BIND 10 #1575: move data_source.cc:Nsec3Param to libdns++

[BIND 10 Development]

#1575: move data_source.cc:Nsec3Param to libdns++
-------------------------------------+-------------------------------------
            Reporter:  jinmei        |                        Owner:
                Type:  task          |  UnAssigned
            Priority:  major         |                       Status:  new
           Component:  libdns++      |                    Milestone:  Next-
           Sensitive:  0             |  Sprint-Proposed
         Sub-Project:  DNS           |                     Keywords:
Estimated Difficulty:  0             |              Defect Severity:  N/A
         Total Hours:  0             |  Feature Depending on Ticket:  NSEC3
                                     |          Add Hours to Ticket:  0
                                     |                    Internal?:  0
-------------------------------------+-------------------------------------
 We'll need a public interface to calculating a hashed name based on
 NSEC3 params in order to support NSEC3 in a wider place (specifically
 in the new in memory and database data source implementations).

 The more appropriate place would be libdns++, as this calculation
 is independent from data sources (and we'll probably need it in future
 for the validator).  We should also eventually use botan for the hash
 implementation and deprecate our in-house copy.  But that's probably a
 future task.

 To me this doesn't seem to have to be a class since it doesn't need
 any intermediate state, but that's probably a matter of taste.

 We'll also need more tests, and be more careful about corner cases
 (such as against unknown algorithms - the current implementation
 naively assumes it's sha-1 while accepting a generic algorithm
 parameter).

-- 
Ticket URL: <http://bind10.isc.org/ticket/1575>
BIND 10 Development <http://bind10.isc.org>
BIND 10 Development