Improve password reset rate limit.

Used django-ratelimit instead of django-ratelimit-backend
to configure two different rate limit configurations for same
endpoint.

PROD-1708

common/djangoapps/util/request_rate_limiter.py

@@ -3,9 +3,6 @@ A utility class which wraps the RateLimitMixin 3rd party class to do bad request
 which can be used for rate limiting
 """
 
-from datetime import datetime, timedelta
-
-from django.conf import settings
 from ratelimitbackend.backends import RateLimitMixin
 
 
@@ -32,72 +29,3 @@ class BadRequestRateLimiter(RequestRateLimiter):
     Default rate limit is 30 requests for every 5 minutes.
     """
     pass
-
-
-class PasswordResetEmailRateLimiter(RequestRateLimiter):
-    """
-    Rate limiting requests to send password reset emails.
-    """
-    email_rate_limit = getattr(settings, 'PASSWORD_RESET_EMAIL_RATE_LIMIT', {})
-    requests = email_rate_limit.get('no_of_emails', 1)
-    cache_timeout_seconds = email_rate_limit.get('per_seconds', 60)
-    reset_email_cache_prefix = 'resetemail'
-
-    def key(self, request, dt):
-        """
-        Returns IP based cache key.
-        """
-        return '%s-%s-%s' % (
-            self.reset_email_cache_prefix,
-            self.get_ip(request),
-            dt.strftime('%Y%m%d%H%M'),
-        )
-
-    def email_key(self, request, dt):
-        """
-        Returns email based cache key.
-        """
-        return '%s-%s-%s' % (
-            self.reset_email_cache_prefix,
-            self.get_email(request),
-            dt.strftime('%Y%m%d%H%M'),
-        )
-
-    def expire_after(self):
-        """
-        Returns timeout for cache keys.
-        """
-        return self.cache_timeout_seconds
-
-    def get_email(self, request):
-        """
-        Returns email id for cache key.
-        """
-        user = request.user
-        # Prefer logged-in user's email
-        email = user.email if user.is_authenticated else request.POST.get('email')
-        return email
-
-    def keys_to_check(self, request):
-        """
-        Return list of IP and email based keys.
-        """
-        keys = super(PasswordResetEmailRateLimiter, self).keys_to_check(request)
-
-        now = datetime.now()
-        email_keys = [
-            self.email_key(
-                request,
-                now - timedelta(minutes=minute),
-            ) for minute in range(self.minutes + 1)
-        ]
-        keys.extend(email_keys)
-
-        return keys
-
-    def tick_request_counter(self, request):
-        """
-        Ticks any counters used to compute when rate limit has been reached.
-        """
-        for key in self.keys_to_check(request):
-            self.cache_incr(key)