pm_v6_rule.lua

#!/usr/bin/env lua
-- -*-lua-*-
--
-- $Id: pm_v6_rule.lua $
--
-- Author: Markus Stenberg <markus stenberg@iki.fi>
--
-- Copyright (c) 2012 cisco Systems, Inc.
--
-- Created:       Thu Nov  8 07:12:11 2012 mstenber
-- Last modified: Mon Sep 30 14:00:39 2013 mstenber
-- Edit time:     90 min
--

require 'pm_handler'

module(..., package.seeall)

DUMMY_METRIC=123456

-- we use the (128-length of prefix as preference on top of the base => 128)
RULE_PREF_MIN=1000
RULE_PREF_MAX=RULE_PREF_MIN + 128 
MAIN_TABLE='main'

local _phwp = pm_handler.pm_handler_with_pa

pm_v6_rule = _phwp:new_subclass{class='pm_v6_rule'}

function pm_v6_rule:init()
   _phwp.init(self)

   self.nh = {}
   self.applied_usp = {}
   self.defaults = mst.multimap:new{}

   local rt = linux_if.rule_table:new{shell=self.shell}
   self.rule_table = rt
   local vs = mst.validity_sync:new{t=self.rule_table, single=true}
   self.vsrt = vs
   local parent = self
   function vs:remove(rule)
      if rule.pref >= RULE_PREF_MIN and rule.pref <= RULE_PREF_MAX
      then
         rule:del(rt.shell)
         parent:removed_default(rule.table)
      end
      rt:remove(rule)
   end
   self:connect_method(self._pm.v6_nh_changed, self.nh_changed)
end

function pm_v6_rule:skv_changed(k, v)
   if k == elsa_pa.OSPF_RID_KEY
   then
      self.rid = v
      self:queue()
   end
end

function pm_v6_rule:nh_changed(nh)
   self.nh = nh
   self:queue()
end

function pm_v6_rule:removed_default(table)
   table = tonumber(table)
   -- if it wasn't numeric (or nil), probably not interesting
   if not table then return end
   -- get rid of the defaults that are associated with the table
   for i, v in ipairs(self.defaults[table] or {})
   do
      local nh, dev = unpack(v)
      self.shell(string.format('ip -6 route del default via %s dev %s metric ' .. tostring(DUMMY_METRIC), nh, dev))
   end
   self.defaults[table] = nil
end

function pm_v6_rule:added_default(table, nh, dev)
   table = tonumber(table)
   self:a(table, 'no table in added_default?', nh, dev)
   self.defaults:insert(table, {nh, dev})
   self.shell(string.format('ip -6 route add default via %s dev %s metric ' .. tostring(DUMMY_METRIC), nh, dev))
end

function pm_v6_rule:get_usp_nhl(usp)
   local r = self.nh[usp.ifname] or (usp.nh and {usp.nh}) or {}
   self:d('get_usp_nhl', usp, r)
   return r
end

function pm_v6_rule:get_usp_key(usp)
   local v = mst.repr{usp.prefix, usp.ifname, self:get_usp_nhl(usp)}
   self:d('usp key', v)
   return v
end

function pm_v6_rule:run()
   -- we have the internal rule_table object. we compare that against
   -- the state we have in skv for OSPF (pd changes should come via
   -- OSPF process, hopefully, to keep the dataflow consistent)

   -- refresh the state
   self.rule_table:parse()

   -- mark all rules non-valid 
   self.vsrt:clear_all_valid()

   -- we ignore all USPs without ifname + nh
   local usps = self.usp:get_ipv6()
   usps = usps:filter(function (usp) 
                         return usp.ifname 
                            and #self:get_usp_nhl(usp)>0 
                      end)
   for _, usp in ipairs(usps)
   do
      local sel = 'from ' .. usp.prefix
      local i1, i2, s = string.find(usp.prefix, '/(%d+)$')
      self:a('invalid prefix', usp.prefix)
      local bits = tonumber(s)
      local pref = RULE_PREF_MIN + 128 - bits
      local template = {sel=sel, pref=pref}
      self:d('looking for template', template)
      local o = self.rule_table:find(template)

      -- in this iteration, we don't care about USP that lack ifname
      local update_table = nil
      if o
      then
         local uspk = self:get_usp_key(usp)
         self.vsrt:set_valid(o)
         local old_uspk = self.applied_usp[usp.prefix]
         if old_uspk ~= uspk
         then
            -- in rule table, changed => refresh the table's contents
            -- (but keep the table)
            update_table = o.table
            self:d('contents changed', old_uspk, uspk, 
                   'updating table', update_table)
            if not update_table
            then
               -- treat as new, if we don't know/remember the table
               -- number any more
               o = nil
               self:d('no table specified?')

            end
         else
            self:d('contents did not change', uspk)
         end
      end
      if not o
      then
         self:d(' template not found')

         -- figure table number
         local table = self.rule_table:get_free_table()
         template.table = table

         local r = self.rule_table:add_rule(template)

         -- and add it 
         r:add(self.shell)

         update_table = table
      end
      if update_table
      then
         local table = update_table
         local nhl = self:get_usp_nhl(usp)
         local dev = usp.ifname

         -- store that it has been added/updated
         local uspk = self:get_usp_key(usp)
         self.applied_usp[usp.prefix] = uspk


         self:d('updating table', usp.prefix, table, dev, nhl)

         -- get rid of defaults, if any
         self:removed_default(table)
         
         -- and flush the table
         self.shell('ip -6 route flush table ' .. table)
         
         -- and add the default route to the table
         for i, nh in ipairs(nhl)
         do
            self.shell(string.format('ip -6 route add default via %s dev %s table %s',
                                     nh, dev, table))
            -- it should be there already if it's our own
            if usp.rid ~= self.rid
            then
               self:added_default(table, nh, dev)
            end
         end
      end
   end
   
   for _, usp in ipairs(usps)
   do
      -- to rules just point at main table => no content to care about
      local sel = 'from all to ' .. usp.prefix
      local pref = RULE_PREF_MIN
      local template = {sel=sel, pref=pref, table=MAIN_TABLE}
      local o = self.rule_table:find(template)
      if o
      then
         self.vsrt:set_valid(o)
      else
         self:d('unable to find local dst table reference', template)
         local r = self.rule_table:add_rule(template)
         r:add(self.shell)
      end
   end

   -- in rule table, not in OSPF => del
   self.vsrt:remove_all_invalid()

   return 1
end