254 lines
9.5 KiB
Python
254 lines
9.5 KiB
Python
"""Local password accounts and opaque, revocable bearer sessions."""
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from __future__ import annotations
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import base64
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import binascii
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import hashlib
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import hmac
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import re
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import secrets
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import sqlite3
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import time
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from uuid import uuid4
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from app import database
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PASSWORD_ITERATIONS = 310_000
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SESSION_LIFETIME_SECONDS = 7 * 24 * 60 * 60
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LOGIN_FAILURE_LIMIT = 5
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LOGIN_WINDOW_SECONDS = 15 * 60
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REGISTRATION_LIMIT = 30
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REGISTRATION_WINDOW_SECONDS = 60 * 60
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_EMAIL_PATTERN = re.compile(r"^[^\s@]+@[^\s@]+\.[^\s@]+$")
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_DUMMY_SALT = bytes.fromhex("4f2bc994cb56a7a98b253a615fb57d2c")
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_DUMMY_DIGEST = hashlib.pbkdf2_hmac(
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"sha256", b"constant-time dummy password", _DUMMY_SALT, PASSWORD_ITERATIONS
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)
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def normalize_email(email: str) -> str:
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normalized = email.strip().casefold()
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if len(normalized) > 254 or not _EMAIL_PATTERN.fullmatch(normalized):
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raise ValueError("أدخل بريدًا إلكترونيًا صالحًا.")
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return normalized
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def _fingerprint(value: str) -> str:
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return hashlib.sha256(value.encode("utf-8", errors="replace")).hexdigest()
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def _rate_limit_keys(email: str, client_host: str) -> tuple[tuple[str, str], ...]:
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normalized = normalize_email(email)
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return (
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("login-email", _fingerprint(normalized)),
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("login-client", _fingerprint(client_host or "unknown")),
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)
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def login_retry_after(email: str, client_host: str, *, now: int | None = None) -> int:
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"""Return seconds until a login attempt is allowed, or zero when clear."""
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current = int(time.time()) if now is None else now
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retry = 0
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with database._connect() as connection:
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for scope, fingerprint in _rate_limit_keys(email, client_host):
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row = connection.execute(
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"SELECT window_started_at, attempts FROM auth_rate_limits WHERE scope=? AND fingerprint=?",
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(scope, fingerprint),
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).fetchone()
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if row is None or row["attempts"] < LOGIN_FAILURE_LIMIT:
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continue
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remaining = LOGIN_WINDOW_SECONDS - (current - row["window_started_at"])
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retry = max(retry, remaining)
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connection.execute(
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"DELETE FROM auth_rate_limits WHERE window_started_at + ? <= ?",
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(LOGIN_WINDOW_SECONDS, current),
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)
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return max(0, retry)
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def record_login_failure(email: str, client_host: str, *, now: int | None = None) -> None:
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current = int(time.time()) if now is None else now
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with database._connect() as connection:
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for scope, fingerprint in _rate_limit_keys(email, client_host):
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connection.execute(
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"""INSERT INTO auth_rate_limits(scope,fingerprint,window_started_at,attempts)
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VALUES(?,?,?,1)
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ON CONFLICT(scope,fingerprint) DO UPDATE SET
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window_started_at=CASE
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WHEN window_started_at + ? <= ? THEN ? ELSE window_started_at END,
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attempts=CASE
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WHEN window_started_at + ? <= ? THEN 1 ELSE attempts + 1 END""",
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(
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scope, fingerprint, current,
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LOGIN_WINDOW_SECONDS, current, current,
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LOGIN_WINDOW_SECONDS, current,
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),
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)
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def clear_login_failures(email: str, client_host: str) -> None:
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with database._connect() as connection:
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connection.executemany(
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"DELETE FROM auth_rate_limits WHERE scope=? AND fingerprint=?",
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_rate_limit_keys(email, client_host),
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)
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def registration_retry_after(client_host: str, *, now: int | None = None) -> int:
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return _retry_after(
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"register-client", client_host or "unknown", REGISTRATION_LIMIT,
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REGISTRATION_WINDOW_SECONDS, now=now,
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)
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def record_registration_attempt(client_host: str, *, now: int | None = None) -> None:
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_record_attempt(
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"register-client", client_host or "unknown", REGISTRATION_WINDOW_SECONDS,
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now=now,
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)
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def _retry_after(
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scope: str, value: str, limit: int, duration: int, *, now: int | None = None
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) -> int:
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current = int(time.time()) if now is None else now
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fingerprint = _fingerprint(value)
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with database._connect() as connection:
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row = connection.execute(
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"SELECT window_started_at,attempts FROM auth_rate_limits WHERE scope=? AND fingerprint=?",
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(scope, fingerprint),
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).fetchone()
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if row is None or row["attempts"] < limit:
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return 0
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return max(0, duration - (current - row["window_started_at"]))
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def _record_attempt(
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scope: str, value: str, duration: int, *, now: int | None = None
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) -> None:
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current = int(time.time()) if now is None else now
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fingerprint = _fingerprint(value)
