Import of the watch repository from Pebble

src/fw/applib/bluetooth/ble_client.c

@@ -0,0 +1,305 @@
+/*
+ * Copyright 2024 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define FILE_LOG_COLOR LOG_COLOR_BLUE
+
+#include "ble_client.h"
+
+#include "ble_app_support.h"
+
+#include "applib/applib_malloc.auto.h"
+#include "process_state/app_state/app_state.h"
+#include "syscall/syscall.h"
+#include "syscall/syscall_internal.h"
+#include "system/logging.h"
+#include "system/passert.h"
+#include "util/math.h"
+
+#include <stdint.h>
+
+// TODO:
+// - device name
+// - connection speed (?)
+// - app_info.json
+// - airplane mode service / BT HW state
+
+// - API to detect that accessory is currently already connected to the phone?
+//     - How to identify? iOS SDK does not expose addresses. Use DIS info? Fall
+//       back to device name?
+
+static void prv_handle_services_added(
+    BLEClientServiceChangeHandler handler, BTDeviceInternal device, BTErrno status) {
+  BLEService services[BLE_GATT_MAX_SERVICES_CHANGED];
+
+  uint8_t num_services = sys_ble_client_copy_services(device, services,
+                                                      BLE_GATT_MAX_SERVICES_CHANGED);
+
+  if (num_services != 0) {
+    handler(device.opaque, BLEClientServicesAdded, services, num_services, status);
+  }
+}
+
+// TODO (PBL-22086): We should really make this easier to do ...
+// We can't directly dereference the service discovery info pointer from third
+// party apps because it was malloc'ed from the kernel heap. Instead copy the
+// info that is used onto a variable which has been allocated from the stack.
+DEFINE_SYSCALL(void, sys_get_service_discovery_info, const PebbleBLEGATTClientServiceEvent *e,
+               PebbleBLEGATTClientServiceEventInfo *info) {
+  if (PRIVILEGE_WAS_ELEVATED) {
+    // Note: if we start storing services, we will need to update the size
+    syscall_assert_userspace_buffer(info, sizeof(*info));
+  }
+
+  *info = (PebbleBLEGATTClientServiceEventInfo) {
+    .type = e->info->type,
+    .device = e->info->device,
+    .status = e->info->status
+  };
+}
+
+static void prv_handle_service_change(const PebbleBLEGATTClientEvent *e) {
+  BLEAppState *ble_app_state = app_state_get_ble_app_state();
+  const BLEClientServiceChangeHandler handler =
+                                     ble_app_state->gatt_service_change_handler;
+  if (!handler) {
+    return;
+  }
+
+  PebbleBLEGATTClientServiceEventInfo info;
+  sys_get_service_discovery_info((const PebbleBLEGATTClientServiceEvent *)e, &info);
+
+  switch (info.type) {
+    case PebbleServicesAdded:
+      prv_handle_services_added(handler, info.device, info.status);
+      break;
+    case PebbleServicesRemoved:
+      // TODO (PBL-22087): This is suboptimal. Before we release the BLE API, we should
+      // either communicate to the App all the handles which have changed or
+      // allow the getters for removed services to still work for the duration
+      // of the callback. For now just force a full handle flush and then resync the app
+      handler(info.device.opaque, BLEClientServicesInvalidateAll, NULL, 0, info.status);
+      prv_handle_services_added(handler, info.device, info.status);
+      break;
+    case PebbleServicesInvalidateAll:
+      handler(info.device.opaque, BLEClientServicesInvalidateAll, NULL, 0, info.status);
+      break;
+    default:
+      WTF;
+  }
+}
+
+typedef void (*GenericReadHandler)(BLECharacteristic characteristic,
+                                   const uint8_t *value,
+                                   size_t value_length,
+                                   uint16_t value_offset,
+                                   BLEGATTError error);
+
+static void prv_consume_read_response(const PebbleBLEGATTClientEvent *e,
+                                      GenericReadHandler handler) {
+  uint8_t *value = NULL;
+  uint16_t value_length = e->value_length;
+  const uintptr_t object_ref = e->object_ref;
+  BLEGATTError gatt_error = e->gatt_error;
+
+  // Read Responses / Notifications with 0 length data must not be attempted to be consumed
+  if (value_length) {
+    value = (uint8_t *) applib_malloc(value_length);
+    if (!value) {
+      gatt_error = BLEGATTErrorLocalInsufficientResources;
+      value_length = 0;
+    }
+    // If there is a read response, we *must* consume it,
+    // otherwise the events and associated awaiting responses will
+    // get out of sync with each other.
