Avoid aiodns resolver memory leak (#5941)

* Avoid aiodns resolver memory leak

In certain cases, the aiodns resolver can leak memory. This also
leads to Fatal `Python error… ffi.from_handle()`. This addresses
the issue by ensuring that the resolver is properly closed
when it is no longer needed.

* Address coderabbitai feedback

* Fix pytest

* Fix pytest

supervisor/resolution/checks/dns_server.py

@@ -15,6 +15,24 @@ from ..const import DNS_CHECK_HOST, ContextType, IssueType
 from .base import CheckBase
 
 
+async def check_server(
+    loop: asyncio.AbstractEventLoop, server: str, qtype: str
+) -> None:
+    """Check a DNS server and report issues."""
+    ip_addr = server[6:] if server.startswith("dns://") else server
+    resolver = DNSResolver(loop=loop, nameservers=[ip_addr])
+    try:
+        await resolver.query(DNS_CHECK_HOST, qtype)
+    finally:
+
+        def _delete_resolver():
+            """Close resolver to avoid memory leaks."""
+            nonlocal resolver
+            del resolver
+
+        loop.call_later(1, _delete_resolver)
+
+
 def setup(coresys: CoreSys) -> CheckBase:
     """Check setup function."""
     return CheckDNSServer(coresys)
@@ -33,7 +51,7 @@ class CheckDNSServer(CheckBase):
         """Run check if not affected by issue."""
         dns_servers = self.dns_servers
         results = await asyncio.gather(
-            *[self._check_server(server) for server in dns_servers],
+            *[check_server(self.sys_loop, server, "A") for server in dns_servers],
             return_exceptions=True,
         )
         for i in (r for r in range(len(results)) if isinstance(results[r], DNSError)):
@@ -51,18 +69,12 @@ class CheckDNSServer(CheckBase):
             return False
 
         try:
-            await self._check_server(reference)
+            await check_server(self.sys_loop, reference, "A")
         except DNSError:
             return True
 
         return False
 
-    async def _check_server(self, server: str):
-        """Check a DNS server and report issues."""
-        ip_addr = server[6:] if server.startswith("dns://") else server
-        resolver = DNSResolver(nameservers=[ip_addr])
-        await resolver.query(DNS_CHECK_HOST, "A")
-
     @property
     def dns_servers(self) -> list[str]:
         """All user and system provided dns servers."""

supervisor/resolution/checks/dns_server_ipv6.py

@@ -3,15 +3,16 @@
 import asyncio
 from datetime import timedelta
 
-from aiodns import DNSResolver
 from aiodns.error import DNSError
 
+from supervisor.resolution.checks.dns_server import check_server
+
 from ...const import CoreState
 from ...coresys import CoreSys
 from ...jobs.const import JobCondition, JobExecutionLimit
 from ...jobs.decorator import Job
 from ...utils.sentry import async_capture_exception
-from ..const import DNS_CHECK_HOST, DNS_ERROR_NO_DATA, ContextType, IssueType
+from ..const import DNS_ERROR_NO_DATA, ContextType, IssueType
 from .base import CheckBase
 
 
@@ -33,7 +34,7 @@ class CheckDNSServerIPv6(CheckBase):
         """Run check if not affected by issue."""
         dns_servers = self.dns_servers
         results = await asyncio.gather(
-            *[self._check_server(server) for server in dns_servers],
+            *[check_server(self.sys_loop, server, "AAAA") for server in dns_servers],
             return_exceptions=True,
         )
         for i in (
@@ -58,19 +59,13 @@ class CheckDNSServerIPv6(CheckBase):
             return False
 
         try:
-            await self._check_server(reference)
+            await check_server(self.sys_loop, reference, "AAAA")
         except DNSError as dns_error:
             if dns_error.args[0] != DNS_ERROR_NO_DATA:
                 return True
 
         return False
 
-    async def _check_server(self, server: str):
-        """Check a DNS server and report issues."""
-        ip_addr = server[6:] if server.startswith("dns://") else server
-        resolver = DNSResolver(nameservers=[ip_addr])
-        await resolver.query(DNS_CHECK_HOST, "AAAA")
-
     @property
     def dns_servers(self) -> list[str]:
         """All user and system provided dns servers."""

tests/resolution/check/test_check.py

@@ -21,10 +21,6 @@ def fixture_mock_dns_query():
             "supervisor.resolution.checks.dns_server.DNSResolver.query",
             new_callable=AsyncMock,
         ),
-        patch(
-            "supervisor.resolution.checks.dns_server_ipv6.DNSResolver.query",
-            new_callable=AsyncMock,
-        ),
     ):
         yield
 

tests/resolution/check/test_check_dns_server_ipv6_error.py

@@ -15,7 +15,7 @@ from supervisor.resolution.const import ContextType, IssueType
 async def fixture_dns_query() -> AsyncMock:
     """Mock aiodns query."""
     with patch(
-        "supervisor.resolution.checks.dns_server_ipv6.DNSResolver.query",
+        "supervisor.resolution.checks.dns_server.DNSResolver.query",
         new_callable=AsyncMock,
     ) as dns_query:
         yield dns_query