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Diffstat (limited to 'src/org/apache/james/mime4j/codec/EncoderUtil.java')
| -rw-r--r-- | src/org/apache/james/mime4j/codec/EncoderUtil.java | 630 |
1 files changed, 630 insertions, 0 deletions
diff --git a/src/org/apache/james/mime4j/codec/EncoderUtil.java b/src/org/apache/james/mime4j/codec/EncoderUtil.java new file mode 100644 index 000000000..6841bc998 --- /dev/null +++ b/src/org/apache/james/mime4j/codec/EncoderUtil.java @@ -0,0 +1,630 @@ +/**************************************************************** + * Licensed to the Apache Software Foundation (ASF) under one * + * or more contributor license agreements. See the NOTICE file * + * distributed with this work for additional information * + * regarding copyright ownership. The ASF licenses this file * + * to you under the Apache License, Version 2.0 (the * + * "License"); you may not use this file except in compliance * + * with the License. You may obtain a copy of the License at * + * * + * http://www.apache.org/licenses/LICENSE-2.0 * + * * + * Unless required by applicable law or agreed to in writing, * + * software distributed under the License is distributed on an * + * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY * + * KIND, either express or implied. See the License for the * + * specific language governing permissions and limitations * + * under the License. * + ****************************************************************/ + +package org.apache.james.mime4j.codec; + +import java.nio.ByteBuffer; +import java.nio.charset.Charset; +import java.util.BitSet; +import java.util.Locale; + +import org.apache.james.mime4j.util.CharsetUtil; + +/** + * ANDROID: THIS CLASS IS COPIED FROM A NEWER VERSION OF MIME4J + */ + +/** + * Static methods for encoding header field values. This includes encoded-words + * as defined in <a href='http://www.faqs.org/rfcs/rfc2047.html'>RFC 2047</a> + * or display-names of an e-mail address, for example. + * + */ +public class EncoderUtil { + + // This array is a lookup table that translates 6-bit positive integer index + // values into their "Base64 Alphabet" equivalents as specified in Table 1 + // of RFC 2045. + // ANDROID: THIS TABLE IS COPIED FROM BASE64OUTPUTSTREAM + static final byte[] BASE64_TABLE = { 'A', 'B', 'C', 'D', 'E', 'F', + 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', + 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', + 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', + 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', + '6', '7', '8', '9', '+', '/' }; + + // Byte used to pad output. + private static final byte BASE64_PAD = '='; + + private static final BitSet Q_REGULAR_CHARS = initChars("=_?"); + + private static final BitSet Q_RESTRICTED_CHARS = initChars("=_?\"#$%&'(),.:;<>@[\\]^`{|}~"); + + private static final int MAX_USED_CHARACTERS = 50; + + private static final String ENC_WORD_PREFIX = "=?"; + private static final String ENC_WORD_SUFFIX = "?="; + + private static final int ENCODED_WORD_MAX_LENGTH = 75; // RFC 2047 + + private static final BitSet TOKEN_CHARS = initChars("()<>@,;:\\\"/[]?="); + + private static final BitSet ATEXT_CHARS = initChars("()<>@.,;:\\\"[]"); + + private static BitSet initChars(String specials) { + BitSet bs = new BitSet(128); + for (char ch = 33; ch < 127; ch++) { + if (specials.indexOf(ch) == -1) { + bs.set(ch); + } + } + return bs; + } + + /** + * Selects one of the two encodings specified in RFC 2047. + */ + public enum Encoding { + /** The B encoding (identical to base64 defined in RFC 2045). */ + B, + /** The Q encoding (similar to quoted-printable defined in RFC 2045). */ + Q + } + + /** + * Indicates the intended usage of an encoded word. + */ + public enum Usage { + /** + * Encoded word is used to replace a 'text' token in any Subject or + * Comments header field. + */ + TEXT_TOKEN, + /** + * Encoded word is used to replace a 'word' entity within a 