nx_websocket.nx

nx_websocket.nx -- RFC 6455 server-side WebSocket primitive. Pure NishiLang. No external library. Composes nx_sha1 and nx_base64 (both already shipped) for the handshake; implements the binary framing (opcodes, masking, payload-length variants) from the RFC text. Server-side flow: 1. Client sends: GET /ws HTTP/1.1 Upgrade: websocket Connection: Upgrade Sec-WebSocket-Key: <base64 16-byte nonce> Sec-WebSocket-Version: 13 We compute Sec-WebSocket-Accept = base64(sha1(key + GUID)) where GUID = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11" (RFC 6455 section 1.3). 2. Reply: HTTP/1.1 101 Switching Protocols Upgrade: websocket Connection: Upgrade Sec-WebSocket-Accept: <accept> 3. Subsequent traffic is binary frames. Frame layout (most-common case; mask MUST be present for client->server): [byte 0] FIN (1) | RSV (3) | OPCODE (4) [byte 1] MASK (1) | LEN7 (7) LEN7 in 0..125: payload length is LEN7 LEN7 == 126: next 2 bytes (big-endian) are payload length LEN7 == 127: next 8 bytes (big-endian) are payload length [4 bytes] masking-key (when MASK=1) [N bytes] payload (XORed with masking-key when MASK=1) Common opcodes: 0x0 continuation 0x1 text 0x2 binary 0x8 close 0x9 ping 0xA pong