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controller.go
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controller.go
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/*
* Copyright (c) 2015, Psiphon Inc.
* All rights reserved.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*/
// Package psiphon implements the core tunnel functionality of a Psiphon client.
// The main function is RunForever, which runs a Controller that obtains lists of
// servers, establishes tunnel connections, and runs local proxies through which
// tunneled traffic may be sent.
package psiphon
import (
"context"
"errors"
"fmt"
"math/rand"
"net"
"sync"
"time"
"github.com/Psiphon-Labs/goarista/monotime"
"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common"
"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/parameters"
"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/prng"
"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/protocol"
"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/tactics"
"github.com/Psiphon-Labs/psiphon-tunnel-core/psiphon/common/tun"
)
// Controller is a tunnel lifecycle coordinator. It manages lists of servers to
// connect to; establishes and monitors tunnels; and runs local proxies which
// route traffic through the tunnels.
type Controller struct {
config *Config
runCtx context.Context
stopRunning context.CancelFunc
runWaitGroup *sync.WaitGroup
connectedTunnels chan *Tunnel
failedTunnels chan *Tunnel
tunnelMutex sync.Mutex
establishedOnce bool
tunnels []*Tunnel
nextTunnel int
startedConnectedReporter bool
isEstablishing bool
protocolSelectionConstraints *protocolSelectionConstraints
concurrentEstablishTunnelsMutex sync.Mutex
establishConnectTunnelCount int
concurrentEstablishTunnels int
concurrentIntensiveEstablishTunnels int
peakConcurrentEstablishTunnels int
peakConcurrentIntensiveEstablishTunnels int
establishCtx context.Context
stopEstablish context.CancelFunc
establishWaitGroup *sync.WaitGroup
candidateServerEntries chan *candidateServerEntry
untunneledDialConfig *DialConfig
splitTunnelClassifier *SplitTunnelClassifier
signalFetchCommonRemoteServerList chan struct{}
signalFetchObfuscatedServerLists chan struct{}
signalDownloadUpgrade chan string
signalReportConnected chan struct{}
serverAffinityDoneBroadcast chan struct{}
packetTunnelClient *tun.Client
packetTunnelTransport *PacketTunnelTransport
staggerMutex sync.Mutex
}
// NewController initializes a new controller.
func NewController(config *Config) (controller *Controller, err error) {
if !config.IsCommitted() {
return nil, common.ContextError(errors.New("uncommitted config"))
}
// Needed by regen, at least
rand.Seed(int64(time.Now().Nanosecond()))
// The session ID for the Psiphon server API is used across all
// tunnels established by the controller.
NoticeSessionId(config.SessionID)
untunneledDialConfig := &DialConfig{
UpstreamProxyURL: config.UpstreamProxyURL,
CustomHeaders: config.CustomHeaders,
DeviceBinder: config.deviceBinder,
DnsServerGetter: config.DnsServerGetter,
IPv6Synthesizer: config.IPv6Synthesizer,
TrustedCACertificatesFilename: config.TrustedCACertificatesFilename,
}
controller = &Controller{
config: config,
runWaitGroup: new(sync.WaitGroup),
// connectedTunnels and failedTunnels buffer sizes are large enough to
// receive full pools of tunnels without blocking. Senders should not block.
connectedTunnels: make(chan *Tunnel, config.TunnelPoolSize),
failedTunnels: make(chan *Tunnel, config.TunnelPoolSize),
tunnels: make([]*Tunnel, 0),
establishedOnce: false,
startedConnectedReporter: false,
isEstablishing: false,
untunneledDialConfig: untunneledDialConfig,
// TODO: Add a buffer of 1 so we don't miss a signal while receiver is
// starting? Trade-off is potential back-to-back fetch remotes. As-is,
// establish will eventually signal another fetch remote.
