subsys/bluetooth/host/att_internal.h

/* att_internal.h - Attribute protocol handling */

#include <stdint.h>
#include <stddef.h>

#include <zephyr/bluetooth/att.h>
#include <zephyr/bluetooth/conn.h>
#include <zephyr/bluetooth/l2cap.h>
#include <zephyr/kernel.h>
#include <zephyr/net_buf.h>
#include <zephyr/sys/slist.h>
#include <zephyr/sys/util.h>
#include <zephyr/sys_clock.h>

/*
 * Copyright (c) 2015-2016 Intel Corporation
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#define BT_EATT_PSM		0x27
#define BT_ATT_DEFAULT_LE_MTU	23
#define BT_ATT_TIMEOUT_SEC	30
#define BT_ATT_TIMEOUT		K_SECONDS(BT_ATT_TIMEOUT_SEC)

/* Local ATT Rx MTU
 *
 * This is the local 'Client Rx MTU'/'Server Rx MTU'. Core v5.3 Vol 3 Part F
 * 3.4.2.2 requires that they are equal.
 *
 * The local ATT Server Rx MTU is limited to BT_L2CAP_TX_MTU because the GATT
 * long attribute read protocol (Core v5.3 Vol 3 Part G 4.8.3) treats the ATT
 * MTU as a promise about the read size. This requires the server to negotiate
 * the ATT_MTU down to what it is actually able to send. This will unfortunately
 * also limit how much the client is allowed to send.
 */
#define BT_LOCAL_ATT_MTU_EATT MIN(BT_L2CAP_SDU_RX_MTU, BT_L2CAP_SDU_TX_MTU)
#define BT_LOCAL_ATT_MTU_UATT MIN(BT_L2CAP_RX_MTU, BT_L2CAP_TX_MTU)

#define BT_ATT_BUF_SIZE MAX(BT_LOCAL_ATT_MTU_UATT, BT_LOCAL_ATT_MTU_EATT)

struct bt_att_hdr {
	uint8_t  code;
} __packed;

#define BT_ATT_OP_ERROR_RSP			0x01
struct bt_att_error_rsp {
	uint8_t  request;
	uint16_t handle;
	uint8_t  error;
} __packed;

#define BT_ATT_OP_MTU_REQ			0x02
struct bt_att_exchange_mtu_req {
	uint16_t mtu;
} __packed;

#define BT_ATT_OP_MTU_RSP			0x03
struct bt_att_exchange_mtu_rsp {
	uint16_t mtu;
} __packed;

/* Find Information Request */
#define BT_ATT_OP_FIND_INFO_REQ			0x04
struct bt_att_find_info_req {
	uint16_t start_handle;
	uint16_t end_handle;
} __packed;

/* Format field values for BT_ATT_OP_FIND_INFO_RSP */
#define BT_ATT_INFO_16				0x01
#define BT_ATT_INFO_128				0x02

struct bt_att_info_16 {
	uint16_t handle;
	uint16_t uuid;
} __packed;

struct bt_att_info_128 {
	uint16_t handle;
	uint8_t  uuid[16];
} __packed;

/* Find Information Response */
#define BT_ATT_OP_FIND_INFO_RSP			0x05
struct bt_att_find_info_rsp {
	uint8_t  format;
	uint8_t  info[];
} __packed;

/* Find By Type Value Request */
#define BT_ATT_OP_FIND_TYPE_REQ			0x06
struct bt_att_find_type_req {
	uint16_t start_handle;
	uint16_t end_handle;
	uint16_t type;
	uint8_t  value[];
} __packed;

struct bt_att_handle_group {
	uint16_t start_handle;
	uint16_t end_handle;
} __packed;

/* Find By Type Value Response */
#define BT_ATT_OP_FIND_TYPE_RSP			0x07
struct bt_att_find_type_rsp {
	FLEXIBLE_ARRAY_DECLARE(struct bt_att_handle_group, list);
} __packed;

/* Read By Type Request */
#define BT_ATT_OP_READ_TYPE_REQ			0x08
struct bt_att_read_type_req {
	uint16_t start_handle;
	uint16_t end_handle;
	uint8_t  uuid[];
} __packed;

struct bt_att_data {
	uint16_t handle;
	uint8_t  value[];
} __packed;

