Merge "Allow to disable DNS server announcement per subnet"

neutron/agent/linux/dhcp.py

@@ -882,12 +882,22 @@ class Dnsmasq(DhcpLocalProcess):
                  addr_mode == constants.IPV6_SLAAC)):
                 continue
             if subnet.dns_nameservers:
-                options.append(
+                if ((subnet.ip_version == 4 and
-                    self._format_option(
+                     subnet.dns_nameservers == ['0.0.0.0']) or
-                        subnet.ip_version, i, 'dns-server',
+                    (subnet.ip_version == 6 and
-                        ','.join(
+                     subnet.dns_nameservers == ['::'])):
-                            Dnsmasq._convert_to_literal_addrs(
+                    # Special case: Do not announce DNS servers
-                                subnet.ip_version, subnet.dns_nameservers))))
+                    options.append(
+                        self._format_option(
+                            subnet.ip_version, i, 'dns-server'))
+                else:
+                    options.append(
+                        self._format_option(
+                            subnet.ip_version, i, 'dns-server',
+                            ','.join(
+                                Dnsmasq._convert_to_literal_addrs(
+                                    subnet.ip_version,
+                                    subnet.dns_nameservers))))
             else:
                 # use the dnsmasq ip as nameservers only if there is no
                 # dns-server submitted by the server

neutron/tests/unit/agent/linux/test_dhcp.py

@@ -442,6 +442,13 @@ class FakeV4SubnetAgentWithManyDnsProvided(FakeV4Subnet):
         self.host_routes = []
 
 
+class FakeV4SubnetAgentWithNoDnsProvided(FakeV4Subnet):
+    def __init__(self):
+        super(FakeV4SubnetAgentWithNoDnsProvided, self).__init__()
+        self.dns_nameservers = ['0.0.0.0']
+        self.host_routes = []
+
+
 class FakeV4MultipleAgentsWithoutDnsProvided(object):
     def __init__(self):
         self.id = 'ffffffff-ffff-ffff-ffff-ffffffffffff'
@@ -469,6 +476,15 @@ class FakeV4AgentWithManyDnsProvided(object):
         self.namespace = 'qdhcp-ns'
 
 
+class FakeV4AgentWithNoDnsProvided(object):
+    def __init__(self):
+        self.id = 'ffffffff-ffff-ffff-ffff-ffffffffffff'
+        self.subnets = [FakeV4SubnetAgentWithNoDnsProvided()]
+        self.ports = [FakePort1(), FakePort2(), FakePort3(), FakeRouterPort(),
+                      FakePortMultipleAgents1()]
+        self.namespace = 'qdhcp-ns'
+
+
 class FakeV4SubnetMultipleAgentsWithDnsProvided(FakeV4Subnet):
     def __init__(self):
         super(FakeV4SubnetMultipleAgentsWithDnsProvided, self).__init__()
@@ -546,6 +562,19 @@ class FakeV6SubnetStateless(object):
         self.ipv6_ra_mode = None
 
 
+class FakeV6SubnetStatelessNoDnsProvided(object):
+    def __init__(self):
+        self.id = 'eeeeeeee-eeee-eeee-eeee-eeeeeeeeeeee'
+        self.ip_version = 6
+        self.cidr = 'ffea:3ba5:a17a:4ba3::/64'
+        self.gateway_ip = 'ffea:3ba5:a17a:4ba3::1'
+        self.enable_dhcp = True
+        self.dns_nameservers = ['::']
+        self.host_routes = []
+        self.ipv6_address_mode = constants.DHCPV6_STATELESS
+        self.ipv6_ra_mode = None
+
+
 class FakeV6SubnetStatelessBadPrefixLength(object):
     def __init__(self):
         self.id = 'eeeeeeee-eeee-eeee-eeee-eeeeeeeeeeee'
@@ -898,6 +927,14 @@ class FakeV6NetworkStatelessDHCP(object):
         self.namespace = 'qdhcp-ns'
 
