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120273d7f6
I noticed portlist when looking at some profiles and hadn't looked at the code much before. This is a first pass over it. It allocates a fair bit. More love remains, but this does a bit: name old time/op new time/op delta GetList-8 9.92ms ± 8% 9.64ms ±12% ~ (p=0.247 n=10+10) name old alloc/op new alloc/op delta GetList-8 931kB ± 0% 869kB ± 0% -6.70% (p=0.000 n=10+10) name old allocs/op new allocs/op delta GetList-8 4.59k ± 0% 3.69k ± 1% -19.71% (p=0.000 n=10+10) Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
101 lines
2.3 KiB
Go
101 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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// +build !linux,!windows
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package portlist
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import (
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"bufio"
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"bytes"
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"fmt"
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"log"
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"os"
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"strings"
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"time"
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exec "tailscale.com/tempfork/osexec"
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)
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// We have to run netstat, which is a bit expensive, so don't do it too often.
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const pollInterval = 5 * time.Second
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func listPorts() (List, error) {
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return listPortsNetstat("-na")
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}
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// In theory, lsof could replace the function of both listPorts() and
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// addProcesses(), since it provides a superset of the netstat output.
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// However, "netstat -na" runs ~100x faster than lsof on my machine, so
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// we should do it only if the list of open ports has actually changed.
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//
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// TODO(apenwarr): this fails in a macOS sandbox (ie. our usual case).
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// We might as well just delete this code if we can't find a solution.
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func addProcesses(pl []Port) ([]Port, error) {
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exe, err := exec.LookPath("lsof")
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if err != nil {
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return nil, fmt.Errorf("lsof: lookup: %v", err)
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}
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c := exec.Cmd{
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Path: exe,
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Args: []string{exe, "-F", "-n", "-P", "-O", "-S2", "-T", "-i4", "-i6"},
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}
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output, err := c.Output()
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if err != nil {
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xe, ok := err.(*exec.ExitError)
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stderr := ""
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if ok {
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stderr = strings.TrimSpace(string(xe.Stderr))
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}
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// fails when run in a macOS sandbox, so make this non-fatal.
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log.Printf("portlist: lsof: %v (%q)\n", err, stderr)
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return pl, nil
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}
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type ProtoPort struct {
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proto string
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port uint16
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}
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m := map[ProtoPort]*Port{}
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for i := range pl {
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pp := ProtoPort{pl[i].Proto, pl[i].Port}
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m[pp] = &pl[i]
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}
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r := bytes.NewReader(output)
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scanner := bufio.NewScanner(r)
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var cmd, proto string
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for scanner.Scan() {
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line := scanner.Text()
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if line[0] == 'p' {
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// starting a new process
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cmd = ""
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proto = ""
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} else if line[0] == 'c' {
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cmd = line[1:len(line)]
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} else if line[0] == 'P' {
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proto = strings.ToLower(line[1:len(line)])
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} else if line[0] == 'n' {
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rest := line[1:len(line)]
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i := strings.Index(rest, "->")
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if i < 0 {
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// a listening port
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port := parsePort(rest)
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if port > 0 {
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pp := ProtoPort{proto, uint16(port)}
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p := m[pp]
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if p != nil {
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p.Process = cmd
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} else {
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fmt.Fprintf(os.Stderr, "weird: missing %v\n", pp)
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}
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}
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}
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}
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}
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return pl, nil
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}
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