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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:`TooManyFragments`
38 * :exc:`InvalidState` (Sans-I/O)
39 * :exc:`ConcurrencyError`
41"""
43from __future__ import annotations
45import warnings
47from .imports import lazy_import
50__all__ = [
51 "WebSocketException",
52 "ConnectionClosed",
53 "ConnectionClosedOK",
54 "ConnectionClosedError",
55 "InvalidURI",
56 "InvalidProxy",
57 "InvalidHandshake",
58 "SecurityError",
59 "RequestLineTooLong",
60 "StatusLineTooLong",
61 "HeaderLineTooLong",
62 "TooManyHeaders",
63 "TooManyFragments",
64 "ProxyError",
65 "InvalidProxyMessage",
66 "InvalidProxyStatus",
67 "InvalidMessage",
68 "InvalidMethod",
69 "InvalidProtocol",
70 "InvalidStatus",
71 "InvalidHeader",
72 "InvalidHeaderFormat",
73 "InvalidHeaderValue",
74 "InvalidOrigin",
75 "InvalidUpgrade",
76 "NegotiationError",
77 "DuplicateParameter",
78 "InvalidParameterName",
79 "InvalidParameterValue",
80 "ProtocolError",
81 "PayloadTooBig",
82 "InvalidState",
83 "ConcurrencyError",
84]
87class WebSocketException(Exception):
88 """
89 Base class for all exceptions defined by websockets.
91 """
94class ConnectionClosed(WebSocketException):
95 """
96 Raised when trying to interact with a closed connection.
98 Attributes:
99 rcvd: If a close frame was received, its code and reason are available
100 in ``rcvd.code`` and ``rcvd.reason``.
101 sent: If a close frame was sent, its code and reason are available
102 in ``sent.code`` and ``sent.reason``.
103 rcvd_then_sent: If close frames were received and sent, this attribute
104 tells in which order this happened, from the perspective of this
105 side of the connection.
107 """
109 def __init__(
110 self,
111 rcvd: frames.Close | None,
112 sent: frames.Close | None,
113 rcvd_then_sent: bool | None = None,
114 ) -> None:
115 self.rcvd = rcvd
116 self.sent = sent
117 self.rcvd_then_sent = rcvd_then_sent
118 assert (self.rcvd_then_sent is None) == (self.rcvd is None or self.sent is None)
120 def __str__(self) -> str:
121 if self.rcvd is None:
122 if self.sent is None:
123 return "no close frame received or sent"
124 else:
125 return f"sent {self.sent}; no close frame received"
126 else:
127 if self.sent is None:
128 return f"received {self.rcvd}; no close frame sent"
129 else:
130 if self.rcvd_then_sent:
131 return f"received {self.rcvd}; then sent {self.sent}"
132 else:
133 return f"sent {self.sent}; then received {self.rcvd}"
135 # code and reason attributes are provided for backwards-compatibility
137 @property
138 def code(self) -> int:
139 warnings.warn( # deprecated in 13.1 - 2024-09-21
140 "ConnectionClosed.code is deprecated; "
141 "use Protocol.close_code or ConnectionClosed.rcvd.code",
142 DeprecationWarning,
143 )
144 if self.rcvd is None:
145 return frames.CloseCode.ABNORMAL_CLOSURE
146 return self.rcvd.code
148 @property
149 def reason(self) -> str:
150 warnings.warn( # deprecated in 13.1 - 2024-09-21
151 "ConnectionClosed.reason is deprecated; "
152 "use Protocol.close_reason or ConnectionClosed.rcvd.reason",
153 DeprecationWarning,
154 )
155 if self.rcvd is None:
156 return ""
157 return self.rcvd.reason
160class ConnectionClosedOK(ConnectionClosed):
161 """
162 Like :exc:`ConnectionClosed`, when the connection terminated properly.
164 A close code with code 1000 (OK) or 1001 (going away) or without a code was
165 received and sent.
167 """
170class ConnectionClosedError(ConnectionClosed):
171 """
172 Like :exc:`ConnectionClosed`, when the connection terminated with an error.
174 A close frame with a code other than 1000 (OK) or 1001 (going away) was
175 received or sent, or the closing handshake didn't complete properly.
