ankohuu commented on code in PR #18738:
URL: https://github.com/apache/nuttx/pull/18738#discussion_r3086373480
##########
net/ipforward/ipv4_forward.c:
##########
@@ -634,6 +634,18 @@ void ipv4_forward_broadcast(FAR struct net_driver_s *dev,
return;
}
+ /* Do not forward link-local multicast packets (224.0.0.0/24).
+ * Per RFC 3171, addresses in 224.0.0.0/24 are reserved for
+ * link-local scope and MUST NOT be forwarded by any router,
+ * regardless of TTL.
+ */
+
+ if ((net_ip4addr_conv32(ipv4->destipaddr) &
+ HTONL(0xffffff00)) == HTONL(0xe0000000))
+ {
+ return;
Review Comment:
I don’t think this needs to be added:
- During IGMP initialization, 224.0.0.1 is joined, which looks reasonable.
[https://github.com/apache/nuttx/blob/12e8f92a282fac58e0dfff587ea3d9502e4804c0/net/igmp/igmp_initialize.c#L86](url)
- For multicast forwarding, the current logic appears to depend on the
groups joined by the local host; I’m not trying to change this behavior.
- So hitting this case is expected
Let's don’t report it, just drop it.
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