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1"""
2:mod:`websockets.exceptions` defines the following hierarchy of exceptions.
4* :exc:`WebSocketException`
5 * :exc:`ConnectionClosed`
6 * :exc:`ConnectionClosedOK`
7 * :exc:`ConnectionClosedError`
8 * :exc:`InvalidURI`
9 * :exc:`InvalidProxy`
10 * :exc:`InvalidHandshake`
11 * :exc:`SecurityError`
12 * :exc:`ProxyError`
13 * :exc:`InvalidProxyMessage`
14 * :exc:`InvalidProxyStatus`
15 * :exc:`InvalidMessage`
16 * :exc:`InvalidStatus`
17 * :exc:`InvalidStatusCode` (legacy)
18 * :exc:`InvalidHeader`
19 * :exc:`InvalidHeaderFormat`
20 * :exc:`InvalidHeaderValue`
21 * :exc:`InvalidOrigin`
22 * :exc:`InvalidUpgrade`
23 * :exc:`NegotiationError`
24 * :exc:`DuplicateParameter`
25 * :exc:`InvalidParameterName`
26 * :exc:`InvalidParameterValue`
27 * :exc:`AbortHandshake` (legacy)
28 * :exc:`RedirectHandshake` (legacy)
29 * :exc:`ProtocolError` (Sans-I/O)
30 * :exc:`PayloadTooBig` (Sans-I/O)
31 * :exc:`InvalidState` (Sans-I/O)
32 * :exc:`ConcurrencyError`
34"""
36from __future__ import annotations
38import warnings
40from .imports import lazy_import
43__all__ = [
44 "WebSocketException",
45 "ConnectionClosed",
46 "ConnectionClosedOK",
47 "ConnectionClosedError",
48 "InvalidURI",
49 "InvalidProxy",
50 "InvalidHandshake",
51 "SecurityError",
52 "ProxyError",
53 "InvalidProxyMessage",
54 "InvalidProxyStatus",
55 "InvalidMessage",
56 "InvalidStatus",
57 "InvalidHeader",
58 "InvalidHeaderFormat",
59 "InvalidHeaderValue",
60 "InvalidOrigin",
61 "InvalidUpgrade",
62 "NegotiationError",
63 "DuplicateParameter",
64 "InvalidParameterName",
65 "InvalidParameterValue",
66 "ProtocolError",
67 "PayloadTooBig",
68 "InvalidState",
69 "ConcurrencyError",
70]
73class WebSocketException(Exception):
74 """
75 Base class for all exceptions defined by websockets.
77 """
80class ConnectionClosed(WebSocketException):
81 """
82 Raised when trying to interact with a closed connection.
84 Attributes:
85 rcvd: If a close frame was received, its code and reason are available
86 in ``rcvd.code`` and ``rcvd.reason``.
87 sent: If a close frame was sent, its code and reason are available
88 in ``sent.code`` and ``sent.reason``.
89 rcvd_then_sent: If close frames were received and sent, this attribute
90 tells in which order this happened, from the perspective of this
91 side of the connection.
93 """
95 def __init__(
96 self,
97 rcvd: frames.Close | None,
98 sent: frames.Close | None,
99 rcvd_then_sent: bool | None = None,
100 ) -> None:
101 self.rcvd = rcvd
102 self.sent = sent
103 self.rcvd_then_sent = rcvd_then_sent
104 assert (self.rcvd_then_sent is None) == (self.rcvd is None or self.sent is None)
106 def __str__(self) -> str:
107 if self.rcvd is None:
108 if self.sent is None:
109 return "no close frame received or sent"
110 else:
111 return f"sent {self.sent}; no close frame received"
112 else:
113 if self.sent is None:
114 return f"received {self.rcvd}; no close frame sent"
115 else:
116 if self.rcvd_then_sent:
117 return f"received {self.rcvd}; then sent {self.sent}"
118 else:
119 return f"sent {self.sent}; then received {self.rcvd}"
121 # code and reason attributes are provided for backwards-compatibility
123 @property
124 def code(self) -> int:
125 warnings.warn( # deprecated in 13.1 - 2024-09-21
126 "ConnectionClosed.code is deprecated; "
127 "use Protocol.close_code or ConnectionClosed.rcvd.code",
128 DeprecationWarning,
129 )
130 if self.rcvd is None:
131 return frames.CloseCode.ABNORMAL_CLOSURE
132 return self.rcvd.code
134 @property
135 def reason(self) -> str:
136 warnings.warn( # deprecated in 13.1 - 2024-09-21
137 "ConnectionClosed.reason is deprecated; "
138 "use Protocol.close_reason or ConnectionClosed.rcvd.reason",
139 DeprecationWarning,
140 )
141 if self.rcvd is None:
142 return ""
143 return self.rcvd.reason
146class ConnectionClosedOK(ConnectionClosed):
147 """
