code: def endpoint(request):
      if request.method != 'POST':
          raise Http404
      if hasattr(settings, 'BOUNCY_TOPIC_ARN'):
          if 'HTTP_X_AMZ_SNS_TOPIC_ARN' not in request.META:
              return HttpResponseBadRequest('No TopicArn Header')
          if (not request.META['HTTP_X_AMZ_SNS_TOPIC_ARN']
                  in settings.BOUNCY_TOPIC_ARN):
              return HttpResponseBadRequest('Bad Topic')
      if isinstance(request.body, str):
          request_body = request.body
      else:
          request_body = request.body.decode()
      try:
          data = json.loads(request_body)
      except ValueError:
          logger.warning('Notification Not Valid JSON: {}'.format(request_body))
          return HttpResponseBadRequest('Not Valid JSON')
      if not set(VITAL_NOTIFICATION_FIELDS) <= set(data):
          logger.warning('Request Missing Necessary Keys')
          return HttpResponseBadRequest('Request Missing Necessary Keys')
      if not data['Type'] in ALLOWED_TYPES:
          logger.info('Notification Type Not Known %s', data['Type'])
          return HttpResponseBadRequest('Unknown Notification Type')
      domain = urlparse(data['SigningCertURL']).netloc
      pattern = getattr(
          settings, 'BOUNCY_CERT_DOMAIN_REGEX', r"sns.[a-z0-9\-]+.amazonaws.com$"
      )
      if not re.search(pattern, domain):
          logger.warning(
              'Improper Certificate Location %s', data['SigningCertURL'])
          return HttpResponseBadRequest('Improper Certificate Location')
      if (getattr(settings, 'BOUNCY_VERIFY_CERTIFICATE', True)
              and not verify_notification(data)):
          logger.error('Verification Failure %s', )
          return HttpResponseBadRequest('Improper Signature')
      signals.notification.send(
          sender='bouncy_endpoint', notification=data, request=request)
      if data['Type'] == 'SubscriptionConfirmation':
          if not getattr(settings, 'BOUNCY_AUTO_SUBSCRIBE', True):
              raise Http404
          return approve_subscription(data)
      elif data['Type'] == 'UnsubscribeConfirmation':
          logger.info('UnsubscribeConfirmation Not Handled')
          return HttpResponse('UnsubscribeConfirmation Not Handled')
      try:
          message = json.loads(data['Message'])
      except ValueError:
          logger.info('Non-Valid JSON Message Received')
          return HttpResponse('Message is not valid JSON')
      return process_message(message, data)