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from __future__ import absolute_import
from base64 import b64encode
from ..exceptions import UnrewindableBodyError
from ..packages.six import b, integer_types
# Pass as a value within ``headers`` to skip
# emitting some HTTP headers that are added automatically.
# The only headers that are supported are ``Accept-Encoding``,
# ``Host``, and ``User-Agent``.
SKIP_HEADER = "@@@SKIP_HEADER@@@"
SKIPPABLE_HEADERS = frozenset(["accept-encoding", "host", "user-agent"])
ACCEPT_ENCODING = "gzip,deflate"
_FAILEDTELL = object()
def make_headers(
keep_alive=None,
accept_encoding=None,
user_agent=None,
basic_auth=None,
proxy_basic_auth=None,
disable_cache=None,
):
"""
Shortcuts for generating request headers.
:param keep_alive:
If ``True``, adds 'connection: keep-alive' header.
:param accept_encoding:
Can be a boolean, list, or string.
``True`` translates to 'gzip,deflate'.
List will get joined by comma.
String will be used as provided.
:param user_agent:
String representing the user-agent you want, such as
"python-urllib3/0.6"
:param basic_auth:
Colon-separated username:password string for 'authorization: basic ...'
auth header.
:param proxy_basic_auth:
Colon-separated username:password string for 'proxy-authorization: basic ...'
auth header.
:param disable_cache:
If ``True``, adds 'cache-control: no-cache' header.
Example::
>>> make_headers(keep_alive=True, user_agent="Batman/1.0")
{'connection': 'keep-alive', 'user-agent': 'Batman/1.0'}
>>> make_headers(accept_encoding=True)
{'accept-encoding': 'gzip,deflate'}
"""
headers = {}
if accept_encoding:
if isinstance(accept_encoding, str):
pass
elif isinstance(accept_encoding, list):
accept_encoding = ",".join(accept_encoding)
else:
accept_encoding = ACCEPT_ENCODING
headers["accept-encoding"] = accept_encoding
if user_agent:
headers["user-agent"] = user_agent
if keep_alive:
headers["connection"] = "keep-alive"
if basic_auth:
headers["authorization"] = "Basic " + b64encode(b(basic_auth)).decode("utf-8")
if proxy_basic_auth:
headers["proxy-authorization"] = "Basic " + b64encode(
b(proxy_basic_auth)
).decode("utf-8")
if disable_cache:
headers["cache-control"] = "no-cache"
return headers
def set_file_position(body, pos):
"""
If a position is provided, move file to that point.
Otherwise, we'll attempt to record a position for future use.
"""
if pos is not None:
rewind_body(body, pos)
elif getattr(body, "tell", None) is not None:
try:
pos = body.tell()
except (IOError, OSError):
# This differentiates from None, allowing us to catch
# a failed `tell()` later when trying to rewind the body.
pos = _FAILEDTELL
return pos
def rewind_body(body, body_pos):
"""
Attempt to rewind body to a certain position.
Primarily used for request redirects and retries.
:param body:
File-like object that supports seek.
:param int pos:
Position to seek to in file.
"""
body_seek = getattr(body, "seek", None)
if body_seek is not None and isinstance(body_pos, integer_types):
try:
body_seek(body_pos)
except (IOError, OSError):
raise UnrewindableBodyError(
"An error occurred when rewinding request body for redirect/retry."
)
elif body_pos is _FAILEDTELL:
raise UnrewindableBodyError(
"Unable to record file position for rewinding "
"request body during a redirect/retry."
)
else:
raise ValueError(
"body_pos must be of type integer, instead it was %s." % type(body_pos)
)
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