auth.py

import os
import json
import webbrowser
import httplib2
import oauth2client.clientsecrets as clientsecrets
import threading

from googleapiclient.discovery import build
from functools import wraps
from oauth2client.service_account import ServiceAccountCredentials
from oauth2client.client import FlowExchangeError
from oauth2client.client import AccessTokenRefreshError
from oauth2client.client import OAuth2WebServerFlow
from oauth2client.client import OOB_CALLBACK_URN
from oauth2client.contrib.dictionary_storage import DictionaryStorage
from oauth2client.file import Storage
from oauth2client.tools import ClientRedirectHandler
from oauth2client.tools import ClientRedirectServer
from oauth2client._helpers import scopes_to_string
from .apiattr import ApiAttribute
from .apiattr import ApiAttributeMixin
from .settings import LoadSettingsFile
from .settings import ValidateSettings
from .settings import SettingsError
from .settings import InvalidConfigError


class AuthError(Exception):
    """Base error for authentication/authorization errors."""


class InvalidCredentialsError(IOError):
    """Error trying to read credentials file."""


class AuthenticationRejected(AuthError):
    """User rejected authentication."""


class AuthenticationError(AuthError):
    """General authentication error."""


class RefreshError(AuthError):
    """Access token refresh error."""


def LoadAuth(decoratee):
    """Decorator to check if the auth is valid and loads auth if not."""

    @wraps(decoratee)
    def _decorated(self, *args, **kwargs):
        # Initialize auth if needed.
        if self.auth is None:
            self.auth = GoogleAuth()
        # Re-create access token if it expired.
        if self.auth.access_token_expired:
            if getattr(self.auth, "auth_method", False) == "service":
                self.auth.ServiceAuth()
            else:
                self.auth.LocalWebserverAuth()

        # Initialise service if not built yet.
        if self.auth.service is None:
            self.auth.Authorize()

        # Ensure that a thread-safe HTTP object is provided.
        if (
            kwargs is not None
            and "param" in kwargs
            and kwargs["param"] is not None
            and "http" in kwargs["param"]
            and kwargs["param"]["http"] is not None
        ):
            self.http = kwargs["param"]["http"]
            del kwargs["param"]["http"]

        else:
            # If HTTP object not specified, create or resuse an HTTP
            # object from the thread local storage.
            if not getattr(self.auth.thread_local, "http", None):
                self.auth.thread_local.http = self.auth.Get_Http_Object()
            self.http = self.auth.thread_local.http

        return decoratee(self, *args, **kwargs)

    return _decorated


def CheckServiceAuth(decoratee):
    """Decorator to authorize service account."""

    @wraps(decoratee)
    def _decorated(self, *args, **kwargs):
        self.auth_method = "service"
        dirty = False
        save_credentials = self.settings.get("save_credentials")
        if self.credentials is None and save_credentials:
            self.LoadCredentials()
        if self.credentials is None:
            decoratee(self, *args, **kwargs)
            self.Authorize()
            dirty = True
        elif self.access_token_expired:
            self.Refresh()
            dirty = True
        self.credentials.set_store(self._default_storage)
        if dirty and save_credentials:
            self.SaveCredentials()

    return _decorated


def CheckAuth(decoratee):
    """Decorator to check if it requires OAuth2 flow request."""

    @wraps(decoratee)
    def _decorated(self, *args, **kwargs):
        dirty = False
        code = None
        save_credentials = self.settings.get("save_credentials")
        if self.credentials is None and save_credentials:
            self.LoadCredentials()
        if self.flow is None:
            self.GetFlow()
        if self.credentials is None:
            code = decoratee(self, *args, **kwargs)
            dirty = True
        else:
            if self.access_token_expired:
                if self.credentials.refresh_token is not None:
                    self.Refresh()
                else:
                    code = decoratee(self, *args, **kwargs)
                dirty = True
        if code is not None:
            self.Auth(code)
        self.credentials.set_store(self._default_storage)
        if dirty and save_credentials:
            self.SaveCredentials()

    return _decorated


class GoogleAuth(ApiAttributeMixin):
    """Wrapper class for oauth2client library in google-api-python-client.

