IPSECKEY is kinda strange because it has a type selector which tells
what type a later rdata field has. The type can be a domainname, address
or v6 address. You sort of wish Go would have a union type for this, but
alas.
Currently this is implemented as:
GatewayA net.IP `dns:"a"`
GatewayAAAA net.IP `dns:"aaaa"`
GatewayName string `dns:"domain-name"`
In the IPSECKEY. Only one of these is active at any one time. When
parsing/packing and unpacking the value of GatewayType is checked
to see what to do.
Parsing from strings is also implemented properly and tested. The Unpack
function still needs work.
Some records are copies from others: DNSKEY, CDNSKEY and KEY are
identical. DS, CDS and DLV are too and even RRSIG and SIG.
The parsing functions and the definition can all be used for parsing
all these identical types.