slapos.core: introduce ipv6_range for each partition

slapos.cfg.example

@@ -32,6 +32,7 @@ tap_ipv6 = true
 # You can choose any other local network which does not conflict with your
 # current machine configuration
 ipv4_local_network = 10.0.0.0/16
+partition_has_ipv6_range = true
 
 # to enable, change to [firewall]
 [disabled-firewall]

slapos/format.py

@@ -57,7 +57,7 @@ import six
 import lxml.etree
 import xml_marshaller.xml_marshaller
 
-from slapos.util import dumps, mkdir_p, ipv6FromBin, binFromIpv6, lenNetmaskIpv6
+from slapos.util import dumps, mkdir_p, ipv6FromBin, binFromIpv6, lenNetmaskIpv6, getPartitionIpv6Addr, getPartitionIpv6Range, getTapIpv6Range, netmaskFromLenIPv6
 import slapos.slap as slap
 from slapos import version
 from slapos import manager as slapmanager
@@ -239,7 +239,7 @@ class Computer(object):
   """Object representing the computer"""
 
   def __init__(self, reference, interface=None, addr=None, netmask=None,
-               ipv6_interface=None, software_user='slapsoft',
+               ipv6_interface=None, partition_has_ipv6_range=None, software_user='slapsoft',
                tap_gateway_interface=None, tap_ipv6=None,
                instance_root=None, software_root=None, instance_storage_home=None,
                partition_list=None, config=None):
@@ -256,6 +256,9 @@ class Computer(object):
     self.address = addr
     self.netmask = netmask
     self.ipv6_interface = ipv6_interface
+    self.partition_has_ipv6_range = partition_has_ipv6_range
+    print("DEBUG CONF1")
+    print(self.partition_has_ipv6_range)
     self.software_user = software_user
     self.tap_gateway_interface = tap_gateway_interface
     self.tap_ipv6 = tap_ipv6
@@ -406,7 +409,7 @@ class Computer(object):
       archive.writestr(saved_filename, xml_content, zipfile.ZIP_DEFLATED)
 
   @classmethod
-  def load(cls, path_to_xml, reference, ipv6_interface, tap_gateway_interface,
+  def load(cls, path_to_xml, reference, ipv6_interface, partition_has_ipv6_range, tap_gateway_interface,
            tap_ipv6, instance_root=None, software_root=None, config=None):
     """
     Create a computer object from a valid xml file.
@@ -427,6 +430,7 @@ class Computer(object):
         addr=dumped_dict['address'],
         netmask=dumped_dict['netmask'],
         ipv6_interface=ipv6_interface,
+        partition_has_ipv6_range=partition_has_ipv6_range,
         software_user=dumped_dict.get('software_user', 'slapsoft'),
         tap_gateway_interface=tap_gateway_interface,
         tap_ipv6=tap_ipv6,
@@ -463,6 +467,7 @@ class Computer(object):
         tun = Tun("slaptun" + str(partition_index), partition_index, partition_amount)
 
       address_list = partition_dict['address_list']
+      ipv6_range = partition_dict.get('ipv6_range', {})
       external_storage_list = partition_dict.get('external_storage_list', [])
 
       partition = Partition(
@@ -470,6 +475,7 @@ class Computer(object):
           path=partition_dict['path'],
           user=user,
           address_list=address_list,
+          ipv6_range=ipv6_range,
           tap=tap,
           tun=tun if config.create_tun else None,
           external_storage_list=external_storage_list,
@@ -558,7 +564,7 @@ class Computer(object):
     ####################
     if alter_network:
       if self.address is not None:
-        self.interface.addIPv6Address(self.address, self.netmask)
+        self.interface._addSystemAddress(self.address, self.netmask)
 
       if create_tap and self.tap_gateway_interface:
         gateway_addr_dict = getIfaceAddressIPv4(self.tap_gateway_interface)
@@ -567,6 +573,11 @@ class Computer(object):
                               len(self.partition_list))
         assert(len(self.partition_list) <= len(tap_address_list))
 
