[6785] | 1 | /**************************************************************** |
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| 2 | * Licensed to the Apache Software Foundation (ASF) under one * |
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| 3 | * or more contributor license agreements. See the NOTICE file * |
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| 4 | * distributed with this work for additional information * |
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| 5 | * regarding copyright ownership. The ASF licenses this file * |
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| 6 | * to you under the Apache License, Version 2.0 (the * |
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| 7 | * "License"); you may not use this file except in compliance * |
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| 8 | * with the License. You may obtain a copy of the License at * |
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| 9 | * * |
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| 10 | * http://www.apache.org/licenses/LICENSE-2.0 * |
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| 11 | * * |
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| 12 | * Unless required by applicable law or agreed to in writing, * |
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| 13 | * software distributed under the License is distributed on an * |
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| 14 | * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY * |
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| 15 | * KIND, either express or implied. See the License for the * |
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| 16 | * specific language governing permissions and limitations * |
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| 17 | * under the License. * |
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| 18 | ****************************************************************/ |
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| 19 | |
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| 20 | package org.apache.james.mime4j.codec; |
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| 21 | |
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| 22 | import java.io.IOException; |
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| 23 | import java.io.InputStream; |
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| 24 | |
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| 25 | import org.apache.james.mime4j.util.ByteArrayBuffer; |
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| 26 | |
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| 27 | /** |
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| 28 | * Performs Base-64 decoding on an underlying stream. |
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| 29 | */ |
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| 30 | public class Base64InputStream extends InputStream { |
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| 31 | private static final int ENCODED_BUFFER_SIZE = 1536; |
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| 32 | |
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| 33 | private static final int[] BASE64_DECODE = new int[256]; |
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| 34 | |
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| 35 | static { |
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| 36 | for (int i = 0; i < 256; i++) |
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| 37 | BASE64_DECODE[i] = -1; |
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| 38 | for (int i = 0; i < Base64OutputStream.BASE64_TABLE.length; i++) |
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| 39 | BASE64_DECODE[Base64OutputStream.BASE64_TABLE[i] & 0xff] = i; |
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| 40 | } |
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| 41 | |
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| 42 | private static final byte BASE64_PAD = '='; |
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| 43 | |
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| 44 | private static final int EOF = -1; |
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| 45 | |
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| 46 | private final byte[] singleByte = new byte[1]; |
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| 47 | |
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| 48 | private final InputStream in; |
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| 49 | private final byte[] encoded; |
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| 50 | private final ByteArrayBuffer decodedBuf; |
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| 51 | |
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| 52 | private int position = 0; // current index into encoded buffer |
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| 53 | private int size = 0; // current size of encoded buffer |
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| 54 | |
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| 55 | private boolean closed = false; |
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| 56 | private boolean eof; // end of file or pad character reached |
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| 57 | |
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| 58 | private final DecodeMonitor monitor; |
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| 59 | |
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| 60 | public Base64InputStream(InputStream in, DecodeMonitor monitor) { |
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| 61 | this(ENCODED_BUFFER_SIZE, in, monitor); |
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| 62 | } |
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| 63 | |
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| 64 | protected Base64InputStream(int bufsize, InputStream in, DecodeMonitor monitor) { |
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| 65 | if (in == null) |
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| 66 | throw new IllegalArgumentException(); |
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| 67 | this.encoded = new byte[bufsize]; |
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| 68 | this.decodedBuf = new ByteArrayBuffer(512); |
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| 69 | this.in = in; |
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| 70 | this.monitor = monitor; |
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| 71 | } |
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| 72 | |
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| 73 | public Base64InputStream(InputStream in) { |
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| 74 | this(in, false); |
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| 75 | } |
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| 76 | |
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| 77 | public Base64InputStream(InputStream in, boolean strict) { |
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| 78 | this(ENCODED_BUFFER_SIZE, in, strict ? DecodeMonitor.STRICT : DecodeMonitor.SILENT); |
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| 79 | } |
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| 80 | |
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| 81 | @Override |
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| 82 | public int read() throws IOException { |
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| 83 | if (closed) |
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| 84 | throw new IOException("Stream has been closed"); |
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| 85 | |
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| 86 | while (true) { |
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| 87 | int bytes = read0(singleByte, 0, 1); |
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| 88 | if (bytes == EOF) |
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| 89 | return EOF; |
