'Get and store the map of resource records to domain names that
point to them.'

def get_route53_records(self):

    if self.boto_profile:
        r53_conn = route53.Route53Connection(profile_name=self.boto_profile)
    else:
        r53_conn = route53.Route53Connection()
    all_zones = r53_conn.get_zones()
    route53_zones = [zone for zone in all_zones if (zone.name[:(-1)] not in self.route53_excluded_zones)]
    self.route53_records = {}
    for zone in route53_zones:
        rrsets = r53_conn.get_all_rrsets(zone.id)
        for record_set in rrsets:
            record_name = record_set.name
            if record_name.endswith('.'):
                record_name = record_name[:(-1)]
            for resource in record_set.resource_records:
                self.route53_records.setdefault(resource, set())
                self.route53_records[resource].add(record_name)
