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Net::DNSNet::DNS is a DNS library written in pure Ruby. It started as a port of Perl Net::DNS module, but it evolved in time into a full Ruby library.
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Features-
Complete OO interface
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Clean and intuitive API
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Modular and flexible
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Requirements-
Ruby >= 1.8.6 (not tested with previous versions)
As of release TODO, Net::DNS is compatible with Ruby 1.9.1.
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InstallJust use RubyGems:
$ gem install net-dns
If you want to install from source, you can use Rake:
$ rake install
Or directly from setup.rb
$ ruby setup.rb
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API DocumentationVisit the page marcoceresa.com/net-dns
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Trivial resolverThe simplest way to use the library is to invoke the Resolver() method:
require 'rubygems' require 'net/dns/resolver' p Resolver("www.google.com")
The output is compatible with BIND zone files and it’s the same you would get with the dig utility.
;; Answer received from localhost:53 (212 bytes) ;; ;; HEADER SECTION ;; id = 64075 ;; qr = 1 opCode: QUERY aa = 0 tc = 0 rd = 1 ;; ra = 1 ad = 0 cd = 0 rcode = NoError ;; qdCount = 1 anCount = 3 nsCount = 4 arCount = 4 ;; QUESTION SECTION (1 record): ;; google.com. IN A ;; ANSWER SECTION (3 records): google.com. 212 IN A 74.125.45.100 google.com. 212 IN A 74.125.67.100 google.com. 212 IN A 209.85.171.100 ;; AUTHORITY SECTION (4 records): google.com. 345512 IN NS ns1.google.com. google.com. 345512 IN NS ns4.google.com. google.com. 345512 IN NS ns2.google.com. google.com. 345512 IN NS ns3.google.com. ;; ADDITIONAL SECTION (4 records): ns1.google.com. 170275 IN A 216.239.32.10 ns2.google.com. 170275 IN A 216.239.34.10 ns3.google.com. 170275 IN A 216.239.36.10 ns4.google.com. 170275 IN A 216.239.38.10
An optional block can be passed yielding the Net::DNS::Packet object
Resolver("www.google.com") {|packet| puts packet.size + " bytes"} #=> 484 bytes
Same for Net::DNS::Resolver.start():
Net::DNS::Resolver.start("google.com").answer.size #=> 5
As optional parameters, TYPE
and CLASS
can be specified.
p Net::DNS::Resolver.start("google.com", Net::DNS::MX) ;; Answer received from localhost:53 (316 bytes) ;; ;; HEADER SECTION ;; id = 59980 ;; qr = 1 opCode: QUERY aa = 0 tc = 0 rd = 1 ;; ra = 1 ad = 0 cd = 0 rcode = NoError ;; qdCount = 1 anCount = 4 nsCount = 4 arCount = 8 ;; QUESTION SECTION (1 record): ;; google.com. IN MX ;; ANSWER SECTION (4 records): google.com. 10800 IN MX 10 smtp2.google.com. google.com. 10800 IN MX 10 smtp3.google.com. google.com. 10800 IN MX 10 smtp4.google.com. google.com. 10800 IN MX 10 smtp1.google.com.
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Handling the response packetThe method Net::DNS::Resolver.start is a wrapper around Resolver.new. It returns a new Net::DNS::Packet object.
A DNS packet is divided into 5 sections:
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header section # => a Net::DNS::Header object
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question section # => a Net::DNS::Question object
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answer section # => an Array of Net::DNS::RR objects
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authority section # => an Array of Net::DNS::RR objects
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additional section # => an Array of Net::DNS::RR objects
You can access each section by calling the attribute with the same name on a Packet object:
packet = Net::DNS::Resolver.start("google.com") header = packet.header answer = packet.answer puts "The packet is #{packet.data.size} bytes" puts "It contains #{header.anCount} answer entries" answer.any? {|ans| p ans}
The output is
The packet is 378 bytes It contains 3 answer entries google.com. 244 IN A 74.125.45.100 google.com. 244 IN A 74.125.67.100 google.com. 244 IN A 209.85.171.100
A better way to handle the answer section is to use the iterators directly on a Packet object:
packet.each_address do |ip| puts "#{ip} is alive" if Ping.pingecho(ip.to_s, 10, 80) end
Gives:
74.125.45.100 is alive 74.125.67.100 is alive 209.85.171.100 is alive
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LicenceNet::DNS is distributed under the same license Ruby is.
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Author© Marco Ceresa 2006-2009