Merge "Ensure ip6tables are used only if ipv6 is enabled in kernel"

diff --cc neutron/agent/l3_agent.py
index d94ffe6d20488b7ffc185b16abf97cc482004049,84976fb69756f8801a8d890ad730b26366462575..f20fee878e3734e78f3d4890de0a4687053fc4e3
--- 1/neutron/agent/l3_agent.py
--- 2/neutron/agent/l3_agent.py
+++ b/neutron/agent/l3_agent.py
@@@ -143,102 -143,10 +144,103 @@@ class L3PluginApi(n_rpc.RpcProxy)
                           version='1.3')
  
  
 +class LinkLocalAddressPair(netaddr.IPNetwork):
 +    def __init__(self, addr):
 +        super(LinkLocalAddressPair, self).__init__(addr)
 +
 +    def get_pair(self):
 +        """Builds an address pair from the first and last addresses. """
 +        return (netaddr.IPNetwork("%s/%s" % (self.network, self.prefixlen)),
 +                netaddr.IPNetwork("%s/%s" % (self.broadcast, self.prefixlen)))
 +
 +
 +class LinkLocalAllocator(object):
 +    """Manages allocation of link local IP addresses.
 +
 +    These link local addresses are used for routing inside the fip namespaces.
 +    The associations need to persist across agent restarts to maintain
 +    consistency.  Without this, there is disruption in network connectivity
 +    as the agent rewires the connections with the new IP address assocations.
 +
 +    Persisting these in the database is unnecessary and would degrade
 +    performance.
 +    """
 +    def __init__(self, state_file, subnet):
 +        """Read the file with previous allocations recorded.
 +
 +        See the note in the allocate method for more detail.
 +        """
 +        self.state_file = state_file
 +        subnet = netaddr.IPNetwork(subnet)
 +
 +        self.allocations = {}
 +
 +        self.remembered = {}
 +        for line in self._read():
 +            key, cidr = line.strip().split(',')
 +            self.remembered[key] = LinkLocalAddressPair(cidr)
 +
 +        self.pool = set(LinkLocalAddressPair(s) for s in subnet.subnet(31))
 +        self.pool.difference_update(self.remembered.values())
 +
 +    def allocate(self, key):
 +        """Try to allocate a link local address pair.
 +
 +        I expect this to work in all cases because I expect the pool size to be
 +        large enough for any situation.  Nonetheless, there is some defensive
 +        programming in here.
 +
 +        Since the allocations are persisted, there is the chance to leak
 +        allocations which should have been released but were not.  This leak
 +        could eventually exhaust the pool.
 +
 +        So, if a new allocation is needed, the code first checks to see if
 +        there are any remembered allocations for the key.  If not, it checks
 +        the free pool.  If the free pool is empty then it dumps the remembered
 +        allocations to free the pool.  This final desparate step will not
 +        happen often in practice.
 +        """
 +        if key in self.remembered:
 +            self.allocations[key] = self.remembered.pop(key)
 +            return self.allocations[key]
 +
 +        if not self.pool:
 +            # Desparate times.  Try to get more in the pool.
 +            self.pool.update(self.remembered.values())
 +            self.remembered.clear()
 +            if not self.pool:
 +                # More than 256 routers on a compute node!
 +                raise RuntimeError(_("Cannot allocate link local address"))
 +
 +        self.allocations[key] = self.pool.pop()
 +        self._write_allocations()
 +        return self.allocations[key]
 +
 +    def release(self, key):
 +        self.pool.add(self.allocations.pop(key))
 +        self._write_allocations()
 +
 +    def _write_allocations(self):
 +        current = ["%s,%s\n" % (k, v) for k, v in self.allocations.items()]
 +        remembered = ["%s,%s\n" % (k, v) for k, v in self.remembered.items()]
 +        current.extend(remembered)
 +        self._write(current)
 +
 +    def _write(self, lines):
 +        with open(self.state_file, "w") as f:
 +            f.writelines(lines)
 +
 +    def _read(self):
 +        if not os.path.exists(self.state_file):
 +            return []
 +        with open(self.state_file) as f:
 +            return f.readlines()
 +
 +
  class RouterInfo(object):
  
-     def __init__(self, router_id, root_helper, use_namespaces, router):
+     def __init__(self, router_id, root_helper, use_namespaces, router,
+                  use_ipv6=False):
          self.router_id = router_id
          self.ex_gw_port = None
          self._snat_enabled = None