Source code for soco.events_base

# pylint: disable=not-context-manager

# NOTE: The pylint not-content-manager warning is disabled pending the fix of
# a bug in pylint. See https://github.com/PyCQA/pylint/issues/782


"""Base classes used by :py:mod:`soco.events` and
:py:mod:`soco.events_twisted`."""


import atexit
import logging
import socket
import time
import threading
import weakref
from queue import Queue

from . import config
from .data_structures_entry import from_didl_string
from .exceptions import SoCoException, SoCoFault, EventParseException
from .utils import camel_to_underscore
from .xml import XML

log = logging.getLogger(__name__)  # pylint: disable=C0103


# pylint: disable=too-many-branches
[docs]def parse_event_xml(xml_event): """Parse the body of a UPnP event. Args: xml_event (bytes): bytes containing the body of the event encoded with utf-8. Returns: dict: A dict with keys representing the evented variables. The relevant value will usually be a string representation of the variable's value, but may on occasion be: * a dict (eg when the volume changes, the value will itself be a dict containing the volume for each channel: :code:`{'Volume': {'LF': '100', 'RF': '100', 'Master': '36'}}`) * an instance of a `DidlObject` subclass (eg if it represents track metadata). * a `SoCoFault` (if a variable contains illegal metadata) """ result = {} tree = XML.fromstring(xml_event) # property values are just under the propertyset, which # uses this namespace properties = tree.findall("{urn:schemas-upnp-org:event-1-0}property") for prop in properties: # pylint: disable=too-many-nested-blocks for variable in prop: # Special handling for a LastChange event specially. For details on # LastChange events, see # http://upnp.org/specs/av/UPnP-av-RenderingControl-v1-Service.pdf # and http://upnp.org/specs/av/UPnP-av-AVTransport-v1-Service.pdf if variable.tag == "LastChange": last_change_tree = XML.fromstring(variable.text.encode("utf-8")) # We assume there is only one InstanceID tag. This is true for # Sonos, as far as we know. # InstanceID can be in one of two namespaces, depending on # whether we are looking at an avTransport event, a # renderingControl event, or a Queue event # (there, it is named QueueID) instance = last_change_tree.find( "{urn:schemas-upnp-org:metadata-1-0/AVT/}InstanceID" ) if instance is None: instance = last_change_tree.find( "{urn:schemas-upnp-org:metadata-1-0/RCS/}InstanceID" ) if instance is None: instance = last_change_tree.find( "{urn:schemas-sonos-com:metadata-1-0/Queue/}QueueID" ) # Look at each variable within the LastChange event for last_change_var in instance: tag = last_change_var.tag # Remove any namespaces from the tags if tag.startswith("{"): tag = tag.split("}", 1)[1] # Un-camel case it tag = camel_to_underscore(tag) # Now extract the relevant value for the variable. # The UPnP specs suggest that the value of any variable # evented via a LastChange Event will be in the 'val' # attribute, but audio related variables may also have a # 'channel' attribute. In addition, it seems that Sonos # sometimes uses a text value instead: see # http://forums.sonos.com/showthread.php?t=34663 value = last_change_var.get("val") if value is None: value = last_change_var.text # If DIDL metadata is returned, convert it to a music # library data structure if value.startswith("<DIDL-Lite"): # Wrap any parsing exception in a SoCoFault, so the # user can handle it try: value = from_didl_string(value)[0] except SoCoException as original_exception: log.warning( "Event contains illegal metadata" "for '%s'.\n" "Error message: '%s'\n" "The result will be a SoCoFault.", tag, str(original_exception), ) event_parse_exception = EventParseException( tag, value, original_exception ) value = SoCoFault(event_parse_exception) channel = last_change_var.get("channel") if channel is not None: if result.get(tag) is None: result[tag] = {} result[tag][channel] = value else: result[tag] = value else: result[camel_to_underscore(variable.tag)] = variable.text return result
[docs]class Event: """A read-only object representing a received event. The values of the evented variables can be accessed via the ``variables`` dict, or as attributes on the instance itself. You should treat all attributes as read-only. Args: sid (str): the subscription id. seq (str): the event sequence number for that subscription. timestamp (str): the time that the event was received (from Python's `time.time` function). service (str): the service which is subscribed to the event. variables (dict, optional): contains the ``{names: values}`` of the evented variables. Defaults to `None`. The values may be `SoCoFault` objects if the metadata could not be parsed. Raises: AttributeError: Not all attributes are returned with each event. An `AttributeError` will be raised if you attempt to access as an attribute a variable which was not returned in the event. Example: >>> print event.variables['transport_state'] 'STOPPED' >>> print event.transport_state 'STOPPED' """ # pylint: disable=too-few-public-methods, too-many-arguments def __init__(self, sid, seq, service, timestamp, variables=None): # Initialisation has to be done like this, because __setattr__ is # overridden, and will not allow direct setting of attributes self.