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tailscale/ipn/local.go

718 lines
17 KiB
Go

// Copyright (c) 2020 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 ipn
import (
"errors"
"fmt"
"log"
"strings"
"sync"
"time"
"github.com/tailscale/wireguard-go/wgcfg"
"tailscale.com/control/controlclient"
"tailscale.com/portlist"
"tailscale.com/tailcfg"
"tailscale.com/types/empty"
"tailscale.com/types/logger"
"tailscale.com/version"
"tailscale.com/wgengine"
"tailscale.com/wgengine/filter"
)
// LocalBackend is the scaffolding between the Tailscale cloud control
// plane and the local network stack.
type LocalBackend struct {
logf logger.Logf
notify func(n Notify)
c *controlclient.Client
e wgengine.Engine
store StateStore
serverURL string
backendLogID string
portpoll *portlist.Poller // may be nil
newDecompressor func() (controlclient.Decompressor, error)
cmpDiff func(x, y interface{}) string
// The mutex protects the following elements.
mu sync.Mutex
stateKey StateKey
prefs Prefs
state State
hiCache tailcfg.Hostinfo
netMapCache *controlclient.NetworkMap
engineStatus EngineStatus
endPoints []string
blocked bool
authURL string
interact int
// statusLock must be held before calling statusChanged.Lock() or
// statusChanged.Broadcast().
statusLock sync.Mutex
statusChanged *sync.Cond
}
// NewLocalBackend returns a new LocalBackend that is ready to run,
// but is not actually running.
func NewLocalBackend(logf logger.Logf, logid string, store StateStore, e wgengine.Engine) (*LocalBackend, error) {
if e == nil {
panic("ipn.NewLocalBackend: wgengine must not be nil")
}
// Default filter blocks everything, until Start() is called.
e.SetFilter(filter.NewAllowNone())
portpoll, err := portlist.NewPoller()
if err != nil {
logf("skipping portlist: %s\n", err)
}
b := LocalBackend{
logf: logf,
e: e,
store: store,
backendLogID: logid,
state: NoState,
portpoll: portpoll,
}
b.statusChanged = sync.NewCond(&b.statusLock)
if b.portpoll != nil {
go b.portpoll.Run()
go b.runPoller()
}
return &b, nil
}
func (b *LocalBackend) Shutdown() {
if b.portpoll != nil {
b.portpoll.Close()
}
b.c.Shutdown()
b.e.Close()
b.e.Wait()
}
// SetDecompressor sets a decompression function, which must be a zstd
// reader.
//
// This exists because the iOS/Mac NetworkExtension is very resource
// constrained, and the zstd package is too heavy to fit in the
// constrained RSS limit.
func (b *LocalBackend) SetDecompressor(fn func() (controlclient.Decompressor, error)) {
b.newDecompressor = fn
}
// SetCmpDiff sets a comparison function used to generate logs of what
// has changed in the network map.
//
// Typically the comparison function comes from go-cmp.
// We don't wire it in directly here because the go-cmp package adds
// 1.77mb to the binary size of the iOS NetworkExtension, which takes
// away from its precious RSS limit.
func (b *LocalBackend) SetCmpDiff(cmpDiff func(x, y interface{}) string) {
b.cmpDiff = cmpDiff
}
func (b *LocalBackend) Start(opts Options) error {
if opts.Prefs == nil && opts.StateKey == "" {
return errors.New("no state key or prefs provided")
}
if b.c != nil {
// TODO(apenwarr): avoid the need to reinit controlclient.