148 Like :exc:`ConnectionClosed`, when the connection terminated properly.
150 A close code with code 1000 (OK) or 1001 (going away) or without a code was
151 received and sent.
153 """
156class ConnectionClosedError(ConnectionClosed):
157 """
158 Like :exc:`ConnectionClosed`, when the connection terminated with an error.
160 A close frame with a code other than 1000 (OK) or 1001 (going away) was
161 received or sent, or the closing handshake didn't complete properly.
163 """
166class InvalidURI(WebSocketException):
167 """
168 Raised when connecting to a URI that isn't a valid WebSocket URI.
170 """
172 def __init__(self, uri: str, msg: str) -> None:
173 self.uri = uri
174 self.msg = msg
176 def __str__(self) -> str:
177 return f"{self.uri} isn't a valid URI: {self.msg}"
180class InvalidProxy(WebSocketException):
181 """
182 Raised when connecting via a proxy that isn't valid.
184 """
186 def __init__(self, proxy: str, msg: str) -> None:
187 self.proxy = proxy
188 self.msg = msg
190 def __str__(self) -> str:
191 return f"{self.proxy} isn't a valid proxy: {self.msg}"
194class InvalidHandshake(WebSocketException):
195 """
196 Base class for exceptions raised when the opening handshake fails.
198 """
201class SecurityError(InvalidHandshake):
202 """
203 Raised when a handshake request or response breaks a security rule.
205 Security limits can be configured with :doc:`environment variables
206 <../reference/variables>`.
208 """
211class ProxyError(InvalidHandshake):
212 """
213 Raised when failing to connect to a proxy.
215 """
218class InvalidProxyMessage(ProxyError):
219 """
220 Raised when an HTTP proxy response is malformed.
222 """
225class InvalidProxyStatus(ProxyError):
226 """
227 Raised when an HTTP proxy rejects the connection.
229 """
231 def __init__(self, response: http11.Response) -> None:
232 self.response = response
234 def __str__(self) -> str:
235 return f"proxy rejected connection: HTTP {self.response.status_code:d}"
238class InvalidMessage(InvalidHandshake):
239 """
240 Raised when a handshake request or response is malformed.
242 """
245class InvalidStatus(InvalidHandshake):
246 """
247 Raised when a handshake response rejects the WebSocket upgrade.
249 """
251 def __init__(self, response: http11.Response) -> None:
252 self.response = response
254 def __str__(self) -> str:
255 return (
256 f"server rejected WebSocket connection: HTTP {self.response.status_code:d}"
257 )
260class InvalidHeader(InvalidHandshake):
261 """
262 Raised when an HTTP header doesn't have a valid format or value.
264 """
266 def __init__(self, name: str, value: str | None = None) -> None:
267 self.name = name
268 self.value = value
270 def __str__(self) -> str:
271 if self.value is None:
272 return f"missing {self.name} header"
273 elif self.value == "":
274 return f"empty {self.name} header"
275 else:
276 return f"invalid {self.name} header: {self.value}"
279class InvalidHeaderFormat(InvalidHeader):
280 """
281 Raised when an HTTP header cannot be parsed.
283 The format of the header doesn't match the grammar for that header.
285 """
287 def __init__(self, name: str, error: str, header: str, pos: int) -> None:
288 super().__init__(name, f"{error} at {pos} in {header}")
291class InvalidHeaderValue(InvalidHeader):
292 """
293 Raised when an HTTP header has a wrong value.
295 The format of the header is correct but the value isn't acceptable.
297 """
300class InvalidOrigin(InvalidHeader):
301 """
302 Raised when the Origin header in a request isn't allowed.
304 """
306 def __init__(self, origin: str | None) -> None:
307 super().__init__("Origin", origin)
310class InvalidUpgrade(InvalidHeader):
311 """
