1 /*

     2  * Copyright (c) 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  */

    24 package java.net.http;

    25 

    26 import java.nio.ByteBuffer;

    27 import java.nio.CharBuffer;

    28 import java.nio.charset.CharacterCodingException;

    29 import java.nio.charset.CharsetDecoder;

    30 import java.nio.charset.CharsetEncoder;

    31 import java.nio.charset.CoderResult;

    32 

    33 import static java.nio.charset.StandardCharsets.UTF_8;

    34 

    35 // The purpose of this class is to separate charset-related tasks from the main

    36 // WebSocket logic, simplifying where possible.

    37 //

    38 //     * Coders hide the differences between coding and flushing stages on the

    39 //       API level

    40 //     * Verifier abstracts the way the verification is performed

    41 //       (spoiler: it's a decoding into a throw-away buffer)

    42 //

    43 // Coding methods throw exceptions instead of returning coding result denoting

    44 // errors, since any kind of handling and recovery is not expected.

    45 final class CharsetToolkit {

    46 

    47     private CharsetToolkit() { }

    48 

    49     static final class Verifier {

    50 

    51         private final CharsetDecoder decoder = UTF_8.newDecoder();

    52         // A buffer used to check validity of UTF-8 byte stream by decoding it.

    53         // The contents of this buffer are never used.

    54         // The size is arbitrary, though it should probably be chosen from the

    55         // performance perspective since it affects the total number of calls to

    56         // decoder.decode() and amount of work in each of these calls

    57         private final CharBuffer blackHole = CharBuffer.allocate(1024);

    58 

    59         void verify(ByteBuffer in, boolean endOfInput)

    60                 throws CharacterCodingException {

    61             while (true) {

    62                 // Since decoder.flush() cannot produce an error, it's not

    63                 // helpful for verification. Therefore this step is skipped.

    64                 CoderResult r = decoder.decode(in, blackHole, endOfInput);

    65                 if (r.isOverflow()) {

    66                     blackHole.clear();

    67                 } else if (r.isUnderflow()) {

    68                     break;

    69                 } else if (r.isError()) {

    70                     r.throwException();

    71                 } else {

    72                     // Should not happen

    73                     throw new InternalError();

    74                 }

    75             }

    76         }

    77 

    78         Verifier reset() {

    79             decoder.reset();

    80             return this;

    81         }

    82     }

    83 

    84     static final class Encoder {

    85 

    86         private final CharsetEncoder encoder = UTF_8.newEncoder();

    87         private boolean coding = true;

    88 

    89         CoderResult encode(CharBuffer in, ByteBuffer out, boolean endOfInput)

    90                 throws CharacterCodingException {

    91 

    92             if (coding) {

    93                 CoderResult r = encoder.encode(in, out, endOfInput);

    94                 if (r.isOverflow()) {

    95                     return r;

    96                 } else if (r.isUnderflow()) {

    97                     if (endOfInput) {

    98                         coding = false;

    99                     } else {

   100                         return r;

   101                     }

   102                 } else if (r.isError()) {

   103                     r.throwException();

   104                 } else {

   105                     // Should not happen

   106                     throw new InternalError();

   107                 }

   108             }

   109             assert !coding;

   110             return encoder.flush(out);

   111         }

   112 

   113         Encoder reset() {

   114             coding = true;

   115             encoder.reset();

   116             return this;

   117         }

   118     }

   119 

   120     static CharBuffer decode(ByteBuffer in) throws CharacterCodingException {

   121         return UTF_8.newDecoder().decode(in);

   122     }

   123 

   124     static final class Decoder {

   125 

   126         private final CharsetDecoder decoder = UTF_8.newDecoder();

   127         private boolean coding = true; // Either coding or flushing

   128 

   129         CoderResult decode(ByteBuffer in, CharBuffer out, boolean endOfInput)

   130                 throws CharacterCodingException {

   131 

   132             if (coding) {

   133                 CoderResult r = decoder.decode(in, out, endOfInput);

   134                 if (r.isOverflow()) {

   135                     return r;

   136                 } else if (r.isUnderflow()) {

   137                     if (endOfInput) {

   138                         coding = false;

   139                     } else {

   140                         return r;

   141                     }

   142                 } else if (r.isError()) {

   143                     r.throwException();

   144                 } else {

   145                     // Should not happen

   146                     throw new InternalError();

   147                 }

   148             }

   149             assert !coding;

   150             return decoder.flush(out);

   151         }

   152 

   153         Decoder reset() {

   154             coding = true;

   155             decoder.reset();

   156             return this;

   157         }

   158     }

   159 }