mirror of
https://github.com/SickGear/SickGear.git
synced 2024-12-01 00:43:37 +00:00
373 lines
14 KiB
Python
373 lines
14 KiB
Python
"""
|
|
The httplib2 algorithms ported for use with requests.
|
|
"""
|
|
import logging
|
|
import re
|
|
import calendar
|
|
import time
|
|
from email.utils import parsedate_tz
|
|
|
|
from requests.structures import CaseInsensitiveDict
|
|
|
|
from .cache import DictCache
|
|
from .serialize import Serializer
|
|
|
|
|
|
logger = logging.getLogger(__name__)
|
|
|
|
URI = re.compile(r"^(([^:/?#]+):)?(//([^/?#]*))?([^?#]*)(\?([^#]*))?(#(.*))?")
|
|
|
|
|
|
def parse_uri(uri):
|
|
"""Parses a URI using the regex given in Appendix B of RFC 3986.
|
|
|
|
(scheme, authority, path, query, fragment) = parse_uri(uri)
|
|
"""
|
|
groups = URI.match(uri).groups()
|
|
return (groups[1], groups[3], groups[4], groups[6], groups[8])
|
|
|
|
|
|
class CacheController(object):
|
|
"""An interface to see if request should cached or not.
|
|
"""
|
|
def __init__(self, cache=None, cache_etags=True, serializer=None,
|
|
status_codes=None):
|
|
self.cache = cache or DictCache()
|
|
self.cache_etags = cache_etags
|
|
self.serializer = serializer or Serializer()
|
|
self.cacheable_status_codes = status_codes or (200, 203, 300, 301)
|
|
|
|
@classmethod
|
|
def _urlnorm(cls, uri):
|
|
"""Normalize the URL to create a safe key for the cache"""
|
|
(scheme, authority, path, query, fragment) = parse_uri(uri)
|
|
if not scheme or not authority:
|
|
raise Exception("Only absolute URIs are allowed. uri = %s" % uri)
|
|
|
|
scheme = scheme.lower()
|
|
authority = authority.lower()
|
|
|
|
if not path:
|
|
path = "/"
|
|
|
|
# Could do syntax based normalization of the URI before
|
|
# computing the digest. See Section 6.2.2 of Std 66.
|
|
request_uri = query and "?".join([path, query]) or path
|
|
defrag_uri = scheme + "://" + authority + request_uri
|
|
|
|
return defrag_uri
|
|
|
|
@classmethod
|
|
def cache_url(cls, uri):
|
|
return cls._urlnorm(uri)
|
|
|
|
def parse_cache_control(self, headers):
|
|
known_directives = {
|
|
# https://tools.ietf.org/html/rfc7234#section-5.2
|
|
'max-age': (int, True,),
|
|
'max-stale': (int, False,),
|
|
'min-fresh': (int, True,),
|
|
'no-cache': (None, False,),
|
|
'no-store': (None, False,),
|
|
'no-transform': (None, False,),
|
|
'only-if-cached' : (None, False,),
|
|
'must-revalidate': (None, False,),
|
|
'public': (None, False,),
|
|
'private': (None, False,),
|
|
'proxy-revalidate': (None, False,),
|
|
's-maxage': (int, True,)
|
|
}
|
|
|
|
cc_headers = headers.get('cache-control',
|
|
headers.get('Cache-Control', ''))
|
|
|
|
retval = {}
|
|
|
|
for cc_directive in cc_headers.split(','):
|
|
parts = cc_directive.split('=', 1)
|
|
directive = parts[0].strip()
|
|
|
|
try:
|
|
typ, required = known_directives[directive]
|
|
except KeyError:
|
|
logger.debug('Ignoring unknown cache-control directive: %s',
|
|
directive)
|
|
continue
|
|
|
|
if not typ or not required:
|
|
retval[directive] = None
|
|
if typ:
|
|
try:
|
|
retval[directive] = typ(parts[1].strip())
|
|
except IndexError:
|
|
if required:
|
|
logger.debug('Missing value for cache-control '
|
|
'directive: %s', directive)
|
|
except ValueError:
|
|
logger.debug('Invalid value for cache-control directive '
|
|
'%s, must be %s', directive, typ.__name__)
|
|
|
|
return retval
|
|
|
|
def cached_request(self, request):
|
|
"""
|
|
Return a cached response if it exists in the cache, otherwise
|
|
return False.
