Bug#440217: exim4-config: lowuid router is misplaced in order and breaks common setups

[Andreas Metzler]

Package: exim4-config
Version: 4.67-8
Severity: important

Hello,
it is me again, finding brokenness rather late. :-(

I have recently taken a shot at using 250_exim4-config_lowuid hovever
it currently seems to be misplaced in the order of things since it is
called before evaluating /etc/aliases, which makes it impossible to
selectively redirect system-userws somewhere else:

m26s25:~# tail -n1 /etc/aliases
www-data: ametzler
m26s25:~# swaks --pipe "exim -bh 70.103.162.31" \
   -f ametzler at gmx.net -t www-data at m26s25.vlinux.de -q rcpt
[...]
** 550 no mail to system accounts

It is impossible to use exim4 -bt for testing the lowuid router since
it requires a remote address, but it stillshows where things go wrong:
m26s25:~# exim4 -bt www-data at m26s25.vlinux.de
R: lowuid_aliases for www-data at m26s25.vlinux.de (UID 33)
R: system_aliases for www-data at m26s25.vlinux.de
[...]

lowuid greps the id and rejects it, even before system_aliases sees
it.

This could easily be fixed by moving the router to a later point.

The current order causes another kind of breakage that is worse. The
router breaks our default /etc/aliases:
root: ametzler
abuse: root

m26s25:~# exim4 -bt abuse at m26s25.vlinux.de
R: system_aliases for abuse at m26s25.vlinux.de
R: lowuid_aliases for root at m26s25.vlinux.de (UID 0)
R: system_aliases for root at m26s25.vlinux.de
R: lowuid_aliases for ametzler at m26s25.vlinux.de (UID 1000)
R: system_aliases for ametzler at m26s25.vlinux.de
R: userforward for ametzler at m26s25.vlinux.de
R: procmail for ametzler at m26s25.vlinux.de
R: maildrop for ametzler at m26s25.vlinux.de
R: local_user for ametzler at m26s25.vlinux.de
ametzler at m26s25.vlinux.de
   <-- root at m26s25.vlinux.de
   <-- abuse at m26s25.vlinux.de
 outer = local_user, transport = maildir_home
m26s25:~# swaks --pipe "exim -bh 70.103.162.31" \
 -f ametzler at gmx.net -t abuse at m26s25.vlinux.de \
 -q rcpt 2>&1 | grep -E 'R: |550'
>>> R: dnslookup for ametzler at gmx.net
>>> R: system_aliases for abuse at m26s25.vlinux.de
>>> R: lowuid_aliases for root at m26s25.vlinux.de (UID 0)
<** 550 no mail to system accounts

No more time for debugging right now, I just wanted to file it.
cu andreas