    Loads all settings and credentials from one 'settings.yaml' file
    and performs common OAuth2.0 related functionality such as authentication
    and authorization.
    """

    DEFAULT_SETTINGS = {
        "client_config_backend": "file",
        "client_config_file": "client_secrets.json",
        "save_credentials": False,
        "oauth_scope": ["https://www.googleapis.com/auth/drive"],
    }
    CLIENT_CONFIGS_LIST = [
        "client_id",
        "client_secret",
        "auth_uri",
        "token_uri",
        "revoke_uri",
        "redirect_uri",
    ]
    SERVICE_CONFIGS_LIST = ["client_user_email"]
    settings = ApiAttribute("settings")
    client_config = ApiAttribute("client_config")
    flow = ApiAttribute("flow")
    credentials = ApiAttribute("credentials")
    http = ApiAttribute("http")
    service = ApiAttribute("service")
    auth_method = ApiAttribute("auth_method")

    def __init__(
        self, settings_file="settings.yaml", http_timeout=None, settings=None
    ):
        """Create an instance of GoogleAuth.

        :param settings_file: path of settings file. 'settings.yaml' by default.
        :type settings_file: str.
        :param settings: settings dict.
        :type settings: dict.
        """
        self.http_timeout = http_timeout
        ApiAttributeMixin.__init__(self)
        self.thread_local = threading.local()
        self.client_config = {}

        if settings is None and settings_file:
            try:
                settings = LoadSettingsFile(settings_file)
            except SettingsError:
                pass

        self.settings = settings or self.DEFAULT_SETTINGS
        ValidateSettings(self.settings)

        storages, default = self._InitializeStoragesFromSettings()
        self._storages = storages
        self._default_storage = default

    @property
    def access_token_expired(self):
        """Checks if access token doesn't exist or is expired.

        :returns: bool -- True if access token doesn't exist or is expired.
        """
        if self.credentials is None:
            return True
        return self.credentials.access_token_expired

    @CheckAuth
    def LocalWebserverAuth(
        self,
        host_name="localhost",
        port_numbers=None,
        launch_browser=True,
        bind_addr=None,
    ):
        """Authenticate and authorize from user by creating local web server and
        retrieving authentication code.

        This function is not for web server application. It creates local web
        server for user from standalone application.

        If GDRIVE_NON_INTERACTIVE environment variable is set, this function
        raises AuthenticationError.

        :param host_name: host name of the local web server.
        :type host_name: str.
        :param port_numbers: list of port numbers to be tried to used.
        :type port_numbers: list.
        :param launch_browser: should browser be launched automatically
        :type launch_browser: bool
        :param bind_addr: optional IP address for the local web server to listen on.
            If not specified, it will listen on the address specified in the
            host_name parameter.
        :type bind_addr: str.
        :returns: str -- code returned from local web server
        :raises: AuthenticationRejected, AuthenticationError
        """
        if os.getenv("GDRIVE_NON_INTERACTIVE"):
            raise AuthenticationError(
                "Non interactive mode (GDRIVE_NON_INTERACTIVE env) is enabled"
            )

        if port_numbers is None:
            port_numbers = [
                8080,
                8090,
            ]  # Mutable objects should not be default
            # values, as each call's changes are global.
        success = False
        port_number = 0
        for port in port_numbers:
            port_number = port
            try:
                httpd = ClientRedirectServer(
                    (bind_addr or host_name, port), ClientRedirectHandler
                )
            except OSError:
                pass
            else:
                success = True
                break
        if success:
            oauth_callback = f"http://{host_name}:{port_number}/"
        else:
            print(
                "Failed to start a local web server. Please check your firewall"
            )
            print(
                "settings and locally running programs that may be blocking or"
            )
            print("using configured ports. Default ports are 8080 and 8090.")
            raise AuthenticationError()
        self.flow.redirect_uri = oauth_callback
        authorize_url = self.GetAuthUrl()
        if launch_browser:
            webbrowser.open(authorize_url, new=1, autoraise=True)
            print("Your browser has been opened to visit:")
        else:
            print("Open your browser to visit:")
        print()
        print("    " + authorize_url)
        print()
        httpd.handle_request()
        if "error" in httpd.query_params:
            print("Authentication request was rejected")
            raise AuthenticationRejected("User rejected authentication")
        if "code" in httpd.query_params:
            return httpd.query_params["code"]
        else:
            print(
                'Failed to find "code" in the query parameters of the redirect.'
            )
            print("Try command-line authentication")
            raise AuthenticationError("No code found in redirect")

    @CheckAuth
    def CommandLineAuth(self):
        """Authenticate and authorize from user by printing authentication url
        retrieving authentication code from command-line.

