chirp: handle multiline responses from BIRD
Also add tests to verify the parsing logic. Signed-off-by: Maisem Ali <maisem@tailscale.com>pull/3868/head
Maisem Ali
Maisem Ali
parent
fa612c28cf
commit
e3dccfd7ff
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@ -10,6 +10,7 @@ import (
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"bufio"
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"fmt"
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"net"
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"regexp"
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"strings"
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)
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@ -19,9 +20,9 @@ func New(socket string) (*BIRDClient, error) {
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if err != nil {
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return nil, fmt.Errorf("failed to connect to BIRD: %w", err)
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}
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b := &BIRDClient{socket: socket, conn: conn, bs: bufio.NewScanner(conn)}
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b := &BIRDClient{socket: socket, conn: conn, scanner: bufio.NewScanner(conn)}
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// Read and discard the first line as that is the welcome message.
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if _, err := b.readLine(); err != nil {
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if _, err := b.readResponse(); err != nil {
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return nil, err
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}
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return b, nil
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@ -29,9 +30,9 @@ func New(socket string) (*BIRDClient, error) {
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// BIRDClient handles communication with the BIRD Internet Routing Daemon.
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type BIRDClient struct {
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socket string
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conn net.Conn
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bs *bufio.Scanner
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socket string
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conn net.Conn
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scanner *bufio.Scanner
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}
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// Close closes the underlying connection to BIRD.
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@ -39,7 +40,7 @@ func (b *BIRDClient) Close() error { return b.conn.Close() }
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// DisableProtocol disables the provided protocol.
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func (b *BIRDClient) DisableProtocol(protocol string) error {
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out, err := b.exec("disable %s\n", protocol)
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out, err := b.exec("disable %s", protocol)
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if err != nil {
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return err
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}
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@ -53,7 +54,7 @@ func (b *BIRDClient) DisableProtocol(protocol string) error {
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// EnableProtocol enables the provided protocol.
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func (b *BIRDClient) EnableProtocol(protocol string) error {
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out, err := b.exec("enable %s\n", protocol)
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out, err := b.exec("enable %s", protocol)
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if err != nil {
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return err
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}
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@ -65,19 +66,51 @@ func (b *BIRDClient) EnableProtocol(protocol string) error {
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return fmt.Errorf("failed to enable %s: %v", protocol, out)
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}
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// BIRD CLI docs from https://bird.network.cz/?get_doc&v=20&f=prog-2.html#ss2.9
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// Each session of the CLI consists of a sequence of request and replies,
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// slightly resembling the FTP and SMTP protocols.
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// Requests are commands encoded as a single line of text,
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// replies are sequences of lines starting with a four-digit code
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// followed by either a space (if it's the last line of the reply) or
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// a minus sign (when the reply is going to continue with the next line),
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// the rest of the line contains a textual message semantics of which depends on the numeric code.
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// If a reply line has the same code as the previous one and it's a continuation line,
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// the whole prefix can be replaced by a single white space character.
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//
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// Reply codes starting with 0 stand for ‘action successfully completed’ messages,
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// 1 means ‘table entry’, 8 ‘runtime error’ and 9 ‘syntax error’.
