class CoAP(object):
"""
Implementation of the CoAP server
"""
def __init__(self, server_address, qos = 0,multicast=False, starting_mid=None, sock=None, cb_ignore_listen_exception=None):
"""
Initialize the server.
:param server_address: Server address for incoming connections
:param multicast: if the ip is a multicast address
:param starting_mid: used for testing purposes
:param sock: if a socket has been created externally, it can be used directly
:param cb_ignore_listen_exception: Callback function to handle exception raised during the socket listen operation
"""
self.stopped = threading.Event()
self.stopped.clear()
self.to_be_stopped = []
self.purge = threading.Thread(target=self.purge)
self.purge.start()
self._messageLayer = MessageLayer(starting_mid)
self._blockLayer = BlockLayer()
self._observeLayer = ObserveLayer()
self._requestLayer = RequestLayer(self)
self.resourceLayer = ResourceLayer(self)
# Resource directory
root = Resource('root', self, visible=False, observable=False, allow_children=False)
root.path = '/'
self.root = Tree()
self.root["/"] = root
self._serializer = None
self.server_address = server_address
self.multicast = multicast
self._cb_ignore_listen_exception = cb_ignore_listen_exception
addrinfo = socket.getaddrinfo(self.server_address[0], None)[0]
#attributes used for pub-sub
self._qos = qos
self._blocking_read = True
if sock is not None:
# Use given socket, could be a DTLS socket
self._socket = sock
elif self.multicast: # pragma: no cover
# Create a socket
# self._socket.setsockopt(socket.SOL_IP, socket.IP_MULTICAST_TTL, 255)
# self._socket.setsockopt(socket.SOL_IP, socket.IP_MULTICAST_LOOP, 1)
# Join group
if addrinfo[0] == socket.AF_INET: # IPv4
self._socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.IPPROTO_UDP)
self._socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
self._socket.bind(('', self.server_address[1]))
mreq = struct.pack("4sl", socket.inet_aton(defines.ALL_COAP_NODES), socket.INADDR_ANY)
self._socket.setsockopt(socket.IPPROTO_IP, socket.IP_ADD_MEMBERSHIP, mreq)
else:
self._socket = socket.socket(socket.AF_INET6, socket.SOCK_DGRAM, socket.IPPROTO_UDP)
# Allow multiple copies of this program on one machine
# (not strictly needed)
self._socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
self._socket.bind((defines.ALL_COAP_NODES_IPV6, self.server_address[1]))
addrinfo_multicast = socket.getaddrinfo(defines.ALL_COAP_NODES_IPV6, 5683)[0]
group_bin = socket.inet_pton(socket.AF_INET6, addrinfo_multicast[4][0])
mreq = group_bin + struct.pack('@I', 0)
self._socket.setsockopt(socket.IPPROTO_IPV6, socket.IPV6_JOIN_GROUP, mreq)
self._unicast_socket = socket.socket(socket.AF_INET6, socket.SOCK_DGRAM)
self._unicast_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
self._unicast_socket.bind(self.server_address)
else:
if addrinfo[0] == socket.AF_INET: # IPv4
self._socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
self._socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
else:
self._socket = socket.socket(socket.AF_INET6, socket.SOCK_DGRAM)
self._socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
self._socket.bind(self.server_address)
def purge(self):
"""
Clean old transactions and old resources (max-age expired)
"""
while not self.stopped.isSet():
self.stopped.wait(timeout=defines.EXCHANGE_LIFETIME)
#self.stopped.wait(timeout=5)
self._messageLayer.purge()
self.resourceLayer.purge()
def listen(self, timeout=10):
"""
Listen for incoming messages. Timeout is used to check if the server must be switched off.