__dict__["sid"] = sid self.__dict__["seq"] = seq self.__dict__["timestamp"] = timestamp self.__dict__["service"] = service self.__dict__["variables"] = variables if variables is not None else {} def __getattr__(self, name): if name in self.variables: return self.variables[name] else: raise AttributeError("No such attribute: %s" % name) def __setattr__(self, name, value): """Disable (most) attempts to set attributes. This is not completely foolproof. It just acts as a warning! See `object.__setattr__`. """ raise TypeError("Event object does not support attribute assignment")
[docs]class EventNotifyHandlerBase: """Base class for `soco.events.EventNotifyHandler` and `soco.events_twisted.EventNotifyHandler`. """ # pylint: disable=too-many-public-methods
[docs] def handle_notification(self, headers, content): """Handle a ``NOTIFY`` request by building an `Event` object and sending it to the relevant Subscription object. A ``NOTIFY`` request will be sent by a Sonos device when a state variable changes. See the `UPnP Spec ยง4.3 [pdf] <http://upnp.org/specs/arch/UPnP-arch -DeviceArchitecture-v1.1.pdf>`_ for details. Args: headers (dict): A dict of received headers. content (str): A string of received content. Note: Each of the :py:mod:`soco.events` and the :py:mod:`soco.events_twisted` modules has a **subscriptions_map** object which keeps a record of Subscription objects. The *get_subscription* method of the **subscriptions_map** object is used to look up the subscription to which the event relates. When the Event Listener runs in a thread (the default), a lock is used by this method for thread safety. The *send_event* method of the relevant Subscription will first check to see whether the *callback* variable of the Subscription has been set. If it has been and is callable, then the *callback* will be called with the `Event` object. Otherwise, the `Event` object will be sent to the event queue of the Subscription object. The *callback* variable of the Subscription object is intended for use only if :py:mod:`soco.events_twisted` is being used, as calls to it are not threadsafe. This method calls the log_event method, which must be overridden in the class that inherits from this class. """ timestamp = time.time() seq = headers["seq"] # Event sequence number sid = headers["sid"] # Event Subscription Identifier # find the relevant service from the sid # pylint: disable=no-member subscription = self.subscriptions_map.get_subscription(sid) # It might have been removed by another thread if subscription: service = subscription.service self.log_event(seq, service.service_id, timestamp) log.debug("Event content: %s", content) variables = parse_event_xml(content) # Build the Event object event = Event(sid, seq, service, timestamp, variables) # pass the event details on to the service so it can update # its cache. # pylint: disable=protected-access service._update_cache_on_event(event) # Pass the event on for handling subscription.send_event(event) else: log.info("No service registered for %s", sid)
# pylint: disable=missing-docstring def log_event(self, seq, service_id, timestamp): raise NotImplementedError
[docs]class EventListenerBase: """Base class for `soco.events.EventListener` and `soco.events_twisted.EventListener`. """ def __init__(self): #: `bool`: Indicates whether the server is currently running self.is_running = False self._start_lock = threading.Lock() #: `tuple`: The address (ip, port) on which the server is #: configured to listen. # Empty for the moment. (It is set in `start`) self.address = () #: `int`: Port on which to listen. self.requested_port_number = config.EVENT_LISTENER_PORT
[docs] def start(self, any_zone): """Start the event listener listening on the local machine. Args: any_zone (SoCo): Any Sonos device on the network. It does not matter which device. It is used only to find a local IP address reachable by the Sonos net. """ # Find our local network IP address which is accessible to the # Sonos net, see http://stackoverflow.com/q/166506 with self._start_lock: if self.is_running: return # Use configured IP address if there is one, else detect # automatically. ip_address = get_listen_ip(any_zone.ip_address) if not ip_address: log.exception("Could not start Event Listener: check network.") # Otherwise, no point trying to start server return port = self.listen(ip_address) if not port: return self.address = (ip_address, port) self.is_running = True log.debug("Event Listener started")
