[libvirt] Need to re-work final "peer address" patches and re-push them

[Laine Stump]

I reverted these three patches that introduced and enabled a "peer" 
attribute for type='ethernet' interface <ip> elements prior to the 
release of 1.3.4 with the intent of fixing/re-posting them after 
release, but forgot until today:

https://www.redhat.com/archives/libvir-list/2016-April/msg01995.html

I have patches for most of the bugs, but the one problem that still 
doesn't have resolution is the naming of the "peer" attribute. In my 
opinion, having the two address attributes named "address" and "peer" 
makes it ambiguous which address is for the guest side and which for the 
host side (especially since the attribute that has been named "peer" 
would be set to the "address" in the netlink command, and the attribute 
named "address" would be set to "peer" in the netlink command :-O).

Since "address" is an existing attribute, and already used for the guest 
side IP address in lxc type='bridge' interfaces, it must remain as-is. 
In order to make it obvious that the new address is for the host side of 
the tap (or veth pair in the case of lxc), I propose calling it either 
"host", or "hostAddress", e.g:

      <ip address='192.168.123.43' host='192.168.123.1' prefix='25'/>

or

      <ip address='192.168.123.4' hostAddress='192.168.123.1' prefix='25'/>

(Vasiliy had suggested "hostPeer", but I dislike that, since it sounds 
like "the peer of the host", which is even more misleading).

Can some of you normally-opinionated people weigh in on this? I don't 
like the feeling of making a unilateral decision :-)

Also, I'm realizing that, although there was a patch to support setting 
the host-side address (hmm - "hostSide"? nah) for lxc type='bridge' 
interface, this is not at all useful, because anything plugged into a 
bridge should not have any IP on the side plugged into the bridge. The 
place where it would be useful for lxc would be (just as it is for qemu) 
with a type='ethernet' interface - the guest-side veth would have 
"address" and the host-side veth would have "hostAddress", and it would 
then properly work without needing a bridge (which I think is the entire 
point). Since lxc doesn't currently support type='ethernet', I think 
that initial support should be made for qemu only, and when 
type='ethernet is added to lxc, it can be made to support an IP address 
on both sides of the veth pair from the start.

Lacking any useful responses, I'm thinking to update Vasiliy's patches 
to use "hostAddress" (and fix the other bugs I had found) and re-post them.