Added Dns class for managing DNS search and nameservers

lib/linux_admin.rb

@@ -30,6 +30,7 @@
 require 'linux_admin/scap'
 require 'linux_admin/time_date'
 require 'linux_admin/ip_address'
+require 'linux_admin/dns'
 
 module LinuxAdmin
   extend Common

lib/linux_admin/dns.rb

@@ -0,0 +1,31 @@
+module LinuxAdmin
+  class Dns
+    attr_accessor :filename
+    attr_accessor :nameservers
+    attr_accessor :search_order
+
+    def initialize(filename = "/etc/resolv.conf")
+      @filename = filename
+      reload
+    end
+
+    def reload
+      @search_order = []
+      @nameservers  = []
+
+      File.read(@filename).split("\n").each do |line|
+        if line =~ /^search .*/
+          @search_order += line.split(/^search\s+/)[1].split
+        elsif line =~ /^nameserver .*/
+          @nameservers.push(line.split[1])
+        end
+      end
+    end
+
+    def save
+      contents = "search #{@search_order.join(" ")}\n"
+      @nameservers.each { |ns| contents += "nameserver #{ns}\n" }
+      File.write(@filename, contents)
+    end
+  end
+end

spec/dns_spec.rb

@@ -0,0 +1,75 @@
+describe LinuxAdmin::Dns do
+  RESOLV_CONF = <<DNS_END
+# Generated by NetworkManager
+search test.example.com test.two.example.com. example.com.
+nameserver 192.168.1.2
+nameserver 10.10.1.2
+nameserver 192.168.252.3
+DNS_END
+
+  SEARCH_ORDER = %w(test.example.com test.two.example.com. example.com.)
+  NAMESERVERS  = %w(192.168.1.2 10.10.1.2 192.168.252.3)
+
+  NEW_CONF = <<DNS_END
+search new.test.example.com other.test.example.com
+nameserver 192.168.3.4
+nameserver 10.10.11.12
+DNS_END
+
+  NEW_ORDER = %w(new.test.example.com other.test.example.com)
+  NEW_NS    = %w(192.168.3.4 10.10.11.12)
+
+  FILE = "/etc/dns_file"
+
+  subject do
+    allow(File).to receive(:read).and_return(RESOLV_CONF)
+    described_class.new(FILE)
+  end
+
+  describe ".new" do
+    it "sets the filename" do
+      expect(subject.filename).to eq(FILE)
+    end
+
+    it "parses the nameservers" do
+      expect(subject.nameservers).to eq(NAMESERVERS)
+    end
+
+    it "parses the search order" do
+      expect(subject.search_order).to eq(SEARCH_ORDER)
+    end
+  end
+
+  describe "#reload" do
+    it "reloads the nameservers" do
+      expect(subject.nameservers).to eq(NAMESERVERS)
+
+      allow(File).to receive(:read).and_return(NEW_CONF)
+      subject.reload
+
+      expect(subject.nameservers).to eq(NEW_NS)
+    end
+
+    it "reloads the search order" do
+      expect(subject.search_order).to eq(SEARCH_ORDER)
+
+      allow(File).to receive(:read).and_return(NEW_CONF)
+      subject.reload
+
+      expect(subject.search_order).to eq(NEW_ORDER)
+    end
+  end
+
+  describe "#save" do
+    it "writes the correct contents" do
+      expect(File).to receive(:write) do |file, contents|
+        expect(file).to eq(subject.filename)
+        expect(contents).to eq(NEW_CONF)
+      end
+
+      subject.search_order = NEW_ORDER
+      subject.nameservers = NEW_NS
+      subject.save
+    end
+  end
+end