Re: Ethereal comparison 1.265 vs 1.270 DHCP Discover

[Bill Moss <bmoss clemson edu>]

Your patch did not work. From experience with dhcpcd.c, I knew it would 
not work but I also knew how to fix it. The 1.265 and 1.270-mypatch 
discovery messages that work are 346 bytes and the UDP part is 312. The 
1.270 discovery message that does not work is 331 bytes and the UDP part 
is 297. I believe this may be a size issue. The SMC AP/DHCP server seems 
to be rejecting the discovery message because its size is too small. 
Your patch will not work with

DHCP_CLASS_ID_MAX_LEN, "%s", sname.sysname);

OR

DHCP_CLASS_ID_MAX_LEN, "%s %s", sname.sysname, sname.release);

It only works with

DHCP_CLASS_ID_MAX_LEN, "%s %s %s", sname.sysname, sname.release, 
sname.machine);

If I am right about size and this is an issue for older hardware, then 
saving a few bytes in the dhcp discovery message is not worth it.

Dan Williams wrote:

> On Fri, 2005-02-11 at 16:02 -0500, Bill Moss wrote:
>  
>
> > Bootstrap Protocol identical down to
> >
> > 1.270:
> > Option 53 DHCP Message TYPE = DHCP Discover
> > Option 57: Maximum DHCP Message Size = 548
> > Option 51: IP Address Lease Time = infinity
> > Option 55: Parameter Request List
> > Option 12: Host Name = "localhost.localdomain"
> > == SMC DHCP does not send an ARP. It is stuck here. It doesn't like 
> > something about the way this message is constructed. All checksums 
> > are correct in all parts of the message.
> >
> > 1.265
> > Option 53 DHCP Message TYPE = DHCP Discover
> > Option 57: Maximum DHCP Message Size = 548
> > Option 51: IP Address Lease Time = infinity
> > Option 55: Parameter Request List
> > Option 60: Vendor class identifier = "Linux 2.6.10-1.760_FC3 i686"
> > Option 61: Client identifier
> > == SMC DHCP immcdiately sends an ARP and the process continues to 
> > completion
> >   
>
>
> Bill,
>
> Could you apply this patch, rebuild, and try again?  It should revert
> the DHCP message options to what they were before, ie making it send the
> Client & Class ID but not the hostname.
>
> Dan
>  

--
Bill Moss
Professor, Mathematical Sciences
Clemson University

--
Bill Moss
Professor, Mathematical Sciences
Clemson University