mirror of
https://github.com/tailscale/tailscale.git
synced 2024-11-30 05:25:35 +00:00
123 lines
3.4 KiB
Go
123 lines
3.4 KiB
Go
// Copyright (c) Tailscale Inc & AUTHORS
|
|
// SPDX-License-Identifier: BSD-3-Clause
|
|
|
|
// This file contains the code related to the Poller type and its methods.
|
|
// The hot loop to keep efficient is Poller.Run.
|
|
|
|
package portlist
|
|
|
|
import (
|
|
"errors"
|
|
"fmt"
|
|
"runtime"
|
|
"slices"
|
|
"sync"
|
|
"time"
|
|
|
|
"tailscale.com/envknob"
|
|
)
|
|
|
|
var (
|
|
newOSImpl func(includeLocalhost bool) osImpl // if non-nil, constructs a new osImpl.
|
|
pollInterval = 5 * time.Second // default; changed by some OS-specific init funcs
|
|
debugDisablePortlist = envknob.RegisterBool("TS_DEBUG_DISABLE_PORTLIST")
|
|
)
|
|
|
|
// PollInterval is the recommended OS-specific interval
|
|
// to wait between *Poller.Poll method calls.
|
|
func PollInterval() time.Duration {
|
|
return pollInterval
|
|
}
|
|
|
|
// Poller scans the systems for listening ports periodically and sends
|
|
// the results to C.
|
|
type Poller struct {
|
|
// IncludeLocalhost controls whether services bound to localhost are included.
|
|
//
|
|
// This field should only be changed before calling Run.
|
|
IncludeLocalhost bool
|
|
|
|
// os, if non-nil, is an OS-specific implementation of the portlist getting
|
|
// code. When non-nil, it's responsible for getting the complete list of
|
|
// cached ports complete with the process name. That is, when set,
|
|
// addProcesses is not used.
|
|
// A nil values means we don't have code for getting the list on the current
|
|
// operating system.
|
|
os osImpl
|
|
initOnce sync.Once // guards init of os
|
|
initErr error
|
|
|
|
// scatch is memory for Poller.getList to reuse between calls.
|
|
scratch []Port
|
|
|
|
prev List // most recent data, not aliasing scratch
|
|
}
|
|
|
|
// osImpl is the OS-specific implementation of getting the open listening ports.
|
|
type osImpl interface {
|
|
Close() error
|
|
|
|
// AppendListeningPorts appends to base (which must have length 0 but
|
|
// optional capacity) the list of listening ports. The Port struct should be
|
|
// populated as completely as possible. Another pass will not add anything
|
|
// to it.
|
|
//
|
|
// The appended ports should be in a sorted (or at least stable) order so
|
|
// the caller can cheaply detect when there are no changes.
|
|
AppendListeningPorts(base []Port) ([]Port, error)
|
|
}
|
|
|
|
func (p *Poller) setPrev(pl List) {
|
|
// Make a copy, as the pass in pl slice aliases pl.scratch and we don't want
|
|
// that to except to the caller.
|
|
p.prev = slices.Clone(pl)
|
|
}
|
|
|
|
// init initializes the Poller by ensuring it has an underlying
|
|
// OS implementation and is not turned off by envknob.
|
|
func (p *Poller) init() {
|
|
switch {
|
|
case debugDisablePortlist():
|
|
p.initErr = errors.New("portlist disabled by envknob")
|
|
case newOSImpl == nil:
|
|
p.initErr = errors.New("portlist poller not implemented on " + runtime.GOOS)
|
|
default:
|
|
p.os = newOSImpl(p.IncludeLocalhost)
|
|
}
|
|
}
|
|
|
|
// Close closes the Poller.
|
|
func (p *Poller) Close() error {
|
|
if p.initErr != nil {
|
|
return p.initErr
|
|
}
|
|
if p.os == nil {
|
|
return nil
|
|
}
|
|
return p.os.Close()
|
|
}
|
|
|
|
// Poll returns the list of listening ports, if changed from
|
|
// a previous call as indicated by the changed result.
|
|
func (p *Poller) Poll() (ports []Port, changed bool, err error) {
|
|
p.initOnce.Do(p.init)
|
|
if p.initErr != nil {
|
|
return nil, false, fmt.Errorf("error initializing poller: %w", p.initErr)
|
|
}
|
|
pl, err := p.getList()
|
|
if err != nil {
|
|
return nil, false, err
|
|
}
|
|
if pl.equal(p.prev) {
|
|
return nil, false, nil
|
|
}
|
|
p.setPrev(pl)
|
|
return p.prev, true, nil
|
|
}
|
|
|
|
func (p *Poller) getList() (List, error) {
|
|
var err error
|
|
p.scratch, err = p.os.AppendListeningPorts(p.scratch[:0])
|
|
return p.scratch, err
|
|
}
|