types: lead AllowedIPs with the node's own addresses

As SaaS. tailscale whois prints AllowedIPs[2:] as routes, so sorted
entries showed an own address in place of a subnet route.

hscontrol/mapper/tail_test.go

@@ -137,8 +137,8 @@ func TestTailNode(t *testing.T) {
 				),
 				Addresses: []netip.Prefix{netip.MustParsePrefix("100.64.0.1/32")},
 				AllowedIPs: []netip.Prefix{
-					tsaddr.AllIPv4(),
 					netip.MustParsePrefix("100.64.0.1/32"),
+					tsaddr.AllIPv4(),
 					netip.MustParsePrefix("192.168.0.0/24"),
 					tsaddr.AllIPv6(),
 				},
@@ -399,11 +399,9 @@ func TestTailNodeDisableIPv4(t *testing.T) {
 			name:     "cap_keeps_advertised_subnet_route",
 			hasCap:   true,
 			approved: []netip.Prefix{subnet},
-			// AllowedIPs is sorted by netip.Prefix.Compare so IPv4
-			// sorts before IPv6.
 			wantAllowed: []netip.Prefix{
-				subnet,
 				netip.MustParsePrefix("fd7a:115c:a1e0::1/128"),
+				subnet,
 			},
 			wantPrimary: []netip.Prefix{subnet},
 			wantAddrs:   []netip.Prefix{netip.MustParsePrefix("fd7a:115c:a1e0::1/128")},

hscontrol/servertest/via_compat_test.go

@@ -601,9 +601,11 @@ func selfRoutes(nm *netmap.NetworkMap) string {
 
 	var allowed, primary []string
 
-	for _, pfx := range self.AllowedIPs().All() {
+	for i, pfx := range self.AllowedIPs().All() {
 		if !views.SliceContains(self.Addresses(), pfx) {
 			allowed = append(allowed, pfx.String())
+		} else if i >= self.Addresses().Len() {
+			allowed = append(allowed, "own address after a route: "+pfx.String())
 		}
 	}
 
@@ -828,6 +830,10 @@ func comparePeers(
 			prefix := peer.AllowedIPs().At(i)
 			if isTailscaleIP(prefix) {
 				tsIPs = append(tsIPs, prefix)
+
+				// As SaaS: own addresses lead, and whois reads routes by position.
+				assert.Lessf(check["peer-addresses"], i, peer.Addresses().Len(),
+					"peer %s: own address %s comes after a route", name, prefix)
 			} else {
 				routePrefixes = append(routePrefixes, prefix.String())
 			}

hscontrol/types/node.go

@@ -1411,8 +1411,10 @@ func (nv NodeView) TailNode(
 
 	// routeFunc returns ALL routes (subnet + exit) for this node.
 	allRoutes := primaryRouteFunc(nv.ID())
-	allowedIPs := slices.Concat(addresses, allRoutes)
-	slices.SortFunc(allowedIPs, netip.Prefix.Compare)
+
+	// Own addresses lead, as on SaaS: `tailscale whois` prints AllowedIPs[2:]
+	// as the peer's routes.
+	allowedIPs := slices.Concat(addresses, slices.SortedFunc(slices.Values(allRoutes), netip.Prefix.Compare))
 
 	// PrimaryRoutes only includes non-exit subnet routes for HA tracking.
 	var primaryRoutes []netip.Prefix