Report the networks the outward links are on, for the local network (issue 154, ADR 0340)

A port reached from local-network is admitted from the private networks the machine is attached to, and only the machine can say which those are. Every network on a link facing outside is said among its facts, and a change is said at the next reconcile.

cmd/mesh-host/local_network_test.go

@@ -0,0 +1,29 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/novox/mesh-host/internal/link"
+	"github.com/novox/mesh-host/internal/outward"
+	"github.com/novox/mesh-host/internal/profile"
+)
+
+func reportOn(networks ...outward.Network) link.Report {
+	return link.Report{Outward: []string{"eth0"},
+		Profile: profileAsReported(profile.Profile{Machine: &profile.Machine{Networks: networks}})}
+}
+
+// **A change of the networks a machine is attached to is said unasked** (novox/hq ADR 0340 §7): a port
+// reached from the local network is admitted from them, so a laptop that joins another network is said at
+// the next reconcile, not at the next push — and the same networks again are not news.
+func TestAChangedNetworkIsSaidUnasked(t *testing.T) {
+	w := &adoptionWatch{}
+	home := reportOn(outward.Network{Link: "eth0", Network: "192.168.1.0/24"})
+	w.said(home)
+	if w.differs(reportOn(outward.Network{Link: "eth0", Network: "192.168.1.0/24"})) {
+		t.Fatal("the same networks read as a change, so the machine would speak on every reconcile")
+	}
+	if !w.differs(reportOn(outward.Network{Link: "eth0", Network: "10.20.0.0/16"})) {
+		t.Fatal("a machine that moved to another network does not say so until it is pushed to")
+	}
+}

cmd/mesh-host/main.go

@@ -1397,6 +1397,12 @@ func adoptionFingerprint(r link.Report) string {
 	// it could only speak when a declaration arrived, and a declaration cannot be composed until it
 	// has spoken: a machine waiting for a push that is waiting for the machine.
 	parts := []string{"firewall=" + r.Firewall, "outward=" + strings.Join(r.Outward, ",")}
+	// **And the networks those links are on** (novox/hq ADR 0340 §7): a port reached from the local
+	// network is admitted from them, so a laptop that joins another network, or a lease that moves, is
+	// said at the next reconcile rather than at the next push or the next day.
+	if networks := attachedNetworksOf(r); networks != "" {
+		parts = append(parts, "networks="+networks)
+	}
 	for _, h := range r.Held {
 		parts = append(parts, "held "+h.ID+"="+h.Changed)
 	}
@@ -1428,6 +1434,26 @@ func adoptionFingerprint(r link.Report) string {
 	return strings.Join(parts, "\n")
 }
 
+// attachedNetworksOf is the networks a report's profile says the machine is attached to, as one line: the
+// part of what the machine is made of that the filter is composed from (novox/hq ADR 0340).
+func attachedNetworksOf(r link.Report) string {
+	machine, ok := r.Profile["machine"].(map[string]any)
+	if !ok {
+		return ""
+	}
+	networks, ok := machine["networks"].([]any)
+	if !ok {
+		return ""
+	}
+	said := make([]string, 0, len(networks))
+	for _, n := range networks {
+		if entry, ok := n.(map[string]any); ok {
+			said = append(said, fmt.Sprintf("%v %v", entry["link"], entry["network"]))
+		}
+	}
+	return strings.Join(said, ",")
+}
+
 // applyState is how an apply went, as the fingerprint keeps it: refused, clean, or failed with what it did not
 // apply and which keys its failure is said under.
 func applyState(r link.Report) string {