bgp/rib-impl/src/main/java/org/opendaylight/protocol/bgp/rib/impl/BGPSessionImpl.java

   1 /*
   2  * Copyright (c) 2013 Cisco Systems, Inc. and others.  All rights reserved.
   3  *
   4  * This program and the accompanying materials are made available under the
   5  * terms of the Eclipse Public License v1.0 which accompanies this distribution,
   6  * and is available at http://www.eclipse.org/legal/epl-v10.html
   7  */
   8 package org.opendaylight.protocol.bgp.rib.impl;
   9
  10 import static java.util.Objects.requireNonNull;
  11
  12 import com.google.common.annotations.VisibleForTesting;
  13 import com.google.common.base.MoreObjects;
  14 import com.google.common.base.MoreObjects.ToStringHelper;
  15 import com.google.common.collect.ImmutableSet;
  16 import io.netty.buffer.ByteBufUtil;
  17 import io.netty.channel.Channel;
  18 import io.netty.channel.ChannelFuture;
  19 import io.netty.channel.ChannelFutureListener;
  20 import io.netty.channel.ChannelHandlerContext;
  21 import io.netty.channel.SimpleChannelInboundHandler;
  22 import io.netty.util.concurrent.ScheduledFuture;
  23 import java.io.IOException;
  24 import java.nio.channels.NonWritableChannelException;
  25 import java.util.ArrayList;
  26 import java.util.Date;
  27 import java.util.HashSet;
  28 import java.util.List;
  29 import java.util.Optional;
  30 import java.util.Set;
  31 import java.util.concurrent.TimeUnit;
  32 import java.util.function.Function;
  33 import org.checkerframework.checker.lock.qual.GuardedBy;
  34 import org.checkerframework.checker.lock.qual.Holding;
  35 import org.opendaylight.protocol.bgp.parser.AsNumberUtil;
  36 import org.opendaylight.protocol.bgp.parser.BGPDocumentedException;
  37 import org.opendaylight.protocol.bgp.parser.BGPError;
  38 import org.opendaylight.protocol.bgp.parser.BgpExtendedMessageUtil;
  39 import org.opendaylight.protocol.bgp.parser.BgpTableTypeImpl;
  40 import org.opendaylight.protocol.bgp.parser.GracefulRestartUtil;
  41 import org.opendaylight.protocol.bgp.parser.spi.MultiPathSupport;
  42 import org.opendaylight.protocol.bgp.parser.spi.PeerConstraint;
  43 import org.opendaylight.protocol.bgp.parser.spi.pojo.MultiPathSupportImpl;
  44 import org.opendaylight.protocol.bgp.rib.impl.spi.BGPMessagesListener;
  45 import org.opendaylight.protocol.bgp.rib.impl.spi.BGPPeerRegistry;
  46 import org.opendaylight.protocol.bgp.rib.impl.spi.BGPSessionPreferences;
  47 import org.opendaylight.protocol.bgp.rib.impl.state.BGPSessionStateImpl;
  48 import org.opendaylight.protocol.bgp.rib.impl.state.BGPSessionStateProvider;
  49 import org.opendaylight.protocol.bgp.rib.spi.BGPSession;
  50 import org.opendaylight.protocol.bgp.rib.spi.BGPSessionListener;
  51 import org.opendaylight.protocol.bgp.rib.spi.BGPTerminationReason;
  52 import org.opendaylight.protocol.bgp.rib.spi.State;
  53 import org.opendaylight.protocol.bgp.rib.spi.state.BGPSessionState;
  54 import org.opendaylight.protocol.bgp.rib.spi.state.BGPTimersState;
  55 import org.opendaylight.protocol.bgp.rib.spi.state.BGPTransportState;
  56 import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.inet.types.rev130715.AsNumber;
  57 import org.opendaylight.yang.gen.v1.urn.ietf.params.xml.ns.yang.ietf.inet.types.rev130715.Ipv4Address;
  58 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev200120.Keepalive;
  59 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev200120.KeepaliveBuilder;
  60 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev200120.Notify;
  61 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev200120.NotifyBuilder;
  62 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev200120.Open;
  63 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev200120.Update;
  64 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev200120.open.message.BgpParameters;
  65 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev200120.open.message.bgp.parameters.OptionalCapabilities;
  66 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.message.rev200120.open.message.bgp.parameters.optional.capabilities.CParameters;
  67 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.multiprotocol.rev180329.BgpTableType;
  68 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.multiprotocol.rev180329.CParameters1;
  69 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.multiprotocol.rev180329.MpCapabilities;
  70 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.multiprotocol.rev180329.RouteRefresh;
