btif/src/btif_uid.cc

/*
 * Copyright 2016 The Android Open Source Project
 *
 * 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.
 */

/*******************************************************************************
 *
 *  Filename:      btif_uid.cc
 *
 *  Description:   Contains data structures and functions for keeping track of
 *                 socket usage per app UID.
 *
 ******************************************************************************/
#include <mutex>

#include "bt_common.h"
#include "btif_uid.h"

static std::mutex set_lock;

typedef struct uid_set_node_t {
  struct uid_set_node_t* next;
  bt_uid_traffic_t data;
} uid_set_node_t;

typedef struct uid_set_t {
  uid_set_node_t* head;
} uid_set_t;

uid_set_t* uid_set_create(void) {
  uid_set_t* set = (uid_set_t*)osi_calloc(sizeof(uid_set_t));
  return set;
}

void uid_set_destroy(uid_set_t* set) {
  std::unique_lock<std::mutex> guard(set_lock);
  uid_set_node_t* node = set->head;
  while (node) {
    uid_set_node_t* temp = node;
    node = node->next;
    osi_free(temp);
  }
  set->head = NULL;
  osi_free(set);
}

// Lock in uid_set_t must be held.
static uid_set_node_t* uid_set_find_or_create_node(uid_set_t* set,
                                                   int32_t app_uid) {
  uid_set_node_t* node = set->head;
  while (node && node->data.app_uid != app_uid) {
    node = node->next;
  }

  if (!node) {
    node = (uid_set_node_t*)osi_calloc(sizeof(uid_set_node_t));
    node->data.app_uid = app_uid;
    node->next = set->head;
    set->head = node;
  }
  return node;
}

void uid_set_add_tx(uid_set_t* set, int32_t app_uid, uint64_t bytes) {
  if (app_uid == -1 || bytes == 0) return;

  std::unique_lock<std::mutex> guard(set_lock);
  uid_set_node_t* node = uid_set_find_or_create_node(set, app_uid);
  node->data.tx_bytes += bytes;
}

void uid_set_add_rx(uid_set_t* set, int32_t app_uid, uint64_t bytes) {
  if (app_uid == -1 || bytes == 0) return;

  std::unique_lock<std::mutex> guard(set_lock);
  uid_set_node_t* node = uid_set_find_or_create_node(set, app_uid);
  node->data.rx_bytes += bytes;
}

bt_uid_traffic_t* uid_set_read_and_clear(uid_set_t* set) {
  std::unique_lock<std::mutex> guard(set_lock);

  // Find the length
  size_t len = 0;
  uid_set_node_t* node = set->head;
  while (node) {
    len++;
    node = node->next;
  }

  // Allocate an array of elements + 1, to signify the end with app_uid set to
  // -1.
  bt_uid_traffic_t* result =
      (bt_uid_traffic_t*)osi_calloc(sizeof(bt_uid_traffic_t) * (len + 1));

  bt_uid_traffic_t* data = result;
  node = set->head;
  while (node) {
    // Copy the data.
    *data = node->data;
    data++;

    // Clear the counters.
    node->data.rx_bytes = 0;
    node->data.tx_bytes = 0;
    node = node->next;
  }

  // Mark the last entry
  data->app_uid = -1;

  return result;
}