[IPV4]: multicast API "join" issues

1) Changes IP_ADD_SOURCE_MEMBERSHIP and MCAST_JOIN_SOURCE_GROUP to ignore
   EADDRINUSE errors on a "courtesy join" -- prior membership or not
   is ok for these.

2) Adds "leave group" equivalence of (INCLUDE, empty) filters in the 
   delta-based API. Without this, mixing delta-based API calls that
   end in an (INCLUDE, empty) filter would not allow a subsequent
   regular IP_ADD_MEMBERSHIP. It also frees socket buffer memory that
   isn't needed for both the multicast group record and source filter.

Signed-off-by: David L Stevens <dlstevens@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 0 deletions

diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index 111eb678cbac..e21ebe759907 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -1724,6 +1724,7 @@ int ip_mc_source(int add, int omode, struct sock *sk, struct
         struct in_device *in_dev = NULL;
         struct inet_sock *inet = inet_sk(sk);
         struct ip_sf_socklist *psl;
+        int leavegroup = 0;
         int i, j, rv;
 
         if (!MULTICAST(addr))
@@ -1775,6 +1776,12 @@ int ip_mc_source(int add, int omode, struct sock *sk, struct
                 if (rv)         /* source not found */
                         goto done;
 
+                /* special case - (INCLUDE, empty) == LEAVE_GROUP */
+                if (psl->sl_count == 1 && omode == MCAST_INCLUDE) {
+                        leavegroup = 1;
+                        goto done;
+                }
+
                 /* update the interface filter */
                 ip_mc_del_src(in_dev, &mreqs->imr_multiaddr, omode, 1, 
                         &mreqs->imr_sourceaddr, 1);
@@ -1831,6 +1838,8 @@ int ip_mc_source(int add, int omode, struct sock *sk, struct
                 &mreqs->imr_sourceaddr, 1);
 done:
         rtnl_shunlock();
+        if (leavegroup)
+                return ip_mc_leave_group(sk, &imr);
         return err;
 }