Merge "DHCPv6 - Use addr6_list in dnsmasq" into stable/train

neutron/agent/linux/dhcp.py

@@ -567,7 +567,89 @@ class Dnsmasq(DhcpLocalProcess):
                     constants.DHCPV6_STATELESS))),
             reverse=True)
 
-    def _iter_hosts(self):
+    def _merge_alloc_addr6_list(self, fixed_ips, v6_nets):
+        """Merge fixed_ips to ipv6 addr lists
+
+        If a port have multiple IPv6 addresses in the same subnet, merge the
+        into one entry listing all the addresess, creating a single dhcp-host
+        entry with the list of addresses defined allow dnsmasq to make all
+        addresses available as requests for leases arrive.
+
+        See dnsmasq-discuss mailing list: http://lists.thekelleys.org.uk/
+        pipermail/dnsmasq-discuss/2020q1/013743.html
+
+        """
+        by_subnet = {}
+        NewFip = collections.namedtuple('NewFip', 'subnet_id ip_address')
+        merged = []
+
+        for fip in fixed_ips:
+            if (fip.subnet_id in v6_nets and
+                    v6_nets[fip.subnet_id].ipv6_address_mode == (
+                            constants.DHCPV6_STATEFUL)):
+                if fip.subnet_id not in by_subnet:
+                    by_subnet.update({fip.subnet_id: []})
+                by_subnet[fip.subnet_id].append(fip.ip_address)
+            else:
+                merged.append(fip)
+
+        for subnet_id in by_subnet:
+            addr6_list = ','.join([self._format_address_for_dnsmasq(ip)
+                                   for ip in by_subnet[subnet_id]])
+            merged.append(NewFip(subnet_id=subnet_id,
+                                 ip_address=addr6_list))
+
+        return merged
+
+    def _get_dns_assignment(self, ip_address, dns_assignment):
+        """Get DNS assignment hostname and fqdn
+
+        In dnsmasq it is not possible to configure two dhcp-host
+        entries mapped to a single client mac address with IP
+        addresses in the same subnet. When recieving a requst
+        dnsmasq will match on the first entry in it's config,
+        and lease that address. The second entry will never be
+        used.
+
+        For IPv6 it is possible to add multiple IPv6 addresses
+        to a single dhcp-host entry by placing a list of addresses
+        in brackets, i.e [addr1][addr2][...]. See dnsmasq mailing
+        list: http://lists.thekelleys.org.uk/pipermail/
+        dnsmasq-discuss/2020q1/013671.html. Since we cannot have
+        two hostnames in the dhcp-host entry this method picks the
+        first hostname and fqdn it find's matching one of the IP's
+        in the fixed-ips in dns_assignment or the hostname is
+        generated based on the first fixed-ip.
+
+        :param ip_address: IP address or a list of IPv6 addresses
+        :param dns_ip_map: DNS IP Mapping
+        :param dns_assignment: DNS assignments
+        :return: hostname, fqdn
+        """
+        hostname, fqdn = None, None
+        ip_addresses = ip_address.replace('[', '').split(']')
+
+        if dns_assignment:
+            dns_ip_map = {d.ip_address: d for d in dns_assignment}
+            for addr in ip_addresses:
+                # If dns_name attribute is supported by ports API, return the
+                # dns_assignment generated by the Neutron server. Otherwise,
+                # generate hostname and fqdn locally (previous behaviour)
+                if addr in dns_ip_map:
+                    hostname = dns_ip_map[addr].hostname
+                    fqdn = dns_ip_map[addr].fqdn
+                    break
+
+        if hostname is None:
+            hostname = ('host-%s' %
+                        ip_addresses[0].replace('.', '-').replace(':', '-'))
+            fqdn = hostname
+            if self.conf.dns_domain:
+                fqdn = '%s.%s' % (fqdn, self.conf.dns_domain)
+
+        return hostname, fqdn
+
+    def _iter_hosts(self, merge_addr6_list=False):
         """Iterate over hosts.
 
         For each host on the network we yield a tuple containing:
@@ -590,11 +672,13 @@ class Dnsmasq(DhcpLocalProcess):
         for port in self.network.ports:
             fixed_ips = self._sort_fixed_ips_for_dnsmasq(port.fixed_ips,
                                                          v6_nets)
+            # TODO(hjensas): Drop this conditional and option once distros
+            #  generally have dnsmasq supporting addr6 list and range.
+            if self.conf.dnsmasq_enable_addr6_list and merge_addr6_list:
+                fixed_ips = self._merge_alloc_addr6_list(fixed_ips, v6_nets)
             # Confirm whether Neutron server supports dns_name attribute in the
             # ports API
             dns_assignment = getattr(port, 'dns_assignment', None)
-            if dns_assignment:
-                dns_ip_map = {d.ip_address: d for d in dns_assignment}
             for alloc in fixed_ips:
                 no_dhcp = False
                 no_opts = False
@@ -606,18 +690,9 @@ class Dnsmasq(DhcpLocalProcess):
                     # to provide options for a client that won't use DHCP
                     no_opts = addr_mode == constants.IPV6_SLAAC
 
