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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:`RequestLineTooLong`
13 * :exc:`StatusLineTooLong`
14 * :exc:`HeaderLineTooLong`
15 * :exc:`TooManyHeaders`
16 * :exc:`ProxyError`
17 * :exc:`InvalidProxyMessage`
18 * :exc:`InvalidProxyStatus`
19 * :exc:`InvalidMessage`
20 * :exc:`InvalidMethod`
21 * :exc:`InvalidProtocol`
22 * :exc:`InvalidStatus`
23 * :exc:`InvalidStatusCode` (legacy)
24 * :exc:`InvalidHeader`
25 * :exc:`InvalidHeaderFormat`
26 * :exc:`InvalidHeaderValue`
27 * :exc:`InvalidOrigin`
28 * :exc:`InvalidUpgrade`
29 * :exc:`NegotiationError`
30 * :exc:`DuplicateParameter`
31 * :exc:`InvalidParameterName`
32 * :exc:`InvalidParameterValue`
33 * :exc:`AbortHandshake` (legacy)
34 * :exc:`RedirectHandshake` (legacy)
35 * :exc:`ProtocolError` (Sans-I/O)
36 * :exc:`PayloadTooBig` (Sans-I/O)
37 * :exc:`InvalidState` (Sans-I/O)
38 * :exc:`ConcurrencyError`
40"""
42from __future__ import annotations
44import warnings
46from .imports import lazy_import
49__all__ = [
50 "WebSocketException",
51 "ConnectionClosed",
52 "ConnectionClosedOK",
53 "ConnectionClosedError",
54 "InvalidURI",
55 "InvalidProxy",
56 "InvalidHandshake",
57 "SecurityError",
58 "RequestLineTooLong",
59 "StatusLineTooLong",
60 "HeaderLineTooLong",
61 "TooManyHeaders",
62 "ProxyError",
63 "InvalidProxyMessage",
64 "InvalidProxyStatus",
65 "InvalidMessage",
66 "InvalidMethod",
67 "InvalidProtocol",
68 "InvalidStatus",
69 "InvalidHeader",
70 "InvalidHeaderFormat",
71 "InvalidHeaderValue",
72 "InvalidOrigin",
73 "InvalidUpgrade",
74 "NegotiationError",
75 "DuplicateParameter",
76 "InvalidParameterName",
77 "InvalidParameterValue",
78 "ProtocolError",
79 "PayloadTooBig",
80 "InvalidState",
81 "ConcurrencyError",
82]
85class WebSocketException(Exception):
86 """
87 Base class for all exceptions defined by websockets.
89 """
92class ConnectionClosed(WebSocketException):
93 """
94 Raised when trying to interact with a closed connection.
96 Attributes:
97 rcvd: If a close frame was received, its code and reason are available
98 in ``rcvd.code`` and ``rcvd.reason``.
99 sent: If a close frame was sent, its code and reason are available
100 in ``sent.code`` and ``sent.reason``.
101 rcvd_then_sent: If close frames were received and sent, this attribute
102 tells in which order this happened, from the perspective of this
103 side of the connection.
105 """
107 def __init__(
108 self,
109 rcvd: frames.Close | None,
110 sent: frames.Close | None,
111 rcvd_then_sent: bool | None = None,
112 ) -> None:
113 self.rcvd = rcvd
114 self.sent = sent
115 self.rcvd_then_sent = rcvd_then_sent
116 assert (self.rcvd_then_sent is None) == (self.rcvd is None or self.sent is None)
118 def __str__(self) -> str:
119 if self.rcvd is None:
120 if self.sent is None:
121 return "no close frame received or sent"
122 else:
123 return f"sent {self.sent}; no close frame received"
124 else:
125 if self.sent is None:
126 return f"received {self.rcvd}; no close frame sent"
127 else:
128 if self.rcvd_then_sent:
129 return f"received {self.rcvd}; then sent {self.sent}"
130 else:
131 return f"sent {self.sent}; then received {self.rcvd}"
133 # code and reason attributes are provided for backwards-compatibility
135 @property
136 def code(self) -> int:
137 warnings.warn( # deprecated in 13.1 - 2024-09-21
138 "ConnectionClosed.code is deprecated; "
139 "use Protocol.close_code or ConnectionClosed.rcvd.code",
140 DeprecationWarning,
141 )
142 if self.rcvd is None:
143 return frames.CloseCode.ABNORMAL_CLOSURE
144 return self.rcvd.code
146 @property
147 def reason(self) -> str:
148 warnings.warn( # deprecated in 13.1 - 2024-09-21
149 "ConnectionClosed.reason is deprecated; "
150 "use Protocol.close_reason or ConnectionClosed.rcvd.reason",
151 DeprecationWarning,
152 )
153 if self.rcvd is None:
154 return ""
155 return self.rcvd.reason
158class ConnectionClosedOK(ConnectionClosed):
159 """
160 Like :exc:`ConnectionClosed`, when the connection terminated properly.
162 A close code with code 1000 (OK) or 1001 (going away) or without a code was
163 received and sent.
