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import base64
import io
import json
import zlib
from pip._vendor import msgpack
from pip._vendor.requests.structures import CaseInsensitiveDict
from .compat import HTTPResponse, pickle, text_type
def _b64_decode_bytes(b):
return base64.b64decode(b.encode("ascii"))
def _b64_decode_str(s):
return _b64_decode_bytes(s).decode("utf8")
class Serializer(object):
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)
# NOTE: This is all a bit weird, but it's really important that on
# Python 2.x these objects are unicode and not str, even when
# they contain only ascii. The problem here is that msgpack
# understands the difference between unicode and bytes and we
# have it set to differentiate between them, however Python 2
# doesn't know the difference. Forcing these to unicode will be
# enough to have msgpack know the difference.
data = {
u"response": {
u"body": body,
u"headers": dict(
(text_type(k), text_type(v)) for k, v in response.headers.items()
),
u"status": response.status,
u"version": response.version,
u"reason": text_type(response.reason),
u"strict": response.strict,
u"decode_content": response.decode_content,
}
}
# Construct our vary headers
data[u"vary"] = {}
if u"vary" in response_headers:
varied_headers = response_headers[u"vary"].split(",")
for header in varied_headers:
header = text_type(header).strip()
header_value = request.headers.get(header, None)
if header_value is not None:
header_value = text_type(header_value)
data[u"vary"][header] = header_value
return b",".join([b"cc=4", msgpack.dumps(data, use_bin_type=True)])
def loads(self, request, data):
# Short circuit if we've been given an empty set of data
if not data:
return
# Determine what version of the serializer the data was serialized
# with
try:
ver, data = data.split(b",", 1)
except ValueError:
ver = b"cc=0"
# Make sure that our "ver" is actually a version and isn't a false
# positive from a , being in the data stream.
if ver[:3] != b"cc=":
data = ver + data
ver = b"cc=0"
# Get the version number out of the cc=N
ver = ver.split(b"=", 1)[-1].decode("ascii")
# Dispatch to the actual load method for the given version
try:
return getattr(self, "_loads_v{}".format(ver))(request, data)
except AttributeError:
# This is a version we don't have a loads function for, so we'll
# just treat it as a miss and return None
return
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 _loads_v0(self, request, data):
# The original legacy cache data. This doesn't contain enough
# information to construct everything we need, so we'll treat this as
# a miss.
return
def _loads_v1(self, request, data):
try:
cached = pickle.loads(data)
except ValueError:
return
return self.prepare_response(request, cached)
def _loads_v2(self, request, data):
try:
cached = json.loads(zlib.decompress(data).decode("utf8"))
except (ValueError, zlib.error):
return
# We need to decode the items that we've base64 encoded
cached["response"]["body"] = _b64_decode_bytes(cached["response"]["body"])
cached["response"]["headers"] = dict(
(_b64_decode_str(k), _b64_decode_str(v))
for k, v in cached["response"]["headers"].items()
)
cached["response"]["reason"] = _b64_decode_str(cached["response"]["reason"])
cached["vary"] = dict(
(_b64_decode_str(k), _b64_decode_str(v) if v is not None else v)
for k, v in cached["vary"].items()
)
return self.prepare_response(request, cached)
def _loads_v3(self, request, data):
# Due to Python 2 encoding issues, it's impossible to know for sure
# exactly how to load v3 entries, thus we'll treat these as a miss so
# that they get rewritten out as v4 entries.
return
def _loads_v4(self, request, data):
try:
cached = msgpack.loads(data, encoding="utf-8")
except ValueError:
return
return self.prepare_response(request, cached)