derp/derpserver: clean up extraction of derp.Server (#17264)

PR #17258 extracted `derp.Server` into `derp/derpserver.Server`.

This followup patch adds the following cleanups:
1. Rename `derp_server*.go` files to `derpserver*.go` to match
   the package name.
2. Rename the `derpserver.NewServer` constructor to `derpserver.New`
   to reduce stuttering.
3. Remove the unnecessary `derpserver.Conn` type alias.

Updates #17257
Updates #cleanup

Signed-off-by: Simon Law <sfllaw@tailscale.com>

cmd/derper/cert_test.go

@@ -131,7 +131,7 @@ func TestPinnedCertRawIP(t *testing.T) {
 	}
 	defer ln.Close()
 
-	ds := derpserver.NewServer(key.NewNode(), t.Logf)
+	ds := derpserver.New(key.NewNode(), t.Logf)
 
 	derpHandler := derpserver.Handler(ds)
 	mux := http.NewServeMux()

cmd/derper/derper.go

@@ -188,7 +188,7 @@ func main() {
 
 	serveTLS := tsweb.IsProd443(*addr) || *certMode == "manual"
 
-	s := derpserver.NewServer(cfg.PrivateKey, log.Printf)
+	s := derpserver.New(cfg.PrivateKey, log.Printf)
 	s.SetVerifyClient(*verifyClients)
 	s.SetTailscaledSocketPath(*socket)
 	s.SetVerifyClientURL(*verifyClientURL)

derp/derp_test.go

@@ -83,7 +83,7 @@ func TestClientInfoUnmarshal(t *testing.T) {
 
 func TestSendRecv(t *testing.T) {
 	serverPrivateKey := key.NewNode()
-	s := derpserver.NewServer(serverPrivateKey, t.Logf)
+	s := derpserver.New(serverPrivateKey, t.Logf)
 	defer s.Close()
 
 	const numClients = 3
@@ -305,7 +305,7 @@ func TestSendRecv(t *testing.T) {
 
 func TestSendFreeze(t *testing.T) {
 	serverPrivateKey := key.NewNode()
-	s := derpserver.NewServer(serverPrivateKey, t.Logf)
+	s := derpserver.New(serverPrivateKey, t.Logf)
 	defer s.Close()
 	s.WriteTimeout = 100 * time.Millisecond
 
@@ -549,7 +549,7 @@ const testMeshKey = "0123456789abcdef0123456789abcdef0123456789abcdef0123456789a
 func newTestServer(t *testing.T, ctx context.Context) *testServer {
 	t.Helper()
 	logf := logger.WithPrefix(t.Logf, "derp-server: ")
-	s := derpserver.NewServer(key.NewNode(), logf)
+	s := derpserver.New(key.NewNode(), logf)
 	s.SetMeshKey(testMeshKey)
 	ln, err := net.Listen("tcp", "127.0.0.1:0")
 	if err != nil {

derp/derphttp/derphttp_test.go

@@ -44,7 +44,7 @@ func TestSendRecv(t *testing.T) {
 		clientKeys = append(clientKeys, priv.Public())
 	}
 
-	s := derpserver.NewServer(serverPrivateKey, t.Logf)
+	s := derpserver.New(serverPrivateKey, t.Logf)
 	defer s.Close()
 
 	httpsrv := &http.Server{
@@ -172,7 +172,7 @@ func waitConnect(t testing.TB, c *derphttp.Client) {
 
 func TestPing(t *testing.T) {
 	serverPrivateKey := key.NewNode()
-	s := derpserver.NewServer(serverPrivateKey, t.Logf)
+	s := derpserver.New(serverPrivateKey, t.Logf)
 	defer s.Close()
 
 	httpsrv := &http.Server{
@@ -225,7 +225,7 @@ func TestPing(t *testing.T) {
 const testMeshKey = "0123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef"
 
 func newTestServer(t *testing.T, k key.NodePrivate) (serverURL string, s *derpserver.Server) {
-	s = derpserver.NewServer(k, t.Logf)
+	s = derpserver.New(k, t.Logf)
 	httpsrv := &http.Server{
 		TLSNextProto: make(map[string]func(*http.Server, *tls.Conn, http.Handler)),
 		Handler:      derpserver.Handler(s),

derp/derpserver/derpserver.go

@@ -57,8 +57,6 @@ import (
 	"tailscale.com/version"
 )
 
