BUG-1949 Fix race condition in AsyncSshHandler

[controller.git] / opendaylight / netconf / netconf-netty-util / src / main / java / org / opendaylight / controller / netconf / nettyutil / handler / ssh / client / AsyncSshHanderReader.java

diff --git a/opendaylight/netconf/netconf-netty-util/src/main/java/org/opendaylight/controller/netconf/nettyutil/handler/ssh/client/AsyncSshHanderReader.java b/opendaylight/netconf/netconf-netty-util/src/main/java/org/opendaylight/controller/netconf/nettyutil/handler/ssh/client/AsyncSshHanderReader.java
new file mode 100644 (file)
index 0000000..73a24f2
--- /dev/null
+++ b/opendaylight/netconf/netconf-netty-util/src/main/java/org/opendaylight/controller/netconf/nettyutil/handler/ssh/client/AsyncSshHanderReader.java
@@ -0,0 +1,87 @@
+/*
+ * 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.controller.netconf.nettyutil.handler.ssh.client;
+
+import io.netty.buffer.Unpooled;
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.channel.ChannelOutboundHandler;
+import org.apache.sshd.common.future.SshFutureListener;
+import org.apache.sshd.common.io.IoInputStream;
+import org.apache.sshd.common.io.IoReadFuture;
+import org.apache.sshd.common.util.Buffer;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Listener on async input stream from SSH session.
+ * This listeners schedules reads in a loop until the session is closed or read fails.
+ */
+final class AsyncSshHanderReader implements SshFutureListener<IoReadFuture>, AutoCloseable {
+
+    private static final Logger logger = LoggerFactory.getLogger(AsyncSshHandler.class);
+
+    private static final int BUFFER_SIZE = 8192;
+
+    private final ChannelOutboundHandler asyncSshHandler;
+    private final ChannelHandlerContext ctx;
+
+    private IoInputStream asyncOut;
+    private Buffer buf;
+    private IoReadFuture currentReadFuture;
+
+    public AsyncSshHanderReader(final ChannelOutboundHandler asyncSshHandler, final ChannelHandlerContext ctx, final IoInputStream asyncOut) {
+        this.asyncSshHandler = asyncSshHandler;
+        this.ctx = ctx;
+        this.asyncOut = asyncOut;
+        buf = new Buffer(BUFFER_SIZE);
+        asyncOut.read(buf).addListener(this);
+    }
+
+    @Override
+    public synchronized void operationComplete(final IoReadFuture future) {
+        if(future.getException() != null) {
+            if(asyncOut.isClosed() || asyncOut.isClosing()) {
+                // Ssh dropped
+                logger.debug("Ssh session dropped on channel: {}", ctx.channel(), future.getException());
+            } else {
+                logger.warn("Exception while reading from SSH remote on channel {}", ctx.channel(), future.getException());
+            }
+            invokeDisconnect();
+            return;
+        }
+
+        if (future.getRead() > 0) {
+            ctx.fireChannelRead(Unpooled.wrappedBuffer(buf.array(), 0, future.getRead()));
+
+            // Schedule next read
+            buf = new Buffer(BUFFER_SIZE);
+            currentReadFuture = asyncOut.read(buf);
+            currentReadFuture.addListener(this);
+        }
+    }
+
+    private void invokeDisconnect() {
+        try {
+            asyncSshHandler.disconnect(ctx, ctx.newPromise());
+        } catch (final Exception e) {
+            // This should not happen
+            throw new IllegalStateException(e);
+        }
+    }
+
+    @Override
+    public synchronized void close() {
+        // Remove self as listener on close to prevent reading from closed input
+        if(currentReadFuture != null) {
+            currentReadFuture.removeListener(this);
+        }
+
+        asyncOut = null;
+    }
+}