  71 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.multiprotocol.rev180329.mp.capabilities.AddPathCapability;
  72 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.multiprotocol.rev180329.mp.capabilities.GracefulRestartCapability;
  73 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.multiprotocol.rev180329.mp.capabilities.LlGracefulRestartCapability;
  74 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.multiprotocol.rev180329.mp.capabilities.MultiprotocolCapability;
  75 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.multiprotocol.rev180329.mp.capabilities.add.path.capability.AddressFamilies;
  76 import org.opendaylight.yang.gen.v1.urn.opendaylight.params.xml.ns.yang.bgp.rib.rev180329.rib.TablesKey;
  77 import org.opendaylight.yangtools.yang.binding.ChildOf;
  78 import org.opendaylight.yangtools.yang.binding.Notification;
  79 import org.opendaylight.yangtools.yang.common.Uint8;
  80 import org.slf4j.Logger;
  81 import org.slf4j.LoggerFactory;
  82
  83 @VisibleForTesting
  84 public class BGPSessionImpl extends SimpleChannelInboundHandler<Notification> implements BGPSession,
  85         BGPSessionStateProvider, AutoCloseable {
  86
  87     private static final Logger LOG = LoggerFactory.getLogger(BGPSessionImpl.class);
  88
  89     private static final Notification KEEP_ALIVE = new KeepaliveBuilder().build();
  90
  91     private static final int KA_TO_DEADTIMER_RATIO = 3;
  92
  93     static final String END_OF_INPUT = "End of input detected. Close the session.";
  94
  95     /**
  96      * System.nanoTime value about when was sent the last message.
  97      */
  98     @VisibleForTesting
  99     private long lastMessageSentAt;
 100
 101     /**
 102      * System.nanoTime value about when was received the last message.
 103      */
 104     private long lastMessageReceivedAt;
 105
 106     private final BGPSessionListener listener;
 107
 108     private final BGPSynchronization sync;
 109
 110     private int kaCounter = 0;
 111
 112     private final Channel channel;
 113
 114     @GuardedBy("this")
 115     private State state = State.OPEN_CONFIRM;
 116
 117     private final Set<BgpTableType> tableTypes;
 118     private final List<AddressFamilies> addPathTypes;
 119     private final long holdTimerNanos;
 120     private final long keepAliveNanos;
 121     private final AsNumber asNumber;
 122     private final Ipv4Address bgpId;
 123     private final BGPPeerRegistry peerRegistry;
 124     private final ChannelOutputLimiter limiter;
 125     private final BGPSessionStateImpl sessionState;
 126     private final GracefulRestartCapability gracefulCapability;
 127     private final LlGracefulRestartCapability llGracefulCapability;
 128     private boolean terminationReasonNotified;
 129
 130     public BGPSessionImpl(final BGPSessionListener listener, final Channel channel, final Open remoteOpen,
 131             final BGPSessionPreferences localPreferences, final BGPPeerRegistry peerRegistry) {
 132         this(listener, channel, remoteOpen, localPreferences.getHoldTime(), peerRegistry);
 133     }
 134
 135     public BGPSessionImpl(final BGPSessionListener listener, final Channel channel, final Open remoteOpen,
 136             final int localHoldTimer, final BGPPeerRegistry peerRegistry) {
 137         this.listener = requireNonNull(listener);
 138         this.channel = requireNonNull(channel);
 139         this.limiter = new ChannelOutputLimiter(this);
 140         this.channel.pipeline().addLast(this.limiter);
 141
 142         final int remoteHoldTimer = remoteOpen.getHoldTimer().toJava();
 143         final int holdTimerValue = Math.min(remoteHoldTimer, localHoldTimer);
 144         LOG.info("BGP HoldTimer new value: {}", holdTimerValue);
 145         this.holdTimerNanos = TimeUnit.SECONDS.toNanos(holdTimerValue);
 146         this.keepAliveNanos = TimeUnit.SECONDS.toNanos(holdTimerValue / KA_TO_DEADTIMER_RATIO);
 147
 148         this.asNumber = AsNumberUtil.advertizedAsNumber(remoteOpen);
 149         this.peerRegistry = peerRegistry;
 150         this.sessionState = new BGPSessionStateImpl();
 151
 152         final Set<TablesKey> tts = new HashSet<>();
 153         final Set<BgpTableType> tats = new HashSet<>();
 154         final List<AddressFamilies> addPathCapabilitiesList = new ArrayList<>();
 155         final List<BgpParameters> bgpParameters = remoteOpen.getBgpParameters();
 156         if (bgpParameters != null) {
