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File name : awsrequest.py

Content :# Copyright (c) 2012-2013 Mitch Garnaat http://garnaat.org/ # Copyright 2012-2014 Amazon.com, Inc. or its affiliates. All Rights Reserved. # # Licensed under the Apache License, Version 2.0 (the "License"). You # may not use this file except in compliance with the License. A copy of # the License is located at # # http://aws.amazon.com/apache2.0/ # # or in the "license" file accompanying this file. This file is # distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF # ANY KIND, either express or implied. See the License for the specific # language governing permissions and limitations under the License. import sys import logging import functools import socket import urllib3.util from urllib3.connection import VerifiedHTTPSConnection from urllib3.connection import HTTPConnection from urllib3.connectionpool import HTTPConnectionPool from urllib3.connectionpool import HTTPSConnectionPool import botocore.utils from botocore.compat import six from botocore.compat import HTTPHeaders, HTTPResponse, urlunsplit, urlsplit, \ urlencode, MutableMapping from botocore.exceptions import UnseekableStreamError logger = logging.getLogger(__name__) class AWSHTTPResponse(HTTPResponse): # The *args, **kwargs is used because the args are slightly # different in py2.6 than in py2.7/py3. def __init__(self, *args, **kwargs): self._status_tuple = kwargs.pop('status_tuple') HTTPResponse.__init__(self, *args, **kwargs) def _read_status(self): if self._status_tuple is not None: status_tuple = self._status_tuple self._status_tuple = None return status_tuple else: return HTTPResponse._read_status(self) class AWSConnection(object): """Mixin for HTTPConnection that supports Expect 100-continue. This when mixed with a subclass of httplib.HTTPConnection (though technically we subclass from urllib3, which subclasses httplib.HTTPConnection) and we only override this class to support Expect 100-continue, which we need for S3. As far as I can tell, this is general purpose enough to not be specific to S3, but I'm being tentative and keeping it in botocore because I've only tested this against AWS services. """ def __init__(self, *args, **kwargs): super(AWSConnection, self).__init__(*args, **kwargs) self._original_response_cls = self.response_class # We'd ideally hook into httplib's states, but they're all # __mangled_vars so we use our own state var. This variable is set # when we receive an early response from the server. If this value is # set to True, any calls to send() are noops. This value is reset to # false every time _send_request is called. This is to workaround the # fact that py2.6 (and only py2.6) has a separate send() call for the # body in _send_request, as opposed to endheaders(), which is where the # body is sent in all versions > 2.6. self._response_received = False self._expect_header_set = False def close(self): super(AWSConnection, self).close() # Reset all of our instance state we were tracking. self._response_received = False self._expect_header_set = False self.response_class = self._original_response_cls def _send_request(self, method, url, body, headers, *args, **kwargs): self._response_received = False if headers.get('Expect', b'') == b'100-continue': self._expect_header_set = True else: self._expect_header_set = False self.response_class = self._original_response_cls rval = super(AWSConnection, self)._send_request( method, url, body, headers, *args, **kwargs) self._expect_header_set = False return rval def _convert_to_bytes(self, mixed_buffer): # Take a list of mixed str/bytes and convert it # all into a single bytestring. # Any six.text_types will be encoded as utf-8. bytes_buffer = [] for chunk in mixed_buffer: if isinstance(chunk, six.text_type): bytes_buffer.append(chunk.encode('utf-8')) else: bytes_buffer.append(chunk) msg = b"\r\n".join(bytes_buffer) return msg def _send_output(self, message_body=None, *args, **kwargs): self._buffer.extend((b"", b"")) msg = self._convert_to_bytes(self._buffer) del self._buffer[:] # If msg and message_body are sent in a single send() call, # it will avoid performance problems caused by the interaction # between delayed ack and the Nagle algorithm. if isinstance(message_body, bytes): msg += message_body message_body = None self.send(msg) if self._expect_header_set: # This is our custom behavior. If the Expect header was # set, it will trigger this custom behavior. logger.debug("Waiting for 100 Continue response.") # Wait for 1 second for the server to send a response. if urllib3.util.wait_for_read(self.sock, 1): self._handle_expect_response(message_body) return else: # From the RFC: # Because of the presence of older implementations, the # protocol allows ambiguous situations in which a client may # send "Expect: 100-continue" without receiving either a 417 # (Expectation Failed) status or a 100 (Continue) status. # Therefore, when a client sends this header field to an origin # server (possibly via a proxy) from which it has never seen a # 100 (Continue) status, the client SHOULD NOT wait for an # indefinite period before sending the request body. logger.debug("No response seen from server, continuing to " "send the response body.") if message_body is not None: # message_body was not a string (i.e. it is a file), and # we must run the risk of Nagle. self.send(message_body) def _consume_headers(self, fp): # Most servers (including S3) will just return # the CLRF after the 100 continue response. However, # some servers (I've specifically seen this for squid when # used as a straight HTTP proxy) will also inject a # Connection: keep-alive header. To account for this # we'll read until we read '\r\n', and ignore any headers # that come immediately after the 100 continue response. current = None while current != b'\r\n': current = fp.readline() def _handle_expect_response(self, message_body): # This is called when we sent the request headers containing # an Expect: 100-continue header and received a response. # We now need to figure out what to do. fp = self.sock.makefile('rb', 0) try: maybe_status_line = fp.readline() parts = maybe_status_line.split(None, 2) if self._is_100_continue_status(maybe_status_line): self._consume_headers(fp) logger.debug("100 Continue response seen, " "now sending request body.") self._send_message_body(message_body) elif len(parts) == 3 and parts[0].startswith(b'HTTP/'): # From the RFC: # Requirements for HTTP/1.1 origin servers: # # - Upon receiving a request which includes an Expect # request-header field with the "100-continue" # expectation, an origin server MUST either respond with # 100 (Continue) status and continue to read from the # input stream, or respond with a final status code. # # So if we don't get a 100 Continue response, then # whatever the server has sent back is the final response # and don't send the message_body. logger.debug("Received a non 100 Continue response " "from the server, NOT sending request body.") status_tuple = (parts[0].decode('ascii'), int(parts[1]), parts[2].decode('ascii')) response_class = functools.partial( AWSHTTPResponse, status_tuple=status_tuple) self.response_class = response_class self._response_received = True finally: fp.close() def _send_message_body(self, message_body): if message_body is not None: self.send(message_body) def send(self, str): if self._response_received: logger.debug("send() called, but reseponse already received. " "Not sending data.") return return super(AWSConnection, self).send(str) def _is_100_continue_status(self, maybe_status_line): parts = maybe_status_line.split(None, 2) # Check for HTTP/<version> 100 Continue\r\n return ( len(parts) >= 3 and parts[0].startswith(b'HTTP/') and parts[1] == b'100') class AWSHTTPConnection(AWSConnection, HTTPConnection): """ An HTTPConnection that supports 100 Continue behavior. """ class AWSHTTPSConnection(AWSConnection, VerifiedHTTPSConnection): """ An HTTPSConnection that supports 100 Continue behavior. """ class AWSHTTPConnectionPool(HTTPConnectionPool): ConnectionCls = AWSHTTPConnection class AWSHTTPSConnectionPool(HTTPSConnectionPool): ConnectionCls = AWSHTTPSConnection def prepare_request_dict(request_dict, endpoint_url, context=None, user_agent=None): """ This method prepares a request dict to be created into an AWSRequestObject. This prepares the request dict by adding the url and the user agent to the request dict. :type request_dict: dict :param request_dict: The request dict (created from the ``serialize`` module). :type user_agent: string :param user_agent: The user agent to use for this request. :type endpoint_url: string :param endpoint_url: The full endpoint url, which contains at least the scheme, the hostname, and optionally any path components. """ r = request_dict if user_agent is not None: headers = r['headers'] headers['User-Agent'] = user_agent host_prefix = r.get('host_prefix') url = _urljoin(endpoint_url, r['url_path'], host_prefix) if r['query_string']: # NOTE: This is to avoid circular import with utils. This is being # done to avoid moving classes to different modules as to not cause # breaking chainges. percent_encode_sequence = botocore.utils.percent_encode_sequence encoded_query_string = percent_encode_sequence(r['query_string']) if '?' not in url: url += '?