ipv4: New multicast-all socket option

After some discussion offline with Christoph Lameter and David Stevens
regarding multicast behaviour in Linux, I'm submitting a slightly
modified patch from the one Christoph submitted earlier.

This patch provides a new socket option IP_MULTICAST_ALL.

In this case, default behaviour is _unchanged_ from the current
Linux standard. The socket option is set by default to provide
original behaviour. Sockets wishing to receive data only from
multicast groups they join explicitly will need to clear this
socket option.

Signed-off-by: Nivedita Singhvi <niv@us.ibm.com>
Signed-off-by: Christoph Lameter<cl@linux.com>
Acked-by: David Stevens <dlstevens@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/in.h b/include/linux/in.h
index d60122a3a088..cf196da04ec9 100644
--- a/include/linux/in.h
+++ b/include/linux/in.h
@@ -107,6 +107,7 @@ struct in_addr {
 #define MCAST_JOIN_SOURCE_GROUP         46
 #define MCAST_LEAVE_SOURCE_GROUP        47
 #define MCAST_MSFILTER                  48
+#define IP_MULTICAST_ALL                49
 
 #define MCAST_EXCLUDE   0
 #define MCAST_INCLUDE   1