|
|
"""
|
|
cache_url = self.cache_url(request.url)
|
|
logger.debug('Looking up "%s" in the cache', cache_url)
|
|
cc = self.parse_cache_control(request.headers)
|
|
|
|
# Bail out if the request insists on fresh data
|
|
if 'no-cache' in cc:
|
|
logger.debug('Request header has "no-cache", cache bypassed')
|
|
return False
|
|
|
|
if 'max-age' in cc and cc['max-age'] == 0:
|
|
logger.debug('Request header has "max_age" as 0, cache bypassed')
|
|
return False
|
|
|
|
# Request allows serving from the cache, let's see if we find something
|
|
cache_data = self.cache.get(cache_url)
|
|
if cache_data is None:
|
|
logger.debug('No cache entry available')
|
|
return False
|
|
|
|
# Check whether it can be deserialized
|
|
resp = self.serializer.loads(request, cache_data)
|
|
if not resp:
|
|
logger.warning('Cache entry deserialization failed, entry ignored')
|
|
return False
|
|
|
|
# If we have a cached 301, return it immediately. We don't
|
|
# need to test our response for other headers b/c it is
|
|
# intrinsically "cacheable" as it is Permanent.
|
|
# See:
|
|
# https://tools.ietf.org/html/rfc7231#section-6.4.2
|
|
#
|
|
# Client can try to refresh the value by repeating the request
|
|
# with cache busting headers as usual (ie no-cache).
|
|
if resp.status == 301:
|
|
msg = ('Returning cached "301 Moved Permanently" response '
|
|
'(ignoring date and etag information)')
|
|
logger.debug(msg)
|
|
return resp
|
|
|
|
headers = CaseInsensitiveDict(resp.headers)
|
|
if not headers or 'date' not in headers:
|
|
if 'etag' not in headers:
|
|
# Without date or etag, the cached response can never be used
|
|
# and should be deleted.
|
|
logger.debug('Purging cached response: no date or etag')
|
|
self.cache.delete(cache_url)
|
|
logger.debug('Ignoring cached response: no date')
|
|
return False
|
|
|
|
now = time.time()
|
|
date = calendar.timegm(
|
|
parsedate_tz(headers['date'])
|
|
)
|
|
current_age = max(0, now - date)
|
|
logger.debug('Current age based on date: %i', current_age)
|
|
|
|
# TODO: There is an assumption that the result will be a
|
|
# urllib3 response object. This may not be best since we
|
|
# could probably avoid instantiating or constructing the
|
|
# response until we know we need it.
|
|
resp_cc = self.parse_cache_control(headers)
|
|
|
|
# determine freshness
|
|
freshness_lifetime = 0
|
|
|
|
# Check the max-age pragma in the cache control header
|
|
if 'max-age' in resp_cc:
|
|
freshness_lifetime = resp_cc['max-age']
|
|
logger.debug('Freshness lifetime from max-age: %i',
|
|
freshness_lifetime)
|
|
|
|
# If there isn't a max-age, check for an expires header
|
|
elif 'expires' in headers:
|
|
expires = parsedate_tz(headers['expires'])
|
|
if expires is not None:
|
|
expire_time = calendar.timegm(expires) - date
|
|
freshness_lifetime = max(0, expire_time)
|
|
logger.debug("Freshness lifetime from expires: %i",
|
|
freshness_lifetime)
|
|
|
|
# Determine if we are setting freshness limit in the
|
|
# request. Note, this overrides what was in the response.
|
|
if 'max-age' in cc:
|
|
freshness_lifetime = cc['max-age']
|
|
logger.debug('Freshness lifetime from request max-age: %i',
|
|
freshness_lifetime)
|
|
|
|
if 'min-fresh' in cc:
|
|
min_fresh = cc['min-fresh']
|
|
# adjust our current age by our min fresh
|
|
current_age += min_fresh
|
|
logger.debug('Adjusted current age from min-fresh: %i',
|
|
current_age)
|
|
|
|
# Return entry if it is fresh enough
|
|
if freshness_lifetime > current_age:
|
|
logger.debug('The response is "fresh", returning cached response')
|
|
logger.debug('%i > %i', freshness_lifetime, current_age)
|
|
return resp
|
|
|
|
# we're not fresh. If we don't have an Etag, clear it out
|
|
if 'etag' not in headers:
|
|
logger.debug(
|
|
'The cached response is "stale" with no etag, purging'
|
|
)
|
|
self.cache.delete(cache_url)
|
|
|
|
# return the original handler
|
|
return False
|
|
|
|
def conditional_headers(self, request):
|
|
cache_url = self.cache_url(request.url)
|
|
resp = self.serializer.loads(request, self.cache.get(cache_url))
|
|
new_headers = {}
|
|
|
|
if resp:
|
|
headers = CaseInsensitiveDict(resp.headers)
|
|
|
|
if 'etag' in headers:
|
|
new_headers['If-None-Match'] = headers['ETag']
|
|
|
|
if 'last-modified' in headers:
|
|
new_headers['If-Modified-Since'] = headers['Last-Modified']
|
|
|
|
return new_headers
|
|
|
|
def cache_response(self, request, response, body=None,
|
|
status_codes=None):
|
|
"""
|
|
Algorithm for caching requests.
