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import cgi
import urllib
import time
import random
import urlparse
import hmac
import binascii
VERSION = '1.0' # Hi Blaine!
HTTP_METHOD = 'GET'
SIGNATURE_METHOD = 'PLAINTEXT'
# Generic exception class
class OAuthError(RuntimeError):
def __init__(self, message='OAuth error occured.'):
self.message = message
# optional WWW-Authenticate header (401 error)
def build_authenticate_header(realm=''):
return {'WWW-Authenticate': 'OAuth realm="%s"' % realm}
# url escape
def escape(s):
# escape '/' too
return urllib.quote(s, safe='~')
# utf-8, please
def _utf8_str(s):
if isinstance(s, unicode):
return s.encode("utf-8")
else:
return str(s)
# util function: current timestamp
# seconds since epoch (UTC)
def generate_timestamp():
return int(time.time())
# util function: nonce
# pseudorandom number
def generate_nonce(length=8):
return ''.join([str(random.randint(0, 9)) for i in range(length)])
# OAuthConsumer is a data type that represents the identity of the Consumer
# via its shared secret with the Service Provider.
class OAuthConsumer(object):
key = None
secret = None
def __init__(self, key, secret):
self.key = key
self.secret = secret
# OAuthToken is a data type that represents an End User via either an access
# or request token.
class OAuthToken(object):
# access tokens and request tokens
key = None
secret = None
'''
key = the token
secret = the token secret
'''
def __init__(self, key, secret):
self.key = key
self.secret = secret
def to_string(self):
return urllib.urlencode({'oauth_token': self.key, 'oauth_token_secret': self.secret})
# return a token from something like:
# oauth_token_secret=digg&oauth_token=digg
# @staticmethod
def from_string(s):
params = cgi.parse_qs(s, keep_blank_values=False)
key = params['oauth_token'][0]
secret = params['oauth_token_secret'][0]
return OAuthToken(key, secret)
from_string = staticmethod(from_string)
def __str__(self):
return self.to_string()
# OAuthRequest represents the request and can be serialized
class OAuthRequest(object):
'''
OAuth parameters:
- oauth_consumer_key
- oauth_token
- oauth_signature_method
- oauth_signature
- oauth_timestamp
- oauth_nonce
- oauth_version
... any additional parameters, as defined by the Service Provider.
'''
parameters = None # oauth parameters
http_method = HTTP_METHOD
http_url = None
version = VERSION
def __init__(self, http_method=HTTP_METHOD, http_url=None, parameters=None):
self.http_method = http_method
self.http_url = http_url
self.parameters = parameters or {}
def set_parameter(self, parameter, value):
self.parameters[parameter] = value
def get_parameter(self, parameter):
try:
return self.parameters[parameter]
except:
raise OAuthError('Parameter not found: %s' % parameter)
def _get_timestamp_nonce(self):
return self.get_parameter('oauth_timestamp'), self.get_parameter('oauth_nonce')
# get any non-oauth parameters
def get_nonoauth_parameters(self):
parameters = {}
for k, v in self.parameters.iteritems():
# ignore oauth parameters
if k.find('oauth_') < 0:
parameters[k] = v
return parameters
# serialize as a header for an HTTPAuth request
def to_header(self, realm=''):
auth_header = 'OAuth realm="%s"' % realm
# add the oauth parameters
if self.parameters:
for k, v in self.parameters.iteritems():
if k[:6] == 'oauth_':
auth_header += ', %s="%s"' % (k, escape(str(v)))
return {'Authorization': auth_header}
# serialize as post data for a POST request
def to_postdata(self):
return '&'.join(['%s=%s' % (escape(str(k)), escape(str(v))) for k, v in self.parameters.iteritems()])
# serialize as a url for a GET request
def to_url(self):
return '%s?%s' % (self.get_normalized_http_url(), self.to_postdata())
# return a string that consists of all the parameters that need to be signed
def get_normalized_parameters(self):
params = self.parameters
try:
# exclude the signature if it exists
del params['oauth_signature']
except:
pass
key_values = params.items()
# sort lexicographically, first after key, then after value
key_values.sort()
