Classes in this File | Line Coverage | Branch Coverage | Complexity | ||||
QuotedPrintableDecoder |
|
| 4.333333333333333;4.333 |
1 | /* | |
2 | * Licensed to the Apache Software Foundation (ASF) under one or more | |
3 | * contributor license agreements. See the NOTICE file distributed with | |
4 | * this work for additional information regarding copyright ownership. | |
5 | * The ASF licenses this file to You under the Apache License, Version 2.0 | |
6 | * (the "License"); you may not use this file except in compliance with | |
7 | * the License. You may obtain a copy of the License at | |
8 | * | |
9 | * http://www.apache.org/licenses/LICENSE-2.0 | |
10 | * | |
11 | * Unless required by applicable law or agreed to in writing, software | |
12 | * distributed under the License is distributed on an "AS IS" BASIS, | |
13 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
14 | * See the License for the specific language governing permissions and | |
15 | * limitations under the License. | |
16 | */ | |
17 | package org.apache.commons.fileupload.util.mime; | |
18 | ||
19 | import java.io.IOException; | |
20 | import java.io.OutputStream; | |
21 | ||
22 | /** | |
23 | * @since 1.3 | |
24 | */ | |
25 | final class QuotedPrintableDecoder { | |
26 | ||
27 | /** | |
28 | * The shift value required to create the upper nibble | |
29 | * from the first of 2 byte values converted from ascii hex. | |
30 | */ | |
31 | private static final int UPPER_NIBBLE_SHIFT = Byte.SIZE / 2; | |
32 | ||
33 | /** | |
34 | * Hidden constructor, this class must not be instantiated. | |
35 | */ | |
36 | 0 | private QuotedPrintableDecoder() { |
37 | // do nothing | |
38 | 0 | } |
39 | ||
40 | /** | |
41 | * Decode the encoded byte data writing it to the given output stream. | |
42 | * | |
43 | * @param data The array of byte data to decode. | |
44 | * @param out The output stream used to return the decoded data. | |
45 | * | |
46 | * @return the number of bytes produced. | |
47 | * @throws IOException | |
48 | */ | |
49 | public static int decode(byte[] data, OutputStream out) throws IOException { | |
50 | 12 | int off = 0; |
51 | 12 | int length = data.length; |
52 | 12 | int endOffset = off + length; |
53 | 12 | int bytesWritten = 0; |
54 | ||
55 | 245 | while (off < endOffset) { |
56 | 238 | byte ch = data[off++]; |
57 | ||
58 | // space characters were translated to '_' on encode, so we need to translate them back. | |
59 | 238 | if (ch == '_') { |
60 | 3 | out.write(' '); |
61 | 235 | } else if (ch == '=') { |
62 | // we found an encoded character. Reduce the 3 char sequence to one. | |
63 | // but first, make sure we have two characters to work with. | |
64 | 27 | if (off + 1 >= endOffset) { |
65 | 2 | throw new IOException("Invalid quoted printable encoding; truncated escape sequence"); |
66 | } | |
67 | ||
68 | 25 | byte b1 = data[off++]; |
69 | 25 | byte b2 = data[off++]; |
70 | ||
71 | // we've found an encoded carriage return. The next char needs to be a newline | |
72 | 25 | if (b1 == '\r') { |
73 | 3 | if (b2 != '\n') { |
74 | 2 | throw new IOException("Invalid quoted printable encoding; CR must be followed by LF"); |
75 | } | |
76 | // this was a soft linebreak inserted by the encoding. We just toss this away | |
77 | // on decode. | |
78 | } else { | |
79 | // this is a hex pair we need to convert back to a single byte. | |
80 | 22 | int c1 = hexToBinary(b1); |
81 | 21 | int c2 = hexToBinary(b2); |
82 | 21 | out.write((c1 << UPPER_NIBBLE_SHIFT) | c2); |
83 | // 3 bytes in, one byte out | |
84 | 21 | bytesWritten++; |
85 | } | |
86 | 22 | } else { |
87 | // simple character, just write it out. | |
88 | 208 | out.write(ch); |
89 | 208 | bytesWritten++; |
90 | } | |
91 | 233 | } |
92 | ||
93 | 7 | return bytesWritten; |
94 | } | |
95 | ||
96 | /** | |
97 | * Convert a hex digit to the binary value it represents. | |
98 | * | |
99 | * @param b the ascii hex byte to convert (0-0, A-F, a-f) | |
100 | * @return the int value of the hex byte, 0-15 | |
101 | * @throws IOException if the byte is not a valid hex digit. | |
102 | */ | |
103 | private static int hexToBinary(final byte b) throws IOException { | |
104 | // CHECKSTYLE IGNORE MagicNumber FOR NEXT 1 LINE | |
105 | 43 | final int i = Character.digit((char) b, 16); |
106 | 43 | if (i == -1) { |
107 | 1 | throw new IOException("Invalid quoted printable encoding: not a valid hex digit: " + b); |
108 | } | |
109 | 42 | return i; |
110 | } | |
111 | ||
112 | } |