Source code for swh.web.api.throttling

# Copyright (C) 2017-2020  The Software Heritage developers
# See the AUTHORS file at the top-level directory of this distribution
# License: GNU Affero General Public License version 3, or any later version
# See top-level LICENSE file for more information

from ipaddress import ip_address, ip_network, IPv4Network, IPv6Network
from typing import Callable, List, TypeVar, Union

from django.core.exceptions import ImproperlyConfigured
import rest_framework
from rest_framework.throttling import ScopedRateThrottle
import sentry_sdk

from swh.web.config import get_config


APIView = TypeVar("APIView", bound="rest_framework.views.APIView")
Request = rest_framework.request.Request

API_THROTTLING_EXEMPTED_PERM = "swh.web.api.throttling_exempted"


[docs]class SwhWebRateThrottle(ScopedRateThrottle): """Custom request rate limiter for DRF enabling to exempt specific networks specified in swh-web configuration. Requests are grouped into scopes. It enables to apply different requests rate limiting based on the scope name but also the input HTTP request types. To associate a scope to requests, one must add a 'throttle_scope' attribute when using a class based view, or call the 'throttle_scope' decorator when using a function based view. By default, requests do not have an associated scope and are not rate limited. Rate limiting can also be configured according to the type of the input HTTP requests for fine grained tuning. For instance, the following YAML configuration section sets a rate of: - 1 per minute for POST requests - 60 per minute for other request types for the 'swh_api' scope while exempting those coming from the 127.0.0.0/8 ip network. .. code-block:: yaml throttling: scopes: swh_api: limiter_rate: default: 60/m POST: 1/m exempted_networks: - 127.0.0.0/8 """ scope = None def __init__(self): super().__init__() self.exempted_networks = None
[docs] def get_exempted_networks( self, scope_name: str ) -> List[Union[IPv4Network, IPv6Network]]: if not self.exempted_networks: scopes = get_config()["throttling"]["scopes"] scope = scopes.get(scope_name) if scope: networks = scope.get("exempted_networks") if networks: self.exempted_networks = [ ip_network(network) for network in networks ] return self.exempted_networks
[docs] def allow_request(self, request: Request, view: APIView) -> bool: # no throttling for staff users if request.user.is_authenticated and ( request.user.is_staff or request.user.has_perm(API_THROTTLING_EXEMPTED_PERM) ): return True # class based view case if not self.scope: default_scope = getattr(view, self.scope_attr, None) request_allowed = None if default_scope is not None: # check if there is a specific rate limiting associated # to the request type assert request.method is not None request_scope = f"{default_scope}_{request.method.lower()}" setattr(view, self.scope_attr, request_scope) try: request_allowed = super().allow_request(request, view) # use default rate limiting otherwise except ImproperlyConfigured as exc: sentry_sdk.capture_exception(exc) setattr(view, self.scope_attr, default_scope) if request_allowed is None: request_allowed = super().allow_request(request, view) # function based view case else: default_scope = self.scope # check if there is a specific rate limiting associated # to the request type self.scope = default_scope + "_" + request.method.lower() try: self.rate = self.get_rate() # use default rate limiting otherwise except ImproperlyConfigured as exc: sentry_sdk.capture_exception(exc) self.scope = default_scope self.rate = self.get_rate() self.num_requests, self.duration = self.parse_rate(self.rate) request_allowed = super(ScopedRateThrottle, self).allow_request( request, view ) self.scope = default_scope exempted_networks = self.get_exempted_networks(default_scope) exempted_ip = False if exempted_networks: remote_address = ip_address(self.get_ident(request)) exempted_ip = any( remote_address in network for network in exempted_networks ) request_allowed = exempted_ip or request_allowed # set throttling related data in the request metadata # in order for the ThrottlingHeadersMiddleware to # add X-RateLimit-* headers in the HTTP response if not exempted_ip and hasattr(self, "history"): hit_count = len(self.history) request.META["RateLimit-Limit"] = self.num_requests request.META["RateLimit-Remaining"] = self.num_requests - hit_count wait = self.wait() if wait is not None: request.META["RateLimit-Reset"] = int(self.now + wait) return request_allowed
[docs]def throttle_scope(scope: str) -> Callable[..., APIView]: """Decorator that allows the throttle scope of a DRF function based view to be set:: @api_view(['GET', ]) @throttle_scope('scope') def view(request): ... """ def decorator(func: APIView) -> APIView: SwhScopeRateThrottle = type( "CustomScopeRateThrottle", (SwhWebRateThrottle,), {"scope": scope} ) func.throttle_classes = (SwhScopeRateThrottle,) return func return decorator