1 /*

     2  * Copyright (c) 2015, 2018, 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 jdk.internal.net.http.websocket;

    27 

    28 import jdk.internal.net.http.common.Log;

    29 

    30 import java.nio.ByteBuffer;

    31 import java.nio.CharBuffer;

    32 import java.nio.charset.CharacterCodingException;

    33 import java.nio.charset.CharsetDecoder;

    34 import java.nio.charset.CoderResult;

    35 import java.nio.charset.CodingErrorAction;

    36 

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

    38 import static jdk.internal.net.http.common.Utils.EMPTY_BYTEBUFFER;

    39 

    40 final class UTF8AccumulatingDecoder {

    41 

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

    43 

    44     {

    45         decoder.onMalformedInput(CodingErrorAction.REPORT);

    46         decoder.onUnmappableCharacter(CodingErrorAction.REPORT);

    47     }

    48 

    49     private ByteBuffer leftovers = EMPTY_BYTEBUFFER;

    50 

    51     CharBuffer decode(ByteBuffer in, boolean endOfInput)

    52             throws CharacterCodingException

    53     {

    54         ByteBuffer b;

    55         int rem = leftovers.remaining();

    56         if (rem != 0) {

    57             // We won't need this wasteful allocation & copying when JDK-8155222

    58             // has been resolved

    59             b = ByteBuffer.allocate(rem + in.remaining());

    60             b.put(leftovers).put(in).flip();

    61         } else {

    62             b = in;

    63         }

    64         CharBuffer out = CharBuffer.allocate(b.remaining());

    65         CoderResult r = decoder.decode(b, out, endOfInput);

    66         if (r.isError()) {

    67             r.throwException();

    68         }

    69         if (b.hasRemaining()) {

    70             leftovers = ByteBuffer.allocate(b.remaining()).put(b).flip();

    71         } else {

    72             leftovers = EMPTY_BYTEBUFFER;

    73         }

    74         // Since it's UTF-8, the assumption is leftovers.remaining() < 4

    75         // (i.e. small). Otherwise a shared buffer should be used

    76         if (!(leftovers.remaining() < 4)) {

    77             Log.logError("The size of decoding leftovers is greater than expected: {0}",

    78                          leftovers.remaining());

    79         }

    80         b.position(b.limit()); // As if we always read to the end

    81         // Decoder promises that in the case of endOfInput == true:

    82         // "...any remaining undecoded input will be treated as being

    83         // malformed"

    84         assert !(endOfInput && leftovers.hasRemaining()) : endOfInput + ", " + leftovers;

    85         if (endOfInput) {

    86             r = decoder.flush(out);

    87             decoder.reset();

    88             if (r.isOverflow()) {

    89                 // FIXME: for now I know flush() does nothing. But the

    90                 // implementation of UTF8 decoder might change. And if now

    91                 // flush() is a no-op, it is not guaranteed to remain so in

    92                 // the future

    93                 throw new InternalError("Not yet implemented");

    94             }

    95         }

    96         return out.flip();

    97     }

    98 }