* lib/base64.rb: make urlsafe mode user-friendly.

* lib/base64.rb (Base64.urlsafe_encode64): a new option "padding" to
  suppress the padding character ("=").

* lib/base64.rb (Base64.urlsafe_decode64): now it accepts not only
  correctly-padded input but also unpadded input.
  [Feature #10740][ruby-core:67570]

* test/base64/test_base64.rb: Test for above

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@49585 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,16 @@
+Fri Feb 13 21:16:00 2015  Yusuke Endoh  <mame@tsg.ne.jp>
+
+	* lib/base64.rb: make urlsafe mode user-friendly.
+
+	* lib/base64.rb (Base64.urlsafe_encode64): a new option "padding" to
+	  suppress the padding character ("=").
+
+	* lib/base64.rb (Base64.urlsafe_decode64): now it accepts not only
+	  correctly-padded input but also unpadded input.
+	  [Feature #10740][ruby-core:67570]
+
+	* test/base64/test_base64.rb: Test for above
+
 Fri Feb 13 14:19:06 2015  SHIBATA Hiroshi  <shibata.hiroshi@gmail.com>
 
 	* ext/json: merge upstream from flori/json

NEWS

@@ -38,6 +38,12 @@ with all sufficient information, see the ChangeLog file.
 * lib/drb/drb.rb
  * removed unused argument. https://github.com/ruby/ruby/pull/515
 
+* lib/base64.rb
+ * Base64.urlsafe_encode64: added a "padding" option to suppress
+   the padding character ("=").
+ * Base64.urlsafe_decode64: now it accepts not only correctly-padded
+   input but also unpadded input.
+
 === Built-in global variables compatibility issues
 
 === C API updates

lib/base64.rb

@@ -77,15 +77,30 @@ module Base64
   # This method complies with ``Base 64 Encoding with URL and Filename Safe
   # Alphabet'' in RFC 4648.
   # The alphabet uses '-' instead of '+' and '_' instead of '/'.
-  def urlsafe_encode64(bin)
-    strict_encode64(bin).tr("+/", "-_")
+  # Note that the result can still contain '='.
+  # You can remove the padding by setting "padding" as false.
+  def urlsafe_encode64(bin, padding: true)
+    str = strict_encode64(bin).tr("+/", "-_")
+    str = str.delete("=") unless padding
+    str
   end
 
   # Returns the Base64-decoded version of +str+.
   # This method complies with ``Base 64 Encoding with URL and Filename Safe
   # Alphabet'' in RFC 4648.
   # The alphabet uses '-' instead of '+' and '_' instead of '/'.
+  #
+  # The padding character is optional.
+  # This method accepts both correctly-padded and unpadded input.
+  # Note that it still rejects incorrectly-padded input.
   def urlsafe_decode64(str)
-    strict_decode64(str.tr("-_", "+/"))
+    # NOTE: RFC 4648 does say nothing about unpadded input, but says that
+    # "the excess pad characters MAY also be ignored", so it is inferred that
+    # unpadded input is also acceptable.
+    str = str.tr("-_", "+/")
+    if !str.end_with?("=") && str.length % 4 != 0
+      str = str.ljust((str.length + 3) & ~3, "=")
+    end
+    strict_decode64(str)
   end
 end

test/base64/test_base64.rb

@@ -87,6 +87,13 @@ class TestBase64 < Test::Unit::TestCase
     assert_equal("_-8=", Base64.urlsafe_encode64("\xff\xef"))
   end
 
+  def test_urlsafe_encode64_unpadded
+    assert_equal("", Base64.urlsafe_encode64("", padding: false))
+    assert_equal("AA", Base64.urlsafe_encode64("\0", padding: false))
+    assert_equal("AAA", Base64.urlsafe_encode64("\0\0", padding: false))
+    assert_equal("AAAA", Base64.urlsafe_encode64("\0\0\0", padding: false))
+  end
+
   def test_urlsafe_decode64
     assert_equal("", Base64.urlsafe_decode64(""))
     assert_equal("\0", Base64.urlsafe_decode64("AA=="))
@@ -97,4 +104,11 @@ class TestBase64 < Test::Unit::TestCase
     assert_equal("\377\377\377", Base64.urlsafe_decode64("____"))
     assert_equal("\xff\xef", Base64.urlsafe_decode64("_+8="))
   end
+
+  def test_urlsafe_decode64_unpadded
+    assert_equal("\0", Base64.urlsafe_decode64("AA"))
+    assert_equal("\0\0", Base64.urlsafe_decode64("AAA"))
+    assert_equal("\0\0\0", Base64.urlsafe_decode64("AAAA"))
+    assert_raise(ArgumentError) { Base64.urlsafe_decode64("AA=") }
+  end
 end