1 /*
2 * Copyright (c) 1997, 2017, 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 /*
27 * @(#)BASE64DecoderStream.java 1.8 02/03/27
28 */
29
30
31
32 package com.sun.xml.internal.messaging.saaj.packaging.mime.util;
33
34 import java.io.*;
35
36 /**
37 * This class implements a BASE64 Decoder. It is implemented as
38 * a FilterInputStream, so one can just wrap this class around
39 * any input stream and read bytes from this filter. The decoding
40 * is done as the bytes are read out.
41 *
42 * @author John Mani
43 * @author Bill Shannon
44 */
45
46 public class BASE64DecoderStream extends FilterInputStream {
47 private byte[] buffer; // cache of decoded bytes
48 private int bufsize = 0; // size of the cache
49 private int index = 0; // index into the cache
50
51 /**
52 * Create a BASE64 decoder that decodes the specified input stream
53 * @param in the input stream
54 */
55 public BASE64DecoderStream(InputStream in) {
56 super(in);
57 buffer = new byte[3];
58 }
59
60 /**
61 * Read the next decoded byte from this input stream. The byte
62 * is returned as an <code>int</code> in the range <code>0</code>
63 * to <code>255</code>. If no byte is available because the end of
64 * the stream has been reached, the value <code>-1</code> is returned.
65 * This method blocks until input data is available, the end of the
66 * stream is detected, or an exception is thrown.
67 *
68 * @return next byte of data, or <code>-1</code> if the end of the
69 * stream is reached.
70 * @exception IOException if an I/O error occurs.
71 * @see java.io.FilterInputStream#in
72 */
73 @Override
74 public int read() throws IOException {
75 if (index >= bufsize) {
76 decode(); // Fills up buffer
77 if (bufsize == 0) // buffer is empty
78 return -1;
79 index = 0; // reset index into buffer
80 }
81 return buffer[index++] & 0xff; // Zero off the MSB
82 }
83
84 /**
85 * Reads up to <code>len</code> decoded bytes of data from this input stream
86 * into an array of bytes. This method blocks until some input is
87 * available.
88 * <p>
89 *
90 * @param buf the buffer into which the data is read.
91 * @param off the start offset of the data.
92 * @param len the maximum number of bytes read.
93 * @return the total number of bytes read into the buffer, or
94 * <code>-1</code> if there is no more data because the end of
95 * the stream has been reached.
96 * @exception IOException if an I/O error occurs.
97 */
98 @Override
99 public int read(byte[] buf, int off, int len) throws IOException {
100 int i, c;
101 for (i = 0; i < len; i++) {
102 if ((c = read()) == -1) {
103 if (i == 0) // At end of stream, so we should
104 i = -1; // return -1 , NOT 0.
105 break;
106 }
107 buf[off+i] = (byte)c;
108 }
109
110 return i;
111 }
112
113 /**
114 * Tests if this input stream supports marks. Currently this class
115 * does not support marks
116 */
117 @Override
118 public boolean markSupported() {
119 return false; // Maybe later ..
120 }
121
122 /**
123 * Returns the number of bytes that can be read from this input
124 * stream without blocking. However, this figure is only
125 * a close approximation in case the original encoded stream
126 * contains embedded CRLFs; since the CRLFs are discarded, not decoded
127 */
128 @Override
129 public int available() throws IOException {
130 // This is only an estimate, since in.available()
131 // might include CRLFs too ..
132 return ((in.available() * 3)/4 + (bufsize-index));
133 }
134
135 /**
136 * This character array provides the character to value map
137 * based on RFC1521.
138 */
139 private final static char pem_array[] = {
140 'A','B','C','D','E','F','G','H', // 0
141 'I','J','K','L','M','N','O','P', // 1
142 'Q','R','S','T','U','V','W','X', // 2
143 'Y','Z','a','b','c','d','e','f', // 3
144 'g','h','i','j','k','l','m','n', // 4
145 'o','p','q','r','s','t','u','v', // 5
146 'w','x','y','z','0','1','2','3', // 6
147 '4','5','6','7','8','9','+','/' // 7
148 };
149
150 private final static byte pem_convert_array[] = new byte[256];
151
152 static {
153 for (int i = 0; i < 255; i++)
154 pem_convert_array[i] = -1;
155 for(int i = 0; i < pem_array.length; i++)
156 pem_convert_array[pem_array[i]] = (byte) i;
157 }
158
159 /* The decoder algorithm */
160 private byte[] decode_buffer = new byte[4];
161 private void decode() throws IOException {
162 bufsize = 0;
163 /*
164 * We need 4 valid base64 characters before we start decoding.
