problem with 3.1.1 not returning router address

[Jeff Wieland]

We're seeing a problem with ISC DHCP 3.1.1 where it sometimes does
not return the router IP to the client, even though the client asks
for it in the PRL.  Instead, it returns the subnet-mask twice.  With
the same config file, 3.1.0 does not do this.

I suspect that this relates to this change that was made:

- The subnet-mask option inclusion now conforms with RFC2132 section 3.3;
   it will only appear prior to the routers option if it is present on the
   Parameter-Request-List.  The subnet-mask option will also only be
   included by default (if it is not on the PRL) in response to DISCOVER
   or REQUEST messages.


For instance, the client asks for (this is from snoop on Solaris 10):

DHCP: Requested Options:
DHCP:    3 (Router)
DHCP:    1 (Subnet Mask)
DHCP:    6 (DNS Servers)
DHCP:   15 (DNS Domain Name)

and DHCP 3.1.1 responds with (IPs and names changed to protect the
innocent):

DHCP: Message type = DHCPACK
DHCP: DHCP Server Identifier = 192.168.0.3
DHCP: IP Address Lease Time = 60 seconds
DHCP: Subnet Mask = 255.255.255.0
DHCP: Subnet Mask = 255.255.255.0
DHCP: DNS Servers at = 192.168.0.3
DHCP: DNS Servers at = 192.168.0.4
DHCP: DNS Domain Name = foobar.purdue.edu
DHCP: Server Name = not.foobar.purdue.edu


In every instance of this problem with 3.1.1 that we've seen so far,
the client has asked for the router before the subnet mask.
-- 
           Jeff Wieland            |         Purdue University
    Network Systems Administrator  |        ITN&S Data Networks
        Voice: (765)496-8234       |        501 Harrison Street
         FAX: (765)494-6620        |   West Lafayette, IN 47907-2025