net/dns/resolver: remove the Config struct.

In preparation for reintroducing a runtime reconfig Config struct.

Signed-off-by: David Anderson <danderson@tailscale.com>

net/dns/resolver/tsdns.go

@@ -82,34 +82,18 @@ type Resolver struct {
 	dnsMap *Map
 }
 
-// Config is the set of configuration options for a Resolver.
+// New returns a new resolver.
-type Config struct {
+// linkMon optionally specifies a link monitor to use for socket rebinding.
-	// Logf is the logger to use throughout the Resolver.
+func New(logf logger.Logf, linkMon *monitor.Mon) *Resolver {
-	Logf logger.Logf
-	// Forward determines whether the resolver will forward packets to
-	// nameservers set with SetUpstreams if the domain name is not of a Tailscale node.
-	Forward bool
-	// LinkMonitor optionally provides a link monitor to use to rebind
-	// connections on link changes.
-	// If nil, rebinds are not performend.
-	LinkMonitor *monitor.Mon
-}
-
-// New constructs a resolver associated with the given root domain.
-// The root domain must be in canonical form (with a trailing period).
-func New(config Config) *Resolver {
 	r := &Resolver{
-		logf:      logger.WithPrefix(config.Logf, "dns: "),
+		logf:      logger.WithPrefix(logf, "dns: "),
-		linkMon:   config.LinkMonitor,
+		linkMon:   linkMon,
 		queue:     make(chan Packet, queueSize),
 		responses: make(chan Packet),
 		errors:    make(chan error),
 		closed:    make(chan struct{}),
 	}
-
+	r.forwarder = newForwarder(r.logf, r.responses)
-	if config.Forward {
-		r.forwarder = newForwarder(r.logf, r.responses)
-	}
 	if r.linkMon != nil {
 		r.unregLinkMon = r.linkMon.RegisterChangeCallback(r.onLinkMonitorChange)
 	}
@@ -145,10 +129,7 @@ func (r *Resolver) Close() {
 		r.unregLinkMon()
 	}
 
-	if r.forwarder != nil {
+	r.forwarder.Close()
-		r.forwarder.Close()
-	}
-
 	r.wg.Wait()
 }
 
@@ -156,9 +137,7 @@ func (r *Resolver) onLinkMonitorChange(changed bool, state *interfaces.State) {
 	if !changed {
 		return
 	}
-	if r.forwarder != nil {
+	r.forwarder.rebindFromNetworkChange()
-		r.forwarder.rebindFromNetworkChange()
-	}
 }
 
 // SetMap sets the resolver's DNS map, taking ownership of it.
@@ -173,9 +152,7 @@ func (r *Resolver) SetMap(m *Map) {
 // SetUpstreams sets the addresses of the resolver's
 // upstream nameservers, taking ownership of the argument.
 func (r *Resolver) SetUpstreams(upstreams []net.Addr) {
-	if r.forwarder != nil {
+	r.forwarder.setUpstreams(upstreams)
-		r.forwarder.setUpstreams(upstreams)
-	}
 	r.logf("set upstreams: %v", upstreams)
 }
 
@@ -307,14 +284,10 @@ func (r *Resolver) poll() {
 		out, err := r.respond(packet.Payload)
 
 		if err == errNotOurName {
-			if r.forwarder != nil {
+			err = r.forwarder.forward(packet)
-				err = r.forwarder.forward(packet)
+			if err == nil {
-				if err == nil {
+				// forward will send response into r.responses, nothing to do.
-					// forward will send response into r.responses, nothing to do.
+				continue
-					continue
-				}
-			} else {
-				err = errNotForwarding
 			}
 		}
 

net/dns/resolver/tsdns_test.go

@@ -194,7 +194,7 @@ func TestRDNSNameToIPv6(t *testing.T) {
 }
 
 func TestResolve(t *testing.T) {
-	r := New(Config{Logf: t.Logf, Forward: false})
+	r := New(t.Logf, nil)
 	r.SetMap(dnsMap)
 
 	if err := r.Start(); err != nil {
@@ -240,7 +240,7 @@ func TestResolve(t *testing.T) {
 }
 
 func TestResolveReverse(t *testing.T) {
-	r := New(Config{Logf: t.Logf, Forward: false})
+	r := New(t.Logf, nil)
 	r.SetMap(dnsMap)
 
 	if err := r.Start(); err != nil {
@@ -318,7 +318,7 @@ func TestDelegate(t *testing.T) {
 		return
 	}
 
-	r := New(Config{Logf: t.Logf, Forward: true})
+	r := New(t.Logf, nil)
 	r.SetMap(dnsMap)
 	r.SetUpstreams([]net.Addr{
 		v4server.PacketConn.LocalAddr(),
@@ -397,7 +397,7 @@ func TestDelegateCollision(t *testing.T) {
 	}
 	defer server.Shutdown()
 
-	r := New(Config{Logf: t.Logf, Forward: true})
+	r := New(t.Logf, nil)
 	r.SetMap(dnsMap)
 	r.SetUpstreams([]net.Addr{server.PacketConn.LocalAddr()})
 
@@ -463,7 +463,7 @@ func TestDelegateCollision(t *testing.T) {
 }
 
 func TestConcurrentSetMap(t *testing.T) {
-	r := New(Config{Logf: t.Logf, Forward: false})
+	r := New(t.Logf, nil)
 
 	if err := r.Start(); err != nil {
 		t.Fatalf("start: %v", err)
@@ -499,7 +499,7 @@ func TestConcurrentSetUpstreams(t *testing.T) {
 	}
 	defer server.Shutdown()
 
-	r := New(Config{Logf: t.Logf, Forward: true})
+	r := New(t.Logf, nil)
 	r.SetMap(dnsMap)
 
 	if err := r.Start(); err != nil {
@@ -670,7 +670,7 @@ var emptyResponse = []byte{
 }
 
 func TestFull(t *testing.T) {
-	r := New(Config{Logf: t.Logf, Forward: false})
+	r := New(t.Logf, nil)
 	r.SetMap(dnsMap)
 
 	if err := r.Start(); err != nil {
@@ -709,7 +709,7 @@ func TestFull(t *testing.T) {
 }
 
 func TestAllocs(t *testing.T) {
-	r := New(Config{Logf: t.Logf, Forward: false})
+	r := New(t.Logf, nil)
 	r.SetMap(dnsMap)
 
 	if err := r.Start(); err != nil {
@@ -778,7 +778,7 @@ func BenchmarkFull(b *testing.B) {
 	}
 	defer server.Shutdown()
 
-	r := New(Config{Logf: b.Logf, Forward: true})
+	r := New(b.Logf, nil)
 	r.SetMap(dnsMap)
 	r.SetUpstreams([]net.Addr{server.PacketConn.LocalAddr()})
 

wgengine/userspace.go

@@ -219,11 +219,7 @@ func NewUserspaceEngine(logf logger.Logf, conf Config) (_ Engine, reterr error)
 		e.linkMonOwned = true
 	}
 
-	e.resolver = resolver.New(resolver.Config{
+	e.resolver = resolver.New(logf, e.linkMon)
-		Logf:        logf,
-		Forward:     true,
-		LinkMonitor: e.linkMon,
-	})
 
 	logf("link state: %+v", e.linkMon.InterfaceState())