[docs] def stop(self): """Stop the Event Listener.""" if not self.is_running: return self.is_running = False self.stop_listening(self.address) log.info("Event Listener stopped")
# pylint: disable=missing-docstring
[docs] def listen(self, ip_address): """Start the event listener listening on the local machine. This method is called by `start`. Args: ip_address (str): The local network interface on which the server should start listening. Returns: int: The port on which the server is listening. Note: This method must be overridden in the class that inherits from this class. """ raise NotImplementedError
# pylint: disable=missing-docstring
[docs] def stop_listening(self, address): """Stop the listener. Note: This method must be overridden in the class that inherits from this class. """ raise NotImplementedError
[docs]class SubscriptionBase: """Base class for `soco.events.Subscription` and `soco.events_twisted.Subscription` """ # pylint: disable=too-many-instance-attributes def __init__(self, service, event_queue=None): """ Args: service (Service): The SoCo `Service` to which the subscription should be made. event_queue (:class:`~queue.Queue`): A queue on which received events will be put. If not specified, a queue will be created and used. """ self.service = service #: `str`: A unique ID for this subscription self.sid = None #: `int`: The amount of time in seconds until the subscription expires. self.timeout = None #: `bool`: An indication of whether the subscription is subscribed. self.is_subscribed = False #: :class:`~queue.Queue`: The queue on which events are placed. self.events = Queue() if event_queue is None else event_queue #: `int`: The period (seconds) for which the subscription is requested self.requested_timeout = None #: :py:obj:`function`: an optional function to be called if an #: exception occurs upon autorenewal. This will be called with the #: exception (or failure, when using :py:mod:`soco.events_twisted`) #: as its only parameter. This function must be threadsafe (unless #: :py:mod:`soco.events_twisted` is being used). self.auto_renew_fail = None # A flag to make sure that an unsubscribed instance is not # resubscribed self._has_been_unsubscribed = False # The time when the subscription was made self._timestamp = None
[docs] def subscribe(self, requested_timeout=None, auto_renew=False): """Subscribe to the service. If requested_timeout is provided, a subscription valid for that number of seconds will be requested, but not guaranteed. Check `timeout` on return to find out what period of validity is actually allocated. Note: SoCo will try to unsubscribe any subscriptions which are still subscribed on program termination, but it is good practice for you to clean up by making sure that you call :meth:`unsubscribe` yourself. Args: requested_timeout(int, optional): The timeout to be requested. auto_renew (bool, optional): If `True`, renew the subscription automatically shortly before timeout. Default `False`. """ # TIMEOUT is provided for in the UPnP spec, but it is not clear if # Sonos pays any attention to it. A timeout of 86400 secs always seems # to be allocated self.requested_timeout = requested_timeout if self.is_subscribed: raise SoCoException( "Cannot subscribe Subscription instance more than once. " + "Use renew instead" ) if self._has_been_unsubscribed: raise SoCoException( "Cannot resubscribe Subscription instance once unsubscribed" ) service = self.service # The Event Listener must be running, so start it if not # pylint: disable=no-member if not self.event_listener.is_running: self.event_listener.start(service.soco) # an event subscription looks like this: # SUBSCRIBE publisher path HTTP/1.1 # HOST: publisher host:publisher port # CALLBACK: <delivery URL> # NT: upnp:event # TIMEOUT: Second-requested subscription duration (optional) # pylint: disable=unbalanced-tuple-unpacking ip_address, port = self.event_listener.address if config.EVENT_ADVERTISE_IP: ip_address = config.EVENT_ADVERTISE_IP headers = { "Callback": "<http://{}:{}>".format(ip_address, port), "NT": "upnp:event", } if requested_timeout is not None: headers["TIMEOUT"] = "Second-{}".format(requested_timeout) # pylint: disable=missing-docstring def success(headers): self.sid = headers["sid"] timeout = headers["timeout"] # According to the spec, timeout can be "infinite" or "second-123" # where 123 is a number of seconds. Sonos uses "Second-123" # (with a capital letter) if timeout.lower() == "infinite": self.timeout = None else: self.timeout = int(timeout.lstrip("Second-")) self._timestamp = time.time() self.is_subscribed = True log.info( "Subscribed to %s, sid: %s", service.base_url + service.event_subscription_url, self.sid, ) # Register the subscription so it can be looked up by sid # and unsubscribed at exit self.subscriptions_map.register(self) # Set up auto_renew if not auto_renew: return # Autorenew just before expiry, say at 85% of self.timeout seconds interval = self.timeout * 85 / 100 self._auto_renew_start(interval) # Lock out EventNotifyHandler during registration. # If events_twisted is used, this lock should always be # available, since threading is not being used. This is to prevent # the EventNotifyHandler from sending a notification before the # subscription has been registered. with self.subscriptions_map.subscriptions_lock: return self._request( "SUBSCRIBE", service.base_url + service.event_subscription_url, headers, success, )
[docs] def renew(self, requested_timeout=None, is_autorenew=False): """renew(requested_timeout=None) Renew the event subscription. You should not try to renew a subscription which has been unsubscribed, or once it has expired. Args: requested_timeout (int, optional): The period for which a renewal request should be made. If None (the default), use the timeout requested on subscription. is_autorenew (bool, optional): Whether this is an autorenewal. """ # NB This code may be called from a separate thread when # subscriptions are auto-renewed. Be careful to ensure thread-safety if is_autorenew: log_msg = "Autorenewing subscription %s" else: log_msg = "Renewing subscription %s" log.info(log_msg, self.sid) if self._has_been_unsubscribed: raise SoCoException("Cannot renew subscription once unsubscribed") if not self.is_subscribed: raise SoCoException("Cannot renew subscription before subscribing") if self.time_left == 0: raise SoCoException("Cannot renew subscription after expiry") # SUBSCRIBE publisher path HTTP/1.1 # HOST: publisher host:publisher port # SID: uuid:subscription UUID # TIMEOUT: Second-requested subscription duration (optional) headers = {"SID": self.sid} if requested_timeout is None: requested_timeout = self.requested_timeout if requested_timeout is not None: headers["TIMEOUT"] = "Second-{}".format(requested_timeout) # pylint: disable=missing-docstring def success(headers): timeout = headers["timeout"] # According to the spec, timeout can be "infinite" or "second-123" # where 123 is a number of seconds. Sonos uses "Second-123" # (with a capital letter) if timeout.lower() == "infinite": self.timeout = None else: self.timeout = int(timeout.lstrip("Second-")) self._timestamp = time.time() self.is_subscribed = True log.info( "Renewed subscription to %s, sid: %s", self.service.base_url + self.service.event_subscription_url, self.sid, ) return self._request( "SUBSCRIBE", self.service.base_url + self.service.event_subscription_url, headers, success, )
[docs] def unsubscribe(self): """unsubscribe() Unsubscribe from the service's events. Once unsubscribed, a Subscription instance should not be reused """ # Trying to unsubscribe if already unsubscribed, or not yet # subscribed, fails silently if self._has_been_unsubscribed or not self.is_subscribed: return None self._cancel_subscription() # If the subscription has timed out, an attempt to # unsubscribe from it will fail silently. if self.time_left == 0: return None # Send an unsubscribe request like this: # UNSUBSCRIBE publisher path HTTP/1.1 # HOST: publisher host:publisher port # SID: uuid:subscription UUID headers = {"SID": self.sid} # pylint: disable=missing-docstring, unused-argument def success(*arg): log.info( "Unsubscribed from %s, sid: %s", self.service.base_url + self.service.event_subscription_url, self.sid, ) return self._request( "UNSUBSCRIBE", self.service.base_url + self.service.event_subscription_url, headers, success, )
[docs] def send_event(self, event): """Send an `Event` to self.callback or self.events. If self.callback is set and is callable, it will be called with the `Event` as the only parameter. Otherwise the `Event` will be sent to self.events. As self.callback is not threadsafe, it should be set only if `soco.events_twisted.Subscription` is being used. Args: event(Event): The `Event` to send to self.callback or self.events. """ if hasattr(self, "callback"): # pylint: disable=no-member callback = self.callback else: callback = None if callback and hasattr(callback, "__call__"): callback(event) else: try: self.events.put(event) # pylint: disable=broad-except except Exception as ex: log.debug("Error putting event %s, ex=%s", event, ex)
