Upcoming GMime 3.0 changes

[Jeffrey Stedfast <jestedfa microsoft com>]

Hello Balsa devs,

I'm sending this email to inform you guys of some upcoming GMime 3.0 features that I've either implemented or 
will be adding soon.

1. Probably the most import change coming to GMime 3.0 is that each header field/value pair has its own raw 
value cache instead of using a cached stream of the entire head block, thus forcing the complete invalidation 
of the header cache when anything changed in the headers. In GMime 2.6, once the header cache was 
invalidated, each header would get re-folded when written back out to disk. This was obviously not ideal.

2. Next up is the replacement of the old custom GnuPG back-end with GpgMe. Also included with this change is 
full support for S/MIME via both multipart/signed and application/pkcs7-mime content-types using gpgsm (via 
GpgMe). During this change, I also took the liberty of simplifying the crypto API's a bit and so I was able 
to make it such that g_mime_multipart_signed_verify(), for example, no longer requires you to pass it a 
GMimeCryptoContext. Instead, GMime parses the Content-Type's protocol parameter and uses that to instantiate 
the correct crypto context (GMimeGpgContext for PGP and GMimePkcs7Context for S/MIME). Many of the various 
state properties have been replaced with bitflags that can be passed to encrypt() and decrypt(). The sign() 
method now also takes a detach argument (might make this into a bitflag instead?) in order to support 
encapsulated signing.

3. The GMimeMessage API's have been improved a bit. Gone are the old GMimeMessage API's that return strings 
for the From and Reply-To headers. Instead, *all* GMimeMessage API's return an InternetAddressList pointer 
which can be used to manipulate the parsed address header. Also improved is the g_mime_message_set_subject() 
method which now takes an optional charset parameter (or NULL to use the default).

4. New in GMime 3.0 is the GMimeParserOptions struct which can be passed to GMimeParser and other parser 
functions exposed in the lower-level API's. This structure helps define how strict/forgiving the various 
parsing routines should be with the input. This replaces the need for g_mime_init()'s flags so you can change 
these settings on the fly now.

5. Another new feature is GMimeTextPart which makes getting/setting text on a GMimePart simpler. 
GMimeTextPart is a subclass of GMimePart, so all of the GMimePart API's that you are used to still work but 
now you also have access to convenient functions like g_mime_text_part_get_text() and 
g_mime_text_part_set_text() which removes the need for creating streams, data wrappers, and setting them on 
the part.

6. Brand new rfc822 address parser which is more tolerant than the previous generation parser. What's not to 
love?

7. And finally we get to a nifty feature that I just hacked up while waiting for some other code to compile 
(hey, it takes an hour to compile... I needed something to do!) which is that GMimeParser now scans for 
-----BEGIN PGP MESSAGE-----/-----END PGP MESSAGE----- and -----BEGIN PGP SIGNED MESSAGE-----/-----END PGP 
SIGNED MESSAGE----- markers while looking for MIME boundaries and sets some state on the corresponding 
GMimePart that you can use to quickly decide if the part contains encapsulated OpenPGP data.

Jeff