mirror of
https://github.com/moparisthebest/SickRage
synced 2024-08-13 16:53:54 -04:00
255 lines
8.9 KiB
Python
255 lines
8.9 KiB
Python
"""
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The httplib2 algorithms ported for use with requests.
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"""
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import re
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import calendar
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import time
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import os
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from cachecontrol.cache import DictCache
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from cachecontrol.compat import parsedate_tz
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URI = re.compile(r"^(([^:/?#]+):)?(//([^/?#]*))?([^?#]*)(\?([^#]*))?(#(.*))?")
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def parse_uri(uri):
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"""Parses a URI using the regex given in Appendix B of RFC 3986.
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(scheme, authority, path, query, fragment) = parse_uri(uri)
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"""
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groups = URI.match(uri).groups()
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return (groups[1], groups[3], groups[4], groups[6], groups[8])
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class CacheController(object):
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"""An interface to see if request should cached or not.
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"""
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def __init__(self, cache=None, cache_etags=True, cache_force=False):
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self.cache = cache or DictCache()
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self.cache_etags = cache_etags
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self.cache_force = cache_force
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def _urlnorm(self, uri):
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"""Normalize the URL to create a safe key for the cache"""
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(scheme, authority, path, query, fragment) = parse_uri(uri)
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if not scheme or not authority:
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raise Exception("Only absolute URIs are allowed. uri = %s" % uri)
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authority = authority.lower()
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scheme = scheme.lower()
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if not path:
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path = "/"
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# Could do syntax based normalization of the URI before
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# computing the digest. See Section 6.2.2 of Std 66.
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request_uri = query and "?".join([path, query]) or path
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scheme = scheme.lower()
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defrag_uri = scheme + "://" + authority + request_uri
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return defrag_uri
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def cache_url(self, uri):
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return self._urlnorm(uri)
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def parse_cache_control(self, headers):
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"""
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Parse the cache control headers returning a dictionary with values
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for the different directives.
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"""
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retval = {}
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cc_header = 'cache-control'
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if 'Cache-Control' in headers:
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cc_header = 'Cache-Control'
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if cc_header in headers:
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parts = headers[cc_header].split(',')
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parts_with_args = [
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tuple([x.strip().lower() for x in part.split("=", 1)])
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for part in parts if -1 != part.find("=")]
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parts_wo_args = [(name.strip().lower(), 1)
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for name in parts if -1 == name.find("=")]
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retval = dict(parts_with_args + parts_wo_args)
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return retval
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def cached_request(self, url, headers):
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cache_url = self.cache_url(url)
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cc = self.parse_cache_control(headers)
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# non-caching states
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no_cache = True if 'no-cache' in cc else False
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if 'max-age' in cc and cc['max-age'] == 0:
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no_cache = True
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# see if it is in the cache anyways
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in_cache = self.cache.get(cache_url)
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if no_cache or not in_cache:
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return False
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# It is in the cache, so lets see if it is going to be
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# fresh enough
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resp = self.cache.get(cache_url)
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# Check our Vary header to make sure our request headers match
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# up. We don't delete it from the though, we just don't return
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# our cached value.
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#
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# NOTE: Because httplib2 stores raw content, it denotes
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# headers that were sent in the original response by
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# adding -varied-$name. We don't have to do that b/c we
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# are storing the object which has a reference to the
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# original request. If that changes, then I'd propose
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# using the varied headers in the cache key to avoid the
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# situation all together.
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if 'vary' in resp.headers:
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varied_headers = resp.headers['vary'].replace(' ', '').split(',')
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original_headers = resp.request.headers
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for header in varied_headers:
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# If our headers don't match for the headers listed in
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# the vary header, then don't use the cached response
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if headers.get(header, None) != original_headers.get(header):
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return False
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now = time.time()
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date = calendar.timegm(
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parsedate_tz(resp.headers['date'])
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)
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current_age = max(0, now - date)
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# TODO: There is an assumption that the result will be a
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# requests response object. This may not be best since we
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# could probably avoid instantiating or constructing the
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# response until we know we need it.
