__init__.py

"""Support for exposing Home Assistant via Zeroconf."""
from __future__ import annotations

import asyncio
import contextlib
from contextlib import suppress
from dataclasses import dataclass
from fnmatch import translate
from functools import lru_cache
from ipaddress import IPv4Address, IPv6Address
import logging
import re
import sys
from typing import Any, Final, cast

import voluptuous as vol
from zeroconf import (
    BadTypeInNameException,
    InterfaceChoice,
    IPVersion,
    ServiceStateChange,
)
from zeroconf.asyncio import AsyncServiceInfo

from homeassistant import config_entries
from homeassistant.components import network
from homeassistant.const import EVENT_HOMEASSISTANT_STOP, __version__
from homeassistant.core import Event, HomeAssistant, callback
from homeassistant.data_entry_flow import BaseServiceInfo
from homeassistant.helpers import discovery_flow, instance_id
import homeassistant.helpers.config_validation as cv
from homeassistant.helpers.network import NoURLAvailableError, get_url
from homeassistant.helpers.typing import ConfigType
from homeassistant.loader import (
    HomeKitDiscoveredIntegration,
    async_get_homekit,
    async_get_zeroconf,
    bind_hass,
)
from homeassistant.setup import async_when_setup_or_start

from .models import HaAsyncServiceBrowser, HaAsyncZeroconf, HaZeroconf
from .usage import install_multiple_zeroconf_catcher

_LOGGER = logging.getLogger(__name__)

DOMAIN = "zeroconf"

ZEROCONF_TYPE = "_home-assistant._tcp.local."
HOMEKIT_TYPES = [
    "_hap._tcp.local.",
    # Thread based devices
    "_hap._udp.local.",
]
_HOMEKIT_MODEL_SPLITS = (None, " ", "-")

# Top level keys we support matching against in properties that are always matched in
# lower case. ex: ZeroconfServiceInfo.name
LOWER_MATCH_ATTRS = {"name"}

CONF_DEFAULT_INTERFACE = "default_interface"
CONF_IPV6 = "ipv6"
DEFAULT_DEFAULT_INTERFACE = True
DEFAULT_IPV6 = True

HOMEKIT_PAIRED_STATUS_FLAG = "sf"
HOMEKIT_MODEL_LOWER = "md"
HOMEKIT_MODEL_UPPER = "MD"

# Property key=value has a max length of 255
# so we use 230 to leave space for key=
MAX_PROPERTY_VALUE_LEN = 230

# Dns label max length
MAX_NAME_LEN = 63

ATTR_PROPERTIES: Final = "properties"

# Attributes for ZeroconfServiceInfo[ATTR_PROPERTIES]
ATTR_PROPERTIES_ID: Final = "id"

CONFIG_SCHEMA = vol.Schema(
    {
        DOMAIN: vol.All(
            cv.deprecated(CONF_DEFAULT_INTERFACE),
            cv.deprecated(CONF_IPV6),
            vol.Schema(
                {
                    vol.Optional(CONF_DEFAULT_INTERFACE): cv.boolean,
                    vol.Optional(CONF_IPV6, default=DEFAULT_IPV6): cv.boolean,
                }
            ),
        )
    },
    extra=vol.ALLOW_EXTRA,
)


@dataclass(slots=True)
class ZeroconfServiceInfo(BaseServiceInfo):
    """Prepared info from mDNS entries."""

    host: str
    addresses: list[str]
    port: int | None
    hostname: str
    type: str
    name: str
    properties: dict[str, Any]


@bind_hass
async def async_get_instance(hass: HomeAssistant) -> HaZeroconf:
    """Zeroconf instance to be shared with other integrations that use it."""
    return cast(HaZeroconf, (await _async_get_instance(hass)).zeroconf)


