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.embedded.EmbeddedChannel;
19 import io.netty.handler.codec.compression.ZlibCodecFactory;
20 import io.netty.handler.codec.compression.ZlibWrapper;
21 import io.netty.util.internal.StringUtil;
22
23 /**
24 * Compresses an [email protected] HttpMessage} and an [email protected] HttpContent} in [email protected] gzip} or
25 * [email protected] deflate} encoding while respecting the [email protected] "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 * [email protected] 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
36 /**
37 * Creates a new handler with the default compression level (<tt>6</tt>),
38 * default window size (<tt>15</tt>) and default memory level (<tt>8</tt>).
39 */
40 public HttpContentCompressor() {
41 this(6);
42 }
43
44 /**
45 * Creates a new handler with the specified compression level, default
46 * window size (<tt>15</tt>) and default memory level (<tt>8</tt>).
47 *
48 * @param compressionLevel
49 * [email protected] 1} yields the fastest compression and [email protected] 9} yields the
50 * best compression. [email protected] 0} means no compression. The default
51 * compression level is [email protected] 6}.
52 */
53 public HttpContentCompressor(int compressionLevel) {
54 this(compressionLevel, 15, 8);
55 }
56
57 /**
58 * Creates a new handler with the specified compression level, window size,
59 * and memory level..
60 *
61 * @param compressionLevel
62 * [email protected] 1} yields the fastest compression and [email protected] 9} yields the
63 * best compression. [email protected] 0} means no compression. The default
64 * compression level is [email protected] 6}.
65 * @param windowBits
66 * The base two logarithm of the size of the history buffer. The
67 * value should be in the range [email protected] 9} to [email protected] 15} inclusive.
68 * Larger values result in better compression at the expense of
69 * memory usage. The default value is [email protected] 15}.
70 * @param memLevel
71 * How much memory should be allocated for the internal compression
72 * state. [email protected] 1} uses minimum memory and [email protected] 9} uses maximum
73 * memory. Larger values result in better and faster compression
74 * at the expense of memory usage. The default value is [email protected] 8}
75 */
76 public HttpContentCompressor(int compressionLevel, int windowBits, int memLevel) {
77 if (compressionLevel < 0 || compressionLevel > 9) {
78 throw new IllegalArgumentException(
79 "compressionLevel: " + compressionLevel +
80 " (expected: 0-9)");
81 }
82 if (windowBits < 9 || windowBits > 15) {
83 throw new IllegalArgumentException(
84 "windowBits: " + windowBits + " (expected: 9-15)");
85 }
86 if (memLevel < 1 || memLevel > 9) {
87 throw new IllegalArgumentException(
88 "memLevel: " + memLevel + " (expected: 1-9)");
89 }
90 this.compressionLevel = compressionLevel;
91 this.windowBits = windowBits;
92 this.memLevel = memLevel;
93 }
94
95 @Override
96 protected Result beginEncode(HttpResponse headers, String acceptEncoding) throws Exception {
97 String contentEncoding = headers.headers().get(HttpHeaders.Names.CONTENT_ENCODING);
98 if (contentEncoding != null &&
99 !HttpHeaders.Values.IDENTITY.equalsIgnoreCase(contentEncoding)) {
100 return null;
101 }
102
103 ZlibWrapper wrapper = determineWrapper(acceptEncoding);
104 if (wrapper == null) {
105 return null;
106 }
107
108 String targetContentEncoding;
109 switch (wrapper) {
110 case GZIP:
111 targetContentEncoding = "gzip";
112 break;
113 case ZLIB:
114 targetContentEncoding = "deflate";
115 break;
116 default:
117 throw new Error();
118 }
119
120 return new Result(
121 targetContentEncoding,
122 new EmbeddedChannel(ZlibCodecFactory.newZlibEncoder(
123 wrapper, compressionLevel, windowBits, memLevel)));
124 }
125
126 @SuppressWarnings("FloatingPointEquality")
127 protected ZlibWrapper determineWrapper(String acceptEncoding) {
128 float starQ = -1.0f;
129 float gzipQ = -1.0f;
130 float deflateQ = -1.0f;
131 for (String encoding: StringUtil.split(acceptEncoding, ',')) {
132 float q = 1.0f;
133 int equalsPos = encoding.indexOf('=');
134 if (equalsPos != -1) {
135 try {
136 q = Float.valueOf(encoding.substring(equalsPos + 1));
137 } catch (NumberFormatException e) {
138 // Ignore encoding
139 q = 0.0f;
140 }
141 }
142 if (encoding.contains("*")) {
143 starQ = q;
144 } else if (encoding.contains("gzip") && q > gzipQ) {
145 gzipQ = q;
146 } else if (encoding.contains("deflate") && q > deflateQ) {
147 deflateQ = q;
148 }
149 }
150 if (gzipQ > 0.0f || deflateQ > 0.0f) {
151 if (gzipQ >= deflateQ) {
152 return ZlibWrapper.GZIP;
153 } else {
154 return ZlibWrapper.ZLIB;
155 }
156 }
157 if (starQ > 0.0f) {
158 if (gzipQ == -1.0f) {
159 return ZlibWrapper.GZIP;
160 }
161 if (deflateQ == -1.0f) {
162 return ZlibWrapper.ZLIB;
163 }
164 }
165 return null;
166 }
167 }