tailscale/portlist/portlist.go

110 lines
2.1 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.
package portlist
import (
"fmt"
"sort"
"strings"
)
// Port is a listening port on the machine.
type Port struct {
Proto string // "tcp" or "udp"
Port uint16 // port number
Process string // optional process name, if found
inode string // OS-specific; "socket:[165614651]" on Linux
}
// List is a list of Ports.
type List []Port
func (a *Port) lessThan(b *Port) bool {
if a.Port < b.Port {
return true
} else if a.Port > b.Port {
return false
}
if a.Proto < b.Proto {
return true
} else if a.Proto > b.Proto {
return false
}
if a.inode < b.inode {
return true
} else if a.inode > b.inode {
return false
}
if a.Process < b.Process {
return true
} else if a.Process > b.Process {
return false
}
return false
}
func (a List) sameInodes(b List) bool {
if a == nil || b == nil || len(a) != len(b) {
return false
}
for i := range a {
if a[i].Proto != b[i].Proto ||
a[i].Port != b[i].Port ||
a[i].inode != b[i].inode {
return false
}
}
return true
}
func (pl List) String() string {
var sb strings.Builder
for _, v := range pl {
fmt.Fprintf(&sb, "%-3s %5d %-17s %#v\n",
v.Proto, v.Port, v.inode, v.Process)
}
return strings.TrimRight(sb.String(), "\n")
}
func GetList(prev List) (List, error) {
pl, err := listPorts()
if err != nil {
return nil, fmt.Errorf("listPorts: %s", err)
}
pl = sortAndDedup(pl)
if pl.sameInodes(prev) {
// Nothing changed, skip inode lookup
return 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 {
sort.Slice(ps, func(i, j int) bool {
return (&ps[i]).lessThan(&ps[j])
})
out := ps[:0]
var last Port
for _, p := range ps {
protoPort := Port{Proto: p.Proto, Port: p.Port}
if last == protoPort {
continue
}
out = append(out, p)
last = protoPort
}
return out
}