add panic if old code can be cleaned up

Signed-off-by: Kristoffer Dalby <[email protected]>

hscontrol/app.go

@@ -547,6 +547,8 @@ func nodesChangedHook(db *db.HSDatabase, polMan policy.PolicyManager, notif *not
 
 // Serve launches the HTTP and gRPC server service Headscale and the API.
 func (h *Headscale) Serve() error {
+	capver.CanOldCodeBeCleanedUp()
+
 	if profilingEnabled {
 		if profilingPath != "" {
 			err := os.MkdirAll(profilingPath, os.ModePerm)
@@ -566,7 +568,7 @@ func (h *Headscale) Serve() error {
 
 	log.Info().
 		Caller().
-		Str("minimum_version", capver.TailscaleVersion(MinimumCapVersion)).
+		Str("minimum_version", capver.TailscaleVersion(capver.MinSupportedCapabilityVersion)).
 		Msg("Clients with a lower minimum version will be rejected")
 
 	// Fetch an initial DERP Map before we start serving

hscontrol/capver/capver.go

@@ -9,6 +9,20 @@ import (
 	"tailscale.com/util/set"
 )
 
+const MinSupportedCapabilityVersion tailcfg.CapabilityVersion = 88
+
+// CanOldCodeBeCleanedUp is intended to be called on startup to see if
+// there are old code that can ble cleaned up, entries should contain
+// a CapVer where something can be cleaned up and a panic if it can.
+// This is only intended to catch things in tests.
+//
+// All uses of Capability version checks should be listed here.
+func CanOldCodeBeCleanedUp() {
+	if MinSupportedCapabilityVersion >= 111 {
+		panic("LegacyDERP can be cleaned up in tail.go")
+	}
+}
+
 func tailscaleVersSorted() []string {
 	vers := xmaps.Keys(tailscaleToCapVer)
 	sort.Strings(vers)

hscontrol/noise.go

@@ -150,12 +150,8 @@ func (ns *noiseServer) earlyNoise(protocolVersion int, writer io.Writer) error {
 	return nil
 }
 
-const (
-	MinSupportedCapabilityVersion tailcfg.CapabilityVersion = 88
-)
-
 func isSupportedVersion(version tailcfg.CapabilityVersion) bool {
-	return version >= MinimumCapVersion
+	return version >= capver.MinSupportedCapabilityVersion
 }
 
 func rejectUnsupported(
@@ -168,9 +164,9 @@ func rejectUnsupported(
 	if !isSupportedVersion(version) {
 		log.Error().
 			Caller().
-			Int("minimum_cap_ver", int(MinimumCapVersion)).
+			Int("minimum_cap_ver", int(capver.MinSupportedCapabilityVersion)).
 			Int("client_cap_ver", int(version)).
-			Str("minimum_version", capver.TailscaleVersion(MinimumCapVersion)).
+			Str("minimum_version", capver.TailscaleVersion(capver.MinSupportedCapabilityVersion)).
 			Str("client_version", capver.TailscaleVersion(version)).
 			Str("node_key", nkey.ShortString()).
 			Str("machine_key", mkey.ShortString()).