'phrase', + * for example, one that precedes an address in a From, To, or Cc + * header. + */ + WORD_ENTITY + } + + private EncoderUtil() { + } + + /** + * Encodes the display-name portion of an address. See <a + * href='http://www.faqs.org/rfcs/rfc5322.html'>RFC 5322</a> section 3.4 + * and <a href='http://www.faqs.org/rfcs/rfc2047.html'>RFC 2047</a> section + * 5.3. The specified string should not be folded. + * + * @param displayName + * display-name to encode. + * @return encoded display-name. + */ + public static String encodeAddressDisplayName(String displayName) { + // display-name = phrase + // phrase = 1*( encoded-word / word ) + // word = atom / quoted-string + // atom = [CFWS] 1*atext [CFWS] + // CFWS = comment or folding white space + + if (isAtomPhrase(displayName)) { + return displayName; + } else if (hasToBeEncoded(displayName, 0)) { + return encodeEncodedWord(displayName, Usage.WORD_ENTITY); + } else { + return quote(displayName); + } + } + + /** + * Encodes the local part of an address specification as described in RFC + * 5322 section 3.4.1. Leading and trailing CFWS should have been removed + * before calling this method. The specified string should not contain any + * illegal (control or non-ASCII) characters. + * + * @param localPart + * the local part to encode + * @return the encoded local part. + */ + public static String encodeAddressLocalPart(String localPart) { + // local-part = dot-atom / quoted-string + // dot-atom = [CFWS] dot-atom-text [CFWS] + // CFWS = comment or folding white space + + if (isDotAtomText(localPart)) { + return localPart; + } else { + return quote(localPart); + } + } + + /** + * Encodes the specified strings into a header parameter as described in RFC + * 2045 section 5.1 and RFC 2183 section 2. The specified strings should not + * contain any illegal (control or non-ASCII) characters. + * + * @param name + * parameter name. + * @param value + * parameter value. + * @return encoded result. + */ + public static String encodeHeaderParameter(String name, String value) { + name = name.toLowerCase(Locale.US); + + // value := token / quoted-string + if (isToken(value)) { + return name + "=" + value; + } else { + return name + "=" + quote(value); + } + } + + /** + * Shortcut method that encodes the specified text into an encoded-word if + * the text has to be encoded. + * + * @param text + * text to encode. + * @param usage + * whether the encoded-word is to be used to replace a text token + * or a word entity (see RFC 822). + * @param usedCharacters + * number of characters already used up (<code>0 <= usedCharacters <= 50</code>). + * @return the specified text if encoding is not necessary or an encoded + * word or a sequence of encoded words otherwise. + */ + public static String encodeIfNecessary(String text, Usage usage, + int usedCharacters) { + if (hasToBeEncoded(text, usedCharacters)) + return encodeEncodedWord(text, usage, usedCharacters); + else + return text; + } + + /** + * Determines if the specified string has to encoded into an encoded-word. + * Returns <code>true</code> if the text contains characters that don't + * fall into the printable ASCII character set or if the text contains a + * 'word' (sequence of non-whitespace characters) longer than 77 characters + * (including characters already used up in the line). + * + * @param text + * text to analyze. + * @param usedCharacters + * number of characters already used up (<code>0 <= usedCharacters <= 50</code>). + * @return <code>true</code> if the specified text has to be encoded into + * an encoded-word, <code>false</code> otherwise. + */ + public static boolean hasToBeEncoded(String text, int usedCharacters) { + if (text == null) + throw new IllegalArgumentException(); + if (usedCharacters < 0 || usedCharacters > MAX_USED_CHARACTERS) + throw new IllegalArgumentException(); + + int nonWhiteSpaceCount = usedCharacters; + + for (int idx = 0; idx < text.length(); idx++) { + char ch = text.charAt(idx); + if (ch == '\t' || ch == ' ') { + nonWhiteSpaceCount = 0; + } else { + nonWhiteSpaceCount++; + if (nonWhiteSpaceCount > 77) { + // Line cannot be folded into multiple lines with no more + // than 78 characters each. Encoding as encoded-words makes + // that possible. One character has to be reserved for + // folding white space; that leaves 77 characters. + return true; + } + + if (ch < 32 || ch >= 127) { + // non-printable ascii character has to be encoded + return true; + } + } + } + + return false; + } + + /** + * Encodes the specified text into an encoded word or a sequence of encoded + * words separated by space. The text is separated into a sequence of + * encoded words if it does not fit in a single one. + * <p> + * The charset to encode the specified text into a byte array and the + * encoding to use for the encoded-word are detected automatically. + * <p> + * This method assumes that zero characters have already been used up in the + * current line. + * + * @param text + * text to encode. + * @param usage + * whether the encoded-word is to be used to replace a text token + * or a word entity (see RFC 822). + * @return the encoded word (or sequence of encoded words if the given text + * does not fit in a single encoded word). + * @see #hasToBeEncoded(String, int) + */ + public static String encodeEncodedWord(String text, Usage usage) { + return encodeEncodedWord(text, usage, 0, null, null); + } + + /** + * Encodes the specified text into an encoded word or a sequence of encoded + * words separated by space. The text is separated into a sequence of + * encoded words if it does not fit in a single one. + * <p> + * The charset to encode the specified text into a byte array and the + * encoding to use for the encoded-word are detected automatically. + * + * @param text + * text to encode. + * @param usage + * whether the encoded-word is to be used to replace a text token + * or a word entity (see RFC 822). + * @param usedCharacters + * number of characters already used up (<code>0 <= usedCharacters <= 50</code>). + * @return the encoded word (or sequence of encoded words if the given text + * does not fit in a single encoded word). + * @see #hasToBeEncoded(String, int) + */ + public static String encodeEncodedWord(String text, Usage usage, + int usedCharacters) { + return encodeEncodedWord(text, usage, usedCharacters, null, null); + } + + /** + * Encodes the specified text into an encoded word or a sequence of encoded + * words separated by space. The text is separated into a sequence of + * encoded words if it does not fit in a single one. + * + * @param text + * text to encode. + * @param usage + * whether the encoded-word is to be used to replace a text token + * or a word entity (see RFC 822). + * @param usedCharacters + * number of characters already used up (<code>0 <= usedCharacters <= 50</code>). + * @param charset + * the Java charset that should be used to encode the specified + * string into a byte array. A suitable charset is detected + * automatically if this parameter is <code>null</code>. + * @param encoding + * the encoding to use for the encoded-word (either B or Q). A + * suitable encoding is automatically chosen if this parameter is + * <code>null</code>. + * @return the encoded word (or sequence of encoded words if the given text + * does not fit in a single encoded word). + * @see #hasToBeEncoded(String, int) + */ + public static String encodeEncodedWord(String text, Usage usage, + int usedCharacters, Charset charset, Encoding encoding) { + if (text == null) + throw new IllegalArgumentException(); + if (usedCharacters < 0 || usedCharacters > MAX_USED_CHARACTERS) + throw new IllegalArgumentException(); + + if (charset == null) + charset = determineCharset(text); + + String mimeCharset = CharsetUtil.toMimeCharset(charset.name()); + if (mimeCharset == null) { + // cannot happen if charset was originally null + throw new IllegalArgumentException("Unsupported