649 lines
21 KiB
Python
649 lines
21 KiB
Python
# urllib3/util.py
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# Copyright 2008-2013 Andrey Petrov and contributors (see CONTRIBUTORS.txt)
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#
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# This module is part of urllib3 and is released under
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# the MIT License: http://www.opensource.org/licenses/mit-license.php
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from base64 import b64encode
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from binascii import hexlify, unhexlify
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from collections import namedtuple
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from hashlib import md5, sha1
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from socket import error as SocketError, _GLOBAL_DEFAULT_TIMEOUT
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import time
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try:
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from select import poll, POLLIN
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except ImportError: # `poll` doesn't exist on OSX and other platforms
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poll = False
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try:
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from select import select
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except ImportError: # `select` doesn't exist on AppEngine.
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select = False
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try: # Test for SSL features
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SSLContext = None
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HAS_SNI = False
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import ssl
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from ssl import wrap_socket, CERT_NONE, PROTOCOL_SSLv23
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from ssl import SSLContext # Modern SSL?
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from ssl import HAS_SNI # Has SNI?
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except ImportError:
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pass
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from .packages import six
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from .exceptions import LocationParseError, SSLError, TimeoutStateError
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_Default = object()
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# The default timeout to use for socket connections. This is the attribute used
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# by httplib to define the default timeout
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def current_time():
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"""
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Retrieve the current time, this function is mocked out in unit testing.
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"""
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return time.time()
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class Timeout(object):
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"""
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Utility object for storing timeout values.
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Example usage:
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.. code-block:: python
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timeout = urllib3.util.Timeout(connect=2.0, read=7.0)
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pool = HTTPConnectionPool('www.google.com', 80, timeout=timeout)
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pool.request(...) # Etc, etc
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:param connect:
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The maximum amount of time to wait for a connection attempt to a server
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to succeed. Omitting the parameter will default the connect timeout to
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the system default, probably `the global default timeout in socket.py
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<http://hg.python.org/cpython/file/603b4d593758/Lib/socket.py#l535>`_.
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None will set an infinite timeout for connection attempts.
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:type connect: integer, float, or None
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:param read:
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The maximum amount of time to wait between consecutive
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read operations for a response from the server. Omitting
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the parameter will default the read timeout to the system
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default, probably `the global default timeout in socket.py
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<http://hg.python.org/cpython/file/603b4d593758/Lib/socket.py#l535>`_.
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None will set an infinite timeout.
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:type read: integer, float, or None
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:param total:
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This combines the connect and read timeouts into one; the read timeout
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will be set to the time leftover from the connect attempt. In the
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event that both a connect timeout and a total are specified, or a read
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timeout and a total are specified, the shorter timeout will be applied.
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Defaults to None.
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:type total: integer, float, or None
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.. note::
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Many factors can affect the total amount of time for urllib3 to return
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an HTTP response. Specifically, Python's DNS resolver does not obey the
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timeout specified on the socket. Other factors that can affect total
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request time include high CPU load, high swap, the program running at a
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low priority level, or other behaviors. The observed running time for
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urllib3 to return a response may be greater than the value passed to
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`total`.
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In addition, the read and total timeouts only measure the time between
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read operations on the socket connecting the client and the server,
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not the total amount of time for the request to return a complete
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response. For most requests, the timeout is raised because the server
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has not sent the first byte in the specified time. This is not always
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the case; if a server streams one byte every fifteen seconds, a timeout
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of 20 seconds will not ever trigger, even though the request will
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take several minutes to complete.
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If your goal is to cut off any request after a set amount of wall clock
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time, consider having a second "watcher" thread to cut off a slow
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request.
