TUN-3458: Upgrade to http2 when available, fallback to h2mux when we reach max retries

connection/connection.go

@@ -1,8 +1,6 @@
 package connection
 
 import (
-	"fmt"
-	"hash/fnv"
 	"io"
 	"net/http"
 	"strconv"
@@ -13,10 +11,6 @@ import (
 )
 
 const (
-	// edgeH2muxTLSServerName is the server name to establish h2mux connection with edge
-	edgeH2muxTLSServerName = "cftunnel.com"
-	// edgeH2TLSServerName is the server name to establish http2 connection with edge
-	edgeH2TLSServerName    = "h2.cftunnel.com"
 	lbProbeUserAgentPrefix = "Mozilla/5.0 (compatible; Cloudflare-Traffic-Manager/1.0; +https://www.cloudflare.com/traffic-manager/;"
 )
 
@@ -43,57 +37,6 @@ func (c *ClassicTunnelConfig) IsTrialZone() bool {
 	return c.Hostname == ""
 }
 
-type Protocol int64
-
-const (
-	H2mux Protocol = iota
-	HTTP2
-)
-
-func SelectProtocol(s string, accountTag string, http2Percentage uint32) (Protocol, bool) {
-	switch s {
-	case "h2mux":
-		return H2mux, true
-	case "http2":
-		return HTTP2, true
-	case "auto":
-		if tryHTTP2(accountTag, http2Percentage) {
-			return HTTP2, true
-		}
-		return H2mux, true
-	default:
-		return 0, false
-	}
-}
-
-func tryHTTP2(accountTag string, http2Percentage uint32) bool {
-	h := fnv.New32a()
-	h.Write([]byte(accountTag))
-	return h.Sum32()%100 < http2Percentage
-}
-
-func (p Protocol) ServerName() string {
-	switch p {
-	case H2mux:
-		return edgeH2muxTLSServerName
-	case HTTP2:
-		return edgeH2TLSServerName
-	default:
-		return ""
-	}
-}
-
-func (p Protocol) String() string {
-	switch p {
-	case H2mux:
-		return "h2mux"
-	case HTTP2:
-		return "http2"
-	default:
-		return fmt.Sprintf("unknown protocol")
-	}
-}
-
 type OriginClient interface {
 	Proxy(w ResponseWriter, req *http.Request, isWebsocket bool) error
 }

connection/http2.go

@@ -37,7 +37,7 @@ type HTTP2Connection struct {
 	connectedFuse ConnectedFuse
 }
 
-func NewHTTP2Connection(conn net.Conn, config *Config, originURL *url.URL, namedTunnelConfig *NamedTunnelConfig, connOptions *tunnelpogs.ConnectionOptions, observer *Observer, connIndex uint8, connectedFuse ConnectedFuse) (*HTTP2Connection, error) {
+func NewHTTP2Connection(conn net.Conn, config *Config, originURL *url.URL, namedTunnelConfig *NamedTunnelConfig, connOptions *tunnelpogs.ConnectionOptions, observer *Observer, connIndex uint8, connectedFuse ConnectedFuse) *HTTP2Connection {
 	return &HTTP2Connection{
 		conn: conn,
 		server: &http2.Server{
@@ -52,7 +52,7 @@ func NewHTTP2Connection(conn net.Conn, config *Config, originURL *url.URL, named
 		connIndex:     connIndex,
 		wg:            &sync.WaitGroup{},
 		connectedFuse: connectedFuse,
-	}, nil
+	}
 }
 
 func (c *HTTP2Connection) Serve(ctx context.Context) {

connection/metrics.go

@@ -299,7 +299,7 @@ func convertRTTMilliSec(t time.Duration) float64 {
 }
 
 // Metrics that can be collected without asking the edge
-func newTunnelMetrics(protocol Protocol) *tunnelMetrics {
+func newTunnelMetrics() *tunnelMetrics {
 	maxConcurrentRequestsPerTunnel := prometheus.NewGaugeVec(
 		prometheus.GaugeOpts{
 			Namespace: MetricsNamespace,
@@ -374,16 +374,12 @@ func newTunnelMetrics(protocol Protocol) *tunnelMetrics {
 		[]string{"rpcName"},
 	)
 	prometheus.MustRegister(registerSuccess)
-	var muxerMetrics *muxerMetrics
-	if protocol == H2mux {
-		muxerMetrics = newMuxerMetrics()
-	}
 
 	return &tunnelMetrics{
 		timerRetries:        timerRetries,
 		serverLocations:     serverLocations,
 		oldServerLocations:  make(map[string]string),
-		muxerMetrics:        muxerMetrics,
+		muxerMetrics:        newMuxerMetrics(),
 		tunnelsHA:           NewTunnelsForHA(),
 		regSuccess:          registerSuccess,
 		regFail:             registerFail,

connection/observer.go

@@ -16,10 +16,10 @@ type Observer struct {
 	tunnelEventChan chan<- ui.TunnelEvent
 }
 
