Replace custom blob gRPC API with ByteStream

client/third_party/google/auth/jwt.py

+# Copyright 2016 Google Inc.
+#
+# 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.
+
+"""JSON Web Tokens
+
+Provides support for creating (encoding) and verifying (decoding) JWTs,
+especially JWTs generated and consumed by Google infrastructure.
+
+See `rfc7519`_ for more details on JWTs.
+
+To encode a JWT use :func:`encode`::
+
+    from google.auth import crypto
+    from google.auth import jwt
+
+    signer = crypt.Signer(private_key)
+    payload = {'some': 'payload'}
+    encoded = jwt.encode(signer, payload)
+
+To decode a JWT and verify claims use :func:`decode`::
+
+    claims = jwt.decode(encoded, certs=public_certs)
+
+You can also skip verification::
+
+    claims = jwt.decode(encoded, verify=False)
+
+.. _rfc7519: https://tools.ietf.org/html/rfc7519
+
+"""
+
+import base64
+import collections
+import copy
+import datetime
+import json
+
+import cachetools
+from six.moves import urllib
+
+from google.auth import _helpers
+from google.auth import _service_account_info
+from google.auth import crypt
+from google.auth import exceptions
+import google.auth.credentials
+
+_DEFAULT_TOKEN_LIFETIME_SECS = 3600  # 1 hour in seconds
+_DEFAULT_MAX_CACHE_SIZE = 10
+
+
+def encode(signer, payload, header=None, key_id=None):
+    """Make a signed JWT.
+
+    Args:
+        signer (google.auth.crypt.Signer): The signer used to sign the JWT.
+        payload (Mapping[str, str]): The JWT payload.
+        header (Mapping[str, str]): Additional JWT header payload.
+        key_id (str): The key id to add to the JWT header. If the
+            signer has a key id it will be used as the default. If this is
+            specified it will override the signer's key id.
+
+    Returns:
+        bytes: The encoded JWT.
+    """
+    if header is None:
+        header = {}
+
+    if key_id is None:
+        key_id = signer.key_id
+
+    header.update({'typ': 'JWT', 'alg': 'RS256'})
+
+    if key_id is not None:
+        header['kid'] = key_id
+
+    segments = [
+        base64.urlsafe_b64encode(json.dumps(header).encode('utf-8')),
+        base64.urlsafe_b64encode(json.dumps(payload).encode('utf-8')),
+    ]
+
+    signing_input = b'.'.join(segments)
+    signature = signer.sign(signing_input)
+    segments.append(base64.urlsafe_b64encode(signature))
+
+    return b'.'.join(segments)
+
+
+def _decode_jwt_segment(encoded_section):
+    """Decodes a single JWT segment."""
+    section_bytes = _helpers.padded_urlsafe_b64decode(encoded_section)
+    try:
+        return json.loads(section_bytes.decode('utf-8'))
+    except ValueError:
+        raise ValueError('Can\'t parse segment: {0}'.format(section_bytes))
+
+
+def _unverified_decode(token):
+    """Decodes a token and does no verification.
+
+    Args:
+        token (Union[str, bytes]): The encoded JWT.
+
+    Returns:
+        Tuple[str, str, str, str]: header, payload, signed_section, and
+            signature.
+
+    Raises:
+        ValueError: if there are an incorrect amount of segments in the token.
+    """
+    token = _helpers.to_bytes(token)
+
+    if token.count(b'.') != 2:
+        raise ValueError(
+            'Wrong number of segments in token: {0}'.format(token))
+
+    encoded_header, encoded_payload, signature = token.split(b'.')
+    signed_section = encoded_header + b'.' + encoded_payload
+    signature = _helpers.padded_urlsafe_b64decode(signature)
+
+    # Parse segments
+    header = _decode_jwt_segment(encoded_header)
+    payload = _decode_jwt_segment(encoded_payload)
+
+    return header, payload, signed_section, signature
+
+
+def decode_header(token):
+    """Return the decoded header of a token.
+
+    No verification is done. This is useful to extract the key id from
+    the header in order to acquire the appropriate certificate to verify
+    the token.
+
+    Args:
+        token (Union[str, bytes]): the encoded JWT.
