Autodetect zeroconf interface selection when not set (#49529)

homeassistant/components/zeroconf/__init__.py

@@ -5,10 +5,12 @@ from contextlib import suppress
 import fnmatch
 from functools import partial
 import ipaddress
+from ipaddress import ip_address
 import logging
 import socket
-from typing import Any, TypedDict
+from typing import Any, Iterable, TypedDict, cast
 
+from pyroute2 import IPRoute
 import voluptuous as vol
 from zeroconf import (
     Error as ZeroconfError,
@@ -32,6 +34,7 @@ import homeassistant.helpers.config_validation as cv
 from homeassistant.helpers.network import NoURLAvailableError, get_url
 from homeassistant.helpers.singleton import singleton
 from homeassistant.loader import async_get_homekit, async_get_zeroconf
+from homeassistant.util.network import is_loopback
 
 from .models import HaServiceBrowser, HaZeroconf
 from .usage import install_multiple_zeroconf_catcher
@@ -55,6 +58,8 @@ DEFAULT_IPV6 = True
 HOMEKIT_PAIRED_STATUS_FLAG = "sf"
 HOMEKIT_MODEL = "md"
 
+MDNS_TARGET_IP = "224.0.0.251"
+
 # Property key=value has a max length of 255
 # so we use 230 to leave space for key=
 MAX_PROPERTY_VALUE_LEN = 230
@@ -66,9 +71,7 @@ CONFIG_SCHEMA = vol.Schema(
     {
         DOMAIN: vol.Schema(
             {
-                vol.Optional(
-                    CONF_DEFAULT_INTERFACE, default=DEFAULT_DEFAULT_INTERFACE
-                ): cv.boolean,
+                vol.Optional(CONF_DEFAULT_INTERFACE): cv.boolean,
                 vol.Optional(CONF_IPV6, default=DEFAULT_IPV6): cv.boolean,
             }
         )
@@ -110,11 +113,59 @@ async def _async_get_instance(hass: HomeAssistant, **zcargs: Any) -> HaZeroconf:
     return zeroconf
 
 
+def _get_ip_route(dst_ip: str) -> Any:
+    """Get ip next hop."""
+    return IPRoute().route("get", dst=dst_ip)
+
+
+def _first_ip_nexthop_from_route(routes: Iterable) -> None | str:
+    """Find the first RTA_PREFSRC in the routes."""
+    _LOGGER.debug("Routes: %s", routes)
+    for route in routes:
+        for key, value in route["attrs"]:
+            if key == "RTA_PREFSRC":
+                return cast(str, value)
+    return None
+
+
+async def async_detect_interfaces_setting(hass: HomeAssistant) -> InterfaceChoice:
+    """Auto detect the interfaces setting when unset."""
+    routes = []
+    try:
+        routes = await hass.async_add_executor_job(_get_ip_route, MDNS_TARGET_IP)
+    except Exception as ex:  # pylint: disable=broad-except
+        _LOGGER.debug(
+            "The system could not auto detect routing data on your operating system; Zeroconf will broadcast on all interfaces",
+            exc_info=ex,
+        )
+        return InterfaceChoice.All
+
+    if not (first_ip := _first_ip_nexthop_from_route(routes)):
+        _LOGGER.debug(
+            "The system could not auto detect the nexthop for %s on your operating system; Zeroconf will broadcast on all interfaces",
+            MDNS_TARGET_IP,
+        )
+        return InterfaceChoice.All
+
+    if is_loopback(ip_address(first_ip)):
+        _LOGGER.debug(
+            "The next hop for %s is %s; Zeroconf will broadcast on all interfaces",
+            MDNS_TARGET_IP,
+            first_ip,
+        )
+        return InterfaceChoice.All
+
+    return InterfaceChoice.Default
+
+
 async def async_setup(hass: HomeAssistant, config: dict) -> bool:
     """Set up Zeroconf and make Home Assistant discoverable."""
     zc_config = config.get(DOMAIN, {})
     zc_args: dict = {}
-    if zc_config.get(CONF_DEFAULT_INTERFACE, DEFAULT_DEFAULT_INTERFACE):
+
+    if CONF_DEFAULT_INTERFACE not in zc_config:
+        zc_args["interfaces"] = await async_detect_interfaces_setting(hass)
+    elif zc_config[CONF_DEFAULT_INTERFACE]:
         zc_args["interfaces"] = InterfaceChoice.Default
     if not zc_config.get(CONF_IPV6, DEFAULT_IPV6):
         zc_args["ip_version"] = IPVersion.V4Only

homeassistant/components/zeroconf/manifest.json

@@ -2,7 +2,7 @@
   "domain": "zeroconf",
   "name": "Zero-configuration networking (zeroconf)",
   "documentation": "https://www.home-assistant.io/integrations/zeroconf",
-  "requirements": ["zeroconf==0.29.0"],
+  "requirements": ["zeroconf==0.29.0","pyroute2==0.5.18"],
   "dependencies": ["api"],
   "codeowners": ["@bdraco"],
   "quality_scale": "internal",

homeassistant/package_constraints.txt

@@ -23,6 +23,7 @@ netdisco==2.8.2
 paho-mqtt==1.5.1
 pillow==8.1.2
 pip>=8.0.3,<20.3
+pyroute2==0.5.18
 python-slugify==4.0.1
 pytz>=2021.1
 pyyaml==5.4.1

requirements_all.txt

@@ -1672,6 +1672,9 @@ pyrisco==0.3.1
 # homeassistant.components.rituals_perfume_genie
 pyrituals==0.0.2
 
