[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.nio.ByteBuffer; |
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| 23 | import java.nio.charset.Charset; |
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| 24 | import java.util.BitSet; |
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| 25 | import java.util.Locale; |
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| 26 | |
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| 27 | import org.apache.james.mime4j.util.CharsetUtil; |
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| 28 | |
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| 29 | /** |
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| 30 | * Static methods for encoding header field values. This includes encoded-words |
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| 31 | * as defined in <a href='http://www.faqs.org/rfcs/rfc2047.html'>RFC 2047</a> |
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| 32 | * or display-names of an e-mail address, for example. |
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| 33 | */ |
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| 34 | public class EncoderUtil { |
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| 35 | private static final byte[] BASE64_TABLE = Base64OutputStream.BASE64_TABLE; |
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| 36 | private static final char BASE64_PAD = '='; |
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| 37 | |
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| 38 | private static final BitSet Q_REGULAR_CHARS = initChars("=_?"); |
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| 39 | |
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| 40 | private static final BitSet Q_RESTRICTED_CHARS = initChars("=_?\"#$%&'(),.:;<>@[\\]^`{|}~"); |
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| 41 | |
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| 42 | private static final int MAX_USED_CHARACTERS = 50; |
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| 43 | |
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| 44 | private static final String ENC_WORD_PREFIX = "=?"; |
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| 45 | private static final String ENC_WORD_SUFFIX = "?="; |
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| 46 | |
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| 47 | private static final int ENCODED_WORD_MAX_LENGTH = 75; // RFC 2047 |
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| 48 | |
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| 49 | private static final BitSet TOKEN_CHARS = initChars("()<>@,;:\\\"/[]?="); |
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| 50 | |
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| 51 | private static final BitSet ATEXT_CHARS = initChars("()<>@.,;:\\\"[]"); |
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| 52 | |
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| 53 | private static BitSet initChars(String specials) { |
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| 54 | BitSet bs = new BitSet(128); |
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| 55 | for (char ch = 33; ch < 127; ch++) { |
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| 56 | if (specials.indexOf(ch) == -1) { |
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| 57 | bs.set(ch); |
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| 58 | } |
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| 59 | } |
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| 60 | return bs; |
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| 61 | } |
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| 62 | |
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| 63 | /** |
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| 64 | * Selects one of the two encodings specified in RFC 2047. |
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| 65 | */ |
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| 66 | public enum Encoding { |
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| 67 | /** The B encoding (identical to base64 defined in RFC 2045). */ |
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| 68 | B, |
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| 69 | /** The Q encoding (similar to quoted-printable defined in RFC 2045). */ |
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| 70 | Q |
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| 71 | } |
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| 72 | |
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| 73 | /** |
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| 74 | * Indicates the intended usage of an encoded word. |
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| 75 | */ |
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| 76 | public enum Usage { |
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| 77 | /** |
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| 78 | * Encoded word is used to replace a 'text' token in any Subject or |
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| 79 | * Comments header field. |
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| 80 | */ |
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| 81 | TEXT_TOKEN, |
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| 82 | /** |
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| 83 | * Encoded word is used to replace a 'word' entity within a 'phrase', |
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| 84 | * for example, one that precedes an address in a From, To, or Cc |
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| 85 | * header. |
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| 86 | */ |
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| 87 | WORD_ENTITY |
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| 88 | } |
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| 89 | |
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| 90 | private EncoderUtil() { |
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| 91 | } |
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| 92 | |
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| 93 | /** |
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| 94 | * Encodes the display-name portion of an address. See <a |
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| 95 | * href='http://www.faqs.org/rfcs/rfc5322.html'>RFC 5322</a> section 3.4 |
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| 96 | * and <a href='http://www.faqs.org/rfcs/rfc2047.html'>RFC 2047</a> section |
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| 97 | * 5.3. The specified string should not be folded. |
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| 98 | * |
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| 99 | * @param displayName |
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| 100 | * display-name to encode. |
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| 101 | * @return encoded display-name. |
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| 102 | */ |
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| 103 | public static String encodeAddressDisplayName(String displayName) { |
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| 104 | // display-name = phrase |
