mesh: init ed25519-signed gossip layer; conflict-resolving route store

Signed-off-by: NotAShelf <raf@notashelf.dev>
Change-Id: I92ff256da8e84e86cd9e7c2b511c0ae56a6a6964

internal/mesh/mesh_test.go

@@ -0,0 +1,75 @@
+package mesh_test
+
+import (
+	"testing"
+	"time"
+
+	"notashelf.dev/ncro/internal/cache"
+	"notashelf.dev/ncro/internal/mesh"
+)
+
+func TestSignVerify(t *testing.T) {
+	node, err := mesh.NewNode("", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	msg := mesh.Message{
+		Type:      mesh.MsgAnnounce,
+		NodeID:    node.ID(),
+		Timestamp: time.Now().UnixNano(),
+		Routes:    []cache.RouteEntry{{StorePath: "abc123", UpstreamURL: "https://cache.nixos.org"}},
+	}
+
+	data, sig, err := node.Sign(msg)
+	if err != nil {
+		t.Fatalf("Sign: %v", err)
+	}
+	if err := mesh.Verify(node.PublicKey(), data, sig); err != nil {
+		t.Errorf("Verify: %v", err)
+	}
+}
+
+func TestVerifyFailsOnTamper(t *testing.T) {
+	node, _ := mesh.NewNode("", nil)
+	msg := mesh.Message{Type: mesh.MsgAnnounce, NodeID: node.ID()}
+	data, sig, _ := node.Sign(msg)
+	data[0] ^= 0xFF
+	if err := mesh.Verify(node.PublicKey(), data, sig); err == nil {
+		t.Error("expected verification failure on tampered data")
+	}
+}
+
+func TestMergeLowerLatencyWins(t *testing.T) {
+	store := mesh.NewRouteStore()
+	store.Merge([]cache.RouteEntry{
+		{StorePath: "pkg-a", UpstreamURL: "https://slow.example.com", LatencyEMA: 200, TTL: time.Now().Add(time.Hour)},
+	})
+	store.Merge([]cache.RouteEntry{
+		{StorePath: "pkg-a", UpstreamURL: "https://fast.example.com", LatencyEMA: 10, TTL: time.Now().Add(time.Hour)},
+	})
+
+	entry := store.Get("pkg-a")
+	if entry == nil {
+		t.Fatal("entry is nil")
+	}
+	if entry.UpstreamURL != "https://fast.example.com" {
+		t.Errorf("expected fast upstream, got %q", entry.UpstreamURL)
+	}
+}
+
+func TestMergeNewerTimestampWinsOnTie(t *testing.T) {
+	store := mesh.NewRouteStore()
+	now := time.Now()
+	store.Merge([]cache.RouteEntry{
+		{StorePath: "pkg-b", UpstreamURL: "https://a.example.com", LatencyEMA: 50, LastVerified: now.Add(-time.Minute), TTL: time.Now().Add(time.Hour)},
+	})
+	store.Merge([]cache.RouteEntry{
+		{StorePath: "pkg-b", UpstreamURL: "https://b.example.com", LatencyEMA: 50, LastVerified: now, TTL: time.Now().Add(time.Hour)},
+	})
+
+	entry := store.Get("pkg-b")
+	if entry.UpstreamURL != "https://b.example.com" {
+		t.Errorf("expected newer upstream, got %q", entry.UpstreamURL)
+	}
+}