tailscale/health/health.go

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// Copyright (c) 2021 Tailscale Inc & AUTHORS All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package health is a registry for other packages to report & check
// overall health status of the node.
package health
import (
"errors"
"fmt"
"net/http"
"runtime"
"sort"
"sync"
"sync/atomic"
"time"
"tailscale.com/envknob"
"tailscale.com/tailcfg"
"tailscale.com/util/multierr"
)
var (
// mu guards everything in this var block.
mu sync.Mutex
sysErr = map[Subsystem]error{} // error key => err (or nil for no error)
watchers = map[*watchHandle]func(Subsystem, error){} // opt func to run if error state changes
timer *time.Timer
debugHandler = map[string]http.Handler{}
inMapPoll bool
inMapPollSince time.Time
lastMapPollEndedAt time.Time
lastStreamedMapResponse time.Time
derpHomeRegion int
derpRegionConnected = map[int]bool{}
derpRegionHealthProblem = map[int]string{}
derpRegionLastFrame = map[int]time.Time{}
lastMapRequestHeard time.Time // time we got a 200 from control for a MapRequest
ipnState string
ipnWantRunning bool
anyInterfaceUp = true // until told otherwise
udp4Unbound bool
controlHealth []string
lastLoginErr error
)
// Subsystem is the name of a subsystem whose health can be monitored.
type Subsystem string
const (
// SysOverall is the name representing the overall health of
// the system, rather than one particular subsystem.
SysOverall = Subsystem("overall")
// SysRouter is the name of the wgengine/router subsystem.
SysRouter = Subsystem("router")
// SysDNS is the name of the net/dns subsystem.
SysDNS = Subsystem("dns")
// SysDNSOS is the name of the net/dns OSConfigurator subsystem.
SysDNSOS = Subsystem("dns-os")
// SysDNSManager is the name of the net/dns manager subsystem.
SysDNSManager = Subsystem("dns-manager")
// SysNetworkCategory is the name of the subsystem that sets
// the Windows network adapter's "category" (public, private, domain).
// If it's unhealthy, the Windows firewall rules won't match.
SysNetworkCategory = Subsystem("network-category")
)
type watchHandle byte
// RegisterWatcher adds a function that will be called if an
// error changes state either to unhealthy or from unhealthy. It is
// not called on transition from unknown to healthy. It must be non-nil
// and is run in its own goroutine. The returned func unregisters it.
func RegisterWatcher(cb func(key Subsystem, err error)) (unregister func()) {
mu.Lock()
defer mu.Unlock()
handle := new(watchHandle)
watchers[handle] = cb
if timer == nil {
timer = time.AfterFunc(time.Minute, timerSelfCheck)
}
return func() {
mu.Lock()
defer mu.Unlock()
delete(watchers, handle)
if len(watchers) == 0 && timer != nil {
timer.Stop()
timer = nil
}
}
}
// SetRouterHealth sets the state of the wgengine/router.Router.
func SetRouterHealth(err error) { set(SysRouter, err) }
// RouterHealth returns the wgengine/router.Router error state.
func RouterHealth() error { return get(SysRouter) }
// SetDNSHealth sets the state of the net/dns.Manager
func SetDNSHealth(err error) { set(SysDNS, err) }
// DNSHealth returns the net/dns.Manager error state.
func DNSHealth() error { return get(SysDNS) }
// SetDNSOSHealth sets the state of the net/dns.OSConfigurator
func SetDNSOSHealth(err error) { set(SysDNSOS, err) }
// SetDNSManagerHealth sets the state of the Linux net/dns manager's
// discovery of the /etc/resolv.conf situation.
func SetDNSManagerHealth(err error) { set(SysDNSManager, err) }
// DNSOSHealth returns the net/dns.OSConfigurator error state.
func DNSOSHealth() error { return get(SysDNSOS) }
// SetNetworkCategoryHealth sets the state of setting the network adaptor's category.