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| 105 | // phrase = 1*( encoded-word / word ) |
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| 106 | // word = atom / quoted-string |
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| 107 | // atom = [CFWS] 1*atext [CFWS] |
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| 108 | // CFWS = comment or folding white space |
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| 109 | |
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| 110 | if (isAtomPhrase(displayName)) { |
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| 111 | return displayName; |
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| 112 | } else if (hasToBeEncoded(displayName, 0)) { |
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| 113 | return encodeEncodedWord(displayName, Usage.WORD_ENTITY); |
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| 114 | } else { |
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| 115 | return quote(displayName); |
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| 116 | } |
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| 117 | } |
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| 118 | |
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| 119 | /** |
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| 120 | * Encodes the local part of an address specification as described in RFC |
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| 121 | * 5322 section 3.4.1. Leading and trailing CFWS should have been removed |
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| 122 | * before calling this method. The specified string should not contain any |
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| 123 | * illegal (control or non-ASCII) characters. |
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| 124 | * |
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| 125 | * @param localPart |
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| 126 | * the local part to encode |
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| 127 | * @return the encoded local part. |
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| 128 | */ |
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| 129 | public static String encodeAddressLocalPart(String localPart) { |
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| 130 | // local-part = dot-atom / quoted-string |
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| 131 | // dot-atom = [CFWS] dot-atom-text [CFWS] |
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| 132 | // CFWS = comment or folding white space |
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| 133 | |
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| 134 | if (isDotAtomText(localPart)) { |
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| 135 | return localPart; |
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| 136 | } else { |
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| 137 | return quote(localPart); |
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| 138 | } |
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| 139 | } |
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| 140 | |
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| 141 | /** |
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| 142 | * Encodes the specified strings into a header parameter as described in RFC |
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| 143 | * 2045 section 5.1 and RFC 2183 section 2. The specified strings should not |
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| 144 | * contain any illegal (control or non-ASCII) characters. |
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| 145 | * |
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| 146 | * @param name |
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| 147 | * parameter name. |
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| 148 | * @param value |
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| 149 | * parameter value. |
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| 150 | * @return encoded result. |
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| 151 | */ |
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| 152 | public static String encodeHeaderParameter(String name, String value) { |
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| 153 | name = name.toLowerCase(Locale.US); |
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| 154 | |
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| 155 | // value := token / quoted-string |
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| 156 | if (isToken(value)) { |
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| 157 | return name + "=" + value; |
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| 158 | } else { |
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| 159 | return name + "=" + quote(value); |
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| 160 | } |
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| 161 | } |
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| 162 | |
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| 163 | /** |
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| 164 | * Shortcut method that encodes the specified text into an encoded-word if |
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| 165 | * the text has to be encoded. |
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| 166 | * |
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| 167 | * @param text |
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| 168 | * text to encode. |
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| 169 | * @param usage |
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| 170 | * whether the encoded-word is to be used to replace a text token |
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| 171 | * or a word entity (see RFC 822). |
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| 172 | * @param usedCharacters |
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| 173 | * number of characters already used up (<code>0 <= usedCharacters <= 50</code>). |
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| 174 | * @return the specified text if encoding is not necessary or an encoded |
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| 175 | * word or a sequence of encoded words otherwise. |
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| 176 | */ |
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| 177 | public static String encodeIfNecessary(String text, Usage usage, |
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| 178 | int usedCharacters) { |
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| 179 | if (hasToBeEncoded(text, usedCharacters)) |
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| 180 | return encodeEncodedWord(text, usage, usedCharacters); |
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| 181 | else |
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| 182 | return text; |
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| 183 | } |
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| 184 | |
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| 185 | /** |
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| 186 | * Determines if the specified string has to encoded into an encoded-word. |
