308 lines
13 KiB
Python
308 lines
13 KiB
Python
# Copyright (c) 2012-2013 Mitch Garnaat http://garnaat.org/
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# Copyright 2012-2014 Amazon.com, Inc. or its affiliates. All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License"). You
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# may not use this file except in compliance with the License. A copy of
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# the License is located at
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#
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# http://aws.amazon.com/apache2.0/
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#
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# or in the "license" file accompanying this file. This file is
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# distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF
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# ANY KIND, either express or implied. See the License for the specific
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# language governing permissions and limitations under the License.
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import sys
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import logging
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import select
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import functools
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import socket
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import inspect
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import six
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from botocore.vendored.requests import models
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from botocore.vendored.requests.sessions import REDIRECT_STATI
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from botocore.compat import HTTPHeaders, HTTPResponse
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from botocore.exceptions import UnseekableStreamError
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from botocore.vendored.requests.packages.urllib3.connection import VerifiedHTTPSConnection
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from botocore.vendored.requests.packages.urllib3.connection import HTTPConnection
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from botocore.vendored.requests.packages.urllib3.connectionpool import HTTPConnectionPool
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from botocore.vendored.requests.packages.urllib3.connectionpool import HTTPSConnectionPool
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logger = logging.getLogger(__name__)
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class AWSHTTPResponse(HTTPResponse):
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# The *args, **kwargs is used because the args are slightly
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# different in py2.6 than in py2.7/py3.
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def __init__(self, *args, **kwargs):
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self._status_tuple = kwargs.pop('status_tuple')
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HTTPResponse.__init__(self, *args, **kwargs)
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def _read_status(self):
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if self._status_tuple is not None:
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status_tuple = self._status_tuple
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self._status_tuple = None
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return status_tuple
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else:
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return HTTPResponse._read_status(self)
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class AWSHTTPConnection(HTTPConnection):
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"""HTTPConnection that supports Expect 100-continue.
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This is conceptually a subclass of httplib.HTTPConnection (though
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technically we subclass from urllib3, which subclasses
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httplib.HTTPConnection) and we only override this class to support Expect
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100-continue, which we need for S3. As far as I can tell, this is
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general purpose enough to not be specific to S3, but I'm being
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tentative and keeping it in botocore because I've only tested
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this against AWS services.
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"""
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def __init__(self, *args, **kwargs):
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HTTPConnection.__init__(self, *args, **kwargs)
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self._original_response_cls = self.response_class
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# We'd ideally hook into httplib's states, but they're all
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# __mangled_vars so we use our own state var. This variable is set
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# when we receive an early response from the server. If this value is
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# set to True, any calls to send() are noops. This value is reset to
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# false every time _send_request is called. This is to workaround the
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# fact that py2.6 (and only py2.6) has a separate send() call for the
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# body in _send_request, as opposed to endheaders(), which is where the
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# body is sent in all versions > 2.6.
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self._response_received = False
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def _tunnel(self):
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# Works around a bug in py26 which is fixed in later versions of
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# python. Bug involves hitting an infinite loop if readline() returns
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# nothing as opposed to just ``\r\n``.
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# As much as I don't like having if py2: <foo> code blocks, this seems
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# the cleanest way to handle this workaround. Fortunately, the
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# difference from py26 to py3 is very minimal. We're essentially
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# just overriding the while loop.
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if sys.version_info[:2] != (2, 6):
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return HTTPConnection._tunnel(self)
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# Otherwise we workaround the issue.
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self._set_hostport(self._tunnel_host, self._tunnel_port)
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self.send("CONNECT %s:%d HTTP/1.0\r\n" % (self.host, self.port))
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for header, value in self._tunnel_headers.iteritems():
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self.send("%s: %s\r\n" % (header, value))
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self.send("\r\n")
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response = self.response_class(self.sock, strict = self.strict,
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method = self._method)
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(version, code, message) = response._read_status()
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if code != 200:
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self.close()
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raise socket.error("Tunnel connection failed: %d %s" %
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(code, message.strip()))
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while True:
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line = response.fp.readline()
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if not line:
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break
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if line in (b'\r\n', b'\n', b''):
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break
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def _send_request(self, method, url, body, headers):
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self._response_received = False
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if headers.get('Expect', '') == '100-continue':
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self._expect_header_set = True
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else:
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self._expect_header_set = False
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self.response_class = self._original_response_cls
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rval = HTTPConnection._send_request(
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self, method, url, body, headers)
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self._expect_header_set = False
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return rval
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def _send_output(self, message_body=None):
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self._buffer.extend((b"", b""))
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msg = b"\r\n".join(self._buffer)
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del self._buffer[:]
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# If msg and message_body are sent in a single send() call,
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# it will avoid performance problems caused by the interaction
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# between delayed ack and the Nagle algorithm.
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if isinstance(message_body, bytes):
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msg += message_body
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message_body = None
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self.send(msg)
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if self._expect_header_set:
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# This is our custom behavior. If the Expect header was
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# set, it will trigger this custom behavior.
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logger.debug("Waiting for 100 Continue response.")
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# Wait for 1 second for the server to send a response.
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read, write, exc = select.select([self.sock], [], [self.sock], 1)
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if read:
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self._handle_expect_response(message_body)
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return
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else:
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# From the RFC:
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# Because of the presence of older implementations, the
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# protocol allows ambiguous situations in which a client may
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# send "Expect: 100-continue" without receiving either a 417
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# (Expectation Failed) status or a 100 (Continue) status.
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# Therefore, when a client sends this header field to an origin
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# server (possibly via a proxy) from which it has never seen a
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# 100 (Continue) status, the client SHOULD NOT wait for an
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# indefinite period before sending the request body.