-func NewObserver(logger logger.Service, tunnelEventChan chan<- ui.TunnelEvent, protocol Protocol) *Observer {
+func NewObserver(logger logger.Service, tunnelEventChan chan<- ui.TunnelEvent) *Observer {
 	return &Observer{
 		logger,
-		newTunnelMetrics(protocol),
+		newTunnelMetrics(),
 		tunnelEventChan,
 	}
 }

connection/observer_test.go

@@ -9,7 +9,7 @@ import (
 )
 
 // can only be called once
-var m = newTunnelMetrics(H2mux)
+var m = newTunnelMetrics()
 
 func TestRegisterServerLocation(t *testing.T) {
 	tunnels := 20

connection/protocol.go

@@ -0,0 +1,179 @@
+package connection
+
+import (
+	"fmt"
+	"hash/fnv"
+	"sync"
+	"time"
+
+	"github.com/cloudflare/cloudflared/logger"
+)
+
+const (
+	AvailableProtocolFlagMessage = "Available protocols: http2 - Go's implementation, h2mux - Cloudflare's implementation of HTTP/2, and auto - automatically select between http2 and h2mux"
+	// edgeH2muxTLSServerName is the server name to establish h2mux connection with edge
+	edgeH2muxTLSServerName = "cftunnel.com"
+	// edgeH2TLSServerName is the server name to establish http2 connection with edge
+	edgeH2TLSServerName = "h2.cftunnel.com"
+	// threshold to switch back to h2mux when the user intentionally pick --protocol http2
+	explicitHTTP2FallbackThreshold = -1
+	autoSelectFlag                 = "auto"
+)
+
+var (
+	ProtocolList = []Protocol{H2mux, HTTP2}
+)
+
+type Protocol int64
+
+const (
+	H2mux Protocol = iota
+	HTTP2
+)
+
+func (p Protocol) ServerName() string {
+	switch p {
+	case H2mux:
+		return edgeH2muxTLSServerName
+	case HTTP2:
+		return edgeH2TLSServerName
+	default:
+		return ""
+	}
+}
+
+// Fallback returns the fallback protocol and whether the protocol has a fallback
+func (p Protocol) fallback() (Protocol, bool) {
+	switch p {
+	case H2mux:
+		return 0, false
+	case HTTP2:
+		return H2mux, true
+	default:
+		return 0, false
+	}
+}
+
+func (p Protocol) String() string {
+	switch p {
+	case H2mux:
+		return "h2mux"
+	case HTTP2:
+		return "http2"
+	default:
+		return fmt.Sprintf("unknown protocol")
+	}
+}
+
+type ProtocolSelector interface {
+	Current() Protocol
+	Fallback() (Protocol, bool)
+}
+
+type staticProtocolSelector struct {
+	current Protocol
+}
+
+func (s *staticProtocolSelector) Current() Protocol {
+	return s.current
+}
+
+func (s *staticProtocolSelector) Fallback() (Protocol, bool) {
+	return 0, false
+}
+
+type autoProtocolSelector struct {
+	lock           sync.RWMutex
+	current        Protocol
+	switchThrehold int32
+	fetchFunc      PercentageFetcher
+	refreshAfter   time.Time
+	ttl            time.Duration
+	logger         logger.Service
+}
+
+func newAutoProtocolSelector(
+	current Protocol,
+	switchThrehold int32,
+	fetchFunc PercentageFetcher,
+	ttl time.Duration,
+	logger logger.Service,
+) *autoProtocolSelector {
+	return &autoProtocolSelector{
+		current:        current,
+		switchThrehold: switchThrehold,
+		fetchFunc:      fetchFunc,
+		refreshAfter:   time.Now().Add(ttl),
+		ttl:            ttl,
+		logger:         logger,
+	}
+}
+
+func (s *autoProtocolSelector) Current() Protocol {
+	s.lock.Lock()
+	defer s.lock.Unlock()
+	if time.Now().Before(s.refreshAfter) {
+		return s.current
+	}
+
+	percentage, err := s.fetchFunc()
+	if err != nil {
+		s.logger.Errorf("Failed to refresh protocol, err: %v", err)
+		return s.current
+	}
+
+	if s.switchThrehold < percentage {
+		s.current = HTTP2
+	} else {
+		s.current = H2mux
+	}
+	s.refreshAfter = time.Now().Add(s.ttl)
+	return s.current
+}
+
+func (s *autoProtocolSelector) Fallback() (Protocol, bool) {
+	s.lock.RLock()
+	defer s.lock.RUnlock()
+	return s.current.fallback()
+}
+
+type PercentageFetcher func() (int32, error)
+
+func NewProtocolSelector(protocolFlag string, namedTunnel *NamedTunnelConfig, fetchFunc PercentageFetcher, ttl time.Duration, logger logger.Service) (ProtocolSelector, error) {
+	if namedTunnel == nil {
+		return &staticProtocolSelector{
+			current: H2mux,
+		}, nil
+	}
+	if protocolFlag == H2mux.String() {
+		return &staticProtocolSelector{
+			current: H2mux,
+		}, nil
+	}
+
+	http2Percentage, err := fetchFunc()
+	if err != nil {
+		return nil, err
+	}
+	if protocolFlag == HTTP2.String() {
+		if http2Percentage < 0 {
+			return newAutoProtocolSelector(H2mux, explicitHTTP2FallbackThreshold, fetchFunc, ttl, logger), nil
+		}
+		return newAutoProtocolSelector(HTTP2, explicitHTTP2FallbackThreshold, fetchFunc, ttl, logger), nil
+	}
+
+	if protocolFlag != autoSelectFlag {
+		return nil, fmt.Errorf("Unknown protocol %s, %s", protocolFlag, AvailableProtocolFlagMessage)
+	}
+	threshold := switchThreshold(namedTunnel.Auth.AccountTag)
+	if threshold < http2Percentage {
+		return newAutoProtocolSelector(HTTP2, threshold, fetchFunc, ttl, logger), nil
+	}
+	return newAutoProtocolSelector(H2mux, threshold, fetchFunc, ttl, logger), nil
+}
+
+func switchThreshold(accountTag string) int32 {
+	h := fnv.New32a()
+	h.Write([]byte(accountTag))
+	return int32(h.Sum32() % 100)
+}

