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The Netty project is an effort to provide an asynchronous event-driven
network application framework and tools for rapid development of
maintainable high performance and high scalability protocol servers and
clients. In other words, Netty is a NIO client server framework which
enables quick and easy development of network applications such as protocol
servers and clients. It greatly simplifies and streamlines network
programming such as TCP and UDP socket server.
/*
* Copyright 2012 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 org.jboss.netty.handler.codec.http;
import java.util.Queue;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.atomic.AtomicLong;
import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.channel.Channel;
import org.jboss.netty.channel.ChannelDownstreamHandler;
import org.jboss.netty.channel.ChannelEvent;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.ChannelStateEvent;
import org.jboss.netty.channel.ChannelUpstreamHandler;
import org.jboss.netty.handler.codec.PrematureChannelClosureException;
/**
* A combination of {@link HttpRequestEncoder} and {@link HttpResponseDecoder}
* which enables easier client side HTTP implementation. {@link HttpClientCodec}
* provides additional state management for HEAD and CONNECT
* requests, which {@link HttpResponseDecoder} lacks. Please refer to
* {@link HttpResponseDecoder} to learn what additional state management needs
* to be done for HEAD and CONNECT and why
* {@link HttpResponseDecoder} can not handle it by itself.
*
* If the {@link Channel} gets closed and there are requests missing for a response
* a {@link PrematureChannelClosureException} is thrown.
*
* @see HttpServerCodec
*
* @apiviz.has org.jboss.netty.handler.codec.http.HttpResponseDecoder
* @apiviz.has org.jboss.netty.handler.codec.http.HttpRequestEncoder
*/
public class HttpClientCodec implements ChannelUpstreamHandler,
ChannelDownstreamHandler {
/** A queue that is used for correlating a request and a response. */
final Queue queue = new ConcurrentLinkedQueue();
/** If true, decoding stops (i.e. pass-through) */
volatile boolean done;
private final HttpRequestEncoder encoder = new Encoder();
private final HttpResponseDecoder decoder;
private final AtomicLong requestResponseCounter = new AtomicLong(0);
private final boolean failOnMissingResponse;
/**
* Creates a new instance with the default decoder options
* ({@code maxInitialLineLength (4096}}, {@code maxHeaderSize (8192)}, and
* {@code maxChunkSize (8192)}).
*
*/
public HttpClientCodec() {
this(4096, 8192, 8192, false);
}
/**
* Creates a new instance with the specified decoder options.
*/
public HttpClientCodec(
int maxInitialLineLength, int maxHeaderSize, int maxChunkSize) {
this(maxInitialLineLength, maxHeaderSize, maxChunkSize, false);
}
/**
* Creates a new instance with the specified decoder options.
*/
public HttpClientCodec(
int maxInitialLineLength, int maxHeaderSize, int maxChunkSize, boolean failOnMissingResponse) {
decoder = new Decoder(maxInitialLineLength, maxHeaderSize, maxChunkSize);
this.failOnMissingResponse = failOnMissingResponse;
}
public void handleUpstream(ChannelHandlerContext ctx, ChannelEvent e)
throws Exception {
decoder.handleUpstream(ctx, e);
}
public void handleDownstream(ChannelHandlerContext ctx, ChannelEvent e)
throws Exception {
encoder.handleDownstream(ctx, e);
}
private final class Encoder extends HttpRequestEncoder {
Encoder() {
}
@Override
protected Object encode(ChannelHandlerContext ctx, Channel channel,
Object msg) throws Exception {
if (msg instanceof HttpRequest && !done) {
queue.offer(((HttpRequest) msg).getMethod());
}
Object obj = super.encode(ctx, channel, msg);
if (failOnMissingResponse) {
// check if the request is chunked if so do not increment
if (msg instanceof HttpRequest && !((HttpRequest) msg).isChunked()) {
requestResponseCounter.incrementAndGet();
} else if (msg instanceof HttpChunk && ((HttpChunk) msg).isLast()) {
// increment as its the last chunk
requestResponseCounter.incrementAndGet();
}
}
return obj;
}
}
private final class Decoder extends HttpResponseDecoder {
Decoder(int maxInitialLineLength, int maxHeaderSize, int maxChunkSize) {
super(maxInitialLineLength, maxHeaderSize, maxChunkSize);
}
@Override
protected Object decode(ChannelHandlerContext ctx, Channel channel,
ChannelBuffer buffer, State state) throws Exception {
if (done) {
int readable = actualReadableBytes();
if (readable == 0) {
return null;
}
return buffer.readBytes(readable);
} else {
Object msg = super.decode(ctx, channel, buffer, state);
if (failOnMissingResponse) {
decrement(msg);
}
return msg;
}
}
private void decrement(Object msg) {
if (msg == null) {
return;
}
// check if its a HttpMessage and its not chunked
if (msg instanceof HttpMessage && !((HttpMessage) msg).isChunked()) {
requestResponseCounter.decrementAndGet();
} else if (msg instanceof HttpChunk && ((HttpChunk) msg).isLast()) {
requestResponseCounter.decrementAndGet();
} else if (msg instanceof Object[]) {
// we just decrement it here as we only use this if the end of the chunk is reached
// It would be more safe to check all the objects in the array but would also be slower
requestResponseCounter.decrementAndGet();
}
}
@Override
protected boolean isContentAlwaysEmpty(HttpMessage msg) {
final int statusCode = ((HttpResponse) msg).getStatus().getCode();
if (statusCode == 100) {
// 100-continue response should be excluded from paired comparison.
return true;
}
// Get the method of the HTTP request that corresponds to the
// current response.
HttpMethod method = queue.poll();
char firstChar = method.getName().charAt(0);
switch (firstChar) {
case 'H':
// According to 4.3, RFC2616:
// All responses to the HEAD request method MUST NOT include a
// message-body, even though the presence of entity-header fields
// might lead one to believe they do.
if (HttpMethod.HEAD.equals(method)) {
return true;
// The following code was inserted to work around the servers
// that behave incorrectly. It has been commented out
// because it does not work with well behaving servers.
// Please note, even if the 'Transfer-Encoding: chunked'
// header exists in the HEAD response, the response should
// have absolutely no content.
//
//// Interesting edge case:
//// Some poorly implemented servers will send a zero-byte
//// chunk if Transfer-Encoding of the response is 'chunked'.
////
//// return !msg.isChunked();
}
break;
case 'C':
// Successful CONNECT request results in a response with empty body.
if (statusCode == 200) {
if (HttpMethod.CONNECT.equals(method)) {
// Proxy connection established - Not HTTP anymore.
done = true;
queue.clear();
return true;
}
}
break;
}
return super.isContentAlwaysEmpty(msg);
}
@Override
public void channelClosed(ChannelHandlerContext ctx, ChannelStateEvent e) throws Exception {
super.channelClosed(ctx, e);
if (failOnMissingResponse) {
long missingResponses = requestResponseCounter.get();
if (missingResponses > 0) {
throw new PrematureChannelClosureException(
"Channel closed but still missing " + missingResponses + " response(s)");
}
}
}
}
}