[src/trunk]: src/tests/net/mcast Explain a bit more what's going on with the ...

[christos <christos%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/807dcab3b6c8
branches:  trunk
changeset: 332947:807dcab3b6c8
user:      christos <christos%NetBSD.org@localhost>
date:      Sun Oct 12 14:53:46 2014 +0000

description:
Explain a bit more what's going on with the multicast setsockopts.

diffstat:

 tests/net/mcast/t_mcast.c |  9 +++++++--
 1 files changed, 7 insertions(+), 2 deletions(-)

diffs (38 lines):

diff -r 831361d32ce0 -r 807dcab3b6c8 tests/net/mcast/t_mcast.c
--- a/tests/net/mcast/t_mcast.c Sun Oct 12 14:06:18 2014 +0000
+++ b/tests/net/mcast/t_mcast.c Sun Oct 12 14:53:46 2014 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: t_mcast.c,v 1.2 2014/10/12 13:48:25 christos Exp $     */
+/*     $NetBSD: t_mcast.c,v 1.3 2014/10/12 14:53:46 christos Exp $     */
 
 /*-
  * Copyright (c) 2014 The NetBSD Foundation, Inc.
@@ -29,7 +29,7 @@
  * POSSIBILITY OF SUCH DAMAGE.
  */
 #include <sys/cdefs.h>
-__RCSID("$NetBSD: t_mcast.c,v 1.2 2014/10/12 13:48:25 christos Exp $");
+__RCSID("$NetBSD: t_mcast.c,v 1.3 2014/10/12 14:53:46 christos Exp $");
 
 #include <sys/types.h>
 #include <sys/socket.h>
@@ -90,7 +90,11 @@
                    &m4, sizeof(m4));
        case AF_INET6:
                s6 = (void *)ai->ai_addr;
+#if defined(__linux__) || defined(__NetBSD__)
                // XXX: Both linux and we do this thing wrong...
+               // It is just difficult to make the regular IPv6 multicast
+               // calls to work with mapped addresses because the code is
+               // not structured properly. MacOS/X works properly.
                if (IN6_IS_ADDR_V4MAPPED(&s6->sin6_addr)) {
                        memcpy(&m4.imr_multiaddr, &s6->sin6_addr.s6_addr[12],
                            sizeof(m4.imr_multiaddr));
@@ -98,6 +102,7 @@
                        return setsockopt(s, IPPROTO_IP, IP_ADD_MEMBERSHIP,
                            &m4, sizeof(m4));
                }
+#endif
                assert(sizeof(*s6) == ai->ai_addrlen);
                memset(&m6, 0, sizeof(m6));
                m6.ipv6mr_interface = 0;