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client.go
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client.go
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/*
* Copyright (c) 2013 IBM Corp.
*
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Seth Hoenig
* Allan Stockdill-Mander
* Mike Robertson
*/
// Package mqtt provides an MQTT v3.1.1 client library.
package mqtt
import (
"errors"
"fmt"
"git.eclipse.org/gitroot/paho/org.eclipse.paho.mqtt.golang.git/packets"
"net"
"sync"
"time"
)
// ClientInt is the interface definition for a Client as used by this
// library, the interface is primarily to allow mocking tests.
type ClientInt interface {
IsConnected() bool
Connect() Token
Disconnect(uint)
disconnect()
Publish(string, byte, bool, interface{}) Token
Subscribe(string, byte, MessageHandler) Token
SubscribeMultiple(map[string]byte, MessageHandler) Token
Unsubscribe(...string) Token
}
// Client is an MQTT v3.1.1 client for communicating
// with an MQTT server using non-blocking methods that allow work
// to be done in the background.
// An application may connect to an MQTT server using:
// A plain TCP socket
// A secure SSL/TLS socket
// A websocket
// To enable ensured message delivery at Quality of Service (QoS) levels
// described in the MQTT spec, a message persistence mechanism must be
// used. This is done by providing a type which implements the Store
// interface. For convenience, FileStore and MemoryStore are provided
// implementations that should be sufficient for most use cases. More
// information can be found in their respective documentation.
// Numerous connection options may be specified by configuring a
// and then supplying a ClientOptions type.
type Client struct {
sync.RWMutex
messageIds
conn net.Conn
ibound chan packets.ControlPacket
obound chan *PacketAndToken
oboundP chan *PacketAndToken
msgRouter *router
stopRouter chan bool
incomingPubChan chan *packets.PublishPacket
errors chan error
stop chan struct{}
persist Store
options ClientOptions
lastContact lastcontact
pingOutstanding bool
connected bool
workers sync.WaitGroup
}
// NewClient will create an MQTT v3.1.1 client with all of the options specified
// in the provided ClientOptions. The client must have the Start method called
// on it before it may be used. This is to make sure resources (such as a net
// connection) are created before the application is actually ready.
func NewClient(o *ClientOptions) *Client {
c := &Client{}
c.options = *o
if c.options.Store == nil {
c.options.Store = NewMemoryStore()
}
switch c.options.ProtocolVersion {
case 3, 4:
c.options.protocolVersionExplicit = true
default:
c.options.ProtocolVersion = 4
c.options.protocolVersionExplicit = false
}
c.persist = c.options.Store
c.connected = false
c.messageIds = messageIds{index: make(map[uint16]Token)}
c.msgRouter, c.stopRouter = newRouter()
c.msgRouter.setDefaultHandler(c.options.DefaultPublishHander)
return c
}
// IsConnected returns a bool signifying whether
// the client is connected or not.
func (c *Client) IsConnected() bool {
c.RLock()
defer c.RUnlock()
return c.connected
}
func (c *Client) setConnected(status bool) {
c.Lock()
defer c.Unlock()
c.connected = status
}
//ErrNotConnected is the error returned from function calls that are
//made when the client is not connected to a broker
var ErrNotConnected = errors.New("Not Connected")
// Connect will create a connection to the message broker
// If clean session is false, then a slice will
// be returned containing Receipts for all messages
// that were in-flight at the last disconnect.