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resp_cc = self.parse_cache_control(resp.headers)
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# determine freshness
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freshness_lifetime = 0
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if 'max-age' in resp_cc and resp_cc['max-age'].isdigit():
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freshness_lifetime = int(resp_cc['max-age'])
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elif 'expires' in resp.headers:
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expires = parsedate_tz(resp.headers['expires'])
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if expires is not None:
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expire_time = calendar.timegm(expires) - date
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freshness_lifetime = max(0, expire_time)
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# determine if we are setting freshness limit in the req
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if 'max-age' in cc:
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try:
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freshness_lifetime = int(cc['max-age'])
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except ValueError:
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freshness_lifetime = 0
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if 'min-fresh' in cc:
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try:
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min_fresh = int(cc['min-fresh'])
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except ValueError:
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min_fresh = 0
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# adjust our current age by our min fresh
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current_age += min_fresh
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# see how fresh we actually are
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fresh = (freshness_lifetime > current_age)
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if fresh:
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# make sure we set the from_cache to true
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resp.from_cache = True
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return resp
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# we're not fresh. If we don't have an Etag, clear it out
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if 'etag' not in resp.headers:
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self.cache.delete(cache_url)
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if 'etag' in resp.headers:
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headers['If-None-Match'] = resp.headers['ETag']
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if 'last-modified' in resp.headers:
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headers['If-Modified-Since'] = resp.headers['Last-Modified']
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# return the original handler
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return False
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def add_headers(self, url, resp=None):
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resp = self.cache.get(url)
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if resp and 'etag' in resp.headers:
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return {'If-None-Match': resp.headers['etag']}
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return {}
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def cache_response(self, request, resp):
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"""
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Algorithm for caching requests.
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This assumes a requests Response object.
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"""
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# From httplib2: Don't cache 206's since we aren't going to
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# handle byte range requests
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if resp.status_code not in [200, 203]:
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return
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cc_req = self.parse_cache_control(request.headers)
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cc = self.parse_cache_control(resp.headers)
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cache_url = self.cache_url(request.url)
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# Delete it from the cache if we happen to have it stored there
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no_store = cc.get('no-store') or cc_req.get('no-store')
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if no_store and self.cache.get(cache_url):
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self.cache.delete(cache_url)
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# If we've been given an etag, then keep the response
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if self.cache_etags and 'etag' in resp.headers:
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self.cache.set(cache_url, resp)
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# Add to the cache if the response headers demand it. If there
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# is no date header then we can't do anything about expiring
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# the cache.
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elif 'date' in resp.headers:
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# cache when there is a max-age > 0
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if cc and cc.get('max-age'):
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if int(cc['max-age']) > 0:
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self.cache.set(cache_url, resp)
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# If the request can expire, it means we should cache it
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# in the meantime.
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elif 'expires' in resp.headers:
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if resp.headers['expires']:
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self.cache.set(cache_url, resp)
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# If the request is for our local cache, it means we should cache it
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elif self.cache_force:
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resp.headers.update({'cache-control': 'max-age=21600, private'})
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self.cache.set(cache_url, resp)
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def update_cached_response(self, request, response):
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"""On a 304 we will get a new set of headers that we want to
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update our cached value with, assuming we have one.
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This should only ever be called when we've sent an ETag and
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gotten a 304 as the response.
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"""
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cache_url = self.cache_url(request.url)
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resp = self.cache.get(cache_url)
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if not resp:
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# we didn't have a cached response
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return response
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# did so lets update our headers
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resp.headers.update(resp.headers)
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# we want a 200 b/c we have content via the cache
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request.status_code = 200
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# update the request as it has the if-none-match header + any
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# other headers that the server might have updated (ie Date,
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# Cache-Control, Expires, etc.)
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resp.request = request
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# update our cache
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self.cache.set(cache_url, resp)
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# Let everyone know this was from the cache.
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resp.from_cache = True
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return resp
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