Eric Erfanian | ccca315 | 2017-02-22 16:32:36 -0800 | [diff] [blame] | 1 | /**************************************************************** |
| 2 | * Licensed to the Apache Software Foundation (ASF) under one * |
| 3 | * or more contributor license agreements. See the NOTICE file * |
| 4 | * distributed with this work for additional information * |
| 5 | * regarding copyright ownership. The ASF licenses this file * |
| 6 | * to you under the Apache License, Version 2.0 (the * |
| 7 | * "License"); you may not use this file except in compliance * |
| 8 | * with the License. You may obtain a copy of the License at * |
| 9 | * * |
| 10 | * http://www.apache.org/licenses/LICENSE-2.0 * |
| 11 | * * |
| 12 | * Unless required by applicable law or agreed to in writing, * |
| 13 | * software distributed under the License is distributed on an * |
| 14 | * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY * |
| 15 | * KIND, either express or implied. See the License for the * |
| 16 | * specific language governing permissions and limitations * |
| 17 | * under the License. * |
| 18 | ****************************************************************/ |
| 19 | |
| 20 | package org.apache.james.mime4j.codec; |
| 21 | |
| 22 | import java.nio.ByteBuffer; |
| 23 | import java.nio.charset.Charset; |
| 24 | import java.util.BitSet; |
| 25 | import java.util.Locale; |
| 26 | |
| 27 | import org.apache.james.mime4j.util.CharsetUtil; |
| 28 | |
| 29 | /** |
| 30 | * ANDROID: THIS CLASS IS COPIED FROM A NEWER VERSION OF MIME4J |
| 31 | */ |
| 32 | |
| 33 | /** |
| 34 | * Static methods for encoding header field values. This includes encoded-words |
| 35 | * as defined in <a href='http://www.faqs.org/rfcs/rfc2047.html'>RFC 2047</a> |
| 36 | * or display-names of an e-mail address, for example. |
| 37 | * |
| 38 | */ |
| 39 | public class EncoderUtil { |
| 40 | |
| 41 | // This array is a lookup table that translates 6-bit positive integer index |
| 42 | // values into their "Base64 Alphabet" equivalents as specified in Table 1 |
| 43 | // of RFC 2045. |
| 44 | // ANDROID: THIS TABLE IS COPIED FROM BASE64OUTPUTSTREAM |
| 45 | static final byte[] BASE64_TABLE = { 'A', 'B', 'C', 'D', 'E', 'F', |
| 46 | 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', |
| 47 | 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', |
| 48 | 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', |
| 49 | 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', |
| 50 | '6', '7', '8', '9', '+', '/' }; |
| 51 | |
| 52 | // Byte used to pad output. |
| 53 | private static final byte BASE64_PAD = '='; |
| 54 | |
| 55 | private static final BitSet Q_REGULAR_CHARS = initChars("=_?"); |
| 56 | |
| 57 | private static final BitSet Q_RESTRICTED_CHARS = initChars("=_?\"#$%&'(),.:;<>@[\\]^`{|}~"); |
| 58 | |
| 59 | private static final int MAX_USED_CHARACTERS = 50; |
| 60 | |
| 61 | private static final String ENC_WORD_PREFIX = "=?"; |
| 62 | private static final String ENC_WORD_SUFFIX = "?="; |
| 63 | |
| 64 | private static final int ENCODED_WORD_MAX_LENGTH = 75; // RFC 2047 |
| 65 | |
| 66 | private static final BitSet TOKEN_CHARS = initChars("()<>@,;:\\\"/[]?="); |
| 67 | |
| 68 | private static final BitSet ATEXT_CHARS = initChars("()<>@.,;:\\\"[]"); |
| 69 | |
| 70 | private static BitSet initChars(String specials) { |
| 71 | BitSet bs = new BitSet(128); |
| 72 | for (char ch = 33; ch < 127; ch++) { |
| 73 | if (specials.indexOf(ch) == -1) { |
