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https://github.com/tailscale/tailscale.git
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131 lines
3.5 KiB
Go
131 lines
3.5 KiB
Go
// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package monitor
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import (
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"context"
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"errors"
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"time"
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"golang.zx2c4.com/wireguard/windows/tunnel/winipcfg"
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"tailscale.com/types/logger"
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)
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var (
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errClosed = errors.New("closed")
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)
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type eventMessage struct {
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eventType string
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}
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func (eventMessage) ignore() bool { return false }
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type winMon struct {
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logf logger.Logf
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ctx context.Context
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cancel context.CancelFunc
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messagec chan eventMessage
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addressChangeCallback *winipcfg.UnicastAddressChangeCallback
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routeChangeCallback *winipcfg.RouteChangeCallback
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// noDeadlockTicker exists just to have something scheduled as
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// far as the Go runtime is concerned. Otherwise "tailscaled
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// debug --monitor" thinks it's deadlocked with nothing to do,
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// as Go's runtime doesn't know about callbacks registered with
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// Windows.
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noDeadlockTicker *time.Ticker
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}
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func newOSMon(logf logger.Logf, _ *Mon) (osMon, error) {
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m := &winMon{
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logf: logf,
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messagec: make(chan eventMessage, 1),
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noDeadlockTicker: time.NewTicker(5000 * time.Hour), // arbitrary
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}
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var err error
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m.addressChangeCallback, err = winipcfg.RegisterUnicastAddressChangeCallback(m.unicastAddressChanged)
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if err != nil {
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m.logf("winipcfg.RegisterUnicastAddressChangeCallback error: %v", err)
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return nil, err
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}
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m.routeChangeCallback, err = winipcfg.RegisterRouteChangeCallback(m.routeChanged)
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if err != nil {
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m.addressChangeCallback.Unregister()
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m.logf("winipcfg.RegisterRouteChangeCallback error: %v", err)
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return nil, err
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}
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m.ctx, m.cancel = context.WithCancel(context.Background())
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return m, nil
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}
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func (m *winMon) Close() (ret error) {
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m.cancel()
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m.noDeadlockTicker.Stop()
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if m.addressChangeCallback != nil {
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if err := m.addressChangeCallback.Unregister(); err != nil {
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m.logf("addressChangeCallback.Unregister error: %v", err)
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ret = err
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} else {
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m.addressChangeCallback = nil
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}
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}
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if m.routeChangeCallback != nil {
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if err := m.routeChangeCallback.Unregister(); err != nil {
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m.logf("routeChangeCallback.Unregister error: %v", err)
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ret = err
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} else {
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m.routeChangeCallback = nil
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}
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}
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return
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}
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func (m *winMon) Receive() (message, error) {
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if m.ctx.Err() != nil {
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m.logf("Receive call on closed monitor")
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return nil, errClosed
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}
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t0 := time.Now()
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select {
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case msg := <-m.messagec:
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m.logf("got windows change event after %v: evt=%s", time.Since(t0).Round(time.Millisecond), msg.eventType)
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return msg, nil
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case <-m.ctx.Done():
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return nil, errClosed
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}
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}
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// unicastAddressChanged is the callback we register with Windows to call when unicast address changes.
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func (m *winMon) unicastAddressChanged(_ winipcfg.MibNotificationType, _ *winipcfg.MibUnicastIPAddressRow) {
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// start a goroutine to finish our work, to return to Windows out of this callback
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go m.somethingChanged("addr")
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}
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// routeChanged is the callback we register with Windows to call when route changes.
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func (m *winMon) routeChanged(_ winipcfg.MibNotificationType, _ *winipcfg.MibIPforwardRow2) {
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// start a goroutine to finish our work, to return to Windows out of this callback
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go m.somethingChanged("route")
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}
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// somethingChanged gets called from OS callbacks whenever address or route changes.
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func (m *winMon) somethingChanged(evt string) {
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select {
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case <-m.ctx.Done():
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return
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case m.messagec <- eventMessage{eventType: evt}:
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return
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}
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}
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