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| 90 | |
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| 91 | if (bytes == 1) |
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| 92 | return singleByte[0] & 0xff; |
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| 93 | } |
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| 94 | } |
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| 95 | |
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| 96 | @Override |
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| 97 | public int read(byte[] buffer) throws IOException { |
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| 98 | if (closed) |
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| 99 | throw new IOException("Stream has been closed"); |
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| 100 | |
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| 101 | if (buffer == null) |
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| 102 | throw new NullPointerException(); |
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| 103 | |
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| 104 | if (buffer.length == 0) |
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| 105 | return 0; |
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| 106 | |
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| 107 | return read0(buffer, 0, buffer.length); |
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| 108 | } |
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| 109 | |
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| 110 | @Override |
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| 111 | public int read(byte[] buffer, int offset, int length) throws IOException { |
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| 112 | if (closed) |
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| 113 | throw new IOException("Stream has been closed"); |
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| 114 | |
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| 115 | if (buffer == null) |
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| 116 | throw new NullPointerException(); |
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| 117 | |
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| 118 | if (offset < 0 || length < 0 || offset + length > buffer.length) |
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| 119 | throw new IndexOutOfBoundsException(); |
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| 120 | |
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| 121 | if (length == 0) |
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| 122 | return 0; |
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| 123 | |
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| 124 | return read0(buffer, offset, length); |
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| 125 | } |
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| 126 | |
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| 127 | @Override |
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| 128 | public void close() throws IOException { |
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| 129 | if (closed) |
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| 130 | return; |
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| 131 | |
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| 132 | closed = true; |
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| 133 | } |
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| 134 | |
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| 135 | private int read0(final byte[] buffer, final int off, final int len) throws IOException { |
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| 136 | int from = off; |
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| 137 | int to = off + len; |
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| 138 | int index = off; |
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| 139 | |
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| 140 | // check if a previous invocation left decoded content |
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| 141 | if (decodedBuf.length() > 0) { |
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| 142 | int chunk = Math.min(decodedBuf.length(), len); |
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| 143 | System.arraycopy(decodedBuf.buffer(), 0, buffer, index, chunk); |
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| 144 | decodedBuf.remove(0, chunk); |
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| 145 | index += chunk; |
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| 146 | } |
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| 147 | |
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| 148 | // eof or pad reached? |
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| 149 | |
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| 150 | if (eof) |
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| 151 | return index == from ? EOF : index - from; |
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| 152 | |
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| 153 | // decode into given buffer |
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| 154 | |
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| 155 | int data = 0; // holds decoded data; up to four sextets |
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| 156 | int sextets = 0; // number of sextets |
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| 157 | |
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| 158 | while (index < to) { |
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| 159 | // make sure buffer not empty |
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| 160 | |
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| 161 | while (position == size) { |
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| 162 | int n = in.read(encoded, 0, encoded.length); |
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| 163 | if (n == EOF) { |
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| 164 | eof = true; |
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| 165 | |
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| 166 | if (sextets != 0) { |
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| 167 | // error in encoded data |
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| 168 | handleUnexpectedEof(sextets); |
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| 169 | } |
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| 170 | |
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| 171 | return index == from ? EOF : index - from; |
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| 172 | } else if (n > 0) { |
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| 173 | position = 0; |
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| 174 | size = n; |
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| 175 | } else { |
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| 176 | assert n == 0; |
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| 177 | } |
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| 178 | } |
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| 179 | |
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| 180 | // decode buffer |
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| 181 | |
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| 182 | while (position < size && index < to) { |
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| 183 | int value = encoded[position++] & 0xff; |
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| 184 | |
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| 185 | if (value == BASE64_PAD) { |
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| 186 | index = decodePad(data, sextets, buffer, index, to); |
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| 187 | return index - from; |
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| 188 | } |
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| 189 | |
