port-amd64/50705: DHCP client daemon broken in NetBSD 7.0 INSTALL image

[dean%av8.net@localhost]

>Number:         50705
>Category:       port-amd64
>Synopsis:       DHCP client daemon broken in NetBSD 7.0 INSTALL image
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    port-amd64-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Jan 25 01:05:00 +0000 2016
>Originator:     Dean Anderson
>Release:        7.0
>Organization:
AV8 Internet
>Environment:
NetBSD 7.0 (INSTALL_XEN3_DOMU.201509250726Z)
>Description:
There is a bug in the dhcp client software setup on the 7.0 INSTALL image for
amd64:

The impact is that Cisco IOS ip helper won't forward the packet:

av8-nj1-gw2#debug ip dhcp server packet
DHCP server packet debugging is on.
av8-nj1-gw2#term mon
av8-nj1-gw2#
Jan 25 00:18:39.385: DHCPD: option 12 is malformed (option length 0).
Jan 25 00:18:39.385: DHCPD: invalid DHCP options - unable to parse


19:18:39.956564 00:16:3e:04:00:09 (oui Unknown) > Broadcast, ethertype
IPv4 (0x0800), length 375: (tos 0x0, ttl 64, id 20794, offset 0, flags [none], proto UDP (17), length 361) 0.0.0.0.bootpc > 255.255.255.255.bootps: [udp sum ok] BOOTP/DHCP, Request from 00:16:3e:04:00:09$
Flags [none] (0x0000)
          Client-Ethernet-Address 00:16:3e:04:00:09 (oui Unknown)
          Vendor-rfc1048 Extensions
            Magic Cookie 0x63825363
            DHCP-Message Option 53, length 1: Discover
            Client-ID Option 61, length 19: hardware-type 255, 3e:04:00:09:00:01:00:01:1e:38:22:57:00:16:3e:04:00:09
            SLP-NA Option 80, length 0""  
            NOAUTO Option 116, length 1: Y
            MSZ Option 57, length 2: 1500
            Vendor-Class Option 60, length 36: "dhcpcd-6.7.1:NetBSD-7.0:amd64:x86_64"
            Hostname Option 12, length 0""
            T145 Option 145, length 1: 1
            Parameter-Request Option 55, length 14:
              Subnet-Mask, Option 121, Static-Route, Default-Gateway
              Domain-Name-Server, Hostname, Domain-Name, BR
              NTP, Lease-Time, Server-ID, RN
              RB, Option 119
            END Option 255, length 0


Option 12 probably shouldn't be set when the hostname is not set, and isn't set in NetBSD 6.1.5 INSTALL image.
In any case, it can't be length 0:

RFC2132 states:

3.14. Host Name Option
   
   This option specifies the name of the client.  The name may or may   
   not be qualified with the local domain name (see section 3.17 for the
   preferred way to retrieve the domain name).  See RFC 1035 for
   character set restrictions.

>How-To-Repeat:
Configure network 1 with dhcp server
Configure network 2 with ip helper on Cisco


Boot the distributed netbsd 7.0 amd64 INSTALL image, attempt to use NFS to install,  and when it prompts, configure network 'auto' via DHCP on network 2


>Fix:
You have two choices:

1) either set a hostname before configuring the network with DHCP

2) remove the hostname config line from the /etc/dhcpcd.conf file


You could optionally suggest to the ISC folks that the dhcpcd should check that when given the hostname option in the config file and the hostname is not actually set, that it should ignore it, rather then sending an invalid option.