From d4f92ede9ed52cd0b9059d993e3cf1f42d5ff57e Mon Sep 17 00:00:00 2001
From: Brian Haley <brian.haley@hpe.com>
Date: Tue, 6 Sep 2016 14:44:41 -0400
Subject: [PATCH] Fix dhcp_release6 error when not supported

If the system does not have a version of dnsmasq that supports
dhcp_release6, warn about but otherwise handle it gracefully, and also
don't even try to execute it the next time.

Closes-Bug: #1622002
Related-Bug: #1624079
Change-Id: I6bb9547f9d9a9fcfb2357521f3f5bd1dc1dd5136
---
 neutron/agent/linux/dhcp.py                 | 13 +++++++++++++
 neutron/tests/unit/agent/linux/test_dhcp.py | 21 +++++++++++++++++++++
 2 files changed, 34 insertions(+)

diff --git a/neutron/agent/linux/dhcp.py b/neutron/agent/linux/dhcp.py
index 7f914af4826..94221bc3bd8 100644
--- a/neutron/agent/linux/dhcp.py
+++ b/neutron/agent/linux/dhcp.py
@@ -35,6 +35,7 @@ from neutron.agent.common import utils as agent_common_utils
 from neutron.agent.linux import external_process
 from neutron.agent.linux import ip_lib
 from neutron.agent.linux import iptables_manager
+from neutron.cmd.sanity import checks
 from neutron.common import constants as n_const
 from neutron.common import exceptions as n_exc
 from neutron.common import ipv6_utils
@@ -292,6 +293,8 @@ class Dnsmasq(DhcpLocalProcess):
 
     _ID = 'id:'
 
+    _IS_DHCP_RELEASE6_SUPPORTED = None
+
     @classmethod
     def check_version(cls):
         pass
@@ -442,10 +445,20 @@ class Dnsmasq(DhcpLocalProcess):
                                       service_name=DNSMASQ_SERVICE_NAME,
                                       monitored_process=pm)
 
+    def _is_dhcp_release6_supported(self):
+        if self._IS_DHCP_RELEASE6_SUPPORTED is None:
+            self._IS_DHCP_RELEASE6_SUPPORTED = checks.dhcp_release6_supported()
+            if not self._IS_DHCP_RELEASE6_SUPPORTED:
+                LOG.warning(_LW("dhcp_release6 is not present on this system, "
+                                "will not call it again."))
+        return self._IS_DHCP_RELEASE6_SUPPORTED
+
     def _release_lease(self, mac_address, ip, client_id=None,
                        server_id=None, iaid=None):
         """Release a DHCP lease."""
         if netaddr.IPAddress(ip).version == constants.IP_VERSION_6:
+            if not self._is_dhcp_release6_supported():
+                return
             cmd = ['dhcp_release6', '--iface', self.interface_name,
                    '--ip', ip, '--client-id', client_id,
                    '--server-id', server_id, '--iaid', iaid]
diff --git a/neutron/tests/unit/agent/linux/test_dhcp.py b/neutron/tests/unit/agent/linux/test_dhcp.py
index 97bdba87c75..f6ca3b100c5 100644
--- a/neutron/tests/unit/agent/linux/test_dhcp.py
+++ b/neutron/tests/unit/agent/linux/test_dhcp.py
@@ -850,6 +850,7 @@ class TestBase(TestConfBase):
 
         self.replace_p = mock.patch('neutron.common.utils.replace_file')
         self.execute_p = mock.patch('neutron.agent.common.utils.execute')
+        mock.patch('neutron.agent.linux.utils.execute').start()
         self.safe = self.replace_p.start()
         self.execute = self.execute_p.start()
 
@@ -1705,6 +1706,26 @@ class TestDnsmasq(TestBase):
         ipw.assert_has_calls([mock.call(['dhcp_release', None, ip2, mac2],
                              run_as_root=True), ])
 
+    def test_release_for_ipv6_lease_no_dhcp_release6(self):
+        dnsmasq = self._get_dnsmasq(FakeDualNetwork())
+
+        ip1 = 'fdca:3ba5:a17a::1'
+        mac1 = '00:00:80:aa:bb:cc'
+
+        old_leases = set([(ip1, mac1, None)])
+        dnsmasq._read_hosts_file_leases = mock.Mock(return_value=old_leases)
+        dnsmasq._read_v6_leases_file_leases = mock.Mock(
+            return_value={'fdca:3ba5:a17a::1': {'iaid': 0xff,
+                                                'client_id': 'client_id',
+                                                'server_id': 'server_id'}
+                          })
+        ipw = mock.patch(
+            'neutron.agent.linux.ip_lib.IpNetnsCommand.execute').start()
+        dnsmasq._IS_DHCP_RELEASE6_SUPPORTED = False
+        dnsmasq._release_unused_leases()
+        # Verify that dhcp_release6 is not called when it is not present
+        ipw.assert_not_called()
+
     def test_release_unused_leases_with_dhcp_port(self):
         dnsmasq = self._get_dnsmasq(FakeNetworkDhcpPort())
         ip1 = '192.168.1.2'