BIND 10 #1512: implement zone section processing in DDNS

[BIND 10 Development]

#1512: implement zone section processing in DDNS
-------------------------------------+-------------------------------------
                   Reporter:  jelte  |                 Owner:  jinmei
                       Type:  task   |                Status:  accepted
                   Priority:         |             Milestone:
  medium                             |  Sprint-20120529
                  Component:  DDNS   |            Resolution:
                   Keywords:         |             Sensitive:  0
            Defect Severity:  N/A    |           Sub-Project:  DNS
Feature Depending on Ticket:  DDNS   |  Estimated Difficulty:  6
        Add Hours to Ticket:  0      |           Total Hours:  0
                  Internal?:  0      |
-------------------------------------+-------------------------------------

Comment (by jinmei):

 trac1512 is ready for review.

 First off, I chose to introduce a supplemental library package
 isc.ddns, and define the update session class in a separate module
 of the package.  This is because I'd expect there might be some other
 such supplemental modules (e.g., if and when we support more
 sophisticated update ACL), and by using the package we can have
 multiple submodules naturally.  I also wanted to make the main
 protocol handling logic as less b10-ddns specific as possible (for
 example, that the request comes from auth via a socket session
 channel) so that this part won't be affected by any architecture
 change in b10-ddns and can even be used by other (possibly
 third-party) modules.

 Secondly, I needed to introduce a couple of extensions to libdns++ and
 its python wrapper for necessary functionality.  They are commits
 f3e8996 and 80c031b.  The latter is actually a subject of another
 ticket (#1883), and I could have completed this task without it,
 but, as commented in the commit log, I thought it would be needed
 widely (xfrin/xfrout would benefit from it) and would help keep the
 application side simpler/less-buggy.  The changes are not big, and I
 hope they can be accepted as part of this task.

 Third, there's no link between the b10-ddns yet.  The branch is
 getting bigger due to the generic framework and libdns++ updates, so I
 think it's better to move that part to some of the other DDNS tasks.
 I guess #1458 is relatively easy and it's a good place to complete it.
 If this approach is okay I'll update the #1458 description
 accordingly; or I can extend this branch if that's more reasonable.

 The main code for the subject of this task itself (the
 `UpdateSession.handle` method) is pretty small and should be
 straightforward.  The branch is big mainly due to the various setups
 and supplemental extensions.

-- 
Ticket URL: <http://bind10.isc.org/ticket/1512#comment:8>
BIND 10 Development <http://bind10.isc.org>
BIND 10 Development