ToC path:

mco_lews_is_websocket_close_frame
RT

Prototype

    int mco_lews_is_websocket_close_frame(const char *buf, mco_size_t buf_size);

Arguments

buf

Pointer to the raw incoming data buffer.

buf_size

Size (in bytes) of the buffer pointed to by buf.

Description

This function is used to detect client-initiated WebSocket shutdown requests.

The function checks whether the provided buffer contains a valid WebSocket close control frame as defined in RFC 6455.

It validates the following aspects of the frame:

Frame must be final (FIN = 1).

No reserved bits set (RSV1–RSV3 = 0).

Opcode must be 0x8 (close).

Payload length must be ≤ 125 bytes and not equal to 1 byte.

Frame must be complete (buffer size sufficient for header, mask, and payload).

If a close status code is present (payload ≥ 2 bytes), it must be a valid WebSocket close code (e.g., 1000, 1001, 1002, etc.).

Return Value

1

The buffer contains a fully valid WebSocket close frame.

0

The buffer does not contain a valid close frame (e.g., wrong opcode, invalid structure, unsupported close code, or insufficient data).

Files

Header file:

mcoewslite.h

Source file:

mcoewslite.c

Library:

mcoewslite.a