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Code Issues Releases Wiki Activity

Auto recognize ISO-2022-JP

This commit is contained in:
M66B 2020-10-09 17:43:02 +02:00
parent b49208083e
commit cd1556470b
3 changed files with 127 additions and 51 deletions
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118
app/src/main/java/eu/faircode/email/CharsetHelper.java Normal file
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@ -0,0 +1,118 @@
package eu.faircode.email;
/*
This file is part of FairEmail.
FairEmail is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
FairEmail is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with FairEmail. If not, see <http://www.gnu.org/licenses/>.
Copyright 2018-2020 by Marcel Bokhorst (M66B)
*/
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.nio.charset.UnsupportedCharsetException;
class CharsetHelper {
static boolean isUTF8(String text) {
// Get extended ASCII characters
byte[] octets = text.getBytes(StandardCharsets.ISO_8859_1);
int bytes;
for (int i = 0; i < octets.length; i++) {
if ((octets[i] & 0b10000000) == 0b00000000)
bytes = 1;
else if ((octets[i] & 0b11100000) == 0b11000000)
bytes = 2;
else if ((octets[i] & 0b11110000) == 0b11100000)
bytes = 3;
else if ((octets[i] & 0b11111000) == 0b11110000)
bytes = 4;
else if ((octets[i] & 0b11111100) == 0b11111000)
bytes = 5;
else if ((octets[i] & 0b11111110) == 0b11111100)
bytes = 6;
else
return false;
if (i + bytes > octets.length)
return false;
while (--bytes > 0)
if ((octets[++i] & 0b11000000) != 0b10000000)
return false;
}
return true;
}
static boolean isISO8859(String text) {
// https://en.wikipedia.org/wiki/ISO/IEC_8859-1
int c;
byte[] octets = text.getBytes(StandardCharsets.ISO_8859_1);
for (byte b : octets) {
c = b & 0xFF;
if (c < 32)
return false;
if (c >= 127 && c < 160)
return false;
}
return true;
}
static boolean isISO2022JP(String text) {
// https://en.wikipedia.org/wiki/ISO/IEC_2022
// https://www.sljfaq.org/afaq/encodings.html#encodings-ISO-2022-JP
try {
Charset.forName("ISO-2022-JP");
} catch (UnsupportedCharsetException ex) {
return false;
}
int c;
int escapes = 0;
boolean escaped = false;
boolean parenthesis = false;
boolean dollar = false;
byte[] octets = text.getBytes(StandardCharsets.ISO_8859_1);
for (byte b : octets) {
c = b & 0xFF;
if (c > 0x7F)
return false;
if (escaped) {
escaped = false;
if (c == '(')
parenthesis = true;
else if (c == '$')
dollar = true;
} else if (parenthesis) {
parenthesis = false;
if (c == 'B' || c == 'J')
escapes++;
} else if (dollar) {
dollar = false;
if (c == '@' || c == 'B')
escapes++;
} else if (c == 0x1B)
escaped = true;
if (escapes >= 3)
return true;
}
return false;
}
}

46
app/src/main/java/eu/faircode/email/Helper.java
View File

@ -961,52 +961,6 @@ public class Helper {
return false;
}
static boolean isUTF8(String text) {
// Get extended ASCII characters
byte[] octets = text.getBytes(StandardCharsets.ISO_8859_1);
int bytes;
for (int i = 0; i < octets.length; i++) {
if ((octets[i] & 0b10000000) == 0b00000000)
bytes = 1;
else if ((octets[i] & 0b11100000) == 0b11000000)
bytes = 2;
else if ((octets[i] & 0b11110000) == 0b11100000)
bytes = 3;
else if ((octets[i] & 0b11111000) == 0b11110000)
bytes = 4;
else if ((octets[i] & 0b11111100) == 0b11111000)
bytes = 5;
else if ((octets[i] & 0b11111110) == 0b11111100)
bytes = 6;
else
return false;
if (i + bytes > octets.length)
return false;
while (--bytes > 0)
if ((octets[++i] & 0b11000000) != 0b10000000)
return false;
}
return true;
}
static boolean isISO8859(String text) {
// https://en.wikipedia.org/wiki/ISO/IEC_8859-1
int c;
byte[] octets = text.getBytes(StandardCharsets.ISO_8859_1);
for (byte b : octets) {
c = b & 0xFF;
if (c < 32)
return false;
if (c >= 127 && c < 160)
return false;
}
return true;
}
static boolean isSingleScript(String s) {
// https://en.wikipedia.org/wiki/IDN_homograph_attack
if (Build.VERSION.SDK_INT < Build.VERSION_CODES.N)

14
app/src/main/java/eu/faircode/email/MessageHelper.java
View File

@ -1139,7 +1139,7 @@ public class MessageHelper {
if (header.trim().startsWith("=?"))
return header;
if (Helper.isUTF8(header)) {
if (CharsetHelper.isUTF8(header)) {
Log.w("Converting " + name + " to UTF-8");
return new String(header.getBytes(StandardCharsets.ISO_8859_1), StandardCharsets.UTF_8);
} else {
@ -1730,8 +1730,10 @@ public class MessageHelper {
warnings.add(context.getString(R.string.title_no_charset, charset));
if (part.isMimeType("text/plain")) {
if ((TextUtils.isEmpty(charset) || charset.equalsIgnoreCase(StandardCharsets.US_ASCII.name())) &&
Helper.isUTF8(result)) {
if (TextUtils.isEmpty(charset) && CharsetHelper.isISO2022JP(result))
result = new String(result.getBytes(StandardCharsets.ISO_8859_1), "ISO-2022-JP");
else if ((TextUtils.isEmpty(charset) || charset.equalsIgnoreCase(StandardCharsets.US_ASCII.name())) &&
CharsetHelper.isUTF8(result)) {
Log.i("Charset plain=UTF8");
result = new String(result.getBytes(StandardCharsets.ISO_8859_1), StandardCharsets.UTF_8);
}
@ -1740,7 +1742,9 @@ public class MessageHelper {
result = HtmlHelper.flow(result);
result = "<div x-plain=\"true\">" + HtmlHelper.formatPre(result) + "</div>";
} else if (part.isMimeType("text/html")) {
if (TextUtils.isEmpty(charset)) {
if (TextUtils.isEmpty(charset) && CharsetHelper.isISO2022JP(result))
result = new String(result.getBytes(StandardCharsets.ISO_8859_1), "ISO-2022-JP");
else if (TextUtils.isEmpty(charset)) {
// <meta charset="utf-8" />
// <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
String excerpt = result.substring(0, Math.min(MAX_META_EXCERPT, result.length()));
@ -1760,7 +1764,7 @@ public class MessageHelper {
try {
Log.i("Charset=" + meta);
Charset c = Charset.forName(charset);
if (c.equals(StandardCharsets.UTF_8) && !Helper.isUTF8(result))
if (c.equals(StandardCharsets.UTF_8) && !CharsetHelper.isUTF8(result))
break;
result = new String(result.getBytes(StandardCharsets.ISO_8859_1), charset);
break;