libpq - check PGconn* - is it valid

Hi everyone.

I have such a problem. My application, some server, use libpq librarry
to interact with PostgreSQL-8.1.0 database. Postgresql server and my
server work on different computers in the local network. When my server
starts, it creates pool of 10 connections to database. My server use
PQexec() to submit queries to db. But when there is no network
connection to the database (I simply unplug the network cable from
computer on which PG server is run) and my server calls PQexec() -
than it hangs in PQexec() call. And it will hang there for a very
long time (I wait about 30 minutes and there is no result). And
when I plug in the network cable back, PQexec() remains hanging (I
wait about 10 minutes and there is no result too).

I use simply (not ssl) connection to db.

So how can I check PGconn pointer if it represent a health connection
to prevent my server to hang in PQexec() call?

Thanks in advance.
-- 
Best regards,Dmitriy Chumack                         mailto:saint@apriorit.com
Software Developer of ApriorIT