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"""
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#: A sentinel object representing the default timeout value
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DEFAULT_TIMEOUT = _GLOBAL_DEFAULT_TIMEOUT
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def __init__(self, total=None, connect=_Default, read=_Default):
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self._connect = self._validate_timeout(connect, 'connect')
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self._read = self._validate_timeout(read, 'read')
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self.total = self._validate_timeout(total, 'total')
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self._start_connect = None
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def __str__(self):
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return '%s(connect=%r, read=%r, total=%r)' % (
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type(self).__name__, self._connect, self._read, self.total)
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@classmethod
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def _validate_timeout(cls, value, name):
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""" Check that a timeout attribute is valid
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:param value: The timeout value to validate
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:param name: The name of the timeout attribute to validate. This is used
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for clear error messages
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:return: the value
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:raises ValueError: if the type is not an integer or a float, or if it
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is a numeric value less than zero
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"""
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if value is _Default:
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return cls.DEFAULT_TIMEOUT
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if value is None or value is cls.DEFAULT_TIMEOUT:
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return value
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try:
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float(value)
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except (TypeError, ValueError):
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raise ValueError("Timeout value %s was %s, but it must be an "
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"int or float." % (name, value))
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try:
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if value < 0:
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raise ValueError("Attempted to set %s timeout to %s, but the "
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"timeout cannot be set to a value less "
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"than 0." % (name, value))
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except TypeError: # Python 3
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raise ValueError("Timeout value %s was %s, but it must be an "
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"int or float." % (name, value))
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return value
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@classmethod
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def from_float(cls, timeout):
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""" Create a new Timeout from a legacy timeout value.
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The timeout value used by httplib.py sets the same timeout on the
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connect(), and recv() socket requests. This creates a :class:`Timeout`
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object that sets the individual timeouts to the ``timeout`` value passed
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to this function.
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:param timeout: The legacy timeout value
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:type timeout: integer, float, sentinel default object, or None
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:return: a Timeout object
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:rtype: :class:`Timeout`
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"""
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return Timeout(read=timeout, connect=timeout)
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def clone(self):
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""" Create a copy of the timeout object
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Timeout properties are stored per-pool but each request needs a fresh
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Timeout object to ensure each one has its own start/stop configured.
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:return: a copy of the timeout object
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:rtype: :class:`Timeout`
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"""
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# We can't use copy.deepcopy because that will also create a new object
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# for _GLOBAL_DEFAULT_TIMEOUT, which socket.py uses as a sentinel to
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# detect the user default.
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return Timeout(connect=self._connect, read=self._read,
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total=self.total)
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def start_connect(self):
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""" Start the timeout clock, used during a connect() attempt
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:raises urllib3.exceptions.TimeoutStateError: if you attempt
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to start a timer that has been started already.
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"""
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if self._start_connect is not None:
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raise TimeoutStateError("Timeout timer has already been started.")
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self._start_connect = current_time()
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return self._start_connect
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def get_connect_duration(self):
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""" Gets the time elapsed since the call to :meth:`start_connect`.
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:return: the elapsed time
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:rtype: float
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:raises urllib3.exceptions.TimeoutStateError: if you attempt
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to get duration for a timer that hasn't been started.
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"""
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if self._start_connect is None:
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raise TimeoutStateError("Can't get connect duration for timer "
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"that has not started.")
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return current_time() - self._start_connect
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@property
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def connect_timeout(self):
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""" Get the value to use when setting a connection timeout.
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This will be a positive float or integer, the value None
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(never timeout), or the default system timeout.
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:return: the connect timeout
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:rtype: int, float, :attr:`Timeout.DEFAULT_TIMEOUT` or None
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"""
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if self.total is None:
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return self._connect
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if self._connect is None or self._connect is self.DEFAULT_TIMEOUT:
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return self.total
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return min(self._connect, self.total)
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@property
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def read_timeout(self):
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""" Get the value for the read timeout.
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This assumes some time has elapsed in the connection timeout and
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computes the read timeout appropriately.
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If self.total is set, the read timeout is dependent on the amount of
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time taken by the connect timeout. If the connection time has not been
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established, a :exc:`~urllib3.exceptions.TimeoutStateError` will be
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raised.
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:return: the value to use for the read timeout
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:rtype: int, float, :attr:`Timeout.DEFAULT_TIMEOUT` or None
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:raises urllib3.exceptions.TimeoutStateError: If :meth:`start_connect`
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has not yet been called on this object.
