io.netty.handler.proxy.ProxyHandler Maven / Gradle / Ivy
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This artifact provides a single jar that contains all classes required to use remote EJB and JMS, including
all dependencies. It is intended for use by those not using maven, maven users should just import the EJB and
JMS BOM's instead (shaded JAR's cause lots of problems with maven, as it is very easy to inadvertently end up
with different versions on classes on the class path).
/*
* Copyright 2014 The Netty Project
*
* The Netty Project licenses this file to you under the Apache License,
* version 2.0 (the "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at:
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations
* under the License.
*/
package io.netty.handler.proxy;
import io.netty.channel.Channel;
import io.netty.channel.ChannelDuplexHandler;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelPromise;
import io.netty.channel.PendingWriteQueue;
import io.netty.util.ReferenceCountUtil;
import io.netty.util.concurrent.DefaultPromise;
import io.netty.util.concurrent.EventExecutor;
import io.netty.util.concurrent.Future;
import io.netty.util.internal.ObjectUtil;
import io.netty.util.internal.logging.InternalLogger;
import io.netty.util.internal.logging.InternalLoggerFactory;
import java.net.SocketAddress;
import java.nio.channels.ConnectionPendingException;
import java.util.concurrent.TimeUnit;
/**
* A common abstraction for protocols that establish blind forwarding proxy tunnels.
*/
public abstract class ProxyHandler extends ChannelDuplexHandler {
private static final InternalLogger logger = InternalLoggerFactory.getInstance(ProxyHandler.class);
/**
* The default connect timeout: 10 seconds.
*/
private static final long DEFAULT_CONNECT_TIMEOUT_MILLIS = 10000;
/**
* A string that signifies 'no authentication' or 'anonymous'.
*/
static final String AUTH_NONE = "none";
private final SocketAddress proxyAddress;
private volatile SocketAddress destinationAddress;
private volatile long connectTimeoutMillis = DEFAULT_CONNECT_TIMEOUT_MILLIS;
private volatile ChannelHandlerContext ctx;
private PendingWriteQueue pendingWrites;
private boolean finished;
private boolean suppressChannelReadComplete;
private boolean flushedPrematurely;
private final LazyChannelPromise connectPromise = new LazyChannelPromise();
private Future connectTimeoutFuture;
private final ChannelFutureListener writeListener = new ChannelFutureListener() {
@Override
public void operationComplete(ChannelFuture future) throws Exception {
if (!future.isSuccess()) {
setConnectFailure(future.cause());
}
}
};
protected ProxyHandler(SocketAddress proxyAddress) {
this.proxyAddress = ObjectUtil.checkNotNull(proxyAddress, "proxyAddress");
}
/**
* Returns the name of the proxy protocol in use.
*/
public abstract String protocol();
/**
* Returns the name of the authentication scheme in use.
*/
public abstract String authScheme();
/**
* Returns the address of the proxy server.
*/
@SuppressWarnings("unchecked")
public final T proxyAddress() {
return (T) proxyAddress;
}
/**
* Returns the address of the destination to connect to via the proxy server.
*/
@SuppressWarnings("unchecked")
public final T destinationAddress() {
return (T) destinationAddress;
}
/**
* Returns {@code true} if and only if the connection to the destination has been established successfully.
*/
public final boolean isConnected() {
return connectPromise.isSuccess();
}
/**
* Returns a {@link Future} that is notified when the connection to the destination has been established
* or the connection attempt has failed.
*/
public final Future connectFuture() {
return connectPromise;
}
/**
* Returns the connect timeout in millis. If the connection attempt to the destination does not finish within
* the timeout, the connection attempt will be failed.
*/
public final long connectTimeoutMillis() {
return connectTimeoutMillis;
}
/**
* Sets the connect timeout in millis. If the connection attempt to the destination does not finish within
* the timeout, the connection attempt will be failed.