:param timeout: Socket Timeout in seconds
"""
self._socket.settimeout(float(timeout))
while not self.stopped.isSet():
try:
data, client_address = self._socket.recvfrom(4096)
if len(client_address) > 2:
client_address = (client_address[0], client_address[1])
except socket.timeout:
continue
except Exception as e:
if self._cb_ignore_listen_exception is not None and isinstance(self._cb_ignore_listen_exception, collections.Callable):
if self._cb_ignore_listen_exception(e, self):
continue
raise
try:
serializer = Serializer()
message = serializer.deserialize(data, client_address)
if isinstance(message, int):
logger.error("receive_datagram - BAD REQUEST")
rst = Message()
rst.destination = client_address
rst.type = defines.Types["RST"]
rst.code = message
rst.mid = self._messageLayer.fetch_mid()
self.send_datagram(rst)
continue
logger.debug("receive_datagram - " + str(message))
if isinstance(message, Request):
transaction = self._messageLayer.receive_request(message)
if transaction.request.duplicated and transaction.completed:
logger.debug("message duplicated, transaction completed")
if transaction.response is not None:
self.send_datagram(transaction.response)
continue
elif transaction.request.duplicated and not transaction.completed:
logger.debug("message duplicated, transaction NOT completed")
self._send_ack(transaction)
continue
args = (transaction, )
t = threading.Thread(target=self.receive_request, args=args)
t.start()
# self.receive_datagram(data, client_address)
elif isinstance(message, Response):
logger.error("Received response from %s", message.source)
else: # is Message
transaction = self._messageLayer.receive_empty(message)
if transaction is not None:
with transaction:
self._blockLayer.receive_empty(message, transaction)
self._observeLayer.receive_empty(message, transaction)
except RuntimeError:
logger.exception("Exception with Executor")
self._socket.close()
def close(self):
"""
Stop the server.
"""
logger.info("Stop server")
self.stopped.set()
for event in self.to_be_stopped:
event.set()
def receive_request(self, transaction):
"""
Handle requests coming from the udp socket.
:param transaction: the transaction created to manage the request
"""
with transaction:
transaction.separate_timer = self._start_separate_timer(transaction)
self._blockLayer.receive_request(transaction)
if transaction.block_transfer:
self._stop_separate_timer(transaction.separate_timer)
self._messageLayer.send_response(transaction)
self.send_datagram(transaction.response)
return
self._observeLayer.receive_request(transaction)
self._requestLayer.receive_request(transaction)
self._observeLayer.send_response(transaction)
self._blockLayer.send_response(transaction)
self._stop_separate_timer(transaction.separate_timer)
self._messageLayer.send_response(transaction)
if transaction.response is not None:
if transaction.response.type == defines.Types["CON"]:
self._start_retransmission(transaction, transaction.response)
self.send_datagram(transaction.response)
if transaction.resource is not None:
if transaction.resource.changed:
#if transaction.response.code == defines.Codes.CHANGED.number:
self.notify(transaction.resource)
transaction.resource.changed = False
elif transaction.resource.deleted:
#if transaction.response.code == defines.Codes.DELETED.number:
self.notify(transaction.resource, True)
transaction.resource.deleted = False
def send_datagram(self, message):
"""
Send a message through the udp socket.
:type message: Message
:param message: the message to send
"""
if not self.stopped.isSet():
host, port = message.destination
logger.debug("send_datagram - " + str(message))
serializer = Serializer()
message = serializer.serialize(message)
self._socket.sendto(message, (host, port))
def add_resource(self, path, resource):
"""
Helper function to add resources to the resource directory during server initialization.
:param path: the path for the new created resource
:type resource: Resource
:param resource: the resource to be added
"""
assert isinstance(resource, Resource)
path = path.strip("/")
paths = path.split("/")
actual_path = ""
i = 0
for p in paths:
i += 1
actual_path += "/" + p
try:
res = self.root[actual_path]
except KeyError:
res = None
if res is None:
resource.path = actual_path
self.root[actual_path] = resource
self._observeLayer._readers[resource.path]= {}
self._observeLayer._relations[resource.path] = {}
return True
def remove_resource(self, path):
"""
Helper function to remove resources.
