registered atm so just update the flags so the correct value
271             // will be used once the channel is registered
272             flags &= ~Native.EPOLLIN;
273         }
274     }
275
276     private void modifyEvents() throws IOException {
277         if (isOpen() && isRegistered()) {
278             ((EpollEventLoop) eventLoop()).modify(this);
279         }
280     }
281
282     @Override
283     protected void doRegister() throws Exception {
284         // Just in case the previous EventLoop was shutdown abruptly, or an event is still pending on the old EventLoop
285         // make sure the epollInReadyRunnablePending variable is reset so we will be able to execute the Runnable on the
286         // new EventLoop.
287         epollInReadyRunnablePending = false;
288         ((EpollEventLoop) eventLoop()).add(this);
289     }
290
291     @Override
292     protected abstract AbstractEpollUnsafe newUnsafe();
293
294     /**
295      * Returns an off-heap copy of the specified {@link ByteBuf}, and releases the original one.
296      */
297     protected final ByteBuf newDirectBuffer(ByteBuf buf) {
298         return newDirectBuffer(buf, buf);
299     }
300
301     /**
302      * Returns an off-heap copy of the specified {@link ByteBuf}, and releases the specified holder.
303      * The caller must ensure that the holder releases the original {@link ByteBuf} when the holder is released by
304      * this method.
305      */
306     protected final ByteBuf newDirectBuffer(Object holder, ByteBuf buf) {
307         final int readableBytes = buf.readableBytes();
308         if (readableBytes == 0) {
309             ReferenceCountUtil.release(holder);
310             return Unpooled.EMPTY_BUFFER;
311         }
312
313         final ByteBufAllocator alloc = alloc();
314         if (alloc.isDirectBufferPooled()) {
315             return newDirectBuffer0(holder, buf, alloc, readableBytes);
316         }
317
318         final ByteBuf directBuf = ByteBufUtil.threadLocalDirectBuffer();
319         if (directBuf == null) {
320             return newDirectBuffer0(holder, buf, alloc, readableBytes);
321         }
322
323         directBuf.writeBytes(buf, buf.readerIndex(), readableBytes);
324         ReferenceCountUtil.safeRelease(holder);
325         return directBuf;
326     }
327
328     private static ByteBuf newDirectBuffer0(Object holder, ByteBuf buf, ByteBufAllocator alloc, int capacity) {
329         final ByteBuf directBuf = alloc.directBuffer(capacity);
330         directBuf.writeBytes(buf, buf.readerIndex(), capacity);
331         ReferenceCountUtil.safeRelease(holder);
332         return directBuf;
333     }
334
335     protected static void checkResolvable(InetSocketAddress addr) {
336         if (addr.isUnresolved()) {
337             throw new UnresolvedAddressException();
338         }
339     }
340
341     /**
342      * Read bytes into the given {@link ByteBuf} and return the amount.
343      */
344     protected final int doReadBytes(ByteBuf byteBuf) throws Exception {
345         int writerIndex = byteBuf.writerIndex();
346         int localReadAmount;
347         unsafe().recvBufAllocHandle().attemptedBytesRead(byteBuf.writableBytes());
348         if (byteBuf.hasMemoryAddress()) {
349             localReadAmount = socket.readAddress(byteBuf.memoryAddress(), writerIndex, byteBuf.capacity());
350         } else {
351             ByteBuffer buf = byteBuf.internalNioBuffer(writerIndex, byteBuf.writableBytes());
352             localReadAmount = socket.read(buf, buf.position(), buf.limit());
353         }
354         if (localReadAmount > 0) {
355             byteBuf.writerIndex(writerIndex + localReadAmount);
356         }
357         return localReadAmount;
358     }
359
360     protected final int doWriteBytes(ChannelOutboundBuffer in, ByteBuf buf) throws Exception {
361         if (buf.hasMemoryAddress()) {
362             int localFlushedAmount = socket.writeAddress(buf.memoryAddress(), buf.readerIndex(), buf.writerIndex());
363             if (localFlushedAmount > 0) {
364                 in.removeBytes(localFlushedAmount);
365                 return 1;
366             }
367         } else {
368             final ByteBuffer nioBuf = buf.nioBufferCount() == 1 ?
