text: """
  The MIT License
  
  Copyright (c) 2007 Leah Culver
  
  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:
  
  The above copyright notice and this permission notice shall be included in
  all copies or substantial portions of the Software.
  
  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  THE SOFTWARE.
  """
  
  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'
  
  
  class OAuthError(RuntimeError):
      """Generic exception class."""
      def __init__(self, message='OAuth error occured.'):
          self.mymessage = message
  
  def build_authenticate_header(realm=''):
      """Optional WWW-Authenticate header (401 error)"""
      return {'WWW-Authenticate': 'OAuth realm="%s"' % realm}
  
  def escape(s):
      """Escape a URL including any /."""
      return urllib.quote(s, safe='~')
  
  def _utf8_str(s):
      """Convert unicode to utf-8."""
      if isinstance(s, unicode):
          return s.encode("utf-8")
      else:
          return str(s)
  
  def generate_timestamp():
      """Get seconds since epoch (UTC)."""
      return int(time.time())
  
  def generate_nonce(length=8):
      """Generate pseudorandom number."""
      return ''.join([str(random.randint(0, 9)) for i in range(length)])
  
  
  class OAuthConsumer(object):
      """Consumer of OAuth authentication.
  
      OAuthConsumer is a data type that represents the identity of the Consumer
      via its shared secret with the Service Provider.
  
      """
      key = None
      secret = None
  
      def __init__(self, key, secret):
          self.key = key
          self.secret = secret
  
     
  class OAuthToken(object):
      """OAuthToken is a data type that represents an End User via either an access
      or request token.
      
      key -- the token
      secret -- the token secret
  
      """
      key = None
      secret = None
  
      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})
   
      def from_string(s):
          """ Returns a token from something like:
          oauth_token_secret=xxx&oauth_token=xxx
          """
          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()
  
  
  class OAuthRequest(object):
      """OAuthRequest represents the request and can be serialized.
  
      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:
              if parameter == "oauth_token" : return None
              raise OAuthError('Parameter not found: %s' % parameter)
  
      def _get_timestamp_nonce(self):
          return self.get_parameter('oauth_timestamp'), self.get_parameter(
              'oauth_nonce')
  
      def get_nonoauth_parameters(self):
          """Get any non-OAuth parameters."""
          parameters = {}
          for k, v in self.parameters.iteritems():
              # Ignore oauth parameters.
              if k.find('oauth_') < 0:
                  parameters[k] = v
          return parameters
  
      def to_header(self, realm=''):
          """Serialize as a header for an HTTPAuth request."""
          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}
  
      def to_postdata(self):
          """Serialize as post data for a POST request."""
          return '&'.join(['%s=%s' % (escape(str(k)), escape(str(v))) \
              for k, v in self.parameters.iteritems()])
  
      def to_url(self):
          """Serialize as a URL for a GET request."""
          return '%s?%s' % (self.get_normalized_http_url(), self.to_postdata())
  
      def get_normalized_parameters(self):
          """Return a string that contains the parameters that must be signed."""
  	# Chuck - Make a copy of the parameters so we can modify them
          params = dict(self.parameters)
          try:
              # Exclude the signature if it exists.
              del params['oauth_signature']
          except:
              pass
          # Escape key values before sorting.
          key_values = [(escape(_utf8_str(k)), escape(_utf8_str(v))) \
              for k,v in params.items()]
          # Sort lexicographically, first after key, then after value.
          key_values.sort()
          # Combine key value pairs into a string.
          return '&'.join(['%s=%s' % (k, v) for k, v in key_values])
  
      def get_normalized_http_method(self):
          """Uppercases the http method."""
          return self.http_method.upper()
  
      def get_normalized_http_url(self):
          """Parses the URL and rebuilds it to be scheme://host/path."""
          parts = urlparse.urlparse(self.http_url)
          scheme, netloc, path = parts[:3]
          # Exclude default port numbers.
          if scheme == 'http' and netloc[-3:] == ':80':
              netloc = netloc[:-3]
          elif scheme == 'https' and netloc[-4:] == ':443':
              netloc = netloc[:-4]
          return '%s://%s%s' % (scheme, netloc, path)
  
      def sign_request(self, signature_method, consumer, token):
          """Set the signature parameter to the result of build_signature."""
          # 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):
          """Calls the build signature method within the signature method."""
          return signature_method.build_signature(self, consumer, token)
  
      def from_request(http_method, http_url, headers=None, parameters=None,
              query_string=None):
          """Combines 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:
                  auth_header = auth_header.lstrip('OAuth ')
                  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)
  
      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)
  
      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)
  
      def _split_header(header):
          """Turn Authorization: header into parameters."""
          params = {}
          parts = header.split(',')
          for param in parts:
              # Ignore realm parameter.
              if param.find('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)
  
      def _split_url_string(param_str):
          """Turn URL string into parameters."""
          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)
  
  class OAuthServer(object):
      """A worker to check the validity of a request against a data store."""
      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
  
      def fetch_request_token(self, oauth_request):
          """Processes a request_token request and returns the
          request token on success.
          """
          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
  
      def fetch_access_token(self, oauth_request):
          """Processes an access_token request and returns the
          access token on success.
          """
          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
  
      def verify_request(self, oauth_request):
          """Verifies an api call and checks all the parameters."""
          # -> 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
  
      def authorize_token(self, token, user):
          """Authorize a request token."""
          return self.data_store.authorize_request_token(token, user)
  
      def get_callback(self, oauth_request):
          """Get the callback URL."""
          return oauth_request.get_parameter('oauth_callback')
   
      def build_authenticate_header(self, realm=''):
          """Optional support for the authenticate header."""
          return {'WWW-Authenticate': 'OAuth realm="%s"' % realm}
  
      def _get_version(self, oauth_request):
          """Verify the correct version request for this server."""
          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
  
      def _get_signature_method(self, oauth_request):
          """Figure out the signature with some defaults."""
          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')
          consumer = self.data_store.lookup_consumer(consumer_key)
          if not consumer:
              raise OAuthError('Invalid consumer.')
          return consumer
  
      def _get_token(self, oauth_request, token_type='access'):
          """Try to find the token for the provided request token key."""
          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))
  
  
  class OAuthClient(object):
      """OAuthClient is a worker to attempt to execute a request."""
      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
  
  
  class OAuthDataStore(object):
      """A database abstraction used to lookup consumers and tokens."""
  
      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):
          """-> 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
  
  
  class OAuthSignatureMethod(object):
      """A strategy class that implements a signature method."""
      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 and token.secret:
              key += escape(token.secret)
          raw = '&'.join(sig)
          return key, raw
  
      def build_signature(self, oauth_request, consumer, token):
          """Builds 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):
          """Concatenates 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
  