+      if self.partition_has_ipv6_range:
+        print("WITH RANGE")
+        print(alter_network)
+        self.interface.allowUseInexistingIpv6Address()
+
       self._speedHackAddAllOldIpsToInterface()
 
     try:
@@ -610,12 +621,13 @@ class Computer(object):
             if self.tap_ipv6:
               if not partition.tap.ipv6_addr:
                 # create a new IPv6 randomly for the tap
-                ipv6_dict = self.interface.addIPv6Address(tap=partition.tap)
+                ipv6_dict = self.interface.addIPv6Address(partition_index, tap=partition.tap)
                 partition.tap.ipv6_addr = ipv6_dict['addr']
                 partition.tap.ipv6_netmask = ipv6_dict['netmask']
               else:
                 # make sure the tap has its IPv6
                 self.interface.addIPv6Address(
+                        partition_index=partition_index,
                         addr=partition.tap.ipv6_addr,
                         netmask=partition.tap.ipv6_netmask,
                         tap=partition.tap)
@@ -641,19 +653,15 @@ class Computer(object):
             partition.tun.createWithOwner(owner)
             partition.tun.createRoutes()
 
-        # Reconstructing partition's directory
-        partition.createPath(alter_user)
-        partition.createExternalPath(alter_user)
-
           # Reconstructing partition's address
           # There should be two addresses on each Computer Partition:
           #  * local IPv4, took from slapformat:ipv4_local_network
           #  * global IPv6
           if not partition.address_list:
-          # regenerate
+            # generate new addresses
             partition.address_list.append(self.interface.addIPv4LocalAddress())
-          partition.address_list.append(self.interface.addIPv6Address())
-        elif alter_network:
+            partition.address_list.append(self.interface.addIPv6Address(partition_index))
+          else:
             # regenerate list of addresses
             old_partition_address_list = partition.address_list
             partition.address_list = []
@@ -663,21 +671,40 @@ class Computer(object):
                 (old_partition_address_list,))
             if not any(netaddr.valid_ipv6(q['addr'])
                        for q in old_partition_address_list):
-            raise ValueError('Not valid ipv6 addresses loaded')
+              raise ValueError('No valid IPv6 address loaded from XML config')
             if not any(netaddr.valid_ipv4(q['addr'])
                        for q in old_partition_address_list):
-            raise ValueError('Not valid ipv6 addresses loaded')
+              raise ValueError('No valid IPv4 address loaded from XML config')
 
             for address in old_partition_address_list:
               if netaddr.valid_ipv6(address['addr']):
                 partition.address_list.append(self.interface.addIPv6Address(
+                  partition_index,
                   address['addr'],
                   address['netmask']))
               elif netaddr.valid_ipv4(address['addr']):
                 partition.address_list.append(self.interface.addIPv4LocalAddress(
                   address['addr']))
               else:
+                # should never happen since there are exactly 1 valid IPv6 and 1
+                # valid IPv4 in old_partition_address_list
                 raise ValueError('Address %r is incorrect' % address['addr'])
+
+          # Reconstructing partiton's IPv6 range
+          if self.partition_has_ipv6_range:
+            if not partition.ipv6_range:
+              # generate new IPv6 range
+              partition.ipv6_range = self.interface.generateIPv6Range(partition_index)
+            else:
+              if not netaddr.valid_ipv6(partition.ipv6_range['addr']):
+                raise ValueError('existing IPv6 range %r is incorrect', partition.ipv6_range['addr'])
+          else:
+            partition.ipv6_range = {}
+
+        # Reconstructing partition's directory
+        partition.createPath(alter_user)
+        partition.createExternalPath(alter_user)
+
     finally:
       for manager in self._manager_list:
         manager.formatTearDown(self)
@@ -689,13 +716,14 @@ class Partition(object):
   resource_file = ".slapos-resource"
 
   def __init__(self, reference, path, user, address_list,
-               tap, external_storage_list=[], tun=None):
+               ipv6_range, tap, external_storage_list=[], tun=None):
     """
     Attributes:
       reference: String, the name of the partition.
       path: String, the path to the partition folder.
       user: User, the user linked to this partition.
       address_list: List of associated IP addresses.
+      ipv6_range: IPv6 range given to this partiton (dict with 'addr' and 'netmask').
       tap: Tap, the tap interface linked to this partition e.g. used as a gateway for kvm
       tun: Tun interface used for special apps simulating ethernet connections
       external_storage_list: Base path list of folder to format for data storage
@@ -705,12 +733,13 @@ class Partition(object):
     self.path = str(path)
     self.user = user
     self.address_list = address_list or []
+    self.ipv6_range = ipv6_range or {}
     self.tap = tap
     self.tun = tun
     self.external_storage_list = []
 
   def __getinitargs__(self):
-    return (self.reference, self.path, self.user, self.address_list, self.tap, self.tun)
+    return (self.reference, self.path, self.user, self.address_list, self.ipv6_range, self.tap, self.tun)
 
   def createPath(self, alter_user=True):
     """
@@ -1068,13 +1097,10 @@ class Interface(object):
                            for q in netifaces.ifaddresses(interface_name)[af]
                            ]:
       # add an address
-      callAndRead(['ip', 'addr', 'add', address_string, 'dev', interface_name])
-
-      # Fake success for local ipv4
-      if not ipv6:
-        return True
+      code, _ = callAndRead(['ip', 'addr', 'add', address_string, 'dev', interface_name])
 
