[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.ByteArrayInputStream; |
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| 23 | import java.io.ByteArrayOutputStream; |
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| 24 | import java.io.IOException; |
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| 25 | import java.io.UnsupportedEncodingException; |
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| 26 | import java.nio.charset.Charset; |
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| 27 | import java.util.regex.Matcher; |
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| 28 | import java.util.regex.Pattern; |
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| 29 | |
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| 30 | import org.apache.james.mime4j.util.CharsetUtil; |
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| 31 | |
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| 32 | /** |
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| 33 | * Static methods for decoding strings, byte arrays and encoded words. |
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| 34 | */ |
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| 35 | public class DecoderUtil { |
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| 36 | |
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| 37 | private static final Pattern PATTERN_ENCODED_WORD = Pattern.compile( |
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| 38 | "(.*?)=\\?([^\\?]+?)\\?(\\w)\\?([^\\?]+?)\\?=", Pattern.DOTALL); |
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| 39 | |
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| 40 | /** |
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| 41 | * Decodes a string containing quoted-printable encoded data. |
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| 42 | * |
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| 43 | * @param s the string to decode. |
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| 44 | * @return the decoded bytes. |
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| 45 | */ |
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| 46 | private static byte[] decodeQuotedPrintable(String s, DecodeMonitor monitor) { |
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| 47 | ByteArrayOutputStream baos = new ByteArrayOutputStream(); |
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| 48 | |
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| 49 | try { |
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| 50 | byte[] bytes = s.getBytes("US-ASCII"); |
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| 51 | |
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| 52 | QuotedPrintableInputStream is = new QuotedPrintableInputStream( |
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| 53 | new ByteArrayInputStream(bytes), monitor); |
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| 54 | |
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| 55 | int b = 0; |
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| 56 | while ((b = is.read()) != -1) { |
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| 57 | baos.write(b); |
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| 58 | } |
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| 59 | } catch (IOException e) { |
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| 60 | // This should never happen! |
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| 61 | throw new IllegalStateException(e); |
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| 62 | } |
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| 63 | |
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| 64 | return baos.toByteArray(); |
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| 65 | } |
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| 66 | |
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| 67 | /** |
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| 68 | * Decodes a string containing base64 encoded data. |
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| 69 | * |
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| 70 | * @param s the string to decode. |
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| 71 | * @param monitor |
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| 72 | * @return the decoded bytes. |
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| 73 | */ |
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| 74 | private static byte[] decodeBase64(String s, DecodeMonitor monitor) { |
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| 75 | ByteArrayOutputStream baos = new ByteArrayOutputStream(); |
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| 76 | |
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| 77 | try { |
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| 78 | byte[] bytes = s.getBytes("US-ASCII"); |
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| 79 | |
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| 80 | Base64InputStream is = new Base64InputStream( |
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| 81 | new ByteArrayInputStream(bytes), monitor); |
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| 82 | |
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| 83 | int b = 0; |
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| 84 | while ((b = is.read()) != -1) { |
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| 85 | baos.write(b); |
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| 86 | } |
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| 87 | } catch (IOException e) { |
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| 88 | // This should never happen! |
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| 89 | throw new IllegalStateException(e); |
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| 90 | } |
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| 91 | |
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| 92 | return baos.toByteArray(); |
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| 93 | } |
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| 94 | |
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| 95 | /** |
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| 96 | * Decodes an encoded text encoded with the 'B' encoding (described in |
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| 97 | * RFC 2047) found in a header field body. |
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| 98 | * |
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| 99 | * @param encodedText the encoded text to decode. |
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| 100 | * @param charset the Java charset to use. |
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| 101 | * @param monitor |
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| 102 | * @return the decoded string. |
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| 103 | * @throws UnsupportedEncodingException if the given Java charset isn't |
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| 104 | * supported. |
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| 105 | */ |
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| 106 | static String decodeB(String encodedText, String charset, DecodeMonitor monitor) |
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| 107 | throws UnsupportedEncodingException { |
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| 108 | byte[] decodedBytes = decodeBase64(encodedText, monitor); |
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| 109 | return new String(decodedBytes, charset); |
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| 110 | } |
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| 111 | |
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| 112 | /** |
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| 113 | * Decodes an encoded text encoded with the 'Q' encoding (described in |
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| 114 | * RFC 2047) found in a header field body. |
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| 115 | * |
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| 116 | * @param encodedText the encoded text to decode. |
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| 117 | * @param charset the Java charset to use. |
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| 118 | * @return the decoded string. |
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| 119 | * @throws UnsupportedEncodingException if the given Java charset isn't |
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| 120 | * supported. |
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| 121 | */ |
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| 122 | static String decodeQ(String encodedText, String charset, DecodeMonitor monitor) |
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| 123 | throws UnsupportedEncodingException { |
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| 124 | encodedText = replaceUnderscores(encodedText); |
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| 125 | |
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| 126 | byte[] decodedBytes = decodeQuotedPrintable(encodedText, monitor); |
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| 127 | return new String(decodedBytes, charset); |
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| 128 | } |
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| 129 | |
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| 130 | static String decodeEncodedWords(String body) { |
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| 131 | return decodeEncodedWords(body, DecodeMonitor.SILENT); |
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| 132 | } |
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| 133 | |
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| 134 | /** |
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| 135 | * Decodes a string containing encoded words as defined by RFC 2047. Encoded |
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| 136 | * words have the form =?charset?enc?encoded-text?= where enc is either 'Q' |
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| 137 | * or 'q' for quoted-printable and 'B' or 'b' for base64. |
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| 138 | * |
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| 139 | * @param body the string to decode |
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| 140 | * @param monitor the DecodeMonitor to be used. |
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| 141 | * @return the decoded string. |
