make sure that if a subnet has no gateway the router option is not sent in the dhcp offer.

[Nachi Ueno]

A slightly more detailed analysis (meaning I've actually looked at the code, and its history) suggests we go for two bugs.

This bugs might address the dhcp issue, as:

    def _output_opts_file(self):
        """Write a dnsmasq compatible options file."""
        # TODO (mark): add support for nameservers
        options = []
        for i, subnet in enumerate(self.network.subnets):
            if subnet.ip_version == 6:
                continue
            else:
                options.append((self._TAG_PREFIX % i,
                                'option',
                                'router',
                                subnet.gateway_ip))

        name = self.get_conf_file_name('opts')
        replace_file(name, '\n'.join(['tag:%s,%s:%s,%s' % o for o in options]))
        return name

Will always assign the dhcp router option no matter what is in the gateway_ip attribute.
For the API layer, we need a solution for specifying subnets without a default gateway. Nachi, could you please file another bug report for it?

Drived from https://bugs.launchpad.net/quantum/+bug/1025817

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/12085

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/12085
Committed: http://github.com/openstack/quantum/commit/4b5a850a51ee1a8451a9c5e819fb5247bf4d46d0
Submitter: Jenkins
Branch: master

commit 4b5a850a51ee1a8451a9c5e819fb5247bf4d46d0
Author: Nachi Ueno <email address hidden>
Date: Wed Aug 29 00:02:49 2012 +0000

    Fix dhcp option distribution by dnsmasq

    Fixes bug 1022737 host route per subnet distribution
    Fixes bug 1028647 --no-gateway support on dhcp agent
    Fixes bug 1043022 dns distribution

    Change-Id: I567f1f8d1f5d386a253be1965d29f2533f7e88c8