| 74 | bs.set(ch); |
| 75 | } |
| 76 | } |
| 77 | return bs; |
| 78 | } |
| 79 | |
| 80 | /** |
| 81 | * Selects one of the two encodings specified in RFC 2047. |
| 82 | */ |
| 83 | public enum Encoding { |
| 84 | /** The B encoding (identical to base64 defined in RFC 2045). */ |
| 85 | B, |
| 86 | /** The Q encoding (similar to quoted-printable defined in RFC 2045). */ |
| 87 | Q |
| 88 | } |
| 89 | |
| 90 | /** |
| 91 | * Indicates the intended usage of an encoded word. |
| 92 | */ |
| 93 | public enum Usage { |
| 94 | /** |
| 95 | * Encoded word is used to replace a 'text' token in any Subject or |
| 96 | * Comments header field. |
| 97 | */ |
| 98 | TEXT_TOKEN, |
| 99 | /** |
| 100 | * Encoded word is used to replace a 'word' entity within a 'phrase', |
| 101 | * for example, one that precedes an address in a From, To, or Cc |
| 102 | * header. |
| 103 | */ |
| 104 | WORD_ENTITY |
| 105 | } |
| 106 | |
| 107 | private EncoderUtil() { |
| 108 | } |
| 109 | |
| 110 | /** |
| 111 | * Encodes the display-name portion of an address. See <a |
| 112 | * href='http://www.faqs.org/rfcs/rfc5322.html'>RFC 5322</a> section 3.4 |
| 113 | * and <a href='http://www.faqs.org/rfcs/rfc2047.html'>RFC 2047</a> section |
| 114 | * 5.3. The specified string should not be folded. |
| 115 | * |
| 116 | * @param displayName |
| 117 | * display-name to encode. |
| 118 | * @return encoded display-name. |
| 119 | */ |
| 120 | public static String encodeAddressDisplayName(String displayName) { |
| 121 | // display-name = phrase |
| 122 | // phrase = 1*( encoded-word / word ) |
| 123 | // word = atom / quoted-string |
| 124 | // atom = [CFWS] 1*atext [CFWS] |
| 125 | // CFWS = comment or folding white space |
| 126 | |
| 127 | if (isAtomPhrase(displayName)) { |
| 128 | return displayName; |
| 129 | } else if (hasToBeEncoded(displayName, 0)) { |
| 130 | return encodeEncodedWord(displayName, Usage.WORD_ENTITY); |
| 131 | } else { |
| 132 | return quote(displayName); |
| 133 | } |
| 134 | } |
| 135 | |
| 136 | /** |
| 137 | * Encodes the local part of an address specification as described in RFC |
| 138 | * 5322 section 3.4.1. Leading and trailing CFWS should have been removed |
| 139 | * before calling this method. The specified string should not contain any |
| 140 | * illegal (control or non-ASCII) characters. |
| 141 | * |
| 142 | * @param localPart |
| 143 | * the local part to encode |
| 144 | * @return the encoded local part. |
| 145 | */ |
| 146 | public static String encodeAddressLocalPart(String localPart) { |
| 147 | // local-part = dot-atom / quoted-string |
| 148 | // dot-atom = [CFWS] dot-atom-text [CFWS] |
| 149 | // CFWS = comment or folding white space |
| 150 | |
| 151 | if (isDotAtomText(localPart)) { |
| 152 | return localPart; |
| 153 | } else { |
| 154 | return quote(localPart); |
| 155 | } |
| 156 | } |
| 157 | |
| 158 | /** |
| 159 | * Encodes the specified strings into a header parameter as described in RFC |
| 160 | * 2045 section 5.1 and RFC 2183 section 2. The specified strings should not |
| 161 | * contain any illegal (control or non-ASCII) characters. |
| 162 | * |
| 163 | * @param name |
| 164 | * parameter name. |
| 165 | * @param value |
| 166 | * parameter value. |
| 167 | * @return encoded result. |
| 168 | */ |
| 169 | public static String encodeHeaderParameter(String name, String value) { |
| 170 | name = name.toLowerCase(Locale.US); |
| 171 | |
| 172 | // value := token / quoted-string |
| 173 | if (isToken(value)) { |
