[U-Boot-Users] [PATCH] DHCP Client Fix

[Justin Flammia]

Ben,

Just a note...one of the ways that I came up with this solution that is presented in this patch was from observing a Fedora Linux machine and an Apple MacBook Pro interact with the same routers because these computers were able to get an IP address through either Linksys DHCP server consistently.  There were some differences in the data that was included in each of the DHCP negotiation packets but it was the difference you see in the patch that allowed U-Boot to work with the new firmware. After doing some research on DHCP IP assignments, this seemed like a viable solution according to the spec.

Justin


>Wolfgang Denk wrote:
>>Dear Justin,
>>
>>in message <4155D0DA4B6B044891B3F19311C7E7B89C45E4 at EXCHANGE1.886llc.local> you wrote:
>>  
>>>I recently upgraded the firmware on some of my old Linksys WRT54G
>>>routers (version 5) from firmware version 1.0.6 to firmware version
>>>1.02.2, both of which are released by Linksys and U-Boot was no longer
>>>able to get an IP address using DHCP.  However, with the older firmware
>>>(version 1.0.6), U-Boot was still able to get an IP through DHCP.
>>>
>>>Using a hub and a packet sniffer, I was able to locate the problem.  The
>>>U-Boot code will bind to an IP address offered by the DHCP server
>>>prematurely and the DHCP server will not respond with an ACK, rendering
>>>    
>>
>>I have to admit that I'm not sure if this is a bug in  U-Boot  or  in
>>the  Linksys  router  (which I have under special observation as they
>>explicitely and intentionally violate the U-Boot GPL).
>>
>>
>>>the system without an IP address.  This is no longer valid when using a
>>>Linksys router as DHCP server.  I modified the code to operate the way
>>>the Linux DHCP client does by not binding to the offered IP until the
>>>DHCP client receives the ACK sent by the server, ending the
>>>conversation.  After making the appropriate changes, DCHP service was
>>>restored for all flavors of the Linksys firmware that I have available
>>>(v 1.02.2 and v1.0.6 for the version 5 router, v8.00.2 for the version 8
>>>router).  It has also been tested on an AirPort Extreme router running
>>>DHCP.
>>>
>>>Attached is the patch with the code changes that were made. Any feed
>>>back would be appreciated.
>>>    
>>>
>>
>>I'm waiting for feedback (or a pull request?) from the network
>>custodian.
>>
>>Ben???
>>
>>
>This looks promising.  I'll provide feedback after doing some testing tomorrow.
>
>regards,
>Ben  
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