[lwip-users] 1.2.0 etharp_ip_input change

[Jonathan Larmour]

I was wondering about the following change in 1.2.0. Isn't updating the ARP 
table from incoming IP packets a good thing and normal practice? Otherwise 
for something which isn't already in the ARP cache (especially a new TCP 
connection, or UDP from a novel host) won't the lwip stack need to send an 
ARP request for any response?

Note I haven't tried 1.2.0 yet - I wanted to review changes before jumping. 
I couldn't find any discussion about this change in lwip-users/devel around 
2006-05-05 (when it was made) so there may well be prior discussed 
motivation I just haven't seen.

Jifl

Index: src/netif/ethernetif.c
===================================================================
RCS file: /sources/lwip/lwip/src/netif/ethernetif.c,v
retrieving revision 1.22
retrieving revision 1.24
diff -u -5 -p -r1.22 -r1.24
--- src/netif/ethernetif.c      17 Oct 2004 18:13:18 -0000      1.22
+++ src/netif/ethernetif.c      14 Jul 2006 11:17:00 -0000      1.24
@@ -237,12 +237,16 @@ ethernetif_input(struct netif *netif)
   ethhdr = p->payload;

   switch (htons(ethhdr->type)) {
   /* IP packet? */
   case ETHTYPE_IP:
+#if 0
+/* CSi disabled ARP table update on ingress IP packets.
+   This seems to work but needs thorough testing. */
     /* update ARP table */
     etharp_ip_input(netif, p);
+#endif
     /* skip Ethernet header */
     pbuf_header(p, -sizeof(struct eth_hdr));
     /* pass to network layer */
     netif->input(p, netif);
     break;


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