dynamicweb/utils/middleware.py

class MultipleProxyMiddleware(object):
    FORWARDED_FOR_FIELDS = [
        'HTTP_X_FORWARDED_FOR',
        'HTTP_X_FORWARDED_HOST',
        'HTTP_X_FORWARDED_SERVER',
    ]

    def process_request(self, request):
        """
        Rewrites the proxy headers so that only the most
        recent proxy is used.
        """
        for field in self.FORWARDED_FOR_FIELDS:
            if field in request.META:
                if ',' in request.META[field]:
                    parts = request.META[field].split(',')
                    request.META[field] = parts[-1].strip()