bedrock/mozorg/middleware.py

# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at https://mozilla.org/MPL/2.0/.

import time
from email.utils import formatdate

from django.conf import settings
from django.core.exceptions import MiddlewareNotUsed
from django.utils.cache import add_never_cache_headers


class CacheMiddleware:
    def __init__(self, get_response):
        self.get_response = get_response

    def __call__(self, request):
        response = self.get_response(request)
        return self.process_response(request, response)

    def process_response(self, request, response):
        if request.method not in ("GET", "HEAD"):
            return response
        if response.streaming or "cache-control" in response:
            return response

        # Expiration time in seconds, now + 10 minutes.
        stamp = int(time.time() + 600)

        response["Cache-Control"] = "max-age=600"
        response["Expires"] = formatdate(timeval=stamp, localtime=False, usegmt=True)
        return response


class ClacksOverheadMiddleware:
    # bug 1144901

    def __init__(self, get_response):
        self.get_response = get_response

    def __call__(self, request):
        response = self.get_response(request)
        return self.process_response(request, response)

    @staticmethod
    def process_response(request, response):
        if response.status_code == 200:
            response["X-Clacks-Overhead"] = "GNU Terry Pratchett"
        return response


class HostnameMiddleware:
    def __init__(self, get_response):
        if not settings.ENABLE_HOSTNAME_MIDDLEWARE:
            raise MiddlewareNotUsed

        values = [getattr(settings, x) for x in ["HOSTNAME", "CLUSTER_NAME"]]
        self.backend_server = ".".join(x for x in values if x)

        self.get_response = get_response

    def __call__(self, request):
        response = self.get_response(request)
        return self.process_response(request, response)

    def process_response(self, request, response):
        response["X-Backend-Server"] = self.backend_server
        return response


class VaryNoCacheMiddleware:
    def __init__(self, get_response):
        if not settings.ENABLE_VARY_NOCACHE_MIDDLEWARE:
            raise MiddlewareNotUsed
        self.get_response = get_response

    def __call__(self, request):
        response = self.get_response(request)
        return self.process_response(request, response)

    @staticmethod
    def process_response(request, response):
        if "vary" in response:
            path = request.path
            if path != "/" and not any(path.startswith(x) for x in settings.VARY_NOCACHE_EXEMPT_URL_PREFIXES):
                del response["vary"]
                del response["expires"]
                add_never_cache_headers(response)

        return response