312 Raised when the Upgrade or Connection header isn't correct.
314 """
317class NegotiationError(InvalidHandshake):
318 """
319 Raised when negotiating an extension or a subprotocol fails.
321 """
324class DuplicateParameter(NegotiationError):
325 """
326 Raised when a parameter name is repeated in an extension header.
328 """
330 def __init__(self, name: str) -> None:
331 self.name = name
333 def __str__(self) -> str:
334 return f"duplicate parameter: {self.name}"
337class InvalidParameterName(NegotiationError):
338 """
339 Raised when a parameter name in an extension header is invalid.
341 """
343 def __init__(self, name: str) -> None:
344 self.name = name
346 def __str__(self) -> str:
347 return f"invalid parameter name: {self.name}"
350class InvalidParameterValue(NegotiationError):
351 """
352 Raised when a parameter value in an extension header is invalid.
354 """
356 def __init__(self, name: str, value: str | None) -> None:
357 self.name = name
358 self.value = value
360 def __str__(self) -> str:
361 if self.value is None:
362 return f"missing value for parameter {self.name}"
363 elif self.value == "":
364 return f"empty value for parameter {self.name}"
365 else:
366 return f"invalid value for parameter {self.name}: {self.value}"
369class ProtocolError(WebSocketException):
370 """
371 Raised when receiving or sending a frame that breaks the protocol.
373 The Sans-I/O implementation raises this exception when:
375 * receiving or sending a frame that contains invalid data;
376 * receiving or sending an invalid sequence of frames.
378 """
381class PayloadTooBig(WebSocketException):
382 """
383 Raised when parsing a frame with a payload that exceeds the maximum size.
385 The Sans-I/O layer uses this exception internally. It doesn't bubble up to
386 the I/O layer.
388 The :meth:`~websockets.extensions.Extension.decode` method of extensions
389 must raise :exc:`PayloadTooBig` if decoding a frame would exceed the limit.
391 """
393 def __init__(
394 self,
395 size_or_message: int | None | str,
396 max_size: int | None = None,
397 current_size: int | None = None,
398 ) -> None:
399 if isinstance(size_or_message, str):
400 assert max_size is None
401 assert current_size is None
402 warnings.warn( # deprecated in 14.0 - 2024-11-09
403 "PayloadTooBig(message) is deprecated; "
404 "change to PayloadTooBig(size, max_size)",
405 DeprecationWarning,
406 )
407 self.message: str | None = size_or_message
408 else:
409 self.message = None
410 self.size: int | None = size_or_message
411 assert max_size is not None
412 self.max_size: int = max_size
413 self.current_size: int | None = None
414 self.set_current_size(current_size)
416 def __str__(self) -> str:
417 if self.message is not None:
418 return self.message
419 else:
420 message = "frame "
421 if self.size is not None:
422 message += f"with {self.size} bytes "
423 if self.current_size is not None:
424 message += f"after reading {self.current_size} bytes "
425 message += f"exceeds limit of {self.max_size} bytes"
426 return message
428 def set_current_size(self, current_size: int | None) -> None:
429 assert self.current_size is None
430 if current_size is not None:
431 self.max_size += current_size
432 self.current_size = current_size
435class InvalidState(WebSocketException, AssertionError):
436 """
437 Raised when sending a frame is forbidden in the current state.
439 Specifically, the Sans-I/O layer raises this exception when:
441 * sending a data frame to a connection in a state other
442 :attr:`~websockets.protocol.State.OPEN`;
443 * sending a control frame to a connection in a state other than
444 :attr:`~websockets.protocol.State.OPEN` or
445 :attr:`~websockets.protocol.State.CLOSING`.
447 """
450class ConcurrencyError(WebSocketException, RuntimeError):
451 """
452 Raised when receiving or sending messages concurrently.
454 WebSocket is a connection-oriented protocol. Reads must be serialized; so
455 must be writes. However, reading and writing concurrently is possible.
457 """
460# At the bottom to break import cycles created by type annotations.
461from . import frames, http11 # noqa: E402
464lazy_import(
465 globals(),
466 deprecated_aliases={
467 # deprecated in 14.0 - 2024-11-09
468 "AbortHandshake": ".legacy.exceptions",
469 "InvalidStatusCode": ".legacy.exceptions",
470 "RedirectHandshake": ".legacy.exceptions",
471 "WebSocketProtocolError": ".legacy.exceptions",
472 },
473)