// If clean session is true, then any existing client
// state will be removed.
func (c *Client) Connect() Token {
var err error
t := newToken(packets.Connect).(*ConnectToken)
DEBUG.Println(CLI, "Connect()")
go func() {
var rc byte
cm := newConnectMsgFromOptions(&c.options)
for _, broker := range c.options.Servers {
CONN:
DEBUG.Println(CLI, "about to write new connect msg")
c.conn, err = openConnection(broker, &c.options.TLSConfig, c.options.ConnectTimeout)
if err == nil {
DEBUG.Println(CLI, "socket connected to broker")
switch c.options.ProtocolVersion {
case 3:
DEBUG.Println(CLI, "Using MQTT 3.1 protocol")
cm.ProtocolName = "MQIsdp"
cm.ProtocolVersion = 3
default:
DEBUG.Println(CLI, "Using MQTT 3.1.1 protocol")
c.options.ProtocolVersion = 4
cm.ProtocolName = "MQTT"
cm.ProtocolVersion = 4
}
cm.Write(c.conn)
rc = c.connect()
if rc != packets.Accepted {
c.conn.Close()
c.conn = nil
//if the protocol version was explicitly set don't do any fallback
if c.options.protocolVersionExplicit {
ERROR.Println(CLI, "Connecting to", broker, "CONNACK was not CONN_ACCEPTED, but rather", packets.ConnackReturnCodes[rc])
continue
}
if c.options.ProtocolVersion == 4 {
DEBUG.Println(CLI, "Trying reconnect using MQTT 3.1 protocol")
c.options.ProtocolVersion = 3
goto CONN
}
}
break
} else {
ERROR.Println(CLI, err.Error())
WARN.Println(CLI, "failed to connect to broker, trying next")
rc = packets.ErrNetworkError
}
}
if c.conn == nil {
ERROR.Println(CLI, "Failed to connect to a broker")
t.returnCode = rc
if rc != packets.ErrNetworkError {
t.err = packets.ConnErrors[rc]
} else {
t.err = fmt.Errorf("%s : %s", packets.ConnErrors[rc], err)
}
t.flowComplete()
return
}
c.lastContact.update()
c.persist.Open()
c.obound = make(chan *PacketAndToken, 100)
c.oboundP = make(chan *PacketAndToken, 100)
c.ibound = make(chan packets.ControlPacket)
c.errors = make(chan error)
c.stop = make(chan struct{})
c.incomingPubChan = make(chan *packets.PublishPacket, 100)
c.msgRouter.matchAndDispatch(c.incomingPubChan, c.options.Order, c)
c.workers.Add(1)
go outgoing(c)
go alllogic(c)
c.connected = true
DEBUG.Println(CLI, "client is connected")
if c.options.OnConnect != nil {
go c.options.OnConnect(c)
}
if c.options.KeepAlive != 0 {
c.workers.Add(1)
go keepalive(c)
}
// Take care of any messages in the store
//var leftovers []Receipt
if c.options.CleanSession == false {
//leftovers = c.resume()
} else {
c.persist.Reset()
}
// Do not start incoming until resume has completed
c.workers.Add(1)
go incoming(c)
DEBUG.Println(CLI, "exit startClient")
t.flowComplete()
}()
return t
}
// internal function used to reconnect the client when it loses its connection
func (c *Client) reconnect() {
DEBUG.Println(CLI, "enter reconnect")
var rc byte = 1
var sleep uint = 1
var err error
for rc != 0 {
cm := newConnectMsgFromOptions(&c.options)
for _, broker := range c.options.Servers {
CONN:
DEBUG.Println(CLI, "about to write new connect msg")
c.conn, err = openConnection(broker, &c.options.TLSConfig, c.options.ConnectTimeout)
if err == nil {
DEBUG.Println(CLI, "socket connected to broker")
switch c.options.ProtocolVersion {
case 3:
DEBUG.Println(CLI, "Using MQTT 3.1 protocol")
cm.ProtocolName = "MQIsdp"
cm.ProtocolVersion = 3
default:
DEBUG.Println(CLI, "Using MQTT 3.1.1 protocol")
c.options.ProtocolVersion = 4
cm.ProtocolName = "MQTT"
cm.ProtocolVersion = 4
