[exim-dev] Support for SSL compression

Hi,

Since May 2004, an RFC (3749) exists, that finally assigned a code (1)
to the deflate compression method for usage with TLS. Already SSL 3.0
introduced compression negotiation in the "SSL Hello" commands.

GnuTLS current version supports deflate by default. OpenSSL does also
support SSL deflate compression, but you have to register it.

So, with rather minor changes, we could make both API versions "compression
aware".

What I wonder is if anybody has thought about that / discussed it.

In tls-gnu.c, deflate-compression is more or less actively excluded (by
only specifying the "NUL" compression). Is there a reason for this?
The length of the compression priority list suggests Nikos Mavroyanopoulos
originally intended to make this configurable.

If nobody has concerns, I'd like to write an Exim path to enable
compression. It would be a nice "marketing" feature for an upcoming
release.

Kind regards,


Georg v.Zezschwitz