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| 187 | * Returns <code>true</code> if the text contains characters that don't |
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| 188 | * fall into the printable ASCII character set or if the text contains a |
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| 189 | * 'word' (sequence of non-whitespace characters) longer than 77 characters |
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| 190 | * (including characters already used up in the line). |
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| 191 | * |
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| 192 | * @param text |
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| 193 | * text to analyze. |
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| 194 | * @param usedCharacters |
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| 195 | * number of characters already used up (<code>0 <= usedCharacters <= 50</code>). |
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| 196 | * @return <code>true</code> if the specified text has to be encoded into |
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| 197 | * an encoded-word, <code>false</code> otherwise. |
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| 198 | */ |
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| 199 | public static boolean hasToBeEncoded(String text, int usedCharacters) { |
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| 200 | if (text == null) |
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| 201 | throw new IllegalArgumentException(); |
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| 202 | if (usedCharacters < 0 || usedCharacters > MAX_USED_CHARACTERS) |
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| 203 | throw new IllegalArgumentException(); |
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| 204 | |
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| 205 | int nonWhiteSpaceCount = usedCharacters; |
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| 206 | |
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| 207 | for (int idx = 0; idx < text.length(); idx++) { |
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| 208 | char ch = text.charAt(idx); |
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| 209 | if (ch == '\t' || ch == ' ') { |
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| 210 | nonWhiteSpaceCount = 0; |
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| 211 | } else { |
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| 212 | nonWhiteSpaceCount++; |
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| 213 | if (nonWhiteSpaceCount > 77) { |
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| 214 | // Line cannot be folded into multiple lines with no more |
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| 215 | // than 78 characters each. Encoding as encoded-words makes |
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| 216 | // that possible. One character has to be reserved for |
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| 217 | // folding white space; that leaves 77 characters. |
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| 218 | return true; |
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| 219 | } |
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| 220 | |
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| 221 | if (ch < 32 || ch >= 127) { |
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| 222 | // non-printable ascii character has to be encoded |
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| 223 | return true; |
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| 224 | } |
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| 225 | } |
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| 226 | } |
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| 227 | |
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| 228 | return false; |
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| 229 | } |
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| 230 | |
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| 231 | /** |
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| 232 | * Encodes the specified text into an encoded word or a sequence of encoded |
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| 233 | * words separated by space. The text is separated into a sequence of |
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| 234 | * encoded words if it does not fit in a single one. |
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| 235 | * <p> |
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| 236 | * The charset to encode the specified text into a byte array and the |
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| 237 | * encoding to use for the encoded-word are detected automatically. |
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| 238 | * <p> |
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| 239 | * This method assumes that zero characters have already been used up in the |
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| 240 | * current line. |
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| 241 | * |
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| 242 | * @param text |
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| 243 | * text to encode. |
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| 244 | * @param usage |
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| 245 | * whether the encoded-word is to be used to replace a text token |
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| 246 | * or a word entity (see RFC 822). |
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| 247 | * @return the encoded word (or sequence of encoded words if the given text |
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| 248 | * does not fit in a single encoded word). |
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| 249 | * @see #hasToBeEncoded(String, int) |
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| 250 | */ |
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| 251 | public static String encodeEncodedWord(String text, Usage usage) { |
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| 252 | return encodeEncodedWord(text, usage, 0, null, null); |
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| 253 | } |
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| 254 | |
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| 255 | /** |
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| 256 | * Encodes the specified text into an encoded word or a sequence of encoded |
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| 257 | * words separated by space. The text is separated into a sequence of |
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| 258 | * encoded words if it does not fit in a single one. |
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| 259 | * <p> |
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| 260 | * The charset to encode the specified text into a byte array and the |
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| 261 | * encoding to use for the encoded-word are detected automatically. |
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| 262 | * |
