tailscale/ipn/backend.go
David Anderson 5bc632271b Introduce a state store to LocalBackend.
The store is passed-in by callers of NewLocalBackend and
ipnserver.Run, but currently all callers are hardcoded to
an in-memory store. The store is unused.

Signed-Off-By: David Anderson <dave@natulte.net>
2020-02-13 19:26:53 -08:00

113 lines
3.9 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 (
"time"
"tailscale.com/control/controlclient"
"tailscale.com/tailcfg"
"tailscale.com/wgengine"
)
type State int
const (
NoState = State(iota)
NeedsLogin
NeedsMachineAuth
Stopped
Starting
Running
)
func (s State) String() string {
return [...]string{"NoState", "NeedsLogin", "NeedsMachineAuth",
"Stopped", "Starting", "Running"}[s]
}
type EngineStatus struct {
RBytes, WBytes wgengine.ByteCount
NumLive int
LivePeers map[tailcfg.NodeKey]wgengine.PeerStatus
}
type NetworkMap = controlclient.NetworkMap
// In any given notification, any or all of these may be nil, meaning
// that they have not changed.
type Notify struct {
Version string // version number of IPN backend
ErrMessage *string // critical error message, if any
LoginFinished *struct{} // event: login process succeeded
State *State // current IPN state has changed
Prefs *Prefs // preferences were changed
NetMap *NetworkMap // new netmap received
Engine *EngineStatus // wireguard engine stats
BrowseToURL *string // UI should open a browser right now
BackendLogID *string // public logtail id used by backend
}
// StateKey is an opaque identifier for a set of LocalBackend state
// (preferences, private keys, etc.).
//
// The reason we need this is that the Tailscale agent may be running
// on a multi-user machine, in a context where a single daemon is
// shared by several consecutive users. Ideally we would just use the
// username of the connected frontend as the StateKey.
//
// However, on Windows, there seems to be no safe way to figure out
// the owning user of a process connected over IPC mechanisms
// (sockets, named pipes). So instead, on Windows, we use a
// capability-oriented system where the frontend generates a random
// identifier for itself, and uses that as the StateKey when talking
// to the backend. That way, while we can't identify an OS user by
// name, we can tell two different users apart, because they'll have
// different opaque state keys (and no access to each others's keys).
//
// It would be much nicer if we could just figure out the OS user that
// owns the connected frontend, but here we are.
type StateKey string
type Options struct {
// Public logtail id used by frontend.
FrontendLogID string
// Base URL for the tailcontrol server to talk to.
ServerURL string
// StateKey and Prefs together define the state the backend should
// use:
// - StateKey=="" && Prefs!=nil: use Prefs for internal state,
// don't persist changes in the backend.
// - StateKey!="" && Prefs==nil: load the given backend-side
// state and use/update that.
// - StateKey!="" && Prefs!=nil: like the previous case, but do
// an initial overwrite of backend state with Prefs.
StateKey StateKey
Prefs *Prefs
// Callback for backend events.
Notify func(Notify) `json:"-"`
}
type Backend interface {
// Start or restart the backend, because a new Handle has connected.
Start(opts Options) error
// Start a new interactive login. This should trigger a new
// BrowseToURL notification eventually.
StartLoginInteractive()
// Terminate the current login session and stop the wireguard engine.
Logout()
// Install a new set of user preferences, including WantRunning.
// This may cause the wireguard engine to reconfigure or stop.
SetPrefs(new Prefs)
// Poll for an update from the wireguard engine. Only needed if
// you want to display byte counts. Connection events are emitted
// automatically without polling.
RequestEngineStatus()
// Pretend the current key is going to expire after duration x.
// This is useful for testing GUIs to make sure they react properly
// with keys that are going to expire.
FakeExpireAfter(x time.Duration)
}