Converted code to use getaddrinfo/getnameinfo (available ~everywhere like *BSD, Linux, Windows at least), and added various ipv6 socket options' get+set.

test/ipv6mcasttest.lua

@@ -0,0 +1,116 @@
+#!/usr/bin/env lua
+-- -*-lua-*-
+--
+-- $Id: ipv6mcasttest.lua $
+--
+-- Author: Markus Stenberg <mstenber@cisco.com>
+--
+-- Copyright (c) 2012 cisco Systems, Inc.
+--
+-- Created:       Wed Dec  5 09:55:46 2012 mstenber
+-- Last modified: Wed Dec  5 18:33:09 2012 mstenber
+-- Edit time:     50 min
+--
+
+-- exercise the new IPv6 related functionality:
+
+-- join/leave IPv6 multicast group, send/receive IPv6 message using
+-- sendmsg/recvmsg API
+
+require 'socket'
+
+local mcast = 'ff02::fb'
+
+local port = 4242
+local ifname = 'eth2'
+--local ifname = 'lo' -- should not work - no multicast on lo in Linux?
+local testdata = 'foobar'
+
+function setup_socket(port)
+   local s = socket.udp6()
+   s:setoption('ipv6-v6only', true)
+   if port
+   then
+      s:setoption('reuseaddr', true)
+      --local r, err = s:setsockname('::1', port)
+      local r, err = s:setsockname('*', port)
+      assert(r, 'setsockname failed ' .. tostring(err))
+      --print("getsockname", s:getsockname())
+   end
+   assert(tostring(s):find("udp{unconnected}"))
+   return s
+end
+
+function setup_connected(host, port)
+   local c = setup_socket()
+   assert(host and port)
+   local r, err = c:setpeername(host, port)
+   assert(r, 'setpeername failed ' .. tostring(err))
+   --print('got from setpeername', r, err)
+   --print("getsockname", c:getsockname())
+   assert(tostring(c):find("udp{connected}"), 'not connected', tostring(c))
+   --print("getpeername", c:getpeername())
+   return c
+end
+
+function my_setoption(s, k, v)
+   local old = s:getoption(k)
+   print('before set', k, old)
+   local r, err = s:setoption(k, v)
+   assert(r, 'setoption failed ' .. tostring(err))
+   local new = s:getoption(k)
+   print('after set', k, new)
+   assert(v == new)
+end
+
+-- specific interface
+--local ifindex = socket.iface.nametoindex(ifname)
+
+-- all interfaces
+local ifindex = nil
+
+local s = setup_socket(port)
+
+local mct = {multiaddr=mcast, interface=ifindex}
+local r, err = s:setoption('ipv6-drop-membership', mct)
+-- don't check result - it may or may not fail
+local r, err = s:setoption('ipv6-add-membership', mct)
+assert(r, 'ipv6-add-membership failed', err)
+
+--local c = setup_connected(mcast .. '%lo', port)
+--c:send('foo')
+local c = setup_socket()
+
+-- this seems to be the default anyway?
+my_setoption(c, 'ipv6-unicast-hops', 255)
+my_setoption(c, 'ipv6-multicast-loop', true)
+my_setoption(c, 'ipv6-multicast-hops', 255)
+my_setoption(s, 'ipv6-multicast-hops', 255)
+
+local r, err = c:sendto(testdata, mcast .. '%' .. ifname, port)
+assert(r, 'sendto failed')
+
+-- make sure sending both to mcast address, and link-local
+-- address on the chosen interface works
+local r, err = c:sendto(testdata, mcast .. '%' .. ifname, port)
+assert(r, 'sendto failed (mcast)')
+
+local data, host, port = s:receivefrom()
+assert(data)
+print('recvfrom', host, port)
+
+-- make sure we can send stuff back to link-local addr as well'
+local r, err = s:sendto(testdata, host, port)
+assert(r, 'sendto failed (ll)')
+
+-- and it is received too
+local data, host, port = c:receivefrom()
+assert(data)
+print('recvfrom', host, port)
+
+-- now, finally, we can get rid of mcast group
+local r, err = s:setoption('ipv6-drop-membership', mct)
+assert(r, 'ipv6-drop-membership failed', err)
+--local c = setup_connected(port)
+
+