Merge ~cgrabowski/maas:backport_safe_getaddrinfo_fix_3.4 into maas:3.4

[Christian Grabowski]

add test that hits _v6_lookup in safe_getaddrinfo and ensures
non-deferred answer
(cherry picked from commit 5c0dbab94c842269a6f06ded9f2378ff934d6bbf)

[Christian Grabowski (cgrabowski)]

self-approving backport

review: Approve

[MAAS Lander (maas-lander)]

UNIT TESTS
-b backport_safe_getaddrinfo_fix_3.4 lp:~cgrabowski/maas/+git/maas into -b 3.4 lp:~maas-committers/maas

STATUS: SUCCESS
COMMIT: 24be18a6df5521a8a29b52e1d0ce256be1c5858c

review: Approve

diff --git a/src/provisioningserver/utils/network.py b/src/provisioningserver/utils/network.py
index d6fb989..1ea4ec0 100644
--- a/src/provisioningserver/utils/network.py
+++ b/src/provisioningserver/utils/network.py
@@ -26,7 +26,7 @@ from zlib import crc32
 from netaddr import EUI, IPAddress, IPNetwork, IPRange
 from netaddr.core import AddrFormatError, NotRegisteredError
 import netifaces
-from twisted.internet.defer import inlineCallbacks
+from twisted.internet.defer import Deferred, inlineCallbacks
 from twisted.internet.interfaces import IResolver
 from twisted.names.client import getResolver
 from twisted.names.error import (
@@ -41,7 +41,7 @@ from provisioningserver.utils.ipaddr import get_ip_addr
 from provisioningserver.utils.iproute import get_ip_route
 from provisioningserver.utils.ps import running_in_container
 from provisioningserver.utils.shell import call_and_check, get_env_with_locale
-from provisioningserver.utils.twisted import synchronous
+from provisioningserver.utils.twisted import asynchronous, synchronous
 
 # Address families in /etc/network/interfaces that MAAS chooses to parse. All
 # other families are ignored.
@@ -751,7 +751,9 @@ def get_all_interface_addresses() -> Iterable[str]:
         yield from get_all_addresses_for_interface(interface)
 
 
-def safe_getaddrinfo(hostname, port, family=AF_INET, proto=IPPROTO_TCP):
+def safe_getaddrinfo(
+    hostname, port, family=AF_INET, proto=IPPROTO_TCP, timeout=10
+):
     if family in (
         AF_INET,
         0,
@@ -764,19 +766,27 @@ def safe_getaddrinfo(hostname, port, family=AF_INET, proto=IPPROTO_TCP):
         socket.SOCK_STREAM if proto == IPPROTO_TCP else socket.SOCK_DGRAM
     )
 
+    @asynchronous(timeout=timeout)
     @inlineCallbacks
     def _v6_lookup():
         resolver = getResolver()
         answers = yield resolver.lookupIPV6Address(hostname)
         return [
-            (AF_INET6, sock_type, proto, "", (ans.address, port, 0, 0))
+            (AF_INET6, sock_type, proto, "", (ans._address, port, 0, 0))
             for ans in answers[0]
         ]
 
     try:
         addr = IPAddress(hostname)
     except AddrFormatError:
-        return _v6_lookup()
+        result = _v6_lookup()
+        # this should only happen in tests where twisted is in the thread,
+        # but this is called from a synchronous context
+        if isinstance(result, Deferred) and result.result:
+            return result.result
+        # synchronous contexts should use sync_safe_getaddrinfo to ensure
+        # this is not a Deferred
+        return result
     else:
         return [(AF_INET6, sock_type, proto, "", (str(addr), port, 0, 0))]
 
diff --git a/src/provisioningserver/utils/tests/test_network.py b/src/provisioningserver/utils/tests/test_network.py
index 5101208..1ed3e6e 100644
--- a/src/provisioningserver/utils/tests/test_network.py
+++ b/src/provisioningserver/utils/tests/test_network.py
@@ -2566,12 +2566,34 @@ class TestSafeGetaddrinfo(MAASTestCase):
             (AF_INET6, socket.SOCK_STREAM, IPPROTO_TCP, "", ("::", 53, 0, 0))
         ]
         mock_resolver = Mock()
-        mock_resolver.lookupIPV6Address = lambda _: (
-            [Record_AAAA(address="::")],
-            [],
-            [],
+        mock_resolver.lookupIPV6Address = lambda _: succeed(
+            (
+                [Record_AAAA(address="::")],
+                [],
+                [],
+            )
         )
         get_resolver = self.patch(network_module, "getResolver")
         get_resolver.return_value = mock_resolver
         result = safe_getaddrinfo("::", 53, family=AF_INET6, proto=IPPROTO_TCP)
         self.assertCountEqual(expected, result)
+
+    def test_safe_get_addrinfo_uses_resolver_for_v6_with_hostname(self):
+        expected = [
+            (AF_INET6, socket.SOCK_STREAM, IPPROTO_TCP, "", ("::1", 53, 0, 0))
+        ]
+        mock_resolver = Mock()
+        mock_resolver.lookupIPV6Address = lambda _: succeed(
+            (
+                [Record_AAAA(address="::1")],
+                [],
+                [],
+            )
+        )
+        get_resolver = self.patch(network_module, "getResolver")
+        get_resolver.return_value = mock_resolver
+        # tests that _v6_lookup works in a synchronous context
+        result = safe_getaddrinfo(
+            "example.com", 53, family=AF_INET6, proto=IPPROTO_TCP
+        )
+        self.assertCountEqual(expected, result)