:param path: the path for the unwanted resource
:rtype : the removed object
"""
path = path.strip("/")
paths = path.split("/")
actual_path = ""
i = 0
for p in paths:
i += 1
actual_path += "/" + p
try:
res = self.root[actual_path]
except KeyError:
res = None
if res is not None:
# notify all subscribers that the resource has been deleted
self.notify(res,True)
self._observeLayer._remove_relations(res)
del(self.root[actual_path])
return res
def _start_retransmission(self, transaction, message):
"""
Start the retransmission task.
:type transaction: Transaction
:param transaction: the transaction that owns the message that needs retransmission
:type message: Message
:param message: the message that needs the retransmission task
"""
with transaction:
if message.type == defines.Types['CON']:
future_time = random.uniform(defines.ACK_TIMEOUT, (defines.ACK_TIMEOUT * defines.ACK_RANDOM_FACTOR))
transaction.retransmit_thread = threading.Thread(target=self._retransmit,
args=(transaction, message, future_time, 0))
transaction.retransmit_stop = threading.Event()
self.to_be_stopped.append(transaction.retransmit_stop)
transaction.retransmit_thread.start()
def _retransmit(self, transaction, message, future_time, retransmit_count):
"""
Thread function to retransmit the message in the future
:param transaction: the transaction that owns the message that needs retransmission
:param message: the message that needs the retransmission task
:param future_time: the amount of time to wait before a new attempt
:param retransmit_count: the number of retransmissions
"""
with transaction:
while retransmit_count < defines.MAX_RETRANSMIT and (not message.acknowledged and not message.rejected) \
and not self.stopped.isSet():
if transaction.retransmit_stop is not None:
transaction.retransmit_stop.wait(timeout=future_time)
if not message.acknowledged and not message.rejected and not self.stopped.isSet():
retransmit_count += 1
future_time *= 2
self.send_datagram(message)
if message.acknowledged or message.rejected:
message.timeouted = False
else:
logger.warning("Give up on message {message}".format(message=message.line_print))
message.timeouted = True
if message.observe is not None:
self._observeLayer.remove_subscriber(message)
try:
self.to_be_stopped.remove(transaction.retransmit_stop)
except ValueError:
pass
transaction.retransmit_stop = None
transaction.retransmit_thread = None
def _start_separate_timer(self, transaction):
"""
Start a thread to handle separate mode.
:type transaction: Transaction
:param transaction: the transaction that is in processing
:rtype : the Timer object
"""
t = threading.Timer(defines.ACK_TIMEOUT, self._send_ack, (transaction,))
t.start()
return t
@staticmethod
def _stop_separate_timer(timer):
"""
Stop the separate Thread if an answer has been already provided to the client.
:param timer: The Timer object
"""
timer.cancel()
def _send_ack(self, transaction):
"""
Sends an ACK message for the request.
:param transaction: the transaction that owns the request
"""
ack = Message()
ack.type = defines.Types['ACK']
# TODO handle mutex on transaction
if not transaction.request.acknowledged and transaction.request.type == defines.Types["CON"]:
ack = self._messageLayer.send_empty(transaction, transaction.request, ack)
self.send_datagram(ack)
def notify(self, resource, delete = False):
"""
Notifies the observers of a certain resource.
:param resource: the resource
"""
observers = self._observeLayer.notify(resource)
readers = self._observeLayer.notify_read(resource)
logger.debug("Notify")
payload = resource.payload
for transaction in observers+readers:
with transaction:
transaction.response = None
transaction = self._requestLayer.receive_request(transaction)
transaction = self._observeLayer.send_response(transaction)
transaction = self._blockLayer.send_response(transaction)
transaction = self._messageLayer.send_response(transaction)
if transaction.response is not None:
notify_type = "NON" if self._qos == 0 else "CON"
transaction.response.type = defines.Types[notify_type]
transaction.response.payload = payload
if delete:
transaction.response.code = defines.Codes.NOT_FOUND.number
transaction.response.payload = "Deleted"
del transaction.response.observe
if transaction.response.type == defines.Types["CON"]:
self._start_retransmission(transaction, transaction.response)
self.send_datagram(transaction.response)
