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portlist: add package doc, file comments, move a method to the right file

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And respect envknob earlier. NewPoller has one caller and ignores
errors; they just signal ipnlocal to log a warning and not use the
portlist poller.

Change-Id: I4a33af936fe780cca8c7197d4d74ac31a1dc01e3
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
This commit is contained in:
Brad Fitzpatrick 2022-10-22 21:10:13 -07:00 committed by Brad Fitzpatrick
parent 774fa72d32
commit 70dde89c34
2 changed files with 35 additions and 25 deletions
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31
portlist/poller.go
View File

@ -2,16 +2,23 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// 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 (
"context"
"errors"
"fmt"
"time"
"tailscale.com/envknob"
"tailscale.com/version"
)
var debugDisablePortlist = envknob.RegisterBool("TS_DEBUG_DISABLE_PORTLIST")
// Poller scans the systems for listening ports periodically and sends
// the results to C.
type Poller struct {
@ -35,6 +42,9 @@ func NewPoller() (*Poller, error) {
if version.OS() == "iOS" {
return nil, errors.New("not available on iOS")
}
if debugDisablePortlist() {
return nil, errors.New("portlist disabled by envknob")
}
p := &Poller{
c: make(chan List),
runDone: make(chan struct{}),
@ -113,3 +123,24 @@ func (p *Poller) Run(ctx context.Context) error {
}
}
}
func (p *Poller) getList() (List, error) {
if debugDisablePortlist() {
return nil, nil
}
var err error
p.scratch, err = appendListeningPorts(p.scratch[:0])
if err != nil {
return nil, fmt.Errorf("listPorts: %s", err)
}
pl := sortAndDedup(p.scratch)
if pl.sameInodes(p.prev) {
// Nothing changed, skip inode lookup
return p.prev, nil
}
pl, err = addProcesses(pl)
if err != nil {
return nil, fmt.Errorf("addProcesses: %s", err)
}
return pl, nil
}

29
portlist/portlist.go
View File

@ -2,14 +2,16 @@
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// This file is just the types. The bulk of the code is in poller.go.
// The portlist package contains code that checks what ports are open and
// listening on the current machine.
package portlist
import (
"fmt"
"sort"
"strings"
"tailscale.com/envknob"
)
// Port is a listening port on the machine.
@ -74,29 +76,6 @@ func (pl List) String() string {
return strings.TrimRight(sb.String(), "\n")
}
var debugDisablePortlist = envknob.RegisterBool("TS_DEBUG_DISABLE_PORTLIST")
func (p *Poller) getList() (List, error) {
if debugDisablePortlist() {
return nil, nil
}
var err error
p.scratch, err = appendListeningPorts(p.scratch[:0])
if err != nil {
return nil, fmt.Errorf("listPorts: %s", err)
}
pl := sortAndDedup(p.scratch)
if pl.sameInodes(p.prev) {
// Nothing changed, skip inode lookup
return p.prev, nil
}
pl, err = addProcesses(pl)
if err != nil {
return nil, fmt.Errorf("addProcesses: %s", err)
}
return pl, nil
}
// sortAndDedup sorts ps in place (by Port.lessThan) and then returns
// a subset of it with duplicate (Proto, Port) removed.
func sortAndDedup(ps List) List {