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/**
* Standalone signaling server for the Nextcloud Spreed app.
* Copyright (C) 2017 struktur AG
*
* @author Joachim Bauch <bauch@struktur.de>
*
* @license GNU AGPL version 3 or any later version
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package signaling
import (
"encoding/base64"
"fmt"
"log"
"os"
"os/signal"
"time"
"github.com/nats-io/nats.go"
)
const (
initialConnectInterval = time.Second
maxConnectInterval = 8 * time.Second
)
type NatsMessage struct {
Type string `json:"type"`
Message *ServerMessage `json:"message,omitempty"`
Room *BackendServerRoomRequest `json:"room,omitempty"`
Permissions []Permission `json:"permissions,omitempty"`
}
type NatsSubscription interface {
Unsubscribe() error
}
type NatsClient interface {
Subscribe(subject string, ch chan *nats.Msg) (NatsSubscription, error)
Request(subject string, data []byte, timeout time.Duration) (*nats.Msg, error)
Publish(subject string, message interface{}) error
PublishNats(subject string, message *NatsMessage) error
PublishMessage(subject string, message *ServerMessage) error
PublishBackendServerRoomRequest(subject string, message *BackendServerRoomRequest) error
Decode(msg *nats.Msg, v interface{}) error
}
// The NATS client doesn't work if a subject contains spaces. As the room id
// can have an arbitrary format, we need to make sure the subject is valid.
// See "https://github.com/nats-io/nats.js/issues/158" for a similar report.
func GetEncodedSubject(prefix string, suffix string) string {
return prefix + "." + base64.StdEncoding.EncodeToString([]byte(suffix))
}
type natsClient struct {
nc *nats.Conn
conn *nats.EncodedConn
}
func NewNatsClient(url string) (NatsClient, error) {
if url == ":loopback:" {
log.Println("No NATS url configured, using internal loopback client")
return NewLoopbackNatsClient()
}
client := &natsClient{}
var err error
client.nc, err = nats.Connect(url,
nats.ClosedHandler(client.onClosed),
nats.DisconnectHandler(client.onDisconnected),
nats.ReconnectHandler(client.onReconnected))
interrupt := make(chan os.Signal, 1)
signal.Notify(interrupt, os.Interrupt)
defer signal.Stop(interrupt)
delay := initialConnectInterval
timer := time.NewTimer(delay)
// The initial connect must succeed, so we retry in the case of an error.
for err != nil {
log.Printf("Could not create connection (%s), will retry in %s", err, delay)
timer.Reset(delay)
select {
case <-interrupt:
return nil, fmt.Errorf("interrupted")
case <-timer.C:
// Retry connection
delay = delay * 2
if delay > maxConnectInterval {
delay = maxConnectInterval
}
}
client.nc, err = nats.Connect(url)
}
log.Printf("Connection established to %s (%s)\n", client.nc.ConnectedUrl(), client.nc.ConnectedServerId())
// All communication will be JSON based.
client.conn, _ = nats.NewEncodedConn(client.nc, nats.JSON_ENCODER)
return client, nil
}
func (c *natsClient) onClosed(conn *nats.Conn) {
log.Println("NATS client closed", conn.LastError())
}
func (c *natsClient) onDisconnected(conn *nats.Conn) {
log.Println("NATS client disconnected")
}
func (c *natsClient) onReconnected(conn *nats.Conn) {
log.Printf("NATS client reconnected to %s (%s)\n", conn.ConnectedUrl(), conn.ConnectedServerId())
}
func (c *natsClient) Subscribe(subject string, ch chan *nats.Msg) (NatsSubscription, error) {
return c.nc.ChanSubscribe(subject, ch)
}
func (c *natsClient) Request(subject string, data []byte, timeout time.Duration) (*nats.Msg, error) {
return c.nc.Request(subject, data, timeout)
}
func (c *natsClient) Publish(subject string, message interface{}) error {
return c.conn.Publish(subject, message)
}
func (c *natsClient) PublishNats(subject string, message *NatsMessage) error {
return c.Publish(subject, message)
}
func (c *natsClient) PublishMessage(subject string, message *ServerMessage) error {
msg := &NatsMessage{
Type: "message",
Message: message,
}
return c.PublishNats(subject, msg)
}
func (c *natsClient) PublishBackendServerRoomRequest(subject string, message *BackendServerRoomRequest) error {
msg := &NatsMessage{
Type: "room",
Room: message,
}
return c.PublishNats(subject, msg)
}
func (c *natsClient) Decode(msg *nats.Msg, v interface{}) error {
return c.conn.Enc.Decode(msg.Subject, msg.Data, v)
}