connection/protocol_test.go

@@ -0,0 +1,220 @@
+package connection
+
+import (
+	"fmt"
+	"testing"
+	"time"
+
+	"github.com/cloudflare/cloudflared/logger"
+	"github.com/cloudflare/cloudflared/tunnelrpc/pogs"
+	"github.com/stretchr/testify/assert"
+)
+
+const (
+	testNoTTL = 0
+)
+
+var (
+	testNamedTunnelConfig = &NamedTunnelConfig{
+		Auth: pogs.TunnelAuth{
+			AccountTag: "testAccountTag",
+		},
+	}
+)
+
+func mockFetcher(percentage int32) PercentageFetcher {
+	return func() (int32, error) {
+		return percentage, nil
+	}
+}
+
+func mockFetcherWithError() PercentageFetcher {
+	return func() (int32, error) {
+		return 0, fmt.Errorf("failed to fetch precentage")
+	}
+}
+
+type dynamicMockFetcher struct {
+	percentage int32
+	err        error
+}
+
+func (dmf *dynamicMockFetcher) fetch() PercentageFetcher {
+	return func() (int32, error) {
+		if dmf.err != nil {
+			return 0, dmf.err
+		}
+		return dmf.percentage, nil
+	}
+}
+
+func TestNewProtocolSelector(t *testing.T) {
+	tests := []struct {
+		name              string
+		protocol          string
+		expectedProtocol  Protocol
+		hasFallback       bool
+		expectedFallback  Protocol
+		namedTunnelConfig *NamedTunnelConfig
+		fetchFunc         PercentageFetcher
+		wantErr           bool
+	}{
+		{
+			name:              "classic tunnel",
+			protocol:          "h2mux",
+			expectedProtocol:  H2mux,
+			namedTunnelConfig: nil,
+		},
+		{
+			name:              "named tunnel over h2mux",
+			protocol:          "h2mux",
+			expectedProtocol:  H2mux,
+			namedTunnelConfig: testNamedTunnelConfig,
+		},
+		{
+			name:              "named tunnel over http2",
+			protocol:          "http2",
+			expectedProtocol:  HTTP2,
+			hasFallback:       true,
+			expectedFallback:  H2mux,
+			fetchFunc:         mockFetcher(0),
+			namedTunnelConfig: testNamedTunnelConfig,
+		},
+		{
+			name:              "named tunnel http2 disabled",
+			protocol:          "http2",
+			expectedProtocol:  H2mux,
+			fetchFunc:         mockFetcher(-1),
+			namedTunnelConfig: testNamedTunnelConfig,
+		},
+		{
+			name:              "named tunnel auto all http2 disabled",
+			protocol:          "auto",
+			expectedProtocol:  H2mux,
+			fetchFunc:         mockFetcher(-1),
+			namedTunnelConfig: testNamedTunnelConfig,
+		},
+		{
+			name:              "named tunnel auto to h2mux",
+			protocol:          "auto",
+			expectedProtocol:  H2mux,
+			fetchFunc:         mockFetcher(0),
+			namedTunnelConfig: testNamedTunnelConfig,
+		},
+		{
+			name:              "named tunnel auto to http2",
+			protocol:          "auto",
+			expectedProtocol:  HTTP2,
+			hasFallback:       true,
+			expectedFallback:  H2mux,
+			fetchFunc:         mockFetcher(100),
+			namedTunnelConfig: testNamedTunnelConfig,
+		},
+		{
+			// None named tunnel can only use h2mux, so specifying an unknown protocol is not an error
+			name:             "classic tunnel unknown protocol",
+			protocol:         "unknown",
+			expectedProtocol: H2mux,
+		},
+		{
+			name:              "named tunnel unknown protocol",
+			protocol:          "unknown",
+			fetchFunc:         mockFetcher(100),
