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1   /*
2    * Copyright 2015 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  
17  /*
18   * Copyright 2014 Twitter, Inc.
19   *
20   * Licensed under the Apache License, Version 2.0 (the "License");
21   * you may not use this file except in compliance with the License.
22   * You may obtain a copy of the License at
23   *
24   *     http://www.apache.org/licenses/LICENSE-2.0
25   *
26   * Unless required by applicable law or agreed to in writing, software
27   * distributed under the License is distributed on an "AS IS" BASIS,
28   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
29   * See the License for the specific language governing permissions and
30   * limitations under the License.
31   */
32  package io.netty.handler.codec.http2;
33  
34  import io.netty.handler.codec.UnsupportedValueConverter;
35  import io.netty.util.AsciiString;
36  
37  import java.util.Arrays;
38  import java.util.List;
39  
40  import static io.netty.handler.codec.http2.HpackUtil.equalsConstantTime;
41  
42  final class HpackStaticTable {
43  
44      // Appendix A: Static Table
45      // http://tools.ietf.org/html/rfc7541#appendix-A
46      private static final List<HpackHeaderField> STATIC_TABLE = Arrays.asList(
47      /*  1 */ newEmptyHeaderField(":authority"),
48      /*  2 */ newHeaderField(":method", "GET"),
49      /*  3 */ newHeaderField(":method", "POST"),
50      /*  4 */ newHeaderField(":path", "/"),
51      /*  5 */ newHeaderField(":path", "/index.html"),
52      /*  6 */ newHeaderField(":scheme", "http"),
53      /*  7 */ newHeaderField(":scheme", "https"),
54      /*  8 */ newHeaderField(":status", "200"),
55      /*  9 */ newHeaderField(":status", "204"),
56      /* 10 */ newHeaderField(":status", "206"),
57      /* 11 */ newHeaderField(":status", "304"),
58      /* 12 */ newHeaderField(":status", "400"),
59      /* 13 */ newHeaderField(":status", "404"),
60      /* 14 */ newHeaderField(":status", "500"),
61      /* 15 */ newEmptyHeaderField("accept-charset"),
62      /* 16 */ newHeaderField("accept-encoding", "gzip, deflate"),
63      /* 17 */ newEmptyHeaderField("accept-language"),
64      /* 18 */ newEmptyHeaderField("accept-ranges"),
65      /* 19 */ newEmptyHeaderField("accept"),
66      /* 20 */ newEmptyHeaderField("access-control-allow-origin"),
67      /* 21 */ newEmptyHeaderField("age"),
68      /* 22 */ newEmptyHeaderField("allow"),
69      /* 23 */ newEmptyHeaderField("authorization"),
70      /* 24 */ newEmptyHeaderField("cache-control"),
71      /* 25 */ newEmptyHeaderField("content-disposition"),
72      /* 26 */ newEmptyHeaderField("content-encoding"),
73      /* 27 */ newEmptyHeaderField("content-language"),
74      /* 28 */ newEmptyHeaderField("content-length"),
75      /* 29 */ newEmptyHeaderField("content-location"),
76      /* 30 */ newEmptyHeaderField("content-range"),
77      /* 31 */ newEmptyHeaderField("content-type"),
78      /* 32 */ newEmptyHeaderField("cookie"),
79      /* 33 */ newEmptyHeaderField("date"),
80      /* 34 */ newEmptyHeaderField("etag"),
81      /* 35 */ newEmptyHeaderField("expect"),
82      /* 36 */ newEmptyHeaderField("expires"),
83      /* 37 */ newEmptyHeaderField("from"),
84      /* 38 */ newEmptyHeaderField("host"),
85      /* 39 */ newEmptyHeaderField("if-match"),
86      /* 40 */ newEmptyHeaderField("if-modified-since"),
87      /* 41 */ newEmptyHeaderField("if-none-match"),
88      /* 42 */ newEmptyHeaderField("if-range"),
89      /* 43 */ newEmptyHeaderField("if-unmodified-since"),
90      /* 44 */ newEmptyHeaderField("last-modified"),
91      /* 45 */ newEmptyHeaderField("link"),
92      /* 46 */ newEmptyHeaderField("location"),