-      # wait few moments
+      if code != 0:
+        return False
       time.sleep(2)
 
     # Fake success for local ipv4
@@ -1128,7 +1154,7 @@ class Interface(object):
       # confirmed to be configured
       return dict(addr=addr, netmask=netmask)
 
-  def addIPv6Address(self, addr=None, netmask=None, tap=None):
+  def addIPv6Address(self, partition_index, addr=None, netmask=None, tap=None):
     """
     Adds IPv6 address to interface.
 
@@ -1138,6 +1164,9 @@ class Interface(object):
     address. If it is not possible (ex. because network changed), calculate new
     address.
 
+    If tap is specified, tap will get actually an IPv6 range (and not a single
+    address) 16 bits smaller than the range of the interface.
+
     Args:
       addr: Wished address to be added to interface.
       netmask: Wished netmask to be used.
@@ -1193,38 +1222,65 @@ class Interface(object):
             self._logger.warning('Impossible to add old public IPv6 %s. '
                 'Generating new IPv6 address.' % addr)
 
-    # Try 10 times to add address, raise in case if not possible
-    try_num = 10
-    netmask = address_dict['netmask']
+    address_dict['netmask'] = lenNetmaskIpv6(address_dict['netmask'])
     if tap:
-      netmask_len = lenNetmaskIpv6(netmask)
-      prefix = binFromIpv6(address_dict['addr'])[:netmask_len]
-      netmask_len += 16
-      # we generate a subnetwork for the tap
-      # the subnetwork has 16 bits more than the interface network
-      # make sure we have at least 2 IPs in the subnetwork
-      if netmask_len >= 128:
-        self._logger.error('Interface %s has netmask %s which is too big for generating IPv6 on taps.' % (interface_name, netmask))
-        raise AddressGenerationError(addr)
-      netmask = ipv6FromBin('1'*128) # the netmask of the tap itself is always 128 bits
-
-    while try_num > 0:
-      if tap:
-        addr = ipv6FromBin(prefix
-          + bin(random.randint(1, 65000))[2:].zfill(16)
-          + '1' * (128 - netmask_len))
+      result_addr = getTapIpv6Range(address_dict, partition_index)
     else:
-        addr = ':'.join(address_dict['addr'].split(':')[:-1] + ['%x' % (
-          random.randint(1, 65000), )])
-        socket.inet_pton(socket.AF_INET6, addr)
-      if (dict(addr=addr, netmask=netmask) not in
-            self.getGlobalScopeAddressList(tap=tap)):
-        # Checking the validity of the IPv6 address
-        if self._addSystemAddress(addr, netmask, tap=tap):
-          return dict(addr=addr, netmask=netmask)
-        try_num -= 1
+      result_addr = getPartitionIpv6Addr(address_dict, partition_index)
+    # restore netmask as bitmask
+    result_addr['netmask'] = netmaskFromLenIPv6(result_addr['netmask'])
 
