django-cidr.py

from django.conf import settings

def get_client_ip(request):
    x_forwarded_for = request.META.get('HTTP_X_FORWARDED_FOR')
    if x_forwarded_for:
        ip = x_forwarded_for.split(',')[0]
    else:
        ip = request.META.get('REMOTE_ADDR')
    return ip


def test_ip_in_range(request):
    client_ip = get_client_ip(request)
    byte_to_bits = lambda b: bin(int(b))[2:].rjust(8, '0')
    ip_to_bits = lambda ip: ''.join([byte_to_bits(b) for b in ip.split('.')])
    client_ip_bits = ip_to_bits(client_ip)
    for net in settings.GITHUB_WEBHOOK_IPS:
        ip, snet = net.split('/')
        ip_bits = ip_to_bits(ip)
        if client_ip_bits[:int(snet)] == ip_bits[:int(snet)]:
            return True
    return False