Java tutorial
/* * Copyright (c) 2014 Cisco Systems, Inc. and others. All rights reserved. * * This program and the accompanying materials are made available under the * terms of the Eclipse Public License v1.0 which accompanies this distribution, * and is available at http://www.eclipse.org/legal/epl-v10.html */ package org.opendaylight.netconf.nettyutil.handler.ssh.client; import com.google.common.base.Preconditions; import io.netty.buffer.ByteBuf; import io.netty.channel.ChannelHandlerContext; import io.netty.channel.ChannelOutboundHandlerAdapter; import io.netty.channel.ChannelPromise; import io.netty.util.concurrent.Future; import io.netty.util.concurrent.GenericFutureListener; import java.io.IOException; import java.net.SocketAddress; import java.util.HashMap; import java.util.Map; import org.apache.sshd.ClientChannel; import org.apache.sshd.ClientSession; import org.apache.sshd.SshClient; import org.apache.sshd.client.future.AuthFuture; import org.apache.sshd.client.future.ConnectFuture; import org.apache.sshd.client.future.OpenFuture; import org.apache.sshd.common.future.CloseFuture; import org.apache.sshd.common.future.SshFutureListener; import org.opendaylight.netconf.nettyutil.handler.ssh.authentication.AuthenticationHandler; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /** * Netty SSH handler class. Acts as interface between Netty and SSH library. */ public class AsyncSshHandler extends ChannelOutboundHandlerAdapter { private static final Logger LOG = LoggerFactory.getLogger(AsyncSshHandler.class); public static final String SUBSYSTEM = "netconf"; public static final int SSH_DEFAULT_NIO_WORKERS = 8; // Disable default timeouts from mina sshd private static final long DEFAULT_TIMEOUT = -1L; public static final SshClient DEFAULT_CLIENT; static { final Map<String, String> props = new HashMap<>(); props.put(SshClient.AUTH_TIMEOUT, Long.toString(DEFAULT_TIMEOUT)); props.put(SshClient.IDLE_TIMEOUT, Long.toString(DEFAULT_TIMEOUT)); final SshClient c = SshClient.setUpDefaultClient(); c.setProperties(props); // TODO make configurable, or somehow reuse netty threadpool c.setNioWorkers(SSH_DEFAULT_NIO_WORKERS); c.start(); DEFAULT_CLIENT = c; } private final AuthenticationHandler authenticationHandler; private final SshClient sshClient; private Future<?> negotiationFuture; private AsyncSshHandlerReader sshReadAsyncListener; private AsyncSshHandlerWriter sshWriteAsyncHandler; private ClientChannel channel; private ClientSession session; private ChannelPromise connectPromise; private GenericFutureListener negotiationFutureListener; public AsyncSshHandler(final AuthenticationHandler authenticationHandler, final SshClient sshClient, final Future<?> negotiationFuture) throws IOException { this(authenticationHandler, sshClient); this.negotiationFuture = negotiationFuture; } /** * * @param authenticationHandler * @param sshClient started SshClient * @throws IOException */ public AsyncSshHandler(final AuthenticationHandler authenticationHandler, final SshClient sshClient) throws IOException { this.authenticationHandler = Preconditions.checkNotNull(authenticationHandler); this.sshClient = Preconditions.checkNotNull(sshClient); } public static AsyncSshHandler createForNetconfSubsystem(final AuthenticationHandler authenticationHandler) throws IOException { return new AsyncSshHandler(authenticationHandler, DEFAULT_CLIENT); } /** * * Create AsyncSshHandler for netconf subsystem. Negotiation future has to be set to success after successful netconf * negotiation. * * @param authenticationHandler * @param negotiationFuture * @return * @throws IOException */ public static AsyncSshHandler createForNetconfSubsystem(final AuthenticationHandler authenticationHandler, final Future<?> negotiationFuture) throws IOException { return new AsyncSshHandler(authenticationHandler, DEFAULT_CLIENT, negotiationFuture); } private void startSsh(final ChannelHandlerContext ctx, final SocketAddress address) { LOG.debug("Starting SSH to {} on channel: {}", address, ctx.channel()); final ConnectFuture sshConnectionFuture = sshClient.connect(authenticationHandler.getUsername(), address); sshConnectionFuture.addListener(new SshFutureListener<ConnectFuture>() { @Override public void operationComplete(final ConnectFuture future) { if (future.isConnected()) { handleSshSessionCreated(future, ctx); } else { handleSshSetupFailure(ctx, future.getException()); } } }); } private synchronized void handleSshSessionCreated(final ConnectFuture future, final ChannelHandlerContext ctx) { try { LOG.trace("SSH session created on channel: {}", ctx.channel()); session = future.getSession(); final AuthFuture authenticateFuture = authenticationHandler.authenticate(session); authenticateFuture.addListener(new SshFutureListener<AuthFuture>() { @Override public void operationComplete(final AuthFuture future) { if (future.isSuccess()) { handleSshAuthenticated(session, ctx); } else { // Exception does not have to be set in the future, add simple exception in such case final Throwable exception = future.getException() == null ? new IllegalStateException("Authentication