websocket.h File Reference

Layer 6 (Presentation) – WebSocket frame parser and connection pool. More...

#include "protocore_config.h"

Go to the source code of this file.

Detailed Description

Layer 6 (Presentation) – WebSocket frame parser and connection pool.

Implements RFC 6455 framing with a fixed-size payload buffer per slot. Connections are tracked in ws_pool[MAX_WS_CONNS]; each entry maps to one TCP slot in conn_pool[] via slot_id.

Frame format (client to server)

 0               1               2               3
 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-------+-+-------------+-------------------------------+
|F|R|R|R| opcode|M| payload len |    extended payload length    |
|I|S|S|S|  (4)  |A|     (7)    |             (16/64)           |
|N|V|V|V|       |S|             +-------------------------------+
| |1|2|3|       |K|             |                               |
+-+-+-+-+-------+-+-------------+ - - - - - - - - - - - - - - -+
|     extended payload length continued, if payload len == 127  |
+ - - - - - - - - - - - - - - -+-------------------------------+
|                               | masking key, if MASK set      |
+-------------------------------+-------------------------------+
| masking key (continued)       |          payload data         |
+-------------------------------- - - - - - - - - - - - - - - -+
:                     payload data continued                    :
+---------------------------------------------------------------+

State machine

WS_HEADER1       -- read FIN + opcode byte
WS_HEADER2       -- read MASK + 7-bit payload length
WS_LEN16_HI      -- read extended 16-bit length high byte
WS_LEN16_LO      -- read extended 16-bit length low byte
WS_LEN64         -- consume 8-byte 64-bit length (reject; too large)
WS_MASK0..3      -- read 4-byte masking key
WS_PAYLOAD       -- accumulate payload bytes (unmasked)
WS_FRAME_READY   -- complete frame waiting for dispatch
WS_CLOSED        -- connection closed; slot may be recycled
WS_ERROR         -- protocol error; close frame sent

Limitations

• A reassembled message must fit in WS_FRAME_SIZE bytes; larger closes 1009.
• RSV bits must be zero (no extensions supported).

Fragmentation (RFC 6455 §5.4) Fragmented data messages are reassembled into buf across continuation frames; the message is delivered only when the FIN frame arrives. Control frames (ping/pong/close) may be interleaved between fragments and are handled immediately without disturbing the partial message.

Author

Douglas Quigg (dstroy0)

Date

2026

Definition in file websocket.h.