charset"); + } + + byte[] bytes = encode(text, charset); + + if (encoding == null) + encoding = determineEncoding(bytes, usage); + + if (encoding == Encoding.B) { + String prefix = ENC_WORD_PREFIX + mimeCharset + "?B?"; + return encodeB(prefix, text, usedCharacters, charset, bytes); + } else { + String prefix = ENC_WORD_PREFIX + mimeCharset + "?Q?"; + return encodeQ(prefix, text, usage, usedCharacters, charset, bytes); + } + } + + /** + * Encodes the specified byte array using the B encoding defined in RFC + * 2047. + * + * @param bytes + * byte array to encode. + * @return encoded string. + */ + public static String encodeB(byte[] bytes) { + StringBuilder sb = new StringBuilder(); + + int idx = 0; + final int end = bytes.length; + for (; idx < end - 2; idx += 3) { + int data = (bytes[idx] & 0xff) << 16 | (bytes[idx + 1] & 0xff) << 8 + | bytes[idx + 2] & 0xff; + sb.append((char) BASE64_TABLE[data >> 18 & 0x3f]); + sb.append((char) BASE64_TABLE[data >> 12 & 0x3f]); + sb.append((char) BASE64_TABLE[data >> 6 & 0x3f]); + sb.append((char) BASE64_TABLE[data & 0x3f]); + } + + if (idx == end - 2) { + int data = (bytes[idx] & 0xff) << 16 | (bytes[idx + 1] & 0xff) << 8; + sb.append((char) BASE64_TABLE[data >> 18 & 0x3f]); + sb.append((char) BASE64_TABLE[data >> 12 & 0x3f]); + sb.append((char) BASE64_TABLE[data >> 6 & 0x3f]); + sb.append((char) BASE64_PAD); + + } else if (idx == end - 1) { + int data = (bytes[idx] & 0xff) << 16; + sb.append((char) BASE64_TABLE[data >> 18 & 0x3f]); + sb.append((char) BASE64_TABLE[data >> 12 & 0x3f]); + sb.append((char) BASE64_PAD); + sb.append((char) BASE64_PAD); + } + + return sb.toString(); + } + + /** + * Encodes the specified byte array using the Q encoding defined in RFC + * 2047. + * + * @param bytes + * byte array to encode. + * @param usage + * whether the encoded-word is to be used to replace a text token + * or a word entity (see RFC 822). + * @return encoded string. + */ + public static String encodeQ(byte[] bytes, Usage usage) { + BitSet qChars = usage == Usage.TEXT_TOKEN ? Q_REGULAR_CHARS + : Q_RESTRICTED_CHARS; + + StringBuilder sb = new StringBuilder(); + + final int end = bytes.length; + for (int idx = 0; idx < end; idx++) { + int v = bytes[idx] & 0xff; + if (v == 32) { + sb.append('_'); + } else if (!qChars.get(v)) { + sb.append('='); + sb.append(hexDigit(v >>> 4)); + sb.append(hexDigit(v & 0xf)); + } else { + sb.append((char) v); + } + } + + return sb.toString(); + } + + /** + * Tests whether the specified string is a token as defined in RFC 2045 + * section 5.1. + * + * @param str + * string to test. + * @return <code>true</code> if the specified string is a RFC 2045 token, + * <code>false</code> otherwise. + */ + public static boolean isToken(String str) { + // token := 1*<any (US-ASCII) CHAR except SPACE, CTLs, or tspecials> + // tspecials := "(" / ")" / "<" / ">" / "@" / "," / ";" / ":" / "\" / + // <"> / "/" / "[" / "]" / "?" / "=" + // CTL := 0.- 31., 127. + + final int length = str.length(); + if (length == 0) + return false; + + for (int idx = 0; idx < length; idx++) { + char ch = str.charAt(idx); + if (!TOKEN_CHARS.get(ch)) + return false; + } + + return true; + } + + private static boolean isAtomPhrase(String str) { + // atom = [CFWS] 1*atext [CFWS] + + boolean containsAText = false; + + final int length = str.length(); + for (int idx = 0; idx < length; idx++) { + char ch = str.charAt(idx); + if (ATEXT_CHARS.get(ch)) { + containsAText = true; + } else if (!CharsetUtil.isWhitespace(ch)) { + return false; + } + } + + return containsAText; + } + + // RFC 5322 section 3.2.3 + private static boolean isDotAtomText(String str) { + // dot-atom-text = 1*atext *("." 