*/
public final void setConnectTimeoutMillis(long connectTimeoutMillis) {
if (connectTimeoutMillis <= 0) {
connectTimeoutMillis = 0;
}
this.connectTimeoutMillis = connectTimeoutMillis;
}
@Override
public final void handlerAdded(ChannelHandlerContext ctx) throws Exception {
this.ctx = ctx;
addCodec(ctx);
if (ctx.channel().isActive()) {
// channelActive() event has been fired already, which means this.channelActive() will
// not be invoked. We have to initialize here instead.
sendInitialMessage(ctx);
} else {
// channelActive() event has not been fired yet. this.channelOpen() will be invoked
// and initialization will occur there.
}
}
/**
* Adds the codec handlers required to communicate with the proxy server.
*/
protected abstract void addCodec(ChannelHandlerContext ctx) throws Exception;
/**
* Removes the encoders added in {@link #addCodec(ChannelHandlerContext)}.
*/
protected abstract void removeEncoder(ChannelHandlerContext ctx) throws Exception;
/**
* Removes the decoders added in {@link #addCodec(ChannelHandlerContext)}.
*/
protected abstract void removeDecoder(ChannelHandlerContext ctx) throws Exception;
@Override
public final void connect(
ChannelHandlerContext ctx, SocketAddress remoteAddress, SocketAddress localAddress,
ChannelPromise promise) throws Exception {
if (destinationAddress != null) {
promise.setFailure(new ConnectionPendingException());
return;
}
destinationAddress = remoteAddress;
ctx.connect(proxyAddress, localAddress, promise);
}
@Override
public final void channelActive(ChannelHandlerContext ctx) throws Exception {
sendInitialMessage(ctx);
ctx.fireChannelActive();
}
/**
* Sends the initial message to be sent to the proxy server. This method also starts a timeout task which marks
* the {@link #connectPromise} as failure if the connection attempt does not success within the timeout.
*/
private void sendInitialMessage(final ChannelHandlerContext ctx) throws Exception {
final long connectTimeoutMillis = this.connectTimeoutMillis;
if (connectTimeoutMillis > 0) {
connectTimeoutFuture = ctx.executor().schedule(new Runnable() {
@Override
public void run() {
if (!connectPromise.isDone()) {
setConnectFailure(new ProxyConnectException(exceptionMessage("timeout")));
}
}
}, connectTimeoutMillis, TimeUnit.MILLISECONDS);
}
final Object initialMessage = newInitialMessage(ctx);
if (initialMessage != null) {
sendToProxyServer(initialMessage);
}
readIfNeeded(ctx);
}
/**
* Returns a new message that is sent at first time when the connection to the proxy server has been established.
*
* @return the initial message, or {@code null} if the proxy server is expected to send the first message instead
*/
protected abstract Object newInitialMessage(ChannelHandlerContext ctx) throws Exception;
/**
* Sends the specified message to the proxy server. Use this method to send a response to the proxy server in
* {@link #handleResponse(ChannelHandlerContext, Object)}.
*/
protected final void sendToProxyServer(Object msg) {
ctx.writeAndFlush(msg).addListener(writeListener);
}
@Override
public final void channelInactive(ChannelHandlerContext ctx) throws Exception {
if (finished) {
ctx.fireChannelInactive();
} else {
// Disconnected before connected to the destination.
setConnectFailure(new ProxyConnectException(exceptionMessage("disconnected")));
}
}
@Override
public final void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
if (finished) {
ctx.fireExceptionCaught(cause);
} else {
// Exception was raised before the connection attempt is finished.
setConnectFailure(cause);
}
}
@Override
public final void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
if (finished) {
// Received a message after the connection has been established; pass through.
suppressChannelReadComplete = false;
ctx.fireChannelRead(msg);
} else {
suppressChannelReadComplete = true;
Throwable cause = null;
try {
boolean done = handleResponse(ctx, msg);
if (done) {
setConnectSuccess();
}
} catch (Throwable t) {
cause = t;
} finally {
ReferenceCountUtil.release(msg);
if (cause != null) {
setConnectFailure(cause);
}
}
}
}
/**
* Handles the message received from the proxy server.
*
* @return {@code true} if the connection to the destination has been established,
* {@code false} if the connection to the destination has not been established and more messages are
* expected from the proxy server
*/
protected abstract boolean handleResponse(ChannelHandlerContext ctx, Object response) throws Exception;
private void setConnectSuccess() {
finished = true;
cancelConnectTimeoutFuture();
if (!connectPromise.isDone()) {
boolean removedCodec = true;
removedCodec &= safeRemoveEncoder();
ctx.fireUserEventTriggered(
new ProxyConnectionEvent(protocol(), authScheme(), proxyAddress, destinationAddress));
removedCodec &= safeRemoveDecoder();
if (removedCodec) {
writePendingWrites();
if (flushedPrematurely) {
ctx.flush();
}
connectPromise.trySuccess(ctx.channel());
} else {
// We are at inconsistent state because we failed to remove all codec handlers.
Exception cause = new ProxyConnectException(
"failed to remove all codec handlers added by the proxy handler; bug?");
failPendingWritesAndClose(cause);
}
}
}
private boolean safeRemoveDecoder() {
try {
removeDecoder(ctx);
return true;
} catch (Exception e) {
logger.warn("Failed to remove proxy decoders:", e);
}
return false;
}
private boolean safeRemoveEncoder() {
try {
removeEncoder(ctx);
return true;
} catch (Exception e) {
logger.warn("Failed to remove proxy encoders:", e);
}
return false;
}
private void setConnectFailure(Throwable cause) {
finished = true;
cancelConnectTimeoutFuture();
if (!connectPromise.isDone()) {
if (!(cause instanceof ProxyConnectException)) {
cause = new ProxyConnectException(
exceptionMessage(cause.toString()), cause);
}
safeRemoveDecoder();
safeRemoveEncoder();
failPendingWritesAndClose(cause);
}
}
private void failPendingWritesAndClose(Throwable cause) {
failPendingWrites(cause);
connectPromise.tryFailure(cause);
ctx.fireExceptionCaught(cause);
ctx.close();
}
private void cancelConnectTimeoutFuture() {
if (connectTimeoutFuture != null) {
connectTimeoutFuture.cancel(false);
connectTimeoutFuture = null;
}
}
/**
* Decorates the specified exception message with the common information such as the current protocol,
* authentication scheme, proxy address, and destination address.
*/
protected final String exceptionMessage(String msg) {
if (msg == null) {
msg = "";
}
StringBuilder buf = new StringBuilder(128 + msg.length())
.append(protocol())
.append(", ")
.append(authScheme())
.append(", ")
.append(proxyAddress)
.append(" => ")
.append(destinationAddress);
if (!msg.isEmpty()) {
buf.append(", ").append(msg);
}
return buf.toString();
}
@Override
public final void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
if (suppressChannelReadComplete) {
suppressChannelReadComplete = false;
readIfNeeded(ctx);
} else {
ctx.fireChannelReadComplete();
}
}
@Override
public final void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) throws Exception {
if (finished) {
writePendingWrites();
ctx.write(msg, promise);
} else {
addPendingWrite(ctx, msg, promise);
}
}
@Override
public final void flush(ChannelHandlerContext ctx) throws Exception {
if (finished) {
writePendingWrites();
ctx.flush();
} else {
flushedPrematurely = true;
}
}
private static void readIfNeeded(ChannelHandlerContext ctx) {
if (!ctx.channel().config().isAutoRead()) {
ctx.read();
}
}
private void writePendingWrites() {
if (pendingWrites != null) {
pendingWrites.removeAndWriteAll();
pendingWrites = null;
}
}
private void failPendingWrites(Throwable cause) {
if (pendingWrites != null) {
pendingWrites.removeAndFailAll(cause);
pendingWrites = null;
}
}
private void addPendingWrite(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) {
PendingWriteQueue pendingWrites = this.pendingWrites;
if (pendingWrites == null) {
this.pendingWrites = pendingWrites = new PendingWriteQueue(ctx);
}
pendingWrites.add(msg, promise);
}
private final class LazyChannelPromise extends DefaultPromise {
@Override
protected EventExecutor executor() {
if (ctx == null) {
throw new IllegalStateException();
}
return ctx.executor();
}
}
}