csrf.py 文件源码

def validate_csrf(data, secret_key=None, time_limit=None, token_key=None):
    """Check if the given data is a valid CSRF token. This compares the given
    signed token to the one stored in the session.

    :param data: The signed CSRF token to be checked.
    :param secret_key: Used to securely sign the token. Default is
        ``WTF_CSRF_SECRET_KEY`` or ``SECRET_KEY``.
    :param time_limit: Number of seconds that the token is valid. Default is
        ``WTF_CSRF_TIME_LIMIT`` or 3600 seconds (60 minutes).
    :param token_key: Key where token is stored in session for comparision.
        Default is ``WTF_CSRF_FIELD_NAME`` or ``'csrf_token'``.

    :raises ValidationError: Contains the reason that validation failed.

    .. versionchanged:: 0.14
        Raises ``ValidationError`` with a specific error message rather than
        returning ``True`` or ``False``.
    """

    secret_key = _get_config(
        secret_key, 'WTF_CSRF_SECRET_KEY', current_app.secret_key,
        message='A secret key is required to use CSRF.'
    )
    field_name = _get_config(
        token_key, 'WTF_CSRF_FIELD_NAME', 'csrf_token',
        message='A field name is required to use CSRF.'
    )
    time_limit = _get_config(
        time_limit, 'WTF_CSRF_TIME_LIMIT', 3600, required=False
    )

    if not data:
        raise ValidationError('The CSRF token is missing.')

    if field_name not in session:
        raise ValidationError('The CSRF session token is missing.')

    s = URLSafeTimedSerializer(secret_key, salt='wtf-csrf-token')

    try:
        token = s.loads(data, max_age=time_limit)
    except SignatureExpired:
        raise ValidationError('The CSRF token has expired.')
    except BadData:
        raise ValidationError('The CSRF token is invalid.')

    if not safe_str_cmp(session[field_name], token):
        raise ValidationError('The CSRF tokens do not match.')