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"""
:mod:`websockets.exceptions` defines the following hierarchy of exceptions.
* :exc:`WebSocketException`
* :exc:`ConnectionClosed`
* :exc:`ConnectionClosedOK`
* :exc:`ConnectionClosedError`
* :exc:`InvalidURI`
* :exc:`InvalidProxy`
* :exc:`InvalidHandshake`
* :exc:`SecurityError`
* :exc:`ProxyError`
* :exc:`InvalidProxyMessage`
* :exc:`InvalidProxyStatus`
* :exc:`InvalidMessage`
* :exc:`InvalidStatus`
* :exc:`InvalidStatusCode` (legacy)
* :exc:`InvalidHeader`
* :exc:`InvalidHeaderFormat`
* :exc:`InvalidHeaderValue`
* :exc:`InvalidOrigin`
* :exc:`InvalidUpgrade`
* :exc:`NegotiationError`
* :exc:`DuplicateParameter`
* :exc:`InvalidParameterName`
* :exc:`InvalidParameterValue`
* :exc:`AbortHandshake` (legacy)
* :exc:`RedirectHandshake` (legacy)
* :exc:`ProtocolError` (Sans-I/O)
* :exc:`PayloadTooBig` (Sans-I/O)
* :exc:`InvalidState` (Sans-I/O)
* :exc:`ConcurrencyError`
"""
from __future__ import annotations
import warnings
from .imports import lazy_import
__all__ = [
"WebSocketException",
"ConnectionClosed",
"ConnectionClosedOK",
"ConnectionClosedError",
"InvalidURI",
"InvalidProxy",
"InvalidHandshake",
"SecurityError",
"ProxyError",
"InvalidProxyMessage",
"InvalidProxyStatus",
"InvalidMessage",
"InvalidStatus",
"InvalidHeader",
"InvalidHeaderFormat",
"InvalidHeaderValue",
"InvalidOrigin",
"InvalidUpgrade",
"NegotiationError",
"DuplicateParameter",
"InvalidParameterName",
"InvalidParameterValue",
"ProtocolError",
"PayloadTooBig",
"InvalidState",
"ConcurrencyError",
]
class WebSocketException(Exception):
"""
Base class for all exceptions defined by websockets.
"""
class ConnectionClosed(WebSocketException):
"""
Raised when trying to interact with a closed connection.
Attributes:
rcvd: If a close frame was received, its code and reason are available
in ``rcvd.code`` and ``rcvd.reason``.
sent: If a close frame was sent, its code and reason are available
in ``sent.code`` and ``sent.reason``.
rcvd_then_sent: If close frames were received and sent, this attribute
tells in which order this happened, from the perspective of this
side of the connection.
"""
def __init__(
self,
rcvd: frames.Close | None,
sent: frames.Close | None,
rcvd_then_sent: bool | None = None,
) -> None:
self.rcvd = rcvd
self.sent = sent
self.rcvd_then_sent = rcvd_then_sent
assert (self.rcvd_then_sent is None) == (self.rcvd is None or self.sent is None)
def __str__(self) -> str:
if self.rcvd is None:
if self.sent is None:
return "no close frame received or sent"
else:
return f"sent {self.sent}; no close frame received"
else:
if self.sent is None:
return f"received {self.rcvd}; no close frame sent"
else:
if self.rcvd_then_sent:
return f"received {self.rcvd}; then sent {self.sent}"
else:
return f"sent {self.sent}; then received {self.rcvd}"
# code and reason attributes are provided for backwards-compatibility
@property
def code(self) -> int:
warnings.warn( # deprecated in 13.1 - 2024-09-21
"ConnectionClosed.code is deprecated; "
"use Protocol.close_code or ConnectionClosed.rcvd.code",
DeprecationWarning,
)
if self.rcvd is None:
return frames.CloseCode.ABNORMAL_CLOSURE
return self.rcvd.code
@property
def reason(self) -> str:
warnings.warn( # deprecated in 13.1 - 2024-09-21
"ConnectionClosed.reason is deprecated; "
"use Protocol.close_reason or ConnectionClosed.rcvd.reason",
DeprecationWarning,
)
if self.rcvd is None:
return ""
return self.rcvd.reason
class ConnectionClosedOK(ConnectionClosed):
"""
Like :exc:`ConnectionClosed`, when the connection terminated properly.
A close code with code 1000 (OK) or 1001 (going away) or without a code was
received and sent.
"""
class ConnectionClosedError(ConnectionClosed):
"""
Like :exc:`ConnectionClosed`, when the connection terminated with an error.
A close frame with a code other than 1000 (OK) or 1001 (going away) was
received or sent, or the closing handshake didn't complete properly.
"""
class InvalidURI(WebSocketException):
"""
Raised when connecting to a URI that isn't a valid WebSocket URI.
"""
def __init__(self, uri: str, msg: str) -> None:
self.uri = uri
self.msg = msg
def __str__(self) -> str:
return f"{self.uri} isn't a valid URI: {self.msg}"
class InvalidProxy(WebSocketException):
"""
Raised when connecting via a proxy that isn't valid.
"""
def __init__(self, proxy: str, msg: str) -> None:
self.proxy = proxy
self.msg = msg
def __str__(self) -> str:
return f"{self.proxy} isn't a valid proxy: {self.msg}"
class InvalidHandshake(WebSocketException):
"""
Base class for exceptions raised when the opening handshake fails.
"""
class SecurityError(InvalidHandshake):
"""
Raised when a handshake request or response breaks a security rule.
Security limits can be configured with :doc:`environment variables
<../reference/variables>`.
"""
class ProxyError(InvalidHandshake):
"""
Raised when failing to connect to a proxy.
"""
class InvalidProxyMessage(ProxyError):
"""
Raised when an HTTP proxy response is malformed.