 157             for (final BgpParameters param : bgpParameters) {
 158                 for (final OptionalCapabilities optCapa : param.nonnullOptionalCapabilities()) {
 159                     final CParameters cParam = optCapa.getCParameters();
 160                     final CParameters1 cParam1 = cParam.augmentation(CParameters1.class);
 161                     if (cParam1 != null) {
 162                         final MultiprotocolCapability multi = cParam1.getMultiprotocolCapability();
 163                         if (multi != null) {
 164                             final TablesKey tt = new TablesKey(multi.getAfi(), multi.getSafi());
 165                             LOG.trace("Added table type to sync {}", tt);
 166                             tts.add(tt);
 167                             tats.add(new BgpTableTypeImpl(tt.getAfi(), tt.getSafi()));
 168                         } else {
 169                             final AddPathCapability addPathCap = cParam1.getAddPathCapability();
 170                             if (addPathCap != null) {
 171                                 addPathCapabilitiesList.addAll(addPathCap.getAddressFamilies());
 172                             }
 173                         }
 174                     }
 175                 }
 176             }
 177             this.gracefulCapability = findSingleCapability(bgpParameters, "Graceful Restart",
 178                 CParameters1::getGracefulRestartCapability).orElse(GracefulRestartUtil.EMPTY_GR_CAPABILITY);
 179             this.llGracefulCapability = findSingleCapability(bgpParameters, "Long-lived Graceful Restart",
 180                 CParameters1::getLlGracefulRestartCapability).orElse(GracefulRestartUtil.EMPTY_LLGR_CAPABILITY);
 181         } else {
 182             this.gracefulCapability = GracefulRestartUtil.EMPTY_GR_CAPABILITY;
 183             this.llGracefulCapability = GracefulRestartUtil.EMPTY_LLGR_CAPABILITY;
 184         }
 185
 186         this.sync = new BGPSynchronization(this.listener, tts);
 187         this.tableTypes = tats;
 188         this.addPathTypes = addPathCapabilitiesList;
 189
 190         if (!this.addPathTypes.isEmpty()) {
 191             addDecoderConstraint(MultiPathSupport.class,
 192                 MultiPathSupportImpl.createParserMultiPathSupport(this.addPathTypes));
 193         }
 194
 195         if (holdTimerValue != 0) {
 196             channel.eventLoop().schedule(this::handleHoldTimer, this.holdTimerNanos, TimeUnit.NANOSECONDS);
 197             channel.eventLoop().schedule(this::handleKeepaliveTimer, this.keepAliveNanos, TimeUnit.NANOSECONDS);
 198         }
 199         this.bgpId = remoteOpen.getBgpIdentifier();
 200         this.sessionState.advertizeCapabilities(holdTimerValue, channel.remoteAddress(), channel.localAddress(),
 201                 this.tableTypes, bgpParameters);
 202     }
 203
 204     private static <T extends ChildOf<MpCapabilities>> Optional<T> findSingleCapability(
 205             final List<BgpParameters> bgpParameters, final String name, final Function<CParameters1, T> extractor) {
 206         final List<T> found = new ArrayList<>(1);
 207         for (BgpParameters bgpParams : bgpParameters) {
 208             for (OptionalCapabilities optCapability : bgpParams.nonnullOptionalCapabilities()) {
 209                 final CParameters cparam = optCapability.getCParameters();
 210                 if (cparam != null) {
 211                     final CParameters1 augment = cparam.augmentation(CParameters1.class);
 212                     if (augment != null) {
 213                         final T capa = extractor.apply(augment);
 214                         if (capa != null) {
 215                             found.add(capa);
 216                         }
 217                     }
 218                 }
 219             }
 220         }
 221
 222         final Set<T> set = ImmutableSet.copyOf(found);
 223         switch (set.size()) {
 224             case 0:
 225                 LOG.debug("{} capability not advertised.", name);
 226                 return Optional.empty();
 227             case 1:
 228                 return Optional.of(found.get(0));
 229             default:
 230                 LOG.warn("Multiple instances of {} capability advertised: {}, ignoring.", name, set);
 231                 return Optional.empty();
 232         }
 233     }
 234
 235     /**
 236      * Set the extend message coder for current channel.