        :returns: str -- code returned from commandline.
        """
        self.flow.redirect_uri = OOB_CALLBACK_URN
        authorize_url = self.GetAuthUrl()
        print("Go to the following link in your browser:")
        print()
        print("    " + authorize_url)
        print()
        return input("Enter verification code: ").strip()

    @CheckServiceAuth
    def ServiceAuth(self):
        """Authenticate and authorize using P12 private key, client id
        and client email for a Service account.
        :raises: AuthError, InvalidConfigError
        """
        if set(self.SERVICE_CONFIGS_LIST) - set(self.client_config):
            self.LoadServiceConfigSettings()
        scopes = scopes_to_string(self.settings["oauth_scope"])
        keyfile_name = self.client_config.get("client_json_file_path")
        keyfile_dict = self.client_config.get("client_json_dict")
        keyfile_json = self.client_config.get("client_json")

        if not keyfile_dict and keyfile_json:
            # Compensating for missing ServiceAccountCredentials.from_json_keyfile
            keyfile_dict = json.loads(keyfile_json)

        if keyfile_dict:
            self.credentials = (
                ServiceAccountCredentials.from_json_keyfile_dict(
                    keyfile_dict=keyfile_dict, scopes=scopes
                )
            )
        elif keyfile_name:
            self.credentials = (
                ServiceAccountCredentials.from_json_keyfile_name(
                    filename=keyfile_name, scopes=scopes
                )
            )
        else:
            service_email = self.client_config["client_service_email"]
            file_path = self.client_config["client_pkcs12_file_path"]
            self.credentials = ServiceAccountCredentials.from_p12_keyfile(
                service_account_email=service_email,
                filename=file_path,
                scopes=scopes,
            )

        user_email = self.client_config.get("client_user_email")
        if user_email:
            self.credentials = self.credentials.create_delegated(
                sub=user_email
            )

    def _InitializeStoragesFromSettings(self):
        result = {"file": None, "dictionary": None}
        backend = self.settings.get("save_credentials_backend")
        save_credentials = self.settings.get("save_credentials")
        if backend == "file":
            credentials_file = self.settings.get("save_credentials_file")
            if credentials_file is None:
                raise InvalidConfigError(
                    "Please specify credentials file to read"
                )
            result[backend] = Storage(credentials_file)
        elif backend == "dictionary":
            creds_dict = self.settings.get("save_credentials_dict")
            if creds_dict is None:
                raise InvalidConfigError("Please specify credentials dict")

            creds_key = self.settings.get("save_credentials_key")
            if creds_key is None:
                raise InvalidConfigError("Please specify credentials key")

            result[backend] = DictionaryStorage(creds_dict, creds_key)
        elif save_credentials:
            raise InvalidConfigError(
                "Unknown save_credentials_backend: %s" % backend
            )
        return result, result.get(backend)

    def LoadCredentials(self, backend=None):
        """Loads credentials or create empty credentials if it doesn't exist.

        :param backend: target backend to save credential to.
        :type backend: str.
        :raises: InvalidConfigError
        """
        if backend is None:
            backend = self.settings.get("save_credentials_backend")
            if backend is None:
                raise InvalidConfigError("Please specify credential backend")
        if backend == "file":
            self.LoadCredentialsFile()
        elif backend == "dictionary":
            self._LoadCredentialsDictionary()
        else:
            raise InvalidConfigError("Unknown save_credentials_backend")

    def LoadCredentialsFile(self, credentials_file=None):
        """Loads credentials or create empty credentials if it doesn't exist.

        Loads credentials file from path in settings if not specified.

        :param credentials_file: path of credentials file to read.
        :type credentials_file: str.
        :raises: InvalidConfigError, InvalidCredentialsError
        """
        if credentials_file is None:
            self._default_storage = self._storages["file"]
            if self._default_storage is None:
                raise InvalidConfigError(
                    "Backend `file` is not configured, specify "
                    "credentials file to read in the settings "
                    "file or pass an explicit value"
                )
        else:
            self._default_storage = Storage(credentials_file)

        try:
            self.credentials = self._default_storage.get()
        except OSError:
            raise InvalidCredentialsError(
                "Credentials file cannot be symbolic link"
            )

        if self.credentials:
            self.credentials.set_store(self._default_storage)

    def _LoadCredentialsDictionary(self):
        self._default_storage = self._storages["dictionary"]
        if self._default_storage is None:
            raise InvalidConfigError(
                "Backend `dictionary` is not configured, specify "
                "credentials dict and key to read in the settings file"
            )

        self.credentials = self._default_storage.get()

        if self.credentials:
            self.credentials.set_store(self._default_storage)

    def SaveCredentials(self, backend=None):
        """Saves credentials according to specified backend.