@bind_hass
async def async_get_async_instance(hass: HomeAssistant) -> HaAsyncZeroconf:
    """Zeroconf instance to be shared with other integrations that use it."""
    return await _async_get_instance(hass)


async def _async_get_instance(hass: HomeAssistant, **zcargs: Any) -> HaAsyncZeroconf:
    if DOMAIN in hass.data:
        return cast(HaAsyncZeroconf, hass.data[DOMAIN])

    logging.getLogger("zeroconf").setLevel(logging.NOTSET)

    zeroconf = HaZeroconf(**zcargs)
    aio_zc = HaAsyncZeroconf(zc=zeroconf)

    install_multiple_zeroconf_catcher(zeroconf)

    async def _async_stop_zeroconf(_event: Event) -> None:
        """Stop Zeroconf."""
        await aio_zc.ha_async_close()

    hass.bus.async_listen_once(EVENT_HOMEASSISTANT_STOP, _async_stop_zeroconf)
    hass.data[DOMAIN] = aio_zc

    return aio_zc


@callback
def _async_zc_has_functional_dual_stack() -> bool:
    """Return true for platforms not supporting IP_ADD_MEMBERSHIP on an AF_INET6 socket.

    Zeroconf only supports a single listen socket at this time.
    """
    return not sys.platform.startswith("freebsd") and not sys.platform.startswith(
        "darwin"
    )


async def async_setup(hass: HomeAssistant, config: ConfigType) -> bool:
    """Set up Zeroconf and make Home Assistant discoverable."""
    zc_args: dict = {"ip_version": IPVersion.V4Only}

    adapters = await network.async_get_adapters(hass)

    ipv6 = False
    if _async_zc_has_functional_dual_stack():
        if any(adapter["enabled"] and adapter["ipv6"] for adapter in adapters):
            ipv6 = True
            zc_args["ip_version"] = IPVersion.All
    elif not any(adapter["enabled"] and adapter["ipv4"] for adapter in adapters):
        zc_args["ip_version"] = IPVersion.V6Only
        ipv6 = True

    if not ipv6 and network.async_only_default_interface_enabled(adapters):
        zc_args["interfaces"] = InterfaceChoice.Default
    else:
        zc_args["interfaces"] = [
            str(source_ip)
            for source_ip in await network.async_get_enabled_source_ips(hass)
            if not source_ip.is_loopback
            and not (isinstance(source_ip, IPv6Address) and source_ip.is_global)
            and not (
                isinstance(source_ip, IPv6Address)
                and zc_args["ip_version"] == IPVersion.V4Only
            )
            and not (
                isinstance(source_ip, IPv4Address)
                and zc_args["ip_version"] == IPVersion.V6Only
            )
        ]

    aio_zc = await _async_get_instance(hass, **zc_args)
    zeroconf = cast(HaZeroconf, aio_zc.zeroconf)
    zeroconf_types, homekit_models = await asyncio.gather(
        async_get_zeroconf(hass), async_get_homekit(hass)
    )
    homekit_model_lookup, homekit_model_matchers = _build_homekit_model_lookups(
        homekit_models
    )
    discovery = ZeroconfDiscovery(
        hass,
        zeroconf,
        zeroconf_types,
        homekit_model_lookup,
        homekit_model_matchers,
        ipv6,
    )
    await discovery.async_setup()

    async def _async_zeroconf_hass_start(hass: HomeAssistant, comp: str) -> None:
        """Expose Home Assistant on zeroconf when it starts.

        Wait till started or otherwise HTTP is not up and running.
        """
        uuid = await instance_id.async_get(hass)
        await _async_register_hass_zc_service(hass, aio_zc, uuid)

    async def _async_zeroconf_hass_stop(_event: Event) -> None:
        await discovery.async_stop()

    hass.bus.async_listen_once(EVENT_HOMEASSISTANT_STOP, _async_zeroconf_hass_stop)
    async_when_setup_or_start(hass, "frontend", _async_zeroconf_hass_start)

    return True


def _build_homekit_model_lookups(
    homekit_models: dict[str, HomeKitDiscoveredIntegration]
) -> tuple[
    dict[str, HomeKitDiscoveredIntegration],
    dict[re.Pattern, HomeKitDiscoveredIntegration],
]:
    """Build lookups for homekit models."""
    homekit_model_lookup: dict[str, HomeKitDiscoveredIntegration] = {}
    homekit_model_matchers: dict[re.Pattern, HomeKitDiscoveredIntegration] = {}

    for model, discovery in homekit_models.items():
        if "*" in model or "?" in model or "[" in model:
            homekit_model_matchers[_compile_fnmatch(model)] = discovery
        else:
            homekit_model_lookup[model] = discovery

    return homekit_model_lookup, homekit_model_matchers


def _filter_disallowed_characters(name: str) -> str:
    """Filter disallowed characters from a string.

