upas/dkim: dkim signing for upas

This change adds support for dkim signing to upas.

It has2 pieces:

1. Adding support for different asn1 formats to auth/rsa2asn1;
   we can now generate SubjectPublicKeyInfo RSA keys, which
   wrap the keys up with an algorithm identifier.
2. Adding a upas/dkim command which filters a message and signs
   it using dkim.

To configure dkim, you need to generate a (small-ish) rsa key;
large keys do not fit into DNS text records:

	# generate the private key and add it to factotum
	ramfs -p
	cd /tmp
	auth/rsagen -b 2048 -t 'service=dkim role=sign hash=sha256 domain=orib.dev owner=*' > dkim.key
	cat dkim.key > factotum.ctl

	# extract the public key, encode it, and strip out the junk
	pubkey=`{
		<dkim.key auth/rsa2asn1 -f spki | \
		auth/pemencode WHATEVER | \
		grep -v 'WHATEVER' | \
		ssam 'x/\n/d'
	}
	domain=example.org
	# then add it to /lib/ndb.local
	echo 'dom=dkim._domainkey.'$domain' soa=
		ip=144.202.1.203
		refresh=600 ttl=600
		ns=ns.orib.dev
		txt="k=rsa; v='$pubkey \
	>> /lib/ndb/local

Then, finally, insert it into your outgoing mail pipeline. One
thing to be careful of is that upas will do some outgoing 'From:'
rewriting, so you may need to make sure that either '$upasname'
is set, or 'upas/dkim' is inserted after the rewrite stage.
A good place is in /mail/lib/qmail, in place of upas/vf:

	% cat /mail/lib/qmail
	rfork s
	upas/dkim -d example.com | upas/qer /mail/queue mail $* || exit 'qer failed'
	upas/runq -n 10 /mail/queue /mail/lib/remotemail </dev/null >/dev/null >[2=1] &

0 files changed, 0 insertions, 0 deletions