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#
# Ouroboros - Copyright (C) 2016 - 2026
#
# Python API for Ouroboros - Exceptions and errno translation
#
# Dimitri Staessens <dimitri@ouroboros.rocks>
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public License
# version 2.1 as published by the Free Software Foundation.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., http://www.fsf.org/about/contact/.
#
"""Exception hierarchy and errno translation for pyouroboros.
The hierarchy follows stdlib precedent (``socket``, ``ssl``, ``json``):
a single root :class:`OuroborosError`, semantically-named subclasses,
and multiple inheritance from Python builtins where the semantics
match (e.g. :class:`FlowTimeout` is a :class:`TimeoutError`).
"""
from __future__ import annotations
import errno
import os
from importlib.metadata import PackageNotFoundError, version
# Ouroboros-specific errno values, mirroring include/ouroboros/errno.h.
# Imported here (rather than via CFFI) so this module stays FFI-free
ENOTALLOC = 1000 # Flow is not allocated
EIPCPTYPE = 1001 # Unknown IPCP type
EIRMD = 1002 # Failed to communicate with IRMD
EIPCP = 1003 # Failed to communicate with IPCP
EIPCPSTATE = 1004 # Target in wrong state
EFLOWDOWN = 1005 # Flow is down
EFLOWPEER = 1006 # Flow is down (peer timed out)
ENAME = 1007 # Naming error
ECRYPT = 1008 # Encryption error
EAUTH = 1009 # Authentication error
EREPLAY = 1010 # OAP replay detected
# --- Root ---
class OuroborosError(Exception):
"""Base class for all pyouroboros exceptions."""
# --- IRM-side ---
class IrmError(OuroborosError):
"""Base class for IRM (control plane) errors."""
class IpcpCreateError(IrmError):
"""Raised when IPCP creation fails."""
class IpcpBootstrapError(IrmError):
"""Raised when IPCP bootstrapping fails."""
class IpcpEnrollError(IrmError):
"""Raised when IPCP enrollment fails."""
class IpcpConnectError(IrmError):
"""Raised when IPCP connection or disconnection fails."""
class IpcpTypeError(IrmError, ValueError):
"""Raised when an unknown IPCP type is encountered."""
class IpcpStateError(IrmError):
"""Raised when an IPCP/IRMd is in the wrong state for the request."""
class IrmdError(IrmError):
"""Raised when the IRM daemon is unreachable."""
class IpcpdError(IrmError):
"""Raised when the IPCP daemon is unreachable."""
class BindError(IrmError):
"""Raised when binding a program/process/IPCP to a name fails."""
class NameNotFoundError(IrmError):
"""Raised when a name lookup or unregister target does not exist."""
class NameExistsError(IrmError):
"""Raised when a name already exists."""
class InvalidNameError(IrmError, ValueError):
"""Raised when a name is malformed or otherwise invalid."""
# --- Flow / dev-side ---
class FlowError(OuroborosError):
"""Base class for flow-plane errors."""
class FlowAlreadyAllocatedError(FlowError):
"""Raised when allocating on a Flow that already holds an fd."""
class FlowNotAllocatedError(FlowError):
"""Raised when operating on a Flow that has no fd."""
class FlowDownError(FlowError, ConnectionError):
"""Raised when the flow has gone down."""
class FlowPeerError(FlowDownError):
"""Raised when the flow's peer has timed out."""
class FlowPermissionError(FlowError, PermissionError):
"""Raised when an operation is not permitted on the flow."""
class FlowTimeout(FlowError, TimeoutError):
"""Raised when a flow operation times out."""
class FlowCryptError(FlowError):
"""Raised on flow encryption errors."""
class FlowAuthError(FlowError):
"""Raised on flow authentication errors."""
class FlowReplayError(FlowError):
"""Raised when OAP replay is detected."""
class FlowEventError(FlowError):
"""Raised on errors from the flow event subsystem."""
class FlowDeallocWarning(Warning):
"""Warning issued when a deallocation reports a non-fatal problem."""
# --- errno translation ---
# Errno -> Python exception class. Errnos are in their canonical
# positive form here; raise_errno() flips the sign.
#
# Mapped errnos override the caller's `default=` argument, so we only
# map errnos whose semantics are unambiguous across both flow and IRM
# contexts. EPERM and EINVAL are intentionally NOT mapped: they can
# mean very different things on different operations, and a global
# mapping would silently override the call-site's chosen default (e.g.
# masking IpcpBootstrapError as a bare ValueError).
_ERRNO_MAP: dict[int, type[BaseException]] = {
errno.ETIMEDOUT: TimeoutError,
errno.EAGAIN: BlockingIOError,
errno.EWOULDBLOCK: BlockingIOError,
errno.ENOMEM: MemoryError,
errno.EACCES: PermissionError,
errno.ENOTCONN: ConnectionError,
errno.ECONNRESET: ConnectionResetError,
ENOTALLOC: FlowNotAllocatedError,
EIPCPTYPE: IpcpTypeError,
EIRMD: IrmdError,
EIPCP: IpcpdError,
EIPCPSTATE: IpcpStateError,
EFLOWDOWN: FlowDownError,
EFLOWPEER: FlowPeerError,
ENAME: NameNotFoundError,
ECRYPT: FlowCryptError,
EAUTH: FlowAuthError,
EREPLAY: FlowReplayError,
}
def _strerror(err: int) -> str:
if err >= 1000:
return _O7S_ERRNO_STR.get(err, f"ouroboros errno {err}")
return os.strerror(err)
_O7S_ERRNO_STR: dict[int, str] = {
ENOTALLOC: "flow is not allocated",
EIPCPTYPE: "unknown IPCP type",
EIRMD: "failed to communicate with IRMd",
EIPCP: "failed to communicate with IPCP",
EIPCPSTATE: "target in wrong state",
EFLOWDOWN: "flow is down",
EFLOWPEER: "flow peer timed out",
ENAME: "naming error",
ECRYPT: "encryption error",
EAUTH: "authentication error",
EREPLAY: "OAP replay detected",
}
def raise_errno(rc: int, default: type[OuroborosError] = FlowError) -> int:
"""Translate a non-negative-or-negative-errno return code.
Returns *rc* unchanged when it is non-negative. Otherwise raises
the mapped exception (or *default* if no mapping exists).
"""
if rc >= 0:
return rc
err = -rc
exc_cls = _ERRNO_MAP.get(err, default)
raise exc_cls(_strerror(err))
def check_ouroboros_version(o7s_major: int, o7s_minor: int) -> None:
"""Verify that the installed pyouroboros matches the linked library.
Compares *o7s_major*/*o7s_minor* (from
``OUROBOROS_VERSION_{MAJOR,MINOR}`` in the CFFI module) against
the installed pyouroboros distribution metadata. Silently returns
when running from a source tree without distribution metadata.
"""
try:
pyo7s_parts = version("PyOuroboros").split(".")
except PackageNotFoundError:
return
if o7s_major != int(pyo7s_parts[0]) or \
o7s_minor != int(pyo7s_parts[1]):
raise RuntimeError(
f"Ouroboros version mismatch: library is "
f"{o7s_major}.{o7s_minor}, pyouroboros is "
f"{pyo7s_parts[0]}.{pyo7s_parts[1]}"
)
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