 237      * The reason for separating this part from constructor is, in #channel.pipeline().replace(..), the
 238      * invokeChannelRead() will be invoked after the original message coder handler got removed. And there
 239      * is chance that before the session instance is fully initiated (constructor returns), a KeepAlive
 240      * message arrived already in the channel buffer. Thus #AbstractBGPSessionNegotiator.handleMessage(..)
 241      * gets invoked again and a deadlock is caused.  A BGP final state machine error will happen as BGP
 242      * negotiator is still in OPEN_SENT state as the session constructor hasn't returned yet.
 243      */
 244     public synchronized void setChannelExtMsgCoder(final Open remoteOpen) {
 245         final boolean enableExMess = BgpExtendedMessageUtil.advertizedBgpExtendedMessageCapability(remoteOpen);
 246         if (enableExMess) {
 247             BGPMessageHeaderDecoder.enableExtendedMessages(this.channel);
 248         }
 249     }
 250
 251     @Override
 252     public synchronized void close() {
 253         if (this.state != State.IDLE) {
 254             if (!this.terminationReasonNotified) {
 255                 this.writeAndFlush(new NotifyBuilder().setErrorCode(BGPError.CEASE.getCode())
 256                         .setErrorSubcode(BGPError.CEASE.getSubcode()).build());
 257             }
 258             this.closeWithoutMessage();
 259         }
 260     }
 261
 262     /**
 263      * Handles incoming message based on their type.
 264      *
 265      * @param msg incoming message
 266      */
 267     void handleMessage(final Notification msg) {
 268         // synchronize on listener and then on this object to ensure correct order of locking
 269         synchronized (this.listener) {
 270             synchronized (this) {
 271                 if (this.state == State.IDLE) {
 272                     return;
 273                 }
 274                 try {
 275                     // Update last reception time
 276                     this.lastMessageReceivedAt = System.nanoTime();
 277
 278                     if (msg instanceof Open) {
 279                         // Open messages should not be present here
 280                         terminate(new BGPDocumentedException(null, BGPError.FSM_ERROR));
 281                     } else if (msg instanceof Notify) {
 282                         final Notify notify = (Notify) msg;
 283                         // Notifications are handled internally
 284                         LOG.info("Session closed because Notification message received: {} / {}, data={}",
 285                                 notify.getErrorCode(),
 286                                 notify.getErrorSubcode(),
 287                                 notify.getData() != null ? ByteBufUtil.hexDump(notify.getData()) : null);
 288                         notifyTerminationReasonAndCloseWithoutMessage(notify.getErrorCode(), notify.getErrorSubcode());
 289                     } else if (msg instanceof Keepalive) {
 290                         // Keepalives are handled internally
 291                         LOG.trace("Received KeepAlive message.");
 292                         this.kaCounter++;
 293                         if (this.kaCounter >= 2) {
 294                             this.sync.kaReceived();
 295                         }
 296                     } else if (msg instanceof RouteRefresh) {
 297                         this.listener.onMessage(this, msg);
 298                     } else if (msg instanceof Update) {
 299                         this.listener.onMessage(this, msg);
 300                         this.sync.updReceived((Update) msg);
 301                     } else {
 302                         LOG.warn("Ignoring unhandled message: {}.", msg.getClass());