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| 263 | * @param text |
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| 264 | * text to encode. |
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| 265 | * @param usage |
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| 266 | * whether the encoded-word is to be used to replace a text token |
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| 267 | * or a word entity (see RFC 822). |
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| 268 | * @param usedCharacters |
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| 269 | * number of characters already used up (<code>0 <= usedCharacters <= 50</code>). |
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| 270 | * @return the encoded word (or sequence of encoded words if the given text |
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| 271 | * does not fit in a single encoded word). |
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| 272 | * @see #hasToBeEncoded(String, int) |
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| 273 | */ |
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| 274 | public static String encodeEncodedWord(String text, Usage usage, |
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| 275 | int usedCharacters) { |
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| 276 | return encodeEncodedWord(text, usage, usedCharacters, null, null); |
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| 277 | } |
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| 278 | |
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| 279 | /** |
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| 280 | * Encodes the specified text into an encoded word or a sequence of encoded |
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| 281 | * words separated by space. The text is separated into a sequence of |
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| 282 | * encoded words if it does not fit in a single one. |
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| 283 | * |
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| 284 | * @param text |
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| 285 | * text to encode. |
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| 286 | * @param usage |
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| 287 | * whether the encoded-word is to be used to replace a text token |
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| 288 | * or a word entity (see RFC 822). |
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| 289 | * @param usedCharacters |
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| 290 | * number of characters already used up (<code>0 <= usedCharacters <= 50</code>). |
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| 291 | * @param charset |
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| 292 | * the Java charset that should be used to encode the specified |
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| 293 | * string into a byte array. A suitable charset is detected |
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| 294 | * automatically if this parameter is <code>null</code>. |
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| 295 | * @param encoding |
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| 296 | * the encoding to use for the encoded-word (either B or Q). A |
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| 297 | * suitable encoding is automatically chosen if this parameter is |
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| 298 | * <code>null</code>. |
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| 299 | * @return the encoded word (or sequence of encoded words if the given text |
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| 300 | * does not fit in a single encoded word). |
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| 301 | * @see #hasToBeEncoded(String, int) |
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| 302 | */ |
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| 303 | public static String encodeEncodedWord(String text, Usage usage, |
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| 304 | int usedCharacters, Charset charset, Encoding encoding) { |
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| 305 | if (text == null) |
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| 306 | throw new IllegalArgumentException(); |
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| 307 | if (usedCharacters < 0 || usedCharacters > MAX_USED_CHARACTERS) |
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| 308 | throw new IllegalArgumentException(); |
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| 309 | |
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| 310 | if (charset == null) |
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| 311 | charset = determineCharset(text); |
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| 312 | |
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| 313 | String mimeCharset = CharsetUtil.toMimeCharset(charset.name()); |
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| 314 | if (mimeCharset == null) { |
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| 315 | // cannot happen if charset was originally null |
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| 316 | throw new IllegalArgumentException("Unsupported charset"); |
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| 317 | } |
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| 318 | |
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| 319 | byte[] bytes = encode(text, charset); |
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| 320 | |
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| 321 | if (encoding == null) |
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| 322 | encoding = determineEncoding(bytes, usage); |
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| 323 | |
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| 324 | if (encoding == Encoding.B) { |
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| 325 | String prefix = ENC_WORD_PREFIX + mimeCharset + "?B?"; |
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| 326 | return encodeB(prefix, text, usedCharacters, charset, bytes); |
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| 327 | } else { |
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| 328 | String prefix = ENC_WORD_PREFIX + mimeCharset + "?Q?"; |
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| 329 | return encodeQ(prefix, text, usage, usedCharacters, charset, bytes); |
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| 330 | } |
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| 331 | } |
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| 332 | |
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| 333 | /** |
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| 334 | * Encodes the specified byte array using the B encoding defined in RFC |
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| 335 | * 2047. |
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| 336 | * |
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| 337 | * @param bytes |
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| 338 | * byte array to encode. |
