VPNaaS needs MTU checked when creating/updating connection

[Paul Michali]

Add validation in plugin for MTU during ipsec site connection creation and updating. For now, use subnet from vpnservice object to tell whether protocol is IPv4 or IPv6 and check MTU against minimum of 68 and 1280, respectively.

This cannot be done by extension or client side, as it depends on multiple objects.

In future, when add support for multiple protocols on a connection, will take the minimum of each.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/44933

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/44933
Committed: http://github.com/openstack/neutron/commit/0f9411948221b1df70d4a3f3d1271f821bea74aa
Submitter: Jenkins
Branch: master

commit 0f9411948221b1df70d4a3f3d1271f821bea74aa
Author: Paul Michali <email address hidden>
Date: Mon Sep 2 07:02:12 2013 -0400

    Verify MTU is valid for ipsec_site_connection

    Since the check relies on the vpnservice subnet to determine whether
    this is IPv4 ro IPv6, we must check in the plugin. Test is done at
    create/update time and ensures that the MTU is equal to or greater
    than the minimum allowed values, which are set to 68 for IPv4
    minimum and 1280 for IPv6, respectively.

    Refactored code to allow reuse of create and update test functions,
    by allowing tests to override some settings, and to provide a dict
    of changed items (for update).

    bug 1219489

    Change-Id: I3e62ef786d3a02c761903a15d546ee8758c0bf7f