[ruby/cgi] Loosen the domain regex to accept '.'

(https://github.com/ruby/cgi/pull/29)

* Loosen the domain regex to accept '.'

Co-authored-by: Nobuyoshi Nakada <nobu@ruby-lang.org>

https://github.com/ruby/cgi/commit/5e09d632f3
Co-authored-by: Hiroshi SHIBATA <hsbt@ruby-lang.org>

lib/cgi/cookie.rb

@@ -42,7 +42,7 @@ class CGI
 
     TOKEN_RE = %r"\A[[!-~]&&[^()<>@,;:\\\"/?=\[\]{}]]+\z"
     PATH_VALUE_RE = %r"\A[[ -~]&&[^;]]*\z"
-    DOMAIN_VALUE_RE = %r"\A(?<label>(?!-)[-A-Za-z0-9]+(?<!-))(?:\.\g<label>)*\z"
+    DOMAIN_VALUE_RE = %r"\A\.?(?<label>(?!-)[-A-Za-z0-9]+(?<!-))(?:\.\g<label>)*\z"
 
     # Create a new CGI::Cookie object.
     #

test/cgi/test_cgi_cookie.rb

@@ -65,6 +65,9 @@ class CGICookieTest < Test::Unit::TestCase
     cookie = CGI::Cookie.new(h.merge('domain'=>'a.example.com'))
     assert_equal('a.example.com', cookie.domain)
 
+    cookie = CGI::Cookie.new(h.merge('domain'=>'.example.com'))
+    assert_equal('.example.com', cookie.domain)
+
     cookie = CGI::Cookie.new(h.merge('domain'=>'1.example.com'))
     assert_equal('1.example.com', cookie.domain, 'enhanced by RFC 1123')