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| 339 | * @return encoded string. |
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| 340 | */ |
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| 341 | public static String encodeB(byte[] bytes) { |
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| 342 | StringBuilder sb = new StringBuilder(); |
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| 343 | |
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| 344 | int idx = 0; |
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| 345 | final int end = bytes.length; |
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| 346 | for (; idx < end - 2; idx += 3) { |
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| 347 | int data = (bytes[idx] & 0xff) << 16 | (bytes[idx + 1] & 0xff) << 8 |
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| 348 | | bytes[idx + 2] & 0xff; |
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| 349 | sb.append((char) BASE64_TABLE[data >> 18 & 0x3f]); |
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| 350 | sb.append((char) BASE64_TABLE[data >> 12 & 0x3f]); |
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| 351 | sb.append((char) BASE64_TABLE[data >> 6 & 0x3f]); |
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| 352 | sb.append((char) BASE64_TABLE[data & 0x3f]); |
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| 353 | } |
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| 354 | |
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| 355 | if (idx == end - 2) { |
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| 356 | int data = (bytes[idx] & 0xff) << 16 | (bytes[idx + 1] & 0xff) << 8; |
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| 357 | sb.append((char) BASE64_TABLE[data >> 18 & 0x3f]); |
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| 358 | sb.append((char) BASE64_TABLE[data >> 12 & 0x3f]); |
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| 359 | sb.append((char) BASE64_TABLE[data >> 6 & 0x3f]); |
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| 360 | sb.append(BASE64_PAD); |
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| 361 | |
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| 362 | } else if (idx == end - 1) { |
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| 363 | int data = (bytes[idx] & 0xff) << 16; |
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| 364 | sb.append((char) BASE64_TABLE[data >> 18 & 0x3f]); |
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| 365 | sb.append((char) BASE64_TABLE[data >> 12 & 0x3f]); |
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| 366 | sb.append(BASE64_PAD); |
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| 367 | sb.append(BASE64_PAD); |
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| 368 | } |
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| 369 | |
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| 370 | return sb.toString(); |
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| 371 | } |
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| 372 | |
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| 373 | /** |
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| 374 | * Encodes the specified byte array using the Q encoding defined in RFC |
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| 375 | * 2047. |
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| 376 | * |
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| 377 | * @param bytes |
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| 378 | * byte array to encode. |
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| 379 | * @param usage |
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| 380 | * whether the encoded-word is to be used to replace a text token |
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| 381 | * or a word entity (see RFC 822). |
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| 382 | * @return encoded string. |
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| 383 | */ |
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| 384 | public static String encodeQ(byte[] bytes, Usage usage) { |
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| 385 | BitSet qChars = usage == Usage.TEXT_TOKEN ? Q_REGULAR_CHARS |
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| 386 | : Q_RESTRICTED_CHARS; |
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| 387 | |
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| 388 | StringBuilder sb = new StringBuilder(); |
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| 389 | |
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| 390 | final int end = bytes.length; |
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| 391 | for (int idx = 0; idx < end; idx++) { |
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| 392 | int v = bytes[idx] & 0xff; |
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| 393 | if (v == 32) { |
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| 394 | sb.append('_'); |
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| 395 | } else if (!qChars.get(v)) { |
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| 396 | sb.append('='); |
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| 397 | sb.append(hexDigit(v >>> 4)); |
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| 398 | sb.append(hexDigit(v & 0xf)); |
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| 399 | } else { |
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| 400 | sb.append((char) v); |
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| 401 | } |
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| 402 | } |
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| 403 | |
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| 404 | return sb.toString(); |
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| 405 | } |
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| 406 | |
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| 407 | /** |
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| 408 | * Tests whether the specified string is a token as defined in RFC 2045 |
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| 409 | * section 5.1. |
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| 410 | * |
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| 411 | * @param str |
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| 412 | * string to test. |
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| 413 | * @return <code>true</code> if the specified string is a RFC 2045 token, |
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| 414 | * <code>false</code> otherwise. |
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| 415 | */ |
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| 416 | public static boolean isToken(String str) { |
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| 417 | // token := 1*<any (US-ASCII) CHAR except SPACE, CTLs, or tspecials> |
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| 418 | // tspecials := "(" / ")" / "<" / ">" / "@" / "," / ";" / ":" / "\" / |
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| 419 | // <"> / "/" / "[" / "]" / "?" / "=" |
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| 420 | // CTL := 0.- 31., 127. |
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| 421 | |
