> - gif does not pre-allocate a route (!)

	see in_gif_output().  it caches the route in sc->gif_ro.

	one problem is, it does not re-allocate route even if underlying
	routing table changes... latest kame code have some timer trick,
	but i'm not sure if it is the right way.

>   and arbitrarily limits recursion
>   with a single static counter. This seems to work effectively given the
>   non-reentrancy of this kernel path, and is XXX'd.

	another way to detect infinite loop is to use m->m_aux and have a
	list of interface it have gone through, but it seemed overkill to us.

itojun