177 """
180class InvalidURI(WebSocketException):
181 """
182 Raised when connecting to a URI that isn't a valid WebSocket URI.
184 """
186 def __init__(self, uri: str, msg: str) -> None:
187 self.uri = uri
188 self.msg = msg
190 def __str__(self) -> str:
191 return f"{self.uri} isn't a valid URI: {self.msg}"
194class InvalidProxy(WebSocketException):
195 """
196 Raised when connecting via a proxy that isn't valid.
198 """
200 def __init__(self, proxy: str, msg: str) -> None:
201 self.proxy = proxy
202 self.msg = msg
204 def __str__(self) -> str:
205 return f"{self.proxy} isn't a valid proxy: {self.msg}"
208class InvalidHandshake(WebSocketException):
209 """
210 Base class for exceptions raised when the opening handshake fails.
212 """
215class SecurityError(InvalidHandshake):
216 """
217 Raised when a handshake request or response breaks a security rule.
219 Security limits can be configured with :doc:`environment variables
220 <../reference/variables>`.
222 """
225class RequestLineTooLong(SecurityError):
226 """
227 Raised when the request line of a handshake request is too long.
229 """
232class StatusLineTooLong(SecurityError):
233 """
234 Raised when the status line of a handshake response is too long.
236 """
239class HeaderLineTooLong(SecurityError):
240 """
241 Raised when a header line of a handshake request or response is too long.
243 """
246class TooManyHeaders(SecurityError):
247 """
248 Raised when a handshake request or response has too many headers.
250 """
253class ProxyError(InvalidHandshake):
254 """
255 Raised when failing to connect to a proxy.
257 """
260class InvalidProxyMessage(ProxyError):
261 """
262 Raised when an HTTP proxy response is malformed.
264 """
267class InvalidProxyStatus(ProxyError):
268 """
269 Raised when an HTTP proxy rejects the connection.
271 """
273 def __init__(self, response: http11.Response) -> None:
274 self.response = response
276 def __str__(self) -> str:
277 return f"proxy rejected connection: HTTP {self.response.status_code:d}"
280class InvalidMessage(InvalidHandshake):
281 """
282 Raised when a handshake request or response is malformed.
284 """
287class InvalidMethod(InvalidHandshake):
288 """
289 Raised when a handshake request doesn't use HTTP GET.
291 """
293 def __init__(self, method: str) -> None:
294 self.method = method
296 def __str__(self) -> str:
297 return f"unsupported HTTP method: {self.method}"
300class InvalidProtocol(InvalidHandshake):
301 """
302 Raised when a handshake request doesn't use HTTP/1.1.
304 """
306 def __init__(self, protocol: str) -> None:
307 self.protocol = protocol
309 def __str__(self) -> str:
310 return f"unsupported HTTP version: {self.protocol}"
313class InvalidStatus(InvalidHandshake):
314 """
315 Raised when a handshake response rejects the WebSocket upgrade.
317 """
319 def __init__(self, response: http11.Response) -> None:
320 self.response = response
322 def __str__(self) -> str:
323 return (
324 f"server rejected WebSocket connection: HTTP {self.response.status_code:d}"
325 )
328class InvalidHeader(InvalidHandshake):
329 """
330 Raised when an HTTP header doesn't have a valid format or value.
332 """
334 def __init__(self, name: str, value: str | None = None) -> None:
335 self.name = name
336 self.value = value
338 def __str__(self) -> str:
339 if self.value is None:
340 return f"missing {self.name} header"
341 elif self.value == "":
342 return f"empty {self.name} header"
343 else:
344 return f"invalid {self.name} header: {self.value}"
347class InvalidHeaderFormat(InvalidHeader):
348 """
349 Raised when an HTTP header cannot be parsed.
351 The format of the header doesn't match the grammar for that header.
353 """
355 def __init__(self, name: str, error: str, header: str, pos: int) -> None:
356 super().__init__(name, f"{error} at {pos} in {header}")
359class InvalidHeaderValue(InvalidHeader):
360 """
361 Raised when an HTTP header has a wrong value.
363 The format of the header is correct but the value isn't acceptable.
365 """
368class InvalidOrigin(InvalidHeader):
369 """
370 Raised when the Origin header in a request isn't allowed.
372 """
374 def __init__(self, origin: str | None) -> None:
375 super().__init__("Origin", origin)
378class InvalidUpgrade(InvalidHeader):
379 """
380 Raised when the Upgrade or Connection header isn't correct.
382 """
385class NegotiationError(InvalidHandshake):
386 """