369                     buf.internalNioBuffer(buf.readerIndex(), buf.readableBytes()) : buf.nioBuffer();
370             int localFlushedAmount = socket.write(nioBuf, nioBuf.position(), nioBuf.limit());
371             if (localFlushedAmount > 0) {
372                 nioBuf.position(nioBuf.position() + localFlushedAmount);
373                 in.removeBytes(localFlushedAmount);
374                 return 1;
375             }
376         }
377         return WRITE_STATUS_SNDBUF_FULL;
378     }
379
380     protected abstract class AbstractEpollUnsafe extends AbstractUnsafe {
381         boolean readPending;
382         boolean maybeMoreDataToRead;
383         private EpollRecvByteAllocatorHandle allocHandle;
384         private final Runnable epollInReadyRunnable = new Runnable() {
385             @Override
386             public void run() {
387                 epollInReadyRunnablePending = false;
388                 epollInReady();
389             }
390         };
391
392         /**
393          * Called once EPOLLIN event is ready to be processed
394          */
395         abstract void epollInReady();
396
397         final void epollInBefore() {
398             maybeMoreDataToRead = false;
399         }
400
401         final void epollInFinally(ChannelConfig config) {
402             maybeMoreDataToRead = allocHandle.maybeMoreDataToRead();
403
404             if (allocHandle.isReceivedRdHup() || (readPending && maybeMoreDataToRead)) {
405                 // trigger a read again as there may be something left to read and because of epoll ET we
406                 // will not get notified again until we read everything from the socket
407                 //
408                 // It is possible the last fireChannelRead call could cause the user to call read() again, or if
409                 // autoRead is true the call to channelReadComplete would also call read, but maybeMoreDataToRead is set
410                 // to false before every read operation to prevent re-entry into epollInReady() we will not read from
411                 // the underlying OS again unless the user happens to call read again.
412                 executeEpollInReadyRunnable(config);
413             } else if (!readPending && !config.isAutoRead()) {
414                 // Check if there is a readPending which was not processed yet.
415                 // This could be for two reasons:
416                 // * The user called Channel.read() or ChannelHandlerContext.read() in channelRead(...) method
417                 // * The user called Channel.read() or ChannelHandlerContext.read() in channelReadComplete(...) method
418                 //
419                 // See https://github.com/netty/netty/issues/2254
420                 clearEpollIn();
421             }
422         }
423
424         final void executeEpollInReadyRunnable(ChannelConfig config) {
425             if (epollInReadyRunnablePending || !isActive() || shouldBreakEpollInReady(config)) {
426                 return;
427             }
428             epollInReadyRunnablePending = true;
429             eventLoop().execute(epollInReadyRunnable);
430         }
431
432         /**
433          * Called once EPOLLRDHUP event is ready to be processed
434          */
435         final void epollRdHupReady() {
436             // This must happen before we attempt to read. This will ensure reading continues until an error occurs.
437             recvBufAllocHandle().receivedRdHup();
438
439             if (isActive()) {
440                 // If it is still active, we need to call epollInReady as otherwise we may miss to
441                 // read pending data from the underlying file descriptor.
442                 // See https://github.com/netty/netty/issues/3709
443                 epollInReady();
444             } else {
445                 // Just to be safe make sure the input marked as closed.
446                 shutdownInput(true);
447             }
448
449             // Clear the EPOLLRDHUP flag to prevent continuously getting woken up on this event.
450             clearEpollRdHup();
451         }
452
453         /**
454          * Clear the {@link Native#EPOLLRDHUP} flag from EPOLL, and close on failure.
455          */
456         private void clearEpollRdHup() {
457             try {
458                 clearFlag(Native.EPOLLRDHUP);
459             } catch (IOException e) {
460                 pipeline().fireExceptionCaught(e);
461                 close(voidPromise());
462             }
463         }
464
465         /**
466          * Shutdown the input side of the channel.
467          */
468         void shutdownInput(boolean rdHup) {
469             if (!socket.isInputShutdown()) {
470                 if (isAllowHalfClosure(config())) {
471                     try {
472                         socket.shutdown(true, false);
473                     } catch (IOException ignored) {
474                         // We attempted to shutdown and failed, which means the input has already effectively been
475                         // shutdown.
476                         fireEventAndClose(ChannelInputShutdownEvent.INSTANCE);
477                         return;
478                     } catch (NotYetConnectedException ignore) {
479                         // We attempted to shutdown and failed, which means the input has already effectively been
480                         // shutdown.
