extmod/modbluetooth: Support gap_connect(None) to cancel a connection.

Allow cancellation of in-progress peripheral connections.

docs/library/bluetooth.rst

@@ -365,7 +365,12 @@ A central device can connect to peripherals that it has discovered using the obs
 
     See :meth:`gap_scan <BLE.gap_scan>` for details about address types.
 
-    On success, the ``_IRQ_PERIPHERAL_CONNECT`` event will be raised.
+    To cancel an outstanding connection attempt early, call
+    ``gap_connect(None)``.
+
+    On success, the ``_IRQ_PERIPHERAL_CONNECT`` event will be raised. If
+    cancelling a connection attempt, the ``_IRQ_PERIPHERAL_DISCONNECT`` event
+    will be raised.
 
     The device will wait up to *scan_duration_ms* to receive an advertising
     payload from the device.

extmod/btstack/modbluetooth_btstack.c

@@ -1284,6 +1284,11 @@ int mp_bluetooth_gap_peripheral_connect(uint8_t addr_type, const uint8_t *addr,
     return btstack_error_to_errno(gap_connect(btstack_addr, addr_type));
 }
 
+int mp_bluetooth_gap_peripheral_connect_cancel(void) {
+    DEBUG_printf("mp_bluetooth_gap_peripheral_connect_cancel\n");
+    return btstack_error_to_errno(gap_connect_cancel());
+}
+
 #endif // MICROPY_PY_BLUETOOTH_ENABLE_CENTRAL_MODE
 
 #if MICROPY_PY_BLUETOOTH_ENABLE_GATT_CLIENT

extmod/modbluetooth.c

@@ -630,6 +630,13 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_2(bluetooth_ble_gatts_register_services_obj, blue
 
 #if MICROPY_PY_BLUETOOTH_ENABLE_CENTRAL_MODE
 STATIC mp_obj_t bluetooth_ble_gap_connect(size_t n_args, const mp_obj_t *args) {
+    if (n_args == 2) {
+        if (args[1] == mp_const_none) {
+            int err = mp_bluetooth_gap_peripheral_connect_cancel();
+            return bluetooth_handle_errno(err);
+        }
+        mp_raise_TypeError(MP_ERROR_TEXT("invalid addr"));
+    }
     uint8_t addr_type = mp_obj_get_int(args[1]);
     mp_buffer_info_t bufinfo = {0};
     mp_get_buffer_raise(args[2], &bufinfo, MP_BUFFER_READ);
@@ -652,7 +659,7 @@ STATIC mp_obj_t bluetooth_ble_gap_connect(size_t n_args, const mp_obj_t *args) {
     int err = mp_bluetooth_gap_peripheral_connect(addr_type, bufinfo.buf, scan_duration_ms, min_conn_interval_us, max_conn_interval_us);
     return bluetooth_handle_errno(err);
 }
-STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(bluetooth_ble_gap_connect_obj, 3, 6, bluetooth_ble_gap_connect);
+STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(bluetooth_ble_gap_connect_obj, 2, 6, bluetooth_ble_gap_connect);
 
 STATIC mp_obj_t bluetooth_ble_gap_scan(size_t n_args, const mp_obj_t *args) {
     // Default is indefinite scan, with the NimBLE "background scan" interval and window.

extmod/modbluetooth.h

@@ -374,6 +374,10 @@ int mp_bluetooth_gap_peripheral_connect(uint8_t addr_type, const uint8_t *addr,
 #endif
 
 #if MICROPY_PY_BLUETOOTH_ENABLE_GATT_CLIENT
+
+// Cancel in-progress connection to a peripheral.
+int mp_bluetooth_gap_peripheral_connect_cancel(void);
+
 // Find all primary services on the connected peripheral.
 int mp_bluetooth_gattc_discover_primary_services(uint16_t conn_handle, const mp_obj_bluetooth_uuid_t *uuid);
 

extmod/nimble/modbluetooth_nimble.c

@@ -1236,6 +1236,15 @@ int mp_bluetooth_gap_peripheral_connect(uint8_t addr_type, const uint8_t *addr,
     return ble_hs_err_to_errno(err);
 }
 
+int mp_bluetooth_gap_peripheral_connect_cancel(void) {
+    DEBUG_printf("mp_bluetooth_gap_peripheral_connect_cancel\n");
+    if (!mp_bluetooth_is_active()) {
+        return ERRNO_BLUETOOTH_NOT_ACTIVE;
+    }
+    int err = ble_gap_conn_cancel();
+    return ble_hs_err_to_errno(err);
+}
+
 STATIC int ble_gattc_service_cb(uint16_t conn_handle, const struct ble_gatt_error *error, const struct ble_gatt_svc *service, void *arg) {
     DEBUG_printf("ble_gattc_service_cb: conn_handle=%d status=%d start_handle=%d\n", conn_handle, error->status, service ? service->start_handle : -1);
     if (!mp_bluetooth_is_active()) {