From 74a30af79ba491197d3f48c7b07e2e2217249de7 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Mon, 9 Aug 2021 14:13:55 -0500
Subject: [PATCH] Always set interfaces explicitly when IPv6 is present
 (#54268)

---
 homeassistant/components/zeroconf/__init__.py | 17 +++----
 tests/components/zeroconf/test_init.py        | 47 +++++++++++++++++--
 2 files changed, 51 insertions(+), 13 deletions(-)

diff --git a/homeassistant/components/zeroconf/__init__.py b/homeassistant/components/zeroconf/__init__.py
index cdb46318578..e7132f56b55 100644
--- a/homeassistant/components/zeroconf/__init__.py
+++ b/homeassistant/components/zeroconf/__init__.py
@@ -142,7 +142,15 @@ async def async_setup(hass: HomeAssistant, config: dict) -> bool:
     zc_args: dict = {}
 
     adapters = await network.async_get_adapters(hass)
-    if _async_use_default_interface(adapters):
+
+    ipv6 = True
+    if not any(adapter["enabled"] and adapter["ipv6"] for adapter in adapters):
+        ipv6 = False
+        zc_args["ip_version"] = IPVersion.V4Only
+    else:
+        zc_args["ip_version"] = IPVersion.All
+
+    if not ipv6 and _async_use_default_interface(adapters):
         zc_args["interfaces"] = InterfaceChoice.Default
     else:
         interfaces = zc_args["interfaces"] = []
@@ -158,13 +166,6 @@ async def async_setup(hass: HomeAssistant, config: dict) -> bool:
             if adapter["ipv6"] and adapter["index"] not in interfaces:
                 interfaces.append(adapter["index"])
 
-    ipv6 = True
-    if not any(adapter["enabled"] and adapter["ipv6"] for adapter in adapters):
-        ipv6 = False
-        zc_args["ip_version"] = IPVersion.V4Only
-    else:
-        zc_args["ip_version"] = IPVersion.All
-
     aio_zc = await _async_get_instance(hass, **zc_args)
     zeroconf = cast(HaZeroconf, aio_zc.zeroconf)
     zeroconf_types, homekit_models = await asyncio.gather(
diff --git a/tests/components/zeroconf/test_init.py b/tests/components/zeroconf/test_init.py
index e1e346621fe..0db8f0f5227 100644
--- a/tests/components/zeroconf/test_init.py
+++ b/tests/components/zeroconf/test_init.py
@@ -794,11 +794,6 @@ async def test_async_detect_interfaces_setting_empty_route(hass, mock_async_zero
     ), patch(
         "homeassistant.components.zeroconf.AsyncServiceInfo",
         side_effect=get_service_info_mock,
-    ), patch(
-        "socket.if_nametoindex",
-        side_effect=lambda iface: {"eth0": 1, "eth1": 2, "eth2": 3, "vtun0": 4}.get(
-            iface, 0
-        ),
     ):
         assert await async_setup_component(hass, zeroconf.DOMAIN, {zeroconf.DOMAIN: {}})
         hass.bus.async_fire(EVENT_HOMEASSISTANT_STARTED)
@@ -827,3 +822,45 @@ async def test_get_announced_addresses(hass, mock_async_zeroconf):
     first_ip = ip_address("192.168.1.5").packed
     actual = _get_announced_addresses(_ADAPTERS_WITH_MANUAL_CONFIG, first_ip)
     assert actual[0] == first_ip and set(actual) == expected
+
+
+_ADAPTER_WITH_DEFAULT_ENABLED_AND_IPV6 = [
+    {
+        "auto": True,
+        "default": True,
+        "enabled": True,
+        "index": 1,
+        "ipv4": [{"address": "192.168.1.5", "network_prefix": 23}],
+        "ipv6": [
+            {
+                "address": "fe80::dead:beef:dead:beef",
+                "network_prefix": 64,
+                "flowinfo": 1,
+                "scope_id": 3,
+            }
+        ],
+        "name": "eth1",
+    }
+]
+
+
+async def test_async_detect_interfaces_explicitly_set_ipv6(hass, mock_async_zeroconf):
+    """Test interfaces are explicitly set when IPv6 is present."""
+    with patch("homeassistant.components.zeroconf.HaZeroconf") as mock_zc, patch.object(
+        hass.config_entries.flow, "async_init"
+    ), patch.object(
+        zeroconf, "HaAsyncServiceBrowser", side_effect=service_update_mock
+    ), patch(
+        "homeassistant.components.zeroconf.network.async_get_adapters",
+        return_value=_ADAPTER_WITH_DEFAULT_ENABLED_AND_IPV6,
+    ), patch(
+        "homeassistant.components.zeroconf.AsyncServiceInfo",
+        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_zc.mock_calls[0] == call(
+        interfaces=["192.168.1.5", 1], ip_version=IPVersion.All
+    )