}
cm.Write(c.conn)
rc = c.connect()
if rc != packets.Accepted {
c.conn.Close()
c.conn = nil
//if the protocol version was explicitly set don't do any fallback
if c.options.protocolVersionExplicit {
ERROR.Println(CLI, "Connecting to", broker, "CONNACK was not Accepted, but rather", packets.ConnackReturnCodes[rc])
continue
}
if c.options.ProtocolVersion == 4 {
DEBUG.Println(CLI, "Trying reconnect using MQTT 3.1 protocol")
c.options.ProtocolVersion = 3
goto CONN
}
}
break
} else {
ERROR.Println(CLI, err.Error())
WARN.Println(CLI, "failed to connect to broker, trying next")
rc = packets.ErrNetworkError
}
}
if rc != 0 {
DEBUG.Println(CLI, "Reconnect failed, sleeping for", sleep, "seconds")
time.Sleep(time.Duration(sleep) * time.Second)
if sleep <= uint(c.options.MaxReconnectInterval.Seconds()) {
sleep *= 2
}
}
}
c.lastContact.update()
c.stop = make(chan struct{})
c.workers.Add(1)
go outgoing(c)
go alllogic(c)
c.setConnected(true)
DEBUG.Println(CLI, "client is reconnected")
if c.options.OnConnect != nil {
go c.options.OnConnect(c)
}
if c.options.KeepAlive != 0 {
c.workers.Add(1)
go keepalive(c)
}
c.workers.Add(1)
go incoming(c)
}
// This function is only used for receiving a connack
// when the connection is first started.
// This prevents receiving incoming data while resume
// is in progress if clean session is false.
func (c *Client) connect() byte {
DEBUG.Println(NET, "connect started")
ca, err := packets.ReadPacket(c.conn)
if err != nil {
ERROR.Println(NET, "connect got error", err)
//c.errors <- err
return packets.ErrNetworkError
}
msg := ca.(*packets.ConnackPacket)
if msg == nil || msg.FixedHeader.MessageType != packets.Connack {
ERROR.Println(NET, "received msg that was nil or not CONNACK")
} else {
DEBUG.Println(NET, "received connack")
}
return msg.ReturnCode
}
// Disconnect will end the connection with the server, but not before waiting
// the specified number of milliseconds to wait for existing work to be
// completed.
func (c *Client) Disconnect(quiesce uint) {
if !c.IsConnected() {
WARN.Println(CLI, "already disconnected")
return
}
DEBUG.Println(CLI, "disconnecting")
c.setConnected(false)
dm := packets.NewControlPacket(packets.Disconnect).(*packets.DisconnectPacket)
dt := newToken(packets.Disconnect)
c.oboundP <- &PacketAndToken{p: dm, t: dt}
// wait for work to finish, or quiesce time consumed
dt.WaitTimeout(time.Duration(quiesce) * time.Millisecond)
c.disconnect()
}
// ForceDisconnect will end the connection with the mqtt broker immediately.
func (c *Client) forceDisconnect() {
if !c.IsConnected() {
WARN.Println(CLI, "already disconnected")
return
}
c.setConnected(false)
c.conn.Close()
DEBUG.Println(CLI, "forcefully disconnecting")
c.disconnect()
}
func (c *Client) internalConnLost(err error) {
close(c.stop)
c.conn.Close()
c.workers.Wait()
if c.IsConnected() {
if c.options.OnConnectionLost != nil {
go c.options.OnConnectionLost(c, err)
}
if c.options.AutoReconnect {
go c.reconnect()
} else {
c.setConnected(false)
}
}
}
func (c *Client) disconnect() {
select {
case <-c.stop:
//someone else has already closed the channel, must be error
default:
close(c.stop)
}
c.conn.Close()
c.workers.Wait()
close(c.stopRouter)
DEBUG.Println(CLI, "disconnected")
c.persist.Close()
}
// Publish will publish a message with the specified QoS
// and content to the specified topic.