387 Raised when negotiating an extension or a subprotocol fails.
389 """
392class DuplicateParameter(NegotiationError):
393 """
394 Raised when a parameter name is repeated in an extension header.
396 """
398 def __init__(self, name: str) -> None:
399 self.name = name
401 def __str__(self) -> str:
402 return f"duplicate parameter: {self.name}"
405class InvalidParameterName(NegotiationError):
406 """
407 Raised when a parameter name in an extension header is invalid.
409 """
411 def __init__(self, name: str) -> None:
412 self.name = name
414 def __str__(self) -> str:
415 return f"invalid parameter name: {self.name}"
418class InvalidParameterValue(NegotiationError):
419 """
420 Raised when a parameter value in an extension header is invalid.
422 """
424 def __init__(self, name: str, value: str | None) -> None:
425 self.name = name
426 self.value = value
428 def __str__(self) -> str:
429 if self.value is None:
430 return f"missing value for parameter {self.name}"
431 elif self.value == "":
432 return f"empty value for parameter {self.name}"
433 else:
434 return f"invalid value for parameter {self.name}: {self.value}"
437class ProtocolError(WebSocketException):
438 """
439 Raised when receiving or sending a frame that breaks the protocol.
441 The Sans-I/O implementation raises this exception when:
443 * receiving or sending a frame that contains invalid data;
444 * receiving or sending an invalid sequence of frames.
446 """
449class PayloadTooBig(WebSocketException):
450 """
451 Raised when parsing a frame with a payload that exceeds the maximum size.
453 The Sans-I/O layer uses this exception internally. It doesn't bubble up to
454 the I/O layer.
456 The :meth:`~websockets.extensions.Extension.decode` method of extensions
457 must raise :exc:`PayloadTooBig` if decoding a frame would exceed the limit.
459 """
461 def __init__(
462 self,
463 size_or_message: int | None | str,
464 max_size: int | None = None,
465 current_size: int | None = None,
466 ) -> None:
467 if isinstance(size_or_message, str):
468 assert max_size is None
469 assert current_size is None
470 warnings.warn( # deprecated in 14.0 - 2024-11-09
471 "PayloadTooBig(message) is deprecated; "
472 "change to PayloadTooBig(size, max_size)",
473 DeprecationWarning,
474 )
475 self.message: str | None = size_or_message
476 else:
477 self.message = None
478 self.size: int | None = size_or_message
479 assert max_size is not None
480 self.max_size: int = max_size
481 self.current_size: int | None = None
482 self.set_current_size(current_size)
484 def __str__(self) -> str:
485 if self.message is not None:
486 return self.message
487 else:
488 message = "frame "
489 if self.size is not None:
490 message += f"with {self.size} bytes "
491 if self.current_size is not None:
492 message += f"after reading {self.current_size} bytes "
493 message += f"exceeds limit of {self.max_size} bytes"
494 return message
496 def set_current_size(self, current_size: int | None) -> None:
497 assert self.current_size is None
498 if current_size is not None:
499 self.max_size += current_size
500 self.current_size = current_size
503class TooManyFragments(WebSocketException):
504 """Raised when reassembling message that contains too many frames."""
506 def __init__(self, max_fragments: int) -> None:
507 super().__init__(f"fragmented message exceeds limit of {max_fragments} frames")
510class InvalidState(WebSocketException, AssertionError):
511 """
512 Raised when sending a frame is forbidden in the current state.
514 Specifically, the Sans-I/O layer raises this exception when:
516 * sending a data frame to a connection in a state other
517 :attr:`~websockets.protocol.State.OPEN`;
518 * sending a control frame to a connection in a state other than
519 :attr:`~websockets.protocol.State.OPEN` or
520 :attr:`~websockets.protocol.State.CLOSING`.
522 """
525class ConcurrencyError(WebSocketException, RuntimeError):
526 """
527 Raised when receiving or sending messages concurrently.
529 WebSocket is a connection-oriented protocol. Reads must be serialized; so
530 must be writes. However, reading and writing concurrently is possible.
532 """
535# At the bottom to break import cycles created by type annotations.
536from . import frames, http11 # noqa: E402
539lazy_import(
540 globals(),
541 deprecated_aliases={
542 # deprecated in 14.0 - 2024-11-09
543 "AbortHandshake": ".legacy.exceptions",
544 "InvalidStatusCode": ".legacy.exceptions",
545 "RedirectHandshake": ".legacy.exceptions",
546 "WebSocketProtocolError": ".legacy.exceptions",
547 },
548)