BIND 10 #1807: support NSEC for empty non-terminal in in-memory (2/2)

[BIND 10 Development]

#1807: support NSEC for empty non-terminal in in-memory (2/2)
-------------------------------------+-------------------------------------
            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().  it's another empty
 non terminal case (may or may not be wildcard)

 {{{#!c++
         // If there is an exact match but the node is empty, it's
 equivalent
         // to NXRRSET.
         if (node->isEmpty()) {
             LOG_DEBUG(logger, DBG_TRACE_DATA, DATASRC_MEM_DOMAIN_EMPTY).
                 arg(name);
             return (createFindResult(NXRRSET, ConstRBNodeRRsetPtr(),
 rename));
         }
 }}}

 It uses getClosestNSEC() to get the NSEC for the previous name of the
 empty name and includes it in the answer.  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.

 Depends on #1803 and #1805 (no need for #1804).

-- 
Ticket URL: <http://bind10.isc.org/ticket/1807>
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