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"""
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if (self.total is not None and
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self.total is not self.DEFAULT_TIMEOUT and
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self._read is not None and
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self._read is not self.DEFAULT_TIMEOUT):
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# in case the connect timeout has not yet been established.
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if self._start_connect is None:
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return self._read
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return max(0, min(self.total - self.get_connect_duration(),
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self._read))
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elif self.total is not None and self.total is not self.DEFAULT_TIMEOUT:
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return max(0, self.total - self.get_connect_duration())
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else:
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return self._read
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class Url(namedtuple('Url', ['scheme', 'auth', 'host', 'port', 'path', 'query', 'fragment'])):
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"""
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Datastructure for representing an HTTP URL. Used as a return value for
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:func:`parse_url`.
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"""
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slots = ()
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def __new__(cls, scheme=None, auth=None, host=None, port=None, path=None, query=None, fragment=None):
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return super(Url, cls).__new__(cls, scheme, auth, host, port, path, query, fragment)
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@property
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def hostname(self):
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"""For backwards-compatibility with urlparse. We're nice like that."""
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return self.host
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@property
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def request_uri(self):
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"""Absolute path including the query string."""
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uri = self.path or '/'
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if self.query is not None:
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uri += '?' + self.query
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return uri
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@property
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def netloc(self):
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"""Network location including host and port"""
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if self.port:
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return '%s:%d' % (self.host, self.port)
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return self.host
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def split_first(s, delims):
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"""
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Given a string and an iterable of delimiters, split on the first found
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delimiter. Return two split parts and the matched delimiter.
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If not found, then the first part is the full input string.
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Example: ::
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>>> split_first('foo/bar?baz', '?/=')
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('foo', 'bar?baz', '/')
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>>> split_first('foo/bar?baz', '123')
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('foo/bar?baz', '', None)
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Scales linearly with number of delims. Not ideal for large number of delims.
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"""
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min_idx = None
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min_delim = None
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for d in delims:
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idx = s.find(d)
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if idx < 0:
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continue
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if min_idx is None or idx < min_idx:
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min_idx = idx
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min_delim = d
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if min_idx is None or min_idx < 0:
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return s, '', None
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return s[:min_idx], s[min_idx+1:], min_delim
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def parse_url(url):
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"""
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Given a url, return a parsed :class:`.Url` namedtuple. Best-effort is
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performed to parse incomplete urls. Fields not provided will be None.
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Partly backwards-compatible with :mod:`urlparse`.
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Example: ::
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>>> parse_url('http://google.com/mail/')
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Url(scheme='http', host='google.com', port=None, path='/', ...)
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>>> parse_url('google.com:80')
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Url(scheme=None, host='google.com', port=80, path=None, ...)
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>>> parse_url('/foo?bar')
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Url(scheme=None, host=None, port=None, path='/foo', query='bar', ...)
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"""
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# While this code has overlap with stdlib's urlparse, it is much
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# simplified for our needs and less annoying.
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# Additionally, this implementations does silly things to be optimal
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# on CPython.
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scheme = None
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auth = None
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host = None
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port = None
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path = None
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fragment = None
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query = None
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# Scheme
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if '://' in url:
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scheme, url = url.split('://', 1)
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# Find the earliest Authority Terminator
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# (http://tools.ietf.org/html/rfc3986#section-3.2)
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url, path_, delim = split_first(url, ['/', '?', '#'])
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if delim:
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# Reassemble the path
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path = delim + path_
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# Auth
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if '@' in url:
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# Last '@' denotes end of auth part
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auth, url = url.rsplit('@', 1)
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# IPv6
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if url and url[0] == '[':
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host, url = url.split(']', 1)
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host += ']'
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# Port
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if ':' in url:
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_host, port = url.split(':', 1)
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if not host:
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host = _host
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if port:
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# If given, ports must be integers.
