transport/transport-ssh/src/main/java/org/opendaylight/netconf/transport/ssh/TransportServerSession.java

   1 /*
   2  * Copyright (c) 2023 PANTHEON.tech, s.r.o. 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.netconf.transport.ssh;
   9
  10 import static java.util.Objects.requireNonNull;
  11
  12 import com.google.common.util.concurrent.ListenableFuture;
  13 import com.google.common.util.concurrent.SettableFuture;
  14 import io.netty.channel.ChannelHandlerContext;
  15 import java.io.IOException;
  16 import java.lang.invoke.MethodHandles;
  17 import java.lang.invoke.VarHandle;
  18 import org.eclipse.jdt.annotation.Nullable;
  19 import org.opendaylight.netconf.shaded.sshd.common.io.IoSession;
  20 import org.opendaylight.netconf.shaded.sshd.server.session.ServerSessionImpl;
  21 import org.opendaylight.netconf.transport.api.TransportChannel;
  22
  23 /**
  24  * A {@link ServerSessionImpl}, bound to a backend Netty channel.
  25  */
  26 final class TransportServerSession extends ServerSessionImpl {
  27     private record State(String subsystem, TransportChannel underlay, SettableFuture<ChannelHandlerContext> future) {
  28         State {
  29             subsystem = requireNonNull(subsystem);
  30             underlay = requireNonNull(underlay);
  31             future = requireNonNull(future);
  32         }
  33     }
  34
  35     private static final VarHandle STATE;
  36
  37     static {
  38         try {
  39             STATE = MethodHandles.lookup().findVarHandle(TransportServerSession.class, "state", State.class);
  40         } catch (NoSuchFieldException | IllegalAccessException e) {
  41             throw new ExceptionInInitializerError(e);
  42         }
  43     }
  44
  45     @SuppressWarnings("unused")
  46     private volatile State state;
  47
  48     TransportServerSession(final TransportSshServer server, final IoSession ioSession) throws Exception {
  49         super(server, ioSession);
  50     }
  51
  52     ListenableFuture<ChannelHandlerContext> attachUnderlay(final String subsystem, final TransportChannel underlay) {
  53         final var newState = new State(subsystem, underlay, SettableFuture.create());
  54         final var witness = STATE.compareAndExchange(this, null, newState);
  55         if (witness != null) {
  56             throw new IllegalStateException("Already set up for " + witness);
  57         }
  58         return newState.future;
  59     }
  60
  61     @Nullable TransportServerSubsystem openSubsystem(final String subsystem) {
  62         final var local = (State) STATE.getAndSet(this, null);
  63         if (local != null) {
  64             if (subsystem.equals(local.subsystem)) {
  65                 return new TransportServerSubsystem(subsystem, local.underlay, local.future);
  66             }
  67             local.future.setException(new IOException("Mismatched subsystem " + subsystem));
  68         }
  69         return null;
  70     }
  71 }