// This will trigger a full relogin/reconfigure cycle every
// time a Handle reconnects to the backend. Ideally, we
// would send the new Prefs and everything would get back
// into sync with the minimal changes. But that's not how it
// is right now, which is a sign that the code is still too
// complicated.
b.c.Shutdown()
}
if opts.Prefs != nil {
b.logf("Start: %v\n", opts.Prefs.Pretty())
} else {
b.logf("Start\n")
}
hi := controlclient.NewHostinfo()
hi.BackendLogID = b.backendLogID
hi.FrontendLogID = opts.FrontendLogID
b.mu.Lock()
hi.Services = b.hiCache.Services // keep any previous session
b.hiCache = hi
b.state = NoState
if err := b.loadStateWithLock(opts.StateKey, opts.Prefs); err != nil {
b.mu.Unlock()
return fmt.Errorf("loading requested state: %v", err)
}
b.serverURL = b.prefs.ControlURL
hi.RoutableIPs = append(hi.RoutableIPs, b.prefs.AdvertiseRoutes...)
b.notify = opts.Notify
b.netMapCache = nil
b.mu.Unlock()
b.updateFilter()
var err error
persist := b.prefs.Persist
if persist == nil {
// let controlclient initialize it
persist = &controlclient.Persist{}
}
cli, err := controlclient.New(controlclient.Options{
Logf: func(fmt string, args ...interface{}) {
b.logf("control: "+fmt, args...)
},
Persist: *persist,
ServerURL: b.serverURL,
Hostinfo: &hi,
KeepAlive: true,
NewDecompressor: b.newDecompressor,
})
if err != nil {
return err
}
b.mu.Lock()
b.c = cli
b.mu.Unlock()
if b.endPoints != nil {
cli.UpdateEndpoints(0, b.endPoints)
}
cli.SetStatusFunc(func(new controlclient.Status) {
if new.LoginFinished != nil {
// Auth completed, unblock the engine
b.blockEngineUpdates(false)
b.authReconfig()
b.send(Notify{LoginFinished: &empty.Message{}})
}
if new.Persist != nil {
persist := *new.Persist // copy
b.prefs.Persist = &persist
if b.stateKey != "" {
if err := b.store.WriteState(b.stateKey, b.prefs.ToBytes()); err != nil {
b.logf("Failed to save new controlclient state: %v", err)
}
}
np := b.prefs
b.send(Notify{Prefs: &np})
}
if new.NetMap != nil {
if b.netMapCache != nil && b.cmpDiff != nil {
s1 := strings.Split(b.netMapCache.Concise(), "\n")
s2 := strings.Split(new.NetMap.Concise(), "\n")
b.logf("netmap diff:\n%v\n", b.cmpDiff(s1, s2))
}
b.netMapCache = new.NetMap
b.send(Notify{NetMap: new.NetMap})
b.updateFilter()
}
if new.URL != "" {
b.logf("Received auth URL: %.20v...\n", new.URL)
b.mu.Lock()
interact := b.interact
b.authURL = new.URL
b.mu.Unlock()
if interact > 0 {
b.popBrowserAuthNow()
}
}
if new.Err != "" {
// TODO(crawshaw): display in the UI.
log.Print(new.Err)
return
}
if new.NetMap != nil {
if b.prefs.WantRunning || b.State() == NeedsLogin {
b.prefs.WantRunning = true
}
b.SetPrefs(b.prefs)
}
b.stateMachine()
})
b.e.SetStatusCallback(func(s *wgengine.Status, err error) {
if err != nil {
b.logf("wgengine status error: %#v", err)
return
}
if s == nil {
log.Fatalf("weird: non-error wgengine update with status=nil\n")
}
b.mu.Lock()
es := b.parseWgStatus(s)
b.mu.Unlock()
b.engineStatus = es
if b.c != nil {
b.c.UpdateEndpoints(0, s.LocalAddrs)
}
b.endPoints = append([]string{}, s.LocalAddrs...)
