Added nameserver class for nameservers option

Author: taketo1113

lib/ddig.rb

@@ -1,6 +1,7 @@
 # frozen_string_literal: true
 
 require_relative "ddig/version"
+require_relative "ddig/nameserver"
 require_relative "ddig/resolver/do53"
 require_relative "ddig/resolver/dot"
 require_relative "ddig/ddr"
@@ -12,8 +13,10 @@ def self.lookup(hostname, nameservers: nil)
     @hostname = hostname
     @nameservers = nameservers
 
-    @do53_ipv4 = Ddig::Resolver::Do53.new(hostname: @hostname, nameservers: @nameservers, ip: :ipv4).lookup
-    @do53_ipv6 = Ddig::Resolver::Do53.new(hostname: @hostname, nameservers: @nameservers, ip: :ipv6).lookup
+    @nameserver = Ddig::Nameserver.new(nameservers: @nameservers)
+
+    @do53_ipv4 = Ddig::Resolver::Do53.new(hostname: @hostname, nameservers: @nameserver.servers, ip: :ipv4).lookup
+    @do53_ipv6 = Ddig::Resolver::Do53.new(hostname: @hostname, nameservers: @nameserver.servers, ip: :ipv6).lookup
 
     @ddr = Ddig::Ddr.new(nameservers: @nameservers)
 

lib/ddig/nameserver.rb

@@ -0,0 +1,49 @@
+require 'resolv'
+
+module Ddig
+  class Nameserver
+    attr_reader :servers
+
+    def initialize(nameservers: nil)
+      @nameservers = nameservers
+
+      if @nameservers.nil?
+        @servers = default_servers
+      elsif @nameservers.is_a?(Array)
+        @servers = @nameservers
+      else
+        @servers = [@nameservers]
+      end
+
+      validation_servers
+    end
+
+    def servers
+      if @servers.count.zero?
+        raise Ddig::Error.new('nameservers required')
+      end
+
+      @servers
+    end
+
+    def default_servers
+      Resolv::DNS::Config.default_config_hash[:nameserver]
+    end
+
+    def validation_servers
+      @servers.uniq.each do |server|
+        addr = IPAddr.new(server) rescue nil
+        if addr.nil?
+          puts "Warning: nameservers has invalid ip address (nameserver: #{server})"
+          @servers.delete(server)
+        end
+      end
+
+      if @servers.count.zero?
+        return false
+      end
+
+      return true
+    end
+  end
+end

spec/ddig/nameserver_spec.rb

@@ -0,0 +1,53 @@
+# frozen_string_literal: true
+
+RSpec.describe Ddig::Nameserver do
+  context "#servers" do
+    it "return nameservers with namesevers" do
+      @nameserver = Ddig::Nameserver.new(nameservers: ['8.8.8.8'])
+
+      expect(@nameserver.servers).to eq ['8.8.8.8']
+    end
+
+    it "return nameservers with string value of namesevers" do
+      @nameserver = Ddig::Nameserver.new(nameservers: '8.8.8.8')
+
+      expect(@nameserver.servers).to eq ['8.8.8.8']
+    end
+
+    it "return default nameservers without namesevers" do
+      @nameserver = Ddig::Nameserver.new()
+
+      expect(@nameserver.servers.count).not_to eq 0
+    end
+
+    it "return default nameservers with nil value of namesevers" do
+      @nameserver = Ddig::Nameserver.new(nameservers: nil)
+
+      expect(@nameserver.servers.count).not_to eq 0
+    end
+
+    it "raise error when nameservers is blank" do
+      @nameserver = Ddig::Nameserver.new(nameservers: [])
+
+      expect{
+        @nameserver.servers
+      }.to raise_error(Ddig::Error)
+    end
+
+    context "with invalid value of namesevers" do
+      it "return only valid nameservers with valid and invalid value of nameservers" do
+        @nameserver = Ddig::Nameserver.new(nameservers: ['invalid', '8.8.8.8'])
+
+        expect(@nameserver.servers).to eq ['8.8.8.8']
+      end
+
+      it "raise error when nameservers is blank" do
+        @nameserver = Ddig::Nameserver.new(nameservers: ['invalid'])
+
+        expect{
+          @nameserver.servers
+        }.to raise_error(Ddig::Error)
+      end
+    end
+  end
+end