package connection import ( "fmt" "hash/fnv" "sync" "time" "github.com/rs/zerolog" "github.com/cloudflare/cloudflared/edgediscovery" ) const ( AvailableProtocolFlagMessage = "Available protocols: 'auto' - automatically chooses the best protocol over time (the default; and also the recommended one); 'quic' - based on QUIC, relying on UDP egress to Cloudflare edge; 'http2' - using Go's HTTP2 library, relying on TCP egress to Cloudflare edge; 'h2mux' - Cloudflare's implementation of HTTP/2, deprecated" // 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" // edgeQUICServerName is the server name to establish quic connection with edge. edgeQUICServerName = "quic.cftunnel.com" autoSelectFlag = "auto" ) var ( // ProtocolList represents a list of supported protocols for communication with the edge. ProtocolList = []Protocol{H2mux, HTTP2, HTTP2Warp, QUIC, QUICWarp} ) type Protocol int64 const ( // H2mux protocol can be used both with Classic and Named Tunnels. . H2mux Protocol = iota // HTTP2 is used only with named tunnels. It's more efficient than H2mux for L4 proxying. HTTP2 // QUIC is used only with named tunnels. QUIC // HTTP2Warp is used only with named tunnels. It's useful for warp-routing where we don't want to fallback to // H2mux on HTTP2 failure to connect. HTTP2Warp //QUICWarp is used only with named tunnels. It's useful for warp-routing where we want to fallback to HTTP2 but // don't want HTTP2 to fallback to H2mux QUICWarp ) // 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 case HTTP2Warp: return 0, false case QUIC: return HTTP2, true case QUICWarp: return HTTP2Warp, true default: return 0, false } } func (p Protocol) String() string { switch p { case H2mux: return "h2mux" case HTTP2, HTTP2Warp: return "http2" case QUIC, QUICWarp: return "quic" default: return fmt.Sprintf("unknown protocol") } } func (p Protocol) TLSSettings() *TLSSettings { switch p { case H2mux: return &TLSSettings{ ServerName: edgeH2muxTLSServerName, } case HTTP2, HTTP2Warp: return &TLSSettings{ ServerName: edgeH2TLSServerName, } case QUIC, QUICWarp: return &TLSSettings{ ServerName: edgeQUICServerName, NextProtos: []string{"argotunnel"}, } default: return nil } } type TLSSettings struct { ServerName string NextProtos []string } 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 // protocolPool is desired protocols in the order of priority they should be picked in. protocolPool []Protocol switchThreshold int32 fetchFunc PercentageFetcher refreshAfter time.Time ttl time.Duration log *zerolog.Logger } func newAutoProtocolSelector( current Protocol, protocolPool []Protocol, switchThreshold int32, fetchFunc PercentageFetcher, ttl time.Duration, log *zerolog.Logger, ) *autoProtocolSelector { return &autoProtocolSelector{ current: current, protocolPool: protocolPool, switchThreshold: switchThreshold, fetchFunc: fetchFunc, refreshAfter: time.Now().Add(ttl), ttl: ttl, log: log, } } func (s *autoProtocolSelector) Current() Protocol { s.lock.Lock() defer s.lock.Unlock() if time.Now().Before(s.refreshAfter) { return s.current } protocol, err := getProtocol(s.protocolPool, s.fetchFunc, s.switchThreshold) if err != nil { s.log.Err(err).Msg("Failed to refresh protocol") return s.current } s.current = protocol s.refreshAfter = time.Now().Add(s.ttl) return s.current } func getProtocol(protocolPool []Protocol, fetchFunc PercentageFetcher, switchThreshold int32) (Protocol, error) { protocolPercentages, err := fetchFunc() if err != nil { return 0, err } for _, protocol := range protocolPool { protocolPercentage := protocolPercentages.GetPercentage(protocol.String()) if protocolPercentage > switchThreshold { return protocol, nil } } return protocolPool[len(protocolPool)-1], nil } func (s *autoProtocolSelector) Fallback() (Protocol, bool) { s.lock.RLock() defer s.lock.RUnlock() return s.current.fallback() } type PercentageFetcher func() (edgediscovery.ProtocolPercents, error) func NewProtocolSelector( protocolFlag string, warpRoutingEnabled bool, namedTunnel *NamedTunnelProperties, fetchFunc PercentageFetcher, ttl time.Duration, log *zerolog.Logger, ) (ProtocolSelector, error) { // Classic tunnel is only supported with h2mux if namedTunnel == nil { return &staticProtocolSelector{ current: H2mux, }, nil } threshold := switchThreshold(namedTunnel.Credentials.AccountTag) fetchedProtocol, err := getProtocol([]Protocol{QUIC, HTTP2}, fetchFunc, threshold) if err != nil { log.Err(err).Msg("Unable to lookup protocol. Defaulting to `http2`. If this fails, you can set `--protocol h2mux` in your cloudflared command.") return &staticProtocolSelector{ current: HTTP2, }, nil } if warpRoutingEnabled { if protocolFlag == H2mux.String() || fetchedProtocol == H2mux { log.Warn().Msg("Warp routing is not supported in h2mux protocol. Upgrading to http2 to allow it.") protocolFlag = HTTP2.String() fetchedProtocol = HTTP2Warp } return selectWarpRoutingProtocols(protocolFlag, fetchFunc, ttl, log, threshold, fetchedProtocol) } return selectNamedTunnelProtocols(protocolFlag, fetchFunc, ttl, log, threshold, fetchedProtocol) } func selectNamedTunnelProtocols( protocolFlag string, fetchFunc PercentageFetcher, ttl time.Duration, log *zerolog.Logger, threshold int32, protocol Protocol, ) (ProtocolSelector, error) { // If the user picks a protocol, then we stick to it no matter what. switch protocolFlag { case H2mux.String(): return &staticProtocolSelector{current: H2mux}, nil case QUIC.String(): return &staticProtocolSelector{current: QUIC}, nil case HTTP2.String(): return &staticProtocolSelector{current: HTTP2}, nil } // If the user does not pick (hopefully the majority) then we use the one derived from the TXT DNS record and // fallback on failures. if protocolFlag == autoSelectFlag { return newAutoProtocolSelector(protocol, []Protocol{QUIC, HTTP2, H2mux}, threshold, fetchFunc, ttl, log), nil } return nil, fmt.Errorf("Unknown protocol %s, %s", protocolFlag, AvailableProtocolFlagMessage) } func selectWarpRoutingProtocols( protocolFlag string, fetchFunc PercentageFetcher, ttl time.Duration, log *zerolog.Logger, threshold int32, protocol Protocol, ) (ProtocolSelector, error) { // If the user picks a protocol, then we stick to it no matter what. switch protocolFlag { case QUIC.String(): return &staticProtocolSelector{current: QUICWarp}, nil case HTTP2.String(): return &staticProtocolSelector{current: HTTP2Warp}, nil } // If the user does not pick (hopefully the majority) then we use the one derived from the TXT DNS record and // fallback on failures. if protocolFlag == autoSelectFlag { return newAutoProtocolSelector(protocol, []Protocol{QUICWarp, HTTP2Warp}, threshold, fetchFunc, ttl, log), nil } return nil, fmt.Errorf("Unknown protocol %s, %s", protocolFlag, AvailableProtocolFlagMessage) } func switchThreshold(accountTag string) int32 { h := fnv.New32a() _, _ = h.Write([]byte(accountTag)) return int32(h.Sum32() % 100) }