| 174 | return name + "=" + value; |
| 175 | } else { |
| 176 | return name + "=" + quote(value); |
| 177 | } |
| 178 | } |
| 179 | |
| 180 | /** |
| 181 | * Shortcut method that encodes the specified text into an encoded-word if |
| 182 | * the text has to be encoded. |
| 183 | * |
| 184 | * @param text |
| 185 | * text to encode. |
| 186 | * @param usage |
| 187 | * whether the encoded-word is to be used to replace a text token |
| 188 | * or a word entity (see RFC 822). |
| 189 | * @param usedCharacters |
| 190 | * number of characters already used up (<code>0 <= usedCharacters <= 50</code>). |
| 191 | * @return the specified text if encoding is not necessary or an encoded |
| 192 | * word or a sequence of encoded words otherwise. |
| 193 | */ |
| 194 | public static String encodeIfNecessary(String text, Usage usage, |
| 195 | int usedCharacters) { |
| 196 | if (hasToBeEncoded(text, usedCharacters)) |
| 197 | return encodeEncodedWord(text, usage, usedCharacters); |
| 198 | else |
| 199 | return text; |
| 200 | } |
| 201 | |
| 202 | /** |
| 203 | * Determines if the specified string has to encoded into an encoded-word. |
| 204 | * Returns <code>true</code> if the text contains characters that don't |
| 205 | * fall into the printable ASCII character set or if the text contains a |
| 206 | * 'word' (sequence of non-whitespace characters) longer than 77 characters |
| 207 | * (including characters already used up in the line). |
| 208 | * |
| 209 | * @param text |
| 210 | * text to analyze. |
| 211 | * @param usedCharacters |
| 212 | * number of characters already used up (<code>0 <= usedCharacters <= 50</code>). |
| 213 | * @return <code>true</code> if the specified text has to be encoded into |
| 214 | * an encoded-word, <code>false</code> otherwise. |
| 215 | */ |
| 216 | public static boolean hasToBeEncoded(String text, int usedCharacters) { |
| 217 | if (text == null) |
| 218 | throw new IllegalArgumentException(); |
| 219 | if (usedCharacters < 0 || usedCharacters > MAX_USED_CHARACTERS) |
| 220 | throw new IllegalArgumentException(); |
| 221 | |
| 222 | int nonWhiteSpaceCount = usedCharacters; |
| 223 | |
| 224 | for (int idx = 0; idx < text.length(); idx++) { |
| 225 | char ch = text.charAt(idx); |
| 226 | if (ch == '\t' || ch == ' ') { |
| 227 | nonWhiteSpaceCount = 0; |
| 228 | } else { |
| 229 | nonWhiteSpaceCount++; |
| 230 | if (nonWhiteSpaceCount > 77) { |
| 231 | // Line cannot be folded into multiple lines with no more |
| 232 | // than 78 characters each. Encoding as encoded-words makes |
| 233 | // that possible. One character has to be reserved for |
| 234 | // folding white space; that leaves 77 characters. |
| 235 | return true; |
| 236 | } |
| 237 | |
| 238 | if (ch < 32 || ch >= 127) { |
| 239 | // non-printable ascii character has to be encoded |
| 240 | return true; |
| 241 | } |
| 242 | } |
| 243 | } |
| 244 | |
| 245 | return false; |
| 246 | } |
| 247 | |
| 248 | /** |
| 249 | * Encodes the specified text into an encoded word or a sequence of encoded |
| 250 | * words separated by space. The text is separated into a sequence of |
| 251 | * encoded words if it does not fit in a single one. |
| 252 | * <p> |
| 253 | * The charset to encode the specified text into a byte array and the |
| 254 | * encoding to use for the encoded-word are detected automatically. |
| 255 | * <p> |
| 256 | * This method assumes that zero characters have already been used up in the |
| 257 | * current line. |