481                     }
482                     clearEpollIn();
483                     pipeline().fireUserEventTriggered(ChannelInputShutdownEvent.INSTANCE);
484                 } else {
485                     close(voidPromise());
486                 }
487             } else if (!rdHup) {
488                 inputClosedSeenErrorOnRead = true;
489                 pipeline().fireUserEventTriggered(ChannelInputShutdownReadComplete.INSTANCE);
490             }
491         }
492
493         private void fireEventAndClose(Object evt) {
494             pipeline().fireUserEventTriggered(evt);
495             close(voidPromise());
496         }
497
498         @Override
499         public EpollRecvByteAllocatorHandle recvBufAllocHandle() {
500             if (allocHandle == null) {
501                 allocHandle = newEpollHandle((RecvByteBufAllocator.ExtendedHandle) super.recvBufAllocHandle());
502             }
503             return allocHandle;
504         }
505
506         /**
507          * Create a new {@link EpollRecvByteAllocatorHandle} instance.
508          * @param handle The handle to wrap with EPOLL specific logic.
509          */
510         EpollRecvByteAllocatorHandle newEpollHandle(RecvByteBufAllocator.ExtendedHandle handle) {
511             return new EpollRecvByteAllocatorHandle(handle);
512         }
513
514         @Override
515         protected final void flush0() {
516             // Flush immediately only when there's no pending flush.
517             // If there's a pending flush operation, event loop will call forceFlush() later,
518             // and thus there's no need to call it now.
519             if (!isFlagSet(Native.EPOLLOUT)) {
520                 super.flush0();
521             }
522         }
523
524         /**
525          * Called once a EPOLLOUT event is ready to be processed
526          */
527         final void epollOutReady() {
528             if (connectPromise != null) {
529                 // pending connect which is now complete so handle it.
530                 finishConnect();
531             } else if (!socket.isOutputShutdown()) {
532                 // directly call super.flush0() to force a flush now
533                 super.flush0();
534             }
535         }
536
537         protected final void clearEpollIn0() {
538             assert eventLoop().inEventLoop();
539             try {
540                 readPending = false;
541                 clearFlag(Native.EPOLLIN);
542             } catch (IOException e) {
543                 // When this happens there is something completely wrong with either the filedescriptor or epoll,
544                 // so fire the exception through the pipeline and close the Channel.
545                 pipeline().fireExceptionCaught(e);
546                 unsafe().close(unsafe().voidPromise());
547             }
548         }
549
550         @Override
551         public void connect(
552                 final SocketAddress remoteAddress, final SocketAddress localAddress, final ChannelPromise promise) {
553             if (!promise.setUncancellable() || !ensureOpen(promise)) {
554                 return;
555             }
556
557             try {
558                 if (connectPromise != null) {
559                     throw new ConnectionPendingException();
560                 }
561
562                 boolean wasActive = isActive();
563                 if (doConnect(remoteAddress, localAddress)) {
564                     fulfillConnectPromise(promise, wasActive);
565                 } else {
566                     connectPromise = promise;
567                     requestedRemoteAddress = remoteAddress;
568
569                     // Schedule connect timeout.
570                     int connectTimeoutMillis = config().getConnectTimeoutMillis();
571                     if (connectTimeoutMillis > 0) {
572                         connectTimeoutFuture = eventLoop().schedule(new Runnable() {
573                             @Override
574                             public void run() {
575                                 ChannelPromise connectPromise = AbstractEpollChannel.this.connectPromise;
576                                 if (connectPromise != null && !connectPromise.isDone()
577                                         && connectPromise.tryFailure(new ConnectTimeoutException(
578                                         "connection timed out: " + remoteAddress))) {
579                                     close(voidPromise());
580                                 }
581                             }
582                         }, connectTimeoutMillis, TimeUnit.MILLISECONDS);
583                     }
584
585                     promise.addListener(new ChannelFutureListener() {
586                         @Override
587                         public void operationComplete(ChannelFuture future) throws Exception {
588                             if (future.isCancelled()) {
589                                 if (connectTimeoutFuture != null) {
590                                     connectTimeoutFuture.cancel(false);
591                                 }
592                                 connectPromise = null;
593                                 close(voidPromise());
594                             }
595                         }
596                     });
597                 }
598             } catch (Throwable t) {
599                 closeIfClosed();
600                 promise.tryFailure(annotateConnectException(t, remoteAddress));
601             }
602         }
603
604         private void fulfillConnectPromise(ChannelPromise promise, boolean wasActive) {
605             if (promise == null) {
606                 // Closed via cancellation and the promise has been notified already.
607                 return;
608             }
609             active = true;
610
611             // Get the state as trySuccess() may trigger an ChannelFutureListener that will close the Channel.
612             // We still need to ensure we call fireChannelActive() in this case.
613             boolean active = isActive();
614
615             // trySuccess() will return false if a user cancelled the connection attempt.
