Added gsutil to depot tools

third_party/gsutil/oauth2_plugin/oauth2_client.py

Index: third_party/gsutil/oauth2_plugin/oauth2_client.py
diff --git a/third_party/gsutil/oauth2_plugin/oauth2_client.py b/third_party/gsutil/oauth2_plugin/oauth2_client.py
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+# Copyright 2010 Google Inc. 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.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License 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.
+
+"""An OAuth2 client library.
+
+This library provides a client implementation of the OAuth2 protocol (see
+http://code.google.com/apis/accounts/docs/OAuth2.html).
+
+**** Experimental API ****
+
+This module is experimental and is subject to modification or removal without
+notice.
+"""
+
+# This implementation is inspired by the implementation in
+# http://code.google.com/p/google-api-python-client/source/browse/oauth2client/,
+# with the following main differences:
+# - This library uses the fancy_urllib monkey patch for urllib to correctly
+#   implement SSL certificate validation.
+# - This library does not assume that client code is using the httplib2 library
+#   to make HTTP requests.
+# - This library implements caching of access tokens independent of refresh
+#   tokens (in the python API client oauth2client, there is a single class that
+#   encapsulates both refresh and access tokens).
+
+
+import cgi
+import datetime
+import errno
+from hashlib import sha1
+import logging
+import os
+import tempfile
+import threading
+import urllib
+import urllib2
+import urlparse
+
+from boto import cacerts
+from third_party import fancy_urllib
+
+try:
+  import json
+except ImportError:
+  try:
+    # Try to import from django, should work on App Engine
+    from django.utils import simplejson as json
+  except ImportError:
+    # Try for simplejson
+    import simplejson as json
+
+LOG = logging.getLogger('oauth2_client')
+# Lock used for checking/exchanging refresh token, so multithreaded
+# operation doesn't attempt concurrent refreshes.
+token_exchange_lock = threading.Lock()
+
+# SHA1 sum of the CA certificates file imported from boto.
+CACERTS_FILE_SHA1SUM = 'ed024a78d9327f8669b3b117d9eac9e3c9460e9b'
+
+class Error(Exception):
+  """Base exception for the OAuth2 module."""
+  pass
+
+
+class AccessTokenRefreshError(Error):
+  """Error trying to exchange a refresh token into an access token."""
+  pass
+
+
+class AuthorizationCodeExchangeError(Error):
+  """Error trying to exchange an authorization code into a refresh token."""
+  pass
+
+
+class TokenCache(object):
+  """Interface for OAuth2 token caches."""
+
+  def PutToken(self, key, value):
+    raise NotImplementedError
+
+  def GetToken(self, key):
+    raise NotImplementedError
+
+
+class NoopTokenCache(TokenCache):
+  """A stub implementation of TokenCache that does nothing."""
+
+  def PutToken(self, key, value):
+    pass
+
+  def GetToken(self, key):
+    return None
+
+
+class InMemoryTokenCache(TokenCache):
+  """An in-memory token cache.
+
+  The cache is implemented by a python dict, and inherits the thread-safety
+  properties of dict.
+  """
+
+  def __init__(self):
+    super(InMemoryTokenCache, self).__init__()
+    self.cache = dict()
+
+  def PutToken(self, key, value):
+    LOG.info('InMemoryTokenCache.PutToken: key=%s', key)
+    self.cache[key] = value
+
+  def GetToken(self, key):
+    value = self.cache.get(key, None)
+    LOG.info('InMemoryTokenCache.GetToken: key=%s%s present',
+             key, ' not' if value is None else '')
+    return value
+
+
+class FileSystemTokenCache(TokenCache):
+  """An implementation of a token cache that persists tokens on disk.
+
+  Each token object in the cache is stored in serialized form in a separate
+  file. The cache file's name can be configured via a path pattern that is
+  parameterized by the key under which a value is cached and optionally the
+  current processes uid as obtained by os.getuid().
+
+  Since file names are generally publicly visible in the system, it is important
+  that the cache key does not leak information about the token's value.  If
+  client code computes cache keys from token values, a cryptographically strong
+  one-way function must be used.
+  """
+
+  def __init__(self, path_pattern=None):
+    """Creates a FileSystemTokenCache.
+
+    Args:
+      path_pattern: Optional string argument to specify the path pattern for
+          cache files.  The argument should be a path with format placeholders
+          '%(key)s' and optionally '%(uid)s'.  If the argument is omitted, the
+          default pattern
+            <tmpdir>/oauth2client-tokencache.%(uid)s.%(key)s
+          is used, where <tmpdir> is replaced with the system temp dir as
+          obtained from tempfile.gettempdir().