 303                     }
 304
 305                     this.sessionState.messageReceived(msg);
 306                 } catch (final BGPDocumentedException e) {
 307                     terminate(e);
 308                 }
 309             }
 310         }
 311     }
 312
 313     @Holding({"this.listener", "this"})
 314     private void notifyTerminationReasonAndCloseWithoutMessage(final BGPError error) {
 315         this.terminationReasonNotified = true;
 316         this.closeWithoutMessage();
 317         this.listener.onSessionTerminated(this, new BGPTerminationReason(error));
 318     }
 319
 320     @Holding({"this.listener", "this"})
 321     private void notifyTerminationReasonAndCloseWithoutMessage(final Uint8 errorCode, final Uint8 errorSubcode) {
 322         this.terminationReasonNotified = true;
 323         this.closeWithoutMessage();
 324         this.listener.onSessionTerminated(this, new BGPTerminationReason(BGPError.forValue(errorCode, errorSubcode)));
 325     }
 326
 327     void endOfInput() {
 328         // synchronize on listener and then on this object to ensure correct order of locking
 329         synchronized (this.listener) {
 330             synchronized (this) {
 331                 if (this.state == State.UP) {
 332                     LOG.info(END_OF_INPUT);
 333                     this.listener.onSessionDown(this, new IOException(END_OF_INPUT));
 334                 }
 335             }
 336         }
 337     }
 338
 339     @Holding("this")
 340     private ChannelFuture writeEpilogue(final ChannelFuture future, final Notification msg) {
 341         future.addListener((ChannelFutureListener) f -> {
 342             if (f.isSuccess()) {
 343                 LOG.trace("Message {} sent to socket {}", msg, this.channel);
 344             } else {
 345                 LOG.warn("Failed to send message {} to socket {}", msg, this.channel, f.cause());
 346             }
 347         });
 348         this.lastMessageSentAt = System.nanoTime();
 349         this.sessionState.messageSent(msg);
 350         return future;
 351     }
 352
 353     void flush() {
 354         this.channel.flush();
 355     }
 356
 357     @SuppressWarnings("checkstyle:illegalCatch")
 358     synchronized void write(final Notification msg) {
 359         try {
 360             writeEpilogue(this.channel.write(msg), msg);
 361         } catch (final Exception e) {
 362             LOG.warn("Message {} was not sent.", msg, e);
 363         }
 364     }
 365
 366     synchronized ChannelFuture writeAndFlush(final Notification msg) {
 367         if (this.channel.isWritable()) {
 368             return writeEpilogue(this.channel.writeAndFlush(msg), msg);
 369         }
 370         return this.channel.newFailedFuture(new NonWritableChannelException());
 371     }
 372
 373     @Override
 374     public synchronized void closeWithoutMessage() {
 375         if (this.state == State.IDLE) {
 376             return;
 377         }
 378         LOG.info("Closing session: {}", this);
 379         this.channel.close().addListener((ChannelFutureListener) future -> {
 380             if (future.isSuccess()) {
 381                 LOG.debug("Channel {} closed successfully", this.channel);
 382             } else {
 383                 LOG.warn("Channel {} failed to close", this.channel, future.cause());
 384             }
 385         });
 386
 387         this.state = State.IDLE;
 388         removePeerSession();
 389         this.sessionState.setSessionState(this.state);
 390     }
 391
 392     /**
 393      * Closes BGP session from the parent with given reason. A message needs to be sent, but parent doesn't have to be
 394      * modified, because he initiated the closing. (To prevent concurrent modification exception).
