189 lines
6.9 KiB
Python
189 lines
6.9 KiB
Python
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import base64
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import io
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import json
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import zlib
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from pip._vendor import msgpack
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from pip._vendor.requests.structures import CaseInsensitiveDict
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from .compat import HTTPResponse, pickle, text_type
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def _b64_decode_bytes(b):
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return base64.b64decode(b.encode("ascii"))
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def _b64_decode_str(s):
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return _b64_decode_bytes(s).decode("utf8")
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class Serializer(object):
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def dumps(self, request, response, body=None):
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response_headers = CaseInsensitiveDict(response.headers)
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if body is None:
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body = response.read(decode_content=False)
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# NOTE: 99% sure this is dead code. I'm only leaving it
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# here b/c I don't have a test yet to prove
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# it. Basically, before using
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# `cachecontrol.filewrapper.CallbackFileWrapper`,
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# this made an effort to reset the file handle. The
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# `CallbackFileWrapper` short circuits this code by
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# setting the body as the content is consumed, the
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# result being a `body` argument is *always* passed
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# into cache_response, and in turn,
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# `Serializer.dump`.
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response._fp = io.BytesIO(body)
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# NOTE: This is all a bit weird, but it's really important that on
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# Python 2.x these objects are unicode and not str, even when
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# they contain only ascii. The problem here is that msgpack
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# understands the difference between unicode and bytes and we
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# have it set to differentiate between them, however Python 2
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# doesn't know the difference. Forcing these to unicode will be
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# enough to have msgpack know the difference.
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data = {
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u"response": {
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u"body": body,
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u"headers": dict(
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(text_type(k), text_type(v)) for k, v in response.headers.items()
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),
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u"status": response.status,
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u"version": response.version,
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u"reason": text_type(response.reason),
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u"strict": response.strict,
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u"decode_content": response.decode_content,
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}
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}
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# Construct our vary headers
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data[u"vary"] = {}
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if u"vary" in response_headers:
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varied_headers = response_headers[u"vary"].split(",")
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for header in varied_headers:
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header = text_type(header).strip()
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header_value = request.headers.get(header, None)
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if header_value is not None:
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header_value = text_type(header_value)
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data[u"vary"][header] = header_value
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return b",".join([b"cc=4", msgpack.dumps(data, use_bin_type=True)])
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def loads(self, request, data):
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# Short circuit if we've been given an empty set of data
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if not data:
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return
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# Determine what version of the serializer the data was serialized
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# with
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try:
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ver, data = data.split(b",", 1)
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except ValueError:
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ver = b"cc=0"
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# Make sure that our "ver" is actually a version and isn't a false
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# positive from a , being in the data stream.
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if ver[:3] != b"cc=":
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data = ver + data
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ver = b"cc=0"
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# Get the version number out of the cc=N
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ver = ver.split(b"=", 1)[-1].decode("ascii")
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# Dispatch to the actual load method for the given version
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try:
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return getattr(self, "_loads_v{}".format(ver))(request, data)
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except AttributeError:
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# This is a version we don't have a loads function for, so we'll
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# just treat it as a miss and return None
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return
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def prepare_response(self, request, cached):
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"""Verify our vary headers match and construct a real urllib3
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HTTPResponse object.
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"""
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# Special case the '*' Vary value as it means we cannot actually
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# determine if the cached response is suitable for this request.
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# This case is also handled in the controller code when creating
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# a cache entry, but is left here for backwards compatibility.
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if "*" in cached.get("vary", {}):
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return
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# Ensure that the Vary headers for the cached response match our
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# request
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for header, value in cached.get("vary", {}).items():
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if request.headers.get(header, None) != value:
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return
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body_raw = cached["response"].pop("body")
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headers = CaseInsensitiveDict(data=cached["response"]["headers"])
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if headers.get("transfer-encoding", "") == "chunked":
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headers.pop("transfer-encoding")
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cached["response"]["headers"] = headers
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try:
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body = io.BytesIO(body_raw)
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except TypeError:
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# This can happen if cachecontrol serialized to v1 format (pickle)
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# using Python 2. A Python 2 str(byte string) will be unpickled as
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# a Python 3 str (unicode string), which will cause the above to
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# fail with:
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#
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# TypeError: 'str' does not support the buffer interface
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body = io.BytesIO(body_raw.encode("utf8"))
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return HTTPResponse(body=body, preload_content=False, **cached["response"])
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def _loads_v0(self, request, data):
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# The original legacy cache data. This doesn't contain enough
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# information to construct everything we need, so we'll treat this as
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# a miss.
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return
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def _loads_v1(self, request, data):
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try:
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cached = pickle.loads(data)
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except ValueError:
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return
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return self.prepare_response(request, cached)
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def _loads_v2(self, request, data):
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try:
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cached = json.loads(zlib.decompress(data).decode("utf8"))
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except (ValueError, zlib.error):
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return
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# We need to decode the items that we've base64 encoded
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cached["response"]["body"] = _b64_decode_bytes(cached["response"]["body"])
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cached["response"]["headers"] = dict(
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(_b64_decode_str(k), _b64_decode_str(v))
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for k, v in cached["response"]["headers"].items()
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)
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cached["response"]["reason"] = _b64_decode_str(cached["response"]["reason"])
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cached["vary"] = dict(
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(_b64_decode_str(k), _b64_decode_str(v) if v is not None else v)
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for k, v in cached["vary"].items()
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)
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return self.prepare_response(request, cached)
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def _loads_v3(self, request, data):
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# Due to Python 2 encoding issues, it's impossible to know for sure
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# exactly how to load v3 entries, thus we'll treat these as a miss so
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# that they get rewritten out as v4 entries.
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return
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def _loads_v4(self, request, data):
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try:
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cached = msgpack.loads(data, raw=False)
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except ValueError:
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return
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return self.prepare_response(request, cached)
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