WebSockets

permessage-deflate support

• Is this something we need/want to support? Servers that are setup correctly should work even if the client doesn't support it.
• Memory fragmentation issues when using zlib?
• Added complexity of decompressing frames asynchronously

Performance

• Consume the least amount of bytes possible, rather than concatenating every chunk available. See ws' implementation. Fixed in 5165d6712088c41ebbf66cf71ba856924008e899
• Switch to Buffer.allocUnsafe in lib/websocket/frame.js Fixed in b6844f08037cf59bc864a947466756e72c895d92
• Handle TODO comments labeled as "optimize this".
• Benchmarks
• Use FastBuffer (Buffer[Symbol.species])

Tests

• Add ws' test suite. Note this isn't easy because ws' api does not strictly follow the spec and it occasionally uses internal, underscored properties. Also note that a lot of the validation tests are already handled by the WPTs.
• Autobahn testsuite
• 100% code coverage for lib/websockets Code coverage is high enough; WPTs are not counted, which make up a majority of the tests.
• Test more strange/error conditions:
  • Chunks that contain thousands of frames
  • Chunks that receive a pong/close frame in the middle of a fragmented message (Control frames are already handled the same.)
  • Sending invalid frames

Bugs

• using WebSocket.send with a Blob asynchronously writes the blob data to the socket. This can cause issues when concurrently sending a blob with anything else. Note: we need support in node core to read a Blob synchronously.
• ByteParser.run runs recursively, meaning the max call stack can be exceeded under certain conditions (ie. receiving thousands of frames in a single chunk). Fixed in 1b858fbcaec4e97550a95038469b1e1d0c979340

Features

• Setting an undici Dispatcher rather than using the global dispatcher by default.
• Letting the client generate the mask for performance reasons.

WebSocketStream

• https://github.com/ricea/websocketstream-explainer
• No real spec, the explainer is superficial.
• API is much better; allows for expansion (ie. second param is a dictionary rather than a list/string).
• Probably much slower
• requires rewrite of WebSocket internals

This is a broad WebSocket tracking issue with several completed items and no single remaining scope. Review the unchecked permessage-deflate, Blob-send, benchmarking, and mask-generation points, starting with lib/websocket/frame.js and the current WebSocket entry points; done requires choosing one item, defining its tests, and confirming that focused behavior.