| 258 | * |
| 259 | * @param text |
| 260 | * text to encode. |
| 261 | * @param usage |
| 262 | * whether the encoded-word is to be used to replace a text token |
| 263 | * or a word entity (see RFC 822). |
| 264 | * @return the encoded word (or sequence of encoded words if the given text |
| 265 | * does not fit in a single encoded word). |
| 266 | * @see #hasToBeEncoded(String, int) |
| 267 | */ |
| 268 | public static String encodeEncodedWord(String text, Usage usage) { |
| 269 | return encodeEncodedWord(text, usage, 0, null, null); |
| 270 | } |
| 271 | |
| 272 | /** |
| 273 | * Encodes the specified text into an encoded word or a sequence of encoded |
| 274 | * words separated by space. The text is separated into a sequence of |
| 275 | * encoded words if it does not fit in a single one. |
| 276 | * <p> |
| 277 | * The charset to encode the specified text into a byte array and the |
| 278 | * encoding to use for the encoded-word are detected automatically. |
| 279 | * |
| 280 | * @param text |
| 281 | * text to encode. |
| 282 | * @param usage |
| 283 | * whether the encoded-word is to be used to replace a text token |
| 284 | * or a word entity (see RFC 822). |
| 285 | * @param usedCharacters |
| 286 | * number of characters already used up (<code>0 <= usedCharacters <= 50</code>). |
| 287 | * @return the encoded word (or sequence of encoded words if the given text |
| 288 | * does not fit in a single encoded word). |
| 289 | * @see #hasToBeEncoded(String, int) |
| 290 | */ |
| 291 | public static String encodeEncodedWord(String text, Usage usage, |
| 292 | int usedCharacters) { |
| 293 | return encodeEncodedWord(text, usage, usedCharacters, null, null); |
| 294 | } |
| 295 | |
| 296 | /** |
| 297 | * Encodes the specified text into an encoded word or a sequence of encoded |
| 298 | * words separated by space. The text is separated into a sequence of |
| 299 | * encoded words if it does not fit in a single one. |
| 300 | * |
| 301 | * @param text |
| 302 | * text to encode. |
| 303 | * @param usage |
| 304 | * whether the encoded-word is to be used to replace a text token |
| 305 | * or a word entity (see RFC 822). |
| 306 | * @param usedCharacters |
| 307 | * number of characters already used up (<code>0 <= usedCharacters <= 50</code>). |
| 308 | * @param charset |
| 309 | * the Java charset that should be used to encode the specified |
| 310 | * string into a byte array. A suitable charset is detected |
| 311 | * automatically if this parameter is <code>null</code>. |
| 312 | * @param encoding |
| 313 | * the encoding to use for the encoded-word (either B or Q). A |
| 314 | * suitable encoding is automatically chosen if this parameter is |
| 315 | * <code>null</code>. |
| 316 | * @return the encoded word (or sequence of encoded words if the given text |
| 317 | * does not fit in a single encoded word). |
| 318 | * @see #hasToBeEncoded(String, int) |
| 319 | */ |
| 320 | public static String encodeEncodedWord(String text, Usage usage, |
| 321 | int usedCharacters, Charset charset, Encoding encoding) { |
| 322 | if (text == null) |
| 323 | throw new IllegalArgumentException(); |
| 324 | if (usedCharacters < 0 || usedCharacters > MAX_USED_CHARACTERS) |
| 325 | throw new IllegalArgumentException(); |
| 326 | |
| 327 | if (charset == null) |
| 328 | charset = determineCharset(text); |
| 329 | |
| 330 | String mimeCharset = CharsetUtil.toMimeCharset(charset.name()); |
| 331 | if (mimeCharset == null) { |
