1 /*
2 * Copyright 2017 The Netty Project
3 *
4 * The Netty Project licenses this file to you under the Apache License,
5 * version 2.0 (the "License"); you may not use this file except in compliance
6 * with the License. You may obtain a copy of the License at:
7 *
8 * https://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13 * License for the specific language governing permissions and limitations
14 * under the License.
15 */
16 package io.netty5.handler.codec.http;
17
18 import io.netty5.buffer.api.BufferAllocator;
19 import io.netty5.channel.ChannelFutureListeners;
20 import io.netty5.channel.ChannelHandler;
21 import io.netty5.channel.ChannelHandlerContext;
22 import io.netty5.util.Resource;
23
24 import static io.netty5.handler.codec.http.HttpHeaderNames.CONTENT_LENGTH;
25 import static io.netty5.handler.codec.http.HttpResponseStatus.CONTINUE;
26 import static io.netty5.handler.codec.http.HttpResponseStatus.EXPECTATION_FAILED;
27 import static io.netty5.handler.codec.http.HttpVersion.HTTP_1_1;
28
29 /**
30 * Sends a <a href="https://www.w3.org/Protocols/rfc2616/rfc2616-sec8.html#sec8.2.3">100 CONTINUE</a>
31 * {@link HttpResponse} to {@link HttpRequest}s which contain a 'expect: 100-continue' header. It
32 * should only be used for applications which do <b>not</b> install the {@link HttpObjectAggregator}.
33 * <p>
34 * By default it accepts all expectations.
35 * <p>
36 * Since {@link HttpServerExpectContinueHandler} expects {@link HttpRequest}s it should be added after {@link
37 * HttpServerCodec} but before any other handlers that might send a {@link HttpResponse}. <blockquote>
38 * <pre>
39 * {@link io.netty5.channel.ChannelPipeline} p = ...;
40 * ...
41 * p.addLast("serverCodec", new {@link HttpServerCodec}());
42 * p.addLast("respondExpectContinue", <b>new {@link HttpServerExpectContinueHandler}()</b>);
43 * ...
44 * p.addLast("handler", new HttpRequestHandler());
45 * </pre>
46 * </blockquote>
47 */
48 public class HttpServerExpectContinueHandler implements ChannelHandler {
49 /**
50 * Produces a {@link HttpResponse} for {@link HttpRequest}s which define an expectation. Returns {@code null} if the
51 * request should be rejected. See {@link #rejectResponse(BufferAllocator, HttpRequest)}.
52 */
53 protected HttpResponse acceptMessage(BufferAllocator allocator, @SuppressWarnings("unused") HttpRequest request) {
54 return newEmptyResponse(allocator, CONTINUE);
55 }
56
57 /**
58 * Returns the appropriate 4XX {@link HttpResponse} for the given {@link HttpRequest}.
59 */
60 protected HttpResponse rejectResponse(BufferAllocator allocator, @SuppressWarnings("unused") HttpRequest request) {
61 return newEmptyResponse(allocator, EXPECTATION_FAILED);
62 }
63
64 private static DefaultFullHttpResponse newEmptyResponse(BufferAllocator allocator, HttpResponseStatus status) {
65 final DefaultFullHttpResponse resp = new DefaultFullHttpResponse(HTTP_1_1, status, allocator.allocate(0));
66 resp.headers().set(CONTENT_LENGTH, 0);
67 return resp;
68 }
69
70 @Override
71 public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
72 if (msg instanceof HttpRequest) {
73 HttpRequest req = (HttpRequest) msg;
74
75 if (HttpUtil.is100ContinueExpected(req)) {
76 HttpResponse accept = acceptMessage(ctx.bufferAllocator(), req);
77
78 if (accept == null) {
79 // the expectation failed so we refuse the request.
80 HttpResponse rejection = rejectResponse(ctx.bufferAllocator(), req);
81 Resource.dispose(msg);
82 ctx.writeAndFlush(rejection).addListener(ctx.channel(), ChannelFutureListeners.CLOSE_ON_FAILURE);
83 return;
84 }
85
86 ctx.writeAndFlush(accept).addListener(ctx.channel(), ChannelFutureListeners.CLOSE_ON_FAILURE);
87 req.headers().remove(HttpHeaderNames.EXPECT);
88 }
89 }
90 ctx.fireChannelRead(msg);
91 }
92 }