| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.commons.fileupload.util.mime; |
| |
| import java.io.IOException; |
| import java.io.OutputStream; |
| |
| /** |
| * @since 1.3 |
| */ |
| final class QuotedPrintableDecoder { |
| |
| /** |
| * Set up the encoding table. |
| */ |
| private static final byte[] ENCODING_TABLE = { |
| (byte) '0', (byte) '1', (byte) '2', (byte) '3', (byte) '4', (byte) '5', (byte) '6', (byte) '7', |
| (byte) '8', (byte) '9', (byte) 'A', (byte) 'B', (byte) 'C', (byte) 'D', (byte) 'E', (byte) 'F' |
| }; |
| |
| /** |
| * The shift value required to create the upper nibble |
| * from the first of 2 byte values converted from ascii hex. |
| */ |
| private static final int UPPER_NIBBLE_SHIFT = Byte.SIZE / 2; |
| |
| /** |
| * Set up the decoding table; this is indexed by a byte converted to an int, |
| * so must be at least as large as the number of different byte values, |
| * positive and negative and zero. |
| */ |
| private static final byte[] DECODING_TABLE = new byte[Byte.MAX_VALUE - Byte.MIN_VALUE + 1]; |
| |
| static { |
| // initialize the decoding table |
| for (int i = 0; i < ENCODING_TABLE.length; i++) { |
| DECODING_TABLE[ENCODING_TABLE[i]] = (byte) i; |
| } |
| } |
| |
| /** |
| * Hidden constructor, this class must not be instantiated. |
| */ |
| private QuotedPrintableDecoder() { |
| // do nothing |
| } |
| |
| /** |
| * Decode the encoded byte data writing it to the given output stream. |
| * |
| * @param data The array of byte data to decode. |
| * @param out The output stream used to return the decoded data. |
| * |
| * @return the number of bytes produced. |
| * @exception IOException |
| */ |
| public static int decode(byte[] data, OutputStream out) throws IOException { |
| int off = 0; |
| int length = data.length; |
| int endOffset = off + length; |
| int bytesWritten = 0; |
| |
| while (off < endOffset) { |
| byte ch = data[off++]; |
| |
| // space characters were translated to '_' on encode, so we need to translate them back. |
| if (ch == '_') { |
| out.write(' '); |
| } else if (ch == '=') { |
| // we found an encoded character. Reduce the 3 char sequence to one. |
| // but first, make sure we have two characters to work with. |
| if (off + 1 >= endOffset) { |
| throw new IOException("Invalid quoted printable encoding"); |
| } |
| // convert the two bytes back from hex. |
| byte b1 = data[off++]; |
| byte b2 = data[off++]; |
| |
| // we've found an encoded carriage return. The next char needs to be a newline |
| if (b1 == '\r') { |
| if (b2 != '\n') { |
| throw new IOException("Invalid quoted printable encoding"); |
| } |
| // this was a soft linebreak inserted by the encoding. We just toss this away |
| // on decode. |
| } else { |
| // this is a hex pair we need to convert back to a single byte. |
| byte c1 = DECODING_TABLE[b1]; |
| byte c2 = DECODING_TABLE[b2]; |
| out.write((c1 << UPPER_NIBBLE_SHIFT) | c2); |
| // 3 bytes in, one byte out |
| bytesWritten++; |
| } |
| } else { |
| // simple character, just write it out. |
| out.write(ch); |
| bytesWritten++; |
| } |
| } |
| |
| return bytesWritten; |
| } |
| |
| } |