    . is a reversed character for zeroconf.
    """
    return name.replace(".", " ")


async def _async_register_hass_zc_service(
    hass: HomeAssistant, aio_zc: HaAsyncZeroconf, uuid: str
) -> None:
    # Get instance UUID
    valid_location_name = _truncate_location_name_to_valid(
        _filter_disallowed_characters(hass.config.location_name or "Home")
    )

    params = {
        "location_name": valid_location_name,
        "uuid": uuid,
        "version": __version__,
        "external_url": "",
        "internal_url": "",
        # Old base URL, for backward compatibility
        "base_url": "",
        # Always needs authentication
        "requires_api_password": True,
    }

    # Get instance URL's
    with suppress(NoURLAvailableError):
        params["external_url"] = get_url(hass, allow_internal=False)

    with suppress(NoURLAvailableError):
        params["internal_url"] = get_url(hass, allow_external=False)

    # Set old base URL based on external or internal
    params["base_url"] = params["external_url"] or params["internal_url"]

    _suppress_invalid_properties(params)

    info = AsyncServiceInfo(
        ZEROCONF_TYPE,
        name=f"{valid_location_name}.{ZEROCONF_TYPE}",
        server=f"{uuid}.local.",
        parsed_addresses=await network.async_get_announce_addresses(hass),
        port=hass.http.server_port,
        properties=params,
    )

    _LOGGER.info("Starting Zeroconf broadcast")
    await aio_zc.async_register_service(info, allow_name_change=True)


def _match_against_data(
    matcher: dict[str, str | dict[str, str]], match_data: dict[str, str]
) -> bool:
    """Check a matcher to ensure all values in match_data match."""
    for key in LOWER_MATCH_ATTRS:
        if key not in matcher:
            continue
        if key not in match_data:
            return False
        match_val = matcher[key]
        assert isinstance(match_val, str)

        if not _memorized_fnmatch(match_data[key], match_val):
            return False
    return True


def _match_against_props(matcher: dict[str, str], props: dict[str, str]) -> bool:
    """Check a matcher to ensure all values in props."""
    return not any(
        key
        for key in matcher
        if key not in props or not _memorized_fnmatch(props[key].lower(), matcher[key])
    )


def is_homekit_paired(props: dict[str, Any]) -> bool:
    """Check properties to see if a device is homekit paired."""
    if HOMEKIT_PAIRED_STATUS_FLAG not in props:
        return False
    with contextlib.suppress(ValueError):
        # 0 means paired and not discoverable by iOS clients)
        return int(props[HOMEKIT_PAIRED_STATUS_FLAG]) == 0
    # If we cannot tell, we assume its not paired
    return False


class ZeroconfDiscovery:
    """Discovery via zeroconf."""

    def __init__(
        self,
        hass: HomeAssistant,
        zeroconf: HaZeroconf,
        zeroconf_types: dict[str, list[dict[str, str | dict[str, str]]]],
        homekit_model_lookups: dict[str, HomeKitDiscoveredIntegration],
        homekit_model_matchers: dict[re.Pattern, HomeKitDiscoveredIntegration],
        ipv6: bool,
    ) -> None:
        """Init discovery."""
        self.hass = hass
        self.zeroconf = zeroconf
        self.zeroconf_types = zeroconf_types
        self.homekit_model_lookups = homekit_model_lookups
        self.homekit_model_matchers = homekit_model_matchers

        self.ipv6 = ipv6

        self.async_service_browser: HaAsyncServiceBrowser | None = None

    async def async_setup(self) -> None:
        """Start discovery."""
        types = list(self.zeroconf_types)
        # We want to make sure we know about other HomeAssistant
        # instances as soon as possible to avoid name conflicts
        # so we always browse for ZEROCONF_TYPE
        for hk_type in (ZEROCONF_TYPE, *HOMEKIT_TYPES):
            if hk_type not in self.zeroconf_types:
                types.append(hk_type)
        _LOGGER.debug("Starting Zeroconf browser for: %s", types)
        self.async_service_browser = HaAsyncServiceBrowser(
            self.ipv6, self.zeroconf, types, handlers=[self.async_service_update]
        )

    async def async_stop(self) -> None:
        """Cancel the service browser and stop processing the queue."""
        if self.async_service_browser:
            await self.async_service_browser.async_cancel()

    def _async_dismiss_discoveries(self, name: str) -> None:
        """Dismiss all discoveries for the given name."""
        for flow in self.hass.config_entries.flow.async_progress_by_init_data_type(
            ZeroconfServiceInfo,
            lambda service_info: bool(service_info.name == name),
        ):
            self.hass.config_entries.flow.async_abort(flow["flow_id"])

