1 /*
2 * Copyright 2012 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 * http://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.netty.handler.codec.http;
17
18 import io.netty.buffer.ByteBuf;
19 import io.netty.channel.ChannelPipeline;
20 import io.netty.handler.codec.TooLongFrameException;
21
22
23 /**
24 * Decodes {@link ByteBuf}s into {@link HttpResponse}s and
25 * {@link HttpContent}s.
26 *
27 * <h3>Parameters that prevents excessive memory consumption</h3>
28 * <table border="1">
29 * <tr>
30 * <th>Name</th><th>Meaning</th>
31 * </tr>
32 * <tr>
33 * <td>{@code maxInitialLineLength}</td>
34 * <td>The maximum length of the initial line (e.g. {@code "HTTP/1.0 200 OK"})
35 * If the length of the initial line exceeds this value, a
36 * {@link TooLongFrameException} will be raised.</td>
37 * </tr>
38 * <tr>
39 * <td>{@code maxHeaderSize}</td>
40 * <td>The maximum length of all headers. If the sum of the length of each
41 * header exceeds this value, a {@link TooLongFrameException} will be raised.</td>
42 * </tr>
43 * <tr>
44 * <td>{@code maxChunkSize}</td>
45 * <td>The maximum length of the content or each chunk. If the content length
46 * exceeds this value, the transfer encoding of the decoded response will be
47 * converted to 'chunked' and the content will be split into multiple
48 * {@link HttpContent}s. If the transfer encoding of the HTTP response is
49 * 'chunked' already, each chunk will be split into smaller chunks if the
50 * length of the chunk exceeds this value. If you prefer not to handle
51 * {@link HttpContent}s in your handler, insert {@link HttpObjectAggregator}
52 * after this decoder in the {@link ChannelPipeline}.</td>
53 * </tr>
54 * </table>
55 *
56 * <h3>Decoding a response for a <tt>HEAD</tt> request</h3>
57 * <p>
58 * Unlike other HTTP requests, the successful response of a <tt>HEAD</tt>
59 * request does not have any content even if there is <tt>Content-Length</tt>
60 * header. Because {@link HttpResponseDecoder} is not able to determine if the
61 * response currently being decoded is associated with a <tt>HEAD</tt> request,
62 * you must override {@link #isContentAlwaysEmpty(HttpMessage)} to return
63 * <tt>true</tt> for the response of the <tt>HEAD</tt> request.
64 * </p><p>
65 * If you are writing an HTTP client that issues a <tt>HEAD</tt> request,
66 * please use {@link HttpClientCodec} instead of this decoder. It will perform
67 * additional state management to handle the responses for <tt>HEAD</tt>
68 * requests correctly.
69 * </p>
70 *
71 * <h3>Decoding a response for a <tt>CONNECT</tt> request</h3>
72 * <p>
73 * You also need to do additional state management to handle the response of a
74 * <tt>CONNECT</tt> request properly, like you did for <tt>HEAD</tt>. One
75 * difference is that the decoder should stop decoding completely after decoding
76 * the successful 200 response since the connection is not an HTTP connection
77 * anymore.
78 * </p><p>
79 * {@link HttpClientCodec} also handles this edge case correctly, so you have to
80 * use {@link HttpClientCodec} if you are writing an HTTP client that issues a
81 * <tt>CONNECT</tt> request.
82 * </p>
83 */
84 public class HttpResponseDecoder extends HttpObjectDecoder {
85
86 private static final HttpResponseStatus UNKNOWN_STATUS = new HttpResponseStatus(999, "Unknown");
87
88 /**
89 * Creates a new instance with the default
90 * {@code maxInitialLineLength (4096)}, {@code maxHeaderSize (8192)}, and
91 * {@code maxChunkSize (8192)}.
92 */
93 public HttpResponseDecoder() {
94 }
95
96 /**
97 * Creates a new instance with the specified parameters.
98 */
99 public HttpResponseDecoder(
100 int maxInitialLineLength, int maxHeaderSize, int maxChunkSize) {
101 super(maxInitialLineLength, maxHeaderSize, maxChunkSize, DEFAULT_CHUNKED_SUPPORTED);
102 }
103
104 public HttpResponseDecoder(
105 int maxInitialLineLength, int maxHeaderSize, int maxChunkSize, boolean validateHeaders) {
106 super(maxInitialLineLength, maxHeaderSize, maxChunkSize, DEFAULT_CHUNKED_SUPPORTED, validateHeaders);
107 }
108
109 public HttpResponseDecoder(
110 int maxInitialLineLength, int maxHeaderSize, int maxChunkSize, boolean validateHeaders,
111 int initialBufferSize) {
112 super(maxInitialLineLength, maxHeaderSize, maxChunkSize, DEFAULT_CHUNKED_SUPPORTED, validateHeaders,
113 initialBufferSize);
114 }
115
116 public HttpResponseDecoder(
117 int maxInitialLineLength, int maxHeaderSize, int maxChunkSize, boolean validateHeaders,
118 int initialBufferSize, boolean allowDuplicateContentLengths) {
119 super(maxInitialLineLength, maxHeaderSize, maxChunkSize, DEFAULT_CHUNKED_SUPPORTED, validateHeaders,
120 initialBufferSize, allowDuplicateContentLengths);
121 }
122
123 @Override
124 protected HttpMessage createMessage(String[] initialLine) {
125 return new DefaultHttpResponse(
126 HttpVersion.valueOf(initialLine[0]),
127 HttpResponseStatus.valueOf(Integer.parseInt(initialLine[1]), initialLine[2]), validateHeaders);
128 }
129
130 @Override
131 protected HttpMessage createInvalidMessage() {
132 return new DefaultFullHttpResponse(HttpVersion.HTTP_1_0, UNKNOWN_STATUS, validateHeaders);
133 }
134
135 @Override
136 protected boolean isDecodingRequest() {
137 return false;
138 }
139 }
140