# combine key value pairs in string and escape
return '&'.join(['%s=%s' % (escape(_utf8_str(k)), escape(_utf8_str(v))) for k, v in key_values])
# just uppercases the http method
def get_normalized_http_method(self):
return self.http_method.upper()
# parses the url and rebuilds it to be scheme://host/path
def get_normalized_http_url(self):
parts = urlparse.urlparse(self.http_url)
url_string = '%s://%s%s' % (parts[0], parts[1], parts[2]) # scheme, netloc, path
return url_string
# set the signature parameter to the result of build_signature
def sign_request(self, signature_method, consumer, token):
# set the signature method
self.set_parameter('oauth_signature_method', signature_method.get_name())
# set the signature
self.set_parameter('oauth_signature', self.build_signature(signature_method, consumer, token))
def build_signature(self, signature_method, consumer, token):
# call the build signature method within the signature method
return signature_method.build_signature(self, consumer, token)
# @staticmethod
def from_request(http_method, http_url, headers=None, parameters=None, query_string=None):
# combine multiple parameter sources
if parameters is None:
parameters = {}
# headers
if headers and 'Authorization' in headers:
auth_header = headers['Authorization']
# check that the authorization header is OAuth
if auth_header.index('OAuth') > -1:
try:
# get the parameters from the header
header_params = OAuthRequest._split_header(auth_header)
parameters.update(header_params)
except:
raise OAuthError('Unable to parse OAuth parameters from Authorization header.')
# GET or POST query string
if query_string:
query_params = OAuthRequest._split_url_string(query_string)
parameters.update(query_params)
# URL parameters
param_str = urlparse.urlparse(http_url)[4] # query
url_params = OAuthRequest._split_url_string(param_str)
parameters.update(url_params)
if parameters:
return OAuthRequest(http_method, http_url, parameters)
return None
from_request = staticmethod(from_request)
# @staticmethod
def from_consumer_and_token(oauth_consumer, token=None, http_method=HTTP_METHOD, http_url=None, parameters=None):
if not parameters:
parameters = {}
defaults = {
'oauth_consumer_key': oauth_consumer.key,
'oauth_timestamp': generate_timestamp(),
'oauth_nonce': generate_nonce(),
'oauth_version': OAuthRequest.version,
}
defaults.update(parameters)
parameters = defaults
if token:
parameters['oauth_token'] = token.key
return OAuthRequest(http_method, http_url, parameters)
from_consumer_and_token = staticmethod(from_consumer_and_token)
# @staticmethod
def from_token_and_callback(token, callback=None, http_method=HTTP_METHOD, http_url=None, parameters=None):
if not parameters:
parameters = {}
parameters['oauth_token'] = token.key
if callback:
parameters['oauth_callback'] = callback
return OAuthRequest(http_method, http_url, parameters)
from_token_and_callback = staticmethod(from_token_and_callback)
# util function: turn Authorization: header into parameters, has to do some unescaping
# @staticmethod
def _split_header(header):
params = {}
parts = header.split(',')
for param in parts:
# ignore realm parameter
if param.find('OAuth realm') > -1:
continue
# remove whitespace
param = param.strip()
# split key-value
param_parts = param.split('=', 1)
# remove quotes and unescape the value
params[param_parts[0]] = urllib.unquote(param_parts[1].strip('\"'))
return params
_split_header = staticmethod(_split_header)
# util function: turn url string into parameters, has to do some unescaping
# @staticmethod
def _split_url_string(param_str):
parameters = cgi.parse_qs(param_str, keep_blank_values=False)
for k, v in parameters.iteritems():
parameters[k] = urllib.unquote(v[0])
return parameters
_split_url_string = staticmethod(_split_url_string)
# OAuthServer is a worker to check a requests validity against a data store
class OAuthServer(object):
timestamp_threshold = 300 # in seconds, five minutes
version = VERSION
signature_methods = None
