Does libpq have SSL functions?

I'd like to build some SSL functionality into my C functions that
access the PostgreSQL database. My C functions are calling the
routines from libpq. By chance, are there any SSL functions inherent
to libpq for establishing a secure connection to the postmaster?

I mention this because I noticed in the source code for psql, the c
file startup.c has the following line:

ssl = PQgetssl(pset.db);

I didn't seem to find any other SSL references in the /src/bin/psql
directory using grep, but I know that psql can be built with SSL
support so I was hoping to use the code for that as a template.

Thanks.
-Tony