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

2012-12-05 18:41:06 +02:00 · 2012-12-05 18:41:06 +02:00 · a81ac2150d
commit a81ac2150d
parent 2107b9a650
5 changed files with 324 additions and 171 deletions
--- a/src/inet.c
+++ b/src/inet.c
@ -231,45 +231,31 @@ static int inet_global_gethostname(lua_State *L)
 \*-------------------------------------------------------------------------*/
 int inet_meth_getpeername(lua_State *L, p_socket ps, int family)
 {
-    switch (family) {
-        case PF_INET: {
-            struct sockaddr_in peer;
-            socklen_t peer_len = sizeof(peer);
-            char name[INET_ADDRSTRLEN];
-            if (getpeername(*ps, (SA *) &peer, &peer_len) < 0) {
-                lua_pushnil(L);
-                lua_pushstring(L, socket_strerror(errno));
-                return 2;
-            } else {
-                inet_ntop(family, &peer.sin_addr, name, sizeof(name));
-                lua_pushstring(L, name); 
-                lua_pushnumber(L, ntohs(peer.sin_port));
-                lua_pushliteral(L, "inet");
-                return 3;
-            }
-        }
-        case PF_INET6: {
-            struct sockaddr_in6 peer;
-            socklen_t peer_len = sizeof(peer);
-            char name[INET6_ADDRSTRLEN];
-            if (getpeername(*ps, (SA *) &peer, &peer_len) < 0) {
-                lua_pushnil(L);
-                lua_pushstring(L, socket_strerror(errno));
-                return 2;
-            } else {
-                inet_ntop(family, &peer.sin6_addr, name, sizeof(name));
-                lua_pushstring(L, name); 
-                lua_pushnumber(L, ntohs(peer.sin6_port));
-                lua_pushliteral(L, "inet6");
-                return 3;
-            }
-            return 2;
-        }
-        default:
-            lua_pushnil(L);
-            lua_pushfstring(L, "unknown family %d", family);
-            return 2;
-    }
+  int err;
+  struct sockaddr_storage peer;
+  socklen_t peer_len = sizeof(peer);
+  char name[INET6_ADDRSTRLEN];
+  char port[6]; /* 65535 = 5 bytes + 0 to terminate it */
+  if (getpeername(*ps, (SA *) &peer, &peer_len) < 0) {
+    lua_pushnil(L);
+    lua_pushstring(L, socket_strerror(errno));
+    return 2;
+  }
+  if ((err=getnameinfo((struct sockaddr *)&peer, peer_len,
+                       name, INET6_ADDRSTRLEN,
+                       port, 6,
+                       NI_NUMERICHOST | NI_NUMERICSERV))) {
+    lua_pushnil(L);
+    lua_pushstring(L, gai_strerror(err));
+    return 2;
+  }
+  lua_pushstring(L, name);
+  lua_pushstring(L, port);
+  if (family == PF_INET)
+    lua_pushliteral(L, "inet");
+  else
+    lua_pushliteral(L, "inet6");
+  return 3;
 }