-    raise AddressGenerationError(addr)
+    self._addSystemAddress(result_addr['addr'], result_addr['netmask'], tap=tap)
+    return result_addr
+
+  def generateIPv6Range(self, i):
+    """
+    Generate an IPv6 range included in the IPv6 range of the interface. The IPv6 range depends on the partition index i.
+
+    There is no need to actually add this range anywhere because allowUseInexistingIpv6Address() has already been called.
+
+    Returns:
+      dict(addr=address, netmask=netmask, network=addr/CIDR).
+
+    Raises:
+      ValueError: Couldn't construct valid address with existing
+          one's on the interface.
+      NoAddressOnInterface: There's no address on the interface to construct
+          an address with.
+    """
+    interface_name = self.ipv6_interface or self.name
+
+    # Getting one address of the interface as base of the next addresses
+    interface_addr_list = self.getGlobalScopeAddressList()
+    # No address found
+    if len(interface_addr_list) == 0:
+      raise NoAddressOnInterface(interface_name)
+    address_dict = interface_addr_list[0]
+
+    address_dict['netmask'] = lenNetmaskIpv6(address_dict['netmask'])
+    ipv6_range = getPartitionIpv6Range(address_dict, i)
+    ipv6_range['network'] = '{addr}/{netmask}'.format(**ipv6_range)
+    ipv6_range['netmask'] = netmaskFromLenIPv6(ipv6_range['netmask'])
+    return ipv6_range
+
+  def allowUseInexistingIpv6Address(self):
+    # This will allow the usage of unexisting IPv6 adrdresses.
+
+    # Getting the global IPv6 range of the computer
+    interface_addr_list = self.getGlobalScopeAddressList()
+    # No address found
+    if len(interface_addr_list) == 0:
+      raise NoAddressOnInterface(interface_name)
+    address_dict = interface_addr_list[0]
+    addr = address_dict['addr']
+    netmask = address_dict['netmask'].split('/')[1]
+
+    self._logger.debug('sysctl net.ipv6.ip_nonlocal_bind=1')
+    callAndRead(['sysctl', 'net.ipv6.ip_nonlocal_bind=1'])
+    _, result = callAndRead(['ip', '-6', 'route', 'show', 'table', 'local', '%s/%s' % (addr, netmask)])
+    if not 'dev lo' in result:
+      self._logger.debug(' ip -6 route add local %s/%s dev lo', addr, netmask)
+      callAndRead(['ip', '-6', 'route', 'add', 'local', '%s/%s' % (addr, netmask), 'dev', 'lo'])
 
 
 def parse_computer_definition(conf, definition_path):
@@ -1250,6 +1306,7 @@ def parse_computer_definition(conf, definition_path):
       addr=address,
       netmask=netmask,
       ipv6_interface=conf.ipv6_interface,
+      partition_has_ipv6_range=conf.partition_has_ipv6_range,
       software_user=computer_definition.get('computer', 'software_user'),
       tap_gateway_interface=conf.tap_gateway_interface,
       tap_ipv6=conf.tap_ipv6,
@@ -1264,6 +1321,10 @@ def parse_computer_definition(conf, definition_path):
     for a in computer_definition.get(section, 'address').split():
       address, netmask = a.split('/')
       address_list.append(dict(addr=address, netmask=netmask))
+    ipv6_range_network = computer_definition.get(section, 'ipv6_range')
+    addr, netmask = ipv6_range_network.split('/')
+    netmask = netmaskFromLenIPv6(int(netmask))
+    ipv6_range = {'addr' : address, 'netmask' : netmask, 'network' : ipv6_range_network}
     tap = Tap(computer_definition.get(section, 'network_interface'))
     tun = Tun("slaptun" + str(partition_number),
               partition_number,
@@ -1273,6 +1334,7 @@ def parse_computer_definition(conf, definition_path):
                                             computer_definition.get(section, 'pathname')),
                           user=user,
                           address_list=address_list,
+                          ipv6_range=ipv6_range,
                           tap=tap, tun=tun)
     partition_list.append(partition)
   computer.partition_list = partition_list
@@ -1290,6 +1352,7 @@ def parse_computer_xml(conf, xml_path):
     computer = Computer.load(xml_path,
                              reference=conf.computer_id,
                              ipv6_interface=conf.ipv6_interface,
+                             partition_has_ipv6_range=conf.partition_has_ipv6_range,
                              tap_gateway_interface=conf.tap_gateway_interface,
                              tap_ipv6=conf.tap_ipv6,
                              software_root=conf.software_root,
@@ -1308,6 +1371,7 @@ def parse_computer_xml(conf, xml_path):
       addr=None,
       netmask=None,
       ipv6_interface=conf.ipv6_interface,
+      partition_has_ipv6_range=conf.partition_has_ipv6_range,
       software_user=conf.software_user,
       tap_gateway_interface=conf.tap_gateway_interface,
       tap_ipv6=conf.tap_ipv6,
@@ -1334,6 +1398,7 @@ def parse_computer_xml(conf, xml_path):
           conf.partition_base_name, i)),
         user=User('%s%s' % (conf.user_base_name, i)),
         address_list=None,
+        ipv6_range=None,
         tap=Tap('%s%s' % (conf.tap_base_name, i)),
         tun=Tun('slaptun' + str(i), i, partition_amount) if conf.create_tun else None
     )
@@ -1355,6 +1420,7 @@ def write_computer_definition(conf, computer):
     for address in partition.address_list:
       address_list.append('/'.join([address['addr'], address['netmask']]))
     computer_definition.set(section, 'address', ' '.join(address_list))
+    computer_definition.set(section, 'ipv6_range', partition.ipv6_range['network'])
     computer_definition.set(section, 'user', partition.user.name)
     computer_definition.set(section, 'network_interface', partition.tap.name)
     computer_definition.set(section, 'pathname', partition.reference)
@@ -1419,6 +1485,7 @@ class FormatConfig(object):
   alter_network = 'True' # modifiable by cmdline
   interface_name = None
   ipv6_interface = None
+  partition_has_ipv6_range = True
   create_tap = True
   create_tun = False
   tap_base_name = None
@@ -1483,7 +1550,7 @@ class FormatConfig(object):
         raise UsageError(message)
 
