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client.rb
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client.rb
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autoload :OpenSSL, 'openssl'
autoload :URI, 'uri'
# Client class for talking to an MQTT server
class MQTT::Client
# Hostname of the remote server
attr_accessor :host
# Port number of the remote server
attr_accessor :port
# The version number of the MQTT protocol to use (default 3.1.1)
attr_accessor :version
# Set to true to enable SSL/TLS encrypted communication
#
# Set to a symbol to use a specific variant of SSL/TLS.
# Allowed values include:
#
# @example Using TLS 1.0
# client = Client.new('mqtt.example.com', :ssl => :TLSv1)
# @see OpenSSL::SSL::SSLContext::METHODS
attr_accessor :ssl
# Time (in seconds) between pings to remote server (default is 15 seconds)
attr_accessor :keep_alive
# Set the 'Clean Session' flag when connecting? (default is true)
attr_accessor :clean_session
# Client Identifier
attr_accessor :client_id
# Number of seconds to wait for acknowledgement packets (default is 5 seconds)
attr_accessor :ack_timeout
# Username to authenticate to the server with
attr_accessor :username
# Password to authenticate to the server with
attr_accessor :password
# The topic that the Will message is published to
attr_accessor :will_topic
# Contents of message that is sent by server when client disconnect
attr_accessor :will_payload
# The QoS level of the will message sent by the server
attr_accessor :will_qos
# If the Will message should be retain by the server after it is sent
attr_accessor :will_retain
# Last ping response time
attr_reader :last_ping_response
# Timeout between select polls (in seconds)
SELECT_TIMEOUT = 0.5
# Default attribute values
ATTR_DEFAULTS = {
:host => nil,
:port => nil,
:version => '3.1.1',
:keep_alive => 15,
:clean_session => true,
:client_id => nil,
:ack_timeout => 5,
:username => nil,
:password => nil,
:will_topic => nil,
:will_payload => nil,
:will_qos => 0,
:will_retain => false,
:ssl => false
}
# Create and connect a new MQTT Client
#
# Accepts the same arguments as creating a new client.
# If a block is given, then it will be executed before disconnecting again.
#
# Example:
# MQTT::Client.connect('myserver.example.com') do |client|
# # do stuff here
# end
#
def self.connect(*args, &block)
client = MQTT::Client.new(*args)
client.connect(&block)
return client
end
# Generate a random client identifier
# (using the characters 0-9 and a-z)
def self.generate_client_id(prefix='ruby', length=16)
str = prefix.dup
length.times do
num = rand(36)
if (num<10)
# Number
num += 48
else
# Letter
num += 87
end
str += num.chr
end
return str
end
# Create a new MQTT Client instance
#
# Accepts one of the following:
# - a URI that uses the MQTT scheme
# - a hostname and port
# - a Hash containing attributes to be set on the new instance
#
# If no arguments are given then the method will look for a URI
# in the MQTT_SERVER environment variable.
#
# Examples:
# client = MQTT::Client.new
# client = MQTT::Client.new('mqtt://myserver.example.com')
# client = MQTT::Client.new('mqtt://user:pass@myserver.example.com')
# client = MQTT::Client.new('myserver.example.com')
# client = MQTT::Client.new('myserver.example.com', 18830)
# client = MQTT::Client.new(:host => 'myserver.example.com')
# client = MQTT::Client.new(:host => 'myserver.example.com', :keep_alive => 30)
#
def initialize(*args)
if args.last.is_a?(Hash)
attr = args.pop
else
attr = {}
end
if args.length == 0
if ENV['MQTT_SERVER']
attr.merge!(parse_uri(ENV['MQTT_SERVER']))
end
end
if args.length >= 1
case args[0]
when URI
attr.merge!(parse_uri(args[0]))
when %r|^mqtts?://|
attr.merge!(parse_uri(args[0]))
else
attr.merge!(:host => args[0])
end
end
if args.length >= 2
attr.merge!(:port => args[1]) unless args[1].nil?
end
if args.length >= 3
raise ArgumentError, "Unsupported number of arguments"
end
# Merge arguments with default values for attributes
ATTR_DEFAULTS.merge(attr).each_pair do |k,v|
self.send("#{k}=", v)
end
# Set a default port number
if @port.nil?
