import hashlib import time from typing import Dict, List, Optional, Tuple from django.core.cache import cache as default_cache from django.core.exceptions import ImproperlyConfigured from django.http import HttpRequest class BaseThrottle: """ Rate throttling of requests. """ def allow_request(self, request: HttpRequest) -> bool: """ Return `True` if the request should be allowed, `False` otherwise. """ raise NotImplementedError(".allow_request() must be overridden") def get_ident(self, request: HttpRequest) -> Optional[str]: """ Identify the machine making the request by parsing HTTP_X_FORWARDED_FOR if present and number of proxies is > 0. If not use all of HTTP_X_FORWARDED_FOR if it is available, if not use REMOTE_ADDR. """ from ninja.conf import settings xff = request.META.get("HTTP_X_FORWARDED_FOR") remote_addr = request.META.get("REMOTE_ADDR") num_proxies = settings.NUM_PROXIES if num_proxies is not None: if num_proxies == 0 or xff is None: return remote_addr addrs: List[str] = xff.split(",") client_addr = addrs[-min(num_proxies, len(addrs))] return client_addr.strip() return "".join(xff.split()) if xff else remote_addr def wait(self) -> Optional[float]: """ Optionally, return a recommended number of seconds to wait before the next request. """ return None class SimpleRateThrottle(BaseThrottle): """ A simple cache implementation, that only requires `.get_cache_key()` to be overridden. The rate (requests / seconds) is set by a `rate` attribute on the Throttle class. The attribute is a string of the form 'number_of_requests/period'. Period should be one of: ('s', 'sec', 'm', 'min', 'h', 'hour', 'd', 'day') Previous request information used for throttling is stored in the cache. """ from ninja.conf import settings cache = default_cache timer = time.time cache_format = "throttle_%(scope)s_%(ident)s" scope: Optional[str] = None THROTTLE_RATES: Dict[str, Optional[str]] = settings.DEFAULT_THROTTLE_RATES _PERIODS = { "s": 1, "m": 60, "h": 60 * 60, "d": 60 * 60 * 24, "sec": 1, "min": 60, "hour": 60 * 60, "day": 60 * 60 * 24, } def __init__(self, rate: Optional[str] = None): self.rate: Optional[str] if rate: self.rate = rate else: self.rate = self.get_rate() self.num_requests, self.duration = self.parse_rate(self.rate) def get_cache_key(self, request: HttpRequest) -> Optional[str]: """ Should return a unique cache-key which can be used for throttling. Must be overridden. May return `None` if the request should not be throttled. """ raise NotImplementedError(".get_cache_key() must be overridden") def get_rate(self) -> Optional[str]: """ Determine the string representation of the allowed request rate. """ if not getattr(self, "scope", None): msg = f"You must set either `.scope` or `.rate` for '{self.__class__.__name__}' throttle" raise ImproperlyConfigured(msg) try: return self.THROTTLE_RATES[self.scope] # type: ignore except KeyError: msg = f"No default throttle rate set for '{self.scope}' scope" raise ImproperlyConfigured(msg) from None def parse_rate(self, rate: Optional[str]) -> Tuple[Optional[int], Optional[int]]: """ Given the request rate string, return a two tuple of: , """ if rate is None: return (None, None) try: count, rest = rate.split("/", 1) for unit in self._PERIODS: if rest.endswith(unit): multi = int(rest[: -len(unit)]) if rest[: -len(unit)] else 1 period = self._PERIODS[unit] break else: multi, period = int(rest), 1 return int(count), multi * period except (ValueError, IndexError): raise ValueError(f"Invalid rate format: {rate}") from None def allow_request(self, request: HttpRequest) -> bool: """ Implement the check to see if the request should be throttled. On success calls `throttle_success`. On failure calls `throttle_failure`. """ # if self.rate is None: # return True self.key = self.get_cache_key(request) if self.key is None: return True self.history = self.cache.get(self.key, []) self.now = self.timer() # type: ignore # Drop any requests from the history which have now passed the # throttle duration while self.history and self.history[-1] <= self.now - self.duration: # type: ignore self.history.pop() if len(self.history) >= self.num_requests: # type: ignore return self.throttle_failure() return self.throttle_success() def throttle_success(self) -> bool: """ Inserts the current request's timestamp along with the key into the cache. """ self.history.insert(0, self.now) self.cache.set(self.key, self.history, self.duration) return True def throttle_failure(self) -> bool: """ Called when a request to the API has failed due to throttling. """ return False def wait(self) -> Optional[float]: """ Returns the recommended next request time in seconds. """ if self.history: remaining_duration = self.duration - (self.now - self.history[-1]) else: remaining_duration = self.duration available_requests = self.num_requests - len(self.history) + 1 # type: ignore if available_requests <= 0: return None return remaining_duration / float(available_requests) # type: ignore class AnonRateThrottle(SimpleRateThrottle): """ Limits the rate of API calls that may be made by a anonymous users. The IP address of the request will be used as the unique cache key. """ scope = "anon" def get_cache_key(self, request: HttpRequest) -> Optional[str]: if getattr(request, "auth", None) is not None: return None # Only throttle unauthenticated requests. return self.cache_format % { "scope": self.scope, "ident": self.get_ident(request), } class AuthRateThrottle(SimpleRateThrottle): """ Limits the rate of API calls that may be made by a given user. The string representation of request.auth object will be used as a unique cache key. If you use custom auth objects make sure to implement __str__ method. For anonymous requests, the IP address of the request will be used. """ scope = "auth" def get_cache_key(self, request: HttpRequest) -> str: if getattr(request, "auth", None) is not None: ident = hashlib.sha256(str(request.auth).encode()).hexdigest() # type: ignore # TODO: ^maybe auth should have an attribute that developer can overwrite else: ident = self.get_ident(request) # type: ignore return self.cache_format % {"scope": self.scope, "ident": ident} class UserRateThrottle(SimpleRateThrottle): """ Limits the rate of API calls that may be made by a given user. The user id will be used as a unique cache key if the user is authenticated. For anonymous requests, the IP address of the request will be used. """ scope = "user" def get_cache_key(self, request: HttpRequest) -> str: if request.user and request.user.is_authenticated: ident = request.user.pk else: ident = self.get_ident(request) return self.cache_format % {"scope": self.scope, "ident": ident}