authentication.py

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"""Implements authentication methods for the HTTP client."""
 
import json
import logging
import time
from enum import Enum
 
import requests
from requests.auth import HTTPBasicAuth
 
from aas_http_client.classes.Configuration.config_classes import OAuth
from aas_http_client.utilities.http_helper import log_response
 
_logger = logging.getLogger(__name__)
 
 
class AuthMethod(Enum):
    """Defines authentication methods.
 
    :param Enum: Base class for enumerations
    """
 
    No = 1
    basic_auth = 2
    o_auth = 3
    bearer = 4
 
 
class TokenData:
    """Holds token data."""
 
    def __init__(self, access_token: str, token_type: str, token_expiry: float):
        """Initializes the TokenData with the given parameters."""
        self.access_token: str = access_token
        self.token_type: str = token_type
        self.token_expiry: float = token_expiry
 
 
def get_token(o_auth_configuration: OAuth) -> TokenData | None:
    """Get token based on the provided OAuth configuration.
 
    :param auth_configuration: Authentication configuration
    :return: Access token or None if an error occurred
    """
    if o_auth_configuration.grant_type == "password":
        token = get_token_by_password(
            o_auth_configuration.token_url,
            o_auth_configuration.client_id,
            o_auth_configuration.get_client_secret(),
        )
 
    elif o_auth_configuration.is_active() and o_auth_configuration.grant_type == "client_credentials":
        token = get_token_by_basic_auth(
            o_auth_configuration.token_url,
            o_auth_configuration.client_id,
            o_auth_configuration.get_client_secret(),
        )
 
    if not token:
        _logger.error(f"Failed to receive token from endpoint '{o_auth_configuration.token_url}'")
        return None
 
    return token
 
 
def get_token_by_basic_auth(endpoint: str, username: str, password: str, timeout=200) -> TokenData | None:
    """Get token from a specific authentication service provider by basic authentication.
 
    :param endpoint: Get token endpoint for the authentication service provider
    :param username: Username for the authentication service provider
    :param password: Password for the authentication service provider
    :param timeout: Timeout for the API calls, defaults to 200
    :return: Access token or None if an error occurred
    """
    data = {"grant_type": "client_credentials"}
 
    auth = HTTPBasicAuth(username, password)
 
    return _get_token_from_endpoint(endpoint, data, auth, timeout)
 
 
def get_token_by_password(endpoint: str, username: str, password: str, timeout=200) -> TokenData | None:
    """Get token from a specific authentication service provider by username and password.
 
    :param endpoint: Get token endpoint for the authentication service provider
    :param username: Username for the authentication service provider
    :param password: Password for the authentication service provider
    :param timeout: Timeout for the API calls, defaults to 200
    :return: Access token or None if an error occurred
    """
    data = {"grant_type": "password", "username": username, "password": password}
 
    return _get_token_from_endpoint(endpoint, data, None, timeout)
 
 
def _get_token_from_endpoint(endpoint: str, data: dict[str, str], auth: HTTPBasicAuth | None = None, timeout: int = 200) -> TokenData | None:
    """Get token from a specific authentication service provider.
 
    :param endpoint: Get token endpoint for the authentication service provider
    :param data: Data for the authentication service provider
    :param timeout: Timeout for the API calls, defaults to 200
    :return: Access token or None if an error occurred
    """
    try:
        response = requests.post(endpoint, auth=auth, data=data, timeout=timeout)
        _logger.debug(f"Call REST API url '{response.url}'")
 
        if response.status_code != 200:
            log_response(response)
            return None
 
    except requests.exceptions.RequestException as e:
        _logger.error(f"Error call REST API: {e}")
        return None
 
    content = response.content.decode("utf-8")
 
    if not content:
        _logger.error("No content in token response")
        return None
 
    data = json.loads(content)
 
    if not data:
        _logger.error("No data in token response")
        return None
 
    access_token: str = data.get("access_token", "").strip()
    expires_in: int = int(data.get("expires_in", "0"))
    if not access_token or not expires_in:
        _logger.error("Invalid token data in response")
        return None
 
    token_type: str = data.get("token_type", "").strip()
    now: float = time.time()
    token_expiry: float = now + int(expires_in) - 60  # Subtract 60 seconds as buffer
 
    return TokenData(access_token=access_token, token_type=token_type, token_expiry=token_expiry)