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| 422 | final int length = str.length(); |
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| 423 | if (length == 0) |
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| 424 | return false; |
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| 425 | |
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| 426 | for (int idx = 0; idx < length; idx++) { |
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| 427 | char ch = str.charAt(idx); |
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| 428 | if (!TOKEN_CHARS.get(ch)) |
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| 429 | return false; |
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| 430 | } |
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| 431 | |
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| 432 | return true; |
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| 433 | } |
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| 434 | |
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| 435 | private static boolean isAtomPhrase(String str) { |
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| 436 | // atom = [CFWS] 1*atext [CFWS] |
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| 437 | |
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| 438 | boolean containsAText = false; |
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| 439 | |
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| 440 | final int length = str.length(); |
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| 441 | for (int idx = 0; idx < length; idx++) { |
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| 442 | char ch = str.charAt(idx); |
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| 443 | if (ATEXT_CHARS.get(ch)) { |
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| 444 | containsAText = true; |
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| 445 | } else if (!CharsetUtil.isWhitespace(ch)) { |
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| 446 | return false; |
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| 447 | } |
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| 448 | } |
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| 449 | |
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| 450 | return containsAText; |
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| 451 | } |
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| 452 | |
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| 453 | // RFC 5322 section 3.2.3 |
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| 454 | private static boolean isDotAtomText(String str) { |
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| 455 | // dot-atom-text = 1*atext *("." 1*atext) |
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| 456 | // atext = ALPHA / DIGIT / "!" / "#" / "$" / "%" / "&" / "'" / "*" / |
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| 457 | // "+" / "-" / "/" / "=" / "?" / "^" / "_" / "`" / "{" / "|" / "}" / "~" |
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| 458 | |
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| 459 | char prev = '.'; |
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| 460 | |
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| 461 | final int length = str.length(); |
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| 462 | if (length == 0) |
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| 463 | return false; |
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| 464 | |
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| 465 | for (int idx = 0; idx < length; idx++) { |
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| 466 | char ch = str.charAt(idx); |
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| 467 | |
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| 468 | if (ch == '.') { |
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| 469 | if (prev == '.' || idx == length - 1) |
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| 470 | return false; |
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| 471 | } else { |
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| 472 | if (!ATEXT_CHARS.get(ch)) |
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| 473 | return false; |
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| 474 | } |
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| 475 | |
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| 476 | prev = ch; |
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| 477 | } |
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| 478 | |
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| 479 | return true; |
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| 480 | } |
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| 481 | |
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| 482 | // RFC 5322 section 3.2.4 |
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| 483 | private static String quote(String str) { |
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| 484 | // quoted-string = [CFWS] DQUOTE *([FWS] qcontent) [FWS] DQUOTE [CFWS] |
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| 485 | // qcontent = qtext / quoted-pair |
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| 486 | // qtext = %d33 / %d35-91 / %d93-126 |
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| 487 | // quoted-pair = ("\" (VCHAR / WSP)) |
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| 488 | // VCHAR = %x21-7E |
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| 489 | // DQUOTE = %x22 |
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| 490 | |
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| 491 | String escaped = str.replaceAll("[\\\\\"]", "\\\\$0"); |
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| 492 | return "\"" + escaped + "\""; |
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| 493 | } |
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| 494 | |
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| 495 | private static String encodeB(String prefix, String text, |
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| 496 | int usedCharacters, Charset charset, byte[] bytes) { |
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| 497 | int encodedLength = bEncodedLength(bytes); |
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| 498 | |
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| 499 | int totalLength = prefix.length() + encodedLength |
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| 500 | + ENC_WORD_SUFFIX.length(); |
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| 501 | if (totalLength <= ENCODED_WORD_MAX_LENGTH - usedCharacters) { |
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| 502 | return prefix + encodeB(bytes) + ENC_WORD_SUFFIX; |
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| 503 | } else { |
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| 504 | String part1 = text.substring(0, text.length() / 2); |
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| 505 | byte[] bytes1 = encode(part1, charset); |
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| 506 | String word1 = encodeB(prefix, part1, usedCharacters, charset, |
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| 507 | bytes1); |