signalFetchCommonRemoteServerList: make(chan struct{}),
signalFetchObfuscatedServerLists: make(chan struct{}),
signalDownloadUpgrade: make(chan string),
signalReportConnected: make(chan struct{}),
}
controller.splitTunnelClassifier = NewSplitTunnelClassifier(config, controller)
if config.PacketTunnelTunFileDescriptor > 0 {
// Run a packet tunnel client. The lifetime of the tun.Client is the
// lifetime of the Controller, so it exists across tunnel establishments
// and reestablishments. The PacketTunnelTransport provides a layer
// that presents a continuosuly existing transport to the tun.Client;
// it's set to use new SSH channels after new SSH tunnel establishes.
packetTunnelTransport := NewPacketTunnelTransport()
packetTunnelClient, err := tun.NewClient(&tun.ClientConfig{
Logger: NoticeCommonLogger(),
TunFileDescriptor: config.PacketTunnelTunFileDescriptor,
Transport: packetTunnelTransport,
})
if err != nil {
return nil, common.ContextError(err)
}
controller.packetTunnelClient = packetTunnelClient
controller.packetTunnelTransport = packetTunnelTransport
}
return controller, nil
}
// Run executes the controller. Run exits if a controller
// component fails or the parent context is canceled.
func (controller *Controller) Run(ctx context.Context) {
pprofRun()
// Ensure fresh repetitive notice state for each run, so the
// client will always get an AvailableEgressRegions notice,
// an initial instance of any repetitive error notice, etc.
ResetRepetitiveNotices()
runCtx, stopRunning := context.WithCancel(ctx)
defer stopRunning()
controller.runCtx = runCtx
controller.stopRunning = stopRunning
// Start components
// TODO: IPv6 support
var listenIP string
if controller.config.ListenInterface == "" {
listenIP = "127.0.0.1"
} else if controller.config.ListenInterface == "any" {
listenIP = "0.0.0.0"
} else {
IPv4Address, _, err := common.GetInterfaceIPAddresses(controller.config.ListenInterface)
if err == nil && IPv4Address == nil {
err = fmt.Errorf("no IPv4 address for interface %s", controller.config.ListenInterface)
}
if err != nil {
NoticeError("error getting listener IP: %s", err)
return
}
listenIP = IPv4Address.String()
}
if !controller.config.DisableLocalSocksProxy {
socksProxy, err := NewSocksProxy(controller.config, controller, listenIP)
if err != nil {
NoticeAlert("error initializing local SOCKS proxy: %s", err)
return
}
defer socksProxy.Close()
}
if !controller.config.DisableLocalHTTPProxy {
httpProxy, err := NewHttpProxy(controller.config, controller, listenIP)
if err != nil {
NoticeAlert("error initializing local HTTP proxy: %s", err)
return
}
defer httpProxy.Close()
}
if !controller.config.DisableRemoteServerListFetcher {
if controller.config.RemoteServerListURLs != nil {
controller.runWaitGroup.Add(1)
go controller.remoteServerListFetcher(
"common",
FetchCommonRemoteServerList,
controller.signalFetchCommonRemoteServerList)
}
if controller.config.ObfuscatedServerListRootURLs != nil {
controller.runWaitGroup.Add(1)
go controller.remoteServerListFetcher(
"obfuscated",
FetchObfuscatedServerLists,
controller.signalFetchObfuscatedServerLists)
}
}
if controller.config.UpgradeDownloadURLs != nil {
controller.runWaitGroup.Add(1)
go controller.upgradeDownloader()
}
/// Note: the connected reporter isn't started until a tunnel is
// established
controller.runWaitGroup.Add(1)
go controller.runTunnels()
controller.runWaitGroup.Add(1)
go controller.establishTunnelWatcher()
if controller.packetTunnelClient != nil {
controller.packetTunnelClient.Start()
}
// Wait while running
<-controller.runCtx.Done()
NoticeInfo("controller stopped")
if controller.packetTunnelClient != nil {
controller.packetTunnelClient.Stop()
}
// All workers -- runTunnels, establishment workers, and auxilliary
// workers such as fetch remote server list and untunneled uprade
// download -- operate with the controller run context and will all
// be interrupted when the run context is done.
controller.runWaitGroup.Wait()
controller.splitTunnelClassifier.Shutdown()
NoticeInfo("exiting controller")
NoticeExiting()
}
// SignalComponentFailure notifies the controller that an associated component has failed.
