wgengine/router: pull out interface method only needed in Linux

Instead of having userspace do the call into the router, just let the
router pick up the change itself.

Updates #15160

Signed-off-by: Claus Lensbøl <claus@tailscale.com>

wgengine/magicsock/magicsock.go

@@ -3464,7 +3464,9 @@ func (c *Conn) listenPacket(network string, port uint16) (nettype.PacketConn, er
 	return nettype.MakePacketListenerWithNetIP(netns.Listener(c.logf, c.netMon)).ListenPacket(ctx, network, addr)
 }
 
-// PortUpdate is an eventbus value, reporting the port and address family of a magicsock connection.
+// PortUpdate is an eventbus value, reporting the port and address family
+// magicsock is currently listening on, so it can be threaded through firewalls
+// and such.
 type PortUpdate struct {
 	UDPPort         uint16
 	EndpointNetwork string // either "udp4" or "udp6".

wgengine/router/callback.go

@@ -56,13 +56,6 @@ func (r *CallbackRouter) Set(rcfg *Config) error {
 	return r.SetBoth(r.rcfg, r.dcfg)
 }
 
-// UpdateMagicsockPort implements the Router interface. This implementation
-// does nothing and returns nil because this router does not currently need
-// to know what the magicsock UDP port is.
-func (r *CallbackRouter) UpdateMagicsockPort(_ uint16, _ string) error {
-	return nil
-}
-
 // SetDNS implements dns.OSConfigurator.
 func (r *CallbackRouter) SetDNS(dcfg dns.OSConfig) error {
 	r.mu.Lock()

wgengine/router/osrouter/router_linux.go

@@ -34,6 +34,7 @@ import (
 	"tailscale.com/util/eventbus"
 	"tailscale.com/util/linuxfw"
 	"tailscale.com/version/distro"
+	"tailscale.com/wgengine/magicsock"
 	"tailscale.com/wgengine/router"
 )
 
@@ -171,6 +172,7 @@ func newUserspaceRouterAdvanced(logf logger.Logf, tunname string, netMon *netmon
 // [eventbus.Client] is closed.
 func (r *linuxRouter) consumeEventbusTopics(ec *eventbus.Client) func(*eventbus.Client) {
 	ruleDeletedSub := eventbus.Subscribe[netmon.RuleDeleted](ec)
+	portUpdateSub := eventbus.Subscribe[magicsock.PortUpdate](ec)
 	return func(ec *eventbus.Client) {
 		for {
 			select {
@@ -178,6 +180,11 @@ func (r *linuxRouter) consumeEventbusTopics(ec *eventbus.Client) func(*eventbus.
 				return
 			case rs := <-ruleDeletedSub.Events():
 				r.onIPRuleDeleted(rs.Table, rs.Priority)
+			case pu := <-portUpdateSub.Events():
+				r.logf("portUpdate(port=%v, network=%s)", pu.UDPPort, pu.EndpointNetwork)
+				if err := r.updateMagicsockPort(pu.UDPPort, pu.EndpointNetwork); err != nil {
+					r.logf("updateMagicsockPort(port=%v, network=%s) failed: %v", pu.UDPPort, pu.EndpointNetwork, err)
+				}
 			}
 		}
 	}
@@ -540,8 +547,8 @@ func (r *linuxRouter) updateStatefulFilteringWithDockerWarning(cfg *router.Confi
 	r.health.SetHealthy(dockerStatefulFilteringWarnable)
 }
 
-// UpdateMagicsockPort implements the Router interface.
-func (r *linuxRouter) UpdateMagicsockPort(port uint16, network string) error {
+// updateMagicsockPort implements the Router interface.
+func (r *linuxRouter) updateMagicsockPort(port uint16, network string) error {
 	r.mu.Lock()
 	defer r.mu.Unlock()
 	if r.nfr == nil {

wgengine/router/osrouter/router_openbsd.go

@@ -238,13 +238,6 @@ func (r *openbsdRouter) Set(cfg *router.Config) error {
 	return errq
 }
 
