[libvirt] [PATCHv4 1/4] net-dhcp-leases: Implement the public APIs

[Daniel P. Berrange]

On Wed, Oct 02, 2013 at 09:13:59AM +0100, Daniel P. Berrange wrote:
> On Tue, Oct 01, 2013 at 05:39:02PM -0600, Eric Blake wrote:
> > On 09/26/2013 02:08 AM, Nehal J Wani wrote:
> > > Introduce 3 new APIs, virNetworkGetDHCPLeases, virNetworkGetDHCPLeasesForMAC
> > > and virNetworkDHCPLeaseFree.
> > > 
> > > * virNetworkGetDHCPLeases: returns the dhcp leases information for a given
> > >      virtual network.
> > > 
> > >      For DHCPv4, the information includes:
> > >      - Expirytime
> > >      - MAC Address
> > >      - IPv4 address (with type and prefix)
> > >      - Hostname (can be NULL)
> > >      - Client ID (can be NULL)
> > > 
> > >      For DHCPv6, the information includes
> > >      - Expirytime
> > >      - IAID
> > >      - IPv6 address (with type and prefix)
> > >      - Hostname (can be NULL)
> > >      - Client DUID
> > > 
> > > * virNetworkGetDHCPLeasesForMAC: returns the dhcp leases information for a
> > >      given virtual network and specified MAC Address.
> > > 
> > > * virNetworkDHCPLeaseFree: allows the upper layer application to free the
> > >      network interface object conveniently.
> > > 
> > > There is no support for flags, so user is expected to pass 0 for
> > > both the APIs.
> > 
> > 
> > > +typedef struct _virNetworkDHCPLeases virNetworkDHCPLeases;
> > > +typedef virNetworkDHCPLeases *virNetworkDHCPLeasesPtr;
> > > +struct _virNetworkDHCPLeases {
> > > +    long long expirytime;       /* Seconds since epoch */
> > > +    union {
> > > +        char *mac;              /* MAC address */
> > > +        unsigned long iaid;     /* Identity association identifier (IAID) */
> > > +    } id;
> > 
> > I'm not sure I like iaid - the whole point of this interface was to
> > return IP addresses associated with a MAC.  Either the iaid is important
> > and deserves a separate field, or all we care about is the MAC address.
> >  Not to mention that you didn't document which leg of the id union is
> > valid based on the type discriminator.
> 
> Agreed, we want the MAC address to be unconditionally available
> here. IMHO the IAID is not something we care about exposing. That
> is a impl detail of the DHCP comms protocol that is not useful
> to people outside.

Actually, I see that we already expose the IAID concept to the user
in the XML for networks

        <ip family="ipv6" address="2001:db8:ca2:2::1" prefix="64" >
          <dhcp>
            <host name="paul"   ip="2001:db8:ca2:2:3::1" />
            <host id="0:1:0:1:18:aa:62:fe:0:16:3e:44:55:66"    ip="2001:db8:ca2:2:3::2" />
            <host id="0:3:0:1:0:16:3e:11:22:33" name="ralph"  ip="2001:db8:ca2:2:3::3" />
            <host id="0:4:7e:7d:f0:7d:a8:bc:c5:d2:13:32:11:ed:16:ea:84:63" name="badbob" ip="2001:db8:ca2:2:3::4" />
          </dhcp>
        </ip>


The 'id' value is mapping to the IAID. So it is sensible to expose this
field in the virNetworkDHCPLease struct, but as a separate field, not
as a union.


Daniel
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