+
+    Returns:
+        Mapping: The decoded JWT header.
+    """
+    header, _, _, _ = _unverified_decode(token)
+    return header
+
+
+def _verify_iat_and_exp(payload):
+    """Verifies the ``iat`` (Issued At) and ``exp`` (Expires) claims in a token
+    payload.
+
+    Args:
+        payload (Mapping[str, str]): The JWT payload.
+
+    Raises:
+        ValueError: if any checks failed.
+    """
+    now = _helpers.datetime_to_secs(_helpers.utcnow())
+
+    # Make sure the iat and exp claims are present.
+    for key in ('iat', 'exp'):
+        if key not in payload:
+            raise ValueError(
+                'Token does not contain required claim {}'.format(key))
+
+    # Make sure the token wasn't issued in the future.
+    iat = payload['iat']
+    # Err on the side of accepting a token that is slightly early to account
+    # for clock skew.
+    earliest = iat - _helpers.CLOCK_SKEW_SECS
+    if now < earliest:
+        raise ValueError('Token used too early, {} < {}'.format(now, iat))
+
+    # Make sure the token wasn't issued in the past.
+    exp = payload['exp']
+    # Err on the side of accepting a token that is slightly out of date
+    # to account for clow skew.
+    latest = exp + _helpers.CLOCK_SKEW_SECS
+    if latest < now:
+        raise ValueError('Token expired, {} < {}'.format(latest, now))
+
+
+def decode(token, certs=None, verify=True, audience=None):
+    """Decode and verify a JWT.
+
+    Args:
+        token (str): The encoded JWT.
+        certs (Union[str, bytes, Mapping[str, Union[str, bytes]]]): The
+            certificate used to validate the JWT signatyre. If bytes or string,
+            it must the the public key certificate in PEM format. If a mapping,
+            it must be a mapping of key IDs to public key certificates in PEM
+            format. The mapping must contain the same key ID that's specified
+            in the token's header.
+        verify (bool): Whether to perform signature and claim validation.
+            Verification is done by default.
+        audience (str): The audience claim, 'aud', that this JWT should
+            contain. If None then the JWT's 'aud' parameter is not verified.
+
+    Returns:
+        Mapping[str, str]: The deserialized JSON payload in the JWT.
+
+    Raises:
+        ValueError: if any verification checks failed.
+    """
+    header, payload, signed_section, signature = _unverified_decode(token)
+
+    if not verify:
+        return payload
+
+    # If certs is specified as a dictionary of key IDs to certificates, then
+    # use the certificate identified by the key ID in the token header.
+    if isinstance(certs, collections.Mapping):
+        key_id = header.get('kid')
+        if key_id:
+            if key_id not in certs:
+                raise ValueError(
+                    'Certificate for key id {} not found.'.format(key_id))
+            certs_to_check = [certs[key_id]]
+        # If there's no key id in the header, check against all of the certs.
+        else:
+            certs_to_check = certs.values()
+    else:
+        certs_to_check = certs
+
+    # Verify that the signature matches the message.
+    if not crypt.verify_signature(signed_section, signature, certs_to_check):
+        raise ValueError('Could not verify token signature.')
+
+    # Verify the issued at and created times in the payload.
+    _verify_iat_and_exp(payload)
+
+    # Check audience.
+    if audience is not None:
+        claim_audience = payload.get('aud')
+        if audience != claim_audience:
+            raise ValueError(
+                'Token has wrong audience {}, expected {}'.format(
+                    claim_audience, audience))
+
+    return payload
+
+
+class Credentials(google.auth.credentials.Signing,
+                  google.auth.credentials.Credentials):
+    """Credentials that use a JWT as the bearer token.
+
+    These credentials require an "audience" claim. This claim identifies the
+    intended recipient of the bearer token.
+
+    The constructor arguments determine the claims for the JWT that is
+    sent with requests. Usually, you'll construct these credentials with
+    one of the helper constructors as shown in the next section.
