Re: [lwip-users] RFC: ARP Queueing

[Leon Woestenberg]

Hello Paul,

Paul wrote:
> I think that ARP_QUEUEING needs to be patched in netif/etharp.c
> Here is what I think is needed.
>
>      /* i is available, create ARP entry */
>      arp_table[i].state = ETHARP_STATE_PENDING;
>      ip_addr_set(&arp_table[i].ipaddr, ipaddr);
>    /* queried address was already in ARP table */
> -  } else {
> +  }
>  #if ARP_QUEUEING
>      etharp_enqueue(i, q);
>  #endif
>
Yes, you found a bug there. Thanks for reporting it.

Your patch fixes it, but only for the case where the ARP entry was just 
created (with STATE_PENDING).

In case the entry was already stable, we should immediately send out the
packet-submitted-for-queue on the network link OR ALTERNATIVELY queue
the packet and initiate a query for the address (so that it is triggered
for transmission upon reception of the ARP response).

I chose to implement the latter method (so to actively freshen the ARP 
cache when asked to query the address).

I have applied your patch, and my fix for the other case to the main
branch.

Please test and report and I will then apply it to the STABLE 0.7.x
release branch for an upcoming stable release.

Thanks,

Leon Woestenberg.