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1   /*
2    * Copyright 2025 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.netty.handler.codec.http3;
17  
18  import org.jetbrains.annotations.Nullable;
19  
20  import java.util.Arrays;
21  import java.util.Collections;
22  import java.util.HashMap;
23  import java.util.Map;
24  import java.util.function.Function;
25  import java.util.stream.Collectors;
26  
27  public enum Http3SettingIdentifier {
28  
29      /**
30       * QPACK maximum table capacity setting identifier (<b>0x1</b>).
31       * <p>
32       * Defined in <a href="https://datatracker.ietf.org/doc/html/rfc9204#section-5">
33       * RFC 9204, Section 5 (SETTINGS_QPACK_MAX_TABLE_CAPACITY)</a> and registered in
34       * the <a href="https://www.iana.org/assignments/http3-parameters/http3-parameters.xhtml#settings">
35       * HTTP/3 SETTINGS registry (IANA)</a>.
36       * <br>
37       * Controls the maximum size of the dynamic table used by QPACK.
38       */
39      HTTP3_SETTINGS_QPACK_MAX_TABLE_CAPACITY(0x1),
40  
41      /**
42       * Maximum field section size setting identifier (<b>0x6</b>).
43       * <p>
44       * Defined in <a href="https://datatracker.ietf.org/doc/html/rfc9114#section-7.2.4.1">
45       * RFC 9114, Section 7.2.4.1 (SETTINGS_MAX_FIELD_SECTION_SIZE)</a> , also referenced
46       * in the <a href="https://datatracker.ietf.org/doc/html/rfc9114#section-7.2.4.1">
47       * HTTP/3 SETTINGS registry (RFC 9114, Section 7.2.4.1)</a> and registered in
48       * the <a href="https://www.iana.org/assignments/http3-parameters/http3-parameters.xhtml#settings">
49       * HTTP/3 SETTINGS registry (IANA)</a>.
50       * <br>
51       * Specifies the upper bound on the total size of HTTP field sections accepted by a peer.
52       */
53      HTTP3_SETTINGS_MAX_FIELD_SECTION_SIZE(0x6),
54  
55      /**
56       * QPACK blocked streams setting identifier (<b>0x7</b>).
57       * <p>
58       * Defined in <a href="https://datatracker.ietf.org/doc/html/rfc9204#section-5">
59       * RFC 9204, Section 5 (SETTINGS_QPACK_BLOCKED_STREAMS)</a> and registered in
60       * the <a href="https://www.iana.org/assignments/http3-parameters/http3-parameters.xhtml#settings">
61       * HTTP/3 SETTINGS registry (IANA)</a>.
62       * <br>
63       * Indicates the maximum number of streams that can be blocked waiting for QPACK instructions.
64       */
65      HTTP3_SETTINGS_QPACK_BLOCKED_STREAMS(0x7),
66  
67      /**
68       * ENABLE_CONNECT_PROTOCOL setting identifier (<b>0x8</b>).
69       * <p>
70       * Defined and registered in <a href="https://datatracker.ietf.org/doc/html/rfc9220#section-5">
71       * RFC 9220, Section 5 (IANA Considerations)</a> and registered in
72       * the <a href="https://www.iana.org/assignments/http3-parameters/http3-parameters.xhtml#settings">
73       * HTTP/3 SETTINGS registry (IANA)</a>.
74       * <br>
75       * Enables use of the CONNECT protocol in HTTP/3 when set to 1; disabled when 0.
76       */
77      HTTP3_SETTINGS_ENABLE_CONNECT_PROTOCOL(0x8),
78  
79      /**
80       * ENABLE_H3_DATAGRAM setting identifier (<b>0x8</b>).
81       * <p>
82       * Defined and registered in <a href="https://datatracker.ietf.org/doc/html/rfc9297#name-http-3-setting">
83       * RFC 9220, Section 5 (IANA Considerations)</a> and registered in
84       * the <a href="https://www.iana.org/assignments/http3-parameters/http3-parameters.xhtml#settings">
85       * HTTP/3 SETTINGS registry (IANA)</a>.
86       * <br>
87       * Enables use of the CONNECT protocol in HTTP/3 when set to 1; disabled when 0.
88       */
89      HTTP3_SETTINGS_H3_DATAGRAM(0x33);
90  
91      private final long id;
92  
93      private static final Map<Long, Http3SettingIdentifier> LOOKUP = Collections.unmodifiableMap(
94          Arrays.stream(values()).collect(Collectors.toMap(Http3SettingIdentifier::id, Function.identity()))
95      );
96  
97      Http3SettingIdentifier(long id) {
98          this.id = id;
99      }
100 
101     /**
102      * Returns the Identifier of {@link Http3SettingIdentifier}
103      * for example:
104      * SETTINGS_QPACK_MAX_TABLE_CAPACITY = 0x1 = 1 in the settings frame
105      * <br>
106      * @return long(represented as hexadecimal above) value of the Identifier
107      */
108     public long id() {
109         return id;
110     }
111 
112     /**
113      * Returns {@link Http3SettingIdentifier}
114      * @param id
115      * @return {@link Http3SettingIdentifier} enum which represents @param id, null otherwise
116      */
117     @Nullable
118     public static Http3SettingIdentifier fromId(long id) {
119         return LOOKUP.get(id);
120     }
121 }