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| 508 | |
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| 509 | String part2 = text.substring(text.length() / 2); |
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| 510 | byte[] bytes2 = encode(part2, charset); |
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| 511 | String word2 = encodeB(prefix, part2, 0, charset, bytes2); |
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| 512 | |
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| 513 | return word1 + " " + word2; |
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| 514 | } |
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| 515 | } |
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| 516 | |
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| 517 | private static int bEncodedLength(byte[] bytes) { |
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| 518 | return (bytes.length + 2) / 3 * 4; |
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| 519 | } |
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| 520 | |
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| 521 | private static String encodeQ(String prefix, String text, Usage usage, |
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| 522 | int usedCharacters, Charset charset, byte[] bytes) { |
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| 523 | int encodedLength = qEncodedLength(bytes, usage); |
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| 524 | |
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| 525 | int totalLength = prefix.length() + encodedLength |
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| 526 | + ENC_WORD_SUFFIX.length(); |
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| 527 | if (totalLength <= ENCODED_WORD_MAX_LENGTH - usedCharacters) { |
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| 528 | return prefix + encodeQ(bytes, usage) + ENC_WORD_SUFFIX; |
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| 529 | } else { |
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| 530 | String part1 = text.substring(0, text.length() / 2); |
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| 531 | byte[] bytes1 = encode(part1, charset); |
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| 532 | String word1 = encodeQ(prefix, part1, usage, usedCharacters, |
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| 533 | charset, bytes1); |
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| 534 | |
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| 535 | String part2 = text.substring(text.length() / 2); |
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| 536 | byte[] bytes2 = encode(part2, charset); |
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| 537 | String word2 = encodeQ(prefix, part2, usage, 0, charset, bytes2); |
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| 538 | |
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| 539 | return word1 + " " + word2; |
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| 540 | } |
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| 541 | } |
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| 542 | |
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| 543 | private static int qEncodedLength(byte[] bytes, Usage usage) { |
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| 544 | BitSet qChars = usage == Usage.TEXT_TOKEN ? Q_REGULAR_CHARS |
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| 545 | : Q_RESTRICTED_CHARS; |
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| 546 | |
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| 547 | int count = 0; |
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| 548 | |
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| 549 | for (int idx = 0; idx < bytes.length; idx++) { |
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| 550 | int v = bytes[idx] & 0xff; |
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| 551 | if (v == 32) { |
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| 552 | count++; |
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| 553 | } else if (!qChars.get(v)) { |
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| 554 | count += 3; |
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| 555 | } else { |
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| 556 | count++; |
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| 557 | } |
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| 558 | } |
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| 559 | |
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| 560 | return count; |
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| 561 | } |
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| 562 | |
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| 563 | private static byte[] encode(String text, Charset charset) { |
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| 564 | ByteBuffer buffer = charset.encode(text); |
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| 565 | byte[] bytes = new byte[buffer.limit()]; |
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| 566 | buffer.get(bytes); |
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| 567 | return bytes; |
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| 568 | } |
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| 569 | |
---|
| 570 | private static Charset determineCharset(String text) { |
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| 571 | // it is an important property of iso-8859-1 that it directly maps |
---|
| 572 | // unicode code points 0000 to 00ff to byte values 00 to ff. |
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| 573 | boolean ascii = true; |
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| 574 | final int len = text.length(); |
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| 575 | for (int index = 0; index < len; index++) { |
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| 576 | char ch = text.charAt(index); |
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| 577 | if (ch > 0xff) { |
---|
| 578 | return CharsetUtil.UTF_8; |
---|
| 579 | } |
---|
| 580 | if (ch > 0x7f) { |
---|
| 581 | ascii = false; |
---|
| 582 | } |
---|
| 583 | } |
---|
| 584 | return ascii ? CharsetUtil.US_ASCII : CharsetUtil.ISO_8859_1; |
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| 585 | } |
---|
| 586 | |
---|
| 587 | private static Encoding determineEncoding(byte[] bytes, Usage usage) { |
---|
| 588 | if (bytes.length == 0) |
---|
| 589 | return Encoding.Q; |
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| 590 | |
---|
| 591 | BitSet qChars = usage == Usage.TEXT_TOKEN ? Q_REGULAR_CHARS |
---|
| 592 | : Q_RESTRICTED_CHARS; |
---|
| 593 | |
---|
| 594 | int qEncoded = 0; |
---|
| 595 | for (int i = 0; i < bytes.length; i++) { |
---|
| 596 | int v = bytes[i] & 0xff; |
---|
| 597 | if (v != 32 && !qChars.get(v)) { |
---|
| 598 | qEncoded++; |
---|
| 599 | } |
---|
| 600 | } |
---|
| 601 | |
---|
| 602 | int percentage = qEncoded * 100 / bytes.length; |
---|
| 603 | return percentage > 30 ? Encoding.B : Encoding.Q; |
---|
| 604 | } |
---|
| 605 | |
---|
| 606 | private static char hexDigit(int i) { |
---|
| 607 | return i < 10 ? (char) (i + '0') : (char) (i - 10 + 'A'); |
---|
| 608 | } |
---|
| 609 | } |
---|