The type `ns_pluginregister_ctx_t` was initially added to pass plugin
contextual data when the plugin is registered, but this is also now
passed into `plugin_check`. Furthermore, those various data are not
specific to the registration in particular. Rename the type into
`ns_pluginctx_t` for clarity.
The "origin" parameter for synthrecord is now mandatory for reverse
zones, but when configured in a non-reverse zone, it will default to
the zone name.
the plugin's operating mode is now determined automatically
from the zone name: if the name ends in "ip6.arpa" or "in-addr.arpa",
then the plugin is in reverse mode, otherwise forward.
Add a BIND9 plugin which, in "reverse" mode, enables the server to build
a synthesized response to a PTR query when the PTR record requested is
not found in the zone. (The plugin won't be called for names below a
delegation point, because it couldn't know whether a name actually
exists within the delegation.)
The dynamically-built name is constructed from a static prefix (passed
as a plugin parameter), the IP address (extracted from the query name)
and a suffx (also passed as a plugin parameter). An "allow-synth"
address-match list is used to limit the network addresses for which
the plugin may generate responses.
The plugin can also be used in "forward" mode, to build synthesized
A/AAAA records from names using the same format as he dynamically-built
PTR names, if the query name and type are not found in the zone.
The same parameters are used when the plugin is in forward mode:
the plugin will react and answer a query if the name matches the
configured prefix and origin, and encodes an IP address that is
within "allow-synth".
