calculating the MD5 hash of role passwords in C

Hello,

If I look into the database I see:

sisis71=# select rolname, rolpassword from pg_authid where rolname = 'sisis';
 rolname |             rolpassword
---------+-------------------------------------
 sisis   | md52f128a1fbbecc4b16462e8fc8dda5cd5

I know the clear text password of the role, it is simple 'sisis123', how
could I calculate the above MD5 hash from the clear text password, for
example in C? Which salt is used for the crypt(3) function?

Thanks

    matthias
--
Matthias Apitz, ✉ guru@unixarea.de, http://www.unixarea.de/ +49-176-38902045
Public GnuPG key: http://www.unixarea.de/key.pub