/* Read By Type Response */
#define BT_ATT_OP_READ_TYPE_RSP			0x09
struct bt_att_read_type_rsp {
	uint8_t  len;
	struct bt_att_data data[];
} __packed;

/* Read Request */
#define BT_ATT_OP_READ_REQ			0x0a
struct bt_att_read_req {
	uint16_t handle;
} __packed;

/* Read Response */
#define BT_ATT_OP_READ_RSP			0x0b
struct bt_att_read_rsp {
	FLEXIBLE_ARRAY_DECLARE(uint8_t, value);
} __packed;

/* Read Blob Request */
#define BT_ATT_OP_READ_BLOB_REQ			0x0c
struct bt_att_read_blob_req {
	uint16_t handle;
	uint16_t offset;
} __packed;

/* Read Blob Response */
#define BT_ATT_OP_READ_BLOB_RSP			0x0d
struct bt_att_read_blob_rsp {
	FLEXIBLE_ARRAY_DECLARE(uint8_t, value);
} __packed;

/* Read Multiple Request */
#define BT_ATT_READ_MULT_MIN_LEN_REQ		0x04

#define BT_ATT_OP_READ_MULT_REQ			0x0e
struct bt_att_read_mult_req {
	FLEXIBLE_ARRAY_DECLARE(uint16_t, handles);
} __packed;

/* Read Multiple Response */
#define BT_ATT_OP_READ_MULT_RSP			0x0f
struct bt_att_read_mult_rsp {
	FLEXIBLE_ARRAY_DECLARE(uint8_t, value);
} __packed;

/* Read by Group Type Request */
#define BT_ATT_OP_READ_GROUP_REQ		0x10
struct bt_att_read_group_req {
	uint16_t start_handle;
	uint16_t end_handle;
	uint8_t  uuid[];
} __packed;

struct bt_att_group_data {
	uint16_t start_handle;
	uint16_t end_handle;
	uint8_t  value[];
} __packed;

/* Read by Group Type Response */
#define BT_ATT_OP_READ_GROUP_RSP		0x11
struct bt_att_read_group_rsp {
	uint8_t  len;
	struct bt_att_group_data data[];
} __packed;

/* Write Request */
#define BT_ATT_OP_WRITE_REQ			0x12
struct bt_att_write_req {
	uint16_t handle;
	uint8_t  value[];
} __packed;

/* Write Response */
#define BT_ATT_OP_WRITE_RSP			0x13

/* Prepare Write Request */
#define BT_ATT_OP_PREPARE_WRITE_REQ		0x16
struct bt_att_prepare_write_req {
	uint16_t handle;
	uint16_t offset;
	uint8_t  value[];
} __packed;

/* Prepare Write Respond */
#define BT_ATT_OP_PREPARE_WRITE_RSP		0x17
struct bt_att_prepare_write_rsp {
	uint16_t handle;
	uint16_t offset;
	uint8_t  value[];
} __packed;

/* Execute Write Request */
#define BT_ATT_FLAG_CANCEL			0x00
#define BT_ATT_FLAG_EXEC			0x01

#define BT_ATT_OP_EXEC_WRITE_REQ		0x18
struct bt_att_exec_write_req {
	uint8_t  flags;
} __packed;

/* Execute Write Response */
#define BT_ATT_OP_EXEC_WRITE_RSP		0x19

/* Handle Value Notification */
#define BT_ATT_OP_NOTIFY			0x1b
struct bt_att_notify {
	uint16_t handle;
	uint8_t  value[];
} __packed;

/* Handle Value Indication */
#define BT_ATT_OP_INDICATE			0x1d
struct bt_att_indicate {
	uint16_t handle;
	uint8_t  value[];
} __packed;

/* Handle Value Confirm */
#define BT_ATT_OP_CONFIRM			0x1e

struct bt_att_signature {
	uint8_t  value[12];
} __packed;

#define BT_ATT_OP_READ_MULT_VL_REQ		0x20
struct bt_att_read_mult_vl_req {
	FLEXIBLE_ARRAY_DECLARE(uint16_t, handles);
} __packed;