@port = @ssl ? MQTT::DEFAULT_SSL_PORT : MQTT::DEFAULT_PORT
end
# Initialise private instance variables
@last_ping_request = Time.now
@last_ping_response = Time.now
@socket = nil
@read_queue = Queue.new
@pubacks = {}
@read_thread = nil
@write_semaphore = Mutex.new
@pubacks_semaphore = Mutex.new
end
# Get the OpenSSL context, that is used if SSL/TLS is enabled
def ssl_context
@ssl_context ||= OpenSSL::SSL::SSLContext.new
end
# Set a path to a file containing a PEM-format client certificate
def cert_file=(path)
self.cert = File.read(path)
end
# PEM-format client certificate
def cert=(cert)
ssl_context.cert = OpenSSL::X509::Certificate.new(cert)
end
# Set a path to a file containing a PEM-format client private key
def key_file=(*args)
path, passphrase = args.flatten
ssl_context.key = OpenSSL::PKey::RSA.new(File.open(path), passphrase)
end
# Set to a PEM-format client private key
def key=(*args)
cert, passphrase = args.flatten
ssl_context.key = OpenSSL::PKey::RSA.new(cert, passphrase)
end
# Set a path to a file containing a PEM-format CA certificate and enable peer verification
def ca_file=(path)
ssl_context.ca_file = path
unless path.nil?
ssl_context.verify_mode = OpenSSL::SSL::VERIFY_PEER
end
end
# Set the Will for the client
#
# The will is a message that will be delivered by the server when the client dies.
# The Will must be set before establishing a connection to the server
def set_will(topic, payload, retain=false, qos=0)
self.will_topic = topic
self.will_payload = payload
self.will_retain = retain
self.will_qos = qos
end
# Connect to the MQTT server
# If a block is given, then yield to that block and then disconnect again.
def connect(clientid=nil)
unless clientid.nil?
@client_id = clientid
end
if @client_id.nil? or @client_id.empty?
if @clean_session
if @version == '3.1.0'
# Empty client id is not allowed for version 3.1.0
@client_id = MQTT::Client.generate_client_id
end
else
raise 'Must provide a client_id if clean_session is set to false'
end
end
if @host.nil?
raise 'No MQTT server host set when attempting to connect'
end
if not connected?
# Create network socket
tcp_socket = TCPSocket.new(@host, @port)
if @ssl
# Set the protocol version
if @ssl.is_a?(Symbol)
ssl_context.ssl_version = @ssl
end
@socket = OpenSSL::SSL::SSLSocket.new(tcp_socket, ssl_context)
@socket.sync_close = true
# Set hostname on secure socket for Server Name Indication (SNI)
if @socket.respond_to?(:hostname=)
@socket.hostname = @host
end
@socket.connect
else
@socket = tcp_socket
end
# Construct a connect packet
packet = MQTT::Packet::Connect.new(
:version => @version,
:clean_session => @clean_session,
:keep_alive => @keep_alive,
:client_id => @client_id,
:username => @username,
:password => @password,
:will_topic => @will_topic,
:will_payload => @will_payload,
:will_qos => @will_qos,
:will_retain => @will_retain
)
# Send packet
send_packet(packet)
# Receive response
receive_connack
# Start packet reading thread
@read_thread = Thread.new(Thread.current) do |parent|
Thread.current[:parent] = parent
while connected? do
receive_packet
end
end
end
# If a block is given, then yield and disconnect
if block_given?
begin
yield(self)
ensure
disconnect
end
end
end
# Disconnect from the MQTT server.
# If you don't want to say goodbye to the server, set send_msg to false.
def disconnect(send_msg=true)
# Stop reading packets from the socket first
@read_thread.kill if @read_thread and @read_thread.alive?
@read_thread = nil
# Close the socket if it is open
if connected?
if send_msg
packet = MQTT::Packet::Disconnect.new
send_packet(packet)
end
@socket.close unless @socket.nil?
@socket = nil
end
end
# Checks whether the client is connected to the server.
def connected?
(not @socket.nil?) and (not @socket.closed?)
end
# Publish a message on a particular topic to the MQTT server.
def publish(topic, payload='', retain=false, qos=0)
raise ArgumentError.new("Topic name cannot be nil") if topic.nil?
raise ArgumentError.new("Topic name cannot be empty") if topic.empty?
packet = MQTT::Packet::Publish.new(
:id => next_packet_id,
:qos => qos,
:retain => retain,
:topic => topic,
:payload => payload
)
# Send the packet
res = send_packet(packet)
if packet.qos > 0
Timeout.timeout(@ack_timeout) do
while connected? do
@pubacks_semaphore.synchronize do
return res if @pubacks.delete(packet.id)
end
# FIXME: make threads communicate with each other, instead of polling
# (using a pipe and select ?)
sleep 0.01
end
end
return -1
end
end
# Send a subscribe message for one or more topics on the MQTT server.
# The topics parameter should be one of the following:
# * String: subscribe to one topic with QoS 0
# * Array: subscribe to multiple topics with QoS 0
# * Hash: subscribe to multiple topics where the key is the topic and the value is the QoS level
#
# For example:
# client.subscribe( 'a/b' )
# client.subscribe( 'a/b', 'c/d' )
# client.subscribe( ['a/b',0], ['c/d',1] )
# client.subscribe( 'a/b' => 0, 'c/d' => 1 )
#
def subscribe(*topics)
packet = MQTT::Packet::Subscribe.new(
:id => next_packet_id,
:topics => topics
)
send_packet(packet)
end
# Return the next message received from the MQTT server.
# An optional topic can be given to subscribe to.
#
# The method either returns the topic and message as an array:
# topic,message = client.get
#
# Or can be used with a block to keep processing messages:
# client.get('test') do |topic,payload|
# # Do stuff here
# end
#
def get(topic=nil, options={})
if block_given?