+
+    To create JWT credentials using a Google service account private key
+    JSON file::
+
+        audience = 'https://pubsub.googleapis.com/google.pubsub.v1.Publisher'
+        credentials = jwt.Credentials.from_service_account_file(
+            'service-account.json',
+            audience=audience)
+
+    If you already have the service account file loaded and parsed::
+
+        service_account_info = json.load(open('service_account.json'))
+        credentials = jwt.Credentials.from_service_account_info(
+            service_account_info,
+            audience=audience)
+
+    Both helper methods pass on arguments to the constructor, so you can
+    specify the JWT claims::
+
+        credentials = jwt.Credentials.from_service_account_file(
+            'service-account.json',
+            audience=audience,
+            additional_claims={'meta': 'data'})
+
+    You can also construct the credentials directly if you have a
+    :class:`~google.auth.crypt.Signer` instance::
+
+        credentials = jwt.Credentials(
+            signer,
+            issuer='your-issuer',
+            subject='your-subject',
+            audience=audience)
+
+    The claims are considered immutable. If you want to modify the claims,
+    you can easily create another instance using :meth:`with_claims`::
+
+        new_audience = (
+            'https://pubsub.googleapis.com/google.pubsub.v1.Subscriber')
+        new_credentials = credentials.with_claims(audience=new_audience)
+    """
+
+    def __init__(self, signer, issuer, subject, audience,
+                 additional_claims=None,
+                 token_lifetime=_DEFAULT_TOKEN_LIFETIME_SECS):
+        """
+        Args:
+            signer (google.auth.crypt.Signer): The signer used to sign JWTs.
+            issuer (str): The `iss` claim.
+            subject (str): The `sub` claim.
+            audience (str): the `aud` claim. The intended audience for the
+                credentials.
+            additional_claims (Mapping[str, str]): Any additional claims for
+                the JWT payload.
+            token_lifetime (int): The amount of time in seconds for
+                which the token is valid. Defaults to 1 hour.
+        """
+        super(Credentials, self).__init__()
+        self._signer = signer
+        self._issuer = issuer
+        self._subject = subject
+        self._audience = audience
+        self._token_lifetime = token_lifetime
+
+        if additional_claims is None:
+            additional_claims = {}
+
+        self._additional_claims = additional_claims
+
+    @classmethod
+    def _from_signer_and_info(cls, signer, info, **kwargs):
+        """Creates a Credentials instance from a signer and service account
+        info.
+
+        Args:
+            signer (google.auth.crypt.Signer): The signer used to sign JWTs.
+            info (Mapping[str, str]): The service account info.
+            kwargs: Additional arguments to pass to the constructor.
+
+        Returns:
+            google.auth.jwt.Credentials: The constructed credentials.
+
+        Raises:
+            ValueError: If the info is not in the expected format.
+        """
+        kwargs.setdefault('subject', info['client_email'])
+        kwargs.setdefault('issuer', info['client_email'])
+        return cls(signer, **kwargs)
+
+    @classmethod
+    def from_service_account_info(cls, info, **kwargs):
+        """Creates an Credentials instance from a dictionary.
+
+        Args:
+            info (Mapping[str, str]): The service account info in Google
+                format.
+            kwargs: Additional arguments to pass to the constructor.
+
+        Returns:
+            google.auth.jwt.Credentials: The constructed credentials.
+
+        Raises:
+            ValueError: If the info is not in the expected format.
+        """
+        signer = _service_account_info.from_dict(
+            info, require=['client_email'])
+        return cls._from_signer_and_info(signer, info, **kwargs)
+
+    @classmethod
+    def from_service_account_file(cls, filename, **kwargs):
+        """Creates a Credentials instance from a service account .json file
+        in Google format.
+
+        Args:
+            filename (str): The path to the service account .json file.
+            kwargs: Additional arguments to pass to the constructor.
+
+        Returns:
+            google.auth.jwt.Credentials: The constructed credentials.
+        """
+        info, signer = _service_account_info.from_filename(
+            filename, require=['client_email'])
+        return cls._from_signer_and_info(signer, info, **kwargs)
+
+    @classmethod
+    def from_signing_credentials(cls, credentials, audience, **kwargs):
+        """Creates a new :class:`google.auth.jwt.Credentials` instance from an
+        existing :class:`google.auth.credentials.Signing` instance.
