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 edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
  15 import io.netty.channel.ChannelHandlerContext;
  16 import java.io.IOException;
  17 import java.lang.invoke.MethodHandles;
  18 import java.lang.invoke.VarHandle;
  19 import org.eclipse.jdt.annotation.Nullable;
  20 import org.opendaylight.netconf.shaded.sshd.common.io.IoSession;
  21 import org.opendaylight.netconf.shaded.sshd.server.session.ServerSessionImpl;
  22 import org.opendaylight.netconf.transport.api.TransportChannel;
  23
  24 /**
  25  * A {@link ServerSessionImpl}, bound to a backend Netty channel.
  26  */
  27 final class TransportServerSession extends ServerSessionImpl {
  28     private record State(String subsystem, TransportChannel underlay, SettableFuture<ChannelHandlerContext> future) {
  29         State {
  30             subsystem = requireNonNull(subsystem);
  31             underlay = requireNonNull(underlay);
  32             future = requireNonNull(future);
  33         }
  34     }
  35
  36     private static final VarHandle STATE;
  37
  38     static {
  39         try {
  40             STATE = MethodHandles.lookup().findVarHandle(TransportServerSession.class, "state", State.class);
  41         } catch (NoSuchFieldException | IllegalAccessException e) {
  42             throw new ExceptionInInitializerError(e);
  43         }
  44     }
  45
  46     @SuppressWarnings("unused")
  47     @SuppressFBWarnings(value = "UUF_UNUSED_FIELD", justification = "https://github.com/spotbugs/spotbugs/issues/2749")
  48     private volatile State state;
  49
  50     TransportServerSession(final TransportSshServer server, final IoSession ioSession) throws Exception {
  51         super(server, ioSession);
  52     }
  53
  54     ListenableFuture<ChannelHandlerContext> attachUnderlay(final String subsystem, final TransportChannel underlay) {
  55         final var newState = new State(subsystem, underlay, SettableFuture.create());
  56         final var witness = STATE.compareAndExchange(this, null, newState);
  57         if (witness != null) {
  58             throw new IllegalStateException("Already set up for " + witness);
  59         }
  60         return newState.future;
  61     }
  62
  63     @Nullable TransportServerSubsystem openSubsystem(final String subsystem) {
  64         final var local = (State) STATE.getAndSet(this, null);
  65         if (local != null) {
  66             if (subsystem.equals(local.subsystem)) {
  67                 return new TransportServerSubsystem(subsystem, local.underlay, local.future);
  68             }
  69             local.future.setException(new IOException("Mismatched subsystem " + subsystem));
  70         }
  71         return null;
  72     }
  73 }