[latch]

Diving a little deeper down:

1 - A websocket "frame" has a variable-length header. Client->Server the header can be 6, 8 or 14 bytes. Server->Client it can be 2, 4 or 10. This is to support payloads < 125 bytes, < 2^16 and up to 2^64. I wish it was just a fixed 4-byte length.

2 - Frames can be fragmented to support streaming (where the sender or possibly a proxy doesn't know/want to buffer the entire response ahead of time). I feel like this is unnecessary in 99% of the cases. It wouldn't be so annoying..except control frames can be interspersed within fragmented frames. This is so that you can send a "ping" while streaming a large message over multiple fragments. Why didn't they just use one of those reserved bits for this?

3 - Client->Server payload is masked with 4 bytes (bitwise xor) so every message your server gets has to be unmasked.