+    sys_ble_client_consume_read(object_ref, value, &value_length);
+  }
+
+  if (handler) {
+    handler(object_ref, value, value_length, 0 /* value_offset (future proofing) */, gatt_error);
+  }
+  applib_free(value);
+}
+
+static void prv_consume_notifications(const PebbleBLEGATTClientEvent *e,
+                                      GenericReadHandler handler) {
+  uint8_t *value = NULL;
+  BLEGATTError gatt_error = e->gatt_error;
+
+  uint16_t heap_buffer_size = 0;
+  uint16_t value_length = 0;
+  bool has_more = sys_ble_client_get_notification_value_length(&value_length);
+  while (has_more) {
+    if (heap_buffer_size < value_length) {
+      const uint16_t new_heap_buffer_size = MIN(value_length, 64 /* arbitrary min size.. */);
+      applib_free(value);
+      value = (uint8_t *) applib_malloc(new_heap_buffer_size);
+      heap_buffer_size = value ? new_heap_buffer_size : 0;
+    }
+    if (!value) {
+      gatt_error = BLEGATTErrorLocalInsufficientResources;
+      value_length = 0;
+    }
+    uintptr_t object_ref;
+    // Consume, even if we didn't have enough memory, this will eat the notification and free up
+    // the space in the buffer.
+    const uint16_t next_value_length = sys_ble_client_consume_notification(&object_ref,
+                                                                           value, &value_length,
+                                                                           &has_more);
+    if (handler) {
+      handler(object_ref, value, value_length, 0 /* value_offset (future proofing) */, gatt_error);
+    }
+
+    value_length = next_value_length;
+  }
+
+  applib_free(value);
+}
+
+static void prv_handle_notifications(const PebbleBLEGATTClientEvent *e) {
+  BLEAppState *ble_app_state = app_state_get_ble_app_state();
+  prv_consume_notifications(e, ble_app_state->gatt_characteristic_read_handler);
+}
+
+static void prv_handle_characteristic_read(const PebbleBLEGATTClientEvent *e) {
+  BLEAppState *ble_app_state = app_state_get_ble_app_state();
+  prv_consume_read_response(e, ble_app_state->gatt_characteristic_read_handler);
+}
+
+static void prv_handle_characteristic_write(const PebbleBLEGATTClientEvent *e) {
+  BLEAppState *ble_app_state = app_state_get_ble_app_state();
+  const BLEClientWriteHandler handler = ble_app_state->gatt_characteristic_write_handler;
+  if (handler) {
+    handler(e->object_ref, e->gatt_error);
+  }
+}
+
+static void prv_handle_characteristic_subscribe(const PebbleBLEGATTClientEvent *e) {
+  PBL_LOG(LOG_LEVEL_DEBUG, "TODO: GATT Client Event, subtype=%u", e->subtype);
+}
+
+static void prv_handle_descriptor_read(const PebbleBLEGATTClientEvent *e) {
+  BLEAppState *ble_app_state = app_state_get_ble_app_state();
+  prv_consume_read_response(e, ble_app_state->gatt_descriptor_read_handler);
+}
+
+static void prv_handle_descriptor_write(const PebbleBLEGATTClientEvent *e) {
+  BLEAppState *ble_app_state = app_state_get_ble_app_state();
+  const BLEClientWriteDescriptorHandler handler = ble_app_state->gatt_descriptor_write_handler;
+  if (handler) {
+    handler(e->object_ref, e->gatt_error);
+  }
+}
+
+static void prv_handle_buffer_empty(const PebbleBLEGATTClientEvent *e) {
+  // TODO
+}
+
+typedef void(*PrvHandler)(const PebbleBLEGATTClientEvent *);
+
+static PrvHandler prv_handler_for_subtype(
+                                   PebbleBLEGATTClientEventType event_subtype) {
+  if (event_subtype >= PebbleBLEGATTClientEventTypeNum) {
+    WTF;
+  }
+  // MT: This is a bit smaller in code size than a switch():
+  static const PrvHandler handler[] = {