     # Convert strings to booleans
-    for option in ['alter_network', 'alter_user', 'create_tap', 'create_tun', 'tap_ipv6']:
+    for option in ['alter_network', 'alter_user', 'partition_has_ipv6_range', 'create_tap', 'create_tun', 'tap_ipv6']:
       attr = getattr(self, option)
       if isinstance(attr, str):
         if attr.lower() == 'true':

slapos/slap/standalone.py

@@ -59,11 +59,23 @@ from .interface.slap import IRequester
 from ..grid.slapgrid import SLAPGRID_PROMISE_FAIL
 
 from .slap import slap
-from ..util import dumps, rmtree
+from ..util import dumps, rmtree, getPartitionIpv6Addr, getPartitionIpv6Range
 
 from ..grid.svcbackend import getSupervisorRPC
 from ..grid.svcbackend import _getSupervisordSocketPath
 
+def _getPartitionIpv6(ipv6_address, i):
+  # returns (single_ipv6_address, ipv6_range) for a partition
+  # ipv6_address can be either a range or a single IPv6 address (with no /)
+  if '/' in ipv6_address:
+    addr,netmask = ipv6_address.split('/')
+    single_ipv6_address = getPartitionIpv6Addr({'addr':addr, 'netmask':int(netmask)}, i)['addr']
+    ipv6_range = getPartitionIpv6Range({'addr':addr, 'netmask':int(netmask)}, i)
+  else:
+    ipv6_range = None
+    single_ipv6_address = ipv6_address
+  return (single_ipv6_address, ipv6_range)
+
 
 @zope.interface.implementer(IException)
 class SlapOSNodeCommandError(Exception):
@@ -287,9 +299,7 @@ class SlapformatDefinitionWriter(ConfigWriter):
   """
   def writeConfig(self, path):
     ipv4 = self._standalone_slapos._ipv4_address
-    ipv6 = self._standalone_slapos._ipv6_address
     ipv4_cidr = ipv4 + '/255.255.255.255' if ipv4 else ''
-    ipv6_cidr = ipv6 + '/64' if ipv6 else ''
     user = pwd.getpwuid(os.getuid()).pw_name
     partition_base_name = self._standalone_slapos._partition_base_name
     with open(path, 'w') as f:
@@ -300,11 +310,15 @@ class SlapformatDefinitionWriter(ConfigWriter):
               address = {ipv4_cidr}\n
       """).format(**locals()))
       for i in range(self._standalone_slapos._partition_count):
+        print(i)
+        single_ipv6_address, ipv6_range = _getPartitionIpv6(self._standalone_slapos._ipv6_address, i)
+        ipv6_range_network= '{addr}/{netmask}'.format(**ipv6_range)
         f.write(
             textwrap.dedent(
                 """
                 [partition_{i}]
-                address = {ipv6_cidr} {ipv4_cidr}
+                address = {single_ipv6_address}/128 {ipv4_cidr}
+                ipv6_range = {ipv6_range_network}
                 pathname = {partition_base_name}{i}
                 user = {user}
                 network_interface =\n
@@ -594,8 +608,12 @@ class StandaloneSlapOS(object):
       partition_base_name="slappart"):
     """Creates `partition_count` partitions.
 
-    All partitions have the same `ipv4_address` and `ipv6_address` and
-    use the current system user.
+    All partitions have the same `ipv4_address` and use the current system
+    user.
+
+    `ipv6_address` can be a single address (in this case all partitions have
+    the same address) or a range in the form IPV6/CIDR (in this case each
+    partition has a subrange).
 