+
+        The new instance will use the same signer as the existing instance and
+        will use the existing instance's signer email as the issuer and
+        subject by default.
+
+        Example::
+
+            svc_creds = service_account.Credentials.from_service_account_file(
+                'service_account.json')
+            audience = (
+                'https://pubsub.googleapis.com/google.pubsub.v1.Publisher')
+            jwt_creds = jwt.Credentials.from_signing_credentials(
+                svc_creds, audience=audience)
+
+        Args:
+            credentials (google.auth.credentials.Signing): The credentials to
+                use to construct the new credentials.
+            audience (str): the `aud` claim. The intended audience for the
+                credentials.
+            kwargs: Additional arguments to pass to the constructor.
+
+        Returns:
+            google.auth.jwt.Credentials: A new Credentials instance.
+        """
+        kwargs.setdefault('issuer', credentials.signer_email)
+        kwargs.setdefault('subject', credentials.signer_email)
+        return cls(
+            credentials.signer,
+            audience=audience,
+            **kwargs)
+
+    def with_claims(self, issuer=None, subject=None, audience=None,
+                    additional_claims=None):
+        """Returns a copy of these credentials with modified claims.
+
+        Args:
+            issuer (str): The `iss` claim. If unspecified the current issuer
+                claim will be used.
+            subject (str): The `sub` claim. If unspecified the current subject
+                claim will be used.
+            audience (str): the `aud` claim. If unspecified the current
+                audience claim will be used.
+            additional_claims (Mapping[str, str]): Any additional claims for
+                the JWT payload. This will be merged with the current
+                additional claims.
+
+        Returns:
+            google.auth.jwt.Credentials: A new credentials instance.
+        """
+        new_additional_claims = copy.deepcopy(self._additional_claims)
+        new_additional_claims.update(additional_claims or {})
+
+        return Credentials(
+            self._signer,
+            issuer=issuer if issuer is not None else self._issuer,
+            subject=subject if subject is not None else self._subject,
+            audience=audience if audience is not None else self._audience,
+            additional_claims=new_additional_claims)
+
+    def _make_jwt(self):
+        """Make a signed JWT.
+
+        Returns:
+            Tuple[bytes, datetime]: The encoded JWT and the expiration.
+        """
+        now = _helpers.utcnow()
+        lifetime = datetime.timedelta(seconds=self._token_lifetime)
+        expiry = now + lifetime
+
+        payload = {
+            'iss': self._issuer,
+            'sub': self._subject,
+            'iat': _helpers.datetime_to_secs(now),
+            'exp': _helpers.datetime_to_secs(expiry),
+            'aud': self._audience,
+        }
+
+        payload.update(self._additional_claims)
+
+        jwt = encode(self._signer, payload)
+
+        return jwt, expiry
+
+    def refresh(self, request):
+        """Refreshes the access token.
+
+        Args:
+            request (Any): Unused.
+        """
+        # pylint: disable=unused-argument
+        # (pylint doesn't correctly recognize overridden methods.)
+        self.token, self.expiry = self._make_jwt()
+
+    @_helpers.copy_docstring(google.auth.credentials.Signing)
+    def sign_bytes(self, message):
+        return self._signer.sign(message)
+
+    @property
+    @_helpers.copy_docstring(google.auth.credentials.Signing)
+    def signer_email(self):
+        return self._issuer
+
+    @property
+    @_helpers.copy_docstring(google.auth.credentials.Signing)
+    def signer(self):
+        return self._signer
+
+
+class OnDemandCredentials(
+        google.auth.credentials.Signing,
+        google.auth.credentials.Credentials):
+    """On-demand JWT credentials.
+
+    Like :class:`Credentials`, this class uses a JWT as the bearer token for
+    authentication. However, this class does not require the audience at
+    construction time. Instead, it will generate a new token on-demand for
+    each request using the request URI as the audience. It caches tokens
+    so that multiple requests to the same URI do not incur the overhead
+    of generating a new token every time.
+
+    This behavior is especially useful for `gRPC`_ clients. A gRPC service may
+    have multiple audience and gRPC clients may not know all of the audiences
+    required for accessing a particular service. With these credentials,
+    no knowledge of the audiences is required ahead of time.