-type Conn = derp.Conn
-
 // verboseDropKeys is the set of destination public keys that should
 // verbosely log whenever DERP drops a packet.
 var verboseDropKeys = map[key.NodePublic]bool{}
@@ -181,7 +179,7 @@ type Server struct {
 
 	mu       sync.Mutex
 	closed   bool
-	netConns map[Conn]chan struct{} // chan is closed when conn closes
+	netConns map[derp.Conn]chan struct{} // chan is closed when conn closes
 	clients  map[key.NodePublic]*clientSet
 	watchers set.Set[*sclient] // mesh peers
 	// clientsMesh tracks all clients in the cluster, both locally
@@ -354,9 +352,9 @@ var bytesDropped = metrics.NewMultiLabelMap[dropReasonKindLabels](
 	"DERP bytes dropped by reason and by kind",
 )
 
-// NewServer returns a new DERP server. It doesn't listen on its own.
+// New returns a new DERP server. It doesn't listen on its own.
 // Connections are given to it via Server.Accept.
-func NewServer(privateKey key.NodePrivate, logf logger.Logf) *Server {
+func New(privateKey key.NodePrivate, logf logger.Logf) *Server {
 	var ms runtime.MemStats
 	runtime.ReadMemStats(&ms)
 
@@ -369,7 +367,7 @@ func NewServer(privateKey key.NodePrivate, logf logger.Logf) *Server {
 		packetsRecvByKind:   metrics.LabelMap{Label: "kind"},
 		clients:             map[key.NodePublic]*clientSet{},
 		clientsMesh:         map[key.NodePublic]PacketForwarder{},
-		netConns:            map[Conn]chan struct{}{},
+		netConns:            map[derp.Conn]chan struct{}{},
 		memSys0:             ms.Sys,
 		watchers:            set.Set[*sclient]{},
 		peerGoneWatchers:    map[key.NodePublic]set.HandleSet[func(key.NodePublic)]{},
@@ -570,7 +568,7 @@ func (s *Server) IsClientConnectedForTest(k key.NodePublic) bool {
 // on its own.
 //
 // Accept closes nc.
-func (s *Server) Accept(ctx context.Context, nc Conn, brw *bufio.ReadWriter, remoteAddr string) {
+func (s *Server) Accept(ctx context.Context, nc derp.Conn, brw *bufio.ReadWriter, remoteAddr string) {
 	closed := make(chan struct{})
 
 	s.mu.Lock()
@@ -910,7 +908,7 @@ func (s *Server) addWatcher(c *sclient) {
 	go c.requestMeshUpdate()
 }
 
-func (s *Server) accept(ctx context.Context, nc Conn, brw *bufio.ReadWriter, remoteAddr string, connNum int64) error {
+func (s *Server) accept(ctx context.Context, nc derp.Conn, brw *bufio.ReadWriter, remoteAddr string, connNum int64) error {
 	br := brw.Reader
 	nc.SetDeadline(time.Now().Add(10 * time.Second))
 	bw := &lazyBufioWriter{w: nc, lbw: brw.Writer}
@@ -1619,7 +1617,7 @@ type sclient struct {
 	// Static after construction.
 	connNum        int64 // process-wide unique counter, incremented each Accept
 	s              *Server
-	nc             Conn
+	nc             derp.Conn
 	key            key.NodePublic
 	info           derp.ClientInfo
 	logf           logger.Logf

derp/derpserver/derpserver_test.go

@@ -330,7 +330,7 @@ func TestMultiForwarder(t *testing.T) {
 func TestMetaCert(t *testing.T) {
 	priv := key.NewNode()
 	pub := priv.Public()
-	s := NewServer(priv, t.Logf)
+	s := New(priv, t.Logf)
 
 	certBytes := s.MetaCert()
 	cert, err := x509.ParseCertificate(certBytes)
@@ -368,7 +368,7 @@ func TestServerDupClients(t *testing.T) {
 