%s' % encoded_query_string else: url += '&%s' % encoded_query_string r['url'] = url r['context'] = context if context is None: r['context'] = {} def create_request_object(request_dict): """ This method takes a request dict and creates an AWSRequest object from it. :type request_dict: dict :param request_dict: The request dict (created from the ``prepare_request_dict`` method). :rtype: ``botocore.awsrequest.AWSRequest`` :return: An AWSRequest object based on the request_dict. """ r = request_dict request_object = AWSRequest( method=r['method'], url=r['url'], data=r['body'], headers=r['headers']) request_object.context = r['context'] return request_object def _urljoin(endpoint_url, url_path, host_prefix): p = urlsplit(endpoint_url) # <part> - <index> # scheme - p[0] # netloc - p[1] # path - p[2] # query - p[3] # fragment - p[4] if not url_path or url_path == '/': # If there's no path component, ensure the URL ends with # a '/' for backwards compatibility. if not p[2]: new_path = '/' else: new_path = p[2] elif p[2].endswith('/') and url_path.startswith('/'): new_path = p[2][:-1] + url_path else: new_path = p[2] + url_path new_netloc = p[1] if host_prefix is not None: new_netloc = host_prefix + new_netloc reconstructed = urlunsplit((p[0], new_netloc, new_path, p[3], p[4])) return reconstructed class AWSRequestPreparer(object): """ This class performs preparation on AWSRequest objects similar to that of the PreparedRequest class does in the requests library. However, the logic has been boiled down to meet the specific use cases in botocore. Of note there are the following differences: This class does not heavily prepare the URL. Requests performed many validations and corrections to ensure the URL is properly formatted. Botocore either performs these validations elsewhere or otherwise consistently provides well formatted URLs. This class does not heavily prepare the body. Body preperation is simple and supports only the cases that we document: bytes and file-like objects to determine the content-length. This will also additionally prepare a body that is a dict to be url encoded params string as some signers rely on this. Finally, this class does not support multipart file uploads. This class does not prepare the method, auth or cookies. """ def prepare(self, original): method = original.method url = self._prepare_url(original) body = self._prepare_body(original) headers = self._prepare_headers(original, body) stream_output = original.stream_output return AWSPreparedRequest(method, url, headers, body, stream_output) def _prepare_url(self, original): url = original.url if original.params: params = urlencode(list(original.params.items()), doseq=True) url = '%s?%s' % (url, params) return url def _prepare_headers(self, original, prepared_body=None): headers = HeadersDict(original.headers.items()) # If the transfer encoding or content length is already set, use that if 'Transfer-Encoding' in headers or 'Content-Length' in headers: return headers # Ensure we set the content length when it is expected if original.method not in ('GET', 'HEAD', 'OPTIONS'): length = self._determine_content_length(prepared_body) if length is not None: headers['Content-Length'] = str(length) else: # Failed to determine content length, using chunked # NOTE: This shouldn't ever happen in practice body_type = type(prepared_body) logger.debug('Failed to determine length of %s', body_type) headers['Transfer-Encoding'] = 'chunked' return headers def _to_utf8(self, item): key, value = item if isinstance(key, six.text_type): key = key.encode('utf-8') if isinstance(value, six.text_type): value = value.encode('utf-8') return key, value def _prepare_body(self, original): """Prepares the given HTTP body data.""" body = original.data if body == b'': body = None if isinstance(body, dict): params = [self._to_utf8(item) for item in body.items()] body = urlencode(params, doseq=True) return body def _determine_content_length(self, body): # No body, content length of 0 if not body: return 0 # Try asking the body for it's length try: return len(body) except (AttributeError, TypeError) as e: pass # Try getting the length from a seekable stream if hasattr(body, 'seek') and hasattr(body, 'tell'): orig_pos = body.tell() body.seek(0, 2) end_file_pos = body.tell() body.seek(orig_pos) return end_file_pos - orig_pos # Failed to determine the length return None class AWSRequest(object): """Represents the elements of an HTTP request. This class was originally inspired by requests.models.Request, but has been boiled down to meet the specific use cases in botocore. That being said this class (even in requests) is effectively a named-tuple. """ _REQUEST_PREPARER_CLS = AWSRequestPreparer def __init__(self, method=None, url=None, headers=None, data=None, params=None, auth_path=None, stream_output=False): self._request_preparer = self._REQUEST_PREPARER_CLS() # Default empty dicts for dict params. params = {} if params is None else params self.method = method self.url = url self.headers = HTTPHeaders() self.data = data self.params = params self.auth_path = auth_path self.stream_output = stream_output if headers is not None: for key, value in headers.items(): self.headers[key] = value # This is a dictionary to hold information that is used when # processing the request. What is inside of ``context`` is open-ended. # For example, it may have a timestamp key that is used for holding # what the timestamp is when signing the request. Note that none # of the information that is inside of ``context`` is directly # sent over the wire; the information is only used to assist in # creating what is sent over the wire. self.context = {} def prepare(self): """Constructs a :class:`AWSPreparedRequest <AWSPreparedRequest>`.""" return self._request_preparer.prepare(self) @property def body(self): body = self.prepare().body if isinstance(body, six.text_type): body = body.encode('utf-8') return body class AWSPreparedRequest(object): """A data class representing a finalized request to be sent over the wire. Requests at this stage should be treated as final, and the properties of the request should not be modified. :ivar method: The HTTP Method :ivar url: The full url :ivar headers: The HTTP headers to send. :ivar body: The HTTP body. :ivar stream_output: If the response for this request should be streamed. """ def __init__(self, method, url, headers, body, stream_output): self.method = method self.url = url self.headers = headers self.body = body self.stream_output = stream_output def __repr__(self): fmt = ( '<AWSPreparedRequest stream_output=%s, method=%s, url=%s, ' 'headers=%s>' ) return fmt % (self.stream_output, self.method, self.url, self.headers) def reset_stream(self): """Resets the streaming body to it's initial position. If the request contains a streaming body (a streamable file-like object) seek to the object's initial position to ensure the entire contents of the object is sent. This is a no-op for static bytes-like body types. """ # Trying to reset a stream when there is a no stream will # just immediately return. It's not an error, it will produce # the same result as if we had actually reset the stream (we'll send # the entire body contents again if we need to). # Same case if the body is a string/bytes/bytearray type. non_seekable_types = (six.binary_type, six.text_type, bytearray) if self.body is None or isinstance(self.body, non_seekable_types): return try: logger.debug("Rewinding stream: %s", self.body) self.body.seek(0) except Exception as e: logger.debug("Unable to rewind stream: %s", e) raise UnseekableStreamError(stream_object=self.body) class AWSResponse(object): """A data class representing an HTTP response. This class was originally inspired by requests.models.Response, but has been boiled down to meet the specific use cases in botocore. This has effectively been reduced to a named tuple. :ivar url: The full url. :ivar status_code: The status code of the HTTP response. :ivar headers: The HTTP headers received. :ivar body: The HTTP response body. """ def __init__(self, url, status_code, headers, raw): self.url = url self.status_code = status_code self.headers = HeadersDict(headers) self.raw = raw self._content = None @property def content(self): """Content of the response as bytes.""" if self._content is None: # Read the contents. # NOTE: requests would attempt to call stream and fall back # to a custom generator that would call read in a loop, but # we don't rely on this behavior self._content = bytes().join(self.raw.stream()) or bytes() return self._content @property def text(self): """Content of the response as a proper text type. Uses the encoding type provided in the reponse headers to decode the response content into a proper text type. If the encoding is not present in the headers, UTF-8 is used as a default. """ encoding = botocore.utils.get_encoding_from_headers(self.headers) if encoding: return self.content.decode(encoding) else: return self.content.decode('utf-8') class _HeaderKey(object): def __init__(self, key): self._key = key self._lower = key.lower() def __hash__(self): return hash(self._lower) def __eq__(self, other): return isinstance(other, _HeaderKey) and self._lower == other._lower def __str__(self): return self._key def __repr__(self): return repr(self._key) class HeadersDict(MutableMapping): """A case-insenseitive dictionary to represent HTTP headers. """ def __init__(self, *args, **kwargs): self._dict = {} self.update(*args, **kwargs) def __setitem__(self, key, value): self._dict[_HeaderKey(key)] = value def __getitem__(self, key): return self._dict[_HeaderKey(key)] def __delitem__(self, key): del self._dict[_HeaderKey(key)] def __iter__(self): return (str(key) for key in self._dict) def __len__(self): return len(self._dict) def __repr__(self): return repr(self._dict) def copy(self): return HeadersDict(self.items())

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