+
+    .. _grpc: http://www.grpc.io/
+    """
+
+    def __init__(self, signer, issuer, subject,
+                 additional_claims=None,
+                 token_lifetime=_DEFAULT_TOKEN_LIFETIME_SECS,
+                 max_cache_size=_DEFAULT_MAX_CACHE_SIZE):
+        """
+        Args:
+            signer (google.auth.crypt.Signer): The signer used to sign JWTs.
+            issuer (str): The `iss` claim.
+            subject (str): The `sub` claim.
+            additional_claims (Mapping[str, str]): Any additional claims for
+                the JWT payload.
+            token_lifetime (int): The amount of time in seconds for
+                which the token is valid. Defaults to 1 hour.
+            max_cache_size (int): The maximum number of JWT tokens to keep in
+                cache. Tokens are cached using :class:`cachetools.LRUCache`.
+        """
+        super(OnDemandCredentials, self).__init__()
+        self._signer = signer
+        self._issuer = issuer
+        self._subject = subject
+        self._token_lifetime = token_lifetime
+
+        if additional_claims is None:
+            additional_claims = {}
+
+        self._additional_claims = additional_claims
+        self._cache = cachetools.LRUCache(maxsize=max_cache_size)
+
+    @classmethod
+    def _from_signer_and_info(cls, signer, info, **kwargs):
+        """Creates an OnDemandCredentials instance from a signer and service
+        account info.
+
+        Args:
+            signer (google.auth.crypt.Signer): The signer used to sign JWTs.
+            info (Mapping[str, str]): The service account info.
+            kwargs: Additional arguments to pass to the constructor.
+
+        Returns:
+            google.auth.jwt.OnDemandCredentials: The constructed credentials.
+
+        Raises:
+            ValueError: If the info is not in the expected format.
+        """
+        kwargs.setdefault('subject', info['client_email'])
+        kwargs.setdefault('issuer', info['client_email'])
+        return cls(signer, **kwargs)
+
+    @classmethod
+    def from_service_account_info(cls, info, **kwargs):
+        """Creates an OnDemandCredentials instance from a dictionary.
+
+        Args:
+            info (Mapping[str, str]): The service account info in Google
+                format.
+            kwargs: Additional arguments to pass to the constructor.
+
+        Returns:
+            google.auth.jwt.OnDemandCredentials: The constructed credentials.
+
+        Raises:
+            ValueError: If the info is not in the expected format.
+        """
+        signer = _service_account_info.from_dict(
+            info, require=['client_email'])
+        return cls._from_signer_and_info(signer, info, **kwargs)
+
+    @classmethod
+    def from_service_account_file(cls, filename, **kwargs):
+        """Creates an OnDemandCredentials instance from a service account .json
+        file in Google format.
+
+        Args:
+            filename (str): The path to the service account .json file.
+            kwargs: Additional arguments to pass to the constructor.
+
+        Returns:
+            google.auth.jwt.OnDemandCredentials: The constructed credentials.
+        """
+        info, signer = _service_account_info.from_filename(
+            filename, require=['client_email'])
+        return cls._from_signer_and_info(signer, info, **kwargs)
+
+    @classmethod
+    def from_signing_credentials(cls, credentials, **kwargs):
+        """Creates a new :class:`google.auth.jwt.OnDemandCredentials` instance
+        from an existing :class:`google.auth.credentials.Signing` instance.
+
+        The new instance will use the same signer as the existing instance and
+        will use the existing instance's signer email as the issuer and
+        subject by default.
+
+        Example::
+
+            svc_creds = service_account.Credentials.from_service_account_file(
+                'service_account.json')
+            jwt_creds = jwt.OnDemandCredentials.from_signing_credentials(
+                svc_creds)
+
+        Args:
+            credentials (google.auth.credentials.Signing): The credentials to
+                use to construct the new credentials.
+            kwargs: Additional arguments to pass to the constructor.
+
+        Returns:
+            google.auth.jwt.Credentials: A new Credentials instance.
+        """
+        kwargs.setdefault('issuer', credentials.signer_email)
+        kwargs.setdefault('subject', credentials.signer_email)
+        return cls(credentials.signer, **kwargs)
+
+    def with_claims(self, issuer=None, subject=None, additional_claims=None):
+        """Returns a copy of these credentials with modified claims.
