tailscale/chirp/chirp.go
Maisem Ali fd4838dc57 wgengine/userspace: add support to automatically enable/disable the tailscale
protocol in BIRD, when the node is a primary subnet router as determined
by control.

Signed-off-by: Maisem Ali <maisem@tailscale.com>
2021-08-30 10:18:05 -07:00

84 lines
2.2 KiB
Go

// Copyright (c) 2021 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 chirp implements a client to communicate with the BIRD Internet
// Routing Daemon.
package chirp
import (
"bufio"
"fmt"
"net"
"strings"
)
// New creates a BIRDClient.
func New(socket string) (*BIRDClient, error) {
conn, err := net.Dial("unix", socket)
if err != nil {
return nil, fmt.Errorf("failed to connect to BIRD: %w", err)
}
b := &BIRDClient{socket: socket, conn: conn, bs: bufio.NewScanner(conn)}
// Read and discard the first line as that is the welcome message.
if _, err := b.readLine(); err != nil {
return nil, err
}
return b, nil
}
// BIRDClient handles communication with the BIRD Internet Routing Daemon.
type BIRDClient struct {
socket string
conn net.Conn
bs *bufio.Scanner
}
// Close closes the underlying connection to BIRD.
func (b *BIRDClient) Close() error { return b.conn.Close() }
// DisableProtocol disables the provided protocol.
func (b *BIRDClient) DisableProtocol(protocol string) error {
out, err := b.exec("disable %s\n", protocol)
if err != nil {
return err
}
if strings.Contains(out, fmt.Sprintf("%s: already disabled", protocol)) {
return nil
} else if strings.Contains(out, fmt.Sprintf("%s: disabled", protocol)) {
return nil
}
return fmt.Errorf("failed to disable %s: %v", protocol, out)
}
// EnableProtocol enables the provided protocol.
func (b *BIRDClient) EnableProtocol(protocol string) error {
out, err := b.exec("enable %s\n", protocol)
if err != nil {
return err
}
if strings.Contains(out, fmt.Sprintf("%s: already enabled", protocol)) {
return nil
} else if strings.Contains(out, fmt.Sprintf("%s: enabled", protocol)) {
return nil
}
return fmt.Errorf("failed to enable %s: %v", protocol, out)
}
func (b *BIRDClient) exec(cmd string, args ...interface{}) (string, error) {
if _, err := fmt.Fprintf(b.conn, cmd, args...); err != nil {
return "", err
}
return b.readLine()
}
func (b *BIRDClient) readLine() (string, error) {
if !b.bs.Scan() {
return "", fmt.Errorf("reading response from bird failed")
}
if err := b.bs.Err(); err != nil {
return "", err
}
return b.bs.Text(), nil
}