165 * We skip anything that's not a valid base64 character (usually
166 * just CRLF).
167 */
168 int got = 0;
169 while (got < 4) {
170 int i = in.read();
171 if (i == -1) {
172 if (got == 0)
173 return; // EOF before any data is ok
174 throw new IOException("Error in encoded stream, got " + got);
175 }
176 if (i >= 0 && i < 256 && i == '=' || pem_convert_array[i] != -1)
177 decode_buffer[got++] = (byte)i;
178 }
179
180 byte a, b;
181 a = pem_convert_array[decode_buffer[0] & 0xff];
182 b = pem_convert_array[decode_buffer[1] & 0xff];
183 // The first decoded byte
184 buffer[bufsize++] = (byte)(((a << 2) & 0xfc) | ((b >>> 4) & 3));
185
186 if (decode_buffer[2] == '=') // End of this BASE64 encoding
187 return;
188 a = b;
189 b = pem_convert_array[decode_buffer[2] & 0xff];
190 // The second decoded byte
191 buffer[bufsize++] = (byte)(((a << 4) & 0xf0) | ((b >>> 2) & 0xf));
192
193 if (decode_buffer[3] == '=') // End of this BASE64 encoding
194 return;
195 a = b;
196 b = pem_convert_array[decode_buffer[3] & 0xff];
197 // The third decoded byte
198 buffer[bufsize++] = (byte)(((a << 6) & 0xc0) | (b & 0x3f));
199 }
200
201 /**
202 * Base64 decode a byte array. No line breaks are allowed.
203 * This method is suitable for short strings, such as those
204 * in the IMAP AUTHENTICATE protocol, but not to decode the
205 * entire content of a MIME part.
206 *
207 * @param inbuf byte array to decode
208 *
209 * @return decoded byte array
210 *
211 * NOTE: inbuf may only contain valid base64 characters.
212 * Whitespace is not ignored.
213 */
214 public static byte[] decode(byte[] inbuf) {
215 int size = (inbuf.length / 4) * 3;
216 if (size == 0)
217 return inbuf;
218
219 if (inbuf[inbuf.length - 1] == '=') {
220 size--;
221 if (inbuf[inbuf.length - 2] == '=')
222 size--;
223 }
224 byte[] outbuf = new byte[size];
225
226 int inpos = 0, outpos = 0;
227 size = inbuf.length;
228 while (size > 0) {
229 byte a, b;
230 a = pem_convert_array[inbuf[inpos++] & 0xff];
231 b = pem_convert_array[inbuf[inpos++] & 0xff];
232 // The first decoded byte
233 outbuf[outpos++] = (byte)(((a << 2) & 0xfc) | ((b >>> 4) & 3));
234
235 if (inbuf[inpos] == '=') // End of this BASE64 encoding
236 return outbuf;
237 a = b;
238 b = pem_convert_array[inbuf[inpos++] & 0xff];
239 // The second decoded byte
240 outbuf[outpos++] = (byte)(((a << 4) & 0xf0) | ((b >>> 2) & 0xf));
241
242 if (inbuf[inpos] == '=') // End of this BASE64 encoding
243 return outbuf;
244 a = b;
245 b = pem_convert_array[inbuf[inpos++] & 0xff];
246 // The third decoded byte
247 outbuf[outpos++] = (byte)(((a << 6) & 0xc0) | (b & 0x3f));
248 size -= 4;
249 }
250 return outbuf;
251 }
252
253 /*** begin TEST program ***
254 public static void main(String argv[]) throws Exception {
255 FileInputStream infile = new FileInputStream(argv[0]);
256 BASE64DecoderStream decoder = new BASE64DecoderStream(infile);
257 int c;
258
259 while ((c = decoder.read()) != -1)
260 System.out.print((char)c);
261 System.out.flush();
262 }
263 *** end TEST program ***/
264 }