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portlist: collect IPv6 listening sockets on linux.
This is important because some of those v6 sockets are actually dual-stacked sockets, so this is our only chance of discovering some services. Fixes #1443. Signed-off-by: David Anderson <danderson@tailscale.com>
This commit is contained in:
David Anderson
Dave Anderson
parent
82edf94df7
commit
63a9adeb6c
@ -10,6 +10,7 @@
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"io"
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"io/ioutil"
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"os"
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"path/filepath"
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"runtime"
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"sort"
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"strconv"
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@ -26,19 +27,25 @@
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// TODO(apenwarr): Include IPv6 ports eventually.
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// Right now we don't route IPv6 anyway so it's better to exclude them.
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var sockfiles = []string{"/proc/net/tcp", "/proc/net/udp"}
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var protos = []string{"tcp", "udp"}
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var sockfiles = []string{"/proc/net/tcp", "/proc/net/tcp6", "/proc/net/udp", "/proc/net/udp6"}
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var sawProcNetPermissionErr syncs.AtomicBool
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const (
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v6Localhost = "00000000000000000000000001000000:"
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v6Any = "00000000000000000000000000000000:0000"
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v4Localhost = "0100007F:"
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v4Any = "00000000:0000"
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)
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func listPorts() (List, error) {
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if sawProcNetPermissionErr.Get() {
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return nil, nil
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}
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l := []Port{}
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for pi, fname := range sockfiles {
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proto := protos[pi]
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for _, fname := range sockfiles {
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proto := strings.TrimSuffix(filepath.Base(fname), "6")
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// Android 10+ doesn't allow access to this anymore.
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// https://developer.android.com/about/versions/10/privacy/changes#proc-net-filesystem
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@ -59,47 +66,12 @@ func listPorts() (List, error) {
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defer f.Close()
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r := bufio.NewReader(f)
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// skip header row
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_, err = r.ReadString('\n')
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ports, err := parsePorts(r, proto)
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if err != nil {
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return nil, err
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return nil, fmt.Errorf("parsing %q: %w", fname, err)
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}
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for err == nil {
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line, err := r.ReadString('\n')
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if err == io.EOF {
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break
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}
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if err != nil {
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return nil, err
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}
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// sl local rem ... inode
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words := strings.Fields(line)
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local := words[1]
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rem := words[2]
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inode := words[9]
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// If a port is bound to 127.0.0.1, ignore it.
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if strings.HasPrefix(local, "0100007F:") {
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continue
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}
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if rem != "00000000:0000" {
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// not a "listener" port
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continue
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}
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portv, err := strconv.ParseUint(local[9:], 16, 16)
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if err != nil {
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return nil, fmt.Errorf("%#v: %s", local[9:], err)
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}
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inodev := fmt.Sprintf("socket:[%s]", inode)
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l = append(l, Port{
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Proto: proto,
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Port: uint16(portv),
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inode: inodev,
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})
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}
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l = append(l, ports...)
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}
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sort.Slice(l, func(i, j int) bool {
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@ -109,6 +81,62 @@ func listPorts() (List, error) {
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return l, nil
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}
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func parsePorts(r *bufio.Reader, proto string) ([]Port, error) {
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var ret []Port
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// skip header row
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_, err := r.ReadString('\n')
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if err != nil {
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return nil, err
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}
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for err == nil {
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line, err := r.ReadString('\n')
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if err == io.EOF {
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break
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}
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if err != nil {
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return nil, err
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}
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// sl local rem ... inode
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words := strings.Fields(line)
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local := words[1]
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rem := words[2]
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inode := words[9]
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// If a port is bound to localhost, ignore it.
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// TODO: localhost is bigger than 1 IP, we need to ignore
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// more things.
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if strings.HasPrefix(local, v4Localhost) || strings.HasPrefix(local, v6Localhost) {
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continue
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}
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if rem != v4Any && rem != v6Any {
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// not a "listener" port
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continue
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}
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// Don't use strings.Split here, because it causes
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// allocations significant enough to show up in profiles.
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i := strings.IndexByte(local, ':')
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if i == -1 {
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return nil, fmt.Errorf("%q unexpectedly didn't have a colon", local)
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}
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portv, err := strconv.ParseUint(local[i+1:], 16, 16)
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if err != nil {
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return nil, fmt.Errorf("%#v: %s", local[9:], err)
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}
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inodev := fmt.Sprintf("socket:[%s]", inode)
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ret = append(ret, Port{
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Proto: proto,
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Port: uint16(portv),
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inode: inodev,
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})
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}
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return ret, nil
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}
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func addProcesses(pl []Port) ([]Port, error) {
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pm := map[string]*Port{} // by Port.inode
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for i := range pl {
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67
portlist/portlist_linux_test.go
Normal file
67
portlist/portlist_linux_test.go
Normal file
@ -0,0 +1,67 @@
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// 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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package portlist
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import (
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"bufio"
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"bytes"
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"testing"
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"github.com/google/go-cmp/cmp"
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)
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func TestParsePorts(t *testing.T) {
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tests := []struct {
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name string
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in string
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want []Port
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}{
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{
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name: "empty",
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in: "header line (ignored)\n",
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want: nil,
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},
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{
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name: "ipv4",
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in: `header line
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0: 0100007F:0277 00000000:0000 0A 00000000:00000000 00:00000000 00000000 0 0 22303 1 0000000000000000 100 0 0 10 0
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1: 00000000:0016 00000000:0000 0A 00000000:00000000 00:00000000 00000000 0 0 34062 1 0000000000000000 100 0 0 10 0
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2: 5501A8C0:ADD4 B25E9536:01BB 01 00000000:00000000 02:00000B2B 00000000 1000 0 155276677 2 0000000000000000 22 4 30 10 -1
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`,
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want: []Port{
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{Proto: "tcp", Port: 22, inode: "socket:[34062]"},
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},
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},
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{
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name: "ipv6",
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in: ` sl local_address remote_address st tx_queue rx_queue tr tm->when retrnsmt uid timeout inode
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0: 00000000000000000000000001000000:0277 00000000000000000000000000000000:0000 0A 00000000:00000000 00:00000000 00000000 0 0 35720 1 0000000000000000 100 0 0 10 0
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1: 00000000000000000000000000000000:1F91 00000000000000000000000000000000:0000 0A 00000000:00000000 00:00000000 00000000 1000 0 142240557 1 0000000000000000 100 0 0 10 0
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2: 00000000000000000000000000000000:0016 00000000000000000000000000000000:0000 0A 00000000:00000000 00:00000000 00000000 0 0 34064 1 0000000000000000 100 0 0 10 0
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3: 69050120005716BC64906EBE009ECD4D:D506 0047062600000000000000006E171268:01BB 01 00000000:00000000 02:0000009E 00000000 1000 0 151042856 2 0000000000000000 21 4 28 10 -1
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`,
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want: []Port{
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{Proto: "tcp", Port: 8081, inode: "socket:[142240557]"},
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{Proto: "tcp", Port: 22, inode: "socket:[34064]"},
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},
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},
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}
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for _, test := range tests {
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t.Run(test.name, func(t *testing.T) {
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buf := bytes.NewBufferString(test.in)
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r := bufio.NewReader(buf)
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got, err := parsePorts(r, "tcp")
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if err != nil {
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t.Fatal(err)
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}
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if diff := cmp.Diff(got, test.want, cmp.AllowUnexported(Port{})); diff != "" {
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t.Errorf("unexpected parsed ports (-got+want):\n%s", diff)
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}
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})
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}
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}
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