get_packet(topic) do |packet|
yield(packet.topic, packet.payload) unless packet.retain && options[:omit_retained]
end
else
loop do
# Wait for one packet to be available
packet = get_packet(topic)
return packet.topic, packet.payload unless packet.retain && options[:omit_retained]
end
end
end
# Return the next packet object received from the MQTT server.
# An optional topic can be given to subscribe to.
#
# The method either returns a single packet:
# packet = client.get_packet
# puts packet.topic
#
# Or can be used with a block to keep processing messages:
# client.get_packet('test') do |packet|
# # Do stuff here
# puts packet.topic
# end
#
def get_packet(topic=nil)
# Subscribe to a topic, if an argument is given
subscribe(topic) unless topic.nil?
if block_given?
# Loop forever!
loop do
packet = @read_queue.pop
yield(packet)
puback_packet(packet) if packet.qos > 0
end
else
# Wait for one packet to be available
packet = @read_queue.pop
puback_packet(packet) if packet.qos > 0
return packet
end
end
# Returns true if the incoming message queue is empty.
def queue_empty?
@read_queue.empty?
end
# Returns the length of the incoming message queue.
def queue_length
@read_queue.length
end
# Send a unsubscribe message for one or more topics on the MQTT server
def unsubscribe(*topics)
if topics.is_a?(Enumerable) and topics.count == 1
topics = topics.first
end
packet = MQTT::Packet::Unsubscribe.new(
:topics => topics,
:id => next_packet_id
)
send_packet(packet)
end
private
# Try to read a packet from the server
# Also sends keep-alive ping packets.
def receive_packet
begin
# Poll socket - is there data waiting?
result = IO.select([@socket], [], [], SELECT_TIMEOUT)
unless result.nil?
# Yes - read in the packet
packet = MQTT::Packet.read(@socket)
handle_packet packet
end
keep_alive!
# Pass exceptions up to parent thread
rescue Exception => exp
unless @socket.nil?
@socket.close
@socket = nil
end
Thread.current[:parent].raise(exp)
end
end
def handle_packet(packet)
if packet.class == MQTT::Packet::Publish
# Add to queue
@read_queue.push(packet)
elsif packet.class == MQTT::Packet::Pingresp
@last_ping_response = Time.now
elsif packet.class == MQTT::Packet::Puback
@pubacks_semaphore.synchronize do
@pubacks[packet.id] = packet
end
end
# Ignore all other packets
# FIXME: implement responses for QoS 2
end
def keep_alive!
if @keep_alive > 0 && connected?
response_timeout = (@keep_alive * 1.5).ceil
if Time.now >= @last_ping_request + @keep_alive
packet = MQTT::Packet::Pingreq.new
send_packet(packet)
@last_ping_request = Time.now
elsif Time.now > @last_ping_response + response_timeout
raise MQTT::ProtocolException.new(
"No Ping Response received for #{response_timeout} seconds"
)
end
end
end
def puback_packet(packet)
send_packet(MQTT::Packet::Puback.new :id => packet.id)
end
# Read and check a connection acknowledgement packet
def receive_connack
Timeout.timeout(@ack_timeout) do
packet = MQTT::Packet.read(@socket)
if packet.class != MQTT::Packet::Connack
raise MQTT::ProtocolException.new(
"Response wasn't a connection acknowledgement: #{packet.class}"
)
end
# Check the return code
if packet.return_code != 0x00
# 3.2.2.3 If a server sends a CONNACK packet containing a non-zero
# return code it MUST then close the Network Connection
@socket.close
raise MQTT::ProtocolException.new(packet.return_msg)
end
end
end
# Send a packet to server
def send_packet(data)
# Raise exception if we aren't connected
raise MQTT::NotConnectedException if not connected?
# Only allow one thread to write to socket at a time
@write_semaphore.synchronize do
@socket.write(data.to_s)
end
end
private
def parse_uri(uri)
uri = URI.parse(uri) unless uri.is_a?(URI)
if uri.scheme == 'mqtt'
ssl = false
elsif uri.scheme == 'mqtts'
ssl = true
else
raise "Only the mqtt:// and mqtts:// schemes are supported"
end
{
:host => uri.host,
:port => uri.port || nil,
:username => uri.user ? URI.unescape(uri.user) : nil,
:password => uri.password ? URI.unescape(uri.password) : nil,
:ssl => ssl
}
end
def next_packet_id
@last_packet_id = ( @last_packet_id || 0 ).next
end
# ---- Deprecated attributes and methods ---- #
public
# @deprecated Please use {#host} instead
def remote_host
host
end
# @deprecated Please use {#host=} instead
def remote_host=(args)
self.host = args
end
# @deprecated Please use {#port} instead
def remote_port
port
end
# @deprecated Please use {#port=} instead
def remote_port=(args)
self.port = args
end
end