| 332 | // cannot happen if charset was originally null |
| 333 | throw new IllegalArgumentException("Unsupported charset"); |
| 334 | } |
| 335 | |
| 336 | byte[] bytes = encode(text, charset); |
| 337 | |
| 338 | if (encoding == null) |
| 339 | encoding = determineEncoding(bytes, usage); |
| 340 | |
| 341 | if (encoding == Encoding.B) { |
| 342 | String prefix = ENC_WORD_PREFIX + mimeCharset + "?B?"; |
| 343 | return encodeB(prefix, text, usedCharacters, charset, bytes); |
| 344 | } else { |
| 345 | String prefix = ENC_WORD_PREFIX + mimeCharset + "?Q?"; |
| 346 | return encodeQ(prefix, text, usage, usedCharacters, charset, bytes); |
| 347 | } |
| 348 | } |
| 349 | |
| 350 | /** |
| 351 | * Encodes the specified byte array using the B encoding defined in RFC |
| 352 | * 2047. |
| 353 | * |
| 354 | * @param bytes |
| 355 | * byte array to encode. |
| 356 | * @return encoded string. |
| 357 | */ |
| 358 | public static String encodeB(byte[] bytes) { |
| 359 | StringBuilder sb = new StringBuilder(); |
| 360 | |
| 361 | int idx = 0; |
| 362 | final int end = bytes.length; |
| 363 | for (; idx < end - 2; idx += 3) { |
| 364 | int data = (bytes[idx] & 0xff) << 16 | (bytes[idx + 1] & 0xff) << 8 |
| 365 | | bytes[idx + 2] & 0xff; |
| 366 | sb.append((char) BASE64_TABLE[data >> 18 & 0x3f]); |
| 367 | sb.append((char) BASE64_TABLE[data >> 12 & 0x3f]); |
| 368 | sb.append((char) BASE64_TABLE[data >> 6 & 0x3f]); |
| 369 | sb.append((char) BASE64_TABLE[data & 0x3f]); |
| 370 | } |
| 371 | |
| 372 | if (idx == end - 2) { |
| 373 | int data = (bytes[idx] & 0xff) << 16 | (bytes[idx + 1] & 0xff) << 8; |
| 374 | sb.append((char) BASE64_TABLE[data >> 18 & 0x3f]); |
| 375 | sb.append((char) BASE64_TABLE[data >> 12 & 0x3f]); |
| 376 | sb.append((char) BASE64_TABLE[data >> 6 & 0x3f]); |
| 377 | sb.append((char) BASE64_PAD); |
| 378 | |
| 379 | } else if (idx == end - 1) { |
| 380 | int data = (bytes[idx] & 0xff) << 16; |
| 381 | sb.append((char) BASE64_TABLE[data >> 18 & 0x3f]); |
| 382 | sb.append((char) BASE64_TABLE[data >> 12 & 0x3f]); |
| 383 | sb.append((char) BASE64_PAD); |
| 384 | sb.append((char) BASE64_PAD); |
| 385 | } |
| 386 | |
| 387 | return sb.toString(); |
| 388 | } |
| 389 | |
| 390 | /** |
| 391 | * Encodes the specified byte array using the Q encoding defined in RFC |
| 392 | * 2047. |
| 393 | * |
| 394 | * @param bytes |
| 395 | * byte array to encode. |
| 396 | * @param usage |
| 397 | * whether the encoded-word is to be used to replace a text token |
| 398 | * or a word entity (see RFC 822). |
| 399 | * @return encoded string. |
| 400 | */ |
| 401 | public static String encodeQ(byte[] bytes, Usage usage) { |
| 402 | BitSet qChars = usage == Usage.TEXT_TOKEN ? Q_REGULAR_CHARS |
| 403 | : Q_RESTRICTED_CHARS; |
| 404 | |
| 405 | StringBuilder sb = new StringBuilder(); |
| 406 | |
| 407 | final int end = bytes.length; |
| 408 | for (int idx = 0; idx < end; idx++) { |
| 409 | int v = bytes[idx] & 0xff; |
| 410 | if (v == 32) { |
| 411 | sb.append('_'); |
| 412 | } else if (!qChars.get(v)) { |
| 413 | sb.append('='); |
| 414 | sb.append(hexDigit(v >>> 4)); |
| 415 | sb.append(hexDigit(v & 0xf)); |
| 416 | } else { |
| 417 | sb.append((char) v); |
| 418 | } |
| 419 | } |
| 420 | |
| 421 | return sb.toString(); |
| 422 | } |
| 423 | |
| 424 | /** |
| 425 | * Tests whether the specified string is a token as defined in RFC 2045 |
| 426 | * section 5.1. |
| 427 | * |
| 428 | * @param str |
| 429 | * string to test. |
