cloudflared-mirror/supervisor/supervisor.go

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package supervisor
import (
"context"
"errors"
"fmt"
"time"
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"github.com/google/uuid"
"github.com/rs/zerolog"
"github.com/cloudflare/cloudflared/connection"
"github.com/cloudflare/cloudflared/edgediscovery"
"github.com/cloudflare/cloudflared/edgediscovery/allregions"
"github.com/cloudflare/cloudflared/h2mux"
"github.com/cloudflare/cloudflared/orchestration"
"github.com/cloudflare/cloudflared/retry"
"github.com/cloudflare/cloudflared/signal"
tunnelpogs "github.com/cloudflare/cloudflared/tunnelrpc/pogs"
)
const (
// SRV and TXT record resolution TTL
ResolveTTL = time.Hour
// Waiting time before retrying a failed tunnel connection
tunnelRetryDuration = time.Second * 10
// Interval between registering new tunnels
registrationInterval = time.Second
subsystemRefreshAuth = "refresh_auth"
// Maximum exponent for 'Authenticate' exponential backoff
refreshAuthMaxBackoff = 10
// Waiting time before retrying a failed 'Authenticate' connection
refreshAuthRetryDuration = time.Second * 10
)
// Supervisor manages non-declarative tunnels. Establishes TCP connections with the edge, and
// reconnects them if they disconnect.
type Supervisor struct {
cloudflaredUUID uuid.UUID
config *TunnelConfig
orchestrator *orchestration.Orchestrator
edgeIPs *edgediscovery.Edge
edgeTunnelServer EdgeTunnelServer
tunnelErrors chan tunnelError
tunnelsConnecting map[int]chan struct{}
// nextConnectedIndex and nextConnectedSignal are used to wait for all
// currently-connecting tunnels to finish connecting so we can reset backoff timer
nextConnectedIndex int
nextConnectedSignal chan struct{}
log *ConnAwareLogger
logTransport *zerolog.Logger
reconnectCredentialManager *reconnectCredentialManager
useReconnectToken bool
reconnectCh chan ReconnectSignal
gracefulShutdownC <-chan struct{}
}
var errEarlyShutdown = errors.New("shutdown started")
type tunnelError struct {
index int
err error
}
func NewSupervisor(config *TunnelConfig, orchestrator *orchestration.Orchestrator, reconnectCh chan ReconnectSignal, gracefulShutdownC <-chan struct{}) (*Supervisor, error) {
cloudflaredUUID, err := uuid.NewRandom()
if err != nil {
return nil, fmt.Errorf("failed to generate cloudflared instance ID: %w", err)
}
var edgeIPs *edgediscovery.Edge
if len(config.EdgeAddrs) > 0 {
edgeIPs, err = edgediscovery.StaticEdge(config.Log, config.EdgeAddrs)
} else {
edgeIPs, err = edgediscovery.ResolveEdge(config.Log, config.Region, config.EdgeIPVersion)
}
if err != nil {
return nil, err
}
reconnectCredentialManager := newReconnectCredentialManager(connection.MetricsNamespace, connection.TunnelSubsystem, config.HAConnections)
log := NewConnAwareLogger(config.Log, config.Observer)
var edgeAddrHandler EdgeAddrHandler
if config.EdgeIPVersion == allregions.IPv6Only || config.EdgeIPVersion == allregions.Auto {
edgeAddrHandler = &IPAddrFallback{}
} else { // IPv4Only
edgeAddrHandler = &DefaultAddrFallback{}
}
edgeTunnelServer := EdgeTunnelServer{
config: config,
cloudflaredUUID: cloudflaredUUID,
orchestrator: orchestrator,
credentialManager: reconnectCredentialManager,
edgeAddrs: edgeIPs,
edgeAddrHandler: edgeAddrHandler,
reconnectCh: reconnectCh,
gracefulShutdownC: gracefulShutdownC,
connAwareLogger: log,
}
useReconnectToken := false
if config.ClassicTunnel != nil {
useReconnectToken = config.ClassicTunnel.UseReconnectToken
}
return &Supervisor{
cloudflaredUUID: cloudflaredUUID,
config: config,
orchestrator: orchestrator,
edgeIPs: edgeIPs,
edgeTunnelServer: edgeTunnelServer,
tunnelErrors: make(chan tunnelError),
tunnelsConnecting: map[int]chan struct{}{},
log: log,
logTransport: config.LogTransport,
reconnectCredentialManager: reconnectCredentialManager,
useReconnectToken: useReconnectToken,
reconnectCh: reconnectCh,
gracefulShutdownC: gracefulShutdownC,
}, nil
}
func (s *Supervisor) Run(
ctx context.Context,
connectedSignal *signal.Signal,
) error {
if err := s.initialize(ctx, connectedSignal); err != nil {
if err == errEarlyShutdown {
return nil
}
return err
}
var tunnelsWaiting []int
tunnelsActive := s.config.HAConnections
backoff := retry.BackoffHandler{MaxRetries: s.config.Retries, BaseTime: tunnelRetryDuration, RetryForever: true}
var backoffTimer <-chan time.Time
refreshAuthBackoff := &retry.BackoffHandler{MaxRetries: refreshAuthMaxBackoff, BaseTime: refreshAuthRetryDuration, RetryForever: true}
var refreshAuthBackoffTimer <-chan time.Time
if s.useReconnectToken {
if timer, err := s.reconnectCredentialManager.RefreshAuth(ctx, refreshAuthBackoff, s.authenticate); err == nil {
refreshAuthBackoffTimer = timer
} else {
s.log.Logger().Err(err).
