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.channel.ChannelHandlerContext;
19 import io.netty.channel.embedded.EmbeddedChannel;
20 import io.netty.handler.codec.compression.ZlibCodecFactory;
21 import io.netty.handler.codec.compression.ZlibWrapper;
22
23 /**
24 * Compresses an {@link HttpMessage} and an {@link HttpContent} in {@code gzip} or
25 * {@code deflate} encoding while respecting the {@code "Accept-Encoding"} header.
26 * If there is no matching encoding, no compression is done. For more
27 * information on how this handler modifies the message, please refer to
28 * {@link HttpContentEncoder}.
29 */
30 public class HttpContentCompressor extends HttpContentEncoder {
31
32 private final int compressionLevel;
33 private final int windowBits;
34 private final int memLevel;
35 private final int contentSizeThreshold;
36 private ChannelHandlerContext ctx;
37
38 /**
39 * Creates a new handler with the default compression level (<tt>6</tt>),
40 * default window size (<tt>15</tt>) and default memory level (<tt>8</tt>).
41 */
42 public HttpContentCompressor() {
43 this(6);
44 }
45
46 /**
47 * Creates a new handler with the specified compression level, default
48 * window size (<tt>15</tt>) and default memory level (<tt>8</tt>).
49 *
50 * @param compressionLevel
51 * {@code 1} yields the fastest compression and {@code 9} yields the
52 * best compression. {@code 0} means no compression. The default
53 * compression level is {@code 6}.
54 */
55 public HttpContentCompressor(int compressionLevel) {
56 this(compressionLevel, 15, 8, 0);
57 }
58
59 /**
60 * Creates a new handler with the specified compression level, window size,
61 * and memory level..
62 *
63 * @param compressionLevel
64 * {@code 1} yields the fastest compression and {@code 9} yields the
65 * best compression. {@code 0} means no compression. The default
66 * compression level is {@code 6}.
67 * @param windowBits
68 * The base two logarithm of the size of the history buffer. The
69 * value should be in the range {@code 9} to {@code 15} inclusive.
70 * Larger values result in better compression at the expense of
71 * memory usage. The default value is {@code 15}.
72 * @param memLevel
73 * How much memory should be allocated for the internal compression
74 * state. {@code 1} uses minimum memory and {@code 9} uses maximum
75 * memory. Larger values result in better and faster compression
76 * at the expense of memory usage. The default value is {@code 8}
77 */
78 public HttpContentCompressor(int compressionLevel, int windowBits, int memLevel) {
79 this(compressionLevel, windowBits, memLevel, 0);
80 }
81
82 /**
83 * Creates a new handler with the specified compression level, window size,
84 * and memory level..
85 *
86 * @param compressionLevel
87 * {@code 1} yields the fastest compression and {@code 9} yields the
88 * best compression. {@code 0} means no compression. The default
89 * compression level is {@code 6}.
90 * @param windowBits
91 * The base two logarithm of the size of the history buffer. The
92 * value should be in the range {@code 9} to {@code 15} inclusive.
93 * Larger values result in better compression at the expense of
94 * memory usage. The default value is {@code 15}.
95 * @param memLevel
96 * How much memory should be allocated for the internal compression
97 * state. {@code 1} uses minimum memory and {@code 9} uses maximum
98 * memory. Larger values result in better and faster compression
99 * at the expense of memory usage. The default value is {@code 8}
100 * @param contentSizeThreshold
101 * The response body is compressed when the size of the response
102 * body exceeds the threshold. The value should be a non negative
103 * number. {@code 0} will enable compression for all responses.
104 */
105 public HttpContentCompressor(int compressionLevel, int windowBits, int memLevel, int contentSizeThreshold) {
106 if (compressionLevel < 0 || compressionLevel > 9) {
107 throw new IllegalArgumentException(
108 "compressionLevel: " + compressionLevel +
109 " (expected: 0-9)");
110 }
111 if (windowBits < 9 || windowBits > 15) {
112 throw new IllegalArgumentException(
113 "windowBits: " + windowBits + " (expected: 9-15)");
114 }
115 if (memLevel < 1 || memLevel > 9) {
116 throw new IllegalArgumentException(
117 "memLevel: " + memLevel + " (expected: 1-9)");
118 }
119 if (contentSizeThreshold < 0) {
120 throw new IllegalArgumentException(
121 "contentSizeThreshold: " + contentSizeThreshold + " (expected: non negative number)");
122 }
123 this.compressionLevel = compressionLevel;
124 this.windowBits = windowBits;
125 this.memLevel = memLevel;
126 this.contentSizeThreshold = contentSizeThreshold;
127 }
128
129 @Override
130 public void handlerAdded(ChannelHandlerContext ctx) throws Exception {
131 this.ctx = ctx;
132 }
133
134 @Override
135 protected Result beginEncode(HttpResponse headers, String acceptEncoding) throws Exception {
136 if (this.contentSizeThreshold > 0) {
137 if (headers instanceof HttpContent &&
138 ((HttpContent) headers).content().readableBytes() < contentSizeThreshold) {
139 return null;
140 }
141 }
142
143 String contentEncoding = headers.headers().get(HttpHeaderNames.CONTENT_ENCODING);
144 if (contentEncoding != null) {
145 // Content-Encoding was set, either as something specific or as the IDENTITY encoding
146 // Therefore, we should NOT encode here
147 return null;
148 }
149
150 ZlibWrapper wrapper = determineWrapper(acceptEncoding);
151 if (wrapper == null) {
152 return null;
153 }
154
155 String targetContentEncoding;
156 switch (wrapper) {
157 case GZIP:
158 targetContentEncoding = "gzip";
159 break;
160 case ZLIB:
161 targetContentEncoding = "deflate";
162 break;
163 default:
164 throw new Error();
165 }
166
167 return new Result(
168 targetContentEncoding,
169 new EmbeddedChannel(ctx.channel().id(), ctx.channel().metadata().hasDisconnect(),
170 ctx.channel().config(), ZlibCodecFactory.newZlibEncoder(
171 wrapper, compressionLevel, windowBits, memLevel)));
172 }
173
174 @SuppressWarnings("FloatingPointEquality")
175 protected ZlibWrapper determineWrapper(String acceptEncoding) {
176 float starQ = -1.0f;
177 float gzipQ = -1.0f;
178 float deflateQ = -1.0f;
179 for (String encoding : acceptEncoding.split(",")) {
180 float q = 1.0f;
181 int equalsPos = encoding.indexOf('=');
182 if (equalsPos != -1) {
183 try {
184 q = Float.parseFloat(encoding.substring(equalsPos + 1));
185 } catch (NumberFormatException e) {
186 // Ignore encoding
187 q = 0.0f;
188 }
189 }
190 if (encoding.contains("*")) {
191 starQ = q;
192 } else if (encoding.contains("gzip") && q > gzipQ) {
193 gzipQ = q;
194 } else if (encoding.contains("deflate") && q > deflateQ) {
195 deflateQ = q;
196 }
197 }
198 if (gzipQ > 0.0f || deflateQ > 0.0f) {
199 if (gzipQ >= deflateQ) {
200 return ZlibWrapper.GZIP;
201 } else {
202 return ZlibWrapper.ZLIB;
203 }
204 }
205 if (starQ > 0.0f) {
206 if (gzipQ == -1.0f) {
207 return ZlibWrapper.GZIP;
208 }
209 if (deflateQ == -1.0f) {
210 return ZlibWrapper.ZLIB;
211 }
212 }
213 return null;
214 }
215 }