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"""
Module: api.middleware.rate_limit
Description: Rate limiting middleware for API endpoints
Author: Anderson H. Silva
Date: 2025-01-25
License: Proprietary - All rights reserved
"""
from typing import Optional, Dict, Any
from datetime import datetime
from fastapi import Request, Response, HTTPException, status
from starlette.middleware.base import BaseHTTPMiddleware
from starlette.responses import JSONResponse
from src.core import get_logger
from src.infrastructure.rate_limiter import (
rate_limiter,
RateLimitTier,
RateLimitStrategy
)
from src.models.api_key import APIKey
logger = get_logger(__name__)
class RateLimitMiddleware(BaseHTTPMiddleware):
"""
Rate limiting middleware.
Supports multiple identification methods:
- API Key (preferred)
- User ID (authenticated users)
- IP Address (fallback)
"""
def __init__(
self,
app,
default_tier: RateLimitTier = RateLimitTier.FREE,
strategy: RateLimitStrategy = RateLimitStrategy.SLIDING_WINDOW
):
"""Initialize rate limit middleware."""
super().__init__(app)
self.default_tier = default_tier
self.rate_limiter = rate_limiter
self.rate_limiter.strategy = strategy
async def dispatch(self, request: Request, call_next):
"""Process request with rate limiting."""
# Skip rate limiting for certain paths
if self._should_skip(request.url.path):
return await call_next(request)
# Get rate limit key and tier
key, tier, custom_limits = self._get_rate_limit_info(request)
if not key:
# No identifier available, skip rate limiting
logger.warning(
"rate_limit_no_identifier",
path=request.url.path,
method=request.method
)
return await call_next(request)
# Check rate limit
try:
allowed, results = await self.rate_limiter.check_rate_limit(
key=key,
endpoint=request.url.path,
tier=tier,
custom_limits=custom_limits
)
if not allowed:
# Rate limit exceeded
headers = self.rate_limiter.get_headers(results)
# Find which limit was exceeded
exceeded_window = None
for window, data in results.items():
if not data.get("allowed", True):
exceeded_window = window
break
logger.warning(
"rate_limit_exceeded",
key=key,
endpoint=request.url.path,
window=exceeded_window,
tier=tier
)
return JSONResponse(
status_code=status.HTTP_429_TOO_MANY_REQUESTS,
content={
"detail": f"Rate limit exceeded for {exceeded_window}",
"error": "RATE_LIMIT_EXCEEDED",
"limits": results
},
headers=headers
)
# Add rate limit headers to response
response = await call_next(request)
# Add headers
headers = self.rate_limiter.get_headers(results)
for header, value in headers.items():
response.headers[header] = value
# Log high usage
for window, data in results.items():
if data["remaining"] < data["limit"] * 0.1: # Less than 10% remaining
logger.info(
"rate_limit_warning",
key=key,
endpoint=request.url.path,
window=window,
remaining=data["remaining"],
limit=data["limit"]
)
return response
except Exception as e:
logger.error(
"rate_limit_error",
error=str(e),
exc_info=True
)
# On error, allow request to proceed
return await call_next(request)
def _should_skip(self, path: str) -> bool:
"""Check if path should skip rate limiting."""
skip_paths = [
"/health",
"/metrics",
"/docs",
"/openapi.json",
"/favicon.ico",
"/_next", # Next.js assets
"/static",
]
for skip_path in skip_paths:
if path.startswith(skip_path):
return True
return False
def _get_rate_limit_info(
self,
request: Request
) -> tuple[Optional[str], RateLimitTier, Optional[Dict[str, int]]]:
"""
Get rate limit key, tier, and custom limits from request.
Returns:
Tuple of (key, tier, custom_limits)
"""
# Priority 1: API Key
api_key = getattr(request.state, "api_key", None)
if api_key and isinstance(api_key, APIKey):
key = f"api_key:{api_key.id}"
tier = RateLimitTier(api_key.tier)
# Get custom limits if set
custom_limits = {}
if api_key.rate_limit_per_minute:
custom_limits["per_minute"] = api_key.rate_limit_per_minute
if api_key.rate_limit_per_hour:
custom_limits["per_hour"] = api_key.rate_limit_per_hour
if api_key.rate_limit_per_day:
custom_limits["per_day"] = api_key.rate_limit_per_day
return key, tier, custom_limits if custom_limits else None
# Priority 2: Authenticated User
user_id = getattr(request.state, "user_id", None)
if user_id:
key = f"user:{user_id}"
# Check user role for tier
user = getattr(request.state, "user", {})
role = user.get("role", "").lower()
if role == "admin" or user.get("is_superuser"):
tier = RateLimitTier.UNLIMITED
elif role == "pro":
tier = RateLimitTier.PRO
elif role == "basic":
tier = RateLimitTier.BASIC
else:
tier = RateLimitTier.FREE
return key, tier, None
# Priority 3: IP Address
client_ip = None
if request.client:
client_ip = request.client.host
# Check for proxy headers
if not client_ip:
forwarded_for = request.headers.get("X-Forwarded-For")
if forwarded_for:
client_ip = forwarded_for.split(",")[0].strip()
if not client_ip:
real_ip = request.headers.get("X-Real-IP")
if real_ip:
client_ip = real_ip
if client_ip:
key = f"ip:{client_ip}"
return key, self.default_tier, None
return None, self.default_tier, None
def get_rate_limit_decorator(
tier: Optional[RateLimitTier] = None,
custom_limits: Optional[Dict[str, int]] = None
):
"""
Decorator for endpoint-specific rate limiting.
Usage:
@router.get("/expensive")
@rate_limit(tier=RateLimitTier.PRO, custom_limits={"per_minute": 5})
async def expensive_endpoint():
...
"""
def decorator(func):
# Store rate limit info on function
func._rate_limit_tier = tier
func._rate_limit_custom = custom_limits
return func
return decorator
# Convenience decorator
rate_limit = get_rate_limit_decorator |