b.stateMachine()
b.statusLock.Lock()
b.statusChanged.Broadcast()
b.statusLock.Unlock()
b.send(Notify{Engine: &es})
})
blid := b.backendLogID
b.logf("Backend: logs: be:%v fe:%v\n", blid, opts.FrontendLogID)
b.send(Notify{BackendLogID: &blid})
nprefs := b.prefs // make a copy
b.send(Notify{Prefs: &nprefs})
cli.Login(nil, controlclient.LoginDefault)
return nil
}
func (b *LocalBackend) updateFilter() {
if !b.Prefs().UsePacketFilter {
b.e.SetFilter(filter.NewAllowAll())
} else if b.netMapCache == nil {
// Not configured yet, block everything
b.e.SetFilter(filter.NewAllowNone())
} else {
b.logf("netmap packet filter: %v\n", b.netMapCache.PacketFilter)
b.e.SetFilter(filter.New(b.netMapCache.PacketFilter))
}
}
func (b *LocalBackend) runPoller() {
for {
ports := <-b.portpoll.C
if ports == nil {
break
}
sl := []tailcfg.Service{}
for _, p := range ports {
var proto tailcfg.ServiceProto
if p.Proto == "tcp" {
proto = tailcfg.TCP
} else if p.Proto == "udp" {
proto = tailcfg.UDP
}
if p.Port == 53 || p.Port == 68 ||
p.Port == 5353 || p.Port == 5355 {
// uninteresting system services
continue
}
s := tailcfg.Service{
Proto: proto,
Port: p.Port,
Description: p.Process,
}
sl = append(sl, s)
}
b.mu.Lock()
hi := b.hiCache
hi.Services = sl
b.hiCache = hi
cli := b.c
b.mu.Unlock()
// b.c might not be started yet
if cli != nil {
cli.SetHostinfo(hi)
}
}
}
func (b *LocalBackend) send(n Notify) {
if b.notify != nil {
n.Version = version.LONG
b.notify(n)
}
}
func (b *LocalBackend) popBrowserAuthNow() {
b.mu.Lock()
url := b.authURL
b.interact = 0
b.authURL = ""
b.mu.Unlock()
b.logf("popBrowserAuthNow: url=%v\n", url != "")
b.blockEngineUpdates(true)
b.stopEngineAndWait()
b.send(Notify{BrowseToURL: &url})
if b.State() == Running {
b.enterState(Starting)
}
}
func (b *LocalBackend) loadStateWithLock(key StateKey, prefs *Prefs) error {
if prefs == nil && key == "" {
panic("state key and prefs are both unset")
}
if key == "" {
// Frontend fully owns the state, we just need to obey it.
b.logf("Using frontend prefs")
b.prefs = *prefs
b.stateKey = ""
return nil
}
if prefs != nil {
// Backend owns the state, but frontend is trying to migrate
// state into the backend.
b.logf("Importing frontend prefs into backend store")
if err := b.store.WriteState(key, prefs.ToBytes()); err != nil {
return fmt.Errorf("store.WriteState: %v", err)
}
}
b.logf("Using backend prefs")
bs, err := b.store.ReadState(key)
if err != nil {
if err == ErrStateNotExist {
b.prefs = NewPrefs()
b.stateKey = key
b.logf("Created empty state for %q", key)
return nil
}
return fmt.Errorf("store.ReadState(%q): %v", key, err)
}
b.prefs, err = PrefsFromBytes(bs, false)
if err != nil {
return fmt.Errorf("PrefsFromBytes: %v", err)
}
b.stateKey = key
return nil
}
func (b *LocalBackend) State() State {
b.mu.Lock()
defer b.mu.Unlock()
return b.state
}
func (b *LocalBackend) EngineStatus() EngineStatus {
b.mu.Lock()
defer b.mu.Unlock()
return b.engineStatus
}
func (b *LocalBackend) StartLoginInteractive() {
b.assertClient()
b.mu.Lock()
b.interact++
url := b.authURL
b.mu.Unlock()
b.logf("StartLoginInteractive: url=%v\n", url != "")