+    """
+    super(FileSystemTokenCache, self).__init__()
+    self.path_pattern = path_pattern
+    if not path_pattern:
+      self.path_pattern = os.path.join(
+          tempfile.gettempdir(), 'oauth2_client-tokencache.%(uid)s.%(key)s')
+
+  def CacheFileName(self, key):
+    uid = '_'
+    try:
+      # os.getuid() doesn't seem to work in Windows
+      uid = str(os.getuid())
+    except:
+      pass
+    return self.path_pattern % {'key': key, 'uid': uid}
+
+  def PutToken(self, key, value):
+    """Serializes the value to the key's filename.
+
+    To ensure that written tokens aren't leaked to a different users, we
+     a) unlink an existing cache file, if any (to ensure we don't fall victim
+        to symlink attacks and the like),
+     b) create a new file with O_CREAT | O_EXCL (to ensure nobody is trying to
+        race us)
+     If either of these steps fail, we simply give up (but log a warning). Not
+     caching access tokens is not catastrophic, and failure to create a file
+     can happen for either of the following reasons:
+      - someone is attacking us as above, in which case we want to default to
+        safe operation (not write the token);
+      - another legitimate process is racing us; in this case one of the two
+        will win and write the access token, which is fine;
+      - we don't have permission to remove the old file or write to the
+        specified directory, in which case we can't recover
+
+    Args:
+      key: the refresh_token hash key to store.
+      value: the access_token value to serialize.
+    """
+
+    cache_file = self.CacheFileName(key)
+    LOG.info('FileSystemTokenCache.PutToken: key=%s, cache_file=%s',
+             key, cache_file)
+    try:
+      os.unlink(cache_file)
+    except:
+      # Ignore failure to unlink the file; if the file exists and can't be
+      # unlinked, the subsequent open with O_CREAT | O_EXCL will fail.
+      pass
+
+    flags = os.O_RDWR | os.O_CREAT | os.O_EXCL
+
+    # Accommodate Windows; stolen from python2.6/tempfile.py.
+    if hasattr(os, 'O_NOINHERIT'):
+      flags |= os.O_NOINHERIT
+    if hasattr(os, 'O_BINARY'):
+      flags |= os.O_BINARY
+
+    try:
+      fd = os.open(cache_file, flags, 0600)
+    except (OSError, IOError), e:
+      LOG.warning('FileSystemTokenCache.PutToken: '
+                  'Failed to create cache file %s: %s', cache_file, e)
+      return
+    f = os.fdopen(fd, 'w+b')
+    f.write(value.Serialize())
+    f.close()
+
+  def GetToken(self, key):
+    """Returns a deserialized access token from the key's filename."""
+    value = None
+    cache_file = self.CacheFileName(key)
+    try:
+      f = open(cache_file)
+      value = AccessToken.UnSerialize(f.read())
+      f.close()
+    except (IOError, OSError), e:
+      if e.errno != errno.ENOENT:
+        LOG.warning('FileSystemTokenCache.GetToken: '
+                    'Failed to read cache file %s: %s', cache_file, e)
+    except Exception, e:
+      LOG.warning('FileSystemTokenCache.GetToken: '
+                  'Failed to read cache file %s (possibly corrupted): %s',
+                  cache_file, e)
+
+    LOG.info('FileSystemTokenCache.GetToken: key=%s%s present (cache_file=%s)',
+             key, ' not' if value is None else '', cache_file)
+    return value
+
+
+class OAuth2Provider(object):
+  """Encapsulates information about an OAuth2 provider."""
+
+  def __init__(self, label, authorization_uri, token_uri):
+    """Creates an OAuth2Provider.
+
+    Args:
+      label: A string identifying this oauth2 provider, e.g. "Google".
+      authorization_uri: The provider's authorization URI.
+      token_uri: The provider's token endpoint URI.
+    """
+    self.label = label
+    self.authorization_uri = authorization_uri
+    self.token_uri = token_uri
+
+
+class OAuth2Client(object):
+  """An OAuth2 client."""
+
+  def __init__(self, provider, client_id, client_secret,
+               url_opener=None,
+               proxy=None,
+               access_token_cache=None,
+               datetime_strategy=datetime.datetime):
+    """Creates an OAuth2Client.
+
+    Args:
+      provider: The OAuth2Provider provider this client will authenticate
+          against.
+      client_id: The OAuth2 client ID of this client.
+      client_secret: The OAuth2 client secret of this client.
