[U-Boot-Users] Duplicate IP address check

[gvb.uboot <gvb.uboot@gmail.com>]

Ben Warren wrote:
> gvb.uboot wrote:
>> Ben Warren wrote:
>>> Hi Dan,
>>>
>>> Dan Batryn wrote:
>>>> Due to a mis-configuration of our DHCP server there was an
>>>> overlapping range of DHCP assigned IP address and units configured
>>>> to have IP addresses statically assigned. I was surprised to find
>>>> that UBOOT did not complain of a duplicate IP address while trying
>>>> to boot via the network. Looking through the source I cannot see
>>>> any code to perform the typical ARP for yourself check that I have
>>>> seen before. Could someone please tell me if I have overlooked
>>>> something or is this feature missing?
>>>>
>>> There is no explicit check for duplicate IP assignment. U-boot's 
>>> networking code is intentionally minimalist and thus lacks many such 
>>> features. Feel free to provide a patch and a convincing argument of 
>>> why it's needed.
>>>
>>> regards,
>>> Ben
>>
>> Ditto on the patch.
>>
>> WRT the convincing argument, I think the bar would be *really* low on 
>> this one. :-) I would consider a convincing argument to be "The nearly 
>> universal convention of performing an ARP to verify that the 
>> DHCP-assigned IP address is unused is missing."
> Sure, this is a no-brainer. But, it shouldn't be limited to DHCP since 
> having a dynamic address trouncing a static one is only one trouble 
> scenario. Who knows, there may be people out there who object to the 
> extra milliseconds that this ARP will add to boot time (not me).
> 
> regards,
> Ben

Ahh, so right.  It is actually a worse risk for human-assigned 
addresses.  s/DHCP-//

It would be simple enough to have a configurable ARP response wait 
timeout and use a special value (say <= 0) to disable the ARP test.

gvb