165 """
168class ConnectionClosedError(ConnectionClosed):
169 """
170 Like :exc:`ConnectionClosed`, when the connection terminated with an error.
172 A close frame with a code other than 1000 (OK) or 1001 (going away) was
173 received or sent, or the closing handshake didn't complete properly.
175 """
178class InvalidURI(WebSocketException):
179 """
180 Raised when connecting to a URI that isn't a valid WebSocket URI.
182 """
184 def __init__(self, uri: str, msg: str) -> None:
185 self.uri = uri
186 self.msg = msg
188 def __str__(self) -> str:
189 return f"{self.uri} isn't a valid URI: {self.msg}"
192class InvalidProxy(WebSocketException):
193 """
194 Raised when connecting via a proxy that isn't valid.
196 """
198 def __init__(self, proxy: str, msg: str) -> None:
199 self.proxy = proxy
200 self.msg = msg
202 def __str__(self) -> str:
203 return f"{self.proxy} isn't a valid proxy: {self.msg}"
206class InvalidHandshake(WebSocketException):
207 """
208 Base class for exceptions raised when the opening handshake fails.
210 """
213class SecurityError(InvalidHandshake):
214 """
215 Raised when a handshake request or response breaks a security rule.
217 Security limits can be configured with :doc:`environment variables
218 <../reference/variables>`.
220 """
223class RequestLineTooLong(SecurityError):
224 """
225 Raised when the request line of a handshake request is too long.
227 """
230class StatusLineTooLong(SecurityError):
231 """
232 Raised when the status line of a handshake response is too long.
234 """
237class HeaderLineTooLong(SecurityError):
238 """
239 Raised when a header line of a handshake request or response is too long.
241 """
244class TooManyHeaders(SecurityError):
245 """
246 Raised when a handshake request or response has too many headers.
248 """
251class ProxyError(InvalidHandshake):
252 """
253 Raised when failing to connect to a proxy.
255 """
258class InvalidProxyMessage(ProxyError):
259 """
260 Raised when an HTTP proxy response is malformed.
262 """
265class InvalidProxyStatus(ProxyError):
266 """
267 Raised when an HTTP proxy rejects the connection.
269 """
271 def __init__(self, response: http11.Response) -> None:
272 self.response = response
274 def __str__(self) -> str:
275 return f"proxy rejected connection: HTTP {self.response.status_code:d}"
278class InvalidMessage(InvalidHandshake):
279 """
280 Raised when a handshake request or response is malformed.
282 """
285class InvalidMethod(InvalidHandshake):
286 """
287 Raised when a handshake request doesn't use HTTP GET.
289 """
291 def __init__(self, method: str) -> None:
292 self.method = method
294 def __str__(self) -> str:
295 return f"unsupported HTTP method: {self.method}"
298class InvalidProtocol(InvalidHandshake):
299 """
300 Raised when a handshake request doesn't use HTTP/1.1.
302 """
304 def __init__(self, protocol: str) -> None:
305 self.protocol = protocol
307 def __str__(self) -> str:
308 return f"unsupported HTTP version: {self.protocol}"
311class InvalidStatus(InvalidHandshake):
312 """
313 Raised when a handshake response rejects the WebSocket upgrade.
315 """
317 def __init__(self, response: http11.Response) -> None:
318 self.response = response
320 def __str__(self) -> str:
321 return (
322 f"server rejected WebSocket connection: HTTP {self.response.status_code:d}"
323 )
326class InvalidHeader(InvalidHandshake):
327 """
328 Raised when an HTTP header doesn't have a valid format or value.
330 """
332 def __init__(self, name: str, value: str | None = None) -> None:
333 self.name = name
334 self.value = value
336 def __str__(self) -> str:
337 if self.value is None:
338 return f"missing {self.name} header"
339 elif self.value == "":
340 return f"empty {self.name} header"
341 else:
342 return f"invalid {self.name} header: {self.value}"
345class InvalidHeaderFormat(InvalidHeader):
346 """
347 Raised when an HTTP header cannot be parsed.
349 The format of the header doesn't match the grammar for that header.
351 """
353 def __init__(self, name: str, error: str, header: str, pos: int) -> None:
354 super().__init__(name, f"{error} at {pos} in {header}")
357class InvalidHeaderValue(InvalidHeader):
358 """
