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tailscale/portlist/portlist_macos.go

111 lines
2.6 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.
// +build darwin,amd64 go1.16,darwin,arm64
package portlist
import (
"bufio"
"bytes"
"fmt"
"log"
"os"
"os/exec"
"strings"
"sync/atomic"
"time"
)
// We have to run netstat, which is a bit expensive, so don't do it too often.
const pollInterval = 5 * time.Second
func listPorts() (List, error) {
return listPortsNetstat("-na")
}
var lsofFailed int64 // atomic bool
// In theory, lsof could replace the function of both listPorts() and
// addProcesses(), since it provides a superset of the netstat output.
// However, "netstat -na" runs ~100x faster than lsof on my machine, so
// we should do it only if the list of open ports has actually changed.
//
// TODO(apenwarr): this fails in a macOS sandbox (ie. our usual case).
// We might as well just delete this code if we can't find a solution.
func addProcesses(pl []Port) ([]Port, error) {
if atomic.LoadInt64(&lsofFailed) != 0 {
// This previously failed in the macOS sandbox, so don't try again.
return pl, nil
}
exe, err := exec.LookPath("lsof")
if err != nil {
return nil, fmt.Errorf("lsof: lookup: %v", err)
}
output, err := exec.Command(exe, "-F", "-n", "-P", "-O", "-S2", "-T", "-i4", "-i6").Output()
if err != nil {
var stderr []byte
if xe, ok := err.(*exec.ExitError); ok {
stderr = xe.Stderr
}
// fails when run in a macOS sandbox, so make this non-fatal.
if atomic.CompareAndSwapInt64(&lsofFailed, 0, 1) {
log.Printf("portlist: can't run lsof in Mac sandbox; omitting process names from service list. Error details: %v, %s", err, bytes.TrimSpace(stderr))
}
return pl, nil
}
type ProtoPort struct {
proto string
port uint16
}
m := map[ProtoPort]*Port{}
for i := range pl {
pp := ProtoPort{pl[i].Proto, pl[i].Port}
m[pp] = &pl[i]
}
r := bytes.NewReader(output)
scanner := bufio.NewScanner(r)
var cmd, proto string
for scanner.Scan() {
line := scanner.Text()
if line == "" {
continue
}
field, val := line[0], line[1:]
switch field {
case 'p':
// starting a new process
cmd = ""
proto = ""
case 'c':
cmd = val
case 'P':
proto = strings.ToLower(val)
case 'n':
if strings.Contains(val, "->") {
continue
}
// a listening port
port := parsePort(val)
if port > 0 {
pp := ProtoPort{proto, uint16(port)}
p := m[pp]
switch {
case p != nil:
p.Process = cmd
case isLoopbackAddr(val):
// ignore
default:
fmt.Fprintf(os.Stderr, "weird: missing %v\n", pp)
}
}
}
}
return pl, nil
}