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/*
 * Copyright 2017 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.codec.http;

import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.util.ReferenceCountUtil;

import static io.netty.handler.codec.http.HttpHeaderNames.CONTENT_LENGTH;
import static io.netty.handler.codec.http.HttpResponseStatus.CONTINUE;
import static io.netty.handler.codec.http.HttpVersion.HTTP_1_1;

/**
 * Sends a 100 CONTINUE
 * {@link HttpResponse} to {@link HttpRequest}s which contain a 'expect: 100-continue' header. It
 * should only be used for applications which do not install the {@link HttpObjectAggregator}.
 * 

* By default it accepts all expectations. *

* Since {@link HttpServerExpectContinueHandler} expects {@link HttpRequest}s it should be added after {@link * HttpServerCodec} but before any other handlers that might send a {@link HttpResponse}.

*
 *  {@link io.netty.channel.ChannelPipeline} p = ...;
 *  ...
 *  p.addLast("serverCodec", new {@link HttpServerCodec}());
 *  p.addLast("respondExpectContinue", new {@link HttpServerExpectContinueHandler}());
 *  ...
 *  p.addLast("handler", new HttpRequestHandler());
 *  
*
*/ public class HttpServerExpectContinueHandler extends ChannelInboundHandlerAdapter { private static final FullHttpResponse EXPECTATION_FAILED = new DefaultFullHttpResponse( HTTP_1_1, HttpResponseStatus.EXPECTATION_FAILED, Unpooled.EMPTY_BUFFER); private static final FullHttpResponse ACCEPT = new DefaultFullHttpResponse( HTTP_1_1, CONTINUE, Unpooled.EMPTY_BUFFER); static { EXPECTATION_FAILED.headers().set(CONTENT_LENGTH, 0); ACCEPT.headers().set(CONTENT_LENGTH, 0); } /** * Produces a {@link HttpResponse} for {@link HttpRequest}s which define an expectation. Returns {@code null} if the * request should be rejected. See {@link #rejectResponse(HttpRequest)}. */ protected HttpResponse acceptMessage(@SuppressWarnings("unused") HttpRequest request) { return ACCEPT.retainedDuplicate(); } /** * Returns the appropriate 4XX {@link HttpResponse} for the given {@link HttpRequest}. */ protected HttpResponse rejectResponse(@SuppressWarnings("unused") HttpRequest request) { return EXPECTATION_FAILED.retainedDuplicate(); } @Override public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception { if (msg instanceof HttpRequest) { HttpRequest req = (HttpRequest) msg; if (HttpUtil.is100ContinueExpected(req)) { HttpResponse accept = acceptMessage(req); if (accept == null) { // the expectation failed so we refuse the request. HttpResponse rejection = rejectResponse(req); ReferenceCountUtil.release(msg); ctx.writeAndFlush(rejection).addListener(ChannelFutureListener.CLOSE_ON_FAILURE); return; } ctx.writeAndFlush(accept).addListener(ChannelFutureListener.CLOSE_ON_FAILURE); req.headers().remove(HttpHeaderNames.EXPECT); } } super.channelRead(ctx, msg); } }




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