Files
modbison/backend/app/rate_limit.py
T
daddy fb52c4fd08 PC3 Phase 3.3 fix: RATE_LIMIT_ENABLED flag so the smoke suite isn't throttled
Every checkpoint smoke test registers users against one backend from one
client IP, so the per-IP auth limit tripped mid-suite (main_menu_full_flow
-> 2/12). Add RATE_LIMIT_ENABLED (default true); run_checkpoint_tests.py
sets it false for its backend. test_rate_limit.py forces it on in-fixture
so the limiter is still really tested.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015jtxAiu5dAW4WxCNdGkrkJ
2026-09-05 22:22:52 +00:00

74 lines
2.4 KiB
Python

"""Lightweight in-process rate limiting.
The backend runs single-worker (required by the game-server supervisor), so a
process-local sliding-window counter is sufficient and needs no Redis. Keyed
by client IP. Used to blunt credential brute-force on the auth endpoints.
If the backend is ever scaled to multiple workers/hosts this must move to a
shared store (Redis) -- flagged here rather than silently under-enforcing.
"""
from __future__ import annotations
import time
from collections import defaultdict, deque
from fastapi import HTTPException, Request, status
from app.config import settings
class SlidingWindowLimiter:
def __init__(self, max_hits: int, window_seconds: float) -> None:
self.max_hits = max_hits
self.window = window_seconds
self._hits: dict[str, deque[float]] = defaultdict(deque)
def check(self, key: str) -> None:
now = time.monotonic()
q = self._hits[key]
cutoff = now - self.window
while q and q[0] < cutoff:
q.popleft()
if len(q) >= self.max_hits:
retry = max(1, int(q[0] + self.window - now))
raise HTTPException(
status_code=status.HTTP_429_TOO_MANY_REQUESTS,
detail="Too many attempts. Try again shortly.",
headers={"Retry-After": str(retry)},
)
q.append(now)
def reset(self) -> None:
self._hits.clear()
def _client_key(request: Request) -> str:
# X-Forwarded-For first hop when behind the reverse proxy, else the socket.
fwd = request.headers.get("x-forwarded-for", "")
if fwd:
return fwd.split(",")[0].strip()
return request.client.host if request.client else "unknown"
# 10 auth attempts / minute / IP -- generous for a human, painful for a
# brute-forcer.
_auth_limiter = SlidingWindowLimiter(max_hits=10, window_seconds=60)
async def auth_rate_limit(request: Request) -> None:
"""FastAPI dependency: rate-limit auth attempts per client IP.
A no-op when ``RATE_LIMIT_ENABLED`` is false -- the checkpoint smoke
suite runs every test against one backend from one client IP, so the
per-IP cap would trip mid-suite. The dedicated ``test_rate_limit``
module exercises the real behaviour regardless of this flag.
"""
if not settings.RATE_LIMIT_ENABLED:
return
_auth_limiter.check(f"auth:{_client_key(request)}")
def reset_all() -> None:
"""Test hook."""
_auth_limiter.reset()