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| 190 | int decoded = BASE64_DECODE[value]; |
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| 191 | if (decoded < 0) { // -1: not a base64 char |
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| 192 | if (value != 0x0D && value != 0x0A && value != 0x20) { |
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| 193 | if (monitor.warn("Unexpected base64 byte: "+(byte) value, "ignoring.")) |
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| 194 | throw new IOException("Unexpected base64 byte"); |
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| 195 | } |
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| 196 | continue; |
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| 197 | } |
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| 198 | |
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| 199 | data = (data << 6) | decoded; |
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| 200 | sextets++; |
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| 201 | |
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| 202 | if (sextets == 4) { |
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| 203 | sextets = 0; |
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| 204 | |
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| 205 | byte b1 = (byte) (data >>> 16); |
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| 206 | byte b2 = (byte) (data >>> 8); |
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| 207 | byte b3 = (byte) data; |
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| 208 | |
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| 209 | if (index < to - 2) { |
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| 210 | buffer[index++] = b1; |
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| 211 | buffer[index++] = b2; |
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| 212 | buffer[index++] = b3; |
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| 213 | } else { |
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| 214 | if (index < to - 1) { |
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| 215 | buffer[index++] = b1; |
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| 216 | buffer[index++] = b2; |
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| 217 | decodedBuf.append(b3); |
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| 218 | } else if (index < to) { |
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| 219 | buffer[index++] = b1; |
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| 220 | decodedBuf.append(b2); |
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| 221 | decodedBuf.append(b3); |
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| 222 | } else { |
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| 223 | decodedBuf.append(b1); |
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| 224 | decodedBuf.append(b2); |
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| 225 | decodedBuf.append(b3); |
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| 226 | } |
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| 227 | |
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| 228 | assert index == to; |
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| 229 | return to - from; |
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| 230 | } |
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| 231 | } |
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| 232 | } |
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| 233 | } |
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| 234 | |
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| 235 | assert sextets == 0; |
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| 236 | assert index == to; |
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| 237 | return to - from; |
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| 238 | } |
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| 239 | |
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| 240 | private int decodePad(int data, int sextets, final byte[] buffer, |
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| 241 | int index, final int end) throws IOException { |
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| 242 | eof = true; |
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| 243 | |
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| 244 | if (sextets == 2) { |
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| 245 | // one byte encoded as "XY==" |
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| 246 | |
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| 247 | byte b = (byte) (data >>> 4); |
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| 248 | if (index < end) { |
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| 249 | buffer[index++] = b; |
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| 250 | } else { |
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| 251 | decodedBuf.append(b); |
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| 252 | } |
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| 253 | } else if (sextets == 3) { |
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| 254 | // two bytes encoded as "XYZ=" |
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| 255 | |
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| 256 | byte b1 = (byte) (data >>> 10); |
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| 257 | byte b2 = (byte) ((data >>> 2) & 0xFF); |
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| 258 | |
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| 259 | if (index < end - 1) { |
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| 260 | buffer[index++] = b1; |
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| 261 | buffer[index++] = b2; |
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| 262 | } else if (index < end) { |
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| 263 | buffer[index++] = b1; |
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| 264 | decodedBuf.append(b2); |
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| 265 | } else { |
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| 266 | decodedBuf.append(b1); |
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| 267 | decodedBuf.append(b2); |
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| 268 | } |
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| 269 | } else { |
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| 270 | // error in encoded data |
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| 271 | handleUnexpecedPad(sextets); |
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| 272 | } |
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| 273 | |
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| 274 | return index; |
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| 275 | } |
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| 276 | |
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| 277 | private void handleUnexpectedEof(int sextets) throws IOException { |
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| 278 | if (monitor.warn("Unexpected end of BASE64 stream", "dropping " + sextets + " sextet(s)")) |
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| 279 | throw new IOException("Unexpected end of BASE64 stream"); |
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| 280 | } |
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| 281 | |
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| 282 | private void handleUnexpecedPad(int sextets) throws IOException { |
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| 283 | if (monitor.warn("Unexpected padding character", "dropping " + sextets + " sextet(s)")) |
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| 284 | throw new IOException("Unexpected padding character"); |
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| 285 | } |
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| 286 | } |
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