ATT Database Engine API
src/ble/att_db.h
// map ATT ERROR CODES on to att_read_callback length
#define ATT_READ_ERROR_CODE_OFFSET 0xfe00u
// custom BTstack ATT Response Pending for att_read_callback
#define ATT_READ_RESPONSE_PENDING 0xffffu
// internally used to signal write response pending
// To ask ATT Server to defer the write response, you can return ATT_ERROR_WRITE_RESPONSE_PENDING in your att_write_callback
#define ATT_INTERNAL_WRITE_RESPONSE_PENDING 0xfffeu
/**
* @brief ATT Client Read Callback for Dynamic Data
* - if buffer == NULL, don't copy data, just return size of value
* - if buffer != NULL, copy data and return number bytes copied
*
* If ENABLE_ATT_DELAYED_READ_RESPONSE is defined, you may return ATT_READ_RESPONSE_PENDING if data isn't available yet
* and call att_server_response_ready to re-trigger the callback.
*
* @param con_handle of hci le connection
* @param attribute_handle to be read
* @param offset defines start of attribute value
* @param buffer
* @param buffer_size
* @return size of value if buffer is NULL, otherwise number of bytes copied
*/
typedef uint16_t (*att_read_callback_t)(hci_con_handle_t con_handle, uint16_t attribute_handle, uint16_t offset, uint8_t * buffer, uint16_t buffer_size);
/**
* @brief ATT Client Write Callback for Dynamic Data
* Each Prepared Write Request triggers a callback with transaction mode ATT_TRANSACTION_MODE_ACTIVE.
* On Execute Write, the callback will be called with ATT_TRANSACTION_MODE_VALIDATE and allows to validate all queued writes and return an application error.
* If none of the registered callbacks return an error for ATT_TRANSACTION_MODE_VALIDATE and the callback will be called with ATT_TRANSACTION_MODE_EXECUTE.
* Otherwise, all callbacks will be called with ATT_TRANSACTION_MODE_CANCEL.
*
* If the additional validation step is not needed, just return 0 for all callbacks with transaction mode ATT_TRANSACTION_MODE_VALIDATE.
*
* If ENABLE_ATT_DELAYED_READ_RESPONSE is defined, you may return ATT_ERROR_WRITE_RESPONSE_PENDING if data isn't available yet
* and call att_server_response_ready to re-trigger the callback.
*
* @param con_handle of hci le connection
* @param attribute_handle to be written
* @param transaction - ATT_TRANSACTION_MODE_NONE for regular writes. For prepared writes: ATT_TRANSACTION_MODE_ACTIVE, ATT_TRANSACTION_MODE_VALIDATE, ATT_TRANSACTION_MODE_EXECUTE, ATT_TRANSACTION_MODE_CANCEL
* @param offset into the value - used for queued writes and long attributes
* @param buffer
* @param buffer_size
* @param signature used for signed write commmands
* @return 0 if write was ok, ATT_ERROR_PREPARE_QUEUE_FULL if no space in queue, ATT_ERROR_INVALID_OFFSET if offset is larger than max buffer
*/
typedef int (*att_write_callback_t)(hci_con_handle_t con_handle, uint16_t attribute_handle, uint16_t transaction_mode, uint16_t offset, uint8_t *buffer, uint16_t buffer_size);
// Read & Write Callbacks for handle range
typedef struct att_service_handler {
btstack_linked_item_t * item;
att_read_callback_t read_callback;
att_write_callback_t write_callback;
btstack_packet_handler_t packet_handler;
uint16_t start_handle;
uint16_t end_handle;
uint8_t flags;
} att_service_handler_t;
// MARK: ATT Operations
/**
* @brief setup ATT database
* @param db
*/
void att_set_db(uint8_t const * db);
/*
* @brief set callback for read of dynamic attributes
* @param callback
*/
void att_set_read_callback(att_read_callback_t callback);
/**
* @brief set callback for write of dynamic attributes
* @param callback
*/
void att_set_write_callback(att_write_callback_t callback);
/**
* @brief debug helper, dump ATT database to stdout using log_info
*/
void att_dump_attributes(void);
/**
* @brief process ATT request against database and put response into response buffer
* @param att_connection used for mtu and security properties
* @param request_buffer, request_len: ATT request from clinet
* @param response_buffer for result
* @return len of data in response buffer. 0 = no response,
* ATT_READ_RESPONSE_PENDING if it was returned at least once for dynamic data (requires ENABLE_ATT_DELAYED_READ_RESPONSE)
*/
uint16_t att_handle_request(att_connection_t * att_connection,
uint8_t * request_buffer,
uint16_t request_len,
uint8_t * response_buffer);
/**
* @brief setup value notification in response buffer for a given handle and value
* @param att_connection
* @param attribute_handle
* @param value
* @param value_len
* @param response_buffer for notification
*/
uint16_t att_prepare_handle_value_notification(att_connection_t * att_connection,
uint16_t attribute_handle,
const uint8_t *value,
uint16_t value_len,
uint8_t * response_buffer);
/**
* @brief setup value notification in response buffer for multiple handles and values
* @param att_connection
* @param attribute_handle
* @param value
* @param value_len
* @param response_buffer for notification
*/
uint16_t att_prepare_handle_value_multiple_notification(att_connection_t * att_connection,
uint8_t num_attributes,
const uint16_t * attribute_handles,
const uint8_t ** values_data,
const uint16_t * values_len,
uint8_t * response_buffer);
/**
* @brief setup value indication in response buffer for a given handle and value
* @param att_connection
* @param attribute_handle
* @param value
* @param value_len
* @param response_buffer for indication
*/
uint16_t att_prepare_handle_value_indication(att_connection_t * att_connection,
