[Swan-dev] ip_range

[Andrew Cagney]

On Sun, 13 Oct 2019 at 11:04, D. Hugh Redelmeier <hugh at mimosa.com> wrote:
>
> The ip_range type seems to be used for two purposes:
>
> - traffic selectors

The (ikev2) traffic selector code outputs an ip_subnet, not an
ip_range  Internally it just happens to use an ip_range as part of the
journey towards a subnet.  Like the comment points out:

/*
 * This is not the subnet you're looking for.
 *
 * In libreswan ip_subnet is used to store client routing information.
 * IKEv2 calls this traffic selectors and it allows the negotiation
 * of:
 *
 *    LO_ADDRESS..HI_ADDRESS : LO_PORT..HI_PORT
 *
 * The structures below can only handle a limited subset of this,
 * namely:
 *
 *    NETWORK_PREFIX | 0 / MASK : PORT
 *
 * where PORT==0 imples 0..65535, and (presumably) port can only be
 * non-zero when the NETWORK_PREFIX/MASK is for a single address.
 */



> - ip address pools
>
> The two uses have diverged.  Lots of complexity has been added for the
> address pool case which is not clearly correct or useful for the traffic
> selector case.
>
> Is there an RFC-based limit on range sizes for traffic selectors?
> If so, that should be enforced (i.e. violation should be failure,
> not truncation).  If not, we should not trunctate them.
>
> For address pools, I think that we get to set the rules.  It seems to
> me that 2^32 is large enough.  That's what our code supports.  Why not
> treat a larger size as an actual error rather than truncating to
> specified range?  Then a lot of truncation logic goes away.  Clearly
> this limit must be spelled out in the documentation (perhaps it is --
> I haven't looked).

This is what Antony did.

> The routines that currently do truncation don't know whether they are
> dealing with a traffic selector or an address pool.
>
> I suggest that the old ip_range type be reinstated and that a new type,
> perhaps "pool_range", be added with the new features.
>
> The pool_range type could be composed of an ip_range and some additions.
>
> Among other things, this would allow improved modularization and
> better diagnostics.
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