// This will terminate the controller.
func (controller *Controller) SignalComponentFailure() {
NoticeAlert("controller shutdown due to component failure")
controller.stopRunning()
}
// SetDynamicConfig overrides the sponsor ID and authorizations fields of the
// Controller config with the input values. The new values will be used in the
// next tunnel connection.
func (controller *Controller) SetDynamicConfig(sponsorID string, authorizations []string) {
controller.config.SetDynamicConfig(sponsorID, authorizations)
}
// TerminateNextActiveTunnel terminates the active tunnel, which will initiate
// establishment of a new tunnel.
func (controller *Controller) TerminateNextActiveTunnel() {
tunnel := controller.getNextActiveTunnel()
if tunnel != nil {
controller.SignalTunnelFailure(tunnel)
NoticeInfo("terminated tunnel: %s", tunnel.dialParams.ServerEntry.IpAddress)
}
}
// remoteServerListFetcher fetches an out-of-band list of server entries
// for more tunnel candidates. It fetches when signalled, with retries
// on failure.
func (controller *Controller) remoteServerListFetcher(
name string,
fetcher RemoteServerListFetcher,
signal <-chan struct{}) {
defer controller.runWaitGroup.Done()
var lastFetchTime monotime.Time
fetcherLoop:
for {
// Wait for a signal before fetching
select {
case <-signal:
case <-controller.runCtx.Done():
break fetcherLoop
}
// Skip fetch entirely (i.e., send no request at all, even when ETag would save
// on response size) when a recent fetch was successful
stalePeriod := controller.config.GetClientParametersSnapshot().Duration(
parameters.FetchRemoteServerListStalePeriod)
if lastFetchTime != 0 &&
lastFetchTime.Add(stalePeriod).After(monotime.Now()) {
continue
}
retryLoop:
for attempt := 0; ; attempt++ {
// Don't attempt to fetch while there is no network connectivity,
// to avoid alert notice noise.
if !WaitForNetworkConnectivity(
controller.runCtx,
controller.config.NetworkConnectivityChecker) {
break fetcherLoop
}
// Pick any active tunnel and make the next fetch attempt. If there's
// no active tunnel, the untunneledDialConfig will be used.
tunnel := controller.getNextActiveTunnel()
err := fetcher(
controller.runCtx,
controller.config,
attempt,
tunnel,
controller.untunneledDialConfig)
if err == nil {
lastFetchTime = monotime.Now()
break retryLoop
}
NoticeAlert("failed to fetch %s remote server list: %s", name, err)
retryPeriod := controller.config.GetClientParametersSnapshot().Duration(
parameters.FetchRemoteServerListRetryPeriod)
timer := time.NewTimer(retryPeriod)
select {
case <-timer.C:
case <-controller.runCtx.Done():
timer.Stop()
break fetcherLoop
}
}
}
NoticeInfo("exiting %s remote server list fetcher", name)
}
// establishTunnelWatcher terminates the controller if a tunnel
// has not been established in the configured time period. This
// is regardless of how many tunnels are presently active -- meaning
// that if an active tunnel was established and lost the controller
// is left running (to re-establish).
func (controller *Controller) establishTunnelWatcher() {
defer controller.runWaitGroup.Done()
timeout := controller.config.GetClientParametersSnapshot().Duration(
parameters.EstablishTunnelTimeout)
if timeout > 0 {
timer := time.NewTimer(timeout)
defer timer.Stop()
select {
case <-timer.C:
if !controller.hasEstablishedOnce() {
NoticeEstablishTunnelTimeout(timeout)
controller.SignalComponentFailure()
}
case <-controller.runCtx.Done():
}
}
NoticeInfo("exiting establish tunnel watcher")
}
// connectedReporter sends periodic "connected" requests to the Psiphon API.
// These requests are for server-side unique user stats calculation. See the
// comment in DoConnectedRequest for a description of the request mechanism.
