From 1dd35ff059ecd9cfa73591c104f43bfbc6451fad Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@koston.org>
Date: Mon, 8 Mar 2021 13:15:22 -1000
Subject: [PATCH] Catch dhcp setup permission errors sooner (#47639)

This solves an unexpected thread exception on macs when running as
a user intead of root
---
 homeassistant/components/dhcp/__init__.py | 18 ++++++++++--------
 tests/components/dhcp/test_init.py        | 10 ++++------
 2 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/homeassistant/components/dhcp/__init__.py b/homeassistant/components/dhcp/__init__.py
index d33c6159888..304eea24fd4 100644
--- a/homeassistant/components/dhcp/__init__.py
+++ b/homeassistant/components/dhcp/__init__.py
@@ -207,8 +207,11 @@ class DHCPWatcher(WatcherBase):
 
     async def async_start(self):
         """Start watching for dhcp packets."""
+        # disable scapy promiscuous mode as we do not need it
+        conf.sniff_promisc = 0
+
         try:
-            _verify_l2socket_creation_permission()
+            await self.hass.async_add_executor_job(_verify_l2socket_setup, FILTER)
         except (Scapy_Exception, OSError) as ex:
             if os.geteuid() == 0:
                 _LOGGER.error("Cannot watch for dhcp packets: %s", ex)
@@ -219,7 +222,7 @@ class DHCPWatcher(WatcherBase):
             return
 
         try:
-            await _async_verify_working_pcap(self.hass, FILTER)
+            await self.hass.async_add_executor_job(_verify_working_pcap, FILTER)
         except (Scapy_Exception, ImportError) as ex:
             _LOGGER.error(
                 "Cannot watch for dhcp packets without a functional packet filter: %s",
@@ -233,6 +236,7 @@ class DHCPWatcher(WatcherBase):
             prn=self.handle_dhcp_packet,
             store=0,
         )
+
         self._sniffer.start()
 
     def handle_dhcp_packet(self, packet):
@@ -283,7 +287,7 @@ def _format_mac(mac_address):
     return format_mac(mac_address).replace(":", "")
 
 
-def _verify_l2socket_creation_permission():
+def _verify_l2socket_setup(cap_filter):
     """Create a socket using the scapy configured l2socket.
 
     Try to create the socket
@@ -292,15 +296,13 @@ def _verify_l2socket_creation_permission():
     thread so we will not be able to capture
     any permission or bind errors.
     """
-    # disable scapy promiscuous mode as we do not need it
-    conf.sniff_promisc = 0
-    conf.L2socket()
+    conf.L2socket(filter=cap_filter)
 
 
-async def _async_verify_working_pcap(hass, cap_filter):
+def _verify_working_pcap(cap_filter):
     """Verify we can create a packet filter.
 
     If we cannot create a filter we will be listening for
     all traffic which is too intensive.
     """
-    await hass.async_add_executor_job(compile_filter, cap_filter)
+    compile_filter(cap_filter)
diff --git a/tests/components/dhcp/test_init.py b/tests/components/dhcp/test_init.py
index fc24c8201e2..f5cc5f1728d 100644
--- a/tests/components/dhcp/test_init.py
+++ b/tests/components/dhcp/test_init.py
@@ -281,7 +281,7 @@ async def test_setup_and_stop(hass):
     await hass.async_block_till_done()
 
     with patch("homeassistant.components.dhcp.AsyncSniffer.start") as start_call, patch(
-        "homeassistant.components.dhcp._verify_l2socket_creation_permission",
+        "homeassistant.components.dhcp._verify_l2socket_setup",
     ), patch(
         "homeassistant.components.dhcp.compile_filter",
     ):
@@ -307,7 +307,7 @@ async def test_setup_fails_as_root(hass, caplog):
     wait_event = threading.Event()
 
     with patch("os.geteuid", return_value=0), patch(
-        "homeassistant.components.dhcp._verify_l2socket_creation_permission",
+        "homeassistant.components.dhcp._verify_l2socket_setup",
         side_effect=Scapy_Exception,
     ):
         hass.bus.async_fire(EVENT_HOMEASSISTANT_STARTED)
@@ -330,7 +330,7 @@ async def test_setup_fails_non_root(hass, caplog):
     await hass.async_block_till_done()
 
     with patch("os.geteuid", return_value=10), patch(
-        "homeassistant.components.dhcp._verify_l2socket_creation_permission",
+        "homeassistant.components.dhcp._verify_l2socket_setup",
         side_effect=Scapy_Exception,
     ):
         hass.bus.async_fire(EVENT_HOMEASSISTANT_STARTED)
@@ -351,9 +351,7 @@ async def test_setup_fails_with_broken_libpcap(hass, caplog):
     )
     await hass.async_block_till_done()
 
-    with patch(
-        "homeassistant.components.dhcp._verify_l2socket_creation_permission",
-    ), patch(
+    with patch("homeassistant.components.dhcp._verify_l2socket_setup",), patch(
         "homeassistant.components.dhcp.compile_filter",
         side_effect=ImportError,
     ) as compile_filter, patch(