The Annoyance Filter.pdf - Fourmilab

134 MAIL FOLDER ANNOYANCE-FILTER §159
159. Just because we’re interested in the contents of this part, doesn’t necessarily mean we can
comprehend it. First of all, it must be encoded in a form we can either read directly or have a decoder
for, and secondly it must be in a character set we understand, not some Asian chicken tracks. First of
all, test the character set and accept only those we read directly or have interpreters for.
〈 Test for multiple byte character sets and activate decoder if available 159 〉 ≡
bool gibberish = false ;
if (mimeContentTypeCharset .substr (0, 6) ≡ "gb2312") {
mbd euc.setMailFolder (this);
mbi gb2312 .setDecoder (mbd euc);
mbi = &mbi gb2312 ;
}
if (mimeContentTypeCharset ≡ "big5") {
mbd big5 .setMailFolder (this);
mbi big5 .setDecoder (mbd big5 );
mbi = &mbi big5 ;
}
if (mimeContentTypeCharset ≡ "utf−8") {
mbd utf 8 .setMailFolder (this);
mbi unicode .setDecoder (mbd utf 8 );
mbi = &mbi unicode ;
}
if (mimeContentTypeCharset ≡ "euc−kr") {
mbd euc.setMailFolder (this);
mbi kr .setDecoder (mbd euc);
mbi = &mbi kr ;
}
#ifdef CHECK_FOR_GIBBERISH_CHARACTER_SETS
if ((mimeContentTypeCharset .length ( ) ≡ 0) ∨ (mimeContentTypeCharset ≡
"us−ascii") ∨ (mimeContentTypeCharset .substr (0,
8) ≡ "iso−8859") ∨ (mimeContentTypeCharset ≡ "windows−1251")) {
if (Annotate (’d’)) {
ostringstream os ;
os ≪ "Accepting␣part␣in␣Content−Type−Charset:␣" ≪ mimeContentTypeCharset ≪
"␣␣(" ≪ mimeContentType ≪ "␣" ≪ mimeContentTransferEncoding ≪ ")";
reportParserDiagnostic(os );
}
}
else {
if (Annotate (’d’)) {
ostringstream os ;
}
#endif
os ≪ "Rejecting␣part␣in␣Content−Type−Charset:␣" ≪ mimeContentTypeCharset ≪
"␣␣(" ≪ mimeContentType ≪ "␣" ≪ mimeContentTransferEncoding ≪ ")";
reportParserDiagnostic(os );
}
gibberish = true ;
This code is used in section 158.