2 * Copyright (c) 2014 Cisco Systems, Inc. and others. All rights reserved.
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
9 package org.opendaylight.netconf.nettyutil.handler.ssh.client;
11 import com.google.common.base.Preconditions;
12 import io.netty.buffer.ByteBuf;
13 import io.netty.channel.ChannelHandlerContext;
14 import io.netty.channel.ChannelPromise;
15 import java.io.IOException;
16 import java.nio.charset.StandardCharsets;
17 import java.util.Deque;
18 import java.util.LinkedList;
19 import java.util.Queue;
20 import org.apache.sshd.common.io.IoOutputStream;
21 import org.apache.sshd.common.io.WritePendingException;
22 import org.apache.sshd.common.util.buffer.Buffer;
23 import org.apache.sshd.common.util.buffer.ByteArrayBuffer;
24 import org.slf4j.Logger;
25 import org.slf4j.LoggerFactory;
28 * Async Ssh writer. Takes messages(byte arrays) and sends them encrypted to remote server.
29 * Also handles pending writes by caching requests until pending state is over.
31 public final class AsyncSshHandlerWriter implements AutoCloseable {
33 private static final Logger LOG = LoggerFactory
34 .getLogger(AsyncSshHandlerWriter.class);
36 // public static final int MAX_PENDING_WRITES = 1000;
37 // TODO implement Limiting mechanism for pending writes
38 // But there is a possible issue with limiting:
39 // 1. What to do when queue is full ? Immediate Fail for every request ?
40 // 2. At this level we might be dealing with Chunks of messages(not whole messages)
41 // and unexpected behavior might occur when we send/queue 1 chunk and fail the other chunks
43 private final Object asyncInLock = new Object();
44 private volatile IoOutputStream asyncIn;
46 // Order has to be preserved for queued writes
47 private final Deque<PendingWriteRequest> pending = new LinkedList<>();
49 public AsyncSshHandlerWriter(final IoOutputStream asyncIn) {
50 this.asyncIn = asyncIn;
53 public void write(final ChannelHandlerContext ctx,
54 final Object msg, final ChannelPromise promise) {
55 if (asyncIn == null) {
56 promise.setFailure(new IllegalStateException("Channel closed"));
59 // synchronized block due to deadlock that happens on ssh window resize
60 // writes and pending writes would lock the underlyinch channel session
61 // window resize write would try to write the message on an already locked channelSession
62 // while the pending write was in progress from the write callback
63 synchronized (asyncInLock) {
64 // TODO check for isClosed, isClosing might be performed by mina SSH internally and is not required here
65 // If we are closed/closing, set immediate fail
66 if (asyncIn.isClosed() || asyncIn.isClosing()) {
67 promise.setFailure(new IllegalStateException("Channel closed"));
69 final ByteBuf byteBufMsg = (ByteBuf) msg;
70 if (!pending.isEmpty()) {
71 queueRequest(ctx, byteBufMsg, promise);
75 writeWithPendingDetection(ctx, promise, byteBufMsg, false);
80 //sending message with pending
81 //if resending message not succesfull, then attribute wasPending is true
82 private void writeWithPendingDetection(final ChannelHandlerContext ctx, final ChannelPromise promise,
83 final ByteBuf byteBufMsg, final boolean wasPending) {
86 if (LOG.isTraceEnabled()) {
87 LOG.trace("Writing request on channel: {}, message: {}", ctx.channel(), byteBufToString(byteBufMsg));
89 asyncIn.writePacket(toBuffer(byteBufMsg)).addListener(future -> {
90 // synchronized block due to deadlock that happens on ssh window resize
91 // writes and pending writes would lock the underlyinch channel session
92 // window resize write would try to write the message on an already locked channelSession,
93 // while the pending write was in progress from the write callback
94 synchronized (asyncInLock) {
95 if (LOG.isTraceEnabled()) {
97 "Ssh write request finished on channel: {} with result: {}: and ex:{}, message: {}",
98 ctx.channel(), future.isWritten(), future.getException(), byteBufToString(byteBufMsg));
101 // Notify success or failure
102 if (future.isWritten()) {
103 promise.setSuccess();
105 LOG.warn("Ssh write request failed on channel: {} for message: {}", ctx.channel(),
106 byteBufToString(byteBufMsg), future.getException());
107 promise.setFailure(future.getException());
110 //rescheduling message from queue after successfully sent
112 byteBufMsg.resetReaderIndex();
116 // Not needed anymore, release
117 byteBufMsg.release();
120 // Check pending queue and schedule next
121 // At this time we are guaranteed that we are not in pending state anymore
122 // so the next request should succeed
126 } catch (final IOException | WritePendingException e) {
128 queueRequest(ctx, byteBufMsg, promise);
133 private void writePendingIfAny() {
134 synchronized (asyncInLock) {
135 if (pending.peek() == null) {
139 final PendingWriteRequest pendingWrite = pending.peek();
140 final ByteBuf msg = pendingWrite.msg;
141 if (LOG.isTraceEnabled()) {
142 LOG.trace("Writing pending request on channel: {}, message: {}",
143 pendingWrite.ctx.channel(), byteBufToString(msg));
146 writeWithPendingDetection(pendingWrite.ctx, pendingWrite.promise, msg, true);
150 public static String byteBufToString(final ByteBuf msg) {
151 final String s = msg.toString(StandardCharsets.UTF_8);
152 msg.resetReaderIndex();
156 private void queueRequest(final ChannelHandlerContext ctx, final ByteBuf msg, final ChannelPromise promise) {
158 LOG.debug("Write pending on channel: {}, queueing, current queue size: {}", ctx.channel(), pending.size());
159 if (LOG.isTraceEnabled()) {
160 LOG.trace("Queueing request due to pending: {}", byteBufToString(msg));
162 new PendingWriteRequest(ctx, msg, promise).pend(pending);
163 // } catch (final Exception ex) {
164 // LOG.warn("Unable to queue write request on channel: {}. Setting fail for the request: {}",
165 // ctx.channel(), ex, byteBufToString(msg));
167 // promise.setFailure(ex);
172 public void close() {
176 private static Buffer toBuffer(final ByteBuf msg) {
177 // TODO Buffer vs ByteBuf translate, Can we handle that better ?
178 msg.resetReaderIndex();
179 final byte[] temp = new byte[msg.readableBytes()];
180 msg.readBytes(temp, 0, msg.readableBytes());
181 return new ByteArrayBuffer(temp);
184 private static final class PendingWriteRequest {
185 private final ChannelHandlerContext ctx;
186 private final ByteBuf msg;
187 private final ChannelPromise promise;
189 PendingWriteRequest(final ChannelHandlerContext ctx, final ByteBuf msg, final ChannelPromise promise) {
191 // Reset reader index, last write (failed) attempt moved index to the end
192 msg.resetReaderIndex();
194 this.promise = promise;
197 public void pend(final Queue<PendingWriteRequest> pending) {
198 // Preconditions.checkState(pending.size() < MAX_PENDING_WRITES,
199 // "Too much pending writes(%s) on channel: %s, remote window is not getting read or is too small",
200 // pending.size(), ctx.channel());
201 Preconditions.checkState(pending.offer(this),
202 "Cannot pend another request write (pending count: %s) on channel: %s", pending.size(), ctx.channel());