No results from asn-query.nse

[David Fifield <david () bamsoftware com>]

I'm using r37617. The asn-query script outputs "No Answers", and the
debug output says:
NSE: [asn-query 45.33.32.156] dns.answerFetcher found no records of the required type: TXT
NSE: [asn-query 45.33.32.156] Error from dns.query(): No Answers

```
$ nmap -d -Pn -sn --dns-servers=1.1.1.1 --script=asn-query scanme.nmap.org
Host discovery disabled (-Pn). All addresses will be marked 'up' and scan times may be slower.
Starting Nmap 7.94SVN ( https://nmap.org ) at 2023-06-04 17:57 UTC
--------------- Timing report ---------------
  hostgroups: min 1, max 100000
  rtt-timeouts: init 1000, min 100, max 10000
  max-scan-delay: TCP 1000, UDP 1000, SCTP 1000
  parallelism: min 0, max 0
  max-retries: 10, host-timeout: 0
  min-rate: 0, max-rate: 0
---------------------------------------------
NSE: Using Lua 5.4.
NSE: Arguments from CLI:
NSE: Loaded 1 scripts for scanning.
NSE: Script Pre-scanning.
NSE: Starting runlevel 1 (of 1) scan.
Initiating NSE at 17:57
Completed NSE at 17:57, 0.00s elapsed
mass_rdns: Using DNS server 1.1.1.1
Initiating Parallel DNS resolution of 1 host. at 17:57
mass_rdns: 0.15s 0/1 [#: 1, OK: 0, NX: 0, DR: 0, SF: 0, TR: 1]
Completed Parallel DNS resolution of 1 host. at 17:57, 0.15s elapsed
DNS resolution of 1 IPs took 0.15s. Mode: Async [#: 1, OK: 1, NX: 0, DR: 0, SF: 0, TR: 1, CN: 0]
NSE: Script scanning 45.33.32.156.
NSE: Starting runlevel 1 (of 1) scan.
Initiating NSE at 17:57
NSE: Starting asn-query against scanme.nmap.org (45.33.32.156).
NSE: [asn-query 45.33.32.156] dns.answerFetcher found no records of the required type: TXT
NSE: [asn-query 45.33.32.156] Error from dns.query(): No Answers
NSE: Finished asn-query against scanme.nmap.org (45.33.32.156).
Completed NSE at 17:57, 0.14s elapsed
Nmap scan report for scanme.nmap.org (45.33.32.156)
Host is up, received user-set.
Other addresses for scanme.nmap.org (not scanned): 2600:3c01::f03c:91ff:fe18:bb2f

Host script results:
|_asn-query: No Answers

NSE: Script Post-scanning.
NSE: Starting runlevel 1 (of 1) scan.
Initiating NSE at 17:57
Completed NSE at 17:57, 0.00s elapsed
No data files read.
Nmap done: 1 IP address (1 host up) scanned in 0.62 seconds
```

Looking at a packet capture, I can see that a DNS response is received
with a TXT record in the Answer section. I also get a response if I do
the query manually following https://www.team-cymru.com/ip-asn-mapping#dns.

```
$ dig @1.1.1.1 156.32.33.45.nmap.asn.cymru.com TXT

; <<>> DiG 9.16.37-Debian <<>> @1.1.1.1 156.32.33.45.nmap.asn.cymru.com TXT
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 20388
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 1232
;; QUESTION SECTION:
;156.32.33.45.nmap.asn.cymru.com. IN    TXT

;; ANSWER SECTION:
156.32.33.45.nmap.asn.cymru.com. 14400 IN TXT   "63949 | 45.33.32.0/19 | US | arin | 2015-03-20"

;; Query time: 179 msec
;; SERVER: 1.1.1.1#53(1.1.1.1)
;; WHEN: Sun Jun 04 17:57:53 UTC 2023
;; MSG SIZE  rcvd: 119
```
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