Exim still accepting emails to nonexistent users

[Heiko Schlittermann]

Hi,

Heiko Schlittermann <hs at schlittermann.de> (Mo 21 Nov 2016 11:50:13 CET):
> a) Routing stage
> You need to interact with the user database dovecot uses.
> Either you access the user database directory (flat file, LDAP,
> whatever) or you use the ${readsocket…} feature of Exim to talk to
> dovecot.

The readsocket trick doesn't seem to work anymore.

Using 
    $ socat STDIO UNIX:/run/dovecot/auth-master 
 <  VERSION 1   1
 <  SPID    16290
 >  VERSION 1   1
 >  USER    42  hs12 service=imap
 <  USER    1   hs12    uid=500 gid=500 home=/var/vmail/home/h/hs12

(the spaces are tabs).

But using Exim

    exim -be '${readsocket{/run/dovecot/auth-userdb}{VERSION\t1\t1\nUSER\t1\hs12\tservice=imap\n}}'

does not work. Exim closes the sending side right after the final \n
with shutdown(2). Dovecot seems to see this as if the connection should
be closed now and closes the connection, w/o any response.

As it's not unusual to shutdown(2) the sender if the message is sent,
I'd see this as a bug on the dovecot side. There is no reason to
consider the connection as dead, just because the sender closed
its sending side of the connection.

    Best regards from Dresden/Germany
    Viele Grüße aus Dresden
    Heiko Schlittermann
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