Truncated packet (280) error message from dhcpcd

[Paul Goyette <paul%whooppee.com@localhost>]

Recently I'm seeing the 're0: truncated packet (280) from' error 
message.  Nothing has changed from the ISP provider, and I'm still using 
the same DSL modem/router/NAT device that I've been using for the last 
two years.

It appears that the code checking the packet length was substantively 
modified a few weeks ago.  Prior to these changes in dhcp.c, rev 1.43 I 
may have been receiving these truncated packets, but they were still 
being processed, and dhcpcd was able to ignore the truncation and 
successfully negotiated a lease.  But with -current code these packets 
are ignored, and no lease ever occurs, so the host doesn't "come up" on 
the network.

While it is entirely likely that my ISP's device is ultimately at fault 
here (since it is apparently violating the packet formatting specified 
in the RFC), the missing/truncated information is most likely not 
critical to proper operation (since it used to work just fine before the 
length checks were changed).  Using the principal of "be conservative in 
what you send, and liberal in processing what you receive" it would seem 
to me that a more proper response here would be to log the truncated 
packets but still process them.  The packet(s) should be dropped only if 
there is critical content missing, and which cannot be "defaulted" or 
otherwise "assumed".

Would it be possible to be less strict in checking the packet lengths? 
Please?

:)


PS Of course I can always assign a static address in the 192.168.1.x 
range, and everything works if I do this.  But I shouldn't have to do 
this, and until these recent changes, I didn't need to.  :)

Thanks in advance!



+------------------+--------------------------+------------------------+
| Paul Goyette     | PGP Key fingerprint:     | E-mail addresses:      |
| (Retired)        | FA29 0E3B 35AF E8AE 6651 | paul at whooppee.com   |
| Kernel Developer | 0786 F758 55DE 53BA 7731 | pgoyette at netbsd.org |
+------------------+--------------------------+------------------------+