 /*-------------------------------------------------------------------------*\
@ -277,44 +263,31 @@ int inet_meth_getpeername(lua_State *L, p_socket ps, int family)
 \*-------------------------------------------------------------------------*/
 int inet_meth_getsockname(lua_State *L, p_socket ps, int family)
 {
-    switch (family) {
-        case PF_INET: {
-            struct sockaddr_in local;
-            socklen_t local_len = sizeof(local);
-            char name[INET_ADDRSTRLEN];
-            if (getsockname(*ps, (SA *) &local, &local_len) < 0) {
-                lua_pushnil(L);
-                lua_pushstring(L, socket_strerror(errno));
-                return 2;
-            } else {
-                inet_ntop(family, &local.sin_addr, name, sizeof(name));
-                lua_pushstring(L, name); 
-                lua_pushnumber(L, ntohs(local.sin_port));
-                lua_pushliteral(L, "inet");
-                return 3;
-            }
-        }
-        case PF_INET6: {
-            struct sockaddr_in6 local;
-            socklen_t local_len = sizeof(local);
-            char name[INET6_ADDRSTRLEN];
-            if (getsockname(*ps, (SA *) &local, &local_len) < 0) {
-                lua_pushnil(L);
-                lua_pushstring(L, socket_strerror(errno));
-                return 2;
-            } else {
-                inet_ntop(family, &local.sin6_addr, name, sizeof(name));
-                lua_pushstring(L, name); 
-                lua_pushnumber(L, ntohs(local.sin6_port));
-                lua_pushliteral(L, "inet6");
-                return 3;
-            }
-        }
-        default:
-            lua_pushnil(L);
-            lua_pushfstring(L, "unknown family %d", family);
-            return 2;
-    }
+  int err;
+  struct sockaddr_storage peer;
+  socklen_t peer_len = sizeof(peer);
+  char name[INET6_ADDRSTRLEN];
+  char port[6]; /* 65535 = 5 bytes + 0 to terminate it */
+  if (getsockname(*ps, (SA *) &peer, &peer_len) < 0) {
+    lua_pushnil(L);
+    lua_pushstring(L, socket_strerror(errno));
+    return 2;
+  }
+  if ((err=getnameinfo((struct sockaddr *)&peer, peer_len,
+                       name, INET6_ADDRSTRLEN,
+                       port, 6,
+                       NI_NUMERICHOST | NI_NUMERICSERV))) {
+    lua_pushnil(L);
+    lua_pushstring(L, gai_strerror(err));
+    return 2;
+  }
+  lua_pushstring(L, name);
+  lua_pushstring(L, port);
+  if (family == PF_INET)
+    lua_pushliteral(L, "inet");
+  else
+    lua_pushliteral(L, "inet6");
+  return 3;
 }

 /*=========================================================================*\
--- a/src/options.c
+++ b/src/options.c
@ -14,8 +14,11 @@
 * Internal functions prototypes
 \*=========================================================================*/
 static int opt_setmembership(lua_State *L, p_socket ps, int level, int name);
+static int opt_ip6_setmembership(lua_State *L, p_socket ps, int level, int name);
 static int opt_setboolean(lua_State *L, p_socket ps, int level, int name);
 static int opt_getboolean(lua_State *L, p_socket ps, int level, int name);
+static int opt_setint(lua_State *L, p_socket ps, int level, int name);
+static int opt_getint(lua_State *L, p_socket ps, int level, int name);
 static int opt_set(lua_State *L, p_socket ps, int level, int name, 
        void *val, int len);
 static int opt_get(lua_State *L, p_socket ps, int level, int name, 
@ -106,6 +109,26 @@ int opt_set_broadcast(lua_State *L, p_socket ps)
    return opt_setboolean(L, ps, SOL_SOCKET, SO_BROADCAST);
 }

+int opt_set_ip6_unicast_hops(lua_State *L, p_socket ps)
+{
+  return opt_setint(L, ps, IPPROTO_IPV6, IPV6_UNICAST_HOPS);
+}
+
+int opt_get_ip6_unicast_hops(lua_State *L, p_socket ps)
+{
+  return opt_getint(L, ps, IPPROTO_IPV6, IPV6_UNICAST_HOPS);
+}
+
+int opt_set_ip6_multicast_hops(lua_State *L, p_socket ps)
+{
+  return opt_setint(L, ps, IPPROTO_IPV6, IPV6_MULTICAST_HOPS);
+}
+
+int opt_get_ip6_multicast_hops(lua_State *L, p_socket ps)
+{
+  return opt_getint(L, ps, IPPROTO_IPV6, IPV6_MULTICAST_HOPS);
+}
+
 int opt_set_ip_multicast_loop(lua_State *L, p_socket ps)
 {
    return opt_setboolean(L, ps, IPPROTO_IP, IP_MULTICAST_LOOP);
@ -116,6 +139,16 @@ int opt_get_ip_multicast_loop(lua_State *L, p_socket ps)
    return opt_getboolean(L, ps, IPPROTO_IP, IP_MULTICAST_LOOP);
 }

