IRRd 4.0.3

IRRd 4.0.3 was released on June 29th, 2019, and contains
one change relating to referential integrity validation
between RPSL objects.

In earlier versions of IRRd, the members attribute of
an as-set, along with several others,
were strongly validated[1]. This meant it was not possible
to add or update an as-set, if some of the members were
not valid objects in the same source. The same applied
to fields like member-of in a route-set.

In IRRd 4.0.3, all references from members, mp-member,
mbrs-by-ref and member-of are weak references. Their
syntax is validated, e.g. for as-set members, values must
be a valid as-set name or a valid AS number. However, there
is no validation on whether the objects actually exist.
It is also possible to delete e.g. a route-set, even when
the object is still listed in the member-of in a route
object, or to reference a maintainer that does not exist
in a mbrs-by-ref.

[1] #240