def send(self,
request,
stream=None,
timeout=None,
verify=None,
cert=None,
proxies=None):
pathname = url_to_path(request.url)
resp = Response()
resp.status_code = 200
resp.url = request.url
try:
stats = os.stat(pathname)
except OSError as exc:
resp.status_code = 404
resp.raw = exc
else:
modified = email.utils.formatdate(stats.st_mtime, usegmt=True)
content_type = mimetypes.guess_type(pathname)[0] or "text/plain"
resp.headers = CaseInsensitiveDict({
"Content-Type": content_type,
"Content-Length": stats.st_size,
"Last-Modified": modified,
})
resp.raw = open(pathname, "rb")
resp.close = resp.raw.close
return resp
def dumps(self, request, response, body=None):
response_headers = CaseInsensitiveDict(response.headers)
if body is None:
body = response.read(decode_content=False)
# NOTE: 99% sure this is dead code. I'm only leaving it
# here b/c I don't have a test yet to prove
# it. Basically, before using
# `cachecontrol.filewrapper.CallbackFileWrapper`,
# this made an effort to reset the file handle. The
# `CallbackFileWrapper` short circuits this code by
# setting the body as the content is consumed, the
# result being a `body` argument is *always* passed
# into cache_response, and in turn,
# `Serializer.dump`.
response._fp = io.BytesIO(body)
data = {
"response": {
"body":
_b64_encode_bytes(body),
"headers":
dict((_b64_encode(k), _b64_encode(v))
for k, v in response.headers.items()),
"status":
response.status,
"version":
response.version,
"reason":
_b64_encode_str(response.reason),
"strict":
response.strict,
"decode_content":
response.decode_content,
},
}
# Construct our vary headers
data["vary"] = {}
if "vary" in response_headers:
varied_headers = response_headers['vary'].split(',')
for header in varied_headers:
header = header.strip()
data["vary"][header] = request.headers.get(header, None)
# Encode our Vary headers to ensure they can be serialized as JSON
data["vary"] = dict(
(_b64_encode(k), _b64_encode(v) if v is not None else v)
for k, v in data["vary"].items())
return b",".join([
b"cc=2",
zlib.compress(
json.dumps(
data,
separators=(",", ":"),
sort_keys=True,
).encode("utf8"), ),
])
def prepare_response(self, request, cached):
"""Verify our vary headers match and construct a real urllib3
HTTPResponse object.
"""
# Special case the '*' Vary value as it means we cannot actually
# determine if the cached response is suitable for this request.
if "*" in cached.get("vary", {}):
return
# Ensure that the Vary headers for the cached response match our
# request
for header, value in cached.get("vary", {}).items():
if request.headers.get(header, None) != value:
return
body_raw = cached["response"].pop("body")
headers = CaseInsensitiveDict(data=cached['response']['headers'])
if headers.get('transfer-encoding', '') == 'chunked':
headers.pop('transfer-encoding')
cached['response']['headers'] = headers
try:
body = io.BytesIO(body_raw)
except TypeError:
# This can happen if cachecontrol serialized to v1 format (pickle)
# using Python 2. A Python 2 str(byte string) will be unpickled as
# a Python 3 str (unicode string), which will cause the above to
# fail with:
#
# TypeError: 'str' does not support the buffer interface
body = io.BytesIO(body_raw.encode('utf8'))
return HTTPResponse(body=body,
preload_content=False,
**cached["response"])
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 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 and resp_cc['max-age'].isdigit():
freshness_lifetime = int(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:
try:
freshness_lifetime = int(cc['max-age'])
logger.debug('Freshness lifetime from request max-age: %i',
freshness_lifetime)
except ValueError:
freshness_lifetime = 0
if 'min-fresh' in cc:
try:
min_fresh = int(cc['min-fresh'])
except ValueError:
min_fresh = 0
# 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 cache_response(self, request, response, body=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 = [200, 203, 300, 301]
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 cc.get('no-store'):
no_store = True
logger.debug('Response header has "no-store"')
if cc_req.get('no-store'):
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 cc and cc.get('max-age'):
if cc['max-age'].isdigit() and int(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),
)