     When calling this a second time with a lower `partition_count` or with
     different `partition_base_name` will delete existing partitions.
@@ -628,6 +646,7 @@ class StandaloneSlapOS(object):
       if not (os.path.exists(partition_path)):
         os.mkdir(partition_path)
       os.chmod(partition_path, 0o750)
+      single_ipv6_address, ipv6_range = _getPartitionIpv6(ipv6_address, i)
       partition_list.append({
           'address_list': [
               {
@@ -635,10 +654,11 @@ class StandaloneSlapOS(object):
                   'netmask': '255.255.255.255'
               },
               {
-                  'addr': ipv6_address,
+                  'addr': single_ipv6_address,
                   'netmask': 'ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff'
               },
           ],
+          'ipv6_range' : ipv6_range,
           'path': partition_path,
           'reference': partition_reference,
           'tap': {

slapos/util.py

@@ -199,6 +199,69 @@ def ipv6FromBin(ip, suffix=''):
   return socket.inet_ntop(socket.AF_INET6,
     struct.pack('>QQ', int(ip[:64], 2), int(ip[64:], 2)))
 
+def getPartitionIpv6Addr(ipv6_range, partition_index):
+  """
+  from a IPv6 range in the form
+  {
+    'addr' : addr,
+    'natmask' : CIDR
+  }
+  returns the IPv6 addr
+  addr::(partition_index+2) (address 1 is is used by re6st)
+  """
+  addr = ipv6_range['addr']
+  netmask = ipv6_range['netmask']
+  prefix = binFromIpv6(addr)[:netmask]
+  return dict(addr = ipv6FromBin(prefix + bin(partition_index+2)[2:].zfill(128 - netmask)), netmask = netmask)
+
+def getPartitionIpv6Range(ipv6_range, partition_index):
+  """
+  from a IPv6 range in the form
+  {
+    'addr' : addr,
+    'natmask' : CIDR
+  }
+  returns the IPv6 range
+  {
+    'addr' : addr:(partition_index+1)
+    'netmask : CIDR+16
+  }
+  """
+  addr = ipv6_range['addr']
+  netmask = ipv6_range['netmask']
+  prefix = binFromIpv6(addr)[:netmask]
+  # we generate a subnetwork for the partition
+  # the subnetwork has 16 bits more than our IPv6 range
+  # make sure we have at least 2 IPs in the subnetwork
+  netmask += 16
+  if netmask >= 128:
+    raise ValueError('The IPv6 range has netmask {} which is too big for generating IPv6 range for partitions.'.format(netmask))
+  return dict(addr = ipv6FromBin(prefix + bin(partition_index+1)[2:].zfill(16) + '0' * (128 - netmask)), netmask=netmask)
+
+def getTapIpv6Range(ipv6_range, partition_index):
+  """
+  from a IPv6 range in the form
+  {
+    'addr' : addr,
+    'natmask' : CIDR
+  }
+  returns the IPv6 range
+  {
+    'addr' : addr:(2^15 + partition_index+1)
+    'netmask : CIDR+16
+  }
+  """
+  addr = ipv6_range['addr']
+  netmask = ipv6_range['netmask']
+  prefix = binFromIpv6(addr)[:netmask]
+  # we generate a subnetwork for the partition
+  # the subnetwork has 16 bits more than our IPv6 range
+  # make sure we have at least 2 IPs in the subnetwork
+  netmask += 16
+  if netmask >= 128:
+    raise ValueError('The IPv6 range has netmask {} which is too big for generating IPv6 range for partitions.'.format(netmask))
+  return dict(addr = ipv6FromBin(prefix + bin(2^15 + partition_index+1)[2:].zfill(16) + '0' * (128 - netmask)), netmask=netmask)
+
 def lenNetmaskIpv6(netmask):
   """Convert string represented netmask to its integer prefix"""
   # Since version 0.10.7 of netifaces, the netmask is something like "ffff::/16",
@@ -209,6 +272,10 @@ def lenNetmaskIpv6(netmask):
   except ValueError:
     return netaddr.IPNetwork(netmask).prefixlen
 
+def netmaskFromLenIPv6(netmask_len):
+  """ opposite of lenNetmaskIpv6"""
+  return ipv6FromBin('1' * netmask_len)
+
 # Used for Python 2-3 compatibility
 if str is bytes:
   bytes2str = str2bytes = lambda s: s