opendkim 2.11.0~alpha-11build1 / usr / share / doc / opendkim / examples / final.lua.sample

--
--  Copyright (c) 2009, 2010, 2012, The Trusted Domain Project.
--    All rights reserved.
--
--  final.lua.sample -- sample version of the "final" script that demonstrates
--                      all of the features of the configuration file
--
--  The final script is executed after the entire message body has been
--  received and processed but before the filter renders its final verdict.
--  The main use of this script is to determine whether or not the message
--  is acceptable to the verifier, and what final filtering action should be
--  taken.  For exmaple, if the message failed Author Domain Signing
--  Practises tests, or had additional data appended to it beyond what the
--  signature covered, or even if the signature simply failed to verify,
--  this script can detect such things and take whatever action is desired.

--  Retrieve signature count
nsigs = odkim.get_sigcount(ctx)
if nsigs == nil then
	return nil
end

--  Enact ADSP.
--  1) If it reported NXDOMAIN, reject.
if odkim.get_presult(ctx) == DKIM_PRESULT_NXDOMAIN then
	odkim.set_reply(ctx, "554", "5.7.1", "sender domain does not exist")
	odkim.set_result(ctx, SMFIS_REJECT)
	return nil
end

--  2) Test for discardable.  We'll handle "unknown" and "all" through RFC5451.
if odkim.get_presult(ctx) == DKIM_PRESULT_FOUND and
   odkim.get_policy(ctx) == DKIM_POLICY_DISCARDABLE then
	discard = true
	for n = 1, nsigs
		sig = odkim.get_sighandle(ctx, n)
		sigres = odkim.sig_result(sig)
		sdomain = odkim.sig_getdomain(sig)
		if sigres == 0 and sdomain == fromdomain then
			discard = false
		end
	end
	if discard then
		odkim.set_result(ctx, SMFIS_REJECT)
		return nil
	end
end

--  If the message had too much stuff added to it (more than 120 bytes)
--  then bounce it
for n = 1, nsigs do
	sig = odkim.get_sighandle(ctx, n)
	bodylen = odkim.sig_bodylength(sig)
	canonlen = odkim.sig_canonlength(sig)
	if bodylen > canonlen + 120 then
		odkim.set_reply(ctx, "554", "",
		                "Too much data after DKIM-protected body")
		odkim.set_result(ctx, SMFIS_REJECT)
	end
end

--  That's it!
return nil