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func (b *BIRDClient) exec(cmd string, args ...interface{}) (string, error) {
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if _, err := fmt.Fprintf(b.conn, cmd, args...); err != nil {
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return "", err
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}
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return b.readLine()
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fmt.Fprintln(b.conn)
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return b.readResponse()
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}
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func (b *BIRDClient) readLine() (string, error) {
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if !b.bs.Scan() {
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return "", fmt.Errorf("reading response from bird failed")
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var respCodeRegex = regexp.MustCompile(`^\d{4}[ -]`)
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func (b *BIRDClient) readResponse() (string, error) {
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var resp strings.Builder
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var done bool
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for !done {
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if !b.scanner.Scan() {
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return "", fmt.Errorf("reading response from bird failed: %q", resp.String())
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}
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if err := b.scanner.Err(); err != nil {
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return "", err
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}
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out := b.scanner.Bytes()
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if _, err := resp.Write(out); err != nil {
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return "", err
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}
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if respCodeRegex.Match(out) {
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done = out[4] == ' '
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}
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if !done {
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resp.WriteRune('\n')
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}
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}
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if err := b.bs.Err(); err != nil {
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return "", err
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}
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return b.bs.Text(), nil
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return resp.String(), nil
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}
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@ -0,0 +1,111 @@
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// Copyright (c) 2022 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 chirp
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import (
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"bufio"
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"errors"
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"fmt"
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"net"
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"path/filepath"
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"strings"
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"testing"
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)
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type fakeBIRD struct {
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net.Listener
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protocolsEnabled map[string]bool
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sock string
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}
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func newFakeBIRD(t *testing.T, protocols ...string) *fakeBIRD {
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sock := filepath.Join(t.TempDir(), "sock")
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l, err := net.Listen("unix", sock)
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if err != nil {
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t.Fatal(err)
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}
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pe := make(map[string]bool)
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for _, p := range protocols {
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pe[p] = false
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}
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return &fakeBIRD{
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Listener: l,
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protocolsEnabled: pe,
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sock: sock,
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}
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}
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func (fb *fakeBIRD) listen() error {
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for {
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c, err := fb.Accept()
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if err != nil {
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if errors.Is(err, net.ErrClosed) {
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return nil
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}
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return err
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}
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go fb.handle(c)
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}
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}
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func (fb *fakeBIRD) handle(c net.Conn) {
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fmt.Fprintln(c, "0001 BIRD 2.0.8 ready.")
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sc := bufio.NewScanner(c)
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for sc.Scan() {
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cmd := sc.Text()
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args := strings.Split(cmd, " ")
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switch args[0] {
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case "enable":
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en, ok := fb.protocolsEnabled[args[1]]
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if !ok {
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fmt.Fprintln(c, "9001 syntax error, unexpected CF_SYM_UNDEFINED, expecting CF_SYM_KNOWN or TEXT or ALL")
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} else if en {
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fmt.Fprintf(c, "0010-%s: already enabled\n", args[1])
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} else {
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fmt.Fprintf(c, "0011-%s: enabled\n", args[1])
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}
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fmt.Fprintln(c, "0000 ")
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fb.protocolsEnabled[args[1]] = true
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case "disable":
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en, ok := fb.protocolsEnabled[args[1]]
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if !ok {
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fmt.Fprintln(c, "9001 syntax error, unexpected CF_SYM_UNDEFINED, expecting CF_SYM_KNOWN or TEXT or ALL")
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} else if !en {
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fmt.Fprintf(c, "0008-%s: already disabled\n", args[1])
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} else {
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fmt.Fprintf(c, "0009-%s: disabled\n", args[1])
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}
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fmt.Fprintln(c, "0000 ")
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fb.protocolsEnabled[args[1]] = false
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}
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}
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}
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func TestChirp(t *testing.T) {
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fb := newFakeBIRD(t, "tailscale")
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defer fb.Close()
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go fb.listen()
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c, err := New(fb.sock)
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if err != nil {
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t.Fatal(err)
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}
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if err := c.EnableProtocol("tailscale"); err != nil {
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t.Fatal(err)
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}
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if err := c.EnableProtocol("tailscale"); err != nil {
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t.Fatal(err)
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}
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if err := c.DisableProtocol("tailscale"); err != nil {
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t.Fatal(err)
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}
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if err := c.DisableProtocol("tailscale"); err != nil {
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t.Fatal(err)
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}
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if err := c.EnableProtocol("rando"); err == nil {
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t.Fatalf("enabling %q succeded", "rando")
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}
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if err := c.DisableProtocol("rando"); err == nil {
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t.Fatalf("disabling %q succeded", "rando")
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}
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}
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