+      url_opener: An optinal urllib2.OpenerDirector to use for making HTTP
+          requests to the OAuth2 provider's token endpoint.  The provided
+          url_opener *must* be configured to validate server SSL certificates
+          for requests to https connections, and to correctly handle proxying of
+          https requests.  If this argument is omitted or None, a suitable
+          opener based on fancy_urllib is used.
+      proxy: An optional string specifying a HTTP proxy to be used, in the form
+          '<proxy>:<port>'.  This option is only effective if the url_opener has
+          been configured with a fancy_urllib.FancyProxyHandler (this is the
+          case for the default url_opener).
+      access_token_cache: An optional instance of a TokenCache. If omitted or
+          None, an InMemoryTokenCache is used.
+      datetime_strategy: datetime module strategy to use.
+    """
+    self.provider = provider
+    self.client_id = client_id
+    self.client_secret = client_secret
+    # datetime_strategy is used to invoke utcnow() on; it is injected into the
+    # constructor for unit testing purposes.
+    self.datetime_strategy = datetime_strategy
+    self._proxy = proxy
+
+    self.access_token_cache = access_token_cache or InMemoryTokenCache()
+
+    self.ca_certs_file = os.path.join(
+        os.path.dirname(os.path.abspath(cacerts.__file__)), 'cacerts.txt')
+
+    if url_opener is None:
+      # Check that the cert file distributed with boto has not been tampered
+      # with.
+      h = sha1()
+      h.update(file(self.ca_certs_file).read())
+      actual_sha1 = h.hexdigest()
+      if actual_sha1 != CACERTS_FILE_SHA1SUM:
+        raise Error(
+            'CA certificates file does not have expected SHA1 sum; '
+            'expected: %s, actual: %s' % (CACERTS_FILE_SHA1SUM, actual_sha1))
+      # TODO(Google): set user agent?
+      url_opener = urllib2.build_opener(
+          fancy_urllib.FancyProxyHandler(),
+          fancy_urllib.FancyRedirectHandler(),
+          fancy_urllib.FancyHTTPSHandler())
+    self.url_opener = url_opener
+
+  def _TokenRequest(self, request):
+    """Make a requst to this client's provider's token endpoint.
+
+    Args:
+      request: A dict with the request parameteres.
+    Returns:
+      A tuple (response, error) where,
+      - response is the parsed JSON response received from the token endpoint,
+            or None if no parseable response was received, and
+      - error is None if the request succeeded or
+            an Exception if an error occurred.
+    """
+
+    body = urllib.urlencode(request)
+    LOG.debug('_TokenRequest request: %s', body)
+    response = None
+    try:
+      request = fancy_urllib.FancyRequest(
+          self.provider.token_uri, data=body)
+      if self._proxy:
+        request.set_proxy(self._proxy, 'http')
+
+      request.set_ssl_info(ca_certs=self.ca_certs_file)
+      result = self.url_opener.open(request)
+      resp_body = result.read()
+      LOG.debug('_TokenRequest response: %s', resp_body)
+    except urllib2.HTTPError, e:
+      try:
+        response = json.loads(e.read())
+      except:
+        pass
+      return (response, e)
+
+    try:
+      response = json.loads(resp_body)
+    except ValueError, e:
+      return (None, e)
+
+    return (response, None)
+
+  def GetAccessToken(self, refresh_token):
+    """Given a RefreshToken, obtains a corresponding access token.
+
+    First, this client's access token cache is checked for an existing,
+    not-yet-expired access token for the provided refresh token.  If none is
+    found, the client obtains a fresh access token for the provided refresh
+    token from the OAuth2 provider's token endpoint.
+
+    Args:
+      refresh_token: The RefreshToken object which to get an access token for.
+    Returns:
+      The cached or freshly obtained AccessToken.
+    Raises:
+      AccessTokenRefreshError if an error occurs.
+    """
+    # Ensure only one thread at a time attempts to get (and possibly refresh)
+    # the access token. This doesn't prevent concurrent refresh attempts across
+    # multiple gsutil instances, but at least protects against multiple threads
+    # simultaneously attempting to refresh when gsutil -m is used.
+    token_exchange_lock.acquire()
+    try:
+      cache_key = refresh_token.CacheKey()
+      LOG.info('GetAccessToken: checking cache for key %s', cache_key)
+      access_token = self.access_token_cache.GetToken(cache_key)
+      LOG.debug('GetAccessToken: token from cache: %s', access_token)
+      if access_token is None or access_token.ShouldRefresh():
+        LOG.info('GetAccessToken: fetching fresh access token...')