# pylint: disable=missing-docstring def _auto_renew_start(self, interval): """Starts the auto_renew thread. Note: This method must be overridden in the class that inherits from this class. """ raise NotImplementedError # pylint: disable=missing-docstring def _auto_renew_cancel(self): """Cancels the auto_renew thread. Note: This method must be overridden in the class that inherits from this class. """ raise NotImplementedError # pylint: disable=missing-docstring, too-many-arguments def _request(self, method, url, headers, success): """Send a HTTP request Args: method (str): 'SUBSCRIBE' or 'UNSUBSCRIBE'. url (str): The full endpoint to which the request is being sent. headers (dict): A dict of headers, each key and each value being of type `str`. success (function): A function to be called if the request succeeds. The function will be called with a dict of response headers as its only parameter. Note: This method must be overridden in the class that inherits from this class. """ raise NotImplementedError # pylint: disable=missing-docstring def _cancel_subscription(self, msg=None): # unregister subscription # pylint: disable=no-member self.subscriptions_map.unregister(self) # Stop the event listener, if there are no other subscriptions if self.subscriptions_map.count == 0: self.event_listener.stop() # No need to do any more if this flag has been set to True if self._has_been_unsubscribed: return self.is_subscribed = False # Set the self._has_been_unsubscribed flag now # to prevent reuse of the subscription, even if # an attempt to unsubscribe fails self._has_been_unsubscribed = True self._timestamp = None # Cancel any auto renew self._auto_renew_cancel() if msg: log.info(msg) @property def time_left(self): """ `int`: The amount of time left until the subscription expires (seconds) If the subscription is unsubscribed (or not yet subscribed), `time_left` is 0. """ if self._timestamp is None: return 0 else: time_left = self.timeout - (time.time() - self._timestamp) return time_left if time_left > 0 else 0 def __enter__(self): if not self.is_subscribed: self.subscribe() return self def __exit__(self, exc_type, exc_val, exc_tb): self.unsubscribe()
[docs]class SubscriptionsMap: """Maintains a mapping of sids to `soco.events.Subscription` instances and the thread safe lock to go with it. Registers each subscription to be unsubscribed at exit. `SubscriptionsMapTwisted` inherits from this class. """ def __init__(self): super().__init__() #: `weakref.WeakValueDictionary`: Thread safe mapping. #: Used to store a mapping of sid to subscription self.subscriptions = weakref.WeakValueDictionary() # The lock to go with it # You must only ever access the mapping in the context of this lock, # eg: # with self.subscriptions_lock: # queue = self.subscriptions[sid].events #: `threading.Lock`: for use with `subscriptions` self.subscriptions_lock = threading.Lock()
[docs] def register(self, subscription): """Register a subscription by updating local mapping of sid to subscription and registering it to be unsubscribed at exit. Args: subscription(`soco.events.Subscription`): the subscription to be registered. """ # Add the queue to the master dict of subscriptions so it can be # looked up by sid. The subscriptions_lock is not used here as # it is used in Subscription.subscribe() in the events_base # module, from which the register function is called. self.subscriptions[subscription.sid] = subscription # Register subscription to be unsubscribed at exit if still alive # This will not happen if exit is abnormal (eg in response to a # signal or fatal interpreter error - see the docs for `atexit`). atexit.register(subscription.unsubscribe)
[docs] def unregister(self, subscription): """Unregister a subscription by updating local mapping of sid to subscription instances. Args: subscription(`soco.events.Subscription`): the subscription to be unregistered. When using :py:mod:`soco.events_twisted`, an instance of `soco.events_twisted.Subscription` will be unregistered. """ with self.subscriptions_lock: try: del self.subscriptions[subscription.sid] except KeyError: pass
[docs] def get_subscription(self, sid): """Look up a subscription from a sid. Args: sid(str): The sid from which to look up the subscription. Returns: `soco.events.Subscription`: The subscription relating to that sid. When using :py:mod:`soco.events_twisted`, an instance of `soco.events_twisted.Subscription` will be returned. """ with self.subscriptions_lock: return self.subscriptions.get(sid)
@property def count(self): """ `int`: The number of active subscriptions. """ with self.subscriptions_lock: return len(self.subscriptions)
[docs]def get_listen_ip(ip_address): """Find the listen ip address.""" if config.EVENT_LISTENER_IP: return config.EVENT_LISTENER_IP sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) try: sock.connect((ip_address, config.EVENT_LISTENER_PORT)) return sock.getsockname()[0] except socket.error: return None finally: sock.close()