-// UpdateMagicsockPort implements the Router interface. This implementation
-// does nothing and returns nil because this router does not currently need
-// to know what the magicsock UDP port is.
-func (r *openbsdRouter) UpdateMagicsockPort(_ uint16, _ string) error {
-	return nil
-}
-
 func (r *openbsdRouter) Close() error {
 	cleanUp(r.logf, r.tunname)
 	return nil

wgengine/router/osrouter/router_plan9.go

@@ -115,13 +115,6 @@ func (r *plan9Router) Set(cfg *router.Config) error {
 	return nil
 }
 
-// UpdateMagicsockPort implements the Router interface. This implementation
-// does nothing and returns nil because this router does not currently need
-// to know what the magicsock UDP port is.
-func (r *plan9Router) UpdateMagicsockPort(_ uint16, _ string) error {
-	return nil
-}
-
 func (r *plan9Router) Close() error {
 	// TODO(bradfitz): unbind
 	return nil

wgengine/router/osrouter/router_userspace_bsd.go

@@ -206,13 +206,6 @@ func (r *userspaceBSDRouter) Set(cfg *router.Config) (reterr error) {
 	return reterr
 }
 
-// UpdateMagicsockPort implements the Router interface. This implementation
-// does nothing and returns nil because this router does not currently need
-// to know what the magicsock UDP port is.
-func (r *userspaceBSDRouter) UpdateMagicsockPort(_ uint16, _ string) error {
-	return nil
-}
-
 func (r *userspaceBSDRouter) Close() error {
 	return nil
 }

wgengine/router/osrouter/router_windows.go

@@ -114,13 +114,6 @@ func hasDefaultRoute(routes []netip.Prefix) bool {
 	return false
 }
 
-// UpdateMagicsockPort implements the Router interface. This implementation
-// does nothing and returns nil because this router does not currently need
-// to know what the magicsock UDP port is.
-func (r *winRouter) UpdateMagicsockPort(_ uint16, _ string) error {
-	return nil
-}
-
 func (r *winRouter) Close() error {
 	r.firewall.clear()
 

wgengine/router/router.go

@@ -34,14 +34,6 @@ type Router interface {
 	// implementation should handle gracefully.
 	Set(*Config) error
 
-	// UpdateMagicsockPort tells the OS network stack what port magicsock
-	// is currently listening on, so it can be threaded through firewalls
-	// and such. This is distinct from Set() since magicsock may rebind
-	// ports independently from the Config changing.
-	//
-	// network should be either "udp4" or "udp6".
-	UpdateMagicsockPort(port uint16, network string) error
-
 	// Close closes the router.
 	Close() error
 }

wgengine/router/router_fake.go

@@ -27,11 +27,6 @@ func (r fakeRouter) Set(cfg *Config) error {
 	return nil
 }
 
-func (r fakeRouter) UpdateMagicsockPort(_ uint16, _ string) error {
-	r.logf("[v1] warning: fakeRouter.UpdateMagicsockPort: not implemented.")
-	return nil
-}
-
 func (r fakeRouter) Close() error {
 	r.logf("[v1] warning: fakeRouter.Close: not implemented.")
 	return nil

wgengine/userspace.go

@@ -549,7 +549,6 @@ func NewUserspaceEngine(logf logger.Logf, conf Config) (_ Engine, reterr error)
 // [eventbus.Client] is closed.
 func (e *userspaceEngine) consumeEventbusTopics(cli *eventbus.Client) func(*eventbus.Client) {
 	changeDeltaSub := eventbus.Subscribe[netmon.ChangeDelta](cli)
-	portUpdateSub := eventbus.Subscribe[magicsock.PortUpdate](cli)
 	return func(cli *eventbus.Client) {
 		for {
 			select {
@@ -560,11 +559,6 @@ func (e *userspaceEngine) consumeEventbusTopics(cli *eventbus.Client) func(*even
 					f()
 				}
 				e.linkChange(&changeDelta)
-			case pu := <-portUpdateSub.Events():
-				e.logf("portUpdate(port=%v, network=%s)", pu.UDPPort, pu.EndpointNetwork)
-				if err := e.router.UpdateMagicsockPort(pu.UDPPort, pu.EndpointNetwork); err != nil {
-					e.logf("UpdateMagicsockPort(port=%v, network=%s) failed: %v", pu.UDPPort, pu.EndpointNetwork, err)
-				}
 			}
 		}
 	}