[FS#217] nslookup behaving weirdly

[LEDE Bugs]

A new Flyspray task has been opened.  Details are below. 

User who did this - Karol Babioch (kbabioch) 

Attached to Project - LEDE Project
Summary - nslookup behaving weirdly
Task Type - Bug Report
Category - Base system
Status - Unconfirmed
Assigned To - 
Operating System - All
Severity - Low
Priority - Very Low
Reported Version - Trunk
Due in Version - Undecided
Due Date - Undecided
Details - Having built LEDE from source (a69e19d18ac0ebb3a715def18fed37026cae15af) I realized that nslookup (which is built into BusyBox) is behaving weirdly. Invoking it from command line via SSH I get an error message, although the name resolution is still working:

root at rtr1:~# nslookup google.com
nslookup: can't resolve '(null)': Name does not resolve

Name:      google.com
Address 1: 172.217.22.14 fra16s14-in-f14.1e100.net
Address 2: 2a00:1450:4001:817::200e fra16s08-in-x0e.1e100.net

Notice the error message: nslookup: can't resolve '(null)': Name does not resolve

This in itself is not too much of a problem, since the addresses returned are still ok. However, according to the "-h" parameter nslookup also has a second parameter:

root at rtr1:~# nslookup -h
BusyBox v1.25.0 () multi-call binary.

Usage: nslookup [HOST] [SERVER]

Query the nameserver for the IP address of the given HOST
optionally using a specified DNS server

The [SERVER] parameter can be used to query a specific name server. This does _NOT_ work. Regardless of what I put there, it is always the default resolver that is being queried. I am not able to query a specific nameserver, which in my case makes a difference (split horizon DNS).

For instance this query shouldn't return anything since my nameserver (ns1.babioch.de) is not configured to answer recursively:

root at rtr1:~# nslookup google.com ns1.babioch.de
Server:    10.24.0.10
Address 1: 10.24.0.10

Name:      google.com
Address 1: 2a00:1450:4001:817::200e fra16s08-in-x0e.1e100.net
Address 2: 172.217.16.206 fra16s08-in-f206.1e100.net

When doing this query with dig I get the proper result:

[kbabioch at antares ~]$ dig @ns1.babioch.de google.com

;  DiG 9.10.4-P3  @ns1.babioch.de google.com
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER