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/*
* 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:
*
* http://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.concurrent.ScheduledFuture;
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;
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 ScheduledFuture 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();
}
}
}
