http_middlewares.py

class MultipleProxyLastMiddleware(object):
    """
        Middleware to "fix" HTTP_X_FORWARDED_xxx headers for multiple proxy chains.
        Picks the *last* element in the proxy list
        As in Django docs - https://docs.djangoproject.com/en/1.3/ref/request-response/#django.http.HttpRequest.get_host
    """
    FORWARDED_FOR_FIELDS = [
        'HTTP_X_FORWARDED_FOR',
        'HTTP_X_FORWARDED_HOST',
        'HTTP_X_FORWARDED_SERVER',
    ]

    INDEX = -1
    
    def process_request(self, request):
        """
            Rewrites the proxy headers so that only the most recent proxy is used.
            Meaning of "recent" depends on the environment - it can be the last or first in the list, 
            in this case - the last one.
        """
        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[self.INDEX].strip()
                    

class MultipleProxyFirstMiddleware(MultipleProxyLastMiddleware):
    """
        Same as the MultipleProxyLastMiddleware except that it picks the *first* proxy from the list
        as the most recent one.
    """
    INDEX = 0