From cf8d1b5e411591dffed10cdc5ecfe78f95a63de1 Mon Sep 17 00:00:00 2001
From: Kazuki Yamaguchi <k@rhe.jp>
Date: Fri, 26 Mar 2021 16:52:08 +0900
Subject: [PATCH 1/3] Update test code for Resolv::DNS::Config ndots

Add more assertions to actually test that the ndots option is working
as expected: the option controls the threshold that the search list
should be attempted earlier or later.
---
 test/resolv/test_dns.rb | 28 ++++++++++++++++------------
 1 file changed, 16 insertions(+), 12 deletions(-)

diff --git a/test/resolv/test_dns.rb b/test/resolv/test_dns.rb
index d3c4b1f..a806841 100644
--- a/test/resolv/test_dns.rb
+++ b/test/resolv/test_dns.rb
@@ -25,18 +25,22 @@ def with_udp(host, port)
     end
   end
 
-  # [ruby-core:65836]
-  def test_resolve_with_2_ndots
-    conf = Resolv::DNS::Config.new :nameserver => ['127.0.0.1'], :ndots => 2
-    assert conf.single?
-
-    candidates = []
-    conf.resolv('example.com') { |candidate, *args|
-      candidates << candidate
-      raise Resolv::DNS::Config::NXDomain
-    }
-    n = Resolv::DNS::Name.create 'example.com.'
-    assert_equal n, candidates.last
+  def test_conf_ndots
+    # ndots defaults to 1
+    conf = Resolv::DNS::Config.new(nameserver: '127.0.0.1', search: ['local'])
+    conf.lazy_initialize
+    candidates = conf.generate_candidates('example.com')
+    assert_equal 2, candidates.size
+    assert_equal 'example.com', candidates[0].to_s
+    assert_equal 'example.com.local', candidates[1].to_s
+
+    # ndots is 2: search path is used first
+    conf = Resolv::DNS::Config.new(nameserver: '127.0.0.1', search: ['local'], ndots: 2)
+    conf.lazy_initialize
+    candidates = conf.generate_candidates('example.com')
+    assert_equal 2, candidates.size
+    assert_equal 'example.com.local', candidates[0].to_s
+    assert_equal 'example.com', candidates[1].to_s
   end
 
   def test_query_ipv4_address

From 15b9791937e1809104e044ee92b8e8cd3f7387a8 Mon Sep 17 00:00:00 2001
From: Kazuki Yamaguchi <k@rhe.jp>
Date: Fri, 26 Mar 2021 18:09:41 +0900
Subject: [PATCH 2/3] Fix querying absolute domain name twice

When search list is not explicitly specified, Resolv::DNS checks the
local domain name of the running system. If it is not set either, the
root domain ['.'] is used.

This is conceptually correct, but the code handles the absolute name
separately, which in turn creates a duplicate query.
---
 lib/resolv.rb           |  2 +-
 test/resolv/test_dns.rb | 15 +++++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/lib/resolv.rb b/lib/resolv.rb
index 3ca0f01..90e8951 100644
--- a/lib/resolv.rb
+++ b/lib/resolv.rb
@@ -1041,7 +1041,7 @@ def lazy_initialize
               if /\./ =~ hostname
                 @search = [Label.split($')]
               else
-                @search = [[]]
+                @search = []
               end
             end
 
diff --git a/test/resolv/test_dns.rb b/test/resolv/test_dns.rb
index a806841..a57ee88 100644
--- a/test/resolv/test_dns.rb
+++ b/test/resolv/test_dns.rb
@@ -43,6 +43,21 @@ def test_conf_ndots
     assert_equal 'example.com', candidates[1].to_s
   end
 
+  def test_conf_search
+    conf = Resolv::DNS::Config.new(nameserver: '127.0.0.1')
+    conf.lazy_initialize
+    candidates = conf.generate_candidates('example.com')
+    assert_equal candidates.size, candidates.uniq.size
+    assert_equal 'example.com', candidates[0].to_s
+
+    conf = Resolv::DNS::Config.new(nameserver: '127.0.0.1', search: ['local'])
+    conf.lazy_initialize
+    candidates = conf.generate_candidates('example.com')
+    assert_equal 2, candidates.size
+    assert_equal 'example.com', candidates[0].to_s
+    assert_equal 'example.com.local', candidates[1].to_s
+  end
+
   def test_query_ipv4_address
     begin
       OpenSSL

From f2d8beb90fff2ffb855c256224c6e6c0374e36c7 Mon Sep 17 00:00:00 2001
From: Kazuki Yamaguchi <k@rhe.jp>
Date: Fri, 26 Mar 2021 18:00:52 +0900
Subject: [PATCH 3/3] Tidy up ndots handling

The current code works, but the intention was not clear at first glance.
---
 lib/resolv.rb | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/lib/resolv.rb b/lib/resolv.rb
index 90e8951..7c7b9fb 100644
--- a/lib/resolv.rb
+++ b/lib/resolv.rb
@@ -1084,23 +1084,18 @@ def nameserver_port
       end
 
       def generate_candidates(name)
-        candidates = nil
         name = Name.create(name)
         if name.absolute?
-          candidates = [name]
+          [name]
         else
+          abs = Name.new(name.to_a)
+          search = @search.map {|domain| Name.new(name.to_a + domain)}
           if @ndots <= name.length - 1
-            candidates = [Name.new(name.to_a)]
+            [abs, *search]
           else
-            candidates = []
-          end
-          candidates.concat(@search.map {|domain| Name.new(name.to_a + domain)})
-          fname = Name.create("#{name}.")
-          if !candidates.include?(fname)
-            candidates << fname
+            [*search, abs]
           end
         end
-        return candidates
       end
 
       InitialTimeout = 5