// To ensure we don't over- or under-count unique users, only one connected
// request is made across all simultaneous multi-tunnels; and the connected
// request is repeated periodically for very long-lived tunnels.
// The signalReportConnected mechanism is used to trigger another connected
// request immediately after a reconnect.
func (controller *Controller) connectedReporter() {
defer controller.runWaitGroup.Done()
loop:
for {
// Pick any active tunnel and make the next connected request. No error
// is logged if there's no active tunnel, as that's not an unexpected condition.
reported := false
tunnel := controller.getNextActiveTunnel()
if tunnel != nil {
err := tunnel.serverContext.DoConnectedRequest()
if err == nil {
reported = true
} else {
NoticeAlert("failed to make connected request: %s", err)
}
}
// Schedule the next connected request and wait.
// Note: this duration is not a dynamic ClientParameter as
// the daily unique user stats logic specifically requires
// a "connected" request no more or less often than every
// 24 hours.
var duration time.Duration
if reported {
duration = 24 * time.Hour
} else {
duration = controller.config.GetClientParametersSnapshot().Duration(
parameters.PsiphonAPIConnectedRequestRetryPeriod)
}
timer := time.NewTimer(duration)
doBreak := false
select {
case <-controller.signalReportConnected:
case <-timer.C:
// Make another connected request
case <-controller.runCtx.Done():
doBreak = true
}
timer.Stop()
if doBreak {
break loop
}
}
NoticeInfo("exiting connected reporter")
}
func (controller *Controller) startOrSignalConnectedReporter() {
// session is nil when DisableApi is set
if controller.config.DisableApi {
return
}
// Start the connected reporter after the first tunnel is established.
// Concurrency note: only the runTunnels goroutine may access startedConnectedReporter.
if !controller.startedConnectedReporter {
controller.startedConnectedReporter = true
controller.runWaitGroup.Add(1)
go controller.connectedReporter()
} else {
select {
case controller.signalReportConnected <- *new(struct{}):
default:
}
}
}
// upgradeDownloader makes periodic attempts to complete a client upgrade
// download. DownloadUpgrade() is resumable, so each attempt has potential for
// getting closer to completion, even in conditions where the download or
// tunnel is repeatedly interrupted.
// An upgrade download is triggered by either a handshake response indicating
// that a new version is available; or after failing to connect, in which case
// it's useful to check, out-of-band, for an upgrade with new circumvention
// capabilities.
// Once the download operation completes successfully, the downloader exits
// and is not run again: either there is not a newer version, or the upgrade
// has been downloaded and is ready to be applied.
// We're assuming that the upgrade will be applied and the entire system
// restarted before another upgrade is to be downloaded.
//
// TODO: refactor upgrade downloader and remote server list fetcher to use
// common code (including the resumable download routines).
//
func (controller *Controller) upgradeDownloader() {
defer controller.runWaitGroup.Done()
var lastDownloadTime monotime.Time
downloadLoop:
for {
// Wait for a signal before downloading
var handshakeVersion string
select {
case handshakeVersion = <-controller.signalDownloadUpgrade:
case <-controller.runCtx.Done():
break downloadLoop
}
stalePeriod := controller.config.GetClientParametersSnapshot().Duration(
parameters.FetchUpgradeStalePeriod)
// Unless handshake is explicitly advertizing a new version, skip
// checking entirely when a recent download was successful.
if handshakeVersion == "" &&
lastDownloadTime != 0 &&
lastDownloadTime.Add(stalePeriod).After(monotime.Now()) {
continue
}
retryLoop:
for attempt := 0; ; attempt++ {
// Don't attempt to download while there is no network connectivity,
// to avoid alert notice noise.
if !WaitForNetworkConnectivity(
controller.runCtx,
controller.config.NetworkConnectivityChecker) {
break downloadLoop
}
// Pick any active tunnel and make the next download attempt. If there's
// no active tunnel, the untunneledDialConfig will be used.
