Improvements on Noise implementation (#1379)

CHANGELOG.md

@@ -7,12 +7,13 @@
 - Add environment flags to enable pprof (profiling) [#1382](https://github.com/juanfont/headscale/pull/1382)
   - Profiles are continously generated in our integration tests.
 - Fix systemd service file location in `.deb` packages [#1391](https://github.com/juanfont/headscale/pull/1391)
+- Improvements on Noise implementation [#1379](https://github.com/juanfont/headscale/pull/1379)
 
 ## 0.22.1 (2023-04-20)
 
 ### Changes
 
-- Fix issue where SystemD could not bind to port 80 [#1365](https://github.com/juanfont/headscale/pull/1365)
+- Fix issue where systemd could not bind to port 80 [#1365](https://github.com/juanfont/headscale/pull/1365)
 
 ## 0.22.0 (2023-04-20)
 

noise.go

@@ -1,6 +1,9 @@
 package headscale
 
 import (
+	"encoding/binary"
+	"encoding/json"
+	"io"
 	"net/http"
 
 	"github.com/gorilla/mux"
@@ -9,18 +12,37 @@ import (
 	"golang.org/x/net/http2/h2c"
 	"tailscale.com/control/controlbase"
 	"tailscale.com/control/controlhttp"
-	"tailscale.com/net/netutil"
+	"tailscale.com/tailcfg"
+	"tailscale.com/types/key"
 )
 
 const (
 	// ts2021UpgradePath is the path that the server listens on for the WebSockets upgrade.
 	ts2021UpgradePath = "/ts2021"
+
+	// The first 9 bytes from the server to client over Noise are either an HTTP/2
+	// settings frame (a normal HTTP/2 setup) or, as Tailscale added later, an "early payload"
+	// header that's also 9 bytes long: 5 bytes (earlyPayloadMagic) followed by 4 bytes
+	// of length. Then that many bytes of JSON-encoded tailcfg.EarlyNoise.
+	// The early payload is optional. Some servers may not send it... But we do!
+	earlyPayloadMagic = "\xff\xff\xffTS"
+
+	// EarlyNoise was added in protocol version 49.
+	earlyNoiseCapabilityVersion = 49
 )
 
-type ts2021App struct {
+type noiseServer struct {
 	headscale *Headscale
 
+	httpBaseConfig *http.Server
+	http2Server    *http2.Server
 	conn           *controlbase.Conn
+	machineKey     key.MachinePublic
+	nodeKey        key.NodePublic
+
+	// EarlyNoise-related stuff
+	challenge       key.ChallengePrivate
+	protocolVersion int
 }
 
 // NoiseUpgradeHandler is to upgrade the connection and hijack the net.Conn
@@ -44,7 +66,18 @@ func (h *Headscale) NoiseUpgradeHandler(
 		return
 	}
 
-	noiseConn, err := controlhttp.AcceptHTTP(req.Context(), writer, req, *h.noisePrivateKey, nil)
+	noiseServer := noiseServer{
+		headscale: h,
+		challenge: key.NewChallenge(),
+	}
+
+	noiseConn, err := controlhttp.AcceptHTTP(
+		req.Context(),
+		writer,
+		req,
+		*h.noisePrivateKey,
+		noiseServer.earlyNoise,
+	)
 	if err != nil {
 		log.Error().Err(err).Msg("noise upgrade failed")
 		http.Error(writer, err.Error(), http.StatusInternalServerError)
@@ -52,10 +85,9 @@ func (h *Headscale) NoiseUpgradeHandler(
 		return
 	}
 
-	ts2021App := ts2021App{
+	noiseServer.conn = noiseConn
-		headscale: h,
+	noiseServer.machineKey = noiseServer.conn.Peer()
-		conn:      noiseConn,
+	noiseServer.protocolVersion = noiseServer.conn.ProtocolVersion()
-	}
 
 	// This router is served only over the Noise connection, and exposes only the new API.
 	//
@@ -63,16 +95,70 @@ func (h *Headscale) NoiseUpgradeHandler(
 	// a single hijacked connection from /ts2021, using netutil.NewOneConnListener
 	router := mux.NewRouter()
 
-	router.HandleFunc("/machine/register", ts2021App.NoiseRegistrationHandler).
+	router.HandleFunc("/machine/register", noiseServer.NoiseRegistrationHandler).
 		Methods(http.MethodPost)
-	router.HandleFunc("/machine/map", ts2021App.NoisePollNetMapHandler)
+	router.HandleFunc("/machine/map", noiseServer.NoisePollNetMapHandler)
 
