baze utilities: shost

I covered how to install baze and introduced suc two days ago, then statistik yesterday. Today, we're looking at shost.

Looking to resolve DNS names? bind ships host and dig, ldns ships drill.

shost is quite terse in comparison:

> shost ident.me
2a01:4f8:c0c:bd0a::1
49.12.234.183
> host ident.me
ident.me has address 49.12.234.183
ident.me has IPv6 address 2a01:4f8:c0c:bd0a::1
> drill ident.me
;; ->>HEADER<<- opcode: QUERY, rcode: NOERROR, id: 15200
;; flags: qr rd ra ; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;; ident.me.    IN      A

;; ANSWER SECTION:
ident.me.       12      IN      A       49.12.234.183

;; AUTHORITY SECTION:

;; ADDITIONAL SECTION:

;; Query time: 4 msec
;; SERVER: 100.100.100.100
;; WHEN: Mon Sep 23 17:24:40 2024
;; MSG SIZE  rcvd: 42
> dig ident.me

; <<>> DiG 9.10.6 <<>> ident.me
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 28298
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4095
;; QUESTION SECTION:
;ident.me.                      IN      A

;; ANSWER SECTION:
ident.me.               11      IN      A       49.12.234.183

;; Query time: 4 msec
;; SERVER: 100.100.100.100#53(100.100.100.100)
;; WHEN: Mon Sep 23 17:24:41 CEST 2024
;; MSG SIZE  rcvd: 53

>

It has the benefit of letting you reverse lookup in one go:

> shost -r ident.me
v6.ident.me
v4.ident.me

host, dig and drill all resolve names through their respective DNS implementation.

shost doesn't compete but completes, relying on the system's resolver instead.

So, while a lot less information is available about what happens in DNS, what you get back is what most software uses. For example, .local names are looked up through mDNS/zeroconf if your operating system is configured to do so:

pcarrier@cat ~> shost cat.local
::1
fe80::1%lo0
127.0.0.1
192.168.1.21
192.168.42.142
fe80::1cfa:8a61:53e2:5324%en0
fe80::1ce2:3342:8435:7cd7%en3
2a01:e0a:250:7160:482:db55:6b74:b323

This makes it a valuable addition to a troubleshooter's toolbox.

As usual in baze, very little code:

#!/usr/bin/env ruby

require 'socket'
require 'optparse'

reverse = false
soft = false

optparse = OptionParser.new do |opts|
  opts.banner = "Usage: shost [-r] host...\n" \
    "  Resolves names"

  opts.on '-r', '--reverse', 'Display reverse lookups' do
    reverse = true
  end
  opts.on '-s', '--softfail', 'Simply display failures instead of exiting' do
    soft = true
  end
end

optparse.parse!

raise 'host expected' if ARGV.empty?

ARGV.each do |host|
  begin
    infos = Socket.getaddrinfo(host, nil, Socket::AF_UNSPEC, Socket::SOCK_STREAM, nil, 0, reverse)

    if reverse
      infos.each {|r| puts r[2]}
    else
      infos.each {|r| puts r[3]}
    end
  rescue SocketError => e
    if soft
      STDERR.puts "#{host} FAILED"
    else
      raise e
    end
  end
end