FreedomBox/plinth/modules/names/components.py

# SPDX-License-Identifier: AGPL-3.0-or-later
"""
App component to introduce a new domain type.
"""

from django.utils.translation import ugettext_lazy as _

from plinth import app

_SERVICES = {
    '__all__': {
        'display_name': _('All'),
        'port': None
    },
    'http': {
        'display_name': _('All web apps'),
        'port': 80
    },
    'https': {
        'display_name': _('All web apps'),
        'port': 443
    },
    'ssh': {
        'display_name': _('Secure Shell'),
        'port': 22
    },
}


class DomainType(app.FollowerComponent):
    """Component to create a new type of domain.

    It serves the primary purpose of showing a entry in the domain names page.
    This will allow users to discover the new type of domain and use the
    providing app to create that type of domain.

    Similar to a menu entry, domain type information is available to the user
    even when the corresponding app is disabled.

    """

    _all = {}

    def __init__(self, component_id, display_name, configuration_url,
                 can_have_certificate=True):
        """Initialize the domain type component.

        component_id should be a unique ID across all components of an app and
        across all components. This will also act as the 'type' parameter for
        each created domain.

        display_name is the type of domain displayed to the user in the
        interface.

        configuration_url is the Django URL to which a user is redirected to in
        order to create or manage a domain of this type.

        can_have_certificate indicates if this type of domain can have a TLS
        certificate that can be validated by a typical browser.

        """
        super().__init__(component_id)

        self.display_name = display_name
        self.configuration_url = configuration_url
        self.can_have_certificate = can_have_certificate

        self._all[component_id] = self

    @classmethod
    def get(cls, component_id):
        """Return a component of given ID."""
        return cls._all[component_id]

    @classmethod
    def list(cls):
        """Return a list of all domain types."""
        return dict(cls._all)


class DomainName(app.FollowerComponent):
    """Component to represent a domain name and its properties.

    Each domain name is necessarily attached to a domain type component that
    must be created prior to creating the domain name.

    When an application providing or managing a domain name is disabled, the
    corresponding domain name should become unavailable for others apps and
    they must de-configure the domain name from app configuration. This is the
    primary reason for making a domain name available as a component.

    """
    _all = {}

    def __init__(self, component_id, name, domain_type, services):
        """Initialize a domain name.

        component_id should be a unique ID across all components of an app and
        across all components. The value is typically 'domain-{app}-{domain}'.
        This ensures that if the same domain is managed by multiple apps, it is
        available as multiple instances. When one instance is removed, say by
        disabling that app, the other instance will still provide that domain.

        name is the domain name that is being represented by the component.
        This should be fully qualified domain name.

        domain_type should be a string representing the type of the domain.
        This is the component ID of the domain type earlier registered by the
        app that is creating the domain name component.

        services is a list of string identifiers for services potentially
        provided by the domain. For example, 'ssh' for secure shell service
        provided on port 22. It is used for showing information to the user and
        to retrieve a list of a domains that an app may use.

        A service value can also be an integer in which case it will be
        converted to a string by looking up a list of known services. This
        process is not perfect and may cause problems when filtering domains
        that could potentially provide a service.

        The most common value of a services parameter is the string '__all__'
        indicating that the domain can potentially provide any service without
        limitations due to the nature of the domain name.

        """
        super().__init__(component_id)

        self.name = name
        self.domain_type = DomainType.get(domain_type)
        self._services = DomainName._normalize_services(services)

        self._all[component_id] = self

    @property
    def services(self):
        """Read-only property to get the list of services."""
        return self._services

    @staticmethod
    def _normalize_services(services):
        """If ports numbers are provided convert them to service IDs."""
        if services == '__all__':
            return services

        return [DomainName._normalize_service(service) for service in services]

    @staticmethod
    def _normalize_service(service):
        """Return the service ID for a given port number.

        XXX: Eliminate this and use a generalized approach eventually.

        """
        if isinstance(service, str):
            return service

        if not isinstance(service, int):
            raise ValueError('Invalid service')

        for service_id, description in _SERVICES.items():
            if description['port'] == service:
                return service_id

        return str(service)

    def get_readable_services(self):
        """Return list of unique service strings that can be shown to user."""
        services = self.services
        if self.services == '__all__':
            services = [services]

        return {
            _SERVICES.get(service, {'display_name': service})['display_name']
            for service in services
        }

    def has_service(self, service):
        """Return whether a service is available for this domain name."""
        return (service is None or self.services == '__all__'
                or service in self.services)

    def remove(self):
        """Remove the domain name from global list of domains.

        It is acceptable to call remove() multiple times.

        """
        try:
            del self._all[self.component_id]
        except KeyError:
            pass

    @classmethod
    def get(cls, component_id):
        """Return the domain name object given name and app."""
        return cls._all[component_id]

    @classmethod
    def list(cls, filter_for_service=None):
        """Return list of domains."""
        return [
            domain for domain in cls._all.values()
            if domain.has_service(filter_for_service)
        ]

    @classmethod
    def list_names(cls, filter_for_service=None):
        """Return a set of unique domain names.

        Multiple different components may provide the same domain name. This
        method could be used to retrieve a list of all domain names without
        duplication.

        """
        return {
            domain.name
            for domain in cls._all.values()
            if domain.has_service(filter_for_service)
        }