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https://github.com/octoleo/syncthing.git
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lib/connections: Refactor connection loop (#7177)
This breaks out some methods from the connection loop to make it simpler to manage and understand. Some slight simplifications to remove the `seen` variable (we can filter `nextDial` based on times are in the future or not, so we don't need to track `seen`) and adding a minimum loop interval (5s) in case some dialer goes haywire and requests a 0s redial interval or such. Otherwise no significant behavioral changes.
This commit is contained in:
Jakob Borg
GitHub
parent
a744dee94c
commit
05f25e600e
@ -10,6 +10,7 @@ import (
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"context"
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"crypto/tls"
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"fmt"
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"math"
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"net"
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"net/url"
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"sort"
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@ -56,6 +57,9 @@ const (
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perDeviceWarningIntv = 15 * time.Minute
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tlsHandshakeTimeout = 10 * time.Second
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minConnectionReplaceAge = 10 * time.Second
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minConnectionLoopSleep = 5 * time.Second
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stdConnectionLoopSleep = time.Minute
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worstDialerPriority = math.MaxInt32
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)
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// From go/src/crypto/tls/cipher_suites.go
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@ -342,159 +346,52 @@ func (s *service) handle(ctx context.Context) error {
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}
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func (s *service) connect(ctx context.Context) error {
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nextDial := make(map[string]time.Time)
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// Map of when to earliest dial each given device + address again
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nextDialAt := make(map[string]time.Time)
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// Used as delay for the first few connection attempts, increases
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// exponentially
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// Used as delay for the first few connection attempts (adjusted up to
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// minConnectionLoopSleep), increased exponentially until it reaches
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// stdConnectionLoopSleep, at which time the normal sleep mechanism
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// kicks in.
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initialRampup := time.Second
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// Calculated from actual dialers reconnectInterval
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var sleep time.Duration
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for {
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cfg := s.cfg.RawCopy()
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bestDialerPriority := s.bestDialerPriority(cfg)
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isInitialRampup := initialRampup < stdConnectionLoopSleep
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bestDialerPrio := 1<<31 - 1 // worse prio won't build on 32 bit
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for _, df := range dialers {
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if df.Valid(cfg) != nil {
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continue
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}
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if prio := df.Priority(); prio < bestDialerPrio {
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bestDialerPrio = prio
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}
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l.Debugln("Connection loop")
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if isInitialRampup {
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l.Debugln("Connection loop in initial rampup")
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}
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l.Debugln("Reconnect loop")
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// Used for consistency throughout this loop run, as time passes
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// while we try connections etc.
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now := time.Now()
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var seen []string
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for _, deviceCfg := range cfg.Devices {
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select {
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case <-ctx.Done():
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return ctx.Err()
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default:
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}
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// Attempt to dial all devices that are unconnected or can be connection-upgraded
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s.dialDevices(ctx, now, cfg, bestDialerPriority, nextDialAt, isInitialRampup)
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deviceID := deviceCfg.DeviceID
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if deviceID == s.myID {
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continue
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}
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if deviceCfg.Paused {
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continue
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}
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ct, connected := s.model.Connection(deviceID)
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if connected && ct.Priority() == bestDialerPrio {
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// Things are already as good as they can get.
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continue
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}
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var addrs []string
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for _, addr := range deviceCfg.Addresses {
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if addr == "dynamic" {
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if s.discoverer != nil {
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if t, err := s.discoverer.Lookup(ctx, deviceID); err == nil {
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addrs = append(addrs, t...)
