From bceab38aa68be075841d573f63a9a9c432bf1fda Mon Sep 17 00:00:00 2001
From: Tom Henderson <tomh@tomh.org>
Date: Tue, 19 Sep 2023 17:05:05 -0700
Subject: [PATCH] internet: (fixes #956) Avoid sending RS when link goes down

---
 src/internet/model/icmpv6-l4-protocol.cc | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/internet/model/icmpv6-l4-protocol.cc b/src/internet/model/icmpv6-l4-protocol.cc
index 3bd99ecd8..878da2695 100644
--- a/src/internet/model/icmpv6-l4-protocol.cc
+++ b/src/internet/model/icmpv6-l4-protocol.cc
@@ -1350,6 +1350,17 @@ Icmpv6L4Protocol::SendRS(Ipv6Address src, Ipv6Address dst, Address hardwareAddre
         p->AddHeader(llOption);
     }
 
+    if (!src.IsAny())
+    {
+        Ptr<Ipv6L3Protocol> ipv6 = m_node->GetObject<Ipv6L3Protocol>();
+        if (ipv6->GetInterfaceForAddress(src) == -1)
+        {
+            NS_LOG_INFO("Preventing RS from being sent or rescheduled because the source address "
+                        << src << " has been removed");
+            return;
+        }
+    }
+
     NS_LOG_LOGIC("Send RS (from " << src << " to " << dst << ")");
 
     rs.CalculatePseudoHeaderChecksum(src, dst, p->GetSize() + rs.GetSerializedSize(), PROT_NUMBER);