Fix network starting with no configured IPv4 addresses (#69030)

Co-authored-by: J. Nick Koston <nick@koston.org>

homeassistant/components/network/__init__.py

@@ -6,11 +6,16 @@ import logging
 
 from homeassistant.core import HomeAssistant, callback
 from homeassistant.exceptions import HomeAssistantError
-from homeassistant.helpers.typing import ConfigType
+from homeassistant.helpers.typing import UNDEFINED, ConfigType, UndefinedType
 from homeassistant.loader import bind_hass
 
 from . import util
-from .const import IPV4_BROADCAST_ADDR, PUBLIC_TARGET_IP
+from .const import (
+    IPV4_BROADCAST_ADDR,
+    LOOPBACK_TARGET_IP,
+    MDNS_TARGET_IP,
+    PUBLIC_TARGET_IP,
+)
 from .models import Adapter
 from .network import Network, async_get_network
 
@@ -26,7 +31,7 @@ async def async_get_adapters(hass: HomeAssistant) -> list[Adapter]:
 
 @bind_hass
 async def async_get_source_ip(
-    hass: HomeAssistant, target_ip: str = PUBLIC_TARGET_IP
+    hass: HomeAssistant, target_ip: str | UndefinedType = UNDEFINED
 ) -> str:
     """Get the source ip for a target ip."""
     adapters = await async_get_adapters(hass)
@@ -35,7 +40,15 @@ async def async_get_source_ip(
         if adapter["enabled"] and (ipv4s := adapter["ipv4"]):
             all_ipv4s.extend([ipv4["address"] for ipv4 in ipv4s])
 
+    if target_ip is UNDEFINED:
+        source_ip = (
+            util.async_get_source_ip(PUBLIC_TARGET_IP)
+            or util.async_get_source_ip(MDNS_TARGET_IP)
+            or util.async_get_source_ip(LOOPBACK_TARGET_IP)
+        )
+    else:
         source_ip = util.async_get_source_ip(target_ip)
+
     if not all_ipv4s:
         _LOGGER.warning(
             "Because the system does not have any enabled IPv4 addresses, source address detection may be inaccurate"

homeassistant/components/network/const.py

@@ -17,6 +17,7 @@ ATTR_ADAPTERS: Final = "adapters"
 ATTR_CONFIGURED_ADAPTERS: Final = "configured_adapters"
 DEFAULT_CONFIGURED_ADAPTERS: list[str] = []
 
+LOOPBACK_TARGET_IP: Final = "127.0.0.1"
 MDNS_TARGET_IP: Final = "224.0.0.251"
 PUBLIC_TARGET_IP: Final = "8.8.8.8"
 IPV4_BROADCAST_ADDR: Final = "255.255.255.255"

tests/components/network/test_init.py

@@ -27,6 +27,21 @@ def _mock_socket(sockname):
     return mock_socket
 
 
+def _mock_cond_socket(sockname):
+    class CondMockSock(MagicMock):
+        def connect(self, addr):
+            """Mock connect that stores addr."""
+            self._addr = addr[0]
+
+        def getsockname(self):
+            """Return addr if it matches the mock sockname."""
+            if self._addr == sockname:
+                return [sockname]
+            raise AttributeError()
+
+    return CondMockSock()
+
+
 def _mock_socket_exception(exc):
     mock_socket = MagicMock()
     mock_socket.getsockname = Mock(side_effect=exc)
@@ -650,3 +665,24 @@ async def test_async_get_source_ip_cannot_be_determined_and_no_enabled_addresses
         await hass.async_block_till_done()
         with pytest.raises(HomeAssistantError):
             await network.async_get_source_ip(hass, MDNS_TARGET_IP)
+
+
+async def test_async_get_source_ip_no_ip_loopback(hass, hass_storage, caplog):
+    """Test getting the source ip address when all adapters are disabled no target is specified."""
+    hass_storage[STORAGE_KEY] = {
+        "version": STORAGE_VERSION,
+        "key": STORAGE_KEY,
+        "data": {ATTR_CONFIGURED_ADAPTERS: ["eth1"]},
+    }
+
+    with patch(
+        "homeassistant.components.network.util.ifaddr.get_adapters",
+        return_value=[],
+    ), patch(
+        "homeassistant.components.network.util.socket.socket",
+        return_value=_mock_cond_socket(_LOOPBACK_IPADDR),
+    ):
+        assert await async_setup_component(hass, DOMAIN, {DOMAIN: {}})
+        await hass.async_block_till_done()
+
+        assert await network.async_get_source_ip(hass) == "127.0.0.1"