+
+        Args:
+            issuer (str): The `iss` claim. If unspecified the current issuer
+                claim will be used.
+            subject (str): The `sub` claim. If unspecified the current subject
+                claim will be used.
+            additional_claims (Mapping[str, str]): Any additional claims for
+                the JWT payload. This will be merged with the current
+                additional claims.
+
+        Returns:
+            google.auth.jwt.OnDemandCredentials: A new credentials instance.
+        """
+        new_additional_claims = copy.deepcopy(self._additional_claims)
+        new_additional_claims.update(additional_claims or {})
+
+        return OnDemandCredentials(
+            self._signer,
+            issuer=issuer if issuer is not None else self._issuer,
+            subject=subject if subject is not None else self._subject,
+            additional_claims=new_additional_claims,
+            max_cache_size=self._cache.maxsize)
+
+    @property
+    def valid(self):
+        """Checks the validity of the credentials.
+
+        These credentials are always valid because it generates tokens on
+        demand.
+        """
+        return True
+
+    def _make_jwt_for_audience(self, audience):
+        """Make a new JWT for the given audience.
+
+        Args:
+            audience (str): The intended audience.
+
+        Returns:
+            Tuple[bytes, datetime]: The encoded JWT and the expiration.
+        """
+        now = _helpers.utcnow()
+        lifetime = datetime.timedelta(seconds=self._token_lifetime)
+        expiry = now + lifetime
+
+        payload = {
+            'iss': self._issuer,
+            'sub': self._subject,
+            'iat': _helpers.datetime_to_secs(now),
+            'exp': _helpers.datetime_to_secs(expiry),
+            'aud': audience,
+        }
+
+        payload.update(self._additional_claims)
+
+        jwt = encode(self._signer, payload)
+
+        return jwt, expiry
+
+    def _get_jwt_for_audience(self, audience):
+        """Get a JWT For a given audience.
+
+        If there is already an existing, non-expired token in the cache for
+        the audience, that token is used. Otherwise, a new token will be
+        created.
+
+        Args:
+            audience (str): The intended audience.
+
+        Returns:
+            bytes: The encoded JWT.
+        """
+        token, expiry = self._cache.get(audience, (None, None))
+
+        if token is None or expiry < _helpers.utcnow():
+            token, expiry = self._make_jwt_for_audience(audience)
+            self._cache[audience] = token, expiry
+
+        return token
+
+    def refresh(self, request):
+        """Raises an exception, these credentials can not be directly
+        refreshed.
+
+        Args:
+            request (Any): Unused.
+
+        Raises:
+            google.auth.RefreshError
+        """
+        # pylint: disable=unused-argument
+        # (pylint doesn't correctly recognize overridden methods.)
+        raise exceptions.RefreshError(
+            'OnDemandCredentials can not be directly refreshed.')
+
+    def before_request(self, request, method, url, headers):
+        """Performs credential-specific before request logic.
+
+        Args:
+            request (Any): Unused. JWT credentials do not need to make an
+                HTTP request to refresh.
+            method (str): The request's HTTP method.
+            url (str): The request's URI. This is used as the audience claim
+                when generating the JWT.
+            headers (Mapping): The request's headers.
+        """
+        # pylint: disable=unused-argument
+        # (pylint doesn't correctly recognize overridden methods.)
+        parts = urllib.parse.urlsplit(url)
+        # Strip query string and fragment
+        audience = urllib.parse.urlunsplit(
+            (parts.scheme, parts.netloc, parts.path, None, None))
+        token = self._get_jwt_for_audience(audience)
+        self.apply(headers, token=token)
+
+    @_helpers.copy_docstring(google.auth.credentials.Signing)
+    def sign_bytes(self, message):
+        return self._signer.sign(message)
+
+    @property
+    @_helpers.copy_docstring(google.auth.credentials.Signing)
+    def signer_email(self):
+        return self._issuer
+
+    @property
+    @_helpers.copy_docstring(google.auth.credentials.Signing)
+    def signer(self):
+        return self._signer