uint16_t attribute_handle,
const uint8_t *value,
uint16_t value_len,
uint8_t * response_buffer);
/**
* @brief transcation queue of prepared writes, e.g., after disconnect
* @return att_connection
*/
void att_clear_transaction_queue(att_connection_t * att_connection);
// att_read_callback helpers for a various data types
/**
* @brief Handle read of blob like data for att_read_callback
* @param blob of data
* @param blob_size of blob
* @param offset from att_read_callback
* @param buffer from att_read_callback
* @param buffer_size from att_read_callback
* @return value size for buffer == 0 and num bytes copied otherwise
*/
uint16_t att_read_callback_handle_blob(const uint8_t * blob, uint16_t blob_size, uint16_t offset, uint8_t * buffer, uint16_t buffer_size);
/**
* @brief Handle read of little endian unsigned 32 bit value for att_read_callback
* @param value
* @param offset from att_read_callback
* @param buffer from att_read_callback
* @param buffer_size from att_read_callback
* @return value size for buffer == 0 and num bytes copied otherwise
*/
uint16_t att_read_callback_handle_little_endian_32(uint32_t value, uint16_t offset, uint8_t * buffer, uint16_t buffer_size);
/**
* @brief Handle read of little endian unsigned 16 bit value for att_read_callback
* @param value
* @param offset from att_read_callback
* @param buffer from att_read_callback
* @param buffer_size from att_read_callback
* @return value size for buffer == 0 and num bytes copied otherwise
*/
uint16_t att_read_callback_handle_little_endian_16(uint16_t value, uint16_t offset, uint8_t * buffer, uint16_t buffer_size);
/**
* @brief Handle read of single byte for att_read_callback
* @param blob of data
* @param blob_size of blob
* @param offset from att_read_callback
* @param buffer from att_read_callback
* @param buffer_size from att_read_callback
* @return value size for buffer == 0 and num bytes copied otherwise
*/
uint16_t att_read_callback_handle_byte(uint8_t value, uint16_t offset, uint8_t * buffer, uint16_t buffer_size);
// experimental client API
/**
* @brief Get UUID for handle
* @param attribute_handle
* @return 0 if not found
*/
uint16_t att_uuid_for_handle(uint16_t attribute_handle);
/**
* @brief Get const value for handle
* @param attribute_handle
* @param out_value_len output variable that hold value len
* @return value
*/
const uint8_t * gatt_server_get_const_value_for_handle(uint16_t attribute_handle, uint16_t * out_value_len);
// experimental GATT Server API
/**
* @brief Get handle range for primary service.
* @param uuid16
* @param start_handle
* @param end_handle
* @return false if not found
*/
bool gatt_server_get_handle_range_for_service_with_uuid16(uint16_t uuid16, uint16_t * start_handle, uint16_t * end_handle);
/**
* @brief Get handle range for included service.
* @param start_handle
* @param end_handle
* @param uuid16
* @param out_included_service_handle
* @param out_included_service_start_handle
* @param out_included_service_end_handle
* @return false if not found
*/
bool gatt_server_get_included_service_with_uuid16(uint16_t start_handle, uint16_t end_handle, uint16_t uuid16,
uint16_t * out_included_service_handle, uint16_t * out_included_service_start_handle, uint16_t * out_included_service_end_handle);
/**
* @brief Get value handle for characteristic.
* @param start_handle
* @param end_handle
* @param uuid16
* @return 0 if not found
*/
uint16_t gatt_server_get_value_handle_for_characteristic_with_uuid16(uint16_t start_handle, uint16_t end_handle, uint16_t uuid16);
/**
* @brief Get descriptor handle for characteristic.
* @param start_handle
* @param end_handle
* @param characteristic_uuid16
* @param descriptor_uuid16
* @return 0 if not found
*/
uint16_t gatt_server_get_descriptor_handle_for_characteristic_with_uuid16(uint16_t start_handle, uint16_t end_handle, uint16_t characteristic_uuid16, uint16_t descriptor_uuid16);
/**
* @brief Get client configuration handle for characteristic.
* @param start_handle
* @param end_handle
* @param characteristic_uuid16
* @return 0 if not found
*/
uint16_t gatt_server_get_client_configuration_handle_for_characteristic_with_uuid16(uint16_t start_handle, uint16_t end_handle, uint16_t characteristic_uuid16);
/**
* @brief Get server configuration handle for characteristic.
* @param start_handle
* @param end_handle
* @param characteristic_uuid16
* @param descriptor_uuid16
* @return 0 if not found
*/
uint16_t gatt_server_get_server_configuration_handle_for_characteristic_with_uuid16(uint16_t start_handle, uint16_t end_handle, uint16_t characteristic_uuid16);
/**
* @brief Get handle range for primary service.
* @param uuid128
* @param start_handle
* @param end_handle
* @return false if not found
*/
bool gatt_server_get_handle_range_for_service_with_uuid128(const uint8_t * uuid128, uint16_t * start_handle, uint16_t * end_handle);
/**
* @brief Get value handle.
* @param start_handle
* @param end_handle
* @param uuid128
* @return 0 if not found
*/
uint16_t gatt_server_get_value_handle_for_characteristic_with_uuid128(uint16_t start_handle, uint16_t end_handle, const uint8_t * uuid128);
/**
* @brief Get client configuration handle.
* @param start_handle
* @param end_handle
* @param uuid128
* @return 0 if not found
*/
uint16_t gatt_server_get_client_configuration_handle_for_characteristic_with_uuid128(uint16_t start_handle, uint16_t end_handle, const uint8_t * uuid128);