 395      *
 396      * @param cause BGPDocumentedException
 397      */
 398     @VisibleForTesting
 399     @Holding({"this.listener", "this"})
 400     void terminate(final BGPDocumentedException cause) {
 401         final BGPError error = cause.getError();
 402         final byte[] data = cause.getData();
 403         final NotifyBuilder builder = new NotifyBuilder().setErrorCode(error.getCode())
 404                 .setErrorSubcode(error.getSubcode());
 405         if (data != null && data.length != 0) {
 406             builder.setData(data);
 407         }
 408         writeAndFlush(builder.build());
 409         notifyTerminationReasonAndCloseWithoutMessage(error);
 410     }
 411
 412     private void removePeerSession() {
 413         if (this.peerRegistry != null) {
 414             this.peerRegistry.removePeerSession(StrictBGPPeerRegistry.getIpAddress(this.channel.remoteAddress()));
 415         }
 416     }
 417
 418     /**
 419      * If HoldTimer expires, the session ends. If a message (whichever) was received during this period, the HoldTimer
 420      * will be rescheduled by HOLD_TIMER_VALUE + the time that has passed from the start of the HoldTimer to the time at
 421      * which the message was received. If the session was closed by the time this method starts to execute (the session
 422      * state will become IDLE), then rescheduling won't occur.
 423      */
 424     private void handleHoldTimer() {
 425         // synchronize on listener and then on this object to ensure correct order of locking
 426         synchronized (this.listener) {
 427             synchronized (this) {
 428                 if (this.state == State.IDLE) {
 429                     return;
 430                 }
 431
 432                 final long ct = System.nanoTime();
 433                 final long nextHold = this.lastMessageReceivedAt + holdTimerNanos;
 434
 435                 if (ct >= nextHold) {
 436                     LOG.debug("HoldTimer expired. {}", new Date());
 437                     terminate(new BGPDocumentedException(BGPError.HOLD_TIMER_EXPIRED));
 438                 } else {
 439                     this.channel.eventLoop().schedule(this::handleHoldTimer, nextHold - ct, TimeUnit.NANOSECONDS);
 440                 }
 441             }
 442         }
 443     }
 444
 445     /**
 446      * If KeepAlive Timer expires, sends KeepAlive message. If a message (whichever) was send during this period, the
 447      * KeepAlive Timer will be rescheduled by KEEP_ALIVE_TIMER_VALUE + the time that has passed from the start of the
 448      * KeepAlive timer to the time at which the message was sent. If the session was closed by the time this method
 449      * starts to execute (the session state will become IDLE), that rescheduling won't occur.
 450      */
 451     private synchronized void handleKeepaliveTimer() {
 452         if (this.state == State.IDLE) {
 453             LOG.debug("Skipping keepalive on session idle {}", this);
 454             return;
 455         }
 456
 457         final long ct = System.nanoTime();
 458         final long nextKeepalive = this.lastMessageSentAt + keepAliveNanos;
 459         long nextNanos = nextKeepalive - ct;
 460
 461         if (nextNanos <= 0) {
 462             final ChannelFuture future = this.writeAndFlush(KEEP_ALIVE);
 463             LOG.debug("Enqueued session {} keepalive as {}", this, future);
 464             nextNanos = keepAliveNanos;
 465             if (LOG.isDebugEnabled()) {
 466                 future.addListener(compl -> LOG.debug("Session {} keepalive completed as {}", this, compl));
 467             }
 468         } else {
 469             LOG.debug("Skipping keepalive on session {}", this);
 470         }
 471
 472         LOG.debug("Scheduling next keepalive on {} in {} nanos", this, nextNanos);
 473         this.channel.eventLoop().schedule(this::handleKeepaliveTimer, nextNanos, TimeUnit.NANOSECONDS);
 474     }
 475
 476     @Override
 477     public final String toString() {
 478         return addToStringAttributes(MoreObjects.toStringHelper(this)).toString();
 479     }
 480
 481     protected ToStringHelper addToStringAttributes(final ToStringHelper toStringHelper) {
 482         toStringHelper.add("channel", this.channel);
 483         toStringHelper.add("state", this.getState());
 484         return toStringHelper;
 485     }
 486
 487     @Override