data_store = None
def __init__(self, data_store=None, signature_methods=None):
self.data_store = data_store
self.signature_methods = signature_methods or {}
def set_data_store(self, data_store):
self.data_store = data_store
def get_data_store(self):
return self.data_store
def add_signature_method(self, signature_method):
self.signature_methods[signature_method.get_name()] = signature_method
return self.signature_methods
# process a request_token request
# returns the request token on success
def fetch_request_token(self, oauth_request):
try:
# get the request token for authorization
token = self._get_token(oauth_request, 'request')
except OAuthError:
# no token required for the initial token request
version = self._get_version(oauth_request)
consumer = self._get_consumer(oauth_request)
self._check_signature(oauth_request, consumer, None)
# fetch a new token
token = self.data_store.fetch_request_token(consumer)
return token
# process an access_token request
# returns the access token on success
def fetch_access_token(self, oauth_request):
version = self._get_version(oauth_request)
consumer = self._get_consumer(oauth_request)
# get the request token
token = self._get_token(oauth_request, 'request')
self._check_signature(oauth_request, consumer, token)
new_token = self.data_store.fetch_access_token(consumer, token)
return new_token
# verify an api call, checks all the parameters
def verify_request(self, oauth_request):
# -> consumer and token
version = self._get_version(oauth_request)
consumer = self._get_consumer(oauth_request)
# get the access token
token = self._get_token(oauth_request, 'access')
self._check_signature(oauth_request, consumer, token)
parameters = oauth_request.get_nonoauth_parameters()
return consumer, token, parameters
# authorize a request token
def authorize_token(self, token, user):
return self.data_store.authorize_request_token(token, user)
# get the callback url
def get_callback(self, oauth_request):
return oauth_request.get_parameter('oauth_callback')
# optional support for the authenticate header
def build_authenticate_header(self, realm=''):
return {'WWW-Authenticate': 'OAuth realm="%s"' % realm}
# verify the correct version request for this server
def _get_version(self, oauth_request):
try:
version = oauth_request.get_parameter('oauth_version')
except:
version = VERSION
if version and version != self.version:
raise OAuthError('OAuth version %s not supported.' % str(version))
return version
# figure out the signature with some defaults
def _get_signature_method(self, oauth_request):
try:
signature_method = oauth_request.get_parameter('oauth_signature_method')
except:
signature_method = SIGNATURE_METHOD
try:
# get the signature method object
signature_method = self.signature_methods[signature_method]
except:
signature_method_names = ', '.join(self.signature_methods.keys())
raise OAuthError('Signature method %s not supported try one of the following: %s' % (signature_method, signature_method_names))
return signature_method
def _get_consumer(self, oauth_request):
consumer_key = oauth_request.get_parameter('oauth_consumer_key')
if not consumer_key:
raise OAuthError('Invalid consumer key.')
consumer = self.data_store.lookup_consumer(consumer_key)
if not consumer:
raise OAuthError('Invalid consumer.')
return consumer
# try to find the token for the provided request token key
def _get_token(self, oauth_request, token_type='access'):
token_field = oauth_request.get_parameter('oauth_token')
token = self.data_store.lookup_token(token_type, token_field)
if not token:
raise OAuthError('Invalid %s token: %s' % (token_type, token_field))
return token
def _check_signature(self, oauth_request, consumer, token):
timestamp, nonce = oauth_request._get_timestamp_nonce()
self._check_timestamp(timestamp)
self._check_nonce(consumer, token, nonce)
signature_method = self._get_signature_method(oauth_request)
try:
signature = oauth_request.get_parameter('oauth_signature')
except:
raise OAuthError('Missing signature.')
