Use IO::Buffer for masking.

.github/workflows/coverage.yaml

@@ -21,6 +21,7 @@ jobs:
           - macos
 
         ruby:
+          - "3.1"
           - "3.2"
 
     steps:

benchmark/mask_xor.rb

@@ -0,0 +1,53 @@
+def mask_xor_buffer(data, mask)
+	buffer = data.dup
+	mask_buffer = IO::Buffer.for(mask)
+
+	IO::Buffer.for(buffer) do |buffer|
+		buffer.xor!(mask_buffer)
+	end
+
+	return buffer
+end
+
+def mask_xor_string(data, mask)
+	result = String.new(encoding: Encoding::BINARY)
+
+	for i in 0...data.bytesize do
+		result << (data.getbyte(i) ^ mask.getbyte(i % 4))
+	end
+
+	return result
+end
+
+require 'benchmark/ips'
+require 'securerandom'
+
+MASK = SecureRandom.bytes(4)
+DATA = SecureRandom.bytes(1024 * 1024)
+
+Benchmark.ips do |x|
+  # Configure the number of seconds used during
+  # the warmup phase (default 2) and calculation phase (default 5)
+  x.config(:time => 5, :warmup => 2)
+
+  # These parameters can also be configured this way
+  x.time = 5
+  x.warmup = 2
+
+	x.report("IO::Buffer") {mask_xor_buffer(DATA, MASK)}
+	x.report("String") {mask_xor_string(DATA, MASK)}
+
+  # Compare the iterations per second of the various reports!
+  x.compare!
+end
+
+# Warming up --------------------------------------
+#           IO::Buffer   152.000  i/100ms
+#               String     1.000  i/100ms
+# Calculating -------------------------------------
+#           IO::Buffer      1.534k (± 0.1%) i/s -      7.752k in   5.051915s
+#               String     11.929  (± 0.0%) i/s -     60.000  in   5.029975s
+
+# Comparison:
+#           IO::Buffer:     1534.5 i/s
+#               String:       11.9 i/s - 128.63x  slower

lib/protocol/websocket/frame.rb

@@ -86,6 +86,30 @@ def continued?
 			attr_accessor :length
 			attr_accessor :payload
 
+			if IO.const_defined?(:Buffer) && IO::Buffer.respond_to?(:for) && IO::Buffer.method_defined?(:xor!)
+				private def mask_xor(data, mask)
+					buffer = data.dup
+					mask_buffer = IO::Buffer.for(mask)
+
+					IO::Buffer.for(buffer) do |buffer|
+						buffer.xor!(mask_buffer)
+					end
+
+					return buffer
+				end
+			else
+				warn "IO::Buffer not available, falling back to slow implementation of mask_xor!"
+				private def mask_xor(data, mask)
+					result = String.new(encoding: Encoding::BINARY)
+
+					for i in 0...data.bytesize do
+						result << (data.getbyte(i) ^ mask.getbyte(i % 4))
+					end
+
+					return result
+				end
+			end
+
 			def pack(data = "")
 				length = data.bytesize
 
@@ -94,12 +118,7 @@ def pack(data = "")
 				end
 
 				if @mask
-					@payload = String.new(encoding: Encoding::BINARY)
-
-					for i in 0...data.bytesize do
-						@payload << (data.getbyte(i) ^ mask.getbyte(i % 4))
-					end
-
+					@payload = mask_xor(data, mask)
 					@length = length
 				else
 					@payload = data
@@ -111,13 +130,7 @@ def pack(data = "")
 
 			def unpack
 				if @mask and !@payload.empty?
-					data = String.new(encoding: Encoding::BINARY)
-
-					for i in 0...@payload.bytesize do
-						data << (@payload.getbyte(i) ^ @mask.getbyte(i % 4))
-					end
-
-					return data
+					return mask_xor(@payload, @mask)
 				else
 					return @payload
 				end