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| 1 | /* | ||
| 2 | * Copyright (c) 1995, 2000, 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 | package sun.misc; | ||
| 26 | |||
| 27 | import java.io.OutputStream; | ||
| 28 | import java.io.ByteArrayOutputStream; | ||
| 29 | import java.io.PushbackInputStream; | ||
| 30 | import java.io.PrintStream; | ||
| 31 | import java.io.IOException; | ||
| 32 | |||
| 33 | /** | ||
| 34 | * This class implements a robust character decoder. The decoder will | ||
| 35 | * converted encoded text into binary data. | ||
| 36 | * | ||
| 37 | * The basic encoding unit is a 3 character atom. It encodes two bytes | ||
| 38 | * of data. Bytes are encoded into a 64 character set, the characters | ||
| 39 | * were chosen specifically because they appear in all codesets. | ||
| 40 | * We don't care what their numerical equivalent is because | ||
| 41 | * we use a character array to map them. This is like UUencoding | ||
| 42 | * with the dependency on ASCII removed. | ||
| 43 | * | ||
| 44 | * The three chars that make up an atom are encoded as follows: | ||
| 45 | * <pre> | ||
| 46 | * 00xxxyyy 00axxxxx 00byyyyy | ||
| 47 | * 00 = leading zeros, all values are 0 - 63 | ||
| 48 | * xxxyyy - Top 3 bits of X, Top 3 bits of Y | ||
| 49 | * axxxxx - a = X parity bit, xxxxx lower 5 bits of X | ||
| 50 | * byyyyy - b = Y parity bit, yyyyy lower 5 bits of Y | ||
| 51 | * </pre> | ||
| 52 | * | ||
| 53 | * The atoms are arranged into lines suitable for inclusion into an | ||
| 54 | * email message or text file. The number of bytes that are encoded | ||
| 55 | * per line is 48 which keeps the total line length under 80 chars) | ||
| 56 | * | ||
| 57 | * Each line has the form( | ||
| 58 | * <pre> | ||
| 59 | * *(LLSS)(DDDD)(DDDD)(DDDD)...(CRC) | ||
| 60 | * Where each (xxx) represents a three character atom. | ||
| 61 | * (LLSS) - 8 bit length (high byte), and sequence number | ||
| 62 | * modulo 256; | ||
| 63 | * (DDDD) - Data byte atoms, if length is odd, last data | ||
| 64 | * atom has (DD00) (high byte data, low byte 0) | ||
| 65 | * (CRC) - 16 bit CRC for the line, includes length, | ||
| 66 | * sequence, and all data bytes. If there is a | ||
| 67 | * zero pad byte (odd length) it is _NOT_ | ||
| 68 | * included in the CRC. | ||
| 69 | * </pre> | ||
| 70 | * | ||
| 71 | * If an error is encountered during decoding this class throws a | ||
| 72 | * CEFormatException. The specific detail messages are: | ||
| 73 | * | ||
| 74 | * <pre> | ||
| 75 | * "UCDecoder: High byte parity error." | ||
| 76 | * "UCDecoder: Low byte parity error." | ||
| 77 | * "UCDecoder: Out of sequence line." | ||
| 78 | * "UCDecoder: CRC check failed." | ||
| 79 | * </pre> | ||
| 80 | * | ||
| 81 | * @author Chuck McManis | ||
| 82 | * @see CharacterEncoder | ||
| 83 | * @see UCEncoder | ||
| 84 | */ | ||
| 85 | public class UCDecoder extends CharacterDecoder { | ||
| 86 | |||
