cmd/tailscaled: move cleanup to an implicit action during startup

This removes a potentially increased boot delay for certain boot
topologies where they block on ExecStartPre that may have socket
activation dependencies on other system services (such as
systemd-resolved and NetworkManager).

Also rename cleanup to clean up in affected/immediately nearby places
per code review commentary.

Fixes #11599

Signed-off-by: James Tucker <james@tailscale.com>

wgengine/router/router.go

@@ -49,11 +49,11 @@ func New(logf logger.Logf, tundev tun.Device, netMon *netmon.Monitor) (Router, e
 	return newUserspaceRouter(logf, tundev, netMon)
 }
 
-// Cleanup restores the system network configuration to its original state
+// CleanUp restores the system network configuration to its original state
 // in case the Tailscale daemon terminated without closing the router.
 // No other state needs to be instantiated before this runs.
-func Cleanup(logf logger.Logf, interfaceName string) {
-	cleanup(logf, interfaceName)
+func CleanUp(logf logger.Logf, interfaceName string) {
+	cleanUp(logf, interfaceName)
 }
 
 // Config is the subset of Tailscale configuration that is relevant to

wgengine/router/router_darwin.go

@@ -13,6 +13,6 @@ func newUserspaceRouter(logf logger.Logf, tundev tun.Device, netMon *netmon.Moni
 	return newUserspaceBSDRouter(logf, tundev, netMon)
 }
 
-func cleanup(logger.Logf, string) {
+func cleanUp(logger.Logf, string) {
 	// Nothing to do.
 }

wgengine/router/router_default.go

@@ -18,6 +18,6 @@ func newUserspaceRouter(logf logger.Logf, tunDev tun.Device, netMon *netmon.Moni
 	return nil, fmt.Errorf("unsupported OS %q", runtime.GOOS)
 }
 
-func cleanup(logf logger.Logf, interfaceName string) {
+func cleanUp(logf logger.Logf, interfaceName string) {
 	// Nothing to do here.
 }

wgengine/router/router_freebsd.go

@@ -18,7 +18,7 @@ func newUserspaceRouter(logf logger.Logf, tundev tun.Device, netMon *netmon.Moni
 	return newUserspaceBSDRouter(logf, tundev, netMon)
 }
 
-func cleanup(logf logger.Logf, interfaceName string) {
+func cleanUp(logf logger.Logf, interfaceName string) {
 	// If the interface was left behind, ifconfig down will not remove it.
 	// In fact, this will leave a system in a tainted state where starting tailscaled
 	// will result in "interface tailscale0 already exists"

wgengine/router/router_linux.go

@@ -1396,12 +1396,12 @@ func normalizeCIDR(cidr netip.Prefix) string {
 	return cidr.Masked().String()
 }
 
-// cleanup removes all the rules and routes that were added by the linux router.
-// The function calls cleanup for both iptables and nftables since which ever
-// netfilter runner is used, the cleanup function for the other one doesn't do anything.
-func cleanup(logf logger.Logf, interfaceName string) {
+// cleanUp removes all the rules and routes that were added by the linux router.
+// The function calls cleanUp for both iptables and nftables since which ever
+// netfilter runner is used, the cleanUp function for the other one doesn't do anything.
+func cleanUp(logf logger.Logf, interfaceName string) {
 	if interfaceName != "userspace-networking" {
-		linuxfw.IPTablesCleanup(logf)
+		linuxfw.IPTablesCleanUp(logf)
 		linuxfw.NfTablesCleanUp(logf)
 	}
 }

wgengine/router/router_openbsd.go

@@ -236,11 +236,11 @@ func (r *openbsdRouter) UpdateMagicsockPort(_ uint16, _ string) error {
 }
 
 func (r *openbsdRouter) Close() error {
-	cleanup(r.logf, r.tunname)
+	cleanUp(r.logf, r.tunname)
 	return nil
 }
 
-func cleanup(logf logger.Logf, interfaceName string) {
+func cleanUp(logf logger.Logf, interfaceName string) {
 	out, err := cmd("ifconfig", interfaceName, "down").CombinedOutput()
 	if err != nil {
 		logf("ifconfig down: %v\n%s", err, out)

wgengine/router/router_windows.go

@@ -120,7 +120,7 @@ func (r *winRouter) Close() error {
 	return nil
 }
 
-func cleanup(logf logger.Logf, interfaceName string) {
+func cleanUp(logf logger.Logf, interfaceName string) {
 	// Nothing to do here.
 }