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| 142 | * @throws IllegalArgumentException only if the DecodeMonitor strategy throws it (Strict parsing) |
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| 143 | */ |
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| 144 | public static String decodeEncodedWords(String body, DecodeMonitor monitor) throws IllegalArgumentException { |
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| 145 | int tailIndex = 0; |
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| 146 | boolean lastMatchValid = false; |
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| 147 | |
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| 148 | StringBuilder sb = new StringBuilder(); |
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| 149 | |
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| 150 | for (Matcher matcher = PATTERN_ENCODED_WORD.matcher(body); matcher.find();) { |
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| 151 | String separator = matcher.group(1); |
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| 152 | String mimeCharset = matcher.group(2); |
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| 153 | String encoding = matcher.group(3); |
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| 154 | String encodedText = matcher.group(4); |
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| 155 | |
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| 156 | String decoded = null; |
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| 157 | decoded = tryDecodeEncodedWord(mimeCharset, encoding, encodedText, monitor); |
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| 158 | if (decoded == null) { |
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| 159 | sb.append(matcher.group(0)); |
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| 160 | } else { |
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| 161 | if (!lastMatchValid || !CharsetUtil.isWhitespace(separator)) { |
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| 162 | sb.append(separator); |
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| 163 | } |
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| 164 | sb.append(decoded); |
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| 165 | } |
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| 166 | |
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| 167 | tailIndex = matcher.end(); |
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| 168 | lastMatchValid = decoded != null; |
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| 169 | } |
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| 170 | |
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| 171 | if (tailIndex == 0) { |
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| 172 | return body; |
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| 173 | } else { |
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| 174 | sb.append(body.substring(tailIndex)); |
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| 175 | return sb.toString(); |
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| 176 | } |
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| 177 | } |
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| 178 | |
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| 179 | // return null on error |
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| 180 | private static String tryDecodeEncodedWord(final String mimeCharset, |
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| 181 | final String encoding, final String encodedText, final DecodeMonitor monitor) { |
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| 182 | Charset charset = CharsetUtil.lookup(mimeCharset); |
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| 183 | if (charset == null) { |
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| 184 | monitor(monitor, mimeCharset, encoding, encodedText, "leaving word encoded", |
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| 185 | "Mime charser '", mimeCharset, "' doesn't have a corresponding Java charset"); |
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| 186 | return null; |
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| 187 | } |
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| 188 | |
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| 189 | if (encodedText.length() == 0) { |
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| 190 | monitor(monitor, mimeCharset, encoding, encodedText, "leaving word encoded", |
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| 191 | "Missing encoded text in encoded word"); |
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| 192 | return null; |
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| 193 | } |
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| 194 | |
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| 195 | try { |
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| 196 | if (encoding.equalsIgnoreCase("Q")) { |
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| 197 | return DecoderUtil.decodeQ(encodedText, charset.name(), monitor); |
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| 198 | } else if (encoding.equalsIgnoreCase("B")) { |
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| 199 | return DecoderUtil.decodeB(encodedText, charset.name(), monitor); |
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| 200 | } else { |
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| 201 | monitor(monitor, mimeCharset, encoding, encodedText, "leaving word encoded", |
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| 202 | "Warning: Unknown encoding in encoded word"); |
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| 203 | return null; |
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| 204 | } |
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| 205 | } catch (UnsupportedEncodingException e) { |
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| 206 | // should not happen because of isDecodingSupported check above |
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| 207 | monitor(monitor, mimeCharset, encoding, encodedText, "leaving word encoded", |
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| 208 | "Unsupported encoding (", e.getMessage(), ") in encoded word"); |
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| 209 | return null; |
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| 210 | } catch (RuntimeException e) { |
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| 211 | monitor(monitor, mimeCharset, encoding, encodedText, "leaving word encoded", |
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| 212 | "Could not decode (", e.getMessage(), ") encoded word"); |
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| 213 | return null; |
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| 214 | } |
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| 215 | } |
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| 216 | |
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| 217 | private static void monitor(DecodeMonitor monitor, String mimeCharset, String encoding, |
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| 218 | String encodedText, String dropDesc, String... strings) throws IllegalArgumentException { |
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| 219 | if (monitor.isListening()) { |
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| 220 | String encodedWord = recombine(mimeCharset, encoding, encodedText); |
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| 221 | StringBuilder text = new StringBuilder(); |
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| 222 | for (String str : strings) { |
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| 223 | text.append(str); |
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| 224 | } |
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| 225 | text.append(" ("); |
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| 226 | text.append(encodedWord); |
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| 227 | text.append(")"); |
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| 228 | String exceptionDesc = text.toString(); |
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| 229 | if (monitor.warn(exceptionDesc, dropDesc)) |
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| 230 | throw new IllegalArgumentException(text.toString()); |
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| 231 | } |
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| 232 | } |
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| 233 | |
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| 234 | private static String recombine(final String mimeCharset, |
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| 235 | final String encoding, final String encodedText) { |
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| 236 | return "=?" + mimeCharset + "?" + encoding + "?" + encodedText + "?="; |
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| 237 | } |
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| 238 | |
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| 239 | // Replace _ with =20 |
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| 240 | private static String replaceUnderscores(String str) { |
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| 241 | // probably faster than String#replace(CharSequence, CharSequence) |
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| 242 | |
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| 243 | StringBuilder sb = new StringBuilder(128); |
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| 244 | |
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| 245 | for (int i = 0; i < str.length(); i++) { |
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| 246 | char c = str.charAt(i); |
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| 247 | if (c == '_') { |
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| 248 | sb.append("=20"); |
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| 249 | } else { |
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| 250 | sb.append(c); |
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| 251 | } |
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| 252 | } |
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| 253 | |
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| 254 | return sb.toString(); |
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| 255 | } |
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| 256 | } |
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