Coverage for aiocoap/tokenmanager.py: 88%
116 statements
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1# SPDX-FileCopyrightText: Christian Amsüss and the aiocoap contributors
2#
3# SPDX-License-Identifier: MIT
5import functools
6import random
8from . import error
9from . import interfaces
11from .pipe import Pipe
14class TokenManager(interfaces.RequestInterface, interfaces.TokenManager):
15 def __init__(self, context):
16 self.context = context
18 self._token = random.randint(0, 65535)
19 self.outgoing_requests = {}
20 """Unfinished outgoing requests (identified by token and remote)"""
21 self.incoming_requests = {}
22 """Unfinished incoming requests.
24 ``(token, remote): (Pipe, stopper)`` where stopper is a
25 function unregistes the Pipe event handler and thus
26 indicates to the server the discontinued interest"""
28 self.log = self.context.log
29 self.loop = self.context.loop
31 # self.token_interface = … -- needs to be set post-construction, because the token_interface in its constructor already needs to get its manager
33 def __repr__(self):
34 return "<%s for %s>" % (
35 type(self).__name__,
36 getattr(self, "token_interface", "(unbound)"),
37 )
39 @property
40 def client_credentials(self):
41 return self.context.client_credentials
43 async def shutdown(self):
44 while self.incoming_requests:
45 key = next(iter(self.incoming_requests.keys()))
46 (_, stop) = self.incoming_requests.pop(key)
47 # This cancels them, not sending anything.
48 #
49 # FIXME should we? (RST? 5.00 Server Shutdown? An RST would only
50 # work if we pushed this further down the shutdown chain; a 5.00 we
51 # could raise in the task.)
52 stop()
53 self.incoming_requests = None
55 while self.outgoing_requests:
56 key = next(iter(self.outgoing_requests.keys()))
57 request = self.outgoing_requests.pop(key)
58 request.add_exception(error.LibraryShutdown())
59 self.outgoing_requests = None
61 await self.token_interface.shutdown()
63 def next_token(self):
64 """Reserve and return a new Token for request."""
65 # TODO: add proper Token handling
66 self._token = (self._token + 1) % (2**64)
67 return self._token.to_bytes(8, "big").lstrip(b"\0")
69 #
70 # implement the tokenmanager interface
71 #
73 def dispatch_error(self, exception, remote):
74 if self.outgoing_requests is None:
75 # Not entirely sure where it is so far; better just raise a warning
76 # than an exception later, nothing terminally bad should come of
77 # this error.
78 self.log.warning(
79 "Internal shutdown sequence msismatch: error dispatched through tokenmanager after shutdown"
80 )
81 return
83 # NetworkError is what we promise users to raise from request etc; if
84 # it's already a NetworkError and possibly more descriptive (eg. a
85 # TimeoutError), we'll just let it through (and thus allow
86 # differentiated handling eg. in application-level retries).
87 if not isinstance(exception, error.NetworkError):
88 cause = exception
89 exception = error.NetworkError(str(exception))
90 exception.__cause__ = cause
92 # The stopping calls would pop items from the pending requests --
93 # iterating once, extracting the stoppers and then calling them en
94 # batch
95 stoppers = []
96 for key, request in self.outgoing_requests.items():
97 (token, request_remote) = key
98 if request_remote == remote:
99 stoppers.append(
100 lambda request=request, exception=exception: request.add_exception(
101 exception
102 )
103 )
105 for (_, _r), (_, stopper) in self.incoming_requests.items():
106 if remote == _r:
107 stoppers.append(stopper)
108 for stopper in stoppers:
109 stopper()
111 def process_request(self, request):
112 key = (request.token, request.remote)
114 if key in self.incoming_requests:
115 # This is either a "I consider that token invalid, probably forgot
116 # about it, but here's a new request" or renewed interest in an
117 # observation, which gets modelled as a new request at thislevel
118 self.log.debug("Incoming request overrides existing request")
119 # Popping: FIXME Decide if one of them is sufficient (see `del self.incoming_requests[key]` below)
120 (pipe, stop) = self.incoming_requests.pop(key)
121 stop()
123 pipe = Pipe(request, self.log)
125 # FIXME: what can we pass down to the token_interface? certainly not
126 # the request, but maybe the request with a response filter applied?
127 def on_event(ev):
128 if ev.message is not None:
129 m = ev.message
130 # FIXME: should this code warn if token or remote are set?
131 m.token = request.token
132 m.remote = request.remote.as_response_address()
134 # The token interface may use information from that, eg.
135 # whether the request was sent reliably or not.