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if not port.isdigit():
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raise LocationParseError("Failed to parse: %s" % url)
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port = int(port)
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else:
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# Blank ports are cool, too. (rfc3986#section-3.2.3)
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port = None
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elif not host and url:
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host = url
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if not path:
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return Url(scheme, auth, host, port, path, query, fragment)
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# Fragment
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if '#' in path:
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path, fragment = path.split('#', 1)
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# Query
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if '?' in path:
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path, query = path.split('?', 1)
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return Url(scheme, auth, host, port, path, query, fragment)
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def get_host(url):
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"""
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Deprecated. Use :func:`.parse_url` instead.
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"""
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p = parse_url(url)
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return p.scheme or 'http', p.hostname, p.port
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def make_headers(keep_alive=None, accept_encoding=None, user_agent=None,
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basic_auth=None, proxy_basic_auth=None):
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"""
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Shortcuts for generating request headers.
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:param keep_alive:
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If ``True``, adds 'connection: keep-alive' header.
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:param accept_encoding:
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Can be a boolean, list, or string.
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``True`` translates to 'gzip,deflate'.
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List will get joined by comma.
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String will be used as provided.
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:param user_agent:
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String representing the user-agent you want, such as
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"python-urllib3/0.6"
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:param basic_auth:
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Colon-separated username:password string for 'authorization: basic ...'
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auth header.
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:param proxy_basic_auth:
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Colon-separated username:password string for 'proxy-authorization: basic ...'
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auth header.
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Example: ::
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>>> make_headers(keep_alive=True, user_agent="Batman/1.0")
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{'connection': 'keep-alive', 'user-agent': 'Batman/1.0'}
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>>> make_headers(accept_encoding=True)
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{'accept-encoding': 'gzip,deflate'}
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"""
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headers = {}
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if accept_encoding:
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if isinstance(accept_encoding, str):
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pass
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elif isinstance(accept_encoding, list):
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accept_encoding = ','.join(accept_encoding)
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else:
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accept_encoding = 'gzip,deflate'
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headers['accept-encoding'] = accept_encoding
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if user_agent:
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headers['user-agent'] = user_agent
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if keep_alive:
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headers['connection'] = 'keep-alive'
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if basic_auth:
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headers['authorization'] = 'Basic ' + \
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b64encode(six.b(basic_auth)).decode('utf-8')
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if proxy_basic_auth:
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headers['proxy-authorization'] = 'Basic ' + \
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b64encode(six.b(proxy_basic_auth)).decode('utf-8')
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return headers
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def is_connection_dropped(conn): # Platform-specific
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"""
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Returns True if the connection is dropped and should be closed.
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:param conn:
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:class:`httplib.HTTPConnection` object.
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Note: For platforms like AppEngine, this will always return ``False`` to
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let the platform handle connection recycling transparently for us.
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"""
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sock = getattr(conn, 'sock', False)
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if not sock: # Platform-specific: AppEngine
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return False
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if not poll:
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if not select: # Platform-specific: AppEngine
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return False
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try:
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return select([sock], [], [], 0.0)[0]
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except SocketError:
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return True
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# This version is better on platforms that support it.
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p = poll()
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p.register(sock, POLLIN)
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for (fno, ev) in p.poll(0.0):
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if fno == sock.fileno():
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# Either data is buffered (bad), or the connection is dropped.
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return True
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def resolve_cert_reqs(candidate):
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"""
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Resolves the argument to a numeric constant, which can be passed to
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the wrap_socket function/method from the ssl module.
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Defaults to :data:`ssl.CERT_NONE`.
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If given a string it is assumed to be the name of the constant in the
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:mod:`ssl` module or its abbrevation.
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(So you can specify `REQUIRED` instead of `CERT_REQUIRED`.
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If it's neither `None` nor a string we assume it is already the numeric
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constant which can directly be passed to wrap_socket.
