cloudflared-mirror/connection/protocol.go

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Go
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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
2021-11-12 15:38:06 +00:00
// 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)
}