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a5da4ed981
This adds "//go:build" lines and tidies up existing "// +build" lines. Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
90 lines
2.3 KiB
Go
90 lines
2.3 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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//go:build !freebsd && !windows && !darwin
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// +build !freebsd,!windows,!darwin
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package monitor
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import (
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"bytes"
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"errors"
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"os"
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"runtime"
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"sync"
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"time"
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"tailscale.com/net/interfaces"
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"tailscale.com/types/logger"
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)
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func newPollingMon(logf logger.Logf, m *Mon) (osMon, error) {
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return &pollingMon{
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logf: logf,
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m: m,
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stop: make(chan struct{}),
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}, nil
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}
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// pollingMon is a bad but portable implementation of the link monitor
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// that works by polling the interface state every 10 seconds, in lieu
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// of anything to subscribe to.
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type pollingMon struct {
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logf logger.Logf
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m *Mon
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closeOnce sync.Once
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stop chan struct{}
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}
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func (pm *pollingMon) Close() error {
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pm.closeOnce.Do(func() {
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close(pm.stop)
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})
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return nil
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}
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func (pm *pollingMon) isCloudRun() bool {
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// https: //cloud.google.com/run/docs/reference/container-contract#env-vars
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if os.Getenv("K_REVISION") == "" || os.Getenv("K_CONFIGURATION") == "" ||
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os.Getenv("K_SERVICE") == "" || os.Getenv("PORT") == "" {
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return false
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}
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vers, err := os.ReadFile("/proc/version")
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if err != nil {
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pm.logf("Failed to read /proc/version: %v", err)
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return false
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}
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return string(bytes.TrimSpace(vers)) == "Linux version 4.4.0 #1 SMP Sun Jan 10 15:06:54 PST 2016"
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}
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func (pm *pollingMon) Receive() (message, error) {
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d := 10 * time.Second
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if runtime.GOOS == "android" {
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// We'll have Android notify the link monitor to wake up earlier,
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// so this can go very slowly there, to save battery.
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// https://github.com/tailscale/tailscale/issues/1427
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d = 10 * time.Minute
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}
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if pm.isCloudRun() {
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// Cloud Run routes never change at runtime. the containers are killed within
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// 15 minutes by default, set the interval long enough to be effectively infinite.
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pm.logf("monitor polling: Cloud Run detected, reduce polling interval to 24h")
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d = 24 * time.Hour
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}
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ticker := time.NewTicker(d)
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defer ticker.Stop()
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base := pm.m.InterfaceState()
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for {
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if cur, err := pm.m.interfaceStateUncached(); err == nil && !cur.EqualFiltered(base, interfaces.FilterInteresting) {
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return unspecifiedMessage{}, nil
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}
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select {
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case <-ticker.C:
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case <-pm.stop:
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return nil, errors.New("stopped")
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}
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}
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}
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