# validate the signature
valid_sig = signature_method.check_signature(oauth_request, consumer, token, signature)
if not valid_sig:
key, base = signature_method.build_signature_base_string(oauth_request, consumer, token)
raise OAuthError('Invalid signature. Expected signature base string: %s' % base)
built = signature_method.build_signature(oauth_request, consumer, token)
def _check_timestamp(self, timestamp):
# verify that timestamp is recentish
timestamp = int(timestamp)
now = int(time.time())
lapsed = now - timestamp
if lapsed > self.timestamp_threshold:
raise OAuthError('Expired timestamp: given %d and now %s has a greater difference than threshold %d' % (timestamp, now, self.timestamp_threshold))
def _check_nonce(self, consumer, token, nonce):
# verify that the nonce is uniqueish
nonce = self.data_store.lookup_nonce(consumer, token, nonce)
if nonce:
raise OAuthError('Nonce already used: %s' % str(nonce))
# OAuthClient is a worker to attempt to execute a request
class OAuthClient(object):
consumer = None
token = None
def __init__(self, oauth_consumer, oauth_token):
self.consumer = oauth_consumer
self.token = oauth_token
def get_consumer(self):
return self.consumer
def get_token(self):
return self.token
def fetch_request_token(self, oauth_request):
# -> OAuthToken
raise NotImplementedError
def fetch_access_token(self, oauth_request):
# -> OAuthToken
raise NotImplementedError
def access_resource(self, oauth_request):
# -> some protected resource
raise NotImplementedError
# OAuthDataStore is a database abstraction used to lookup consumers and tokens
class OAuthDataStore(object):
def lookup_consumer(self, key):
# -> OAuthConsumer
raise NotImplementedError
def lookup_token(self, oauth_consumer, token_type, token_token):
# -> OAuthToken
raise NotImplementedError
def lookup_nonce(self, oauth_consumer, oauth_token, nonce, timestamp):
# -> OAuthToken
raise NotImplementedError
def fetch_request_token(self, oauth_consumer):
# -> OAuthToken
raise NotImplementedError
def fetch_access_token(self, oauth_consumer, oauth_token):
# -> OAuthToken
raise NotImplementedError
def authorize_request_token(self, oauth_token, user):
# -> OAuthToken
raise NotImplementedError
# OAuthSignatureMethod is a strategy class that implements a signature method
class OAuthSignatureMethod(object):
def get_name(self):
# -> str
raise NotImplementedError
def build_signature_base_string(self, oauth_request, oauth_consumer, oauth_token):
# -> str key, str raw
raise NotImplementedError
def build_signature(self, oauth_request, oauth_consumer, oauth_token):
# -> str
raise NotImplementedError
def check_signature(self, oauth_request, consumer, token, signature):
built = self.build_signature(oauth_request, consumer, token)
return built == signature
class OAuthSignatureMethod_HMAC_SHA1(OAuthSignatureMethod):
def get_name(self):
return 'HMAC-SHA1'
def build_signature_base_string(self, oauth_request, consumer, token):
sig = (
escape(oauth_request.get_normalized_http_method()),
escape(oauth_request.get_normalized_http_url()),
escape(oauth_request.get_normalized_parameters()),
)
key = '%s&' % escape(consumer.secret)
if token:
key += escape(token.secret)
raw = '&'.join(sig)
return key, raw
def build_signature(self, oauth_request, consumer, token):
# build the base signature string
key, raw = self.build_signature_base_string(oauth_request, consumer, token)
# hmac object
try:
import hashlib # 2.5
hashed = hmac.new(key, raw, hashlib.sha1)
except:
import sha # deprecated
hashed = hmac.new(key, raw, sha)
# calculate the digest base 64
return binascii.b2a_base64(hashed.digest())[:-1]
class OAuthSignatureMethod_PLAINTEXT(OAuthSignatureMethod):
def get_name(self):
return 'PLAINTEXT'
def build_signature_base_string(self, oauth_request, consumer, token):
# concatenate the consumer key and secret
sig = '%s&' % escape(consumer.secret)
if token:
sig = sig + escape(token.secret)
return sig, sig
def build_signature(self, oauth_request, consumer, token):
key, raw = self.build_signature_base_string(oauth_request, consumer, token)
return key