control/controlclient: start fetching the server noise key

Updates #3488

Signed-off-by: Maisem Ali <maisem@tailscale.com>

control/controlclient/direct.go

@@ -47,6 +47,7 @@ import (
 	"tailscale.com/types/opt"
 	"tailscale.com/types/persist"
 	"tailscale.com/util/clientmetric"
+	"tailscale.com/util/multierr"
 	"tailscale.com/util/systemd"
 	"tailscale.com/wgengine/monitor"
 )
@@ -69,7 +70,9 @@ type Direct struct {
 	pinger                 Pinger
 
 	mu             sync.Mutex        // mutex guards the following fields
-	serverKey    key.MachinePublic
+	serverKey      key.MachinePublic // original ("legacy") nacl crypto_box-based public key
+	serverNoiseKey key.MachinePublic
+
 	persist      persist.Persist
 	authKey      string
 	tryingNewKey key.NodePrivate
@@ -326,16 +329,17 @@ func (c *Direct) doLogin(ctx context.Context, opt loginOpt) (mustRegen bool, new
 
 	c.logf("doLogin(regen=%v, hasUrl=%v)", regen, opt.URL != "")
 	if serverKey.IsZero() {
-		var err error
-		serverKey, err = loadServerKey(ctx, c.httpc, c.serverURL)
+		keys, err := loadServerPubKeys(ctx, c.httpc, c.serverURL)
 		if err != nil {
 			return regen, opt.URL, err
 		}
 		c.logf("control server key %s from %s", serverKey.ShortString(), c.serverURL)
 
 		c.mu.Lock()
-		c.serverKey = serverKey
+		c.serverKey = keys.LegacyPublicKey
+		c.serverNoiseKey = keys.PublicKey
 		c.mu.Unlock()
+		serverKey = keys.LegacyPublicKey
 	}
 
 	var oldNodeKey key.NodePublic
@@ -950,29 +954,39 @@ func encode(v interface{}, serverKey key.MachinePublic, mkey key.MachinePrivate)
 	return mkey.SealTo(serverKey, b), nil
 }
 
-func loadServerKey(ctx context.Context, httpc *http.Client, serverURL string) (key.MachinePublic, error) {
-	req, err := http.NewRequest("GET", serverURL+"/key", nil)
+func loadServerPubKeys(ctx context.Context, httpc *http.Client, serverURL string) (*tailcfg.OverTLSPublicKeyResponse, error) {
+	keyURL := fmt.Sprintf("%v/key?v=%d", serverURL, tailcfg.CurrentCapabilityVersion)
+	req, err := http.NewRequestWithContext(ctx, "GET", keyURL, nil)
 	if err != nil {
-		return key.MachinePublic{}, fmt.Errorf("create control key request: %v", err)
+		return nil, fmt.Errorf("create control key request: %v", err)
 	}
-	req = req.WithContext(ctx)
 	res, err := httpc.Do(req)
 	if err != nil {
-		return key.MachinePublic{}, fmt.Errorf("fetch control key: %v", err)
+		return nil, fmt.Errorf("fetch control key: %v", err)
 	}
 	defer res.Body.Close()
-	b, err := ioutil.ReadAll(io.LimitReader(res.Body, 1<<16))
+	b, err := ioutil.ReadAll(io.LimitReader(res.Body, 64<<10))
 	if err != nil {
-		return key.MachinePublic{}, fmt.Errorf("fetch control key response: %v", err)
+		return nil, fmt.Errorf("fetch control key response: %v", err)
 	}
 	if res.StatusCode != 200 {
-		return key.MachinePublic{}, fmt.Errorf("fetch control key: %d: %s", res.StatusCode, string(b))
+		return nil, fmt.Errorf("fetch control key: %d", res.StatusCode)
 	}
+	var out tailcfg.OverTLSPublicKeyResponse
+	jsonErr := json.Unmarshal(b, &out)
+	if jsonErr == nil {
+		return &out, nil
+	}
+
+	// Some old control servers might not be updated to send the new format.
+	// Accept the old pre-JSON format too.
+	out = tailcfg.OverTLSPublicKeyResponse{}
 	k, err := key.ParseMachinePublicUntyped(mem.B(b))
 	if err != nil {
-		return key.MachinePublic{}, fmt.Errorf("fetch control key: %v", err)
+		return nil, multierr.New(jsonErr, err)
 	}
-	return k, nil
+	out.LegacyPublicKey = k
+	return &out, nil
 }
 
