mirror of
https://github.com/kuhyx/screen-locker.git
synced 2026-11-10 20:07:16 +01:00
Krzysztof kuhy Rudnicki
a826cfa166
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_018RHwVPyiiQMPh4M3JQwQku
94 lines
3.0 KiB
Python
94 lines
3.0 KiB
Python
"""The ID token and URL for the Firebase session stream.
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Split out of :mod:`screen_locker._session_stream` for the 250-line cap.
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Reuses crdt_sync's own token provider and the screen_locker credential cache
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(``~/.config/screen_locker/firebase_auth.json``); it never signs in with the
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password, which is stale -- only the cached refresh token authenticates. A
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missing session is healed the way the sync heals it,
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:func:`screen_locker._sync_client.try_recover_firebase_session`.
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"""
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from __future__ import annotations
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from dataclasses import dataclass
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from datetime import UTC, datetime, timedelta
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from typing import Final
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from crdt_sync import (
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ConfigError,
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FirebaseAuthError,
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FirebaseConfig,
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FirebaseTokenProvider,
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credential_store_for,
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)
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from crdt_sync._firebase import encode_path
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from screen_locker._sync_client import try_recover_firebase_session
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__all__ = ["StreamAuth", "StreamError", "stream_auth"]
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_APP: Final = "screen_locker"
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# Inside crdt_sync's 5-minute refresh skew, so the reconnect mints a new token
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# instead of being handed the dying one back.
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_RENEW_BEFORE_EXPIRY: Final = timedelta(minutes=4)
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_ASSUMED_LIFETIME: Final = timedelta(hours=1)
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class StreamError(Exception):
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"""One stream connection failed in a way that warrants backing off."""
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@dataclass(frozen=True)
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class StreamAuth:
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"""Where to stream from, with which token, and when to renew it."""
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url: str
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token: str
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renew_at: datetime
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def _provider(config: FirebaseConfig) -> FirebaseTokenProvider:
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"""A provider over the cached session, recovering one if there is none.
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Raises:
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StreamError: No cached session, and recovery failed too.
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"""
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store = credential_store_for(_APP)
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auth = FirebaseTokenProvider(config.api_key, store)
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if auth.has_session():
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return auth
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recovery = try_recover_firebase_session()
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if not recovery.recovered:
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msg = f"no cached Firebase session and recovery failed: {recovery.reason}"
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raise StreamError(msg)
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return FirebaseTokenProvider(config.api_key, store)
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def stream_auth(path: str) -> StreamAuth:
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"""A fresh token for streaming ``path`` (a logical RTDB path).
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A new provider per call re-reads the cache, so a token the 15-min sync
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refreshed in the meantime is picked up rather than refreshed again.
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Raises:
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StreamError: The config, the session or the token is unusable.
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"""
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try:
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config = FirebaseConfig.load()
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except ConfigError as exc:
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msg = f"Firebase config unusable: {exc}"
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raise StreamError(msg) from exc
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auth = _provider(config)
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try:
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token = auth.id_token()
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except FirebaseAuthError as exc:
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msg = f"could not get an ID token: {exc}"
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raise StreamError(msg) from exc
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saved = credential_store_for(_APP).load()
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expires = saved.expires_at if saved else datetime.now(UTC) + _ASSUMED_LIFETIME
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return StreamAuth(
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url=f"{config.database_url.rstrip('/')}/{encode_path(path)}.json",
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token=token,
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renew_at=expires - _RENEW_BEFORE_EXPIRY,
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)
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