tunnel := controller.getNextActiveTunnel()
err := DownloadUpgrade(
controller.runCtx,
controller.config,
attempt,
handshakeVersion,
tunnel,
controller.untunneledDialConfig)
if err == nil {
lastDownloadTime = monotime.Now()
break retryLoop
}
NoticeAlert("failed to download upgrade: %s", err)
timeout := controller.config.GetClientParametersSnapshot().Duration(
parameters.FetchUpgradeRetryPeriod)
timer := time.NewTimer(timeout)
select {
case <-timer.C:
case <-controller.runCtx.Done():
timer.Stop()
break downloadLoop
}
}
}
NoticeInfo("exiting upgrade downloader")
}
// runTunnels is the controller tunnel management main loop. It starts and stops
// establishing tunnels based on the target tunnel pool size and the current size
// of the pool. Tunnels are established asynchronously using worker goroutines.
//
// When there are no server entries for the target region/protocol, the
// establishCandidateGenerator will yield no candidates and wait before
// trying again. In the meantime, a remote server entry fetch may supply
// valid candidates.
//
// When a tunnel is established, it's added to the active pool. The tunnel's
// operateTunnel goroutine monitors the tunnel.
//
// When a tunnel fails, it's removed from the pool and the establish process is
// restarted to fill the pool.
func (controller *Controller) runTunnels() {
defer controller.runWaitGroup.Done()
// Start running
controller.startEstablishing()
loop:
for {
select {
case failedTunnel := <-controller.failedTunnels:
NoticeAlert("tunnel failed: %s", failedTunnel.dialParams.ServerEntry.IpAddress)
controller.terminateTunnel(failedTunnel)
// Clear the reference to this tunnel before calling startEstablishing,
// which will invoke a garbage collection.
failedTunnel = nil
// Concurrency note: only this goroutine may call startEstablishing/stopEstablishing,
// which reference controller.isEstablishing.
controller.startEstablishing()
case connectedTunnel := <-controller.connectedTunnels:
// Tunnel establishment has two phases: connection and activation.
//
// Connection is run concurrently by the establishTunnelWorkers, to minimize
// delay when it's not yet known which server and protocol will be available
// and unblocked.
//
// Activation is run serially, here, to minimize the overhead of making a
// handshake request and starting the operateTunnel management worker for a
// tunnel which may be discarded.
//
// When the active tunnel will complete establishment, establishment is
// stopped before activation. This interrupts all connecting tunnels and
// garbage collects their memory. The purpose is to minimize memory
// pressure when the handshake request is made. In the unlikely case that the
// handshake fails, establishment is restarted.
//
// Any delays in stopEstablishing will delay the handshake for the last
// active tunnel.
//
// In the typical case of TunnelPoolSize of 1, only a single handshake is
// performed and the homepages notices file, when used, will not be modifed
// after the NoticeTunnels(1) [i.e., connected] until NoticeTunnels(0) [i.e.,
// disconnected]. For TunnelPoolSize > 1, serial handshakes only ensures that
// each set of emitted NoticeHomepages is contiguous.
active, outstanding := controller.numTunnels()
// discardTunnel will be true here when already fully established.
discardTunnel := (outstanding <= 0)
isFirstTunnel := (active == 0)
isLastTunnel := (outstanding == 1)
if !discardTunnel {
if isLastTunnel {
controller.stopEstablishing()
}
err := connectedTunnel.Activate(controller.runCtx, controller)
if err != nil {
NoticeAlert("failed to activate %s: %s",
connectedTunnel.dialParams.ServerEntry.IpAddress, err)
discardTunnel = true
} else {
// It's unlikely that registerTunnel will fail, since only this goroutine
// calls registerTunnel -- and after checking numTunnels; so failure is not
// expected.
if !controller.registerTunnel(connectedTunnel) {
NoticeAlert("failed to register %s: %s",
connectedTunnel.dialParams.ServerEntry.IpAddress, err)
discardTunnel = true
}
}
// May need to replace this tunnel
if isLastTunnel && discardTunnel {
controller.startEstablishing()
}
}
if discardTunnel {
controller.discardTunnel(connectedTunnel)
// Clear the reference to this discarded tunnel and immediately run
// a garbage collection to reclaim its memory.
connectedTunnel = nil
DoGarbageCollection()
// Skip the rest of this case
break
}
NoticeActiveTunnel(
connectedTunnel.dialParams.ServerEntry.IpAddress,
connectedTunnel.dialParams.TunnelProtocol,
connectedTunnel.dialParams.ServerEntry.SupportsSSHAPIRequests())
if isFirstTunnel {
// The split tunnel classifier is started once the first tunnel is
// established. This first tunnel is passed in to be used to make
// the routes data request.