if url != "" {
b.popBrowserAuthNow()
} else {
b.c.Login(nil, controlclient.LoginInteractive)
}
}
func (b *LocalBackend) FakeExpireAfter(x time.Duration) {
b.logf("FakeExpireAfter: %v\n", x)
if b.netMapCache != nil {
e := b.netMapCache.Expiry
if e.IsZero() || time.Until(e) > x {
b.netMapCache.Expiry = time.Now().Add(x)
}
b.send(Notify{NetMap: b.netMapCache})
}
}
func (b *LocalBackend) LocalAddrs() []wgcfg.CIDR {
if b.netMapCache != nil {
return b.netMapCache.Addresses
} else {
return nil
}
}
func (b *LocalBackend) Expiry() time.Time {
if b.netMapCache != nil {
return b.netMapCache.Expiry
} else {
return time.Time{}
}
}
func (b *LocalBackend) parseWgStatus(s *wgengine.Status) EngineStatus {
var ss []string
var rx, tx wgengine.ByteCount
peers := make(map[tailcfg.NodeKey]wgengine.PeerStatus)
live := 0
for _, p := range s.Peers {
if p.LastHandshake.IsZero() {
ss = append(ss, "x")
} else {
ss = append(ss, fmt.Sprintf("%d/%d", p.RxBytes, p.TxBytes))
live++
peers[p.NodeKey] = p
}
rx += p.RxBytes
tx += p.TxBytes
}
b.logf("v%v peers: %v\n", version.LONG, strings.Join(ss, " "))
return EngineStatus{
RBytes: rx,
WBytes: tx,
NumLive: live,
LivePeers: peers,
}
}
func (b *LocalBackend) AdminPageURL() string {
return b.serverURL + "/admin/machines"
}
func (b *LocalBackend) Prefs() Prefs {
b.mu.Lock()
defer b.mu.Unlock()
return b.prefs
}
func (b *LocalBackend) SetPrefs(new Prefs) {
b.mu.Lock()
old := b.prefs
new.Persist = old.Persist // caller isn't allowed to override this
b.prefs = new
if b.stateKey != "" {
if err := b.store.WriteState(b.stateKey, b.prefs.ToBytes()); err != nil {
b.logf("Failed to save new controlclient state: %v", err)
}
}
oldHi := b.hiCache
newHi := oldHi.Copy()
newHi.RoutableIPs = append([]wgcfg.CIDR(nil), b.prefs.AdvertiseRoutes...)
b.hiCache = *newHi
cli := b.c
b.mu.Unlock()
if cli != nil && !oldHi.Equal(newHi) {
cli.SetHostinfo(*newHi)
}
if old.WantRunning != new.WantRunning {
b.stateMachine()
} else {
b.authReconfig()
}
b.logf("SetPrefs: %v\n", new.Pretty())
b.send(Notify{Prefs: &new})
}
// Note: return value may be nil, if we haven't received a netmap yet.
func (b *LocalBackend) NetMap() *controlclient.NetworkMap {
return b.netMapCache
}
func (b *LocalBackend) blockEngineUpdates(block bool) {
// TODO(apenwarr): probably need mutex here (and several other places)
b.logf("blockEngineUpdates(%v)\n", block)
b.mu.Lock()
b.blocked = block
b.mu.Unlock()
}
func (b *LocalBackend) authReconfig() {
b.mu.Lock()
blocked := b.blocked
uc := b.prefs
nm := b.netMapCache
b.mu.Unlock()
if blocked {
b.logf("authReconfig: blocked, skipping.\n")
return
}
if nm == nil {
b.logf("authReconfig: netmap not yet valid. Skipping.\n")
return
}
if !uc.WantRunning {
b.logf("authReconfig: skipping because !WantRunning.\n")
return
}
b.logf("Configuring wireguard connection.\n")
uflags := controlclient.UDefault
if uc.RouteAll {
uflags |= controlclient.UAllowDefaultRoute
// TODO(apenwarr): Make subnet routes a different pref?
uflags |= controlclient.UAllowSubnetRoutes
// TODO(apenwarr): Remove this once we sort out subnet routes.