| 430 | * @return <code>true</code> if the specified string is a RFC 2045 token, |
| 431 | * <code>false</code> otherwise. |
| 432 | */ |
| 433 | public static boolean isToken(String str) { |
| 434 | // token := 1*<any (US-ASCII) CHAR except SPACE, CTLs, or tspecials> |
| 435 | // tspecials := "(" / ")" / "<" / ">" / "@" / "," / ";" / ":" / "\" / |
| 436 | // <"> / "/" / "[" / "]" / "?" / "=" |
| 437 | // CTL := 0.- 31., 127. |
| 438 | |
| 439 | final int length = str.length(); |
| 440 | if (length == 0) |
| 441 | return false; |
| 442 | |
| 443 | for (int idx = 0; idx < length; idx++) { |
| 444 | char ch = str.charAt(idx); |
| 445 | if (!TOKEN_CHARS.get(ch)) |
| 446 | return false; |
| 447 | } |
| 448 | |
| 449 | return true; |
| 450 | } |
| 451 | |
| 452 | private static boolean isAtomPhrase(String str) { |
| 453 | // atom = [CFWS] 1*atext [CFWS] |
| 454 | |
| 455 | boolean containsAText = false; |
| 456 | |
| 457 | final int length = str.length(); |
| 458 | for (int idx = 0; idx < length; idx++) { |
| 459 | char ch = str.charAt(idx); |
| 460 | if (ATEXT_CHARS.get(ch)) { |
| 461 | containsAText = true; |
| 462 | } else if (!CharsetUtil.isWhitespace(ch)) { |
| 463 | return false; |
| 464 | } |
| 465 | } |
| 466 | |
| 467 | return containsAText; |
| 468 | } |
| 469 | |
| 470 | // RFC 5322 section 3.2.3 |
| 471 | private static boolean isDotAtomText(String str) { |
| 472 | // dot-atom-text = 1*atext *("." 1*atext) |
| 473 | // atext = ALPHA / DIGIT / "!" / "#" / "$" / "%" / "&" / "'" / "*" / |
| 474 | // "+" / "-" / "/" / "=" / "?" / "^" / "_" / "`" / "{" / "|" / "}" / "~" |
| 475 | |
| 476 | char prev = '.'; |
| 477 | |
| 478 | final int length = str.length(); |
| 479 | if (length == 0) |
| 480 | return false; |
| 481 | |
| 482 | for (int idx = 0; idx < length; idx++) { |
| 483 | char ch = str.charAt(idx); |
| 484 | |
| 485 | if (ch == '.') { |
| 486 | if (prev == '.' || idx == length - 1) |
| 487 | return false; |
| 488 | } else { |
| 489 | if (!ATEXT_CHARS.get(ch)) |
| 490 | return false; |
| 491 | } |
| 492 | |
| 493 | prev = ch; |
| 494 | } |
| 495 | |
| 496 | return true; |
| 497 | } |
| 498 | |
| 499 | // RFC 5322 section 3.2.4 |
| 500 | private static String quote(String str) { |
| 501 | // quoted-string = [CFWS] DQUOTE *([FWS] qcontent) [FWS] DQUOTE [CFWS] |
| 502 | // qcontent = qtext / quoted-pair |
| 503 | // qtext = %d33 / %d35-91 / %d93-126 |
| 504 | // quoted-pair = ("\" (VCHAR / WSP)) |
| 505 | // VCHAR = %x21-7E |
| 506 | // DQUOTE = %x22 |
| 507 | |
| 508 | String escaped = str.replaceAll("[\\\\\"]", "\\\\$0"); |
| 509 | return "\"" + escaped + "\""; |
| 510 | } |
| 511 | |
| 512 | private static String encodeB(String prefix, String text, |
| 513 | int usedCharacters, Charset charset, byte[] bytes) { |
| 514 | int encodedLength = bEncodedLength(bytes); |
| 515 | |
| 516 | int totalLength = prefix.length() + encodedLength |
| 517 | + ENC_WORD_SUFFIX.length(); |
| 518 | if (totalLength <= ENCODED_WORD_MAX_LENGTH - usedCharacters) { |
| 519 | return prefix + encodeB(bytes) + ENC_WORD_SUFFIX; |
| 520 | } else { |
| 521 | int splitOffset = text.offsetByCodePoints(text.length() / 2, -1); |
| 522 | |
| 523 | String part1 = text.substring(0, splitOffset); |
| 524 | byte[] bytes1 = encode(part1, charset); |
| 525 | String word1 = encodeB(prefix, part1, usedCharacters, charset, |
| 526 | bytes1); |
| 527 | |
| 528 | String part2 = text.substring(splitOffset); |
| 529 | byte[] bytes2 = encode(part2, charset); |