+        access_token = self.FetchAccessToken(refresh_token)
+        LOG.debug('GetAccessToken: fresh access token: %s', access_token)
+        self.access_token_cache.PutToken(cache_key, access_token)
+      return access_token
+    finally:
+      token_exchange_lock.release()
+
+  def FetchAccessToken(self, refresh_token):
+    """Fetches an access token from the provider's token endpoint.
+
+    Given a RefreshToken, fetches an access token from this client's OAuth2
+    provider's token endpoint.
+
+    Args:
+      refresh_token: The RefreshToken object which to get an access token for.
+    Returns:
+      The fetched AccessToken.
+    Raises:
+      AccessTokenRefreshError: if an error occurs.
+    """
+    request = {
+        'grant_type': 'refresh_token',
+        'client_id': self.client_id,
+        'client_secret': self.client_secret,
+        'refresh_token': refresh_token.refresh_token,
+        }
+    LOG.debug('FetchAccessToken request: %s', request)
+
+    response, error = self._TokenRequest(request)
+    LOG.debug(
+        'FetchAccessToken response (error = %s): %s', error, response)
+
+    if error:
+      oauth2_error = ''
+      if response and response['error']:
+        oauth2_error = '; OAuth2 error: %s' % response['error']
+      raise AccessTokenRefreshError(
+          'Failed to exchange refresh token into access token; '
+          'request failed: %s%s' % (error, oauth2_error))
+
+    if 'access_token' not in response:
+      raise AccessTokenRefreshError(
+          'Failed to exchange refresh token into access token; response: %s' %
+          response)
+
+    token_expiry = None
+    if 'expires_in' in response:
+      token_expiry = (
+          self.datetime_strategy.utcnow() +
+          datetime.timedelta(seconds=int(response['expires_in'])))
+
+    return AccessToken(response['access_token'], token_expiry,
+                       datetime_strategy=self.datetime_strategy)
+
+  def GetAuthorizationUri(self, redirect_uri, scopes, extra_params=None):
+    """Gets the OAuth2 authorization URI and the specified scope(s).
+
+    Applications should navigate/redirect the user's user agent to this URI. The
+    user will be shown an approval UI requesting the user to approve access of
+    this client to the requested scopes under the identity of the authenticated
+    end user.
+
+    The application should expect the user agent to be redirected to the
+    specified redirect_uri after the user's approval/disapproval.
+
+    Installed applications may use the special redirect_uri
+    'urn:ietf:wg:oauth:2.0:oob' to indicate that instead of redirecting the
+    browser, the user be shown a confirmation page with a verification code.
+    The application should query the user for this code.
+
+    Args:
+      redirect_uri: Either the string 'urn:ietf:wg:oauth:2.0:oob' for a
+          non-web-based application, or a URI that handles the callback from the
+          authorization server.
+      scopes: A list of strings specifying the OAuth scopes the application
+          requests access to.
+      extra_params: Optional dictionary of additional parameters to be passed to
+          the OAuth2 authorization URI.
+    Returns:
+      The authorization URI for the specified scopes as a string.
+    """
+
+    request = {
+        'response_type': 'code',
+        'client_id': self.client_id,
+        'redirect_uri': redirect_uri,
+        'scope': ' '.join(scopes),
+        }
+
+    if extra_params:
+      request.update(extra_params)
+    url_parts = list(urlparse.urlparse(self.provider.authorization_uri))
+    # 4 is the index of the query part
+    request.update(dict(cgi.parse_qsl(url_parts[4])))
+    url_parts[4] = urllib.urlencode(request)
+    return urlparse.urlunparse(url_parts)
+
+  def ExchangeAuthorizationCode(self, code, redirect_uri, scopes):
+    """Exchanges an authorization code for a refresh token.
+
+    Invokes this client's OAuth2 provider's token endpoint to exchange an
+    authorization code into a refresh token.
+
+    Args:
+      code: the authrorization code.
+      redirect_uri: Either the string 'urn:ietf:wg:oauth:2.0:oob' for a
+          non-web-based application, or a URI that handles the callback from the
+          authorization server.
+      scopes: A list of strings specifying the OAuth scopes the application
+          requests access to.
+    Returns:
+      A tuple consting of the resulting RefreshToken and AccessToken.
+    Raises:
+      AuthorizationCodeExchangeError: if an error occurs.