+			namedTunnelConfig: testNamedTunnelConfig,
+			wantErr:           true,
+		},
+		{
+			name:              "named tunnel fetch error",
+			protocol:          "unknown",
+			fetchFunc:         mockFetcherWithError(),
+			namedTunnelConfig: testNamedTunnelConfig,
+			wantErr:           true,
+		},
+	}
+	logger, _ := logger.New()
+	for _, test := range tests {
+		selector, err := NewProtocolSelector(test.protocol, test.namedTunnelConfig, test.fetchFunc, testNoTTL, logger)
+		if test.wantErr {
+			assert.Error(t, err, fmt.Sprintf("test %s failed", test.name))
+		} else {
+			assert.NoError(t, err, fmt.Sprintf("test %s failed", test.name))
+			assert.Equal(t, test.expectedProtocol, selector.Current(), fmt.Sprintf("test %s failed", test.name))
+			fallback, ok := selector.Fallback()
+			assert.Equal(t, test.hasFallback, ok, fmt.Sprintf("test %s failed", test.name))
+			if test.hasFallback {
+				assert.Equal(t, test.expectedFallback, fallback, fmt.Sprintf("test %s failed", test.name))
+			}
+		}
+	}
+}
+
+func TestAutoProtocolSelectorRefresh(t *testing.T) {
+	logger, _ := logger.New()
+	fetcher := dynamicMockFetcher{}
+	selector, err := NewProtocolSelector("auto", testNamedTunnelConfig, fetcher.fetch(), testNoTTL, logger)
+	assert.NoError(t, err)
+	assert.Equal(t, H2mux, selector.Current())
+
+	fetcher.percentage = 100
+	assert.Equal(t, HTTP2, selector.Current())
+
+	fetcher.percentage = 0
+	assert.Equal(t, H2mux, selector.Current())
+
+	fetcher.percentage = 100
+	assert.Equal(t, HTTP2, selector.Current())
+
+	fetcher.err = fmt.Errorf("failed to fetch")
+	assert.Equal(t, HTTP2, selector.Current())
+
+	fetcher.percentage = -1
+	fetcher.err = nil
+	assert.Equal(t, H2mux, selector.Current())
+
+	fetcher.percentage = 0
+	assert.Equal(t, H2mux, selector.Current())
+
+	fetcher.percentage = 100
+	assert.Equal(t, HTTP2, selector.Current())
+}
+
+func TestHTTP2ProtocolSelectorRefresh(t *testing.T) {
+	logger, _ := logger.New()
+	fetcher := dynamicMockFetcher{}
+	selector, err := NewProtocolSelector("http2", testNamedTunnelConfig, fetcher.fetch(), testNoTTL, logger)
+	assert.NoError(t, err)
+	assert.Equal(t, HTTP2, selector.Current())
+
+	fetcher.percentage = 100
+	assert.Equal(t, HTTP2, selector.Current())
+
+	fetcher.percentage = 0
+	assert.Equal(t, HTTP2, selector.Current())
+
+	fetcher.err = fmt.Errorf("failed to fetch")
+	assert.Equal(t, HTTP2, selector.Current())
+
+	fetcher.percentage = -1
+	fetcher.err = nil
+	assert.Equal(t, H2mux, selector.Current())
+
+	fetcher.percentage = 0
+	assert.Equal(t, HTTP2, selector.Current())
+
+	fetcher.percentage = 100
+	assert.Equal(t, HTTP2, selector.Current())
+
+	fetcher.percentage = -1
+	assert.Equal(t, H2mux, selector.Current())
+}
+
+func TestProtocolSelectorRefreshTTL(t *testing.T) {
+	logger, _ := logger.New()
+	fetcher := dynamicMockFetcher{percentage: 100}
+	selector, err := NewProtocolSelector("auto", testNamedTunnelConfig, fetcher.fetch(), time.Hour, logger)
+	assert.NoError(t, err)
+	assert.Equal(t, HTTP2, selector.Current())
+
+	fetcher.percentage = 0
+	assert.Equal(t, HTTP2, selector.Current())
+}