// Right now default routes are broken in Windows, but
// controlclient doesn't properly send subnet routes. So
// let's convert a default route into a subnet route in order
// to allow experimentation.
uflags |= controlclient.UHackDefaultRoute
}
if uc.AllowSingleHosts {
uflags |= controlclient.UAllowSingleHosts
}
b.logf("reconfig: ra=%v dns=%v 0x%02x\n", uc.RouteAll, uc.CorpDNS, uflags)
if nm != nil {
dns := nm.DNS
dom := nm.DNSDomains
if !uc.CorpDNS {
dns = []wgcfg.IP{}
dom = []string{}
}
cfg, err := nm.WGCfg(uflags, dns)
if err != nil {
log.Fatalf("WGCfg: %v\n", err)
}
err = b.e.Reconfig(cfg, dom)
if err != nil {
b.logf("reconfig: %v", err)
}
}
}
func (b *LocalBackend) enterState(newState State) {
b.mu.Lock()
state := b.state
prefs := b.prefs
b.mu.Unlock()
if state == newState {
return
}
b.logf("Switching ipn state %v -> %v (WantRunning=%v)\n",
state, newState, prefs.WantRunning)
if b.notify != nil {
b.send(Notify{State: &newState})
}
b.state = newState
switch newState {
case NeedsLogin:
b.blockEngineUpdates(true)
fallthrough
case Stopped:
err := b.e.Reconfig(&wgcfg.Config{}, nil)
if err != nil {
b.logf("Reconfig(down): %v\n", err)
}
case Starting, NeedsMachineAuth:
b.authReconfig()
// Needed so that UpdateEndpoints can run
b.e.RequestStatus()
case Running:
break
default:
b.logf("Weird: unknown newState %#v\n", newState)
}
}
func (b *LocalBackend) nextState() State {
b.assertClient()
state := b.State()
if b.netMapCache == nil {
if b.c.AuthCantContinue() {
// Auth was interrupted or waiting for URL visit,
// so it won't proceed without human help.
return NeedsLogin
} else {
// Auth or map request needs to finish
return state
}
} else if !b.prefs.WantRunning {
return Stopped
} else if e := b.netMapCache.Expiry; !e.IsZero() && time.Until(e) <= 0 {
return NeedsLogin
} else if b.netMapCache.MachineStatus != tailcfg.MachineAuthorized {
// TODO(crawshaw): handle tailcfg.MachineInvalid
return NeedsMachineAuth
} else if state == NeedsMachineAuth {
// (if we get here, we know MachineAuthorized == true)
return Starting
} else if state == Starting {
if b.EngineStatus().NumLive > 0 {
return Running
} else {
return state
}
} else if state == Running {
return Running
} else {
return Starting
}
}
func (b *LocalBackend) RequestEngineStatus() {
b.e.RequestStatus()
}
// TODO(apenwarr): use a channel or something to prevent re-entrancy?
// Or maybe just call the state machine from fewer places.
func (b *LocalBackend) stateMachine() {
b.enterState(b.nextState())
}
func (b *LocalBackend) stopEngineAndWait() {
b.logf("stopEngineAndWait...\n")
b.e.Reconfig(&wgcfg.Config{}, nil)
b.requestEngineStatusAndWait()
b.logf("stopEngineAndWait: done.\n")
}
// Requests the wgengine status, and does not return until the status
// was delivered (to the usual callback).
func (b *LocalBackend) requestEngineStatusAndWait() {
b.logf("requestEngineStatusAndWait\n")
b.statusLock.Lock()
go b.e.RequestStatus()
b.logf("requestEngineStatusAndWait: waiting...\n")
b.statusChanged.Wait() // temporarily releases lock while waiting
b.logf("requestEngineStatusAndWait: got status update.\n")
b.statusLock.Unlock()
}
// NOTE(apenwarr): No easy way to persist logged-out status.
// Maybe that's for the better; if someone logs out accidentally,
// rebooting will fix it.
func (b *LocalBackend) Logout() {
b.assertClient()
b.netMapCache = nil
b.c.Logout()
b.netMapCache = nil
b.stateMachine()
}
func (b *LocalBackend) assertClient() {
if b.c == nil {
panic("LocalBackend.assertClient: b.c == nil")
}
}