[Swan-dev] ip_range

[Antony Antony]

On Sun, Oct 13, 2019 at 01:18:29PM -0400, Andrew Cagney wrote:
> PS:
> 
> Moving the size logic out of ttorange() and into a function vis:

agree. Though I want to recored is_subet (with /) or a range (with 
- ) inside the ttorange. That is important for jam_range.
 
> bool range_size(const ip_range *range, uintmax_t *staturated_size)
> MUST_USE_RESULT /* false if overflow */
> 
> (same for converse range+offset) I think does have merit. 

I have the similar idea. If the offset is variable lease the address could 
begin closer to the prefix boundry.


> On Sun, 13 Oct 2019 at 12:49, Andrew Cagney <andrew.cagney at gmail.com> wrote:
> >
> > 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:

in ikev2 traffic selectors it is a transient use. I tempted to leave 
ip_range the same for now. Your next argument is more convincing. See 
bellow.

> > /*
> >  * 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.

no. I don't think so. Libreswan and linux kernel currenly only accept a 
subnet. I herd a Kernel developer, Stefeen, mumbling add kernel support for 
range because in RFC IP and port are ranges. 

> > >
> > > 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.

Yes.

However, there is convience factor in accepting smaller prefixes say /64, 
even upto /32 and for testing purposes /1; even though size is truncated to 
to 2^32-1.

> > > 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.
> > >

sure. sounds good to me. I don't have a preference. I guess I will move the 
.size to ip_pool and size computation a funcation as Andrew suggest.

> > > Among other things, this would allow improved modularization and
> > > better diagnostics.

-antony