// A long-running controller may run while the host device is present
// in different regions. In this case, we want the split tunnel logic
// to switch to routes for new regions and not classify traffic based
// on routes installed for older regions.
// We assume that when regions change, the host network will also
// change, and so all tunnels will fail and be re-established. Under
// that assumption, the classifier will be re-Start()-ed here when
// the region has changed.
controller.splitTunnelClassifier.Start(connectedTunnel)
// Signal a connected request on each 1st tunnel establishment. For
// multi-tunnels, the session is connected as long as at least one
// tunnel is established.
controller.startOrSignalConnectedReporter()
// If the handshake indicated that a new client version is available,
// trigger an upgrade download.
// Note: serverContext is nil when DisableApi is set
if connectedTunnel.serverContext != nil &&
connectedTunnel.serverContext.clientUpgradeVersion != "" {
handshakeVersion := connectedTunnel.serverContext.clientUpgradeVersion
select {
case controller.signalDownloadUpgrade <- handshakeVersion:
default:
}
}
}
// Set the new tunnel as the transport for the packet tunnel. The packet tunnel
// client remains up when reestablishing, but no packets are relayed while there
// is no connected tunnel. UseTunnel will establish a new packet tunnel SSH
// channel over the new SSH tunnel and configure the packet tunnel client to use
// the new SSH channel as its transport.
//
// Note: as is, this logic is suboptimal for TunnelPoolSize > 1, as this would
// continuously initialize new packet tunnel sessions for each established
// server. For now, config validation requires TunnelPoolSize == 1 when
// the packet tunnel is used.
if controller.packetTunnelTransport != nil {
controller.packetTunnelTransport.UseTunnel(connectedTunnel)
}
// TODO: design issue -- might not be enough server entries with region/caps to ever fill tunnel slots;
// possible solution is establish target MIN(CountServerEntries(region, protocol), TunnelPoolSize)
if controller.isFullyEstablished() {
controller.stopEstablishing()
}
case <-controller.runCtx.Done():
break loop
}
}
// Stop running
controller.stopEstablishing()
controller.terminateAllTunnels()
// Drain tunnel channels
close(controller.connectedTunnels)
for tunnel := range controller.connectedTunnels {
controller.discardTunnel(tunnel)
}
close(controller.failedTunnels)
for tunnel := range controller.failedTunnels {
controller.discardTunnel(tunnel)
}
NoticeInfo("exiting run tunnels")
}
// SignalSeededNewSLOK implements the TunnelOwner interface. This function
// is called by Tunnel.operateTunnel when the tunnel has received a new,
// previously unknown SLOK from the server. The Controller triggers an OSL
// fetch, as the new SLOK may be sufficient to access new OSLs.
func (controller *Controller) SignalSeededNewSLOK() {
select {
case controller.signalFetchObfuscatedServerLists <- *new(struct{}):
default:
}
}
// SignalTunnelFailure implements the TunnelOwner interface. This function
// is called by Tunnel.operateTunnel when the tunnel has detected that it
// has failed. The Controller will signal runTunnels to create a new
// tunnel and/or remove the tunnel from the list of active tunnels.
func (controller *Controller) SignalTunnelFailure(tunnel *Tunnel) {
// Don't block. Assumes the receiver has a buffer large enough for
// the typical number of operated tunnels. In case there's no room,
// terminate the tunnel (runTunnels won't get a signal in this case,
// but the tunnel will be removed from the list of active tunnels).
select {
case controller.failedTunnels <- tunnel:
default:
controller.terminateTunnel(tunnel)
}
}
// discardTunnel disposes of a successful connection that is no longer required.