 	server := http.Server{
 		ReadTimeout: HTTPReadTimeout,
 	}
-	server.Handler = h2c.NewHandler(router, &http2.Server{})
+
-	err = server.Serve(netutil.NewOneConnListener(noiseConn, nil))
+	noiseServer.httpBaseConfig = &http.Server{
+		Handler:           router,
+		ReadHeaderTimeout: HTTPReadTimeout,
+	}
+	noiseServer.http2Server = &http2.Server{}
+
+	server.Handler = h2c.NewHandler(router, noiseServer.http2Server)
+
+	noiseServer.http2Server.ServeConn(
+		noiseConn,
+		&http2.ServeConnOpts{
+			BaseConfig: noiseServer.httpBaseConfig,
+		},
+	)
+}
+
+func (ns *noiseServer) earlyNoise(protocolVersion int, writer io.Writer) error {
+	log.Trace().
+		Caller().
+		Int("protocol_version", protocolVersion).
+		Str("challenge", ns.challenge.Public().String()).
+		Msg("earlyNoise called")
+
+	if protocolVersion < earlyNoiseCapabilityVersion {
+		log.Trace().
+			Caller().
+			Msgf("protocol version %d does not support early noise", protocolVersion)
+
+		return nil
+	}
+
+	earlyJSON, err := json.Marshal(&tailcfg.EarlyNoise{
+		NodeKeyChallenge: ns.challenge.Public(),
+	})
 	if err != nil {
-		log.Info().Err(err).Msg("The HTTP2 server was closed")
+		return err
 	}
+
+	// 5 bytes that won't be mistaken for an HTTP/2 frame:
+	// https://httpwg.org/specs/rfc7540.html#rfc.section.4.1 (Especially not
+	// an HTTP/2 settings frame, which isn't of type 'T')
+	var notH2Frame [5]byte
+	copy(notH2Frame[:], earlyPayloadMagic)
+	var lenBuf [4]byte
+	binary.BigEndian.PutUint32(lenBuf[:], uint32(len(earlyJSON)))
+	// These writes are all buffered by caller, so fine to do them
+	// separately:
+	if _, err := writer.Write(notH2Frame[:]); err != nil {
+		return err
+	}
+	if _, err := writer.Write(lenBuf[:]); err != nil {
+		return err
+	}
+	if _, err := writer.Write(earlyJSON); err != nil {
+		return err
+	}
+
+	return nil
 }

protocol_noise.go

@@ -10,7 +10,7 @@ import (
 )
 
 // // NoiseRegistrationHandler handles the actual registration process of a machine.
-func (t *ts2021App) NoiseRegistrationHandler(
+func (ns *noiseServer) NoiseRegistrationHandler(
 	writer http.ResponseWriter,
 	req *http.Request,
 ) {
@@ -20,6 +20,11 @@ func (t *ts2021App) NoiseRegistrationHandler(
 
 		return
 	}
+
+	log.Trace().
+		Any("headers", req.Header).
+		Msg("Headers")
+
 	body, _ := io.ReadAll(req.Body)
 	registerRequest := tailcfg.RegisterRequest{}
 	if err := json.Unmarshal(body, &registerRequest); err != nil {
@@ -33,5 +38,7 @@ func (t *ts2021App) NoiseRegistrationHandler(
 		return
 	}
 
-	t.headscale.handleRegisterCommon(writer, req, registerRequest, t.conn.Peer(), true)
+	ns.nodeKey = registerRequest.NodeKey
+
+	ns.headscale.handleRegisterCommon(writer, req, registerRequest, ns.conn.Peer(), true)
 }

protocol_noise_poll.go

@@ -21,13 +21,18 @@ import (
 // only after their first request (marked with the ReadOnly field).
 //
 // At this moment the updates are sent in a quite horrendous way, but they kinda work.
-func (t *ts2021App) NoisePollNetMapHandler(
+func (ns *noiseServer) NoisePollNetMapHandler(
 	writer http.ResponseWriter,
 	req *http.Request,
 ) {
 	log.Trace().
 		Str("handler", "NoisePollNetMap").
 		Msg("PollNetMapHandler called")
+
+	log.Trace().
+		Any("headers", req.Header).
+		Msg("Headers")
+
 	body, _ := io.ReadAll(req.Body)
 
 	mapRequest := tailcfg.MapRequest{}
@@ -41,7 +46,9 @@ func (t *ts2021App) NoisePollNetMapHandler(
 		return
 	}
 
-	machine, err := t.headscale.GetMachineByAnyKey(t.conn.Peer(), mapRequest.NodeKey, key.NodePublic{})
+	ns.nodeKey = mapRequest.NodeKey
+
+	machine, err := ns.headscale.GetMachineByAnyKey(ns.conn.Peer(), mapRequest.NodeKey, key.NodePublic{})
 	if err != nil {
 		if errors.Is(err, gorm.ErrRecordNotFound) {
 			log.Warn().
@@ -63,5 +70,5 @@ func (t *ts2021App) NoisePollNetMapHandler(
 		Str("machine", machine.Hostname).
 		Msg("A machine is entering polling via the Noise protocol")
 
-	t.headscale.handlePollCommon(writer, req.Context(), machine, mapRequest, true)
+	ns.headscale.handlePollCommon(writer, req.Context(), machine, mapRequest, true)
 }