Added if_* POSIX API wrappers under socket.iface.

test/ifacetest.lua

@@ -0,0 +1,27 @@
+#!/usr/bin/env lua
+-- -*-lua-*-
+--
+-- $Id: ifacetest.lua $
+--
+-- Author: Markus Stenberg <fingon@iki.fi>
+--
+-- Copyright (c) 2012 cisco Systems, Inc.
+--
+-- Created:       Wed Dec  5 09:42:12 2012 mstenber
+-- Last modified: Wed Dec  5 09:51:17 2012 mstenber
+-- Edit time:     3 min
+--
+
+local socket = require 'socket'
+local iface = socket.iface
+
+local a = iface.nameindex()
+assert(#a > 0)
+local o = a[1]
+assert(o.index)
+assert(o.name)
+assert(iface.nametoindex(o.name))
+assert(not iface.nametoindex('gargle'))
+assert(iface.indextoname(o.index))
+assert(not iface.indextoname(-123))
+