 // Debug contains temporary internal-only debug knobs.

tstest/integration/testcontrol/testcontrol.go

@@ -58,6 +58,10 @@ type Server struct {
 	cond       *sync.Cond // lazily initialized by condLocked
 	pubKey     key.MachinePublic
 	privKey    key.ControlPrivate // not strictly needed vs. MachinePrivate, but handy to test type interactions.
+
+	noisePubKey  key.MachinePublic
+	noisePrivKey key.ControlPrivate // not strictly needed vs. MachinePrivate, but handy to test type interactions.
+
 	nodes         map[key.NodePublic]*tailcfg.Node
 	users         map[key.NodePublic]*tailcfg.User
 	logins        map[key.NodePublic]*tailcfg.Login
@@ -211,30 +215,42 @@ func (s *Server) serveUnhandled(w http.ResponseWriter, r *http.Request) {
 	go panic(fmt.Sprintf("testcontrol.Server received unhandled request: %s", got.Bytes()))
 }
 
-func (s *Server) publicKey() key.MachinePublic {
-	pub, _ := s.keyPair()
-	return pub
+func (s *Server) publicKeys() (noiseKey, pubKey key.MachinePublic) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	s.ensureKeyPairLocked()
+	return s.noisePubKey, s.pubKey
 }
 
 func (s *Server) privateKey() key.ControlPrivate {
-	_, priv := s.keyPair()
-	return priv
-}
-
-func (s *Server) keyPair() (pub key.MachinePublic, priv key.ControlPrivate) {
 	s.mu.Lock()
 	defer s.mu.Unlock()
-	if s.pubKey.IsZero() {
+	s.ensureKeyPairLocked()
+	return s.privKey
+}
+
+func (s *Server) ensureKeyPairLocked() {
+	if !s.pubKey.IsZero() {
+		return
+	}
+	s.noisePrivKey = key.NewControl()
+	s.noisePubKey = s.noisePrivKey.Public()
 	s.privKey = key.NewControl()
 	s.pubKey = s.privKey.Public()
 }
-	return s.pubKey, s.privKey
-}
 
 func (s *Server) serveKey(w http.ResponseWriter, r *http.Request) {
+	noiseKey, legacyKey := s.publicKeys()
+	if r.FormValue("v") == "" {
 		w.Header().Set("Content-Type", "text/plain")
-	w.WriteHeader(200)
-	io.WriteString(w, s.publicKey().UntypedHexString())
+		io.WriteString(w, legacyKey.UntypedHexString())
+		return
+	}
+	w.Header().Set("Content-Type", "application/json")
+	json.NewEncoder(w).Encode(&tailcfg.OverTLSPublicKeyResponse{
+		LegacyPublicKey: legacyKey,
+		PublicKey:       noiseKey,
+	})
 }
 
 func (s *Server) serveMachine(w http.ResponseWriter, r *http.Request) {
@@ -245,6 +261,7 @@ func (s *Server) serveMachine(w http.ResponseWriter, r *http.Request) {
 		mkeyStr = mkeyStr[:i]
 	}
 
+	// TODO(maisem/bradfitz): support noise protocol here.
 	mkey, err := key.ParseMachinePublicUntyped(mem.S(mkeyStr))
 	if err != nil {
 		http.Error(w, "bad machine key hex", 400)