|
|
|
|
This assumes a requests Response object.
|
|
"""
|
|
# From httplib2: Don't cache 206's since we aren't going to
|
|
# handle byte range requests
|
|
cacheable_status_codes = status_codes or self.cacheable_status_codes
|
|
if response.status not in cacheable_status_codes:
|
|
logger.debug(
|
|
'Status code %s not in %s',
|
|
response.status,
|
|
cacheable_status_codes
|
|
)
|
|
return
|
|
|
|
response_headers = CaseInsensitiveDict(response.headers)
|
|
|
|
# If we've been given a body, our response has a Content-Length, that
|
|
# Content-Length is valid then we can check to see if the body we've
|
|
# been given matches the expected size, and if it doesn't we'll just
|
|
# skip trying to cache it.
|
|
if (body is not None and
|
|
"content-length" in response_headers and
|
|
response_headers["content-length"].isdigit() and
|
|
int(response_headers["content-length"]) != len(body)):
|
|
return
|
|
|
|
cc_req = self.parse_cache_control(request.headers)
|
|
cc = self.parse_cache_control(response_headers)
|
|
|
|
cache_url = self.cache_url(request.url)
|
|
logger.debug('Updating cache with response from "%s"', cache_url)
|
|
|
|
# Delete it from the cache if we happen to have it stored there
|
|
no_store = False
|
|
if 'no-store' in cc:
|
|
no_store = True
|
|
logger.debug('Response header has "no-store"')
|
|
if 'no-store' in cc_req:
|
|
no_store = True
|
|
logger.debug('Request header has "no-store"')
|
|
if no_store and self.cache.get(cache_url):
|
|
logger.debug('Purging existing cache entry to honor "no-store"')
|
|
self.cache.delete(cache_url)
|
|
|
|
# If we've been given an etag, then keep the response
|
|
if self.cache_etags and 'etag' in response_headers:
|
|
logger.debug('Caching due to etag')
|
|
self.cache.set(
|
|
cache_url,
|
|
self.serializer.dumps(request, response, body=body),
|
|
)
|
|
|
|
# Add to the cache any 301s. We do this before looking that
|
|
# the Date headers.
|
|
elif response.status == 301:
|
|
logger.debug('Caching permanant redirect')
|
|
self.cache.set(
|
|
cache_url,
|
|
self.serializer.dumps(request, response)
|
|
)
|
|
|
|
# Add to the cache if the response headers demand it. If there
|
|
# is no date header then we can't do anything about expiring
|
|
# the cache.
|
|
elif 'date' in response_headers:
|
|
# cache when there is a max-age > 0
|
|
if 'max-age' in cc and cc['max-age'] > 0:
|
|
logger.debug('Caching b/c date exists and max-age > 0')
|
|
self.cache.set(
|
|
cache_url,
|
|
self.serializer.dumps(request, response, body=body),
|
|
)
|
|
|
|
# If the request can expire, it means we should cache it
|
|
# in the meantime.
|
|
elif 'expires' in response_headers:
|
|
if response_headers['expires']:
|
|
logger.debug('Caching b/c of expires header')
|
|
self.cache.set(
|
|
cache_url,
|
|
self.serializer.dumps(request, response, body=body),
|
|
)
|
|
|
|
def update_cached_response(self, request, response):
|
|
"""On a 304 we will get a new set of headers that we want to
|
|
update our cached value with, assuming we have one.
|
|
|
|
This should only ever be called when we've sent an ETag and
|
|
gotten a 304 as the response.
|
|
"""
|
|
cache_url = self.cache_url(request.url)
|
|
|
|
cached_response = self.serializer.loads(
|
|
request,
|
|
self.cache.get(cache_url)
|
|
)
|
|
|
|
if not cached_response:
|
|
# we didn't have a cached response
|
|
return response
|
|
|
|
# Lets update our headers with the headers from the new request:
|
|
# http://tools.ietf.org/html/draft-ietf-httpbis-p4-conditional-26#section-4.1
|
|
#
|
|
# The server isn't supposed to send headers that would make
|
|
# the cached body invalid. But... just in case, we'll be sure
|
|
# to strip out ones we know that might be problmatic due to
|
|
# typical assumptions.
|
|
excluded_headers = [
|
|
"content-length",
|
|
]
|
|
|
|
cached_response.headers.update(
|
|
dict((k, v) for k, v in response.headers.items()
|
|
if k.lower() not in excluded_headers)
|
|
)
|
|
|
|
# we want a 200 b/c we have content via the cache
|
|
cached_response.status = 200
|
|
|
|
# update our cache
|
|
self.cache.set(
|
|
cache_url,
|
|
self.serializer.dumps(request, cached_response),
|
|
)
|
|
|
|
return cached_response
|