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}
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}
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} else {
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addrs = append(addrs, addr)
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}
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}
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addrs = util.UniqueTrimmedStrings(addrs)
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l.Debugln("Reconnect loop for", deviceID, addrs)
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dialTargets := make([]dialTarget, 0)
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for _, addr := range addrs {
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// Use a special key that is more than just the address, as you might have two devices connected to the same relay
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nextDialKey := deviceID.String() + "/" + addr
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seen = append(seen, nextDialKey)
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nextDialAt, ok := nextDial[nextDialKey]
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if ok && initialRampup >= sleep && nextDialAt.After(now) {
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l.Debugf("Not dialing %s via %v as sleep is %v, next dial is at %s and current time is %s", deviceID, addr, sleep, nextDialAt, now)
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continue
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}
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// If we fail at any step before actually getting the dialer
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// retry in a minute
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nextDial[nextDialKey] = now.Add(time.Minute)
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uri, err := url.Parse(addr)
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if err != nil {
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s.setConnectionStatus(addr, err)
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l.Infof("Parsing dialer address %s: %v", addr, err)
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continue
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}
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if len(deviceCfg.AllowedNetworks) > 0 {
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if !IsAllowedNetwork(uri.Host, deviceCfg.AllowedNetworks) {
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s.setConnectionStatus(addr, errors.New("network disallowed"))
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l.Debugln("Network for", uri, "is disallowed")
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continue
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}
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}
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dialerFactory, err := getDialerFactory(cfg, uri)
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if err != nil {
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s.setConnectionStatus(addr, err)
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}
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if errors.Is(err, errUnsupported) {
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l.Debugf("Dialer for %v: %v", uri, err)
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continue
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} else if err != nil {
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l.Infof("Dialer for %v: %v", uri, err)
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continue
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}
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priority := dialerFactory.Priority()
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if connected && priority >= ct.Priority() {
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l.Debugf("Not dialing using %s as priority is less than current connection (%d >= %d)", dialerFactory, dialerFactory.Priority(), ct.Priority())
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continue
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}
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dialer := dialerFactory.New(s.cfg.Options(), s.tlsCfg)
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nextDial[nextDialKey] = now.Add(dialer.RedialFrequency())
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// For LAN addresses, increase the priority so that we
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// try these first.
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switch {
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case dialerFactory.AlwaysWAN():
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// Do nothing.
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case s.isLANHost(uri.Host):
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priority -= 1
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}
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dialTargets = append(dialTargets, dialTarget{
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addr: addr,
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dialer: dialer,
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priority: priority,
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deviceID: deviceID,
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uri: uri,
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})
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}
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conn, ok := s.dialParallel(ctx, deviceCfg.DeviceID, dialTargets)
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if ok {
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s.conns <- conn
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}
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}
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nextDial, sleep = filterAndFindSleepDuration(nextDial, seen, now)
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if initialRampup < sleep {
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l.Debugln("initial rampup; sleep", initialRampup, "and update to", initialRampup*2)
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var sleep time.Duration
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if isInitialRampup {
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// We are in the initial rampup time, so we slowly, statically
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// increase the sleep time.
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sleep = initialRampup
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initialRampup *= 2
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} else {
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l.Debugln("sleep until next dial", sleep)
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// The sleep time is until the next dial scheduled in nextDialAt,
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// clamped by stdConnectionLoopSleep as we don't want to sleep too
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// long (config changes might happen).
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sleep = filterAndFindSleepDuration(nextDialAt, now)
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}
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// ... while making sure not to loop too quickly either.
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if sleep < minConnectionLoopSleep {
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sleep = minConnectionLoopSleep
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}
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l.Debugln("Next connection loop in", sleep)
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select {
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case <-time.After(sleep):
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case <-ctx.Done():
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@ -503,6 +400,145 @@ func (s *service) connect(ctx context.Context) error {
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}
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}
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func (s *service) bestDialerPriority(cfg config.Configuration) int {
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bestDialerPriority := worstDialerPriority
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for _, df := range dialers {
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if df.Valid(cfg) != nil {
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continue
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}
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if prio := df.Priority(); prio < bestDialerPriority {
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bestDialerPriority = prio
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}
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}
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return bestDialerPriority
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}
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func (s *service) dialDevices(ctx context.Context, now time.Time, cfg config.Configuration, bestDialerPriority int, nextDialAt map[string]time.Time, initial bool) {
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for _, deviceCfg := range cfg.Devices {
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// Don't attempt to connect to ourselves...
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if deviceCfg.DeviceID == s.myID {
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continue
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}
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// Don't attempt to connect to paused devices...
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if deviceCfg.Paused {
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continue
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}
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// See if we are already connected and, if so, what our cutoff is
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// for dialer priority.
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priorityCutoff := worstDialerPriority
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connection, connected := s.model.Connection(deviceCfg.DeviceID)
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if connected {
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priorityCutoff = connection.Priority()
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if bestDialerPriority >= priorityCutoff {
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// Our best dialer is not any better than what we already
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// have, so nothing to do here.