616             boolean promiseSet = promise.trySuccess();
617
618             // Regardless if the connection attempt was cancelled, channelActive() event should be triggered,
619             // because what happened is what happened.
620             if (!wasActive && active) {
621                 pipeline().fireChannelActive();
622             }
623
624             // If a user cancelled the connection attempt, close the channel, which is followed by channelInactive().
625             if (!promiseSet) {
626                 close(voidPromise());
627             }
628         }
629
630         private void fulfillConnectPromise(ChannelPromise promise, Throwable cause) {
631             if (promise == null) {
632                 // Closed via cancellation and the promise has been notified already.
633                 return;
634             }
635
636             // Use tryFailure() instead of setFailure() to avoid the race against cancel().
637             promise.tryFailure(cause);
638             closeIfClosed();
639         }
640
641         private void finishConnect() {
642             // Note this method is invoked by the event loop only if the connection attempt was
643             // neither cancelled nor timed out.
644
645             assert eventLoop().inEventLoop();
646
647             boolean connectStillInProgress = false;
648             try {
649                 boolean wasActive = isActive();
650                 if (!doFinishConnect()) {
651                     connectStillInProgress = true;
652                     return;
653                 }
654                 fulfillConnectPromise(connectPromise, wasActive);
655             } catch (Throwable t) {
656                 fulfillConnectPromise(connectPromise, annotateConnectException(t, requestedRemoteAddress));
657             } finally {
658                 if (!connectStillInProgress) {
659                     // Check for null as the connectTimeoutFuture is only created if a connectTimeoutMillis > 0 is used
660                     // See https://github.com/netty/netty/issues/1770
661                     if (connectTimeoutFuture != null) {
662                         connectTimeoutFuture.cancel(false);
663                     }
664                     connectPromise = null;
665                 }
666             }
667         }
668
669         /**
670          * Finish the connect
671          */
672         private boolean doFinishConnect() throws Exception {
673             if (socket.finishConnect()) {
674                 clearFlag(Native.EPOLLOUT);
675                 if (requestedRemoteAddress instanceof InetSocketAddress) {
676                     remote = computeRemoteAddr((InetSocketAddress) requestedRemoteAddress, socket.remoteAddress());
677                 }
678                 requestedRemoteAddress = null;
679
680                 return true;
681             }
682             setFlag(Native.EPOLLOUT);
683             return false;
684         }
685     }
686
687     @Override
688     protected void doBind(SocketAddress local) throws Exception {
689         if (local instanceof InetSocketAddress) {
690             checkResolvable((InetSocketAddress) local);
691         }
692         socket.bind(local);
693         this.local = socket.localAddress();
694     }
695
696     /**
697      * Connect to the remote peer
698      */
699     protected boolean doConnect(SocketAddress remoteAddress, SocketAddress localAddress) throws Exception {
700         if (localAddress instanceof InetSocketAddress) {
701             checkResolvable((InetSocketAddress) localAddress);
702         }
703
704         InetSocketAddress remoteSocketAddr = remoteAddress instanceof InetSocketAddress
705                 ? (InetSocketAddress) remoteAddress : null;
706         if (remoteSocketAddr != null) {
707             checkResolvable(remoteSocketAddr);
708         }
709
710         if (remote != null) {
711             // Check if already connected before trying to connect. This is needed as connect(...) will not return -1
712             // and set errno to EISCONN if a previous connect(...) attempt was setting errno to EINPROGRESS and finished
713             // later.
714             throw new AlreadyConnectedException();
715         }
716
717         if (localAddress != null) {
718             socket.bind(localAddress);
719         }
720
721         boolean connected = doConnect0(remoteAddress);
722         if (connected) {
723             remote = remoteSocketAddr == null ?
724                     remoteAddress : computeRemoteAddr(remoteSocketAddr, socket.remoteAddress());
725         }
726         // We always need to set the localAddress even if not connected yet as the bind already took place.
727         //
728         // See https://github.com/netty/netty/issues/3463
729         local = socket.localAddress();
730         return connected;
731     }
732
733     private boolean doConnect0(SocketAddress remote) throws Exception {
734         boolean success = false;
735         try {
736             boolean connected = socket.connect(remote);
737             if (!connected) {
738                 setFlag(Native.EPOLLOUT);
739             }
740             success = true;
741             return connected;
742         } finally {
743             if (!success) {
744                 doClose();
745             }
746         }
747     }
748
749     @Override
750     protected SocketAddress localAddress0() {
751         return local;
752     }
753
754     @Override
755     protected SocketAddress remoteAddress0() {
756         return remote;
757     }
758 }
759