tailscale/portlist/portlist.go

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// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
// 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"
)
// 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 (requires suitable permissions)
Pid int // process ID, if known (requires suitable permissions)
}
// List is a list of Ports.
type List []Port
func (a *Port) lessThan(b *Port) bool {
if a.Port != b.Port {
return a.Port < b.Port
}
if a.Proto != b.Proto {
return a.Proto < b.Proto
}
return a.Process < b.Process
}
func (a *Port) equal(b *Port) bool {
return a.Port == b.Port &&
a.Proto == b.Proto &&
a.Process == b.Process
}
func (a List) equal(b List) bool {
if len(a) != len(b) {
return false
}
for i := range a {
if !a[i].equal(&b[i]) {
return false
}
}
return true
}
func (pl List) String() string {
var sb strings.Builder
for _, v := range pl {
fmt.Fprintf(&sb, "%-3s %5d %#v\n",
v.Proto, v.Port, v.Process)
}
return strings.TrimRight(sb.String(), "\n")
}
// 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 {
if last.Proto == p.Proto && last.Port == p.Port {
continue
}
out = append(out, p)
last = p
}
return out
}