The `nat-local` and `nat-remote` keys contain information on the NAT
status of the local and remote IKE endpoints, respectively. If a
responder did not detect a NAT but is configured to fake a NAT situation
this is indicated by `nat-fake` (if an initiator fakes a NAT situation
`nat-local` is set). If any NAT is detected or faked `nat-any` is set.
Closesstrongswan/strongswan#16.
This is needed to handle DELETEs properly, which was previously done via
CHILD_REKEYING, which we don't use anymore since 5c6a62ceb6 as it prevents
reauthentication.
To simplify handling of authentication rounds in dictionaries/hashtables on the
client side, we assign unique names to each authentication round when listing
connection.
Handling the result for enum_from_name() is difficult, as checking for
negative return values requires a cast if the enum type is unsigned. The new
signature clearly differentiates lookup result from lookup value.
Further, this actually allows to convert real -1 enum values, which could not
be distinguished from "not-found" and the -1 return value.
This also fixes several clang warnings where enums are unsigned.