Dur("refreshAuthRetryDuration", refreshAuthRetryDuration).
Msgf("supervisor: initial refreshAuth failed, retrying in %v", refreshAuthRetryDuration)
refreshAuthBackoffTimer = time.After(refreshAuthRetryDuration)
}
}
shuttingDown := false
for {
select {
// Context cancelled
case <-ctx.Done():
for tunnelsActive > 0 {
<-s.tunnelErrors
tunnelsActive--
}
return nil
// startTunnel completed with a response
// (note that this may also be caused by context cancellation)
case tunnelError := <-s.tunnelErrors:
tunnelsActive--
if tunnelError.err != nil && !shuttingDown {
switch tunnelError.err.(type) {
case ReconnectSignal:
// For tunnels that closed with reconnect signal, we reconnect immediately
go s.startTunnel(ctx, tunnelError.index, s.newConnectedTunnelSignal(tunnelError.index))
tunnelsActive++
continue
}
s.log.ConnAwareLogger().Err(tunnelError.err).Int(connection.LogFieldConnIndex, tunnelError.index).Msg("Connection terminated")
tunnelsWaiting = append(tunnelsWaiting, tunnelError.index)
s.waitForNextTunnel(tunnelError.index)
if backoffTimer == nil {
backoffTimer = backoff.BackoffTimer()
}
} else if tunnelsActive == 0 {
s.log.ConnAwareLogger().Msg("no more connections active and exiting")
// All connected tunnels exited gracefully, no more work to do
return nil
}
// Backoff was set and its timer expired
case <-backoffTimer:
backoffTimer = nil
for _, index := range tunnelsWaiting {
go s.startTunnel(ctx, index, s.newConnectedTunnelSignal(index))
}
tunnelsActive += len(tunnelsWaiting)
tunnelsWaiting = nil
// Time to call Authenticate
case <-refreshAuthBackoffTimer:
newTimer, err := s.reconnectCredentialManager.RefreshAuth(ctx, refreshAuthBackoff, s.authenticate)
if err != nil {
s.log.Logger().Err(err).Msg("supervisor: Authentication failed")
// Permanent failure. Leave the `select` without setting the
// channel to be non-null, so we'll never hit this case of the `select` again.
continue
}
refreshAuthBackoffTimer = newTimer
// Tunnel successfully connected
case <-s.nextConnectedSignal:
if !s.waitForNextTunnel(s.nextConnectedIndex) && len(tunnelsWaiting) == 0 {
// No more tunnels outstanding, clear backoff timer
backoff.SetGracePeriod()
}
case <-s.gracefulShutdownC:
shuttingDown = true
}
}
}
// Returns nil if initialization succeeded, else the initialization error.
