mirror of
https://github.com/SickGear/SickGear.git
synced 2024-11-26 22:53:38 +00:00
139 lines
4.1 KiB
Python
139 lines
4.1 KiB
Python
# SPDX-FileCopyrightText: 2015 Eric Larson
|
|
#
|
|
# SPDX-License-Identifier: Apache-2.0
|
|
|
|
import calendar
|
|
import time
|
|
|
|
from email.utils import formatdate, parsedate, parsedate_tz
|
|
|
|
from datetime import datetime, timedelta
|
|
|
|
TIME_FMT = "%a, %d %b %Y %H:%M:%S GMT"
|
|
|
|
|
|
def expire_after(delta, date=None):
|
|
date = date or datetime.utcnow()
|
|
return date + delta
|
|
|
|
|
|
def datetime_to_header(dt):
|
|
return formatdate(calendar.timegm(dt.timetuple()))
|
|
|
|
|
|
class BaseHeuristic(object):
|
|
|
|
def warning(self, response):
|
|
"""
|
|
Return a valid 1xx warning header value describing the cache
|
|
adjustments.
|
|
|
|
The response is provided too allow warnings like 113
|
|
http://tools.ietf.org/html/rfc7234#section-5.5.4 where we need
|
|
to explicitly say response is over 24 hours old.
|
|
"""
|
|
return '110 - "Response is Stale"'
|
|
|
|
def update_headers(self, response):
|
|
"""Update the response headers with any new headers.
|
|
|
|
NOTE: This SHOULD always include some Warning header to
|
|
signify that the response was cached by the client, not
|
|
by way of the provided headers.
|
|
"""
|
|
return {}
|
|
|
|
def apply(self, response):
|
|
updated_headers = self.update_headers(response)
|
|
|
|
if updated_headers:
|
|
response.headers.update(updated_headers)
|
|
warning_header_value = self.warning(response)
|
|
if warning_header_value is not None:
|
|
response.headers.update({"Warning": warning_header_value})
|
|
|
|
return response
|
|
|
|
|
|
class OneDayCache(BaseHeuristic):
|
|
"""
|
|
Cache the response by providing an expires 1 day in the
|
|
future.
|
|
"""
|
|
|
|
def update_headers(self, response):
|
|
headers = {}
|
|
|
|
if "expires" not in response.headers:
|
|
date = parsedate(response.headers["date"])
|
|
expires = expire_after(timedelta(days=1), date=datetime(*date[:6]))
|
|
headers["expires"] = datetime_to_header(expires)
|
|
headers["cache-control"] = "public"
|
|
return headers
|
|
|
|
|
|
class ExpiresAfter(BaseHeuristic):
|
|
"""
|
|
Cache **all** requests for a defined time period.
|
|
"""
|
|
|
|
def __init__(self, **kw):
|
|
self.delta = timedelta(**kw)
|
|
|
|
def update_headers(self, response):
|
|
expires = expire_after(self.delta)
|
|
return {"expires": datetime_to_header(expires), "cache-control": "public"}
|
|
|
|
def warning(self, response):
|
|
tmpl = "110 - Automatically cached for %s. Response might be stale"
|
|
return tmpl % self.delta
|
|
|
|
|
|
class LastModified(BaseHeuristic):
|
|
"""
|
|
If there is no Expires header already, fall back on Last-Modified
|
|
using the heuristic from
|
|
http://tools.ietf.org/html/rfc7234#section-4.2.2
|
|
to calculate a reasonable value.
|
|
|
|
Firefox also does something like this per
|
|
https://developer.mozilla.org/en-US/docs/Web/HTTP/Caching_FAQ
|
|
http://lxr.mozilla.org/mozilla-release/source/netwerk/protocol/http/nsHttpResponseHead.cpp#397
|
|
Unlike mozilla we limit this to 24-hr.
|
|
"""
|
|
cacheable_by_default_statuses = {
|
|
200, 203, 204, 206, 300, 301, 404, 405, 410, 414, 501
|
|
}
|
|
|
|
def update_headers(self, resp):
|
|
headers = resp.headers
|
|
|
|
if "expires" in headers:
|
|
return {}
|
|
|
|
if "cache-control" in headers and headers["cache-control"] != "public":
|
|
return {}
|
|
|
|
if resp.status not in self.cacheable_by_default_statuses:
|
|
return {}
|
|
|
|
if "date" not in headers or "last-modified" not in headers:
|
|
return {}
|
|
|
|
date = calendar.timegm(parsedate_tz(headers["date"]))
|
|
last_modified = parsedate(headers["last-modified"])
|
|
if date is None or last_modified is None:
|
|
return {}
|
|
|
|
now = time.time()
|
|
current_age = max(0, now - date)
|
|
delta = date - calendar.timegm(last_modified)
|
|
freshness_lifetime = max(0, min(delta / 10, 24 * 3600))
|
|
if freshness_lifetime <= current_age:
|
|
return {}
|
|
|
|
expires = date + freshness_lifetime
|
|
return {"expires": time.strftime(TIME_FMT, time.gmtime(expires))}
|
|
|
|
def warning(self, resp):
|
|
return None
|