+int opt_set_ip6_multicast_loop(lua_State *L, p_socket ps)
+{
+    return opt_setboolean(L, ps, IPPROTO_IPV6, IPV6_MULTICAST_LOOP);
+}
+
+int opt_get_ip6_multicast_loop(lua_State *L, p_socket ps)
+{
+    return opt_getboolean(L, ps, IPPROTO_IPV6, IPV6_MULTICAST_LOOP);
+}
+
 int opt_set_linger(lua_State *L, p_socket ps)
 {
    struct linger li;                      /* obj, name, table */
@ -150,9 +183,7 @@ int opt_get_linger(lua_State *L, p_socket ps)

 int opt_set_ip_multicast_ttl(lua_State *L, p_socket ps)
 {
-    int val = (int) luaL_checknumber(L, 3);    /* obj, name, int */
-    return opt_set(L, ps, IPPROTO_IP, IP_MULTICAST_TTL, 
-        (char *) &val, sizeof(val));
+    return opt_setint(L, ps, IPPROTO_IP, IP_MULTICAST_TTL);
 }

 int opt_set_ip_multicast_if(lua_State *L, p_socket ps)
@ -179,6 +210,8 @@ int opt_get_ip_multicast_if(lua_State *L, p_socket ps)
    return 1;
 }

+
+
 int opt_set_ip_add_membership(lua_State *L, p_socket ps)
 {
    return opt_setmembership(L, ps, IPPROTO_IP, IP_ADD_MEMBERSHIP);
@ -189,6 +222,21 @@ int opt_set_ip_drop_membersip(lua_State *L, p_socket ps)
    return opt_setmembership(L, ps, IPPROTO_IP, IP_DROP_MEMBERSHIP);
 }

+int opt_set_ip6_add_membership(lua_State *L, p_socket ps)
+{
+    return opt_ip6_setmembership(L, ps, IPPROTO_IPV6, IPV6_ADD_MEMBERSHIP);
+}
+
+int opt_set_ip6_drop_membersip(lua_State *L, p_socket ps)
+{
+    return opt_ip6_setmembership(L, ps, IPPROTO_IPV6, IPV6_DROP_MEMBERSHIP);
+}
+
+int opt_get_ip6_v6only(lua_State *L, p_socket ps)
+{
+    return opt_getboolean(L, ps, IPPROTO_IPV6, IPV6_V6ONLY);
+}
+
 int opt_set_ip6_v6only(lua_State *L, p_socket ps)
 {
    return opt_setboolean(L, ps, IPPROTO_IPV6, IPV6_V6ONLY);
@ -218,6 +266,31 @@ static int opt_setmembership(lua_State *L, p_socket ps, int level, int name)
    return opt_set(L, ps, level, name, (char *) &val, sizeof(val));
 }