        If you have any specific credentials backend in mind, don't use this
        function and use the corresponding function you want.

        :param backend: backend to save credentials.
        :type backend: str.
        :raises: InvalidConfigError
        """
        if backend is None:
            backend = self.settings.get("save_credentials_backend")
            if backend is None:
                raise InvalidConfigError("Please specify credential backend")
        if backend == "file":
            self.SaveCredentialsFile()
        elif backend == "dictionary":
            self._SaveCredentialsDictionary()
        else:
            raise InvalidConfigError("Unknown save_credentials_backend")

    def SaveCredentialsFile(self, credentials_file=None):
        """Saves credentials to the file in JSON format.

        :param credentials_file: destination to save file to.
        :type credentials_file: str.
        :raises: InvalidConfigError, InvalidCredentialsError
        """
        if self.credentials is None:
            raise InvalidCredentialsError("No credentials to save")

        if credentials_file is None:
            storage = self._storages["file"]
            if storage is None:
                raise InvalidConfigError(
                    "Backend `file` is not configured, specify "
                    "credentials file to read in the settings "
                    "file or pass an explicit value"
                )
        else:
            storage = Storage(credentials_file)

        try:
            storage.put(self.credentials)
        except OSError:
            raise InvalidCredentialsError(
                "Credentials file cannot be symbolic link"
            )

    def _SaveCredentialsDictionary(self):
        if self.credentials is None:
            raise InvalidCredentialsError("No credentials to save")

        storage = self._storages["dictionary"]
        if storage is None:
            raise InvalidConfigError(
                "Backend `dictionary` is not configured, specify "
                "credentials dict and key to write in the settings file"
            )

        storage.put(self.credentials)

    def LoadClientConfig(self, backend=None):
        """Loads client configuration according to specified backend.

        If you have any specific backend to load client configuration from in mind,
        don't use this function and use the corresponding function you want.

        :param backend: backend to load client configuration from.
        :type backend: str.
        :raises: InvalidConfigError
        """
        if backend is None:
            backend = self.settings.get("client_config_backend")
            if backend is None:
                raise InvalidConfigError(
                    "Please specify client config backend"
                )
        if backend == "file":
            self.LoadClientConfigFile()
        elif backend == "settings":
            self.LoadClientConfigSettings()
        elif backend == "service":
            self.LoadServiceConfigSettings()
        else:
            raise InvalidConfigError("Unknown client_config_backend")

    def LoadClientConfigFile(self, client_config_file=None):
        """Loads client configuration file downloaded from APIs console.

        Loads client config file from path in settings if not specified.

        :param client_config_file: path of client config file to read.
        :type client_config_file: str.
        :raises: InvalidConfigError
        """
        if client_config_file is None:
            client_config_file = self.settings["client_config_file"]
        try:
            client_type, client_info = clientsecrets.loadfile(
                client_config_file
            )
        except clientsecrets.InvalidClientSecretsError as error:
            raise InvalidConfigError("Invalid client secrets file %s" % error)
        if client_type not in (
            clientsecrets.TYPE_WEB,
            clientsecrets.TYPE_INSTALLED,
        ):
            raise InvalidConfigError(
                "Unknown client_type of client config file"
            )

        # General settings.
        try:
            config_index = [
                "client_id",
                "client_secret",
                "auth_uri",
                "token_uri",
            ]
            for config in config_index:
                self.client_config[config] = client_info[config]

            self.client_config["revoke_uri"] = client_info.get("revoke_uri")
            self.client_config["redirect_uri"] = client_info["redirect_uris"][
                0
            ]
        except KeyError:
            raise InvalidConfigError("Insufficient client config in file")

        # Service auth related fields.
        service_auth_config = ["client_email"]
        try:
            for config in service_auth_config:
                self.client_config[config] = client_info[config]
        except KeyError:
            pass  # The service auth fields are not present, handling code can go here.

    def LoadServiceConfigSettings(self):
        """Loads client configuration from settings.
        :raises: InvalidConfigError
        """
        configs = [
            "client_json_file_path",
            "client_json_dict",
            "client_json",
            "client_pkcs12_file_path",
        ]

        for config in configs:
            value = self.settings["service_config"].get(config)
            if value:
                self.client_config[config] = value
                break
        else:
            raise InvalidConfigError(
                f"One of {configs} is required for service authentication"
            )

        if config == "client_pkcs12_file_path":
            self.SERVICE_CONFIGS_LIST.append("client_service_email")

        for config in self.SERVICE_CONFIGS_LIST:
            try:
                self.client_config[config] = self.settings["service_config"][
                    config
                ]
            except KeyError:
                err = "Insufficient service config in settings"
                err += f"\n\nMissing: {config} key."
                raise InvalidConfigError(err)

    def LoadClientConfigSettings(self):
        """Loads client configuration from settings file.