// This only applies on Windows.
func SetNetworkCategoryHealth(err error) { set(SysNetworkCategory, err) }
func NetworkCategoryHealth() error { return get(SysNetworkCategory) }
func RegisterDebugHandler(typ string, h http.Handler) {
mu.Lock()
defer mu.Unlock()
debugHandler[typ] = h
}
func DebugHandler(typ string) http.Handler {
mu.Lock()
defer mu.Unlock()
return debugHandler[typ]
}
func get(key Subsystem) error {
mu.Lock()
defer mu.Unlock()
return sysErr[key]
}
func set(key Subsystem, err error) {
mu.Lock()
defer mu.Unlock()
setLocked(key, err)
}
func setLocked(key Subsystem, err error) {
old, ok := sysErr[key]
if !ok && err == nil {
// Initial happy path.
sysErr[key] = nil
selfCheckLocked()
return
}
if ok && (old == nil) == (err == nil) {
// No change in overall error status (nil-vs-not), so
// don't run callbacks, but exact error might've
// changed, so note it.
if err != nil {
sysErr[key] = err
}
return
}
sysErr[key] = err
selfCheckLocked()
for _, cb := range watchers {
go cb(key, err)
}
}
func SetControlHealth(problems []string) {
mu.Lock()
defer mu.Unlock()
controlHealth = problems
selfCheckLocked()
}
// GotStreamedMapResponse notes that we got a tailcfg.MapResponse
// message in streaming mode, even if it's just a keep-alive message.
func GotStreamedMapResponse() {
mu.Lock()
defer mu.Unlock()
lastStreamedMapResponse = time.Now()
selfCheckLocked()
}
// SetInPollNetMap records whether the client has an open
// HTTP long poll open to the control plane.
func SetInPollNetMap(v bool) {
mu.Lock()
defer mu.Unlock()
if v == inMapPoll {
return
}
inMapPoll = v
if v {
inMapPollSince = time.Now()
} else {
lastMapPollEndedAt = time.Now()
}
}
// GetInPollNetMap reports whether the client has an open
// HTTP long poll open to the control plane.
func GetInPollNetMap() bool {
mu.Lock()
defer mu.Unlock()
return inMapPoll
}
// SetMagicSockDERPHome notes what magicsock's view of its home DERP is.
func SetMagicSockDERPHome(region int) {
mu.Lock()
defer mu.Unlock()
derpHomeRegion = region
selfCheckLocked()
}
// NoteMapRequestHeard notes whenever we successfully sent a map request
// to control for which we received a 200 response.
func NoteMapRequestHeard(mr *tailcfg.MapRequest) {
mu.Lock()
defer mu.Unlock()
// TODO: extract mr.HostInfo.NetInfo.PreferredDERP, compare
// against SetMagicSockDERPHome and
// SetDERPRegionConnectedState
lastMapRequestHeard = time.Now()
selfCheckLocked()
}
func SetDERPRegionConnectedState(region int, connected bool) {
mu.Lock()
defer mu.Unlock()
derpRegionConnected[region] = connected
selfCheckLocked()
}
// SetDERPRegionHealth sets or clears any problem associated with the
// provided DERP region.
func SetDERPRegionHealth(region int, problem string) {
mu.Lock()
defer mu.Unlock()
if problem == "" {
delete(derpRegionHealthProblem, region)
} else {
derpRegionHealthProblem[region] = problem
}
selfCheckLocked()
}
func NoteDERPRegionReceivedFrame(region int) {
mu.Lock()
defer mu.Unlock()
derpRegionLastFrame[region] = time.Now()
selfCheckLocked()
}
// state is an ipn.State.String() value: "Running", "Stopped", "NeedsLogin", etc.
func SetIPNState(state string, wantRunning bool) {
mu.Lock()
defer mu.Unlock()
ipnState = state
ipnWantRunning = wantRunning
selfCheckLocked()
}
// SetAnyInterfaceUp sets whether any network interface is up.
func SetAnyInterfaceUp(up bool) {
mu.Lock()
defer mu.Unlock()
anyInterfaceUp = up
selfCheckLocked()
}
// SetUDP4Unbound sets whether the udp4 bind failed completely.
func SetUDP4Unbound(unbound bool) {
mu.Lock()
defer mu.Unlock()
udp4Unbound = unbound
selfCheckLocked()
}
// SetAuthRoutineInError records the latest error encountered as a result of a
// login attempt. Providing a nil error indicates successful login, or that
// being logged in w/coordination is not currently desired.
func SetAuthRoutineInError(err error) {
mu.Lock()
defer mu.Unlock()
lastLoginErr = err
}
func timerSelfCheck() {
mu.Lock()
defer mu.Unlock()
checkReceiveFuncs()
selfCheckLocked()
if timer != nil {
timer.Reset(time.Minute)
}
}
func selfCheckLocked() {
if ipnState == "" {
// Don't check yet.
return
}
setLocked(SysOverall, overallErrorLocked())
}
// OverallError returns a summary of the health state.
