pm_v6_nh.lua

#!/usr/bin/env lua
-- -*-lua-*-
--
-- $Id: pm_v6_nh.lua $
--
-- Author: Markus Stenberg <markus stenberg@iki.fi>
--
-- Copyright (c) 2012 cisco Systems, Inc.
--
-- Created:       Thu Nov  8 08:10:48 2012 mstenber
-- Last modified: Mon Sep 30 17:41:05 2013 mstenber
-- Edit time:     28 min
--

-- pm_v6_nh is responsible for maintaining the structure of the pm.nh,
-- which is then used by pm_v6_rule to as things change over time

-- novel thing about this is that it runs in tick's, and not otherwise

require 'pm_handler'
require 'linux_if'
require 'pm_v6_rule'

module(..., package.seeall)

pm_v6_nh = pm_handler.pm_handler_with_pa:new_subclass{class='pm_v6_nh', nh={}}

function pm_v6_nh:calculate_nh()
   -- if we don't have external links, not interested (only external
   -- ones matter)
   local nh = mst.multimap:new{}
   local ext = self.usp:get_external_if_set()
   self:d('calculate_nh got ext ifs', ext)
   if ext and mst.table_count(ext) > 0
   then
      self:d('external interfaces', ext)

      -- what we do is we recreate the pm.nh every time. however, we
      -- emit the changed signal if and only if something changes (see
      -- below)
      self:a(self.shell)
      for i, o in ipairs(linux_if.get_ip6_routes(self.shell))
      do
         -- we ignore dead routes, and non-default ones
         self:d('got', o)
         if not o.dead and o.dst == 'default' 
            and o.metric ~= pm_v6_rule.DUMMY_METRIC
            and ext[o.dev]
         then
            self:d(' seems like valid default route, adding')
            nh:insert(o.dev, o.via)
         end
      end
   end
   return nh
end

function pm_v6_nh:tick()
   local nh = self:calculate_nh()

   if mst.repr_equal(nh, self.nh)
   then
      return
   end

   self:d('pm.nh updated', nh)

   self.nh = nh

   -- ok, a change => we change _pm.nh's method for propagating info
   -- along (could have been just no-args-signal and some other way of
   -- finding nh, but this is more readable - we provide the nh along,
   -- just like in other *_changeds that pm_core provides)
   self._pm.v6_nh_changed(nh)
end