440 lines
16 KiB
Python
440 lines
16 KiB
Python
|
# SPDX-FileCopyrightText: 2015 Eric Larson
|
||
|
|
#
|
||
|
|
# SPDX-License-Identifier: Apache-2.0
|
||
|
|
|
||
|
|
"""
|
||
|
|
The httplib2 algorithms ported for use with requests.
|
||
|
|
"""
|
||
|
|
import logging
|
||
|
|
import re
|
||
|
|
import calendar
|
||
|
|
import time
|
||
|
|
from email.utils import parsedate_tz
|
||
|
|
|
||
|
|
from pip._vendor.requests.structures import CaseInsensitiveDict
|
||
|
|
|
||
|
|
from .cache import DictCache, SeparateBodyBaseCache
|
||
|
|
from .serialize import Serializer
|
||
|
|
|
||
|
|
|
||
|
|
logger = logging.getLogger(__name__)
|
||
|
|
|
||
|
|
URI = re.compile(r"^(([^:/?#]+):)?(//([^/?#]*))?([^?#]*)(\?([^#]*))?(#(.*))?")
|
||
|
|
|
||
|
|
PERMANENT_REDIRECT_STATUSES = (301, 308)
|
||
|
|
|
||
|
|
|
||
|
|
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 = DictCache() if cache is None else cache
|
||
|
|
self.cache_etags = cache_etags
|
||
|
|
self.serializer = serializer or Serializer()
|
||
|
|
self.cacheable_status_codes = status_codes or (200, 203, 300, 301, 308)
|
||
|
|
|
||
|
|
@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(","):
|
||
|
|
if not cc_directive.strip():
|
||
|
|
continue
|
||
|
|
|
||
|
|
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
|
||
|
|
|
||
|
|
if isinstance(self.cache, SeparateBodyBaseCache):
|
||
|
|
body_file = self.cache.get_body(cache_url)
|
||
|
|
else:
|
||
|
|
body_file = None
|
||
|
|
|
||
|
|
# Check whether it can be deserialized
|
||
|
|
resp = self.serializer.loads(request, cache_data, body_file)
|
||
|
|
if not resp:
|
||
|
|
logger.warning("Cache entry deserialization failed, entry ignored")
|
||
|
|
return False
|
||
|
|
|
||
|
|
# If we have a cached permanent redirect, 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 int(resp.status) in PERMANENT_REDIRECT_STATUSES:
|
||
|
|
msg = (
|
||
|
|
"Returning cached permanent redirect 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_set(self, cache_url, request, response, body=None, expires_time=None):
|
||
|
|
"""
|
||
|
|
Store the data in the cache.
|
||
|
|
"""
|
||
|
|
if isinstance(self.cache, SeparateBodyBaseCache):
|
||
|
|
# We pass in the body separately; just put a placeholder empty
|
||
|
|
# string in the metadata.
|
||
|
|
self.cache.set(
|
||
|
|
cache_url,
|
||
|
|
self.serializer.dumps(request, response, b""),
|
||
|
|
expires=expires_time,
|
||
|
|
)
|
||
|
|
self.cache.set_body(cache_url, body)
|
||
|
|
else:
|
||
|
|
self.cache.set(
|
||
|
|
cache_url,
|
||
|
|
self.serializer.dumps(request, response, body),
|
||
|
|
expires=expires_time,
|
||
|
|
)
|
||
|
|
|
||
|
|
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 "date" in response_headers:
|
||
|
|
date = calendar.timegm(parsedate_tz(response_headers["date"]))
|
||
|
|
else:
|
||
|
|
date = 0
|
||
|
|
|
||
|
|
# 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 no_store:
|
||
|
|
return
|
||
|
|
|
||
|
|
# https://tools.ietf.org/html/rfc7234#section-4.1:
|
||
|
|
# A Vary header field-value of "*" always fails to match.
|
||
|
|
# Storing such a response leads to a deserialization warning
|
||
|
|
# during cache lookup and is not allowed to ever be served,
|
||
|
|
# so storing it can be avoided.
|
||
|
|
if "*" in response_headers.get("vary", ""):
|
||
|
|
logger.debug('Response header has "Vary: *"')
|
||
|
|
return
|
||
|
|
|
||
|
|
# If we've been given an etag, then keep the response
|
||
|
|
if self.cache_etags and "etag" in response_headers:
|
||
|
|
expires_time = 0
|
||
|
|
if response_headers.get("expires"):
|
||
|
|
expires = parsedate_tz(response_headers["expires"])
|
||
|
|
if expires is not None:
|
||
|
|
expires_time = calendar.timegm(expires) - date
|
||
|
|
|
||
|
|
expires_time = max(expires_time, 14 * 86400)
|
||
|
|
|
||
|
|
logger.debug("etag object cached for {0} seconds".format(expires_time))
|
||
|
|
logger.debug("Caching due to etag")
|
||
|
|
self._cache_set(cache_url, request, response, body, expires_time)
|
||
|
|
|
||
|
|
# Add to the cache any permanent redirects. We do this before looking
|
||
|
|
# that the Date headers.
|
||
|
|
elif int(response.status) in PERMANENT_REDIRECT_STATUSES:
|
||
|
|
logger.debug("Caching permanent redirect")
|
||
|
|
self._cache_set(cache_url, request, response, b"")
|
||
|
|
|
||
|
|
# 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:
|
||
|
|
date = calendar.timegm(parsedate_tz(response_headers["date"]))
|
||
|
|
# 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")
|
||
|
|
expires_time = cc["max-age"]
|
||
|
|
self._cache_set(
|
||
|
|
cache_url,
|
||
|
|
request,
|
||
|
|
response,
|
||
|
|
body,
|
||
|
|
expires_time,
|
||
|
|
)
|
||
|
|
|
||
|
|
# If the request can expire, it means we should cache it
|
||
|
|
# in the meantime.
|
||
|
|
elif "expires" in response_headers:
|
||
|
|
if response_headers["expires"]:
|
||
|
|
expires = parsedate_tz(response_headers["expires"])
|
||
|
|
if expires is not None:
|
||
|
|
expires_time = calendar.timegm(expires) - date
|
||
|
|
else:
|
||
|
|
expires_time = None
|
||
|
|
|
||
|
|
logger.debug(
|
||
|
|
"Caching b/c of expires header. expires in {0} seconds".format(
|
||
|
|
expires_time
|
||
|
|
)
|
||
|
|
)
|
||
|
|
self._cache_set(
|
||
|
|
cache_url,
|
||
|
|
request,
|
||
|
|
response,
|
||
|
|
body,
|
||
|
|
expires_time,
|
||
|
|
)
|
||
|
|
|
||
|
|
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, request, cached_response)
|
||
|
|
|
||
|
|
return cached_response
|