-                # If dns_name attribute is supported by ports API, return the
-                # dns_assignment generated by the Neutron server. Otherwise,
-                # generate hostname and fqdn locally (previous behaviour)
-                if dns_assignment:
-                    hostname = dns_ip_map[alloc.ip_address].hostname
-                    fqdn = dns_ip_map[alloc.ip_address].fqdn
-                else:
-                    hostname = 'host-%s' % alloc.ip_address.replace(
-                        '.', '-').replace(':', '-')
-                    fqdn = hostname
-                    if self.conf.dns_domain:
-                        fqdn = '%s.%s' % (fqdn, self.conf.dns_domain)
+                hostname, fqdn = self._get_dns_assignment(alloc.ip_address,
+                                                          dns_assignment)
+
                 yield (port, alloc, hostname, fqdn, no_dhcp, no_opts)
 
     def _get_port_extra_dhcp_opts(self, port):
@@ -702,7 +777,7 @@ class Dnsmasq(DhcpLocalProcess):
                                    if s.enable_dhcp]
         # NOTE(ihrachyshka): the loop should not log anything inside it, to
         # avoid potential performance drop when lots of hosts are dumped
-        for host_tuple in self._iter_hosts():
+        for host_tuple in self._iter_hosts(merge_addr6_list=True):
             port, alloc, hostname, name, no_dhcp, no_opts = host_tuple
             if no_dhcp:
                 if not no_opts and self._get_port_extra_dhcp_opts(port):

neutron/cmd/sanity/checks.py

@@ -42,6 +42,7 @@ LOG = logging.getLogger(__name__)
 
 MINIMUM_DNSMASQ_VERSION = 2.67
 DNSMASQ_VERSION_DHCP_RELEASE6 = 2.76
+DNSMASQ_VERSION_HOST_ADDR6_LIST = 2.81
 MINIMUM_DIBBLER_VERSION = '1.0.1'
 CONNTRACK_GRE_MODULE = 'nf_conntrack_proto_gre'
 
@@ -199,6 +200,10 @@ def get_dnsmasq_version_with_dhcp_release6():
     return DNSMASQ_VERSION_DHCP_RELEASE6
 
 
+def get_dnsmasq_version_with_host_addr6_list():
+    return DNSMASQ_VERSION_HOST_ADDR6_LIST
+
+
 def dnsmasq_local_service_supported():
     cmd = ['dnsmasq', '--test', '--local-service']
     env = {'LC_ALL': 'C'}
@@ -223,6 +228,17 @@ def dnsmasq_version_supported():
         ver = float(m.group(1)) if m else 0
         if ver < MINIMUM_DNSMASQ_VERSION:
             return False
+        if (cfg.CONF.dnsmasq_enable_addr6_list is True and
+                ver < DNSMASQ_VERSION_HOST_ADDR6_LIST):
+            LOG.warning('Support for multiple IPv6 addresses in host '
+                        'entries was introduced in dnsmasq version '
+                        '%(required)s. Found dnsmasq version %(current)s, '
+                        'which does not support this feature. Unless support '
+                        'for multiple IPv6 addresses was backported to the '
+                        'running build of dnsmasq, the configuration option '
+                        'dnsmasq_enable_addr6_list should be set to False.',
+                        {'required': DNSMASQ_VERSION_HOST_ADDR6_LIST,
+                         'current': ver})
     except (OSError, RuntimeError, IndexError, ValueError) as e:
         LOG.debug("Exception while checking minimal dnsmasq version. "
                   "Exception: %s", e)

neutron/conf/agent/dhcp.py

@@ -110,6 +110,9 @@ DNSMASQ_OPTS = [
     cfg.IntOpt('dhcp_rebinding_time', default=0,
                help=_("DHCP rebinding time T2 (in seconds). If set to 0, it "
                       "will default to 7/8 of the lease time.")),
+    cfg.BoolOpt('dnsmasq_enable_addr6_list', default=False,
+                help=_("Enable dhcp-host entry with list of addresses when "
+                       "port has multiple IPv6 addresses in the same subnet."))
 ]
 
 

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

@@ -229,6 +229,25 @@ class FakeV6PortExtraOpt(object):
                     ip_version=constants.IP_VERSION_6)]
 