// Attempts here will be made to connect one tunnel, if successful, it will
// connect the available tunnels up to config.HAConnections.
func (s *Supervisor) initialize(
ctx context.Context,
connectedSignal *signal.Signal,
) error {
availableAddrs := s.edgeIPs.AvailableAddrs()
if s.config.HAConnections > availableAddrs {
s.log.Logger().Info().Msgf("You requested %d HA connections but I can give you at most %d.", s.config.HAConnections, availableAddrs)
s.config.HAConnections = availableAddrs
}
go s.startFirstTunnel(ctx, connectedSignal)
// Wait for response from first tunnel before proceeding to attempt other HA edge tunnels
select {
case <-ctx.Done():
<-s.tunnelErrors
return ctx.Err()
case tunnelError := <-s.tunnelErrors:
return tunnelError.err
case <-s.gracefulShutdownC:
return errEarlyShutdown
case <-connectedSignal.Wait():
}
// At least one successful connection, so start the rest
for i := 1; i < s.config.HAConnections; i++ {
ch := signal.New(make(chan struct{}))
go s.startTunnel(ctx, i, ch)
time.Sleep(registrationInterval)
}
return nil
}
// startTunnel starts the first tunnel connection. The resulting error will be sent on
// s.tunnelErrors. It will send a signal via connectedSignal if registration succeed
func (s *Supervisor) startFirstTunnel(
ctx context.Context,
connectedSignal *signal.Signal,
) {
var (
err error
)
const firstConnIndex = 0
defer func() {
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s.tunnelErrors <- tunnelError{index: firstConnIndex, err: err}
}()
err = s.edgeTunnelServer.Serve(ctx, firstConnIndex, connectedSignal)
// If the first tunnel disconnects, keep restarting it.
for s.unusedIPs() {
if ctx.Err() != nil {
return
}
if err == nil {
return
}
err = s.edgeTunnelServer.Serve(ctx, firstConnIndex, connectedSignal)
}
}
// startTunnel starts a new tunnel connection. The resulting error will be sent on
// s.tunnelError as this is expected to run in a goroutine.
func (s *Supervisor) startTunnel(
ctx context.Context,
index int,
connectedSignal *signal.Signal,
) {
var (
err error
)
defer func() {
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s.tunnelErrors <- tunnelError{index: index, err: err}
}()
err = s.edgeTunnelServer.Serve(ctx, uint8(index), connectedSignal)
}
func (s *Supervisor) newConnectedTunnelSignal(index int) *signal.Signal {
sig := make(chan struct{})
s.tunnelsConnecting[index] = sig
s.nextConnectedSignal = sig
s.nextConnectedIndex = index
return signal.New(sig)
}
func (s *Supervisor) waitForNextTunnel(index int) bool {
delete(s.tunnelsConnecting, index)
s.nextConnectedSignal = nil
for k, v := range s.tunnelsConnecting {
s.nextConnectedIndex = k
s.nextConnectedSignal = v
return true
}
return false
}
func (s *Supervisor) unusedIPs() bool {
return s.edgeIPs.AvailableAddrs() > s.config.HAConnections
}
func (s *Supervisor) authenticate(ctx context.Context, numPreviousAttempts int) (tunnelpogs.AuthOutcome, error) {
arbitraryEdgeIP, err := s.edgeIPs.GetAddrForRPC()
if err != nil {
return nil, err
}
edgeConn, err := edgediscovery.DialEdge(ctx, dialTimeout, s.config.EdgeTLSConfigs[connection.H2mux], arbitraryEdgeIP.TCP)
if err != nil {
return nil, err
}
defer edgeConn.Close()
handler := h2mux.MuxedStreamFunc(func(*h2mux.MuxedStream) error {
// This callback is invoked by h2mux when the edge initiates a stream.
return nil // noop
})
muxerConfig := s.config.MuxerConfig.H2MuxerConfig(handler, s.logTransport)
muxer, err := h2mux.Handshake(edgeConn, edgeConn, *muxerConfig, h2mux.ActiveStreams)
if err != nil {
return nil, err
}
go muxer.Serve(ctx)
defer func() {
// If we don't wait for the muxer shutdown here, edgeConn.Close() runs before the muxer connections are done,
// and the user sees log noise: "error writing data", "connection closed unexpectedly"
<-muxer.Shutdown()
}()
stream, err := muxer.OpenRPCStream(ctx)
if err != nil {
return nil, err
}
rpcClient := connection.NewTunnelServerClient(ctx, stream, s.log.Logger())
defer rpcClient.Close()
const arbitraryConnectionID = uint8(0)
registrationOptions := s.config.registrationOptions(arbitraryConnectionID, edgeConn.LocalAddr().String(), s.cloudflaredUUID)
registrationOptions.NumPreviousAttempts = uint8(numPreviousAttempts)
return rpcClient.Authenticate(ctx, s.config.ClassicTunnel, registrationOptions)
}