BIND 10 #1808: support NSEC for normal NXRRSET in in-memory

[BIND 10 Development]

#1808: support NSEC for normal NXRRSET in in-memory
-------------------------------------+-------------------------------------
            Reporter:  jinmei        |                        Owner:
                Type:  task          |                       Status:  new
            Priority:  medium        |                    Milestone:  New
           Component:  data source   |  Tasks
           Sensitive:  0             |                     Keywords:
         Sub-Project:  DNS           |              Defect Severity:  N/A
Estimated Difficulty:  0             |  Feature Depending on Ticket:  in-
         Total Hours:  0             |  memory NSEC
                                     |          Add Hours to Ticket:  0
                                     |                    Internal?:  0
-------------------------------------+-------------------------------------
 We'll update this case of InMemoryZoneFinder::find().  This is a "normal"
 NO DATA case.

 {{{#!c++
         // No exact match or CNAME.  Return NXRRSET.
         LOG_DEBUG(logger, DBG_TRACE_DATA, DATASRC_MEM_NXRRSET).arg(type).
             arg(name);
         return (createFindResult(NXRRSET, ConstRBNodeRRsetPtr(), rename));
 }}}

 In this case we can simply find NSEC for the matched node (we don't
 need getClosestNSEC()).  Note that it shouldn't do this extra work
 unless DNSSEC is required and the zone is known to be NSEC-signed
 (because the cost is not zero).

 Test both wildcard and non-wildcard cases.

 It depends on #1802, but otherwise can be done separately.

-- 
Ticket URL: <http://bind10.isc.org/ticket/1808>
BIND 10 Development <http://bind10.isc.org>
BIND 10 Development