1 /* 2 * Copyright (c) 1995, 2011, 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.PushbackInputStream; 29 import java.io.PrintStream; 30 31 /** 32 * This class implements a BASE64 Character decoder as specified in RFC1521. 33 * 34 * This RFC is part of the MIME specification which is published by the 35 * Internet Engineering Task Force (IETF). Unlike some other encoding 36 * schemes there is nothing in this encoding that tells the decoder 37 * where a buffer starts or stops, so to use it you will need to isolate 38 * your encoded data into a single chunk and then feed them this decoder. 39 * The simplest way to do that is to read all of the encoded data into a 40 * string and then use: 41 * <pre> 42 * byte mydata[]; 43 * BASE64Decoder base64 = new BASE64Decoder(); 44 * 45 * mydata = base64.decodeBuffer(bufferString); 46 * </pre> 47 * This will decode the String in <i>bufferString</i> and give you an array 48 * of bytes in the array <i>myData</i>. 49 * 50 * On errors, this class throws a CEFormatException with the following detail 51 * strings: 52 * <pre> 53 * "BASE64Decoder: Not enough bytes for an atom." 54 * </pre> 55 * 56 * @author Chuck McManis 57 * @see CharacterEncoder 58 * @see BASE64Decoder 59 */ 60 61 public class BASE64Decoder extends CharacterDecoder { 62 63 /** This class has 4 bytes per atom */ bytesPerAtom()64 protected int bytesPerAtom() { 65 return (4); 66 } 67 68 /** Any multiple of 4 will do, 72 might be common */ bytesPerLine()69 protected int bytesPerLine() { 70 return (72); 71 } 72 73 /** 74 * This character array provides the character to value map 75 * based on RFC1521. 76 */ 77 private final static char pem_array[] = { 78 // 0 1 2 3 4 5 6 7 79 'A','B','C','D','E','F','G','H', // 0 80 'I','J','K','L','M','N','O','P', // 1 81 'Q','R','S','T','U','V','W','X', // 2 82 'Y','Z','a','b','c','d','e','f', // 3 83 'g','h','i','j','k','l','m','n', // 4 84 'o','p','q','r','s','t','u','v', // 5 85 'w','x','y','z','0','1','2','3', // 6 86 '4','5','6','7','8','9','+','/' // 7 87 }; 88 89 private final static byte pem_convert_array[] = new byte[256]; 90 91 static { 92 for (int i = 0; i < 255; i++) { 93 pem_convert_array[i] = -1; 94 } 95 for (int i = 0; i < pem_array.length; i++) { 96 pem_convert_array[pem_array[i]] = (byte) i; 97 } 98 } 99 100 byte decode_buffer[] = new byte[4]; 101 102 /** 103 * Decode one BASE64 atom into 1, 2, or 3 bytes of data. 104 */ 105 @SuppressWarnings("fallthrough") decodeAtom(PushbackInputStream inStream, OutputStream outStream, int rem)106 protected void decodeAtom(PushbackInputStream inStream, OutputStream outStream, int rem) 107 throws java.io.IOException 108 { 109 int i; 110 byte a = -1, b = -1, c = -1, d = -1; 111 112 if (rem < 2) { 113 throw new CEFormatException("BASE64Decoder: Not enough bytes for an atom."); 114 } 115 do { 116 i = inStream.read(); 117 if (i == -1) { 118 throw new CEStreamExhausted(); 119 } 120 } while (i == '\n' || i == '\r'); 121 decode_buffer[0] = (byte) i; 122 123 i = readFully(inStream, decode_buffer, 1, rem-1); 124 if (i == -1) { 125 throw new CEStreamExhausted(); 126 } 127 128 if (rem > 3 && decode_buffer[3] == '=') { 129 rem = 3; 130 } 131 if (rem > 2 && decode_buffer[2] == '=') { 132 rem = 2; 133 } 134 switch (rem) { 135 case 4: 136 d = pem_convert_array[decode_buffer[3] & 0xff]; 137 // NOBREAK 138 case 3: 139 c = pem_convert_array[decode_buffer[2] & 0xff]; 140 // NOBREAK 141 case 2: 142 b = pem_convert_array[decode_buffer[1] & 0xff]; 143 a = pem_convert_array[decode_buffer[0] & 0xff]; 144 break; 145 } 146 147 switch (rem) { 148 case 2: 149 outStream.write( (byte)(((a << 2) & 0xfc) | ((b >>> 4) & 3)) ); 150 break; 151 case 3: 152 outStream.write( (byte) (((a << 2) & 0xfc) | ((b >>> 4) & 3)) ); 153 outStream.write( (byte) (((b << 4) & 0xf0) | ((c >>> 2) & 0xf)) ); 154 break; 155 case 4: 156 outStream.write( (byte) (((a << 2) & 0xfc) | ((b >>> 4) & 3)) ); 157 outStream.write( (byte) (((b << 4) & 0xf0) | ((c >>> 2) & 0xf)) ); 158 outStream.write( (byte) (((c << 6) & 0xc0) | (d & 0x3f)) ); 159 break; 160 } 161 return; 162 } 163 } 164