93      /* 47 */ newEmptyHeaderField("max-forwards"),
94      /* 48 */ newEmptyHeaderField("proxy-authenticate"),
95      /* 49 */ newEmptyHeaderField("proxy-authorization"),
96      /* 50 */ newEmptyHeaderField("range"),
97      /* 51 */ newEmptyHeaderField("referer"),
98      /* 52 */ newEmptyHeaderField("refresh"),
99      /* 53 */ newEmptyHeaderField("retry-after"),
100     /* 54 */ newEmptyHeaderField("server"),
101     /* 55 */ newEmptyHeaderField("set-cookie"),
102     /* 56 */ newEmptyHeaderField("strict-transport-security"),
103     /* 57 */ newEmptyHeaderField("transfer-encoding"),
104     /* 58 */ newEmptyHeaderField("user-agent"),
105     /* 59 */ newEmptyHeaderField("vary"),
106     /* 60 */ newEmptyHeaderField("via"),
107     /* 61 */ newEmptyHeaderField("www-authenticate")
108     );
109 
110     private static HpackHeaderField newEmptyHeaderField(String name) {
111         return new HpackHeaderField(AsciiString.cached(name), AsciiString.EMPTY_STRING);
112     }
113 
114     private static HpackHeaderField newHeaderField(String name, String value) {
115         return new HpackHeaderField(AsciiString.cached(name), AsciiString.cached(value));
116     }
117 
118     private static final CharSequenceMap<Integer> STATIC_INDEX_BY_NAME = createMap();
119 
120     /**
121      * The number of header fields in the static table.
122      */
123     static final int length = STATIC_TABLE.size();
124 
125     /**
126      * Return the header field at the given index value.
127      */
128     static HpackHeaderField getEntry(int index) {
129         return STATIC_TABLE.get(index - 1);
130     }
131 
132     /**
133      * Returns the lowest index value for the given header field name in the static table. Returns
134      * -1 if the header field name is not in the static table.
135      */
136     static int getIndex(CharSequence name) {
137         Integer index = STATIC_INDEX_BY_NAME.get(name);
138         if (index == null) {
139             return -1;
140         }
141         return index;
142     }
143 
144     /**
145      * Returns the index value for the given header field in the static table. Returns -1 if the
146      * header field is not in the static table.
147      */
148     static int getIndex(CharSequence name, CharSequence value) {
149         int index = getIndex(name);
150         if (index == -1) {
151             return -1;
152         }
153 
154         // Note this assumes all entries for a given header field are sequential.
155         while (index <= length) {
156             HpackHeaderField entry = getEntry(index);
157             if (equalsConstantTime(name, entry.name) == 0) {
158                 break;
159             }
160             if (equalsConstantTime(value, entry.value) != 0) {
161                 return index;
162             }
163             index++;
164         }
165 
166         return -1;
167     }
168 
169     // create a map CharSequenceMap header name to index value to allow quick lookup
170     private static CharSequenceMap<Integer> createMap() {
171         int length = STATIC_TABLE.size();
172         @SuppressWarnings("unchecked")
173         CharSequenceMap<Integer> ret = new CharSequenceMap<Integer>(true,
174                 UnsupportedValueConverter.<Integer>instance(), length);
175         // Iterate through the static table in reverse order to
176         // save the smallest index for a given name in the map.
177         for (int index = length; index > 0; index--) {
178             HpackHeaderField entry = getEntry(index);
179             CharSequence name = entry.name;
180             ret.set(name, index);
181         }
182         return ret;
183     }
184 
185     // singleton
186     private HpackStaticTable() {
187     }
188 }