157 lines
5.1 KiB
Python
157 lines
5.1 KiB
Python
#!/usr/bin/python
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#
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# Copyright (C) 2008 Google Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""This module provides a common interface for all HTTP requests.
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HttpResponse: Represents the server's response to an HTTP request. Provides
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an interface identical to httplib.HTTPResponse which is the response
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expected from higher level classes which use HttpClient.request.
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GenericHttpClient: Provides an interface (superclass) for an object
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responsible for making HTTP requests. Subclasses of this object are
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used in AtomService and GDataService to make requests to the server. By
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changing the http_client member object, the AtomService is able to make
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HTTP requests using different logic (for example, when running on
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Google App Engine, the http_client makes requests using the App Engine
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urlfetch API).
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"""
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__author__ = 'api.jscudder (Jeff Scudder)'
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import StringIO
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USER_AGENT = '%s GData-Python/2.0.12'
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class Error(Exception):
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pass
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class UnparsableUrlObject(Error):
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pass
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class ContentLengthRequired(Error):
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pass
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class HttpResponse(object):
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def __init__(self, body=None, status=None, reason=None, headers=None):
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"""Constructor for an HttpResponse object.
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HttpResponse represents the server's response to an HTTP request from
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the client. The HttpClient.request method returns a httplib.HTTPResponse
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object and this HttpResponse class is designed to mirror the interface
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exposed by httplib.HTTPResponse.
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Args:
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body: A file like object, with a read() method. The body could also
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be a string, and the constructor will wrap it so that
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HttpResponse.read(self) will return the full string.
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status: The HTTP status code as an int. Example: 200, 201, 404.
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reason: The HTTP status message which follows the code. Example:
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OK, Created, Not Found
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headers: A dictionary containing the HTTP headers in the server's
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response. A common header in the response is Content-Length.
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"""
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if body:
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if hasattr(body, 'read'):
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self._body = body
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else:
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self._body = StringIO.StringIO(body)
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else:
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self._body = None
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if status is not None:
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self.status = int(status)
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else:
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self.status = None
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self.reason = reason
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self._headers = headers or {}
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def getheader(self, name, default=None):
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if name in self._headers:
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return self._headers[name]
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else:
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return default
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def read(self, amt=None):
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if not amt:
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return self._body.read()
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else:
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return self._body.read(amt)
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class GenericHttpClient(object):
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debug = False
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def __init__(self, http_client, headers=None):
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"""
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Args:
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http_client: An object which provides a request method to make an HTTP
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request. The request method in GenericHttpClient performs a
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call-through to the contained HTTP client object.
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headers: A dictionary containing HTTP headers which should be included
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in every HTTP request. Common persistent headers include
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'User-Agent'.
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"""
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self.http_client = http_client
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self.headers = headers or {}
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def request(self, operation, url, data=None, headers=None):
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all_headers = self.headers.copy()
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if headers:
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all_headers.update(headers)
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return self.http_client.request(operation, url, data=data,
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headers=all_headers)
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def get(self, url, headers=None):
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return self.request('GET', url, headers=headers)
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def post(self, url, data, headers=None):
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return self.request('POST', url, data=data, headers=headers)
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def put(self, url, data, headers=None):
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return self.request('PUT', url, data=data, headers=headers)
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def delete(self, url, headers=None):
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return self.request('DELETE', url, headers=headers)
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class GenericToken(object):
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"""Represents an Authorization token to be added to HTTP requests.
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Some Authorization headers included calculated fields (digital
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signatures for example) which are based on the parameters of the HTTP
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request. Therefore the token is responsible for signing the request
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and adding the Authorization header.
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"""
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def perform_request(self, http_client, operation, url, data=None,
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headers=None):
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"""For the GenericToken, no Authorization token is set."""
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return http_client.request(operation, url, data=data, headers=headers)
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def valid_for_scope(self, url):
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"""Tells the caller if the token authorizes access to the desired URL.
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Since the generic token doesn't add an auth header, it is not valid for
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any scope.
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"""
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return False
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