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Add support for RFC 2047 non-compliant splitting of UTF-8 encoded characters

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This commit is contained in:
Philip Whitehouse 2017-08-31 13:28:50 +01:00 committed by Philip Whitehouse
parent 79582f12e4
commit f88c3594fc
2 changed files with 78 additions and 14 deletions
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77
k9mail-library/src/main/java/com/fsck/k9/mail/internet/DecoderUtil.java
View file

@ -21,6 +21,13 @@ import timber.log.Timber;
* it has to be determined with the sender address, the mailer and so on.
*/
class DecoderUtil {
private static class EncodedWord {
private String charset;
private String encoding;
private String encodedText;
}
/**
* Decodes an encoded word encoded with the 'B' encoding (described in
* RFC 2047) found in a header field body.
@ -93,14 +100,18 @@ class DecoderUtil {
return body;
}
EncodedWord previousWord = null;
int previousEnd = 0;
boolean previousWasEncoded = false;
StringBuilder sb = new StringBuilder();
while (true) {
int begin = body.indexOf("=?", previousEnd);
if (begin == -1) {
if (previousWord != null) {
sb.append(decodeEncodedWord(previousWord));
previousWord = null;
}
sb.append(body.substring(previousEnd));
return sb.toString();
}
@ -110,18 +121,30 @@ class DecoderUtil {
// to find the two '?' in the "header", before looking for the final "?=".
int qm1 = body.indexOf('?', begin + 2);
if (qm1 == -1) {
if (previousWord != null) {
sb.append(decodeEncodedWord(previousWord));
previousWord = null;
}
sb.append(body.substring(previousEnd));
return sb.toString();
}
int qm2 = body.indexOf('?', qm1 + 1);
if (qm2 == -1) {
if (previousWord != null) {
sb.append(decodeEncodedWord(previousWord));
previousWord = null;
}
sb.append(body.substring(previousEnd));
return sb.toString();
}
int end = body.indexOf("?=", qm2 + 1);
if (end == -1) {
if (previousWord != null) {
sb.append(decodeEncodedWord(previousWord));
previousWord = null;
}
sb.append(body.substring(previousEnd));
return sb.toString();
}
@ -129,24 +152,52 @@ class DecoderUtil {
String sep = body.substring(previousEnd, begin);
String decoded = decodeEncodedWord(body, begin, end, message);
if (decoded == null) {
EncodedWord word = extractEncodedWord(body, begin, end, message);
if (word == null) {
if (previousWord != null) {
sb.append(decodeEncodedWord(previousWord));
sb.append(sep);
previousWord = null;
}
} else if (previousWord != null) {
if (previousWord.encoding.equals(word.encoding) && previousWord.charset.equals(word.charset)) {
previousWord.encodedText += word.encodedText;
} else {
sb.append(decodeEncodedWord(previousWord));
sb.append(sep);
previousWord = word;
}
} else {
previousWord = word;
}
if (previousWord == null) {
sb.append(sep);
sb.append(body.substring(begin, end));
} else {
if (!previousWasEncoded || !CharsetUtil.isWhitespace(sep)) {
sb.append(sep);
}
sb.append(decoded);
}
previousEnd = end;
previousWasEncoded = decoded != null;
}
}
// return null on error
private static String decodeEncodedWord(String body, int begin, int end, Message message) {
return decodeEncodedWord(extractEncodedWord(body, begin, end, message));
}
private static String decodeEncodedWord(EncodedWord word) {
if (word.encoding.equals("Q")) {
return decodeQ(word.encodedText, word.charset);
} else if (word.encoding.equals("B")) {
return DecoderUtil.decodeB(word.encodedText, word.charset);
} else {
Timber.w("Warning: Unknown encoding '%s'", word.encoding);
return null;
}
}
private static EncodedWord extractEncodedWord(String body, int begin, int end, Message message) {
int qm1 = body.indexOf('?', begin + 2);
if (qm1 == end - 2)
return null;
@ -171,13 +222,17 @@ class DecoderUtil {
return null;
}
EncodedWord encodedWord = new EncodedWord();
encodedWord.charset = charset;
if (encoding.equalsIgnoreCase("Q")) {
return decodeQ(encodedText, charset);
encodedWord.encoding = "Q";
} else if (encoding.equalsIgnoreCase("B")) {
return DecoderUtil.decodeB(encodedText, charset);
encodedWord.encoding = "B";
} else {
Timber.w("Warning: Unknown encoding in encoded word '%s'", body.substring(begin, end));
return null;
}
encodedWord.encodedText = encodedText;
return encodedWord;
}
}

15
k9mail-library/src/test/java/com/fsck/k9/mail/internet/DecoderUtilTest.java
View file

@ -169,10 +169,19 @@ public class DecoderUtilTest {
}
@Test
public void decodeEncodedWords_withMultipleEncodedSections_decodesAll() {
public void decodeEncodedWords_withMultipleEncodedSections_decodesBoth() {
body = "=?us-ascii?q?abc?= =?us-ascii?q?def?=";
expect = "abcdef";
message = null;
assertEquals(expect, DecoderUtil.decodeEncodedWords(body, message));
}
@Test
public void decodeEncodedWords_withMultipleEncodedSections_decodesSequentialSectionTogether() {
//Splitting mid-character is RFC2047 non-compliant but seen in practice.
body = "=?utf-8?B?5Liq5Lq66YKu566xOkJVRyAjMzAyNDY6OumCruS7tuato+aWh+mZhOS7tuWQ?=\n" +
"=?utf-8?B?jeensOecgeeVpeaYvuekuuS8mOWMlg==?=";
expect = "个人邮箱:BUG #30246::邮件正文附件<E99984><E4BBB6>称省略显示优化";
expect = "个人邮箱:BUG #30246::邮件正文附件名称省略显示优化";
message = null;
assertEquals(expect, DecoderUtil.decodeEncodedWords(body, message));
}
@ -181,7 +190,7 @@ public class DecoderUtilTest {
public void decodeEncodedWords_withGB2312_decodes_correctly() {
body = "=?gb2312?B?Obv9t9az6cnu29rHsLqju6rHyLPHSlfN8rrAvsa16qOsuPzT0DIwvNIzOTnU?= " +
"=?gb2312?B?qr6r0aG439DHytTLr77Gteq1yMTjwLSjoaOoQUSjqQ?=";
expect = "9积分抽深圳前海华侨城JW万豪酒店，更有20家399<EFBFBD><EFBFBD>精选高星试睡酒店等你来！（AD<EFBFBD>";
expect = "9积分抽深圳前海华侨城JW万豪酒店，更有20家399元精选高星试睡酒店等你来！（AD<EFBFBD>";
message = null;
assertEquals(expect, DecoderUtil.decodeEncodedWords(body, message));
}