+    [PebbleBLEGATTClientEventTypeServiceChange] = prv_handle_service_change,
+    [PebbleBLEGATTClientEventTypeCharacteristicRead] = prv_handle_characteristic_read,
+    [PebbleBLEGATTClientEventTypeNotification] = prv_handle_notifications,
+    [PebbleBLEGATTClientEventTypeCharacteristicWrite] = prv_handle_characteristic_write,
+    [PebbleBLEGATTClientEventTypeCharacteristicSubscribe] = prv_handle_characteristic_subscribe,
+    [PebbleBLEGATTClientEventTypeDescriptorRead] = prv_handle_descriptor_read,
+    [PebbleBLEGATTClientEventTypeDescriptorWrite] = prv_handle_descriptor_write,
+    [PebbleBLEGATTClientEventTypeBufferEmpty] = prv_handle_buffer_empty,
+  };
+  return handler[event_subtype];
+}
+
+// Exported for ble_app_support.c
+void ble_client_handle_event(PebbleEvent *e) {
+  const PebbleBLEGATTClientEvent *gatt_event = &e->bluetooth.le.gatt_client;
+  prv_handler_for_subtype(gatt_event->subtype)(gatt_event);
+}
+
+static BTErrno prv_set_handler(void *new_handler, off_t struct_offset_bytes) {
+  BLEAppState *ble_app_state = app_state_get_ble_app_state();
+  typedef void (*BLEGenericHandler)(void);
+  BLEGenericHandler *handler_storage =
+       (BLEGenericHandler *)(((uint8_t *) ble_app_state) + struct_offset_bytes);
+
+  const bool had_previous_handler = (*handler_storage == NULL);
+  *handler_storage = (BLEGenericHandler) new_handler;
+
+  if (had_previous_handler) {
+    if (new_handler) {
+      if (ble_app_state->gatt_client_num_handlers++ == 0) {
+        // First GATT handler to be registered.
+        // Subscribe to GATT Client event service:
+        event_service_client_subscribe(&ble_app_state->gatt_client_service_info);
+      }
+    }
+  } else {
+    if (!new_handler) {
+      if (--ble_app_state->gatt_client_num_handlers == 0) {
+        // Last GATT handler to be de-registered.
+        // Unsubscribe from GATT Client event service:
+        event_service_client_unsubscribe(&ble_app_state->gatt_client_service_info);
+      }
+    }
+  }
+  return BTErrnoOK;
+}
+
+BTErrno ble_client_set_service_filter(const Uuid service_uuids[],
+                                      uint8_t num_uuids) {
+  // TODO
+  return 0;
+}
+
+BTErrno ble_client_set_service_change_handler(BLEClientServiceChangeHandler handler) {
+  const off_t offset = offsetof(BLEAppState, gatt_service_change_handler);
+  return prv_set_handler(handler, offset);
+}
+
+BTErrno ble_client_set_read_handler(BLEClientReadHandler handler) {
+  const off_t offset = offsetof(BLEAppState, gatt_characteristic_read_handler);
+  return prv_set_handler(handler, offset);
+}
+
+BTErrno ble_client_set_write_response_handler(BLEClientWriteHandler handler) {
+  const off_t offset = offsetof(BLEAppState, gatt_characteristic_write_handler);
+  return prv_set_handler(handler, offset);
+}
+
+BTErrno ble_client_set_subscribe_handler(BLEClientSubscribeHandler handler) {
+  const off_t offset = offsetof(BLEAppState, gatt_characteristic_subscribe_handler);
+  return prv_set_handler(handler, offset);
+}
+
+BTErrno ble_client_set_buffer_empty_handler(BLEClientBufferEmptyHandler empty_handler) {
+  // TODO
+  return BTErrnoOther;
+}
+
+BTErrno ble_client_set_descriptor_write_handler(BLEClientWriteDescriptorHandler handler) {
+  const off_t offset = offsetof(BLEAppState, gatt_descriptor_write_handler);
+  return prv_set_handler(handler, offset);
+}
+
+BTErrno ble_client_set_descriptor_read_handler(BLEClientReadDescriptorHandler handler) {
+  const off_t offset = offsetof(BLEAppState, gatt_descriptor_read_handler);
+  return prv_set_handler(handler, offset);
+}