MFC r291579:

  In the same way fix the problem described in r291578 for IGMPv3.

  In case when router has a lot of multicast groups, the reply can take
  several packets due to MTU limitation.
  Also we have a limit IGMP_MAX_RESPONSE_BURST == 4, that limits the number
  of packets we send in one shot. Then we recalculate the timer value and
  schedule the remaining packets for sending.
  The problem is that when we call igmp_v3_dispatch_general_query() to send
  remaining packets, we queue new reply in the same mbuf queue. And when
  number of packets is bigger than IGMP_MAX_RESPONSE_BURST, we get endless
  reply of IGMPv3 reports.
  To fix this, add the check for remaining packets in the queue.

1 files changed, 10 insertions, 0 deletions

diff --git a/sys/netinet/igmp.c b/sys/netinet/igmp.c
index c138f14..34a60a8 100644
--- a/sys/netinet/igmp.c
+++ b/sys/netinet/igmp.c
@@ -3327,6 +3327,15 @@ igmp_v3_dispatch_general_query(struct igmp_ifinfo *igi)
 	KASSERT(igi->igi_version == IGMP_VERSION_3,
 	    ("%s: called when version %d", __func__, igi->igi_version));
 
+	/*
+	 * Check that there are some packets queued. If so, send them first.
+	 * For large number of groups the reply to general query can take
+	 * many packets, we should finish sending them before starting of
+	 * queuing the new reply.
+	 */
+	if (igi->igi_gq.ifq_head != NULL)
+		goto send;
+
 	ifp = igi->igi_ifp;
 
 	IF_ADDR_RLOCK(ifp);
@@ -3362,6 +3371,7 @@ igmp_v3_dispatch_general_query(struct igmp_ifinfo *igi)
 	}
 	IF_ADDR_RUNLOCK(ifp);
 
+send:
 	loop = (igi->igi_flags & IGIF_LOOPBACK) ? 1 : 0;
 	igmp_dispatch_queue(&igi->igi_gq, IGMP_MAX_RESPONSE_BURST, loop);