/* Read Multiple Response */
#define BT_ATT_OP_READ_MULT_VL_RSP		0x21
struct bt_att_read_mult_vl_rsp {
	uint16_t len;
	uint8_t  value[];
} __packed;

/* Handle Multiple Value Notification */
#define BT_ATT_OP_NOTIFY_MULT			0x23
struct bt_att_notify_mult {
	uint16_t handle;
	uint16_t len;
	uint8_t  value[];
} __packed;

/* Write Command */
#define BT_ATT_OP_WRITE_CMD			0x52
struct bt_att_write_cmd {
	uint16_t handle;
	uint8_t  value[];
} __packed;

/* Signed Write Command */
#define BT_ATT_OP_SIGNED_WRITE_CMD		0xd2
struct bt_att_signed_write_cmd {
	uint16_t handle;
	uint8_t  value[];
} __packed;

typedef void (*bt_att_func_t)(struct bt_conn *conn, int err,
			      const void *pdu, uint16_t length,
			      void *user_data);

typedef int (*bt_att_encode_t)(struct net_buf *buf, size_t len,
			       void *user_data);

/* ATT request context */
struct bt_att_req {
	sys_snode_t node;
	bt_att_func_t func;
	struct net_buf *buf;
#if defined(CONFIG_BT_SMP)
	bt_att_encode_t encode;
	uint8_t retrying : 1;
	uint8_t att_op;
	size_t len;
#endif /* CONFIG_BT_SMP */
	void *user_data;
};

void bt_att_init(void);
uint16_t bt_att_get_mtu(struct bt_conn *conn);
uint16_t bt_att_get_uatt_mtu(struct bt_conn *conn);
struct net_buf *bt_att_create_pdu(struct bt_conn *conn, uint8_t op,
				  size_t len);

/* Allocate a new request */
struct bt_att_req *bt_att_req_alloc(k_timeout_t timeout);

/* Free a request */
void bt_att_req_free(struct bt_att_req *req);

/* Send ATT PDU over a connection */
int bt_att_send(struct bt_conn *conn, struct net_buf *buf);

/* Send ATT Request over a connection */
int bt_att_req_send(struct bt_conn *conn, struct bt_att_req *req);

/* Cancel ATT request */
void bt_att_req_cancel(struct bt_conn *conn, struct bt_att_req *req);

/* Disconnect EATT channels */
int bt_eatt_disconnect(struct bt_conn *conn);

/** @brief Find a pending ATT request by its user_data pointer.
 *  @param conn The connection the request was issued on.
 *  @param user_data The pointer value to look for.
 *  @return The found request. NULL if not found.
 */
struct bt_att_req *bt_att_find_req_by_user_data(struct bt_conn *conn, const void *user_data);

/* Checks if only the fixed ATT channel is connected */
bool bt_att_fixed_chan_only(struct bt_conn *conn);

/* Clear the out of sync flag on all channels */
void bt_att_clear_out_of_sync_sent(struct bt_conn *conn);

/* Check if BT_ATT_ERR_DB_OUT_OF_SYNC has been sent on the fixed ATT channel */
bool bt_att_out_of_sync_sent_on_fixed(struct bt_conn *conn);

typedef void (*bt_gatt_complete_func_t) (struct bt_conn *conn, void *user_data);
void bt_att_set_tx_meta_data(struct net_buf *buf, bt_gatt_complete_func_t func, void *user_data,
			     enum bt_att_chan_opt chan_opt);
void bt_att_increment_tx_meta_data_attr_count(struct net_buf *buf, uint16_t attr_count);

bool bt_att_tx_meta_data_match(const struct net_buf *buf, bt_gatt_complete_func_t func,
			       const void *user_data, enum bt_att_chan_opt chan_opt);

#if defined(CONFIG_BT_EATT)
#define BT_ATT_CHAN_OPT(_params) (_params)->chan_opt
#else
#define BT_ATT_CHAN_OPT(_params) BT_ATT_CHAN_OPT_UNENHANCED_ONLY
#endif /* CONFIG_BT_EATT */

bool bt_att_chan_opt_valid(struct bt_conn *conn, enum bt_att_chan_opt chan_opt);

void bt_gatt_req_set_mtu(struct bt_att_req *req, uint16_t mtu);