// provisionNode allocates the IDs for one node, meant to be called from a tree
// traversal. If allocation fails, panic and expect to be recovered. The
// allocated IDs are stored in newIds so as to be collected in the recover
// routine.
func provisionNode(g canvas.Graph, this canvas.Node, newIds *[]canvas.NodeIfc) {
Info.Printf("Provisioning %s (%d)\n", this, this.ID())
for _, t := range g.From(this) {
e := g.E(this, t)
target := t.(canvas.Node)
chain := computeChainFrom(this, target)
fid, tid := e.F().Ifc(), e.T().Ifc()
var err error
if fid < 0 {
if fid, err = e.From().(canvas.Node).NewInterfaceID(); err != nil {
Error.Printf("Provisioning %s failed %s\n", e.From().(canvas.Node), err)
panic(err)
}
*newIds = append(*newIds, canvas.NodeIfc{e.From().ID(), fid})
}
if tid < 0 {
if tid, err = e.To().(canvas.Node).NewInterfaceID(); err != nil {
Error.Printf("Provisioning %s failed %s\n", e.To().(canvas.Node), err)
panic(err)
}
*newIds = append(*newIds, canvas.NodeIfc{e.To().ID(), tid})
}
if e.Update(chain, fid, tid) {
}
}
}
func computeChainFrom(from, to canvas.Node) (chain []canvas.NodeIfc) {
// For each link, there is a chain of modules to be invoked: the
// ingress policy modules, the egress policy modules, and the final
// forwarding nexthop.
//
// To compute the chain in each direction, the following algorithm is
// followed:
// Let T and F represent the set of groups for the 'to' and 'from'
// nodes, respectively.
// The leaving set L is the set difference between F and T.
// L := F - T
// The entering set E is the set difference between T and F
// E := T - F
//
// For the directed edge from:to, the chain is built as follows:
// For each module e in E, invoke the ingress policy (e.ifc[1])
// For each module l in L, invoke the egress policy (l.ifc[2])
//
// The directed edge to:from is calculated by calling this function
// with to/from reversed.
var e, l, x intsets.Sparse
l.Difference(from.Groups(), to.Groups())
e.Difference(to.Groups(), from.Groups())
var id int
x.Copy(&e)
for x.TakeMin(&id) {
chain = append(chain, canvas.NodeIfc{id, 1})
}
x.Copy(&l)
for x.TakeMin(&id) {
chain = append(chain, canvas.NodeIfc{id, 2})
}
return chain
}