Handle unbracketed ipv6 addresses (#538)

* Add failing test
* Parse unbracketed ipv6 hosts with no ports
* Tweak style

lib/sshkit/host.rb

@@ -1,4 +1,5 @@
 require 'ostruct'
+require 'resolv'
 
 module SSHKit
 
@@ -122,6 +123,22 @@ def attributes
 
   end
 
+  # @private
+  # :nodoc:
+  class IPv6HostParser < SimpleHostParser
+    def self.suitable?(host_string)
+      host_string.match(Resolv::IPv6::Regex)
+    end
+
+    def port
+
+    end
+
+    def hostname
+      @host_string.match(Resolv::IPv6::Regex)[0]
+    end
+  end
+
   class HostWithPortParser < SimpleHostParser
 
     def self.suitable?(host_string)
@@ -192,6 +209,7 @@ def hostname
 
   PARSERS = [
     SimpleHostParser,
+    IPv6HostParser,
     HostWithPortParser,
     HostWithUsernameAndPortParser,
     IPv6HostWithPortParser,

test/unit/test_host.rb

@@ -28,6 +28,12 @@ def test_host_with_port
       assert_equal 'example.com', h.hostname
     end
 
+    def test_custom_host_with_port
+      h = Host.new 'db:22'
+      assert_equal 22,   h.port
+      assert_equal 'db', h.hostname
+    end
+
     def test_host_with_username
       h = Host.new '[email protected]'
       assert_equal 'root',        h.username
@@ -50,6 +56,12 @@ def test_host_local
       assert_equal 'localhost',         h.hostname
     end
 
+    def test_ipv6_without_brackets
+      h = Host.new '1fff:0:a88:85a3::ac1f'
+      assert_nil h.port
+      assert_equal '1fff:0:a88:85a3::ac1f', h.hostname
+    end
+
     def test_does_not_confuse_ipv6_hosts_with_port_specification
       h = Host.new '[1fff:0:a88:85a3::ac1f]:8001'
       assert_equal 8001,                    h.port