* 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

1 files changed, 18 insertions, 3 deletions

diff --git a/lib/base64.rb b/lib/base64.rb
index 98829f0d96..30304cd188 100644
--- a/lib/base64.rb
+++ b/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