DHCP agent should specify prefix-len for IPv6 dhcp-range's

[Alexey I. Froloff]

If Network contains Subnet smaller than /64, prefix-len should be specified for dnsmasq's --dhcp-range option.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/125026

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/125026
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=f996a7b46878f543ecf775380529af10fe87b8cb
Submitter: Jenkins
Branch: master

commit f996a7b46878f543ecf775380529af10fe87b8cb
Author: Alexey I. Froloff <email address hidden>
Date: Tue Sep 30 16:37:19 2014 +0400

    Specify prefix length for IPv6 subnets

    If Network contains dhcpv6-stateful Subnet with prefix other than /64,
    dnsmasq refuses to start if prefix-len is not specified in dhcp-range
    option. From dnsmasq(8) manpage:

        For IPv6, the parameters are slightly different: instead of netmask
        and broadcast address, there is an optional prefix length which must
        be equal to or larger then the prefix length on the local interface.
        If not given, this defaults to 64. Unlike the IPv4 case, the prefix
        length is not automatically derived from the interface
        configuration. The mimimum size of the prefix length is 64.

    It is safe to always specify prefix length, so dnsmasq will use correct
    configuration.

    Change-Id: Ibef1f55926585016f0054accd7f7ef5a022e3fe1
    Closes-Bug: #1372883

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/juno
Review: https://review.openstack.org/147799

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/147799
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=82bf4afdf9a80a3f7875d1908c5fac17fd037fee
Submitter: Jenkins
Branch: stable/juno

commit 82bf4afdf9a80a3f7875d1908c5fac17fd037fee
Author: Alexey I. Froloff <email address hidden>
Date: Tue Sep 30 16:37:19 2014 +0400

    Specify prefix length for IPv6 subnets

    If Network contains dhcpv6-stateful Subnet with prefix other than /64,
    dnsmasq refuses to start if prefix-len is not specified in dhcp-range
    option. From dnsmasq(8) manpage:

        For IPv6, the parameters are slightly different: instead of netmask
        and broadcast address, there is an optional prefix length which must
        be equal to or larger then the prefix length on the local interface.
        If not given, this defaults to 64. Unlike the IPv4 case, the prefix
        length is not automatically derived from the interface
        configuration. The mimimum size of the prefix length is 64.

    It is safe to always specify prefix length, so dnsmasq will use correct
    configuration.

    Change-Id: Ibef1f55926585016f0054accd7f7ef5a022e3fe1
    Closes-Bug: #1372883
    (cherry picked from commit f996a7b46878f543ecf775380529af10fe87b8cb)

[Eran Kuris (ekuris)]

According to this https://github.com/openstack/neutron/blob/master/neutron/db/db_base_plugin_v2.py#L737
how can I verify this bug ?

[Alexey I. Froloff (raorn)]

https://github.com/openstack/neutron/blob/master/neutron/common/ipv6_utils.py#L67

Make it return False.

[Eran Kuris (ekuris)]

Alexey , how can I make it return false , dont really understand ?!?!

[Alexey I. Froloff (raorn)]

This method returns False for DHCPv6-stateful subnets. If this method returns False, prefixlen is not checked for this subnet.

[Eran Kuris (ekuris)]

so this bug is relevant only for DHCPv6-stateful ??

[Alexey I. Froloff (raorn)]

Eran, have you tried reading the commit message?

[Eran Kuris (ekuris)]

off course I'm but I don't understand you.
I saw " modes = [constants.IPV6_SLAAC, constants.DHCPV6_STATELESS]"
but I don't understand how this method returns false for stateful subnets .
I tried to create stateless subnet less then /64 but I got an error . I trying to understand how can i reproduce this bug .

[Alexey I. Froloff (raorn)]

Why are you creating stateless subnet, whilecommit message mentions stateful subnet?

[Eran Kuris (ekuris)]

def is_auto_address_subnet(subnet):
    """Check if subnet is an auto address subnet."""
    modes = [constants.IPV6_SLAAC, constants.DHCPV6_STATELESS]
    return (subnet['ipv6_address_mode'] in modes
            or subnet['ipv6_ra_mode'] in modes)

According to this I don't see stateful .

[Eran Kuris (ekuris)]

Alexey , I want to reproduce the problem . please write me steps what should I do to reproduce it .
step by step and it will help me to understand the problem.
thanks

[Eran Kuris (ekuris)]

Alexly , finally I success to create stateful subnet smaller then /64
I want to understand what I expected to see in dnsmasq???

[root@puma15 ~(keystone_admin)]# neutron subnet-show 76c13e30-31e3-4706-97b1-ea23dc7055f1
+-------------------+----------------------------------------------------------+
| Field | Value |
+-------------------+----------------------------------------------------------+
| allocation_pools | {"start": "2001::2", "end": "2001::ffff:ffff:ffff:fffe"} |
| cidr | 2001::/64 |
| dns_nameservers | |
| enable_dhcp | True |
| gateway_ip | 2001::1 |
| host_routes | |
| id | 76c13e30-31e3-4706-97b1-ea23dc7055f1 |
| ip_version | 6 |
| ipv6_address_mode | dhcpv6-stateful |
| ipv6_ra_mode | dhcpv6-stateful |
| name | ipv6_stateful |
| network_id | e6ced721-0539-48b9-9b1b-35d89a26c23f |
| tenant_id | e706e4f6180447f9b6acba60086948ab |
+-------------------+----------------------------------------------------------+
# ps -ef | grep dnsmasq
nobody 14607 1 0 Mar15 ? 00:00:00 dnsmasq --no-hosts --no-resolv --strict-order --bind-interfaces --interface=tapeb7835e5-fb --except-interface=lo --pid-file=/var/lib/neutron/dhcp/afddd5d9-9178-467b-8d2f-9953f4be998a/pid --dhcp-hostsfile=/var/lib/neutron/dhcp/afddd5d9-9178-467b-8d2f-9953f4be998a/host --addn-hosts=/var/lib/neutron/dhcp/afddd5d9-9178-467b-8d2f-9953f4be998a/addn_hosts --dhcp-optsfile=/var/lib/neutron/dhcp/afddd5d9-9178-467b-8d2f-9953f4be998a/opts --leasefile-ro --dhcp-range=set:tag0,192.168.1.0,static,86400s --dhcp-lease-max=256 --conf-file=/etc/neutron/dnsmasq-neutron.conf --domain=openstacklocal
root 28775 28689 0 11:50 pts/2 00:00:00 grep --color=auto dnsmasq

[Alexey I. Froloff (raorn)]

No, you don't. And this dnasmasq is serving different network.

[Eran Kuris (ekuris)]

how can we contact via IRC ?