    @callback
    def async_service_update(
        self,
        zeroconf: HaZeroconf,
        service_type: str,
        name: str,
        state_change: ServiceStateChange,
    ) -> None:
        """Service state changed."""
        _LOGGER.debug(
            "service_update: type=%s name=%s state_change=%s",
            service_type,
            name,
            state_change,
        )

        if state_change == ServiceStateChange.Removed:
            self._async_dismiss_discoveries(name)
            return

        try:
            async_service_info = AsyncServiceInfo(service_type, name)
        except BadTypeInNameException as ex:
            # Some devices broadcast a name that is not a valid DNS name
            # This is a bug in the device firmware and we should ignore it
            _LOGGER.debug("Bad name in zeroconf record: %s: %s", name, ex)
            return

        if async_service_info.load_from_cache(zeroconf):
            self._async_process_service_update(async_service_info, service_type, name)
        else:
            self.hass.async_create_task(
                self._async_lookup_and_process_service_update(
                    zeroconf, async_service_info, service_type, name
                )
            )

    async def _async_lookup_and_process_service_update(
        self,
        zeroconf: HaZeroconf,
        async_service_info: AsyncServiceInfo,
        service_type: str,
        name: str,
    ) -> None:
        """Update and process a zeroconf update."""
        await async_service_info.async_request(zeroconf, 3000)
        self._async_process_service_update(async_service_info, service_type, name)

    @callback
    def _async_process_service_update(
        self, async_service_info: AsyncServiceInfo, service_type: str, name: str
    ) -> None:
        """Process a zeroconf update."""
        info = info_from_service(async_service_info)
        if not info:
            # Prevent the browser thread from collapsing
            _LOGGER.debug("Failed to get addresses for device %s", name)
            return
        _LOGGER.debug("Discovered new device %s %s", name, info)
        props: dict[str, str] = info.properties
        domain = None

        # If we can handle it as a HomeKit discovery, we do that here.
        if service_type in HOMEKIT_TYPES and (
            homekit_discovery := async_get_homekit_discovery(
                self.homekit_model_lookups, self.homekit_model_matchers, props
            )
        ):
            domain = homekit_discovery.domain
            discovery_flow.async_create_flow(
                self.hass,
                homekit_discovery.domain,
                {"source": config_entries.SOURCE_HOMEKIT},
                info,
            )
            # Continue on here as homekit_controller
            # still needs to get updates on devices
            # so it can see when the 'c#' field is updated.
            #
            # We only send updates to homekit_controller
            # if the device is already paired in order to avoid
            # offering a second discovery for the same device
            if not is_homekit_paired(props) and not homekit_discovery.always_discover:
                # If the device is paired with HomeKit we must send on
                # the update to homekit_controller so it can see when
                # the 'c#' field is updated. This is used to detect
                # when the device has been reset or updated.
                #
                # If the device is not paired and we should not always
                # discover it, we can stop here.
                return

        match_data: dict[str, str] = {}
        for key in LOWER_MATCH_ATTRS:
            attr_value: str = getattr(info, key)
            match_data[key] = attr_value.lower()

        # Not all homekit types are currently used for discovery
        # so not all service type exist in zeroconf_types
        for matcher in self.zeroconf_types.get(service_type, []):
            if len(matcher) > 1:
                if not _match_against_data(matcher, match_data):
                    continue
                if ATTR_PROPERTIES in matcher:
                    matcher_props = matcher[ATTR_PROPERTIES]
                    assert isinstance(matcher_props, dict)
                    if not _match_against_props(matcher_props, props):
                        continue

            matcher_domain = matcher["domain"]
            assert isinstance(matcher_domain, str)
            context = {
                "source": config_entries.SOURCE_ZEROCONF,
            }
            if domain:
                # Domain of integration that offers alternative API to handle
                # this device.
                context["alternative_domain"] = domain

            discovery_flow.async_create_flow(
                self.hass,
                matcher_domain,
                context,
                info,
            )


def async_get_homekit_discovery(
    homekit_model_lookups: dict[str, HomeKitDiscoveredIntegration],
    homekit_model_matchers: dict[re.Pattern, HomeKitDiscoveredIntegration],
    props: dict[str, Any],
) -> HomeKitDiscoveredIntegration | None:
    """Handle a HomeKit discovery.