func (controller *Controller) discardTunnel(tunnel *Tunnel) {
NoticeInfo("discard tunnel: %s", tunnel.dialParams.ServerEntry.IpAddress)
// TODO: not calling PromoteServerEntry, since that would rank the
// discarded tunnel before fully active tunnels. Can a discarded tunnel
// be promoted (since it connects), but with lower rank than all active
// tunnels?
tunnel.Close(true)
}
// registerTunnel adds the connected tunnel to the pool of active tunnels
// which are candidates for port forwarding. Returns true if the pool has an
// empty slot and false if the pool is full (caller should discard the tunnel).
func (controller *Controller) registerTunnel(tunnel *Tunnel) bool {
controller.tunnelMutex.Lock()
defer controller.tunnelMutex.Unlock()
if len(controller.tunnels) >= controller.config.TunnelPoolSize {
return false
}
// Perform a final check just in case we've established
// a duplicate connection.
for _, activeTunnel := range controller.tunnels {
if activeTunnel.dialParams.ServerEntry.IpAddress ==
tunnel.dialParams.ServerEntry.IpAddress {
NoticeAlert("duplicate tunnel: %s", tunnel.dialParams.ServerEntry.IpAddress)
return false
}
}
controller.establishedOnce = true
controller.tunnels = append(controller.tunnels, tunnel)
NoticeTunnels(len(controller.tunnels))
// Promote this successful tunnel to first rank so it's one
// of the first candidates next time establish runs.
// Connecting to a TargetServerEntry does not change the
// ranking.
if controller.config.TargetServerEntry == "" {
PromoteServerEntry(controller.config, tunnel.dialParams.ServerEntry.IpAddress)
}
return true
}
// hasEstablishedOnce indicates if at least one active tunnel has
// been established up to this point. This is regardeless of how many
// tunnels are presently active.
func (controller *Controller) hasEstablishedOnce() bool {
controller.tunnelMutex.Lock()
defer controller.tunnelMutex.Unlock()
return controller.establishedOnce
}
// isFullyEstablished indicates if the pool of active tunnels is full.
func (controller *Controller) isFullyEstablished() bool {
controller.tunnelMutex.Lock()
defer controller.tunnelMutex.Unlock()
return len(controller.tunnels) >= controller.config.TunnelPoolSize
}
// numTunnels returns the number of active and outstanding tunnels.
// Oustanding is the number of tunnels required to fill the pool of
// active tunnels.
func (controller *Controller) numTunnels() (int, int) {
controller.tunnelMutex.Lock()
defer controller.tunnelMutex.Unlock()
active := len(controller.tunnels)
outstanding := controller.config.TunnelPoolSize - len(controller.tunnels)
return active, outstanding
}
// terminateTunnel removes a tunnel from the pool of active tunnels
// and closes the tunnel. The next-tunnel state used by getNextActiveTunnel
// is adjusted as required.
func (controller *Controller) terminateTunnel(tunnel *Tunnel) {
controller.tunnelMutex.Lock()
defer controller.tunnelMutex.Unlock()
for index, activeTunnel := range controller.tunnels {
if tunnel == activeTunnel {
controller.tunnels = append(
controller.tunnels[:index], controller.tunnels[index+1:]...)
if controller.nextTunnel > index {
controller.nextTunnel--
}
if controller.nextTunnel >= len(controller.tunnels) {
controller.nextTunnel = 0
}
activeTunnel.Close(false)
NoticeTunnels(len(controller.tunnels))
break
}
}
}
// terminateAllTunnels empties the tunnel pool, closing all active tunnels.