| 87 | /** This class encodes two bytes per atom. */ | ||
| 88 | protected int bytesPerAtom() { | ||
| 89 | return (2); | ||
| 90 | } | ||
| 91 | |||
| 92 | /** this class encodes 48 bytes per line */ | ||
| 93 | protected int bytesPerLine() { | ||
| 94 | return (48); | ||
| 95 | } | ||
| 96 | |||
| 97 | /* this is the UCE mapping of 0-63 to characters .. */ | ||
| 98 | private final static byte map_array[] = { | ||
| 99 | // 0 1 2 3 4 5 6 7 | ||
| 100 | (byte)'0',(byte)'1',(byte)'2',(byte)'3',(byte)'4',(byte)'5',(byte)'6',(byte)'7', // 0 | ||
| 101 | (byte)'8',(byte)'9',(byte)'A',(byte)'B',(byte)'C',(byte)'D',(byte)'E',(byte)'F', // 1 | ||
| 102 | (byte)'G',(byte)'H',(byte)'I',(byte)'J',(byte)'K',(byte)'L',(byte)'M',(byte)'N', // 2 | ||
| 103 | (byte)'O',(byte)'P',(byte)'Q',(byte)'R',(byte)'S',(byte)'T',(byte)'U',(byte)'V', // 3 | ||
| 104 | (byte)'W',(byte)'X',(byte)'Y',(byte)'Z',(byte)'a',(byte)'b',(byte)'c',(byte)'d', // 4 | ||
| 105 | (byte)'e',(byte)'f',(byte)'g',(byte)'h',(byte)'i',(byte)'j',(byte)'k',(byte)'l', // 5 | ||
| 106 | (byte)'m',(byte)'n',(byte)'o',(byte)'p',(byte)'q',(byte)'r',(byte)'s',(byte)'t', // 6 | ||
| 107 | (byte)'u',(byte)'v',(byte)'w',(byte)'x',(byte)'y',(byte)'z',(byte)'(',(byte)')' // 7 | ||
| 108 | }; | ||
| 109 | |||
| 110 | private int sequence; | ||
| 111 | private byte tmp[] = new byte[2]; | ||
| 112 | private CRC16 crc = new CRC16(); | ||
| 113 | |||
| 114 | /** | ||
| 115 | * Decode one atom - reads the characters from the input stream, decodes | ||
| 116 | * them, and checks for valid parity. | ||
| 117 | */ | ||
| 118 | protected void decodeAtom(PushbackInputStream inStream, OutputStream outStream, int l) throws IOException { | ||
| 119 | int i, p1, p2, np1, np2; | ||
| 120 | byte a = -1, b = -1, c = -1; | ||
| 121 | byte high_byte, low_byte; | ||
| 122 | byte tmp[] = new byte[3]; | ||
| 123 | |||
| 124 | i = inStream.read(tmp); | ||
| 125 | if (i != 3) { | ||
| 126 | throw new CEStreamExhausted(); | ||
| 127 | } | ||
| 128 | for (i = 0; (i < 64) && ((a == -1) || (b == -1) || (c == -1)); i++) { | ||
| 129 | if (tmp[0] == map_array[i]) { | ||
| 130 | a = (byte) i; | ||
| 131 | } | ||
| 132 | if (tmp[1] == map_array[i]) { | ||
| 133 | b = (byte) i; | ||
| 134 | } | ||
| 135 | if (tmp[2] == map_array[i]) { | ||
| 136 | c = (byte) i; | ||
| 137 | } | ||
| 138 | } | ||
| 139 | high_byte = (byte) (((a & 0x38) << 2) + (b & 0x1f)); | ||
| 140 | low_byte = (byte) (((a & 0x7) << 5) + (c & 0x1f)); | ||
| 141 | p1 = 0; | ||
| 142 | p2 = 0; | ||
| 143 | for (i = 1; i < 256; i = i * 2) { | ||
| 144 | if ((high_byte & i) != 0) | ||
| 145 | p1++; | ||
| 146 | if ((low_byte & i) != 0) | ||
| 147 | p2++; | ||
| 148 | } | ||
| 149 | np1 = (b & 32) / 32; | ||
| 150 | np2 = (c & 32) / 32; | ||
| 151 | if ((p1 & 1) != np1) { | ||
| 152 | throw new CEFormatException("UCDecoder: High byte parity error."); | ||
| 153 | } | ||
| 154 | if ((p2 & 1) != np2) { | ||
| 155 | throw new CEFormatException("UCDecoder: Low byte parity error."); | ||