| 530 | String word2 = encodeB(prefix, part2, 0, charset, bytes2); |
| 531 | |
| 532 | return word1 + " " + word2; |
| 533 | } |
| 534 | } |
| 535 | |
| 536 | private static int bEncodedLength(byte[] bytes) { |
| 537 | return (bytes.length + 2) / 3 * 4; |
| 538 | } |
| 539 | |
| 540 | private static String encodeQ(String prefix, String text, Usage usage, |
| 541 | int usedCharacters, Charset charset, byte[] bytes) { |
| 542 | int encodedLength = qEncodedLength(bytes, usage); |
| 543 | |
| 544 | int totalLength = prefix.length() + encodedLength |
| 545 | + ENC_WORD_SUFFIX.length(); |
| 546 | if (totalLength <= ENCODED_WORD_MAX_LENGTH - usedCharacters) { |
| 547 | return prefix + encodeQ(bytes, usage) + ENC_WORD_SUFFIX; |
| 548 | } else { |
| 549 | int splitOffset = text.offsetByCodePoints(text.length() / 2, -1); |
| 550 | |
| 551 | String part1 = text.substring(0, splitOffset); |
| 552 | byte[] bytes1 = encode(part1, charset); |
| 553 | String word1 = encodeQ(prefix, part1, usage, usedCharacters, |
| 554 | charset, bytes1); |
| 555 | |
| 556 | String part2 = text.substring(splitOffset); |
| 557 | byte[] bytes2 = encode(part2, charset); |
| 558 | String word2 = encodeQ(prefix, part2, usage, 0, charset, bytes2); |
| 559 | |
| 560 | return word1 + " " + word2; |
| 561 | } |
| 562 | } |
| 563 | |
| 564 | private static int qEncodedLength(byte[] bytes, Usage usage) { |
| 565 | BitSet qChars = usage == Usage.TEXT_TOKEN ? Q_REGULAR_CHARS |
| 566 | : Q_RESTRICTED_CHARS; |
| 567 | |
| 568 | int count = 0; |
| 569 | |
| 570 | for (int idx = 0; idx < bytes.length; idx++) { |
| 571 | int v = bytes[idx] & 0xff; |
| 572 | if (v == 32) { |
| 573 | count++; |
| 574 | } else if (!qChars.get(v)) { |
| 575 | count += 3; |
| 576 | } else { |
| 577 | count++; |
| 578 | } |
| 579 | } |
| 580 | |
| 581 | return count; |
| 582 | } |
| 583 | |
| 584 | private static byte[] encode(String text, Charset charset) { |
| 585 | ByteBuffer buffer = charset.encode(text); |
| 586 | byte[] bytes = new byte[buffer.limit()]; |
| 587 | buffer.get(bytes); |
| 588 | return bytes; |
| 589 | } |
| 590 | |
| 591 | private static Charset determineCharset(String text) { |
| 592 | // it is an important property of iso-8859-1 that it directly maps |
| 593 | // unicode code points 0000 to 00ff to byte values 00 to ff. |
| 594 | boolean ascii = true; |
| 595 | final int len = text.length(); |
| 596 | for (int index = 0; index < len; index++) { |
| 597 | char ch = text.charAt(index); |
| 598 | if (ch > 0xff) { |
| 599 | return CharsetUtil.UTF_8; |
| 600 | } |
| 601 | if (ch > 0x7f) { |
| 602 | ascii = false; |
| 603 | } |
| 604 | } |
| 605 | return ascii ? CharsetUtil.US_ASCII : CharsetUtil.ISO_8859_1; |
| 606 | } |
| 607 | |
| 608 | private static Encoding determineEncoding(byte[] bytes, Usage usage) { |
| 609 | if (bytes.length == 0) |
| 610 | return Encoding.Q; |
| 611 | |
| 612 | BitSet qChars = usage == Usage.TEXT_TOKEN ? Q_REGULAR_CHARS |
| 613 | : Q_RESTRICTED_CHARS; |
| 614 | |
| 615 | int qEncoded = 0; |
| 616 | for (int i = 0; i < bytes.length; i++) { |
| 617 | int v = bytes[i] & 0xff; |
| 618 | if (v != 32 && !qChars.get(v)) { |
| 619 | qEncoded++; |
| 620 | } |
| 621 | } |
| 622 | |
| 623 | int percentage = qEncoded * 100 / bytes.length; |
| 624 | return percentage > 30 ? Encoding.B : Encoding.Q; |
| 625 | } |
| 626 | |
| 627 | private static char hexDigit(int i) { |
| 628 | return i < 10 ? (char) (i + '0') : (char) (i - 10 + 'A'); |
| 629 | } |
| 630 | } |