 
+class FakeV6PortMultipleFixedIpsSameSubnet(object):
+    def __init__(self, domain='openstacklocal'):
+        self.id = 'hhhhhhhh-hhhh-hhhh-hhhh-hhhhhhhhhhhh'
+        self.admin_state_up = True
+        self.device_owner = 'foo3'
+        self.fixed_ips = [
+            FakeIPAllocation('fdca:3ba5:a17a:4ba3::2',
+                             'ffffffff-ffff-ffff-ffff-ffffffffffff'),
+            FakeIPAllocation('fdca:3ba5:a17a:4ba3::4',
+                             'ffffffff-ffff-ffff-ffff-ffffffffffff')]
+        self.mac_address = '00:00:f3:aa:bb:cc'
+        self.device_id = 'fake_port6'
+        self.extra_dhcp_opts = []
+        self.dns_assignment = [FakeDNSAssignment('fdca:3ba5:a17a:4ba3::2',
+                                                 domain=domain),
+                               FakeDNSAssignment('fdca:3ba5:a17a:4ba3::4',
+                                                 domain=domain)]
+
+
 class FakeDualPortWithV6ExtraOpt(object):
     def __init__(self):
         self.id = 'hhhhhhhh-hhhh-hhhh-hhhh-hhhhhhhhhhhh'
@@ -1005,6 +1024,14 @@ class FakeNetworkWithV6SatelessAndV4DHCPSubnets(object):
         self.namespace = 'qdhcp-ns'
 
 
+class FakeV6NetworkStatefulDHCPSameSubnetFixedIps(object):
+    def __init__(self):
+        self.id = 'bbbbbbbb-bbbb-bbbb-bbbb-bbbbbbbbbbbb'
+        self.subnets = [FakeV6SubnetDHCPStateful()]
+        self.ports = [FakeV6PortMultipleFixedIpsSameSubnet()]
+        self.namespace = 'qdhcp-ns'
+
+
 class LocalChild(dhcp.DhcpLocalProcess):
     PORTS = {4: [4], 6: [6]}
 
@@ -2765,6 +2792,23 @@ 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_stateful_dhcpv6_same_subnet_fixedips(self):
+        self.conf.set_override('dnsmasq_enable_addr6_list', True)
+        exp_host_name = '/dhcp/bbbbbbbb-bbbb-bbbb-bbbb-bbbbbbbbbbbb/host'
+        exp_host_data = (
+            '00:00:f3:aa:bb:cc,host-fdca-3ba5-a17a-4ba3--2.openstacklocal.,'
+            '[fdca:3ba5:a17a:4ba3::2],[fdca:3ba5:a17a:4ba3::4]\n'.lstrip())
+        exp_opt_name = '/dhcp/bbbbbbbb-bbbb-bbbb-bbbb-bbbbbbbbbbbb/opts'
+        exp_opt_data = ('tag:subnet-ffffffff-ffff-ffff-ffff-ffffffffffff,'
+                        'option6:dns-server,[2001:0200:feed:7ac0::1]\n'
+                        'tag:subnet-ffffffff-ffff-ffff-ffff-ffffffffffff,'
+                        'option6:domain-search,openstacklocal').lstrip()
+        dm = self._get_dnsmasq(FakeV6NetworkStatefulDHCPSameSubnetFixedIps())
+        dm._output_hosts_file()
+        dm._output_opts_file()
+        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'

releasenotes/notes/dhcp-dnsmasq-dhcp-host-addr6-list-support-45d104b3f7ce220e.yaml

@@ -0,0 +1,25 @@
+---
+features:
+  - |
+    Adds support for configuring a list of IPv6 addresses for a dhcp-host entry
+    in the dnsmasq DHCP agent driver. For a port with multiple IPv6 fixed-ips
+    in the same subnet a single dhcp-host entry including all the addresses are
+    written to the dnsmasq dhcp-hostsfile.
+
+    Reserving multiple addresses for a host eases problems related to network
+    and chain-booting where each step in the boot process requests an address
+    using different DUID/IAID combinations. With a single address, only one
+    gets the "static" address and the boot process will fail on the following
+    steps. By reserving enough addresses for all the stages of the boot process
+    this problem is resolved. (See bug:
+    `#1861032 <https://bugs.launchpad.net/neutron/+bug/1861032>`_)
+
+    .. NOTE:: This requires dnsmasq version 2.81 or later. Some distributions
+              may backport this feauture to earlier dnsmasq version as part of
+              the packaging, check the distributions releasenotes.
+
+              Since the new configuration format is invalid in previous versions
+              of dnsmasq this feauture is *disabled* by default. To *enable* the
+              feature set the option ``dnsmasq_enable_addr6_list`` in DHCP agent
+              configuration to ``True``.
+