 	// run starts a new test case and resets clients back to their zero values.
 	run := func(name string, dupPolicy dupPolicy, f func(t *testing.T)) {
-		s = NewServer(serverPriv, t.Logf)
+		s = New(serverPriv, t.Logf)
 		s.dupPolicy = dupPolicy
 		c1 = &sclient{key: clientPub, logf: logger.WithPrefix(t.Logf, "c1: ")}
 		c2 = &sclient{key: clientPub, logf: logger.WithPrefix(t.Logf, "c2: ")}
@@ -618,7 +618,7 @@ func TestLimiter(t *testing.T) {
 // single Server instance with multiple concurrent client flows.
 func BenchmarkConcurrentStreams(b *testing.B) {
 	serverPrivateKey := key.NewNode()
-	s := NewServer(serverPrivateKey, logger.Discard)
+	s := New(serverPrivateKey, logger.Discard)
 	defer s.Close()
 
 	ln, err := net.Listen("tcp", "127.0.0.1:0")
@@ -688,7 +688,7 @@ func BenchmarkSendRecv(b *testing.B) {
 
 func benchmarkSendRecvSize(b *testing.B, packetSize int) {
 	serverPrivateKey := key.NewNode()
-	s := NewServer(serverPrivateKey, logger.Discard)
+	s := New(serverPrivateKey, logger.Discard)
 	defer s.Close()
 
 	k := key.NewNode()

prober/derp_test.go

@@ -146,7 +146,7 @@ func TestDerpProber(t *testing.T) {
 func TestRunDerpProbeNodePair(t *testing.T) {
 	// os.Setenv("DERP_DEBUG_LOGS", "true")
 	serverPrivateKey := key.NewNode()
-	s := derpserver.NewServer(serverPrivateKey, t.Logf)
+	s := derpserver.New(serverPrivateKey, t.Logf)
 	defer s.Close()
 
 	httpsrv := &http.Server{

tstest/integration/integration.go

@@ -296,7 +296,7 @@ func exe() string {
 func RunDERPAndSTUN(t testing.TB, logf logger.Logf, ipAddress string) (derpMap *tailcfg.DERPMap) {
 	t.Helper()
 
-	d := derpserver.NewServer(key.NewNode(), logf)
+	d := derpserver.New(key.NewNode(), logf)
 
 	ln, err := net.Listen("tcp", net.JoinHostPort(ipAddress, "0"))
 	if err != nil {

tstest/natlab/vnet/vnet.go

@@ -611,7 +611,7 @@ func newDERPServer() *derpServer {
 	ts.Close()
 
 	ds := &derpServer{
-		srv:       derpserver.NewServer(key.NewNode(), logger.Discard),
+		srv:       derpserver.New(key.NewNode(), logger.Discard),
 		tlsConfig: ts.TLS, // self-signed; test client configure to not check
 	}
 	var mux http.ServeMux

wgengine/magicsock/magicsock_test.go

@@ -111,7 +111,7 @@ func (c *Conn) WaitReady(t testing.TB) {
 }
 
 func runDERPAndStun(t *testing.T, logf logger.Logf, l nettype.PacketListener, stunIP netip.Addr) (derpMap *tailcfg.DERPMap, cleanup func()) {
-	d := derpserver.NewServer(key.NewNode(), logf)
+	d := derpserver.New(key.NewNode(), logf)
 
 	httpsrv := httptest.NewUnstartedServer(derpserver.Handler(d))
 	httpsrv.Config.ErrorLog = logger.StdLogger(logf)