// This is used when shutting down the controller.
func (controller *Controller) terminateAllTunnels() {
controller.tunnelMutex.Lock()
defer controller.tunnelMutex.Unlock()
// Closing all tunnels in parallel. In an orderly shutdown, each tunnel
// may take a few seconds to send a final status request. We only want
// to wait as long as the single slowest tunnel.
closeWaitGroup := new(sync.WaitGroup)
closeWaitGroup.Add(len(controller.tunnels))
for _, activeTunnel := range controller.tunnels {
tunnel := activeTunnel
go func() {
defer closeWaitGroup.Done()
tunnel.Close(false)
}()
}
closeWaitGroup.Wait()
controller.tunnels = make([]*Tunnel, 0)
controller.nextTunnel = 0
NoticeTunnels(len(controller.tunnels))
}
// getNextActiveTunnel returns the next tunnel from the pool of active
// tunnels. Currently, tunnel selection order is simple round-robin.
func (controller *Controller) getNextActiveTunnel() (tunnel *Tunnel) {
controller.tunnelMutex.Lock()
defer controller.tunnelMutex.Unlock()
for i := len(controller.tunnels); i > 0; i-- {
tunnel = controller.tunnels[controller.nextTunnel]
controller.nextTunnel =
(controller.nextTunnel + 1) % len(controller.tunnels)
return tunnel
}
return nil
}
// isActiveTunnelServerEntry is used to check if there's already
// an existing tunnel to a candidate server.
func (controller *Controller) isActiveTunnelServerEntry(
serverEntry *protocol.ServerEntry) bool {
controller.tunnelMutex.Lock()
defer controller.tunnelMutex.Unlock()
for _, activeTunnel := range controller.tunnels {
if activeTunnel.dialParams.ServerEntry.IpAddress == serverEntry.IpAddress {
return true
}
}
return false
}
// Dial selects an active tunnel and establishes a port forward
// connection through the selected tunnel. Failure to connect is considered
// a port forward failure, for the purpose of monitoring tunnel health.
func (controller *Controller) Dial(
remoteAddr string, alwaysTunnel bool, downstreamConn net.Conn) (conn net.Conn, err error) {
tunnel := controller.getNextActiveTunnel()
if tunnel == nil {
return nil, common.ContextError(errors.New("no active tunnels"))
}
// Perform split tunnel classification when feature is enabled, and if the remote
// address is classified as untunneled, dial directly.
if !alwaysTunnel && controller.config.SplitTunnelDNSServer != "" {
host, _, err := net.SplitHostPort(remoteAddr)
if err != nil {
return nil, common.ContextError(err)
}
// Note: a possible optimization, when split tunnel is active and IsUntunneled performs
// a DNS resolution in order to make its classification, is to reuse that IP address in
// the following Dials so they do not need to make their own resolutions. However, the
// way this is currently implemented ensures that, e.g., DNS geo load balancing occurs
// relative to the outbound network.
if controller.splitTunnelClassifier.IsUntunneled(host) {
return controller.DirectDial(remoteAddr)
}
}
tunneledConn, err := tunnel.Dial(remoteAddr, alwaysTunnel, downstreamConn)
if err != nil {
return nil, common.ContextError(err)
}
return tunneledConn, nil
}
// DirectDial dials an untunneled TCP connection within the controller run context.
func (controller *Controller) DirectDial(remoteAddr string) (conn net.Conn, err error) {
return DialTCP(controller.runCtx, remoteAddr, controller.untunneledDialConfig)
}
// triggerFetches signals RSL, OSL, and upgrade download fetchers to begin, if
// not already running. triggerFetches is called when tunnel establishment
// fails to complete within a deadline and in other cases where local
// circumvention capabilities are lacking and we may require new server
// entries or client versions with new capabilities.
func (controller *Controller) triggerFetches() {
// Trigger a common remote server list fetch, since we may have failed
// to connect with all known servers. Don't block sending signal, since
// this signal may have already been sent.
// Don't wait for fetch remote to succeed, since it may fail and
// enter a retry loop and we're better off trying more known servers.
// TODO: synchronize the fetch response, so it can be incorporated
// into the server entry iterator as soon as available.
select {
case controller.signalFetchCommonRemoteServerList <- *new(struct{}):
default:
}
// Trigger an OSL fetch in parallel. Both fetches are run in parallel
// so that if one out of the common RLS and OSL set is large, it doesn't
// doesn't entirely block fetching the other.
select {
case controller.signalFetchObfuscatedServerLists <- *new(struct{}):
default:
}