Insights into States of L2CAP Channel

[tkhang1999]

Hi,

We are currently working on the formal verification of the state machine in L2CAP. As part of this effort, we have been studying the Bluetooth Core Specification 5.4, particularly Vol 3, Part A, Section 6, which specifies the L2CAP state machine.

While looking over your implementation of L2CAP, we noticed the defined states for the L2CAP channel. We are curious about the documentation/references/specifications you used to derive the comments for these states, specifically the comment /** Channel in config state, BR/EDR specific */ regarding BT_L2CAP_CONFIG. As we are unable to locate such information in the Bluetooth specification, could you share insights or resources that guided your implementation?

...
typedef enum bt_l2cap_chan_state {
	/** Channel disconnected */
	BT_L2CAP_DISCONNECTED,
	/** Channel in connecting state */
	BT_L2CAP_CONNECTING,
	/** Channel in config state, BR/EDR specific */
	BT_L2CAP_CONFIG,
	/** Channel ready for upper layer traffic on it */
	BT_L2CAP_CONNECTED,
	/** Channel in disconnecting state */
	BT_L2CAP_DISCONNECTING,

} __packed bt_l2cap_chan_state_t;
...

Ref: https://github.com/zephyrproject-rtos/zephyr/blob/main/include/zephyr/bluetooth/l2cap.h#L144-L156