//
// If there are multiple problems, the error will be of type
// multierr.Error.
func OverallError() error {
mu.Lock()
defer mu.Unlock()
return overallErrorLocked()
}
var fakeErrForTesting = envknob.String("TS_DEBUG_FAKE_HEALTH_ERROR")
func overallErrorLocked() error {
if !anyInterfaceUp {
return errors.New("network down")
}
if !ipnWantRunning {
return fmt.Errorf("state=%v, wantRunning=%v", ipnState, ipnWantRunning)
}
if lastLoginErr != nil {
return fmt.Errorf("not logged in, last login error=%v", lastLoginErr)
}
now := time.Now()
if !inMapPoll && (lastMapPollEndedAt.IsZero() || now.Sub(lastMapPollEndedAt) > 10*time.Second) {
return errors.New("not in map poll")
}
const tooIdle = 2*time.Minute + 5*time.Second
if d := now.Sub(lastStreamedMapResponse).Round(time.Second); d > tooIdle {
return fmt.Errorf("no map response in %v", d)
}
rid := derpHomeRegion
if rid == 0 {
return errors.New("no DERP home")
}
if !derpRegionConnected[rid] {
return fmt.Errorf("not connected to home DERP region %v", rid)
}
if d := now.Sub(derpRegionLastFrame[rid]).Round(time.Second); d > tooIdle {
return fmt.Errorf("haven't heard from home DERP region %v in %v", rid, d)
}
if udp4Unbound {
return errors.New("no udp4 bind")
}
// TODO: use
_ = inMapPollSince
_ = lastMapPollEndedAt
_ = lastStreamedMapResponse
_ = lastMapRequestHeard
var errs []error
for _, recv := range receiveFuncs {
if recv.missing {
errs = append(errs, fmt.Errorf("%s is not running", recv.name))
}
}
for sys, err := range sysErr {
if err == nil || sys == SysOverall {
continue
}
errs = append(errs, fmt.Errorf("%v: %w", sys, err))
}
for regionID, problem := range derpRegionHealthProblem {
errs = append(errs, fmt.Errorf("derp%d: %v", regionID, problem))
}
for _, s := range controlHealth {
errs = append(errs, errors.New(s))
}
if e := fakeErrForTesting; len(errs) == 0 && e != "" {
return errors.New(e)
}
sort.Slice(errs, func(i, j int) bool {
// Not super efficient (stringifying these in a sort), but probably max 2 or 3 items.
return errs[i].Error() < errs[j].Error()
})
return multierr.New(errs...)
}
var (
ReceiveIPv4 = ReceiveFuncStats{name: "ReceiveIPv4"}
ReceiveIPv6 = ReceiveFuncStats{name: "ReceiveIPv6"}
ReceiveDERP = ReceiveFuncStats{name: "ReceiveDERP"}
receiveFuncs = []*ReceiveFuncStats{&ReceiveIPv4, &ReceiveIPv6, &ReceiveDERP}
)
func init() {
if runtime.GOOS == "js" {
receiveFuncs = receiveFuncs[2:] // ignore IPv4 and IPv6
}
}
// ReceiveFuncStats tracks the calls made to a wireguard-go receive func.
type ReceiveFuncStats struct {
// name is the name of the receive func.
name string
// numCalls is the number of times the receive func has ever been called.
// It is required because it is possible for a receive func's wireguard-go goroutine
// to be active even though the receive func isn't.
// The wireguard-go goroutine alternates between calling the receive func and
// processing what the func returned.
numCalls uint64 // accessed atomically
// prevNumCalls is the value of numCalls last time the health check examined it.
prevNumCalls uint64
// inCall indicates whether the receive func is currently running.
inCall uint32 // bool, accessed atomically
// missing indicates whether the receive func is not running.
missing bool
}
func (s *ReceiveFuncStats) Enter() {
atomic.AddUint64(&s.numCalls, 1)
atomic.StoreUint32(&s.inCall, 1)
}
func (s *ReceiveFuncStats) Exit() {
atomic.StoreUint32(&s.inCall, 0)
}
func checkReceiveFuncs() {
for _, recv := range receiveFuncs {
recv.missing = false
prev := recv.prevNumCalls
numCalls := atomic.LoadUint64(&recv.numCalls)
recv.prevNumCalls = numCalls
if numCalls > prev {
// OK: the function has gotten called since last we checked
continue
}
if atomic.LoadUint32(&recv.inCall) == 1 {
// OK: the function is active, probably blocked due to inactivity
continue
}
// Not OK: The function is not active, and not accumulating new calls.
// It is probably MIA.
recv.missing = true
}
}