зеркало из https://github.com/mozilla/gecko-dev.git
182 строки
6.6 KiB
Java
182 строки
6.6 KiB
Java
/* -*- Mode: java; indent-tabs-mode: nil; c-basic-offset: 2 -*-
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*
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* The contents of this file are subject to the Mozilla Public License
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* Version 1.0 (the "License"); you may not use this file except in
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* compliance with the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS IS"
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* basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
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* the License for the specific language governing rights and limitations
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* under the License.
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*
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* The Original Code is the Grendel mail/news client.
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*
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* The Initial Developer of the Original Code is Netscape Communications
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* Corporation. Portions created by Netscape are Copyright (C) 1997
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* Netscape Communications Corporation. All Rights Reserved.
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*
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* Created: Jamie Zawinski <jwz@netscape.com>, 28 Aug 1997.
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*/
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package grendel.mime.encoder;
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import calypso.util.ByteBuf;
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/** Implements a plaintext -> Base64 encoder.
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*/
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public final class MimeBase64Decoder extends MimeEncoder {
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private byte token[] = new byte[4]; // input buffer
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private byte bytes[] = new byte[3]; // output buffer
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private int token_length = 0; // input buffer length
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static private final byte NUL = 127; // must be out of range 0-64
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static private final byte EOF = 126; // must be out of range 0-64
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static private final byte map[] = {
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NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 000-007
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NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 010-017
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NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 020-027
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NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 030-037
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NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 040-047 !"#$%&'
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NUL, NUL, NUL, 62, NUL, NUL, NUL, 63, // 050-057 ()*+,-./
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52, 53, 54, 55, 56, 57, 58, 59, // 060-067 01234567
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60, 61, NUL, NUL, NUL, EOF, NUL, NUL, // 070-077 89:;<=>?
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NUL, 0, 1, 2, 3, 4, 5, 6, // 100-107 @ABCDEFG
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7, 8, 9, 10, 11, 12, 13, 14, // 110-117 HIJKLMNO
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15, 16, 17, 18, 19, 20, 21, 22, // 120-127 PQRSTUVW
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23, 24, 25, NUL, NUL, NUL, NUL, NUL, // 130-137 XYZ[\]^_
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NUL, 26, 27, 28, 29, 30, 31, 32, // 140-147 `abcdefg
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33, 34, 35, 36, 37, 38, 39, 40, // 150-157 hijklmno
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41, 42, 43, 44, 45, 46, 47, 48, // 160-167 pqrstuvw
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49, 50, 51, NUL, NUL, NUL, NUL, NUL, // 170-177 xyz{|}~
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NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 200-207
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NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 210-217
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NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 220-227
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NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 230-237
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NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 240-247
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NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 250-257
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NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 260-267
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NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 270-277
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NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 300-307
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NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 310-317
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NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 320-327
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NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 330-337
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NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 340-347
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NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 350-357
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NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 360-367
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NUL, NUL, NUL, NUL, NUL, NUL, NUL, NUL, // 370-377
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};
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// Fast routine that assumes full 4-char tokens with no '=' in them.
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//
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private final void decode_token(ByteBuf out) {
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int num = ((map[token[0]] << 18) |
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(map[token[1]] << 12) |
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(map[token[2]] << 6) |
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(map[token[3]]));
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bytes[0] = (byte) (0xFF & (num >> 16));
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bytes[1] = (byte) (0xFF & (num >> 8));
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bytes[2] = (byte) (0xFF & num);
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out.append(bytes);
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}
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// Hairier routine that deals with the final token, which can have fewer
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// than four characters, and that might be padded with '='.
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//
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private final void decode_final_token(ByteBuf out) {
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byte b0 = map[token[0]];
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byte b1 = map[token[1]];
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byte b2 = map[token[2]];
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byte b3 = map[token[3]];
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int eq_count = 0;
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if (b0 == EOF) { b0 = 0; eq_count++; }
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if (b1 == EOF) { b1 = 0; eq_count++; }
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if (b2 == EOF) { b2 = 0; eq_count++; }
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if (b3 == EOF) { b3 = 0; eq_count++; }
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int num = ((b0 << 18) | (b1 << 12) | (b2 << 6) | (b3));
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// eq_count will be 0, 1, or 2.
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// No "=" padding means 4 bytes mapped to 3, the normal case,
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// not handled in this routine.
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// "xxx=" means 3 bytes mapped to 2.
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// "xx==" means 2 bytes mapped to 1.
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// "x===" can't happen, because "x" would then be encoding
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// only 6 bits, not 8, the minimum possible.
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out.append((byte) (num >> 16)); // byte 1, count = 0 or 1 or 2
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if (eq_count <= 1) {
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out.append((byte) ((num >> 8) & 0xFF)); // byte 2, count = 0 or 1
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if (eq_count == 0) {
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out.append((byte) (num & 0xFF)); // byte 3, count = 0
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}
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}
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}
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/** Given a sequence of input bytes using the Base64 encoding, produces a
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sequence of unencoded output bytes. Note that some (small) amount of
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buffering may be necessary, if the input byte stream didn't fall on an
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appropriate boundary. If there are bytes in `out' already, the new
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bytes are appended, so the caller should do `out.setLength(0)' first
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if that's desired.
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*/
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public final void translate(ByteBuf in, ByteBuf out) {
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if (token == null) // already saw eof marker?
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return;
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byte inb[] = in.toBytes();
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int in_length = in.length();
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for (int i = 0; i < in_length; i++) {
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byte b = inb[i];
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byte t = map[b];
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if (t != NUL)
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token[token_length++] = b;
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if (t == EOF) {
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eof(out);
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return;
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} else if (token_length == 4) {
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decode_token(out);
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token_length = 0;
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}
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}
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}
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/** Tell the Base64 decoder that no more input data will be forthcoming.
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This may result in output, as a result of flushing the internal buffer.
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This object must not be used again after calling eof(). If there are
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bytes in `out' already, the new bytes are appended, so the caller should
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do `out.setLength(0)' first if that's desired.
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*/
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public final void eof(ByteBuf out) {
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if (token != null && token_length != 0) {
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while (token_length < 4)
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token[token_length++] = '=';
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decode_final_token(out);
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}
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token_length = 0;
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token = null;
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bytes = null;
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}
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}
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