+# homeassistant.components.zeroconf
+pyroute2==0.5.18
+
 # homeassistant.components.ruckus_unleashed
 pyruckus==0.12
 

requirements_test_all.txt

@@ -920,6 +920,9 @@ pyrisco==0.3.1
 # homeassistant.components.rituals_perfume_genie
 pyrituals==0.0.2
 
+# homeassistant.components.zeroconf
+pyroute2==0.5.18
+
 # homeassistant.components.ruckus_unleashed
 pyruckus==0.12
 

tests/components/zeroconf/test_init.py

@@ -31,6 +31,27 @@ PROPERTIES = {
 HOMEKIT_STATUS_UNPAIRED = b"1"
 HOMEKIT_STATUS_PAIRED = b"0"
 
+_ROUTE_NO_LOOPBACK = (
+    {
+        "attrs": [
+            ("RTA_TABLE", 254),
+            ("RTA_DST", "224.0.0.251"),
+            ("RTA_OIF", 4),
+            ("RTA_PREFSRC", "192.168.1.5"),
+        ],
+    },
+)
+_ROUTE_LOOPBACK = (
+    {
+        "attrs": [
+            ("RTA_TABLE", 254),
+            ("RTA_DST", "224.0.0.251"),
+            ("RTA_OIF", 4),
+            ("RTA_PREFSRC", "127.0.0.1"),
+        ],
+    },
+)
+
 
 def service_update_mock(zeroconf, services, handlers, *, limit_service=None):
     """Call service update handler."""
@@ -611,3 +632,62 @@ async def test_removed_ignored(hass, mock_zeroconf):
     assert len(mock_zeroconf.get_service_info.mock_calls) == 2
     assert mock_zeroconf.get_service_info.mock_calls[0][1][0] == "_service.added"
     assert mock_zeroconf.get_service_info.mock_calls[1][1][0] == "_service.updated"
+
+
+async def test_async_detect_interfaces_setting_non_loopback_route(hass, mock_zeroconf):
+    """Test without default interface config and the route returns a non-loopback address."""
+    with patch.object(hass.config_entries.flow, "async_init"), patch.object(
+        zeroconf, "HaServiceBrowser", side_effect=service_update_mock
+    ), patch(
+        "homeassistant.components.zeroconf.IPRoute.route",
+        return_value=_ROUTE_NO_LOOPBACK,
+    ):
+        mock_zeroconf.get_service_info.side_effect = get_service_info_mock
+        assert await async_setup_component(hass, zeroconf.DOMAIN, {zeroconf.DOMAIN: {}})
+        hass.bus.async_fire(EVENT_HOMEASSISTANT_STARTED)
+        await hass.async_block_till_done()
+
+    assert mock_zeroconf.called_with(interface_choice=InterfaceChoice.Default)
+
+
+async def test_async_detect_interfaces_setting_loopback_route(hass, mock_zeroconf):
+    """Test without default interface config and the route returns a loopback address."""
+    with patch.object(hass.config_entries.flow, "async_init"), patch.object(
+        zeroconf, "HaServiceBrowser", side_effect=service_update_mock
+    ), patch(
+        "homeassistant.components.zeroconf.IPRoute.route", return_value=_ROUTE_LOOPBACK
+    ):
+        mock_zeroconf.get_service_info.side_effect = get_service_info_mock
+        assert await async_setup_component(hass, zeroconf.DOMAIN, {zeroconf.DOMAIN: {}})
+        hass.bus.async_fire(EVENT_HOMEASSISTANT_STARTED)
+        await hass.async_block_till_done()
+
+    assert mock_zeroconf.called_with(interface_choice=InterfaceChoice.All)
+
+
+async def test_async_detect_interfaces_setting_empty_route(hass, mock_zeroconf):
+    """Test without default interface config and the route returns nothing."""
+    with patch.object(hass.config_entries.flow, "async_init"), patch.object(
+        zeroconf, "HaServiceBrowser", side_effect=service_update_mock
+    ), patch("homeassistant.components.zeroconf.IPRoute.route", return_value=[]):
+        mock_zeroconf.get_service_info.side_effect = get_service_info_mock
+        assert await async_setup_component(hass, zeroconf.DOMAIN, {zeroconf.DOMAIN: {}})
+        hass.bus.async_fire(EVENT_HOMEASSISTANT_STARTED)
+        await hass.async_block_till_done()
+
+    assert mock_zeroconf.called_with(interface_choice=InterfaceChoice.All)
+
+
+async def test_async_detect_interfaces_setting_exception(hass, mock_zeroconf):
+    """Test without default interface config and the route throws an exception."""
+    with patch.object(hass.config_entries.flow, "async_init"), patch.object(
+        zeroconf, "HaServiceBrowser", side_effect=service_update_mock
+    ), patch(
+        "homeassistant.components.zeroconf.IPRoute.route", side_effect=AttributeError
+    ):
+        mock_zeroconf.get_service_info.side_effect = get_service_info_mock
+        assert await async_setup_component(hass, zeroconf.DOMAIN, {zeroconf.DOMAIN: {}})
+        hass.bus.async_fire(EVENT_HOMEASSISTANT_STARTED)
+        await hass.async_block_till_done()
+
+    assert mock_zeroconf.called_with(interface_choice=InterfaceChoice.All)