1 /*
2 * Copyright (c) 2015, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.net.http;
27
28 import java.nio.ByteBuffer;
29 import java.nio.CharBuffer;
30 import java.nio.charset.CharacterCodingException;
31 import java.nio.charset.CharsetDecoder;
32 import java.nio.charset.CharsetEncoder;
33 import java.nio.charset.CoderResult;
34
35 import static java.nio.charset.StandardCharsets.UTF_8;
36
37 // The purpose of this class is to separate charset-related tasks from the main
38 // WebSocket logic, simplifying where possible.
39 //
40 // * Coders hide the differences between coding and flushing stages on the
41 // API level
42 // * Verifier abstracts the way the verification is performed
43 // (spoiler: it's a decoding into a throw-away buffer)
44 //
45 // Coding methods throw exceptions instead of returning coding result denoting
46 // errors, since any kind of handling and recovery is not expected.
47 final class CharsetToolkit {
48
49 private CharsetToolkit() { }
50
51 static final class Verifier {
52
53 private final CharsetDecoder decoder = UTF_8.newDecoder();
54 // A buffer used to check validity of UTF-8 byte stream by decoding it.
55 // The contents of this buffer are never used.
56 // The size is arbitrary, though it should probably be chosen from the
57 // performance perspective since it affects the total number of calls to
58 // decoder.decode() and amount of work in each of these calls
59 private final CharBuffer blackHole = CharBuffer.allocate(1024);
60
61 void verify(ByteBuffer in, boolean endOfInput)
62 throws CharacterCodingException {
63 while (true) {
64 // Since decoder.flush() cannot produce an error, it's not
65 // helpful for verification. Therefore this step is skipped.
66 CoderResult r = decoder.decode(in, blackHole, endOfInput);
67 if (r.isOverflow()) {
68 blackHole.clear();
69 } else if (r.isUnderflow()) {
70 break;
71 } else if (r.isError()) {
72 r.throwException();
73 } else {
74 // Should not happen
75 throw new InternalError();
76 }
77 }
78 }
79
80 Verifier reset() {
81 decoder.reset();
82 return this;
83 }
84 }
85
86 static final class Encoder {
87
88 private final CharsetEncoder encoder = UTF_8.newEncoder();
89 private boolean coding = true;
90
91 CoderResult encode(CharBuffer in, ByteBuffer out, boolean endOfInput)
92 throws CharacterCodingException {
93
94 if (coding) {
95 CoderResult r = encoder.encode(in, out, endOfInput);
96 if (r.isOverflow()) {
97 return r;
98 } else if (r.isUnderflow()) {
99 if (endOfInput) {
100 coding = false;
101 } else {
102 return r;
103 }
104 } else if (r.isError()) {
105 r.throwException();
106 } else {
107 // Should not happen
108 throw new InternalError();
109 }
110 }
111 assert !coding;
112 return encoder.flush(out);
113 }
114
115 Encoder reset() {
116 coding = true;
117 encoder.reset();
118 return this;
119 }
120 }
121
122 static CharBuffer decode(ByteBuffer in) throws CharacterCodingException {
123 return UTF_8.newDecoder().decode(in);
124 }
125
126 static final class Decoder {
127
128 private final CharsetDecoder decoder = UTF_8.newDecoder();
129 private boolean coding = true; // Either coding or flushing
130
131 CoderResult decode(ByteBuffer in, CharBuffer out, boolean endOfInput)
132 throws CharacterCodingException {
133
134 if (coding) {
135 CoderResult r = decoder.decode(in, out, endOfInput);
136 if (r.isOverflow()) {
137 return r;
138 } else if (r.isUnderflow()) {
139 if (endOfInput) {
140 coding = false;
141 } else {
142 return r;
143 }
144 } else if (r.isError()) {
145 r.throwException();
146 } else {
147 // Should not happen
148 throw new InternalError();
149 }
150 }
151 assert !coding;
152 return decoder.flush(out);
153 }
154
155 Decoder reset() {
156 coding = true;
157 decoder.reset();
158 return this;
159 }
160 }
161 }