1*atext) + // atext = ALPHA / DIGIT / "!" / "#" / "$" / "%" / "&" / "'" / "*" / + // "+" / "-" / "/" / "=" / "?" / "^" / "_" / "`" / "{" / "|" / "}" / "~" + + char prev = '.'; + + final int length = str.length(); + if (length == 0) + return false; + + for (int idx = 0; idx < length; idx++) { + char ch = str.charAt(idx); + + if (ch == '.') { + if (prev == '.' || idx == length - 1) + return false; + } else { + if (!ATEXT_CHARS.get(ch)) + return false; + } + + prev = ch; + } + + return true; + } + + // RFC 5322 section 3.2.4 + private static String quote(String str) { + // quoted-string = [CFWS] DQUOTE *([FWS] qcontent) [FWS] DQUOTE [CFWS] + // qcontent = qtext / quoted-pair + // qtext = %d33 / %d35-91 / %d93-126 + // quoted-pair = ("\" (VCHAR / WSP)) + // VCHAR = %x21-7E + // DQUOTE = %x22 + + String escaped = str.replaceAll("[\\\\\"]", "\\\\$0"); + return "\"" + escaped + "\""; + } + + private static String encodeB(String prefix, String text, + int usedCharacters, Charset charset, byte[] bytes) { + int encodedLength = bEncodedLength(bytes); + + int totalLength = prefix.length() + encodedLength + + ENC_WORD_SUFFIX.length(); + if (totalLength <= ENCODED_WORD_MAX_LENGTH - usedCharacters) { + return prefix + encodeB(bytes) + ENC_WORD_SUFFIX; + } else { + int splitOffset = text.offsetByCodePoints(text.length() / 2, -1); + + String part1 = text.substring(0, splitOffset); + byte[] bytes1 = encode(part1, charset); + String word1 = encodeB(prefix, part1, usedCharacters, charset, + bytes1); + + String part2 = text.substring(splitOffset); + byte[] bytes2 = encode(part2, charset); + String word2 = encodeB(prefix, part2, 0, charset, bytes2); + + return word1 + " " + word2; + } + } + + private static int bEncodedLength(byte[] bytes) { + return (bytes.length + 2) / 3 * 4; + } + + private static String encodeQ(String prefix, String text, Usage usage, + int usedCharacters, Charset charset, byte[] bytes) { + int encodedLength = qEncodedLength(bytes, usage); + + int totalLength = prefix.length() + encodedLength + + ENC_WORD_SUFFIX.length(); + if (totalLength <= ENCODED_WORD_MAX_LENGTH - usedCharacters) { + return prefix + encodeQ(bytes, usage) + ENC_WORD_SUFFIX; + } else { + int splitOffset = text.offsetByCodePoints(text.length() / 2, -1); + + String part1 = text.substring(0, splitOffset); + byte[] bytes1 = encode(part1, charset); + String word1 = encodeQ(prefix, part1, usage, usedCharacters, + charset, bytes1); + + String part2 = text.substring(splitOffset); + byte[] bytes2 = encode(part2, charset); + String word2 = encodeQ(prefix, part2, usage, 0, charset, bytes2); + + return word1 + " " + word2; + } + } + + private static int qEncodedLength(byte[] bytes, Usage usage) { + BitSet qChars = usage == Usage.TEXT_TOKEN ? Q_REGULAR_CHARS + : Q_RESTRICTED_CHARS; + + int count = 0; + + for (int idx = 0; idx < bytes.length; idx++) { + int v = bytes[idx] & 0xff; + if (v == 32) { + count++; + } else if (!qChars.get(v)) { + count += 3; + } else { + count++; + } + } + + return count; + } + + private static byte[] encode(String text, Charset charset) { + ByteBuffer buffer = charset.encode(text); + byte[] bytes = new byte[buffer.limit()]; + buffer.get(bytes); + return bytes; + } + + private static Charset determineCharset(String text) { + // it is an important property of iso-8859-1 that it directly maps + // unicode code points 0000 to 00ff to byte values 00 to ff. + boolean ascii = true; + final int len = text.length(); + for (int index = 0; index < len; index++) { + char ch = text.charAt(index); + if (ch > 0xff) { + return CharsetUtil.UTF_8; + } + if (ch > 0x7f) { + ascii = false; + } + } + return ascii ? CharsetUtil.US_ASCII : CharsetUtil.ISO_8859_1; + } + + private static Encoding determineEncoding(byte[] bytes, Usage usage) { + if (bytes.length == 0) + return Encoding.Q; + + BitSet qChars = usage == Usage.TEXT_TOKEN ? Q_REGULAR_CHARS + : Q_RESTRICTED_CHARS; + + int qEncoded = 0; + for (int i = 0; i < bytes.length; i++) { + int v = bytes[i] & 0xff; + if (v != 32 && !qChars.get(v)) { + qEncoded++; + } + } + + int percentage = qEncoded * 100 / bytes.length; + return percentage > 30 ? Encoding.B : Encoding.Q; + } + + private static char hexDigit(int i) { + return i < 10 ? (char) (i + '0') : (char) (i - 10 + 'A'); + } +} |