Re: OpenDKIM and Postfix milter protocol version

On Mon, 22 Aug 2011, Steve Jenkins wrote:
> Does it depend on the version of libmilter that is installed? How can
> I check to see which version of libmilter is on any given system, or
> which OpenDKIM was built against?

"opendkim -V" (capital "V") gives you that information, such as:

         SMFI_VERSION 0x1000001
         libmilter version 1.0.1

The SMFI_VERSION constant comes from the include file mfapi.h and is used
to figure out which version of the include file you have. The other value
comes from the library itself and tells you what version of the library
you had at compile time. They should match up, and recent versions of
libmilter will refuse to start if they don't.

There's also a constant in mfdef.h called SMFI_PROT_VERSION which matches
the version number of the protocol itself, i.e., the language actually
spoken between an MTA and a milter. This is where it gets interesting as
an MTA and a milter might know different protocol versions and still, in
most cases, be able to interact.

I can't remember the exact details of what protocol features were added in
each version. I think the postfix version chart is probably the closest
thing to a good summary there is. For the most part opendkim can operate
just fine with any of them, but it's not RFC-compliant without at least
version 2 which allows header field insertion (where the earliest versions
allowed only appending).

-MSK
Received on Wed Aug 24 2011 - 07:00:29 PST