    Return the domain to forward the discovery data to
    """
    if not (model := props.get(HOMEKIT_MODEL_LOWER) or props.get(HOMEKIT_MODEL_UPPER)):
        return None

    assert isinstance(model, str)

    for split_str in _HOMEKIT_MODEL_SPLITS:
        key = (model.split(split_str))[0] if split_str else model
        if discovery := homekit_model_lookups.get(key):
            return discovery

    for pattern, discovery in homekit_model_matchers.items():
        if pattern.match(model):
            return discovery

    return None


@lru_cache(maxsize=256)  # matches to the cache in zeroconf itself
def _stringify_ip_address(ip_addr: IPv4Address | IPv6Address) -> str:
    """Stringify an IP address."""
    return str(ip_addr)


def info_from_service(service: AsyncServiceInfo) -> ZeroconfServiceInfo | None:
    """Return prepared info from mDNS entries."""
    # See https://ietf.org/rfc/rfc6763.html#section-6.4 and
    # https://ietf.org/rfc/rfc6763.html#section-6.5 for expected encodings
    # for property keys and values
    if not (ip_addresses := service.ip_addresses_by_version(IPVersion.All)):
        return None
    host: str | None = None
    for ip_addr in ip_addresses:
        if not ip_addr.is_link_local and not ip_addr.is_unspecified:
            host = _stringify_ip_address(ip_addr)
            break
    if not host:
        return None
    properties: dict[str, Any] = {
        k.decode("ascii", "replace"): None
        if v is None
        else v.decode("utf-8", "replace")
        for k, v in service.properties.items()
    }

    assert service.server is not None, "server cannot be none if there are addresses"
    return ZeroconfServiceInfo(
        host=host,
        addresses=[_stringify_ip_address(ip_addr) for ip_addr in ip_addresses],
        port=service.port,
        hostname=service.server,
        type=service.type,
        name=service.name,
        properties=properties,
    )


def _suppress_invalid_properties(properties: dict) -> None:
    """Suppress any properties that will cause zeroconf to fail to startup."""

    for prop, prop_value in properties.items():
        if not isinstance(prop_value, str):
            continue

        if len(prop_value.encode("utf-8")) > MAX_PROPERTY_VALUE_LEN:
            _LOGGER.error(
                (
                    "The property '%s' was suppressed because it is longer than the"
                    " maximum length of %d bytes: %s"
                ),
                prop,
                MAX_PROPERTY_VALUE_LEN,
                prop_value,
            )
            properties[prop] = ""


def _truncate_location_name_to_valid(location_name: str) -> str:
    """Truncate or return the location name usable for zeroconf."""
    if len(location_name.encode("utf-8")) < MAX_NAME_LEN:
        return location_name

    _LOGGER.warning(
        (
            "The location name was truncated because it is longer than the maximum"
            " length of %d bytes: %s"
        ),
        MAX_NAME_LEN,
        location_name,
    )
    return location_name.encode("utf-8")[:MAX_NAME_LEN].decode("utf-8", "ignore")


@lru_cache(maxsize=4096, typed=True)
def _compile_fnmatch(pattern: str) -> re.Pattern:
    """Compile a fnmatch pattern."""
    return re.compile(translate(pattern))


@lru_cache(maxsize=1024, typed=True)
def _memorized_fnmatch(name: str, pattern: str) -> bool:
    """Memorized version of fnmatch that has a larger lru_cache.

    The default version of fnmatch only has a lru_cache of 256 entries.
    With many devices we quickly reach that limit and end up compiling
    the same pattern over and over again.

    Zeroconf has its own memorized fnmatch with its own lru_cache
    since the data is going to be relatively the same
    since the devices will not change frequently
    """
    return bool(_compile_fnmatch(pattern).match(name))