+    """
+    request = {
+        'grant_type': 'authorization_code',
+        'client_id': self.client_id,
+        'client_secret': self.client_secret,
+        'code': code,
+        'redirect_uri': redirect_uri,
+        'scope': ' '.join(scopes),
+        }
+    LOG.debug('ExchangeAuthorizationCode request: %s', request)
+
+    response, error = self._TokenRequest(request)
+    LOG.debug(
+        'ExchangeAuthorizationCode response (error = %s): %s',
+        error, response)
+
+    if error:
+      oauth2_error = ''
+      if response and response['error']:
+        oauth2_error = '; OAuth2 error: %s' % response['error']
+      raise AuthorizationCodeExchangeError(
+          'Failed to exchange refresh token into access token; '
+          'request failed: %s%s' % (str(error), oauth2_error))
+
+    if not 'access_token' in response:
+      raise AuthorizationCodeExchangeError(
+          'Failed to exchange authorization code into access token; '
+          'response: %s' % response)
+
+    token_expiry = None
+    if 'expires_in' in response:
+      token_expiry = (
+          self.datetime_strategy.utcnow() +
+          datetime.timedelta(seconds=int(response['expires_in'])))
+
+    access_token = AccessToken(response['access_token'], token_expiry,
+                               datetime_strategy=self.datetime_strategy)
+
+    refresh_token = None
+    refresh_token_string = response.get('refresh_token', None)
+
+    token_exchange_lock.acquire()
+    try:
+      if refresh_token_string:
+        refresh_token = RefreshToken(self, refresh_token_string)
+        self.access_token_cache.PutToken(refresh_token.CacheKey(), access_token)
+    finally:
+      token_exchange_lock.release()
+
+    return (refresh_token, access_token)
+
+
+class AccessToken(object):
+  """Encapsulates an OAuth2 access token."""
+
+  def __init__(self, token, expiry, datetime_strategy=datetime.datetime):
+    self.token = token
+    self.expiry = expiry
+    self.datetime_strategy = datetime_strategy
+
+  @staticmethod
+  def UnSerialize(query):
+    """Creates an AccessToken object from its serialized form."""
+
+    def GetValue(d, key):
+      return (d.get(key, [None]))[0]
+    kv = cgi.parse_qs(query)
+    if not kv['token']:
+      return None
+    expiry = None
+    expiry_tuple = GetValue(kv, 'expiry')
+    if expiry_tuple:
+      try:
+        expiry = datetime.datetime(
+            *[int(n) for n in expiry_tuple.split(',')])
+      except:
+        return None
+    return AccessToken(GetValue(kv, 'token'), expiry)
+
+  def Serialize(self):
+    """Serializes this object as URI-encoded key-value pairs."""
+    # There's got to be a better way to serialize a datetime. Unfortunately,
+    # there is no reliable way to convert into a unix epoch.
+    kv = {'token': self.token}
+    if self.expiry:
+      t = self.expiry
+      tupl = (t.year, t.month, t.day, t.hour, t.minute, t.second, t.microsecond)
+      kv['expiry'] = ','.join([str(i) for i in tupl])
+    return urllib.urlencode(kv)
+
+  def ShouldRefresh(self, time_delta=300):
+    """Whether the access token needs to be refreshed.
+
+    Args:
+      time_delta: refresh access token when it expires within time_delta secs.
+
+    Returns:
+      True if the token is expired or about to expire, False if the
+      token should be expected to work.  Note that the token may still
+      be rejected, e.g. if it has been revoked server-side.
+    """
+    if self.expiry is None:
+      return False
+    return (self.datetime_strategy.utcnow()
+            + datetime.timedelta(seconds=time_delta) > self.expiry)
+
+  def __eq__(self, other):
+    return self.token == other.token and self.expiry == other.expiry
+
+  def __ne__(self, other):
+    return not self.__eq__(other)
+
+  def __str__(self):
+    return 'AccessToken(token=%s, expiry=%sZ)' % (self.token, self.expiry)
+
+
+class RefreshToken(object):
+  """Encapsulates an OAuth2 refresh token."""
+
+  def __init__(self, oauth2_client, refresh_token):
+    self.oauth2_client = oauth2_client
+    self.refresh_token = refresh_token
+
+  def CacheKey(self):
+    """Computes a cache key for this refresh token.
+
+    The cache key is computed as the SHA1 hash of the token, and as such
+    satisfies the FileSystemTokenCache requirement that cache keys do not leak
+    information about token values.
+
+    Returns:
+      A hash key for this refresh token.
+    """
+    h = sha1()
+    h.update(self.refresh_token)
+    return h.hexdigest()
+
+  def GetAuthorizationHeader(self):
+    """Gets the access token HTTP authorication header value.
+
+    Returns:
+      The value of an Authorization HTTP header that authenticates
+      requests with an OAuth2 access token based on this refresh token.
+    """
+    return 'Bearer %s' % self.oauth2_client.GetAccessToken(self).token