 488     public Set<BgpTableType> getAdvertisedTableTypes() {
 489         return this.tableTypes;
 490     }
 491
 492     @Override
 493     public List<AddressFamilies> getAdvertisedAddPathTableTypes() {
 494         return this.addPathTypes;
 495     }
 496
 497     @Override
 498     public GracefulRestartCapability getAdvertisedGracefulRestartCapability() {
 499         return this.gracefulCapability;
 500     }
 501
 502     @Override
 503     public LlGracefulRestartCapability getAdvertisedLlGracefulRestartCapability() {
 504         return this.llGracefulCapability;
 505     }
 506
 507     @VisibleForTesting
 508     @SuppressWarnings("checkstyle:illegalCatch")
 509     void sessionUp() {
 510         // synchronize on listener and then on this object to ensure correct order of locking
 511         synchronized (this.listener) {
 512             synchronized (this) {
 513                 this.state = State.UP;
 514                 try {
 515                     this.sessionState.setSessionState(this.state);
 516                     this.listener.onSessionUp(this);
 517                 } catch (final Exception e) {
 518                     handleException(e);
 519                     throw e;
 520                 }
 521             }
 522         }
 523     }
 524
 525     public synchronized State getState() {
 526         return this.state;
 527     }
 528
 529     @Override
 530     public final Ipv4Address getBgpId() {
 531         return this.bgpId;
 532     }
 533
 534     @Override
 535     public final AsNumber getAsNumber() {
 536         return this.asNumber;
 537     }
 538
 539     public ChannelOutputLimiter getLimiter() {
 540         return this.limiter;
 541     }
 542
 543     @Override
 544     public final void channelInactive(final ChannelHandlerContext ctx) throws Exception {
 545         LOG.debug("Channel {} inactive.", ctx.channel());
 546         endOfInput();
 547         super.channelInactive(ctx);
 548     }
 549
 550     @Override
 551     protected final void channelRead0(final ChannelHandlerContext ctx, final Notification msg) {
 552         LOG.trace("Message was received: {}", msg);
 553         this.handleMessage(msg);
 554     }
 555
 556     @Override
 557     public final void handlerAdded(final ChannelHandlerContext ctx) {
 558         this.sessionUp();
 559     }
 560
 561     @Override
 562     public void exceptionCaught(final ChannelHandlerContext ctx, final Throwable cause) {
 563         // synchronize on listener and then on this object to ensure correct order of locking
 564         synchronized (this.listener) {
 565             synchronized (this) {
 566                 handleException(cause);
 567             }
 568         }
 569     }
 570
 571     /**
 572      * Handle exception occurred in the BGP session. The session in error state should be closed
 573      * properly so that it can be restored later.
 574      */
 575     @Holding({"this.listener", "this"})
 576     @VisibleForTesting
 577     void handleException(final Throwable cause) {
 578         LOG.warn("BGP session encountered error", cause);
 579         final Throwable docCause = cause.getCause();
 580         terminate(docCause instanceof BGPDocumentedException
 581             ? (BGPDocumentedException) docCause : new BGPDocumentedException(BGPError.CEASE));
 582     }
 583
 584     @Override
 585     public BGPSessionState getBGPSessionState() {
 586         return this.sessionState;
 587     }
 588
 589     @Override
 590     public BGPTimersState getBGPTimersState() {
 591         return this.sessionState;
 592     }
 593
 594     @Override
 595     public BGPTransportState getBGPTransportState() {
 596         return this.sessionState;
 597     }
 598
 599     @Override
 600     public void registerMessagesCounter(final BGPMessagesListener bgpMessagesListener) {
 601         this.sessionState.registerMessagesCounter(bgpMessagesListener);
 602     }
 603
 604     @Override
 605     public <T extends PeerConstraint> void addDecoderConstraint(final Class<T> constraintClass, final T constraint) {
 606         this.channel.pipeline().get(BGPByteToMessageDecoder.class).addDecoderConstraint(constraintClass, constraint);
 607     }
 608
 609     @Override
 610     public ScheduledFuture<?> schedule(final Runnable command, final long delay, final TimeUnit unit) {
 611         return this.channel.eventLoop().schedule(command, delay, unit);
 612     }
 613 }