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" // edgeH2muxTLSServerName is the server name to establish h2mux connection with edge (unused, but kept for legacy reference). 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" // SRV and TXT record resolution TTL ResolveTTL = time.Hour ) var ( // ProtocolList represents a list of supported protocols for communication with the edge // in order of precedence for remote percentage fetcher. ProtocolList = []Protocol{QUIC, HTTP2} ) type Protocol int64 const ( // HTTP2 using golang HTTP2 library for edge connections. HTTP2 Protocol = iota // QUIC using quic-go for edge connections. QUIC ) // Fallback returns the fallback protocol and whether the protocol has a fallback func (p Protocol) fallback() (Protocol, bool) { switch p { case HTTP2: return 0, false case QUIC: return HTTP2, true default: return 0, false } } func (p Protocol) String() string { switch p { case HTTP2: return "http2" case QUIC: return "quic" default: return fmt.Sprintf("unknown protocol") } } func (p Protocol) TLSSettings() *TLSSettings { switch p { case HTTP2: return &TLSSettings{ ServerName: edgeH2TLSServerName, } case QUIC: 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) } // staticProtocolSelector will not provide a different protocol for Fallback type staticProtocolSelector struct { current Protocol } func (s *staticProtocolSelector) Current() Protocol { return s.current } func (s *staticProtocolSelector) Fallback() (Protocol, bool) { return s.current, false } // remoteProtocolSelector will fetch a list of remote protocols to provide for edge discovery type remoteProtocolSelector 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 edgediscovery.PercentageFetcher refreshAfter time.Time ttl time.Duration log *zerolog.Logger } func newRemoteProtocolSelector( current Protocol, protocolPool []Protocol, switchThreshold int32, fetchFunc edgediscovery.PercentageFetcher, ttl time.Duration, log *zerolog.Logger, ) *remoteProtocolSelector { return &remoteProtocolSelector{ current: current, protocolPool: protocolPool, switchThreshold: switchThreshold, fetchFunc: fetchFunc, refreshAfter: time.Now().Add(ttl), ttl: ttl, log: log, } } func (s *remoteProtocolSelector) 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 (s *remoteProtocolSelector) Fallback() (Protocol, bool) { s.lock.RLock() defer s.lock.RUnlock() return s.current.fallback() } func getProtocol(protocolPool []Protocol, fetchFunc edgediscovery.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 } } // Default to first index in protocolPool list return protocolPool[0], nil } // defaultProtocolSelector will allow for a protocol to have a fallback type defaultProtocolSelector struct { lock sync.RWMutex current Protocol } func newDefaultProtocolSelector( current Protocol, ) *defaultProtocolSelector { return &defaultProtocolSelector{ current: current, } } func (s *defaultProtocolSelector) Current() Protocol { s.lock.Lock() defer s.lock.Unlock() return s.current } func (s *defaultProtocolSelector) Fallback() (Protocol, bool) { s.lock.RLock() defer s.lock.RUnlock() return s.current.fallback() } func NewProtocolSelector( protocolFlag string, accountTag string, tunnelTokenProvided bool, needPQ bool, protocolFetcher edgediscovery.PercentageFetcher, resolveTTL time.Duration, log *zerolog.Logger, ) (ProtocolSelector, error) { // With --post-quantum, we force quic if needPQ { return &staticProtocolSelector{ current: QUIC, }, nil } threshold := switchThreshold(accountTag) fetchedProtocol, err := getProtocol(ProtocolList, protocolFetcher, threshold) log.Debug().Msgf("Fetched protocol: %s", fetchedProtocol) if err != nil { log.Warn().Msg("Unable to lookup protocol percentage.") // Falling through here since 'auto' is handled in the switch and failing // to do the protocol lookup isn't a failure since it can be triggered again // after the TTL. } // If the user picks a protocol, then we stick to it no matter what. switch protocolFlag { case "h2mux": // Any users still requesting h2mux will be upgraded to http2 instead log.Warn().Msg("h2mux is no longer a supported protocol: upgrading edge connection to http2. Please remove '--protocol h2mux' from runtime arguments to remove this warning.") return &staticProtocolSelector{current: HTTP2}, nil case QUIC.String(): return &staticProtocolSelector{current: QUIC}, nil case HTTP2.String(): return &staticProtocolSelector{current: HTTP2}, nil case AutoSelectFlag: // When a --token is provided, we want to start with QUIC but have fallback to HTTP2 if tunnelTokenProvided { return newDefaultProtocolSelector(QUIC), nil } return newRemoteProtocolSelector(fetchedProtocol, ProtocolList, threshold, protocolFetcher, resolveTTL, 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) }