Admit a port from the machine's own local network, and never a public subnet (issue 154, ADR 0340)

A local service could only be declared public, which says the internet. local-network is a source and a reach: the private network and the private networks the machine reported on a link facing outside, judged here, shown by plan and node, and said in the rule set when there are none.

cmd/mesh-controller/local_network.go

@@ -0,0 +1,67 @@
+package main
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/novox/mesh-controller/internal/catalogue"
+	"github.com/novox/mesh-controller/internal/inventory"
+	"github.com/novox/mesh-controller/internal/overlay"
+)
+
+// localNetworksOf is a machine's attached networks judged (novox/hq ADR 0340): which count as its local
+// network, from what it last said of itself and the links it said face outside it. A machine that has
+// said none judges to nothing, and a port reached from `local-network` is then admitted from the private
+// network only, and said so.
+func localNetworksOf(ctx context.Context, inv *inventory.Inventory, node string) ([]catalogue.LocalNetwork, error) {
+	account, had, err := inv.MachineOf(ctx, node)
+	if err != nil {
+		return nil, err
+	}
+	outward, err := inv.OutwardLinksOf(ctx, node)
+	if err != nil {
+		return nil, err
+	}
+	return judgedNetworks(account, had, outward, overlay.Interface), nil
+}
+
+// judgedNetworks is the judging alone, from what was read.
+func judgedNetworks(account inventory.MachineAccount, had bool, outward []string, tunnel string) []catalogue.LocalNetwork {
+	if !had || account.Machine == nil {
+		return nil
+	}
+	attached := make([]catalogue.AttachedNetwork, 0, len(account.Machine.Networks))
+	for _, n := range account.Machine.Networks {
+		attached = append(attached, catalogue.AttachedNetwork{Link: n.Link, Network: n.Network})
+	}
+	return catalogue.JudgeLocalNetworks(attached, outward, tunnel)
+}
+
+// localNetworkLines is what `node` shows of a machine's attached networks (ADR 0340 §8): each one, with
+// whether it counts as the local network and why, or why none is shown.
+func localNetworkLines(account inventory.MachineAccount, had bool, judged []catalogue.LocalNetwork) []string {
+	out := []string{"  its local network (what a port reached from local-network is admitted from):"}
+	switch {
+	case !had || account.Machine == nil:
+		return append(out, "    not said — this machine has not reported what it is attached to")
+	case len(account.Machine.Networks) == 0:
+		why := account.Machine.Unknown["networks"]
+		if why == "" {
+			why = "its node-engine is older than the one that says it"
+		}
+		return append(out, "    not said — "+why)
+	}
+	counted := 0
+	for _, j := range judged {
+		verdict := "not counted"
+		if j.Counts {
+			verdict = "counts"
+			counted++
+		}
+		out = append(out, fmt.Sprintf("    %-22s on %-10s %s: %s", j.Network, j.Link, verdict, j.Why))
+	}
+	if counted == 0 {
+		out = append(out, "    none counts: a port reached from local-network is admitted from the private network only")
+	}
+	return out
+}