1 files changed, 71 insertions, 0 deletions
diff --git a/activesupport/lib/active_support/messages/metadata.rb b/activesupport/lib/active_support/messages/metadata.rb
new file mode 100644
index 0000000000..e97caac766
--- /dev/null
+++ b/activesupport/lib/active_support/messages/metadata.rb
@@ -0,0 +1,71 @@
+# frozen_string_literal: true
+
+require "time"
+
+module ActiveSupport
+  module Messages #:nodoc:
+    class Metadata #:nodoc:
+      def initialize(message, expires_at = nil, purpose = nil)
+        @message, @expires_at, @purpose = message, expires_at, purpose
+      end
+
+      def as_json(options = {})
+        { _rails: { message: @message, exp: @expires_at, pur: @purpose } }
+      end
+
+      class << self
+        def wrap(message, expires_at: nil, expires_in: nil, purpose: nil)
+          if expires_at || expires_in || purpose
+            JSON.encode new(encode(message), pick_expiry(expires_at, expires_in), purpose)
+          else
+            message
+          end
+        end
+
+        def verify(message, purpose)
+          extract_metadata(message).verify(purpose)
+        end
+
+        private
+          def pick_expiry(expires_at, expires_in)
+            if expires_at
+              expires_at.utc.iso8601(3)
+            elsif expires_in
+              Time.now.utc.advance(seconds: expires_in).iso8601(3)
+            end
+          end
+
+          def extract_metadata(message)
+            data = JSON.decode(message) rescue nil
+
+            if data.is_a?(Hash) && data.key?("_rails")
+              new(decode(data["_rails"]["message"]), data["_rails"]["exp"], data["_rails"]["pur"])
+            else
+              new(message)
+            end
+          end
+
+          def encode(message)
+            ::Base64.strict_encode64(message)
+          end
+
+          def decode(message)
+            ::Base64.strict_decode64(message)
+          end
+      end
+
+      def verify(purpose)
+        @message if match?(purpose) && fresh?
+      end
+
+      private
+        def match?(purpose)
+          @purpose.to_s == purpose.to_s
+        end
+
+        def fresh?
+          @expires_at.nil? || Time.now.utc < Time.iso8601(@expires_at)
+        end
+    end
+  end
+end