[pkg-dhcp-devel] Bug#617258: isc-dhcp-relay: segfaults if client-facing interface has label

[Marc Haber]

Hi Andrew,

sorry for taking so long to reply.

The bug has changed. dhcrelay does not crash any more, but it does
also not work.

root at testkiste:/home/mh# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST> mtu 1500 qdisc pfifo_fast state DOWN qlen 1000
    link/ether 52:54:00:24:af:60 brd ff:ff:ff:ff:ff:ff
root at testkiste:/home/mh# ip link set dev eth0 up
root at testkiste:/home/mh# ip addr add dev eth0 192.168.18.23/24 brd + label eth0:foo
root at testkiste:/home/mh# ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 52:54:00:24:af:60 brd ff:ff:ff:ff:ff:ff
    inet 192.168.18.23/24 brd 192.168.18.255 scope global eth0:foo
    inet6 fe80::5054:ff:fe24:af60/64 scope link
       valid_lft forever preferred_lft forever
root at testkiste:/home/mh# dhcrelay -d -i eth0 -i eth0 192.168.18.100             Internet Systems Consortium DHCP Relay Agent 4.2.2
Copyright 2004-2011 Internet Systems Consortium.
All rights reserved.
For info, please visit https://www.isc.org/software/dhcp/
Listening on LPF/eth0/52:54:00:24:af:60
Sending on   LPF/eth0/52:54:00:24:af:60
Listening on LPF/eth0/52:54:00:24:af:60
Sending on   LPF/eth0/52:54:00:24:af:60
Sending on   Socket/fallback
Discarding packet received on eth0 interface that has no IPv4 address assigned.
Discarding packet received on eth0 interface that has no IPv4 address assigned. 

It is perfectly OK to have the only IP address on an Interface
labeled. dhcrelay does seem to explicitly check for that and to bail
if no unlabeled IP address is found. I think that behavior is wrong,
dhcrelay should just use a labeled IP address as if it were unlabeled.

The eth0:foo interface is working perfectly fine IP-wise; I actually
sshed in to the VM through that interface to be able to cut&paste the
typescript to this mail.

Please note that this is eth0:foo, not eth0.foo. The period notation
is not a label, it is an alias. I think _this_ works, the misbehavior
happens when a label (colon notation) is used.

Greetings
Marc

-- 
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Marc Haber         | "I don't trust Computers. They | Mailadresse im Header
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