Source code for edri.protocol.errors

from enum import IntEnum, unique

__all__ = ["ErrorReason", "ProtocolError"]




@unique
class ErrorReason(IntEnum):
    """Why a frame or handshake was rejected.

    The value travels in the payload of an ``ERROR`` frame, so a peer can tell
    "wrong secret" from "unreachable" — something closing the socket cannot
    express. Values are part of the wire format: append, never renumber.
    """

    BAD_VERSION = 1
    BAD_MAC = 2
    BAD_SEQ = 3
    TOO_LARGE = 4
    UNKNOWN_ROUTER = 5





class ProtocolError(Exception):
    """A frame could not be accepted. Always fatal for its connection."""

    def __init__(self, message: str, reason: ErrorReason, *, transport: bool = False) -> None:
        super().__init__(message)
        self.reason = reason
        # True when the failure is the socket closing under the handshake - a
        # Switch restart, a TCP reset, a rescheduled container - rather than a
        # MAC that was checked and failed. The Switch drops the connection
        # instead of sending a reason, so the two look identical on the wire;
        # this flag carries the distinction the wire cannot. It never travels
        # anywhere - unlike ``reason`` it is not part of the frame format.
        self.transport = transport