| 156 | } | ||
| 157 | outStream.write(high_byte); | ||
| 158 | crc.update(high_byte); | ||
| 159 | if (l == 2) { | ||
| 160 | outStream.write(low_byte); | ||
| 161 | crc.update(low_byte); | ||
| 162 | } | ||
| 163 | } | ||
| 164 | |||
| 165 | private ByteArrayOutputStream lineAndSeq = new ByteArrayOutputStream(2); | ||
| 166 | |||
| 167 | /** | ||
| 168 | * decodeBufferPrefix initializes the sequence number to zero. | ||
| 169 | */ | ||
| 170 | protected void decodeBufferPrefix(PushbackInputStream inStream, OutputStream outStream) { | ||
| 171 | sequence = 0; | ||
| 172 | } | ||
| 173 | |||
| 174 | /** | ||
| 175 | * decodeLinePrefix reads the sequence number and the number of | ||
| 176 | * encoded bytes from the line. If the sequence number is not the | ||
| 177 | * previous sequence number + 1 then an exception is thrown. | ||
| 178 | * UCE lines are line terminator immune, they all start with * | ||
| 179 | * so the other thing this method does is scan for the next line | ||
| 180 | * by looking for the * character. | ||
| 181 | * | ||
| 182 | * @exception CEFormatException out of sequence lines detected. | ||
| 183 | */ | ||
| 184 | protected int decodeLinePrefix(PushbackInputStream inStream, OutputStream outStream) throws IOException { | ||
| 185 | int i; | ||
| 186 | int nLen, nSeq; | ||
| 187 | byte xtmp[]; | ||
| 188 | int c; | ||
| 189 | |||
| 190 | crc.value = 0; | ||
| 191 | while (true) { | ||
| 192 | c = inStream.read(tmp, 0, 1); | ||
| 193 | if (c == -1) { | ||
| 194 | throw new CEStreamExhausted(); | ||
| 195 | } | ||
| 196 | if (tmp[0] == '*') { | ||
| 197 | break; | ||
| 198 | } | ||
| 199 | } | ||
| 200 | lineAndSeq.reset(); | ||
| 201 | decodeAtom(inStream, lineAndSeq, 2); | ||
| 202 | xtmp = lineAndSeq.toByteArray(); | ||
| 203 | nLen = xtmp[0] & 0xff; | ||
| 204 | nSeq = xtmp[1] & 0xff; | ||
| 205 | if (nSeq != sequence) { | ||
| 206 | throw new CEFormatException("UCDecoder: Out of sequence line."); | ||
| 207 | } | ||
| 208 | sequence = (sequence + 1) & 0xff; | ||
| 209 | return (nLen); | ||
| 210 | } | ||
| 211 | |||
| 212 | |||
| 213 | /** | ||
| 214 | * this method reads the CRC that is at the end of every line and | ||
| 215 | * verifies that it matches the computed CRC. | ||
| 216 | * | ||
| 217 | * @exception CEFormatException if CRC check fails. | ||
| 218 | */ | ||
| 219 | protected void decodeLineSuffix(PushbackInputStream inStream, OutputStream outStream) throws IOException { | ||
| 220 | int i; | ||
| 221 | int lineCRC = crc.value; | ||
| 222 | int readCRC; | ||
| 223 | byte tmp[]; | ||
| 224 | |||
| 225 | lineAndSeq.reset(); | ||
| 226 | decodeAtom(inStream, lineAndSeq, 2); | ||
| 227 | tmp = lineAndSeq.toByteArray(); | ||
| 228 | readCRC = ((tmp[0] << 8) & 0xFF00) + (tmp[1] & 0xff); | ||
| 229 | if (readCRC != lineCRC) { | ||
| 230 | throw new CEFormatException("UCDecoder: CRC check failed."); | ||
| 231 | } | ||
| 232 | } | ||
| 233 | } | ||