From 16605f2fdad730b8bb570e17192dc5f45cf15d3f Mon Sep 17 00:00:00 2001
From: "Ondrej Zajicek (work)" <santiago@crfreenet.org>
Date: Sun, 3 Feb 2019 17:31:27 +0100
Subject: [PATCH] OSPF: Reject duplicate DBDES packets after dead interval

Master may free last DBDES packet immediately. Slave must wait dead
interval before freeing last DBDES packet and then reject duplicate
DBDES packets with SeqNumberMismatch.
---
 proto/ospf/dbdes.c    | 13 +++++++++++++
 proto/ospf/neighbor.c |  6 ++++++
 proto/ospf/ospf.h     |  1 +
 3 files changed, 20 insertions(+)

diff --git a/proto/ospf/dbdes.c b/proto/ospf/dbdes.c
index 4d3bbe8c..a1559782 100644
--- a/proto/ospf/dbdes.c
+++ b/proto/ospf/dbdes.c
@@ -238,6 +238,14 @@ ospf_rxmt_dbdes(struct ospf_proto *p, struct ospf_neighbor *n)
   ospf_do_send_dbdes(p, n);
 }
 
+void
+ospf_reset_ldd(struct ospf_proto *p UNUSED, struct ospf_neighbor *n)
+{
+  mb_free(n->ldd_buffer);
+  n->ldd_buffer = NULL;
+  n->ldd_bsize = 0;
+}
+
 static int
 ospf_process_dbdes(struct ospf_proto *p, struct ospf_packet *pkt, struct ospf_neighbor *n)
 {
@@ -434,6 +442,7 @@ ospf_receive_dbdes(struct ospf_packet *pkt, struct ospf_iface *ifa,
       if (!(n->myimms & DBDES_M) && !(n->imms & DBDES_M))
       {
 	tm_stop(n->dbdes_timer);
+	ospf_reset_ldd(p, n);
 	ospf_neigh_sm(n, INM_EXDONE);
 	break;
       }
@@ -457,7 +466,11 @@ ospf_receive_dbdes(struct ospf_packet *pkt, struct ospf_iface *ifa,
       ospf_send_dbdes(p, n);
 
       if (!(n->myimms & DBDES_M) && !(n->imms & DBDES_M))
+      {
+	/* Use dbdes timer to postpone freeing of Last DBDES packet buffer */
+	tm_start(n->dbdes_timer, n->ifa->deadint S);
 	ospf_neigh_sm(n, INM_EXDONE);
+      }
     }
     break;
 
diff --git a/proto/ospf/neighbor.c b/proto/ospf/neighbor.c
index 54d643c6..c143b130 100644
--- a/proto/ospf/neighbor.c
+++ b/proto/ospf/neighbor.c
@@ -608,6 +608,12 @@ dbdes_timer_hook(timer *t)
 
   if ((n->state == NEIGHBOR_EXCHANGE) && (n->myimms & DBDES_MS))
     ospf_rxmt_dbdes(p, n);
+
+  if ((n->state > NEIGHBOR_LOADING) && !(n->myimms & DBDES_MS))
+  {
+    ospf_reset_ldd(p, n);
+    tm_stop(n->dbdes_timer);
+  }
 }
 
 static void
diff --git a/proto/ospf/ospf.h b/proto/ospf/ospf.h
index 23289ccd..d3f12738 100644
--- a/proto/ospf/ospf.h
+++ b/proto/ospf/ospf.h
@@ -1041,6 +1041,7 @@ uint ospf_hello3_options(struct ospf_packet *pkt);
 /* dbdes.c */
 void ospf_send_dbdes(struct ospf_proto *p, struct ospf_neighbor *n);
 void ospf_rxmt_dbdes(struct ospf_proto *p, struct ospf_neighbor *n);
+void ospf_reset_ldd(struct ospf_proto *p, struct ospf_neighbor *n);
 void ospf_receive_dbdes(struct ospf_packet *pkt, struct ospf_iface *ifa, struct ospf_neighbor *n);
 uint ospf_dbdes3_options(struct ospf_packet *pkt);