// Returns a read only channel used to track
// the delivery of the message.
func (c *Client) Publish(topic string, qos byte, retained bool, payload interface{}) Token {
token := newToken(packets.Publish).(*PublishToken)
DEBUG.Println(CLI, "enter Publish")
if !c.IsConnected() {
token.err = ErrNotConnected
token.flowComplete()
return token
}
pub := packets.NewControlPacket(packets.Publish).(*packets.PublishPacket)
pub.Qos = qos
pub.TopicName = topic
pub.Retain = retained
switch payload.(type) {
case string:
pub.Payload = []byte(payload.(string))
case []byte:
pub.Payload = payload.([]byte)
default:
token.err = errors.New("Unknown payload type")
token.flowComplete()
return token
}
DEBUG.Println(CLI, "sending publish message, topic:", topic)
c.obound <- &PacketAndToken{p: pub, t: token}
return token
}
// Subscribe starts a new subscription. Provide a MessageHandler to be executed when
// a message is published on the topic provided.
func (c *Client) Subscribe(topic string, qos byte, callback MessageHandler) Token {
token := newToken(packets.Subscribe).(*SubscribeToken)
DEBUG.Println(CLI, "enter Subscribe")
if !c.IsConnected() {
token.err = ErrNotConnected
token.flowComplete()
return token
}
sub := packets.NewControlPacket(packets.Subscribe).(*packets.SubscribePacket)
if err := validateTopicAndQos(topic, qos); err != nil {
token.err = err
return token
}
sub.Topics = append(sub.Topics, topic)
sub.Qoss = append(sub.Qoss, qos)
DEBUG.Println(sub.String())
if callback != nil {
c.msgRouter.addRoute(topic, callback)
}
token.subs = append(token.subs, topic)
c.oboundP <- &PacketAndToken{p: sub, t: token}
DEBUG.Println(CLI, "exit Subscribe")
return token
}
// SubscribeMultiple starts a new subscription for multiple topics. Provide a MessageHandler to
// be executed when a message is published on one of the topics provided.
func (c *Client) SubscribeMultiple(filters map[string]byte, callback MessageHandler) Token {
var err error
token := newToken(packets.Subscribe).(*SubscribeToken)
DEBUG.Println(CLI, "enter SubscribeMultiple")
if !c.IsConnected() {
token.err = ErrNotConnected
token.flowComplete()
return token
}
sub := packets.NewControlPacket(packets.Subscribe).(*packets.SubscribePacket)
if sub.Topics, sub.Qoss, err = validateSubscribeMap(filters); err != nil {
token.err = err
return token
}
if callback != nil {
for topic := range filters {
c.msgRouter.addRoute(topic, callback)
}
}
token.subs = make([]string, len(sub.Topics))
copy(token.subs, sub.Topics)
c.oboundP <- &PacketAndToken{p: sub, t: token}
DEBUG.Println(CLI, "exit SubscribeMultiple")
return token
}
// Unsubscribe will end the subscription from each of the topics provided.
// Messages published to those topics from other clients will no longer be
// received.
func (c *Client) Unsubscribe(topics ...string) Token {
token := newToken(packets.Unsubscribe).(*UnsubscribeToken)
DEBUG.Println(CLI, "enter Unsubscribe")
if !c.IsConnected() {
token.err = ErrNotConnected
token.flowComplete()
return token
}
unsub := packets.NewControlPacket(packets.Unsubscribe).(*packets.UnsubscribePacket)
unsub.Topics = make([]string, len(topics))
copy(unsub.Topics, topics)
c.oboundP <- &PacketAndToken{p: unsub, t: token}
for _, topic := range topics {
c.msgRouter.deleteRoute(topic)
}
DEBUG.Println(CLI, "exit Unsubscribe")
return token
}
//DefaultConnectionLostHandler is a definition of a function that simply
//reports to the DEBUG log the reason for the client losing a connection.
func DefaultConnectionLostHandler(client *Client, reason error) {
DEBUG.Println("Connection lost:", reason.Error())
}