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with database._connect() as connection:
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connection.execute(
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"""INSERT INTO auth_rate_limits(scope,fingerprint,window_started_at,attempts)
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VALUES(?,?,?,1)
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ON CONFLICT(scope,fingerprint) DO UPDATE SET
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window_started_at=CASE WHEN window_started_at + ? <= ? THEN ? ELSE window_started_at END,
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attempts=CASE WHEN window_started_at + ? <= ? THEN 1 ELSE attempts + 1 END""",
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(
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scope, fingerprint, current,
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duration, current, current,
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duration, current,
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),
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)
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def _hash_password(password: str) -> str:
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salt = secrets.token_bytes(16)
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digest = hashlib.pbkdf2_hmac(
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"sha256", password.encode("utf-8"), salt, PASSWORD_ITERATIONS
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)
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return "$".join(
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(
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"pbkdf2_sha256",
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str(PASSWORD_ITERATIONS),
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base64.urlsafe_b64encode(salt).decode("ascii"),
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base64.urlsafe_b64encode(digest).decode("ascii"),
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)
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)
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def _verify_password(password: str, encoded: str | None) -> bool:
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if encoded is None:
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salt, expected, iterations = _DUMMY_SALT, _DUMMY_DIGEST, PASSWORD_ITERATIONS
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else:
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try:
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algorithm, rounds, salt_text, digest_text = encoded.split("$", 3)
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iterations = int(rounds)
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if algorithm != "pbkdf2_sha256" or not 100_000 <= iterations <= 1_000_000:
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return False
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salt = base64.urlsafe_b64decode(salt_text.encode("ascii"))
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expected = base64.urlsafe_b64decode(digest_text.encode("ascii"))
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except (ValueError, UnicodeError, binascii.Error):
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return False
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actual = hashlib.pbkdf2_hmac(
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"sha256", password.encode("utf-8"), salt, iterations
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)
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return hmac.compare_digest(actual, expected)
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def create_account(email: str, password: str) -> str:
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normalized = normalize_email(email)
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if len(password) < 12 or len(password) > 256:
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raise ValueError("يجب أن تتراوح كلمة المرور بين 12 و256 محرفًا.")
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user_id = str(uuid4())
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password_hash = _hash_password(password)
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try:
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with database._connect() as connection:
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connection.execute("INSERT INTO users(id) VALUES (?)", (user_id,))
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connection.execute(
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"""INSERT INTO user_identities(user_id,provider,provider_subject,email,password_hash)
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VALUES(?, 'password', ?, ?, ?)""",
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(user_id, normalized, normalized, password_hash),
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)
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except sqlite3.IntegrityError as exc:
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raise ValueError("يوجد حساب مسجل بهذا البريد الإلكتروني.") from exc
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return user_id
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def authenticate(email: str, password: str) -> tuple[str, str] | None:
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normalized = normalize_email(email)
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with database._connect() as connection:
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row = connection.execute(
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"""SELECT user_id,password_hash FROM user_identities
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WHERE provider='password' AND provider_subject=?""",
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(normalized,),
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).fetchone()
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password_hash = row["password_hash"] if row is not None else None
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valid = _verify_password(password, password_hash)
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if row is None or not valid:
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return None
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return row["user_id"], normalized
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def issue_session(user_id: str) -> tuple[str, int]:
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token = secrets.token_urlsafe(32)
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expires_at = int(time.time()) + SESSION_LIFETIME_SECONDS
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token_hash = hashlib.sha256(token.encode("ascii")).hexdigest()
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with database._connect() as connection:
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connection.execute("DELETE FROM auth_sessions WHERE expires_at <= ?", (int(time.time()),))
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connection.execute(
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"INSERT INTO auth_sessions(token_hash,user_id,expires_at) VALUES(?,?,?)",
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(token_hash, user_id, expires_at),
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)
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return token, expires_at
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def resolve_session(token: str) -> str | None:
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if not token or len(token) > 256:
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return None
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token_hash = hashlib.sha256(token.encode("ascii", errors="ignore")).hexdigest()
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now = int(time.time())
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with database._connect() as connection:
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row = connection.execute(
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"SELECT user_id FROM auth_sessions WHERE token_hash=? AND expires_at>?",
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(token_hash, now),
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).fetchone()
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return row["user_id"] if row is not None else None
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def revoke_session(token: str) -> None:
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token_hash = hashlib.sha256(token.encode("ascii", errors="ignore")).hexdigest()
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with database._connect() as connection:
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connection.execute("DELETE FROM auth_sessions WHERE token_hash=?", (token_hash,))
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def account_email(user_id: str) -> str | None:
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with database._connect() as connection:
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row = connection.execute(
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"SELECT email FROM user_identities WHERE user_id=? AND provider='password'",
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(user_id,),
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).fetchone()
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return row["email"] if row is not None else None
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