us.monoid.util.EncoderUtil Maven / Gradle / Ivy
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package us.monoid.util;
/****************************************************************
* 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. *
****************************************************************/
import java.nio.ByteBuffer;
import java.nio.charset.Charset;
import java.util.BitSet;
import java.util.Locale;
/**
* Stolen from Mime4j project.
*/
/**
* Static methods for encoding header field values. This includes encoded-words
* as defined in RFC 2047 or
* display-names of an e-mail address, for example.
*
*/
public class EncoderUtil {
public static final Charset US_ASCII = Charset.forName("US-ASCII");
// 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 RFC 5322 section 3.4 and
* RFC 2047 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 (
* 0 <= usedCharacters <= 50).
* @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 true 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 (
* 0 <= usedCharacters <= 50).
* @return true if the specified text has to be encoded into an
* encoded-word, false 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.
*
* The charset to encode the specified text into a byte array and the encoding
* to use for the encoded-word are detected automatically.
*
* 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.
*
* 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 (
* 0 <= usedCharacters <= 50).
* @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 (
* 0 <= usedCharacters <= 50).
* @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 null.
* @param encoding
* the encoding to use for the encoded-word (either B or Q). A
* suitable encoding is automatically chosen if this parameter is
* null.
* @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 = charset.name(); // no canonical names needed
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 true if the specified string is a RFC 2045 token,
* false otherwise.
*/
public static boolean isToken(String str) {
// token := 1*
// 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 (Character.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 Charset.forName("UTF-8");
}
if (ch > 0x7f) {
ascii = false;
}
}
return ascii ? Charset.forName("US-ASCII") : Charset.forName("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');
}
}