359 Raised when an HTTP header has a wrong value.
361 The format of the header is correct but the value isn't acceptable.
363 """
366class InvalidOrigin(InvalidHeader):
367 """
368 Raised when the Origin header in a request isn't allowed.
370 """
372 def __init__(self, origin: str | None) -> None:
373 super().__init__("Origin", origin)
376class InvalidUpgrade(InvalidHeader):
377 """
378 Raised when the Upgrade or Connection header isn't correct.
380 """
383class NegotiationError(InvalidHandshake):
384 """
385 Raised when negotiating an extension or a subprotocol fails.
387 """
390class DuplicateParameter(NegotiationError):
391 """
392 Raised when a parameter name is repeated in an extension header.
394 """
396 def __init__(self, name: str) -> None:
397 self.name = name
399 def __str__(self) -> str:
400 return f"duplicate parameter: {self.name}"
403class InvalidParameterName(NegotiationError):
404 """
405 Raised when a parameter name in an extension header is invalid.
407 """
409 def __init__(self, name: str) -> None:
410 self.name = name
412 def __str__(self) -> str:
413 return f"invalid parameter name: {self.name}"
416class InvalidParameterValue(NegotiationError):
417 """
418 Raised when a parameter value in an extension header is invalid.
420 """
422 def __init__(self, name: str, value: str | None) -> None:
423 self.name = name
424 self.value = value
426 def __str__(self) -> str:
427 if self.value is None:
428 return f"missing value for parameter {self.name}"
429 elif self.value == "":
430 return f"empty value for parameter {self.name}"
431 else:
432 return f"invalid value for parameter {self.name}: {self.value}"
435class ProtocolError(WebSocketException):
436 """
437 Raised when receiving or sending a frame that breaks the protocol.
439 The Sans-I/O implementation raises this exception when:
441 * receiving or sending a frame that contains invalid data;
442 * receiving or sending an invalid sequence of frames.
444 """
447class PayloadTooBig(WebSocketException):
448 """
449 Raised when parsing a frame with a payload that exceeds the maximum size.
451 The Sans-I/O layer uses this exception internally. It doesn't bubble up to
452 the I/O layer.
454 The :meth:`~websockets.extensions.Extension.decode` method of extensions
455 must raise :exc:`PayloadTooBig` if decoding a frame would exceed the limit.
457 """
459 def __init__(
460 self,
461 size_or_message: int | None | str,
462 max_size: int | None = None,
463 current_size: int | None = None,
464 ) -> None:
465 if isinstance(size_or_message, str):
466 assert max_size is None
467 assert current_size is None
468 warnings.warn( # deprecated in 14.0 - 2024-11-09
469 "PayloadTooBig(message) is deprecated; "
470 "change to PayloadTooBig(size, max_size)",
471 DeprecationWarning,
472 )
473 self.message: str | None = size_or_message
474 else:
475 self.message = None
476 self.size: int | None = size_or_message
477 assert max_size is not None
478 self.max_size: int = max_size
479 self.current_size: int | None = None
480 self.set_current_size(current_size)
482 def __str__(self) -> str:
483 if self.message is not None:
484 return self.message
485 else:
486 message = "frame "
487 if self.size is not None:
488 message += f"with {self.size} bytes "
489 if self.current_size is not None:
490 message += f"after reading {self.current_size} bytes "
491 message += f"exceeds limit of {self.max_size} bytes"
492 return message
494 def set_current_size(self, current_size: int | None) -> None:
495 assert self.current_size is None
496 if current_size is not None:
497 self.max_size += current_size
498 self.current_size = current_size
501class InvalidState(WebSocketException, AssertionError):
502 """
503 Raised when sending a frame is forbidden in the current state.
505 Specifically, the Sans-I/O layer raises this exception when:
507 * sending a data frame to a connection in a state other
508 :attr:`~websockets.protocol.State.OPEN`;
509 * sending a control frame to a connection in a state other than
510 :attr:`~websockets.protocol.State.OPEN` or
511 :attr:`~websockets.protocol.State.CLOSING`.
513 """
516class ConcurrencyError(WebSocketException, RuntimeError):
517 """
518 Raised when receiving or sending messages concurrently.
520 WebSocket is a connection-oriented protocol. Reads must be serialized; so
521 must be writes. However, reading and writing concurrently is possible.
523 """
526# At the bottom to break import cycles created by type annotations.
527from . import frames, http11 # noqa: E402
530lazy_import(
531 globals(),
532 deprecated_aliases={
533 # deprecated in 14.0 - 2024-11-09
534 "AbortHandshake": ".legacy.exceptions",
535 "InvalidStatusCode": ".legacy.exceptions",
536 "RedirectHandshake": ".legacy.exceptions",
537 "WebSocketProtocolError": ".legacy.exceptions",
538 },
539)