1 /* |
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2 * Copyright (c) 1995, 2011, Oracle and/or its affiliates. All rights reserved. |
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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4 * |
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5 * This code is free software; you can redistribute it and/or modify it |
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6 * under the terms of the GNU General Public License version 2 only, as |
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7 * published by the Free Software Foundation. Oracle designates this |
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8 * particular file as subject to the "Classpath" exception as provided |
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9 * by Oracle in the LICENSE file that accompanied this code. |
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10 * |
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11 * This code is distributed in the hope that it will be useful, but WITHOUT |
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12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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14 * version 2 for more details (a copy is included in the LICENSE file that |
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15 * accompanied this code). |
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16 * |
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17 * You should have received a copy of the GNU General Public License version |
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18 * 2 along with this work; if not, write to the Free Software Foundation, |
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19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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20 * |
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21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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22 * or visit www.oracle.com if you need additional information or have any |
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23 * questions. |
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24 */ |
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25 package sun.misc; |
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26 |
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27 import java.io.OutputStream; |
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28 import java.io.PushbackInputStream; |
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29 import java.io.PrintStream; |
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30 |
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31 /** |
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32 * This class implements a BASE64 Character decoder as specified in RFC1521. |
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33 * |
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34 * This RFC is part of the MIME specification which is published by the |
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35 * Internet Engineering Task Force (IETF). Unlike some other encoding |
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36 * schemes there is nothing in this encoding that tells the decoder |
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37 * where a buffer starts or stops, so to use it you will need to isolate |
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38 * your encoded data into a single chunk and then feed them this decoder. |
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39 * The simplest way to do that is to read all of the encoded data into a |
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40 * string and then use: |
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41 * <pre> |
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42 * byte mydata[]; |
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43 * BASE64Decoder base64 = new BASE64Decoder(); |
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44 * |
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45 * mydata = base64.decodeBuffer(bufferString); |
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46 * </pre> |
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47 * This will decode the String in <i>bufferString</i> and give you an array |
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48 * of bytes in the array <i>myData</i>. |
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49 * |
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50 * On errors, this class throws a CEFormatException with the following detail |
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51 * strings: |
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52 * <pre> |
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53 * "BASE64Decoder: Not enough bytes for an atom." |
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54 * </pre> |
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55 * |
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56 * @author Chuck McManis |
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57 * @see CharacterEncoder |
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58 * @see BASE64Decoder |
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59 */ |
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60 |
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61 public class BASE64Decoder extends CharacterDecoder { |
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62 |
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63 /** This class has 4 bytes per atom */ |
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64 protected int bytesPerAtom() { |
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65 return (4); |
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66 } |
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67 |
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68 /** Any multiple of 4 will do, 72 might be common */ |
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69 protected int bytesPerLine() { |
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70 return (72); |
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71 } |
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72 |
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73 /** |
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74 * This character array provides the character to value map |
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75 * based on RFC1521. |
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76 */ |
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77 private static final char pem_array[] = { |
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78 // 0 1 2 3 4 5 6 7 |
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79 'A','B','C','D','E','F','G','H', // 0 |
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80 'I','J','K','L','M','N','O','P', // 1 |
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81 'Q','R','S','T','U','V','W','X', // 2 |
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82 'Y','Z','a','b','c','d','e','f', // 3 |
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83 'g','h','i','j','k','l','m','n', // 4 |
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84 'o','p','q','r','s','t','u','v', // 5 |
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85 'w','x','y','z','0','1','2','3', // 6 |
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86 '4','5','6','7','8','9','+','/' // 7 |
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87 }; |
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88 |
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89 private static final byte pem_convert_array[] = new byte[256]; |
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90 |
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91 static { |
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92 for (int i = 0; i < 255; i++) { |
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93 pem_convert_array[i] = -1; |
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94 } |
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95 for (int i = 0; i < pem_array.length; i++) { |
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96 pem_convert_array[pem_array[i]] = (byte) i; |
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97 } |
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98 } |
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99 |
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100 byte decode_buffer[] = new byte[4]; |
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101 |
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102 /** |
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103 * Decode one BASE64 atom into 1, 2, or 3 bytes of data. |
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104 */ |
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105 @SuppressWarnings("fallthrough") |
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106 protected void decodeAtom(PushbackInputStream inStream, OutputStream outStream, int rem) |
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107 throws java.io.IOException |
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108 { |
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109 int i; |
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110 byte a = -1, b = -1, c = -1, d = -1; |
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111 |
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112 if (rem < 2) { |
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113 throw new CEFormatException("BASE64Decoder: Not enough bytes for an atom."); |
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114 } |
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115 do { |
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116 i = inStream.read(); |
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117 if (i == -1) { |
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118 throw new CEStreamExhausted(); |
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119 } |
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120 } while (i == '\n' || i == '\r'); |
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121 decode_buffer[0] = (byte) i; |
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122 |
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123 i = readFully(inStream, decode_buffer, 1, rem-1); |
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124 if (i == -1) { |
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125 throw new CEStreamExhausted(); |
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126 } |
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127 |
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128 if (rem > 3 && decode_buffer[3] == '=') { |
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129 rem = 3; |
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130 } |
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131 if (rem > 2 && decode_buffer[2] == '=') { |
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132 rem = 2; |
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133 } |
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134 switch (rem) { |
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135 case 4: |
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136 d = pem_convert_array[decode_buffer[3] & 0xff]; |
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137 // NOBREAK |
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138 case 3: |
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139 c = pem_convert_array[decode_buffer[2] & 0xff]; |
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140 // NOBREAK |
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141 case 2: |
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142 b = pem_convert_array[decode_buffer[1] & 0xff]; |
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143 a = pem_convert_array[decode_buffer[0] & 0xff]; |
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144 break; |
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145 } |
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146 |
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147 switch (rem) { |
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148 case 2: |
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149 outStream.write( (byte)(((a << 2) & 0xfc) | ((b >>> 4) & 3)) ); |
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150 break; |
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151 case 3: |
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152 outStream.write( (byte) (((a << 2) & 0xfc) | ((b >>> 4) & 3)) ); |
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153 outStream.write( (byte) (((b << 4) & 0xf0) | ((c >>> 2) & 0xf)) ); |
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154 break; |
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155 case 4: |
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156 outStream.write( (byte) (((a << 2) & 0xfc) | ((b >>> 4) & 3)) ); |
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157 outStream.write( (byte) (((b << 4) & 0xf0) | ((c >>> 2) & 0xf)) ); |
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158 outStream.write( (byte) (((c << 6) & 0xc0) | (d & 0x3f)) ); |
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159 break; |
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160 } |
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161 return; |
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162 } |
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163 } |
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