+static int opt_ip6_setmembership(lua_State *L, p_socket ps, int level, int name)
+{
+    struct ipv6_mreq val;                   /* obj, opt-name, table */
+    memset(&val, 0, sizeof(val));
+    if (!lua_istable(L, 3)) auxiliar_typeerror(L,3,lua_typename(L, LUA_TTABLE));
+    lua_pushstring(L, "multiaddr");
+    lua_gettable(L, 3);
+    if (!lua_isstring(L, -1)) 
+        luaL_argerror(L, 3, "string 'multiaddr' field expected");
+    if (!inet_pton(AF_INET6, lua_tostring(L, -1), &val.ipv6mr_multiaddr)) 
+        luaL_argerror(L, 3, "invalid 'multiaddr' ip address");
+    lua_pushstring(L, "interface");
+    lua_gettable(L, 3);
+    /* By default we listen to all interfaces. However, interface= can
+       override it. */
+    if (!lua_isnil(L, -1))
+      {
+        if (!lua_isnumber(L, -1)) 
+          luaL_argerror(L, 3, "string 'interface' field expected");
+        /* XXX - support non-numeric interface specification? */
+      }
+    val.ipv6mr_interface = lua_tonumber(L, -1);
+    return opt_set(L, ps, level, name, (char *) &val, sizeof(val));
+}
+
 static 
 int opt_get(lua_State *L, p_socket ps, int level, int name, void *val, int* len)
 {
@ -260,3 +333,19 @@ static int opt_setboolean(lua_State *L, p_socket ps, int level, int name)
    return opt_set(L, ps, level, name, (char *) &val, sizeof(val));
 }

+static int opt_getint(lua_State *L, p_socket ps, int level, int name)
+{
+    int val = 0;
+    int len = sizeof(val);
+    int err = opt_get(L, ps, level, name, (char *) &val, &len);
+    if (err)
+        return err;
+    lua_pushnumber(L, val);
+    return 1;
+}
+
+static int opt_setint(lua_State *L, p_socket ps, int level, int name)
+{
+    int val = (int) lua_tonumber(L, 3);             /* obj, name, int */
+    return opt_set(L, ps, level, name, (char *) &val, sizeof(val));
+}
--- a/src/options.h
+++ b/src/options.h
@ -32,6 +32,11 @@ int opt_set_ip_multicast_ttl(lua_State *L, p_socket ps);
 int opt_set_ip_multicast_loop(lua_State *L, p_socket ps);
 int opt_set_ip_add_membership(lua_State *L, p_socket ps);
 int opt_set_ip_drop_membersip(lua_State *L, p_socket ps);
+int opt_set_ip6_unicast_hops(lua_State *L, p_socket ps);
+int opt_set_ip6_multicast_hops(lua_State *L, p_socket ps);
+int opt_set_ip6_multicast_loop(lua_State *L, p_socket ps);
+int opt_set_ip6_add_membership(lua_State *L, p_socket ps);
+int opt_set_ip6_drop_membersip(lua_State *L, p_socket ps);
 int opt_set_ip6_v6only(lua_State *L, p_socket ps);

 /* supported options for getoption */
@ -42,6 +47,10 @@ int opt_get_linger(lua_State *L, p_socket ps);
 int opt_get_reuseaddr(lua_State *L, p_socket ps);
 int opt_get_ip_multicast_loop(lua_State *L, p_socket ps);
 int opt_get_ip_multicast_if(lua_State *L, p_socket ps);
+int opt_get_ip6_multicast_loop(lua_State *L, p_socket ps);
+int opt_get_ip6_multicast_hops(lua_State *L, p_socket ps);
+int opt_get_ip6_unicast_hops(lua_State *L, p_socket ps);
+int opt_get_ip6_v6only(lua_State *L, p_socket ps);

 /* invokes the appropriate option handler */
 int opt_meth_setoption(lua_State *L, p_opt opt, p_socket ps);
--- a/src/udp.c
+++ b/src/udp.c
@ -77,6 +77,11 @@ static t_opt optset[] = {
    {"ip-multicast-loop",  opt_set_ip_multicast_loop},
    {"ip-add-membership",  opt_set_ip_add_membership},
    {"ip-drop-membership", opt_set_ip_drop_membersip},
+    {"ipv6-unicast-hops",  opt_set_ip6_unicast_hops},
+    {"ipv6-multicast-hops",opt_set_ip6_unicast_hops},
+    {"ipv6-multicast-loop",  opt_set_ip6_multicast_loop},
+    {"ipv6-add-membership", opt_set_ip6_add_membership},
+    {"ipv6-drop-membership", opt_set_ip6_drop_membersip},
    {"ipv6-v6only",        opt_set_ip6_v6only},
    {NULL,                 NULL}
 };
@ -85,6 +90,10 @@ static t_opt optset[] = {
 static t_opt optget[] = {
    {"ip-multicast-if",    opt_get_ip_multicast_if},
    {"ip-multicast-loop",  opt_get_ip_multicast_loop},
+    {"ipv6-unicast-hops",  opt_get_ip6_unicast_hops},
+    {"ipv6-multicast-hops",opt_get_ip6_unicast_hops},
+    {"ipv6-multicast-loop",opt_get_ip6_multicast_loop},
+    {"ipv6-v6only",        opt_get_ip6_v6only},
    {NULL,                 NULL}
 };

