The Annoyance Filter.pdf - Fourmilab

130 MAIL FOLDER ANNOYANCE-FILTER §150
150. A multi-part message in MIME format will contain a declaration in the header which identifies
the body as being in that format and provides a part separator sentinel which appears before each
subsequent part. We test for the MIME declaration and save the part boundary sentinel for later use.
〈 Process multipart MIME header declaration 150 〉 ≡
string ::size type p, p1 ;
string arg ;
if (inHeader ∧ compareHeaderField (s, "content−type", arg )) {
string sc = s;
}
stringCanonicalise (sc);
if ((p = sc.find ("multipart/", 13)) ≠ string ::npos ) {
if ((p = sc.find ("boundary=", p + 10)) ≠ string ::npos ) {
if (s[p + 9] ≡ ’\"’) {
p1 = sc.find ("\"", p + 10);
p += 10;
}
else {
p += 9;
p1 = sc.length ( ) − p;
}
multiPart = true ;
partBoundary = s.substr (p, (p1 − p));
if (Annotate (’d’)) {
ostringstream os ;
}
}
}
os ≪ "Multi−part␣boundary:␣\"" ≪ partBoundary ≪ "\"";
reportParserDiagnostic(os );
This code is cited in section 256.
This code is used in section 141.
151. If we’re in the body of a MIME multi-part message, we must test each line against the
partBoundary sentinel declared in the “Content−type:” header statement. If the line is a part boundary,
we then must parse the part header which follows.
〈 Check for MIME part sentinel 151 〉 ≡
if (multiPart ∧ (¬inHeader ) ∧ (partBoundary ≠ "") ∧ (s.substr (0, 2) ≡ "−−") ∧ (s.substr (2,
partBoundary .length ( )) ≡ partBoundary ) ∧ (s.substr (partBoundary .length ( ) + 2) ≠ "−−")) {
inPartHeader = true ;
mimeContentType = mimeContentTypeCharset = mimeContentTypeBoundary =
mimeContentTransferEncoding = "";
}
This code is used in section 130.