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Diffstat (limited to '.venv/lib/python3.12/site-packages/pip/_vendor/cachecontrol/controller.py')
| -rw-r--r-- | .venv/lib/python3.12/site-packages/pip/_vendor/cachecontrol/controller.py | 500 |
1 files changed, 500 insertions, 0 deletions
diff --git a/.venv/lib/python3.12/site-packages/pip/_vendor/cachecontrol/controller.py b/.venv/lib/python3.12/site-packages/pip/_vendor/cachecontrol/controller.py new file mode 100644 index 00000000..f0ff6e1b --- /dev/null +++ b/.venv/lib/python3.12/site-packages/pip/_vendor/cachecontrol/controller.py @@ -0,0 +1,500 @@ +# SPDX-FileCopyrightText: 2015 Eric Larson +# +# SPDX-License-Identifier: Apache-2.0 + +""" +The httplib2 algorithms ported for use with requests. +""" + +from __future__ import annotations + +import calendar +import logging +import re +import time +from email.utils import parsedate_tz +from typing import TYPE_CHECKING, Collection, Mapping + +from pip._vendor.requests.structures import CaseInsensitiveDict + +from pip._vendor.cachecontrol.cache import DictCache, SeparateBodyBaseCache +from pip._vendor.cachecontrol.serialize import Serializer + +if TYPE_CHECKING: + from typing import Literal + + from pip._vendor.requests import PreparedRequest + from pip._vendor.urllib3 import HTTPResponse + + from pip._vendor.cachecontrol.cache import BaseCache + +logger = logging.getLogger(__name__) + +URI = re.compile(r"^(([^:/?#]+):)?(//([^/?#]*))?([^?#]*)(\?([^#]*))?(#(.*))?") + +PERMANENT_REDIRECT_STATUSES = (301, 308) + + +def parse_uri(uri: str) -> tuple[str, str, str, str, str]: + """Parses a URI using the regex given in Appendix B of RFC 3986. + + (scheme, authority, path, query, fragment) = parse_uri(uri) + """ + match = URI.match(uri) + assert match is not None + groups = match.groups() + return (groups[1], groups[3], groups[4], groups[6], groups[8]) + + +class CacheController: + """An interface to see if request should cached or not.""" + + def __init__( + self, + cache: BaseCache | None = None, + cache_etags: bool = True, + serializer: Serializer | None = None, + status_codes: Collection[int] | None = 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: str) -> str: + """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: str) -> str: + return cls._urlnorm(uri) + + def parse_cache_control(self, headers: Mapping[str, str]) -> dict[str, int | None]: + 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: dict[str, int | None] = {} + + 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 _load_from_cache(self, request: PreparedRequest) -> HTTPResponse | None: + """ + Load a cached response, or return None if it's not available. + """ + # We do not support caching of partial content: so if the request contains a + # Range header then we don't want to load anything from the cache. + if "Range" in request.headers: + return None + + cache_url = request.url + assert cache_url is not None + cache_data = self.cache.get(cache_url) + if cache_data is None: + logger.debug("No cache entry available") + return None + + if isinstance(self.cache, SeparateBodyBaseCache): + body_file = self.cache.get_body(cache_url) + else: + body_file = None + + result = self.serializer.loads(request, cache_data, body_file) + if result is None: + logger.warning("Cache entry deserialization failed, entry ignored") + return result + + def cached_request(self, request: PreparedRequest) -> HTTPResponse | Literal[False]: + """ + Return a cached response if it exists in the cache, otherwise + return False. + """ + assert request.url is not None + 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 + + # Check whether we can load the response from the cache: + resp = self._load_from_cache(request) + if not resp: + 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[str] = 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() + time_tuple = parsedate_tz(headers["date"]) + assert time_tuple is not None + date = calendar.timegm(time_tuple[:6]) + 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 + max_age = resp_cc.get("max-age") + if max_age is not None: + freshness_lifetime = 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[:6]) - 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. + max_age = cc.get("max-age") + if max_age is not None: + freshness_lifetime = max_age + logger.debug( + "Freshness lifetime from request max-age: %i", freshness_lifetime + ) + + min_fresh = cc.get("min-fresh") + if min_fresh is not None: + # 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: PreparedRequest) -> dict[str, str]: + resp = self._load_from_cache(request) + new_headers = {} + + if resp: + headers: CaseInsensitiveDict[str] = 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: str, + request: PreparedRequest, + response: HTTPResponse, + body: bytes | None = None, + expires_time: int | None = None, + ) -> 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, + ) + # body is None can happen when, for example, we're only updating + # headers, as is the case in update_cached_response(). + if body is not None: + 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: PreparedRequest, + response: HTTPResponse, + body: bytes | None = None, + status_codes: Collection[int] | None = None, + ) -> 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[str] = CaseInsensitiveDict( + response.headers + ) + + if "date" in response_headers: + time_tuple = parsedate_tz(response_headers["date"]) + assert time_tuple is not None + date = calendar.timegm(time_tuple[:6]) + 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) + + assert request.url is not None + 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[:6]) - date + + expires_time = max(expires_time, 14 * 86400) + + logger.debug(f"etag object cached for {expires_time} seconds") + 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: + time_tuple = parsedate_tz(response_headers["date"]) + assert time_tuple is not None + date = calendar.timegm(time_tuple[:6]) + # cache when there is a max-age > 0 + max_age = cc.get("max-age") + if max_age is not None and max_age > 0: + logger.debug("Caching b/c date exists and max-age > 0") + expires_time = 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[:6]) - date + else: + expires_time = None + + logger.debug( + "Caching b/c of expires header. expires in {} seconds".format( + expires_time + ) + ) + self._cache_set( + cache_url, + request, + response, + body, + expires_time, + ) + + def update_cached_response( + self, request: PreparedRequest, response: HTTPResponse + ) -> HTTPResponse: + """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. + """ + assert request.url is not None + cache_url = self.cache_url(request.url) + cached_response = self._load_from_cache(request) + + 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( + { + 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 |