Dovecot Director Issue/Bug when host=""

[Julian De Marchi]

heya--

Been playing with dovecot today as I was learning about the features I
haven't used yet like the director/proxy stuff.

I setup a basic dovecot stack today which is 1 director and 1 IMAP
dovecot server behind it.

I have one user setup in MySQL and when I first changed from proxy mode
to director mode I left the host column populated with the IMAP server.
Once I confirmed this was working I then changed host to "" not NULL.

When I then preformed my next check I got these errors(no details
omitted as this is a test system):

Feb 20 14:57:19 smtp-test dovecot: auth-worker(15423): Debug:
sql(email3 at example.com,10.107.0.8): query: SELECT email as user,
password, host, 'Y' AS proxy_maybe, 'user' AS master, 'password' AS
pass, 'any-cert' AS 'ssl' FROM virtual_users WHERE
email='email3 at example.com';
Feb 20 14:57:19 smtp-test dovecot: auth: Error:
proxy(email3 at example.com,10.107.0.8,<Zz0b430PigAKawAI>): DNS lookup for
 failed: Invalid input from dns-client
Feb 20 14:57:19 smtp-test dovecot: auth: Error: close((null)) failed:
Bad file descriptor

When I changed the host data from "" to NULL all worked as expected.

So the question is: is this a bug with the error output? It was kind of
hard for me to diagnose at first without leaning on support in the
freenode channel.

This is very repeatable as it is a proper error, you can't resolve "".

--julian