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continue
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}
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}
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dialTargets := s.resolveDialTargets(ctx, now, cfg, deviceCfg, nextDialAt, initial, priorityCutoff)
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if conn, ok := s.dialParallel(ctx, deviceCfg.DeviceID, dialTargets); ok {
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s.conns <- conn
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}
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}
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}
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func (s *service) resolveDialTargets(ctx context.Context, now time.Time, cfg config.Configuration, deviceCfg config.DeviceConfiguration, nextDialAt map[string]time.Time, initial bool, priorityCutoff int) []dialTarget {
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deviceID := deviceCfg.DeviceID
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addrs := s.resolveDeviceAddrs(ctx, deviceCfg)
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l.Debugln("Resolved device", deviceID, "addresses:", addrs)
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dialTargets := make([]dialTarget, 0, len(addrs))
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for _, addr := range addrs {
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// Use a special key that is more than just the address, as you
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// might have two devices connected to the same relay
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nextDialKey := deviceID.String() + "/" + addr
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when, ok := nextDialAt[nextDialKey]
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if ok && !initial && when.After(now) {
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l.Debugf("Not dialing %s via %v as it's not time yet", deviceID, addr)
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continue
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}
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// If we fail at any step before actually getting the dialer
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// retry in a minute
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nextDialAt[nextDialKey] = now.Add(time.Minute)
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uri, err := url.Parse(addr)
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if err != nil {
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s.setConnectionStatus(addr, err)
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l.Infof("Parsing dialer address %s: %v", addr, err)
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continue
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}
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if len(deviceCfg.AllowedNetworks) > 0 {
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if !IsAllowedNetwork(uri.Host, deviceCfg.AllowedNetworks) {
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s.setConnectionStatus(addr, errors.New("network disallowed"))
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l.Debugln("Network for", uri, "is disallowed")
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continue
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}
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}
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dialerFactory, err := getDialerFactory(cfg, uri)
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if err != nil {
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s.setConnectionStatus(addr, err)
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}
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if errors.Is(err, errUnsupported) {
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l.Debugf("Dialer for %v: %v", uri, err)
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continue
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} else if err != nil {
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l.Infof("Dialer for %v: %v", uri, err)
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continue
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}
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priority := dialerFactory.Priority()
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if priority >= priorityCutoff {
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l.Debugf("Not dialing using %s as priority is not better than current connection (%d >= %d)", dialerFactory, dialerFactory.Priority(), priorityCutoff)
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continue
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}
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dialer := dialerFactory.New(s.cfg.Options(), s.tlsCfg)
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nextDialAt[nextDialKey] = now.Add(dialer.RedialFrequency())
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// For LAN addresses, increase the priority so that we
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// try these first.
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switch {
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case dialerFactory.AlwaysWAN():
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// Do nothing.
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case s.isLANHost(uri.Host):
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priority--
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}
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dialTargets = append(dialTargets, dialTarget{
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addr: addr,
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dialer: dialer,
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priority: priority,
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deviceID: deviceID,
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uri: uri,
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})
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}
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return dialTargets
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}
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func (s *service) resolveDeviceAddrs(ctx context.Context, cfg config.DeviceConfiguration) []string {
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var addrs []string
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for _, addr := range cfg.Addresses {
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if addr == "dynamic" {
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if s.discoverer != nil {
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if t, err := s.discoverer.Lookup(ctx, cfg.DeviceID); err == nil {
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addrs = append(addrs, t...)
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}
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}
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} else {
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addrs = append(addrs, addr)
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}
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}
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return util.UniqueTrimmedStrings(addrs)
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}
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func (s *service) isLANHost(host string) bool {
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// Probably we are called with an ip:port combo which we can resolve as
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// a TCP address.
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@ -778,24 +814,19 @@ func getListenerFactory(cfg config.Configuration, uri *url.URL) (listenerFactory
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return listenerFactory, nil
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}
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func filterAndFindSleepDuration(nextDial map[string]time.Time, seen []string, now time.Time) (map[string]time.Time, time.Duration) {
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newNextDial := make(map[string]time.Time)
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for _, addr := range seen {
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nextDialAt, ok := nextDial[addr]
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if ok {
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newNextDial[addr] = nextDialAt
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func filterAndFindSleepDuration(nextDialAt map[string]time.Time, now time.Time) time.Duration {
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sleep := stdConnectionLoopSleep
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for key, next := range nextDialAt {
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if next.Before(now) {
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// Expired entry, address was not seen in last pass(es)
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delete(nextDialAt, key)
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continue
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}
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if cur := next.Sub(now); cur < sleep {
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sleep = cur
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}
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}
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min := time.Minute
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for _, next := range newNextDial {
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cur := next.Sub(now)
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if cur < min {
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min = cur
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}
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}
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return newNextDial, min
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return sleep
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}
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func urlsToStrings(urls []*url.URL) []string {
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