@ -151,39 +160,25 @@ static int meth_sendto(lua_State *L) {
    size_t count, sent = 0;
    const char *data = luaL_checklstring(L, 2, &count);
    const char *ip = luaL_checkstring(L, 3);
-    unsigned short port = (unsigned short) luaL_checknumber(L, 4);
+    /* unsigned short port = (unsigned short) luaL_checknumber(L, 4); */
    p_timeout tm = &udp->tm;
    int err;
-    switch (udp->family) {
-	case PF_INET: {
-	    struct sockaddr_in addr;
-	    memset(&addr, 0, sizeof(addr));
-	    if (!inet_pton(AF_INET, ip, &addr.sin_addr))
-		luaL_argerror(L, 3, "invalid ip address");
-	    addr.sin_family = AF_INET;
-	    addr.sin_port = htons(port);
-	    timeout_markstart(tm);
-	    err = socket_sendto(&udp->sock, data, count, &sent,
-		    (SA *) &addr, sizeof(addr), tm);
-	    break;
-	}
-	case PF_INET6: {
-	    struct sockaddr_in6 addr;
-	    memset(&addr, 0, sizeof(addr));
-	    if (!inet_pton(AF_INET6, ip, &addr.sin6_addr))
-		luaL_argerror(L, 3, "invalid ip address");
-	    addr.sin6_family = AF_INET6;
-	    addr.sin6_port = htons(port);
-	    timeout_markstart(tm);
-	    err = socket_sendto(&udp->sock, data, count, &sent,
-		    (SA *) &addr, sizeof(addr), tm);
-	    break;
-	}
-	default:
-            lua_pushnil(L);
-            lua_pushfstring(L, "unknown family %d", udp->family);
-            return 2;
-    }
+    struct addrinfo aihint;
+    struct addrinfo *ai;
+
+    memset(&aihint, 0, sizeof(aihint));
+    aihint.ai_family = udp->family;
+    aihint.ai_socktype = SOCK_DGRAM;
+    if ((err = getaddrinfo(ip, lua_tostring(L, 4), &aihint, &ai)))
+      {
+        lua_pushnil(L);
+        lua_pushstring(L, udp_strerror(err));
+        return 2;
+      }
+    timeout_markstart(tm);
+    err = socket_sendto(&udp->sock, data, count, &sent,
+                        ai->ai_addr, ai->ai_addrlen, tm);
+    freeaddrinfo(ai);
    if (err != IO_DONE) {
        lua_pushnil(L);
        lua_pushstring(L, udp_strerror(err));
@ -220,69 +215,40 @@ static int meth_receive(lua_State *L) {
 /*-------------------------------------------------------------------------*\
 * Receives data and sender from a UDP socket
 \*-------------------------------------------------------------------------*/
-static int meth_receivefrom(lua_State *L) {
-    p_udp udp = (p_udp) auxiliar_checkclass(L, "udp{unconnected}", 1);
-    char buffer[UDP_DATAGRAMSIZE];
-    size_t got, count = (size_t) luaL_optnumber(L, 2, sizeof(buffer));
-    int err;
-    p_timeout tm = &udp->tm;
-    timeout_markstart(tm);
-    count = MIN(count, sizeof(buffer));
-    switch (udp->family) {
-	case PF_INET: {
-	    struct sockaddr_in addr;
-	    socklen_t addr_len = sizeof(addr);
-	    err = socket_recvfrom(&udp->sock, buffer, count, &got,
