django bruteforce

"""
Usage:

An example of adding the bruteforce() function to a custom authentication backend:

from django.contrib.auth.backends import ModelBackend
from django.contrib.auth.models import User

from bruteforce import bruteforce

class EmailBackend(ModelBackend):
    def authenticate(self, username=None, password=None):
        try:
            user = User.objects.get(email=username)
            if user.check_password(password):
                return user
        except User.DoesNotExist:
            pass

        # bruteforce
        if username is not None:
            bruteforce(username)
        return None

"""
import datetime
import hashlib
from time import sleep

from django.conf import settings
from django.core.cache import cache
#https://raw.githubusercontent.com/naremit/NaremitBruteforce/master/bruteforce.py
# settings
BRUTEFORCE_MINUTES = getattr(settings, 'BRUTEFORCE_MINUTES', 5)
BRUTEFORCE_ALLOWED_ATTEMPTS = getattr(settings, 'BRUTEFORCE_ALLOWED_ATTEMPTS', 3)
BRUTEFORCE_MAX_PAUSE = getattr(settings, 'BRUTEFORCE_MAX_PAUSE', 10)
BRUTEFORCE_PREFIX = getattr(settings, 'BRUTEFORCE_PREFIX', 'bruteforce')

def bruteforce(ident):
    # hash the identifier to prevent control character problems
    prefix = '%s_%s' % (BRUTEFORCE_PREFIX, hashlib.md5(ident).hexdigest())

    # create cache keys for each of the last n minutes
    cache_keys = []
    dt = datetime.datetime.now()
    count = 0
    while count < BRUTEFORCE_MINUTES:
        cache_keys.append('%s_%s:%s' % (prefix, dt.hour, dt.minute))
        dt -= datetime.timedelta(seconds=60)
        count +=1

    # increment count for this minute
    try:
        cache.incr(cache_keys[0])
    except:
        cache.set(cache_keys[0], 1, (60 * (BRUTEFORCE_MINUTES + 1)))

    # collect count from cache
    attempt_count = 0
    attempt_dict = cache.get_many(cache_keys)
    for v in attempt_dict.itervalues():
        attempt_count += v

    # if we detect multiple attempts, sleep
    sleep(min(
        BRUTEFORCE_MAX_PAUSE,
        max(0, attempt_count - BRUTEFORCE_ALLOWED_ATTEMPTS)
    ))