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"""
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if candidate is None:
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return CERT_NONE
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if isinstance(candidate, str):
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res = getattr(ssl, candidate, None)
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if res is None:
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res = getattr(ssl, 'CERT_' + candidate)
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return res
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return candidate
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def resolve_ssl_version(candidate):
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"""
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like resolve_cert_reqs
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"""
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if candidate is None:
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return PROTOCOL_SSLv23
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|
if isinstance(candidate, str):
|
|
res = getattr(ssl, candidate, None)
|
|
if res is None:
|
|
res = getattr(ssl, 'PROTOCOL_' + candidate)
|
|
return res
|
|
|
|
return candidate
|
|
|
|
|
|
def assert_fingerprint(cert, fingerprint):
|
|
"""
|
|
Checks if given fingerprint matches the supplied certificate.
|
|
|
|
:param cert:
|
|
Certificate as bytes object.
|
|
:param fingerprint:
|
|
Fingerprint as string of hexdigits, can be interspersed by colons.
|
|
"""
|
|
|
|
# Maps the length of a digest to a possible hash function producing
|
|
# this digest.
|
|
hashfunc_map = {
|
|
16: md5,
|
|
20: sha1
|
|
}
|
|
|
|
fingerprint = fingerprint.replace(':', '').lower()
|
|
|
|
digest_length, rest = divmod(len(fingerprint), 2)
|
|
|
|
if rest or digest_length not in hashfunc_map:
|
|
raise SSLError('Fingerprint is of invalid length.')
|
|
|
|
# We need encode() here for py32; works on py2 and p33.
|
|
fingerprint_bytes = unhexlify(fingerprint.encode())
|
|
|
|
hashfunc = hashfunc_map[digest_length]
|
|
|
|
cert_digest = hashfunc(cert).digest()
|
|
|
|
if not cert_digest == fingerprint_bytes:
|
|
raise SSLError('Fingerprints did not match. Expected "{0}", got "{1}".'
|
|
.format(hexlify(fingerprint_bytes),
|
|
hexlify(cert_digest)))
|
|
|
|
def is_fp_closed(obj):
|
|
"""
|
|
Checks whether a given file-like object is closed.
|
|
|
|
:param obj:
|
|
The file-like object to check.
|
|
"""
|
|
if hasattr(obj, 'fp'):
|
|
# Object is a container for another file-like object that gets released
|
|
# on exhaustion (e.g. HTTPResponse)
|
|
return obj.fp is None
|
|
|
|
return obj.closed
|
|
|
|
|
|
if SSLContext is not None: # Python 3.2+
|
|
def ssl_wrap_socket(sock, keyfile=None, certfile=None, cert_reqs=None,
|
|
ca_certs=None, server_hostname=None,
|
|
ssl_version=None):
|
|
"""
|
|
All arguments except `server_hostname` have the same meaning as for
|
|
:func:`ssl.wrap_socket`
|
|
|
|
:param server_hostname:
|
|
Hostname of the expected certificate
|
|
"""
|
|
context = SSLContext(ssl_version)
|
|
context.verify_mode = cert_reqs
|
|
|
|
# Disable TLS compression to migitate CRIME attack (issue #309)
|
|
OP_NO_COMPRESSION = 0x20000
|
|
context.options |= OP_NO_COMPRESSION
|
|
|
|
if ca_certs:
|
|
try:
|
|
context.load_verify_locations(ca_certs)
|
|
# Py32 raises IOError
|
|
# Py33 raises FileNotFoundError
|
|
except Exception as e: # Reraise as SSLError
|
|
raise SSLError(e)
|
|
if certfile:
|
|
# FIXME: This block needs a test.
|
|
context.load_cert_chain(certfile, keyfile)
|
|
if HAS_SNI: # Platform-specific: OpenSSL with enabled SNI
|
|
return context.wrap_socket(sock, server_hostname=server_hostname)
|
|
return context.wrap_socket(sock)
|
|
|
|
else: # Python 3.1 and earlier
|
|
def ssl_wrap_socket(sock, keyfile=None, certfile=None, cert_reqs=None,
|
|
ca_certs=None, server_hostname=None,
|
|
ssl_version=None):
|
|
return wrap_socket(sock, keyfile=keyfile, certfile=certfile,
|
|
ca_certs=ca_certs, cert_reqs=cert_reqs,
|
|
ssl_version=ssl_version)
|