[Exim] readsocket and ending input

I have an application where I need to make a call to a unix domain socket and
utilize the data returned in a condition, etc..

${readsocket{/tmp/FilterLookup}{GET ${local_part}@${domain}\n}{20s}{\n}}

This appears to work fine, I see the request come into my "server" and the
response should be generated properly (I checked), however exim waits until
20s is up then reports a timeout.

I'm thinking that exim is expecting something to tell it that the server is
done sending data..

My return data is multiline, this may have something to do with things..

Anyone have any suggestions?