-		    (SA *) &addr, &addr_len, tm);
-	    /* Unlike TCP, recv() of zero is not closed, but a zero-length packet. */
-	    if (err == IO_CLOSED)
-		err = IO_DONE;
-	    if (err == IO_DONE) {
-		char addrstr[INET_ADDRSTRLEN];
-		lua_pushlstring(L, buffer, got);
-		if (!inet_ntop(AF_INET, &addr.sin_addr,
-			addrstr, sizeof(addrstr))) {
-		    lua_pushnil(L);
-		    lua_pushstring(L, "invalid source address");
-		    return 2;
-		}
-		lua_pushstring(L, addrstr);
-		lua_pushnumber(L, ntohs(addr.sin_port));
-		return 3;
-	    }
-	    break;
-	}
-	case PF_INET6: {
-	    struct sockaddr_in6 addr;
-	    socklen_t addr_len = sizeof(addr);
-	    err = socket_recvfrom(&udp->sock, buffer, count, &got,
-		    (SA *) &addr, &addr_len, tm);
-	    /* Unlike TCP, recv() of zero is not closed, but a zero-length packet. */
-	    if (err == IO_CLOSED)
-		err = IO_DONE;
-	    if (err == IO_DONE) {
-		char addrstr[INET6_ADDRSTRLEN];
-		lua_pushlstring(L, buffer, got);
-		if (!inet_ntop(AF_INET6, &addr.sin6_addr,
-			addrstr, sizeof(addrstr))) {
-		    lua_pushnil(L);
-		    lua_pushstring(L, "invalid source address");
-		    return 2;
-		}
-		lua_pushstring(L, addrstr);
-		lua_pushnumber(L, ntohs(addr.sin6_port));
-		return 3;
-	    }
-	    break;
-	}
-    default:
-        lua_pushnil(L);
-        lua_pushfstring(L, "unknown family %d", udp->family);
-        return 2;
-    }
+static int meth_receivefrom(lua_State *L)
+{
+  p_udp udp = (p_udp) auxiliar_checkclass(L, "udp{unconnected}", 1);
+  char buffer[UDP_DATAGRAMSIZE];
+  size_t got, count = (size_t) luaL_optnumber(L, 2, sizeof(buffer));
+  int err;
+  p_timeout tm = &udp->tm;
+  struct sockaddr_storage addr;
+  socklen_t addr_len = sizeof(addr);
+  char addrstr[INET6_ADDRSTRLEN];
+  char portstr[6];
+  timeout_markstart(tm);
+  count = MIN(count, sizeof(buffer));
+  err = socket_recvfrom(&udp->sock, buffer, count, &got,
+                        (SA *) &addr, &addr_len, tm);
+  /* Unlike TCP, recv() of zero is not closed, but a zero-length packet. */
+  if (err == IO_CLOSED)
+    err = IO_DONE;
+  if (err != IO_DONE) {
    lua_pushnil(L);
    lua_pushstring(L, udp_strerror(err));
    return 2;
+  }
+  if ((err = getnameinfo((struct sockaddr *)&addr, addr_len,
+                         addrstr, INET6_ADDRSTRLEN,
+                         portstr, 6,
+                         NI_NUMERICHOST | NI_NUMERICSERV))) {
+    lua_pushnil(L);
+    lua_pushstring(L, gai_strerror(err));
+    return 2;
+  }
+  lua_pushstring(L, addrstr);
+  lua_pushstring(L, portstr);
+  return 3;
 }

 /*-------------------------------------------------------------------------*\
--- a/test/ipv6mcasttest.lua
+++ b/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)
+
+