failed") : future.getException(); handleSshSetupFailure(ctx, exception); } } }); } catch (final IOException e) { handleSshSetupFailure(ctx, e); } } private synchronized void handleSshAuthenticated(final ClientSession session, final ChannelHandlerContext ctx) { try { LOG.debug("SSH session authenticated on channel: {}, server version: {}", ctx.channel(), session.getServerVersion()); channel = session.createSubsystemChannel(SUBSYSTEM); channel.setStreaming(ClientChannel.Streaming.Async); channel.open().addListener(new SshFutureListener<OpenFuture>() { @Override public void operationComplete(final OpenFuture future) { if (future.isOpened()) { handleSshChanelOpened(ctx); } else { handleSshSetupFailure(ctx, future.getException()); } } }); } catch (final IOException e) { handleSshSetupFailure(ctx, e); } } private synchronized void handleSshChanelOpened(final ChannelHandlerContext ctx) { LOG.trace("SSH subsystem channel opened successfully on channel: {}", ctx.channel()); if (negotiationFuture == null) { connectPromise.setSuccess(); } // TODO we should also read from error stream and at least log from that sshReadAsyncListener = new AsyncSshHandlerReader(new AutoCloseable() { @Override public void close() throws Exception { AsyncSshHandler.this.disconnect(ctx, ctx.newPromise()); } }, new AsyncSshHandlerReader.ReadMsgHandler() { @Override public void onMessageRead(final ByteBuf msg) { ctx.fireChannelRead(msg); } }, channel.toString(), channel.getAsyncOut()); // if readAsyncListener receives immediate close, it will close this handler and closing this handler sets channel variable to null if (channel != null) { sshWriteAsyncHandler = new AsyncSshHandlerWriter(channel.getAsyncIn()); ctx.fireChannelActive(); } } private synchronized void handleSshSetupFailure(final ChannelHandlerContext ctx, final Throwable e) { LOG.warn("Unable to setup SSH connection on channel: {}", ctx.channel(), e); // If the promise is not yet done, we have failed with initial connect and set connectPromise to failure if (!connectPromise.isDone()) { connectPromise.setFailure(e); } disconnect(ctx, ctx.newPromise()); } @Override public synchronized void write(final ChannelHandlerContext ctx, final Object msg, final ChannelPromise promise) { sshWriteAsyncHandler.write(ctx, msg, promise); } @Override public synchronized void connect(final ChannelHandlerContext ctx, final SocketAddress remoteAddress, final SocketAddress localAddress, final ChannelPromise promise) throws Exception { LOG.debug("SSH session connecting on channel {}. promise: {} ", ctx.channel(), connectPromise); this.connectPromise = promise; if (negotiationFuture != null) { negotiationFutureListener = new GenericFutureListener<Future<?>>() { @Override public void operationComplete(final Future<?> future) { if (future.isSuccess()) { connectPromise.setSuccess(); } } }; //complete connection promise with netconf negotiation future negotiationFuture.addListener(negotiationFutureListener); } startSsh(ctx, remoteAddress); } @Override public void close(final ChannelHandlerContext ctx, final ChannelPromise promise) throws Exception { disconnect(ctx, promise); } @Override public synchronized void disconnect(final ChannelHandlerContext ctx, final ChannelPromise promise) { LOG.trace("Closing SSH session on channel: {} with connect promise in state: {}", ctx.channel(), connectPromise); // If we have already succeeded and the session was dropped after, we need to fire inactive to notify reconnect logic if (connectPromise.isSuccess()) { ctx.fireChannelInactive(); } if (sshWriteAsyncHandler != null) { sshWriteAsyncHandler.close(); } if (sshReadAsyncListener != null) { sshReadAsyncListener.close(); } //If connection promise is not already set, it means negotiation failed //we must set connection promise to failure if (!connectPromise.isDone()) { connectPromise.setFailure(new IllegalStateException("Negotiation failed")); } //Remove listener from negotiation future, we don't want notifications //from negotiation anymore if (negotiationFuture != null) { negotiationFuture.removeListener(negotiationFutureListener); } if (session != null && !session.isClosed() && !session.isClosing()) { session.close(false).addListener(new SshFutureListener<CloseFuture>() { @Override public void operationComplete(final CloseFuture future) { if (future.isClosed() == false) { session.close(true); } session = null; } }); } // Super disconnect is necessary in this case since we are using NioSocketChannel and it needs to cleanup its resources // e.g. Socket that it tries to open in its constructor (https://bugs.opendaylight.org/show_bug.cgi?id=2430) // TODO better solution would be to implement custom ChannelFactory + Channel that will use mina SSH lib internally: port this to custom channel implementation try { // Disconnect has to be closed after inactive channel event was fired, because it interferes with it super.disconnect(ctx, ctx.newPromise()); } catch (final Exception e) { LOG.warn("Unable to cleanup all resources for channel: {}. Ignoring.", ctx.channel(), e); } channel = null; promise.setSuccess(); LOG.debug("SSH session closed on channel: {}", ctx.channel()); } }