node rpc: validateresource

[tynes]

This PR adds a new Node RPC method called validateresource. It is useful for users who are in the process of creating their resource JSON to use with sendupdate. This PR adds error messages in the fromJSON methods of each of the records found in lib/dns/resource.js.

The RPC accepts a single object with the records property, which must be an array of objects.
Eventually, it could also accept a version property if another Resource version is implemented.

The error messages note the invalid JSON property name and the record type. This is so that good error messages can be returned to users. The error messages could be made generic (not including the record type in the error message) but that would mean that the RPC method handler itself would have to hold logic similar to Resource.fromJSON and keep track of which record failed its fromJSON. I don't like this approach as much since any new resource type will require its fromJSON logic to be added to the RPC method handler but am willing to update this PR if people are strongly opinionated in that way.

Closes #139

[pinheadmz]

Looks pretty good, playing with the branch locally and might add a test.

Do you think some of these error message could be even more specific?
e.g.
TXT record "txt" must be an array
Resource "records" must be an array
Resource "records" items must be objects
DS record keyType must be int < 0xffff
DS record "digest" must be string
etc

[boymanjor]

Looks pretty good, playing with the branch locally and might add a test.

Do you think some of these error message could be even more specific?
e.g.
TXT record "txt" must be an array
Resource "records" must be an array
Resource "records" items must be objects
DS record keyType must be int < 0xffff
DS record "digest" must be string
etc

How about Invalid DS record. Property "json" must be an Array.

[tynes]

New commits pushed up, I followed similar error messaging to @boymanjor's suggestion here:
DS record "digest" must be string

[tynes]

This is ready for another round of review. I wrote tests for both success and failure cases.

[codecov-io]

Codecov Report

Merging #429 into master will increase coverage by 0.01%.
The diff coverage is 95.45%.

@@            Coverage Diff             @@
##           master     #429      +/-   ##
==========================================
+ Coverage   61.97%   61.98%   +0.01%     
==========================================
  Files         129      129              
  Lines       34831    34843      +12     
  Branches     5918     5920       +2     
==========================================
+ Hits        21587    21598      +11     
- Misses      13244    13245       +1     

Impacted Files	Coverage Δ
lib/node/rpc.js	28.30% <83.33%> (+0.66%)	⬆️
lib/dns/resource.js	84.77% <100.00%> (ø)
lib/utils/binary.js	56.41% <0.00%> (-2.57%)	⬇️
lib/protocol/consensus.js	87.75% <0.00%> (-1.03%)	⬇️
lib/covenants/rules.js	73.04% <0.00%> (-0.15%)	⬇️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 2d5ab27...0b147e1. Read the comment docs.

[pinheadmz]

Great work on this dude, thanks for the thorough test. Only thing left for me is the help message.

[pinheadmz]

ACK @ d5d9821