extmod/modbluetooth: Add gap_unpair command.

This function deletes the pairing details from the DB on both the application and the radio, so can be used to free up IRK slots on the radio.

Author: pi-anl

docs/library/bluetooth.rst

@@ -733,6 +733,11 @@ Pairing and bonding
 
     On successful pairing, the ``_IRQ_ENCRYPTION_UPDATE`` event will be raised.
 
+.. method:: BLE.gap_unpair(key, /)
+
+    Removes pairing details from the bond database, where ``key`` is the entry key 
+    as provided in _IRQ_GET_SECRET/_IRQ_SET_SECRET events.
+
 .. method:: BLE.gap_passkey(conn_handle, action, passkey, /)
 
     Respond to a ``_IRQ_PASSKEY_ACTION`` event for the specified *conn_handle*

extmod/btstack/modbluetooth_btstack.c

@@ -1262,6 +1262,27 @@ int mp_bluetooth_gap_pair(uint16_t conn_handle) {
     return 0;
 }
 
+int mp_bluetooth_gap_unpair(uint8_t *key, size_t key_len) {
+    DEBUG_printf("mp_bluetooth_gap_unpair\n");
+    if (BD_ADDR_LEN != key_len) {
+        mp_raise_ValueError(MP_ERROR_TEXT("Incorrect key length"));
+    }
+
+    int addr_type;
+    bd_addr_t addr;
+    sm_key_t irk;
+    for (int i = 0; i < MAX_NR_LE_DEVICE_DB_ENTRIES; i++) {
+        le_device_db_info(i, &addr_type, addr, irk);
+        if (addr_type != BD_ADDR_TYPE_UNKNOWN) {
+            if (0 == memcmp(key, addr, BD_ADDR_LEN)) {
+                le_device_db_remove(i);
+                return 0;
+            }
+        }
+    }
+    return MP_ENOENT;
+}
+
 int mp_bluetooth_gap_passkey(uint16_t conn_handle, uint8_t action, mp_int_t passkey) {
     DEBUG_printf("mp_bluetooth_gap_passkey: conn_handle=%d action=%d passkey=%d\n", conn_handle, action, (int)passkey);
     return MP_EOPNOTSUPP;

extmod/modbluetooth.c

@@ -716,6 +716,21 @@ static mp_obj_t bluetooth_ble_gap_pair(mp_obj_t self_in, mp_obj_t conn_handle_in
 }
 static MP_DEFINE_CONST_FUN_OBJ_2(bluetooth_ble_gap_pair_obj, bluetooth_ble_gap_pair);
 
+static mp_obj_t bluetooth_ble_gap_unpair(mp_obj_t self_in, mp_obj_t key_buff) {
+    (void)self_in;
+
+    uint8_t *key = NULL;
+    size_t key_len = 0;
+
+    mp_buffer_info_t key_bufinfo = {0};
+    mp_get_buffer_raise(key_buff, &key_bufinfo, MP_BUFFER_READ);
+    key = key_bufinfo.buf;
+    key_len = key_bufinfo.len;
+
+    return bluetooth_handle_errno(mp_bluetooth_gap_unpair(key, key_len));
+}
+static MP_DEFINE_CONST_FUN_OBJ_2(bluetooth_ble_gap_unpair_obj, bluetooth_ble_gap_unpair);
+
 static mp_obj_t bluetooth_ble_gap_passkey(size_t n_args, const mp_obj_t *args) {
     uint16_t conn_handle = mp_obj_get_int(args[1]);
     uint8_t action = mp_obj_get_int(args[2]);
@@ -944,6 +959,7 @@ static const mp_rom_map_elem_t bluetooth_ble_locals_dict_table[] = {
     { MP_ROM_QSTR(MP_QSTR_gap_disconnect), MP_ROM_PTR(&bluetooth_ble_gap_disconnect_obj) },
     #if MICROPY_PY_BLUETOOTH_ENABLE_PAIRING_BONDING
     { MP_ROM_QSTR(MP_QSTR_gap_pair), MP_ROM_PTR(&bluetooth_ble_gap_pair_obj) },
+    { MP_ROM_QSTR(MP_QSTR_gap_unpair), MP_ROM_PTR(&bluetooth_ble_gap_unpair_obj) },
     { MP_ROM_QSTR(MP_QSTR_gap_passkey), MP_ROM_PTR(&bluetooth_ble_gap_passkey_obj) },
     #endif
     // GATT Server

extmod/modbluetooth.h

@@ -358,6 +358,9 @@ int mp_bluetooth_set_preferred_mtu(uint16_t mtu);
 // Initiate pairing on the specified connection.
 int mp_bluetooth_gap_pair(uint16_t conn_handle);
 
+// Remove a specific pairing key from the radio.
+int mp_bluetooth_gap_unpair(uint8_t *key, size_t key_len);
+
 // Respond to a pairing request.
 int mp_bluetooth_gap_passkey(uint16_t conn_handle, uint8_t action, mp_int_t passkey);
 #endif // MICROPY_PY_BLUETOOTH_ENABLE_PAIRING_BONDING

extmod/nimble/modbluetooth_nimble.c

@@ -1100,6 +1100,15 @@ int mp_bluetooth_gap_pair(uint16_t conn_handle) {
     return ble_hs_err_to_errno(ble_gap_security_initiate(conn_handle));
 }
 
+int mp_bluetooth_gap_unpair(uint8_t *key, size_t key_len) {
+    if (sizeof(ble_addr_t) != key_len) {
+        mp_raise_ValueError(MP_ERROR_TEXT("Incorrect key length"));
+    }
+
+    DEBUG_printf("mp_bluetooth_gap_unpair: specific\n");
+    return ble_hs_err_to_errno(ble_gap_unpair((ble_addr_t *)key));
+}
+
 int mp_bluetooth_gap_passkey(uint16_t conn_handle, uint8_t action, mp_int_t passkey) {
     struct ble_sm_io io = {0};