 
+class FakeV6NetworkStatelessDHCPNoDnsProvided(object):
+    def __init__(self):
+        self.id = 'bbbbbbbb-bbbb-bbbb-bbbb-bbbbbbbbbbbb'
+        self.subnets = [FakeV6SubnetStatelessNoDnsProvided()]
+        self.ports = [FakeV6Port()]
+        self.namespace = 'qdhcp-ns'
+
+
 class FakeV6NetworkStatelessDHCPBadPrefixLength(object):
     def __init__(self):
         self.id = 'bbbbbbbb-bbbb-bbbb-bbbb-bbbbbbbbbbbb'
@@ -1429,6 +1466,18 @@ class TestDnsmasq(TestBase):
         self._test_output_opts_file(expected,
                                     FakeV4AgentWithManyDnsProvided())
 
+    def test_output_opts_file_agent_with_no_dns_provided(self):
+        expected = ('tag:tag0,'
+                    'option:dns-server\n'
+                    'tag:tag0,option:classless-static-route,'
+                    '169.254.169.254/32,192.168.0.1,0.0.0.0/0,192.168.0.1\n'
+                    'tag:tag0,249,169.254.169.254/32,192.168.0.1,0.0.0.0/0,'
+                    '192.168.0.1\n'
+                    'tag:tag0,option:router,192.168.0.1').lstrip()
+
+        self._test_output_opts_file(expected,
+                                    FakeV4AgentWithNoDnsProvided())
+
     def test_output_opts_file_multiple_agents_with_dns_provided(self):
         expected = ('tag:tag0,option:dns-server,8.8.8.8\n'
                     'tag:tag0,option:classless-static-route,'
@@ -2239,6 +2288,18 @@ class TestDnsmasq(TestBase):
         self.safe.assert_has_calls([mock.call(exp_host_name, exp_host_data),
                                     mock.call(exp_opt_name, exp_opt_data)])
 
+    def test_host_and_opts_file_on_stateless_dhcpv6_network_no_dns(self):
+        exp_host_name = '/dhcp/bbbbbbbb-bbbb-bbbb-bbbb-bbbbbbbbbbbb/host'
+        exp_opt_name = '/dhcp/bbbbbbbb-bbbb-bbbb-bbbb-bbbbbbbbbbbb/opts'
+        exp_opt_data = ('tag:tag0,option6:dns-server\n'
+                        'tag:tag0,'
+                        'option6:domain-search,openstacklocal').lstrip()
+        dm = self._get_dnsmasq(FakeV6NetworkStatelessDHCPNoDnsProvided())
+        dm._output_hosts_file()
+        dm._output_opts_file()
+        self.safe.assert_has_calls([mock.call(exp_host_name, ''),
+                                    mock.call(exp_opt_name, exp_opt_data)])
+
     def test_host_file_on_net_with_v6_slaac_and_v4(self):
         exp_host_name = '/dhcp/eeeeeeee-eeee-eeee-eeee-eeeeeeeeeeee/host'
         exp_host_data = (

releasenotes/notes/bug-1311040-dhcp-no-dns-09291c23e2ce800a.yaml

@@ -0,0 +1,16 @@
+---
+prelude: >
+    DNS server assignment can now be disabled in replies sent from the DHCP agent.
+features:
+  - |
+    It is now possible to instruct the DHCP agent not to supply any DNS server
+    address to their clients by setting the ``dns_nameservers`` attribute for
+    the corresponding subnet to ``0.0.0.0`` or ``::``, for IPv4 or IPv6 subnets
+    (respectively).
+upgrade:
+  - |
+    The functionality when a subnet has its DNS server set to ``0.0.0.0`` or
+    ``::`` has been changed with this release. The old behaviour was that each
+    DHCP agent would supply only its own IP address as the DNS server to its
+    clients. The new behaviour is that the DHCP agent will not supply any DNS
+    server IP address at all.