This avoids having to register certificates with authority/ca backends
beforehand, which is tricky for intermediate CA certificates loaded
themselves via authority/ca sections. On the other hand, the form of
these URLs can't be determined by config backends anymore (not an issue
for the two current implementations, no idea if custom implementations
ever made use of that possibility). If that became necessary, we could
perhaps pass the certificate to the CDP enumerator or add a new method
to the credential_set_t interface.
If the key type was specified but the ID was NULL or matched a subject, it
was possible that a certificate was returned that didn't actually match
the requested key type.
Closesstrongswan/strongswan#141.
Since 11c14bd2f5 CA certificates referenced in ca sections were
enumerated by two credential sets if they were also stored in
ipsec.d/cacerts. This caused duplicate certificate requests to
get sent. All CA certificates, whether loaded automatically or
via a ca section, are now stored in stroke_ca_t.
Certificates referenced in ca sections are now also reloaded
when `ipsec rereadcacerts` is used.
This makes these CA certificates independent from the purge issued by reread
commands. Certificates loaded by CA sections can be removed through ipsec.conf
update/reread, while CA certificates loaded implicitly from ipsec.d/cacerts
can individually be reread using ipsec rereadcacerts.