"""
class InvalidProxyStatus(ProxyError):
"""
Raised when an HTTP proxy rejects the connection.
"""
def __init__(self, response: http11.Response) -> None:
self.response = response
def __str__(self) -> str:
return f"proxy rejected connection: HTTP {self.response.status_code:d}"
class InvalidMessage(InvalidHandshake):
"""
Raised when a handshake request or response is malformed.
"""
class InvalidStatus(InvalidHandshake):
"""
Raised when a handshake response rejects the WebSocket upgrade.
"""
def __init__(self, response: http11.Response) -> None:
self.response = response
def __str__(self) -> str:
return (
f"server rejected WebSocket connection: HTTP {self.response.status_code:d}"
)
class InvalidHeader(InvalidHandshake):
"""
Raised when an HTTP header doesn't have a valid format or value.
"""
def __init__(self, name: str, value: str | None = None) -> None:
self.name = name
self.value = value
def __str__(self) -> str:
if self.value is None:
return f"missing {self.name} header"
elif self.value == "":
return f"empty {self.name} header"
else:
return f"invalid {self.name} header: {self.value}"
class InvalidHeaderFormat(InvalidHeader):
"""
Raised when an HTTP header cannot be parsed.
The format of the header doesn't match the grammar for that header.
"""
def __init__(self, name: str, error: str, header: str, pos: int) -> None:
super().__init__(name, f"{error} at {pos} in {header}")
class InvalidHeaderValue(InvalidHeader):
"""
Raised when an HTTP header has a wrong value.
The format of the header is correct but the value isn't acceptable.
"""
class InvalidOrigin(InvalidHeader):
"""
Raised when the Origin header in a request isn't allowed.
"""
def __init__(self, origin: str | None) -> None:
super().__init__("Origin", origin)
class InvalidUpgrade(InvalidHeader):
"""
Raised when the Upgrade or Connection header isn't correct.
"""
class NegotiationError(InvalidHandshake):
"""
Raised when negotiating an extension or a subprotocol fails.
"""
class DuplicateParameter(NegotiationError):
"""
Raised when a parameter name is repeated in an extension header.
"""
def __init__(self, name: str) -> None:
self.name = name
def __str__(self) -> str:
return f"duplicate parameter: {self.name}"
class InvalidParameterName(NegotiationError):
"""
Raised when a parameter name in an extension header is invalid.
"""
def __init__(self, name: str) -> None:
self.name = name
def __str__(self) -> str:
return f"invalid parameter name: {self.name}"
class InvalidParameterValue(NegotiationError):
"""
Raised when a parameter value in an extension header is invalid.
"""
def __init__(self, name: str, value: str | None) -> None:
self.name = name
self.value = value
def __str__(self) -> str:
if self.value is None:
return f"missing value for parameter {self.name}"
elif self.value == "":
return f"empty value for parameter {self.name}"
else:
return f"invalid value for parameter {self.name}: {self.value}"
class ProtocolError(WebSocketException):
"""
Raised when receiving or sending a frame that breaks the protocol.
The Sans-I/O implementation raises this exception when:
* receiving or sending a frame that contains invalid data;
* receiving or sending an invalid sequence of frames.
"""
class PayloadTooBig(WebSocketException):
"""
Raised when parsing a frame with a payload that exceeds the maximum size.
The Sans-I/O layer uses this exception internally. It doesn't bubble up to
the I/O layer.
The :meth:`~websockets.extensions.Extension.decode` method of extensions
must raise :exc:`PayloadTooBig` if decoding a frame would exceed the limit.
"""
def __init__(
self,
size_or_message: int | None | str,
max_size: int | None = None,
cur_size: int | None = None,
) -> None:
if isinstance(size_or_message, str):
assert max_size is None
assert cur_size is None
warnings.warn( # deprecated in 14.0 - 2024-11-09
"PayloadTooBig(message) is deprecated; "
"change to PayloadTooBig(size, max_size)",
DeprecationWarning,
)
self.message: str | None = size_or_message
else:
self.message = None
self.size: int | None = size_or_message
assert max_size is not None
self.max_size: int = max_size
self.cur_size: int | None = None
self.set_current_size(cur_size)
def __str__(self) -> str:
if self.message is not None:
return self.message
else:
message = "frame "
if self.size is not None:
message += f"with {self.size} bytes "
if self.cur_size is not None:
message += f"after reading {self.cur_size} bytes "
message += f"exceeds limit of {self.max_size} bytes"
return message
def set_current_size(self, cur_size: int | None) -> None:
assert self.cur_size is None
if cur_size is not None:
self.max_size += cur_size
self.cur_size = cur_size
class InvalidState(WebSocketException, AssertionError):
"""
Raised when sending a frame is forbidden in the current state.
Specifically, the Sans-I/O layer raises this exception when:
* sending a data frame to a connection in a state other
:attr:`~websockets.protocol.State.OPEN`;
* sending a control frame to a connection in a state other than
:attr:`~websockets.protocol.State.OPEN` or
:attr:`~websockets.protocol.State.CLOSING`.
"""
class ConcurrencyError(WebSocketException, RuntimeError):
"""
Raised when receiving or sending messages concurrently.
WebSocket is a connection-oriented protocol. Reads must be serialized; so
must be writes. However, reading and writing concurrently is possible.
"""
# At the bottom to break import cycles created by type annotations.
from . import frames, http11 # noqa: E402
lazy_import(
globals(),
deprecated_aliases={
# deprecated in 14.0 - 2024-11-09
"AbortHandshake": ".legacy.exceptions",
"InvalidStatusCode": ".legacy.exceptions",
"RedirectHandshake": ".legacy.exceptions",
"WebSocketProtocolError": ".legacy.exceptions",
},
)
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