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logger.debug("No response seen from server, continuing to "
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"send the response body.")
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if message_body is not None:
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# message_body was not a string (i.e. it is a file), and
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# we must run the risk of Nagle.
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self.send(message_body)
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def _handle_expect_response(self, message_body):
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# This is called when we sent the request headers containing
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# an Expect: 100-continue header and received a response.
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# We now need to figure out what to do.
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fp = self.sock.makefile('rb', 0)
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try:
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maybe_status_line = fp.readline()
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parts = maybe_status_line.split(None, 2)
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if self._is_100_continue_status(maybe_status_line):
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# Read an empty line as per the RFC.
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fp.readline()
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logger.debug("100 Continue response seen, now sending request body.")
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self._send_message_body(message_body)
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elif len(parts) == 3 and parts[0].startswith(b'HTTP/'):
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# From the RFC:
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# Requirements for HTTP/1.1 origin servers:
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#
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# - Upon receiving a request which includes an Expect
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# request-header field with the "100-continue"
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# expectation, an origin server MUST either respond with
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# 100 (Continue) status and continue to read from the
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# input stream, or respond with a final status code.
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#
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# So if we don't get a 100 Continue response, then
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# whatever the server has sent back is the final response
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# and don't send the message_body.
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logger.debug("Received a non 100 Continue response "
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"from the server, NOT sending request body.")
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status_tuple = (parts[0].decode('ascii'),
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int(parts[1]), parts[2].decode('ascii'))
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response_class = functools.partial(
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AWSHTTPResponse, status_tuple=status_tuple)
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self.response_class = response_class
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self._response_received = True
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finally:
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fp.close()
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def _send_message_body(self, message_body):
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if message_body is not None:
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self.send(message_body)
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def send(self, str):
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if self._response_received:
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logger.debug("send() called, but reseponse already received. "
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"Not sending data.")
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return
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return HTTPConnection.send(self, str)
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def _is_100_continue_status(self, maybe_status_line):
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parts = maybe_status_line.split(None, 2)
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# Check for HTTP/<version> 100 Continue\r\n
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return (
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len(parts) == 3 and parts[0].startswith(b'HTTP/') and
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parts[1] == b'100' and parts[2].startswith(b'Continue'))
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class AWSHTTPSConnection(VerifiedHTTPSConnection):
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pass
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# Now we need to set the methods we overrode from AWSHTTPConnection
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# onto AWSHTTPSConnection. This is just a shortcut to avoid
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# copy/pasting the same code into AWSHTTPSConnection.
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for name, function in AWSHTTPConnection.__dict__.items():
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if inspect.isfunction(function):
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setattr(AWSHTTPSConnection, name, function)
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class AWSRequest(models.RequestEncodingMixin, models.Request):
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def __init__(self, *args, **kwargs):
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self.auth_path = None
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if 'auth_path' in kwargs:
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self.auth_path = kwargs['auth_path']
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del kwargs['auth_path']
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models.Request.__init__(self, *args, **kwargs)
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headers = HTTPHeaders()
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if self.headers is not None:
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for key, value in self.headers.items():
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headers[key] = value
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self.headers = headers
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def prepare(self):
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"""Constructs a :class:`AWSPreparedRequest <AWSPreparedRequest>`."""
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# Eventually I think it would be nice to add hooks into this process.
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p = AWSPreparedRequest(self)
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p.prepare_method(self.method)
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p.prepare_url(self.url, self.params)
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p.prepare_headers(self.headers)
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p.prepare_cookies(self.cookies)
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p.prepare_body(self.data, self.files)
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p.prepare_auth(self.auth)
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return p
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@property
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def body(self):
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p = models.PreparedRequest()
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p.prepare_headers({})
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p.prepare_body(self.data, self.files)
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return p.body
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class AWSPreparedRequest(models.PreparedRequest):
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"""Represents a prepared request.
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:ivar method: HTTP Method
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:ivar url: The full url
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:ivar headers: The HTTP headers to send.
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:ivar body: The HTTP body.
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:ivar hooks: The set of callback hooks.
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In addition to the above attributes, the following attributes are
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available:
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:ivar query_params: The original query parameters.
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:ivar post_param: The original POST params (dict).
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"""
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def __init__(self, original_request):
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self.original = original_request
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super(AWSPreparedRequest, self).__init__()
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self.hooks.setdefault('response', []).append(
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self.reset_stream_on_redirect)
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def reset_stream_on_redirect(self, response, **kwargs):
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if response.status_code in REDIRECT_STATI and \
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self._looks_like_file(self.body):
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logger.debug("Redirect received, rewinding stream: %s", self.body)
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self.reset_stream()
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def _looks_like_file(self, body):
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return hasattr(body, 'read') and hasattr(body, 'seek')
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def reset_stream(self):
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# Trying to reset a stream when there is a no stream will
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# just immediately return. It's not an error, it will produce
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# the same result as if we had actually reset the stream (we'll send
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# the entire body contents again if we need to).
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# Same case if the body is a string/bytes type.
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if self.body is None or isinstance(self.body, six.text_type) or \
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isinstance(self.body, six.binary_type):
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return
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try:
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logger.debug("Rewinding stream: %s", self.body)
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self.body.seek(0)
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except Exception as e:
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logger.debug("Unable to rewind stream: %s", e)
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raise UnseekableStreamError(stream_object=self.body)
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HTTPSConnectionPool.ConnectionCls = AWSHTTPSConnection
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HTTPConnectionPool.ConnectionCls = AWSHTTPConnection
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