136 m.request = request
138 self.token_interface.send_message(
139 m,
140 # No more interest from *that* remote; as it's the only
141 # thing keeping the PR alive, it'll go its course of
142 # vanishing for lack of interest (as it would if
143 # stop were called from its other possible caller,
144 # the start of process_request when a new request comes
145 # in on the same token)
146 stop,
147 )
148 else:
149 # It'd be tempting to raise here, but typically being called
150 # from a task, it wouldn't propagate any further either, and at
151 # least here we have a logger.
152 self.log.error(
153 "Requests shouldn't receive errors at the level of a TokenManager any more, but this did: %s",
154 ev,
155 )
156 if not ev.is_last:
157 return True
159 def on_end():
160 if key in self.incoming_requests:
161 # It may not be, especially if it was popped in `(pipe, stop) = self.incoming_requests.pop(keyu)` above
162 # FIXME Decide if one of them is sufficient
163 del self.incoming_requests[key]
164 # no further cleanup to do here: any piggybackable ack was already flushed
165 # out by the first response, and if there was not even a
166 # NoResponse, something went wrong above (and we can't tell easily
167 # here).
169 stop = pipe.on_event(on_event)
170 pipe.on_interest_end(on_end)
172 self.incoming_requests[key] = (pipe, stop)
174 self.context.render_to_pipe(pipe)
176 def process_response(self, response):
177 key = (response.token, response.remote)
178 if key not in self.outgoing_requests:
179 # maybe it was a multicast...
180 key = (response.token, None)
182 try:
183 request = self.outgoing_requests[key]
184 except KeyError:
185 self.log.info("Response %r could not be matched to any request", response)
186 return False
187 else:
188 self.log.debug("Response %r matched to request %r", response, request)
190 # FIXME: there's a multicast aspect to that as well
191 #
192 # Is it necessary to look into .opt.observe here, wouldn't that better
193 # be done by the higher-level code that knows about CoAP options?
194 # Maybe, but at some point in TokenManager we *have* to look into the
195 # options to see whether to expect a short- or long-running token.
196 # Still, it would be an option not to send an is_last here and *always*
197 # have the higher-level code indicate loss of interest in that exchange
198 # when it detects that no more observations will follow.
199 final = not (
200 request.request.opt.observe == 0 and response.opt.observe is not None
201 )
203 if final:
204 self.outgoing_requests.pop(key)
206 request.add_response(response, is_last=final)
207 return True
209 #
210 # implement RequestInterface
211 #
213 async def fill_or_recognize_remote(self, message):
214 return await self.token_interface.fill_or_recognize_remote(message)
216 def request(self, request):
217 if self.outgoing_requests is None:
218 request.add_exception(error.LibraryShutdown())
219 return
221 msg = request.request
223 assert msg.code.is_request(), "Message code is not valid for request"
225 # This might easily change, but right now, relying on the Context to
226 # fill_remote early makes steps easier here.
227 assert msg.remote is not None, "Remote not pre-populated"
229 # FIXME: pick a suitably short one where available, and a longer one
230 # for observations if many short ones are already in-flight
231 msg.token = self.next_token()
233 self.log.debug(
234 "Sending request - Token: %s, Remote: %s", msg.token.hex(), msg.remote
235 )
237 # A request sent over the multicast interface will only return a single
238 # response and otherwise behave quite like an anycast request (which is
239 # probably intended).
240 if msg.remote.is_multicast:
241 self.log.warning("Sending request to multicast via unicast request method")
242 key = (msg.token, None)
243 else:
244 key = (msg.token, msg.remote)
246 self.outgoing_requests[key] = request
247 request.on_interest_end(
248 functools.partial(self.outgoing_requests.pop, key, None)
249 )
251 try:
252 send_canceller = self.token_interface.send_message(
253 msg, lambda: request.add_exception(error.MessageError)
254 )
255 except Exception as e:
256 request.add_exception(e)
257 return
259 if send_canceller is not None:
260 # This needs to be called both when the requester cancels the
261 # request, and when a response to the CON request comes in via a
262 # different CON when the original ACK was lost, so the retransmits
263 # can stop.
264 #
265 # FIXME: This might need a little sharper conditions: A fresh CON
266 # should be sufficient to stop retransmits of a CON in a first
267 # request, but when refreshing an observation, only an ACK tells us
268 # that the updated observation got through. Also, multicast needs
269 # to be an exception, but that generally needs handling here.
270 #
271 # It may be that it'd be wise to reduce the use of send_canceller
272 # to situations when the request is actualy cancelled, and pass
273 # some information to the token_interface about whether it should
274 # keep an eye out for responses on that token and cancel
275 # transmission accordingly.
276 request.on_event(lambda ev: (send_canceller(), False)[1], is_interest=False)