Fighting Rabbits

class WebFactionFixes(object):
    """
    Middleware that applies some fixes for people using
    the WebFaction hosting provider.  In particular:
 
    * sets 'REMOTE_ADDR' based on 'HTTP_X_FORWARDED_FOR', if the
      latter is set.
 
    * Monkey patches request.is_secure() to respect HTTP_X_FORWARDED_SSL.
      PLEASE NOTE that this is not reliable, since a user could set
      X-Forwarded-SSL manually and the main WebFaction Apache instance
      does not remove it, so it will appear to be a secure request
      when it is not.  Usually if they do that, they will be harming
      only themselves, but it depends how you use request.is_secure().
    """
    def process_request(self, request):
        # Fix REMOTE_ADDR
        try:
            real_ip = request.META['HTTP_X_FORWARDED_FOR']
        except KeyError:
            pass
        else:
            # HTTP_X_FORWARDED_FOR can be a comma-separated list of IPs. The
            # client's IP will be the first one.
            real_ip = real_ip.split(",")[0].strip()
            request.META['REMOTE_ADDR'] = real_ip
 
        # Fix HTTPS
        if 'HTTP_X_FORWARDED_SSL' in request.META:
            request.is_secure = lambda: request.META['HTTP_X_FORWARDED_SSL'] == 'on'