        :raises: InvalidConfigError
        """
        for config in self.CLIENT_CONFIGS_LIST:
            try:
                self.client_config[config] = self.settings["client_config"][
                    config
                ]
            except KeyError:
                raise InvalidConfigError(
                    "Insufficient client config in settings"
                )

    def GetFlow(self):
        """Gets Flow object from client configuration.

        :raises: InvalidConfigError
        """
        if not all(
            config in self.client_config for config in self.CLIENT_CONFIGS_LIST
        ):
            self.LoadClientConfig()
        constructor_kwargs = {
            "redirect_uri": self.client_config["redirect_uri"],
            "auth_uri": self.client_config["auth_uri"],
            "token_uri": self.client_config["token_uri"],
            "access_type": "online",
        }
        if self.client_config["revoke_uri"] is not None:
            constructor_kwargs["revoke_uri"] = self.client_config["revoke_uri"]
        self.flow = OAuth2WebServerFlow(
            self.client_config["client_id"],
            self.client_config["client_secret"],
            scopes_to_string(self.settings["oauth_scope"]),
            **constructor_kwargs,
        )
        if self.settings.get("get_refresh_token"):
            self.flow.params.update(
                {"access_type": "offline", "approval_prompt": "force"}
            )

    def Refresh(self):
        """Refreshes the access_token.

        :raises: RefreshError
        """
        if self.credentials is None:
            raise RefreshError("No credential to refresh.")
        if (
            self.credentials.refresh_token is None
            and self.auth_method != "service"
        ):
            raise RefreshError(
                "No refresh_token found."
                "Please set access_type of OAuth to offline."
            )
        if self.http is None:
            self.http = self._build_http()
        try:
            self.credentials.refresh(self.http)
        except AccessTokenRefreshError as error:
            raise RefreshError("Access token refresh failed: %s" % error)

    def GetAuthUrl(self):
        """Creates authentication url where user visits to grant access.

        :returns: str -- Authentication url.
        """
        if self.flow is None:
            self.GetFlow()
        return self.flow.step1_get_authorize_url()

    def Auth(self, code):
        """Authenticate, authorize, and build service.

        :param code: Code for authentication.
        :type code: str.
        :raises: AuthenticationError
        """
        self.Authenticate(code)
        self.Authorize()

    def Authenticate(self, code):
        """Authenticates given authentication code back from user.

        :param code: Code for authentication.
        :type code: str.
        :raises: AuthenticationError
        """
        if self.flow is None:
            self.GetFlow()
        try:
            self.credentials = self.flow.step2_exchange(code)
        except FlowExchangeError as e:
            raise AuthenticationError("OAuth2 code exchange failed: %s" % e)
        print("Authentication successful.")

    def _build_http(self):
        http = httplib2.Http(timeout=self.http_timeout)
        # 308's are used by several Google APIs (Drive, YouTube)
        # for Resumable Uploads rather than Permanent Redirects.
        # This asks httplib2 to exclude 308s from the status codes
        # it treats as redirects
        # See also: https://stackoverflow.com/a/59850170/298182
        try:
            http.redirect_codes = http.redirect_codes - {308}
        except AttributeError:
            # http.redirect_codes does not exist in previous versions
            # of httplib2, so pass
            pass
        return http

    def Authorize(self):
        """Authorizes and builds service.

        :raises: AuthenticationError
        """
        if self.access_token_expired:
            raise AuthenticationError(
                "No valid credentials provided to authorize"
            )

        if self.http is None:
            self.http = self._build_http()
        self.http = self.credentials.authorize(self.http)
        self.service = build(
            "drive", "v2", http=self.http, cache_discovery=False
        )

    def Get_Http_Object(self):
        """Create and authorize an httplib2.Http object. Necessary for
        thread-safety.
        :return: The http object to be used in each call.
        :rtype: httplib2.Http
        """
        http = self._build_http()
        http = self.credentials.authorize(http)
        return http