content: /*
   * Copyright (C) 2019 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.
   */
  
  package android.net.util;
  
  import android.annotation.NonNull;
  import android.content.Context;
  import android.content.res.Resources;
  import android.net.NetworkCapabilities;
  import android.text.TextUtils;
  import android.util.AndroidRuntimeException;
  
  import com.android.internal.R;
  
  /**
   * Collection of utilities for socket keepalive offload.
   *
   * @hide
   */
  public final class KeepaliveUtils {
  
      public static final String TAG = "KeepaliveUtils";
  
      public static class KeepaliveDeviceConfigurationException extends AndroidRuntimeException {
          public KeepaliveDeviceConfigurationException(final String msg) {
              super(msg);
          }
      }
  
      /**
       * Read supported keepalive count for each transport type from overlay resource. This should be
       * used to create a local variable store of resource customization, and use it as the input for
       * {@link getSupportedKeepalivesForNetworkCapabilities}.
       *
       * @param context The context to read resource from.
       * @return An array of supported keepalive count for each transport type.
       */
      @NonNull
      public static int[] getSupportedKeepalives(@NonNull Context context) {
          String[] res = null;
          try {
              res = context.getResources().getStringArray(
                      R.array.config_networkSupportedKeepaliveCount);
          } catch (Resources.NotFoundException unused) {
          }
          if (res == null) throw new KeepaliveDeviceConfigurationException("invalid resource");
  
          final int[] ret = new int[NetworkCapabilities.MAX_TRANSPORT + 1];
          for (final String row : res) {
              if (TextUtils.isEmpty(row)) {
                  throw new KeepaliveDeviceConfigurationException("Empty string");
              }
              final String[] arr = row.split(",");
              if (arr.length != 2) {
                  throw new KeepaliveDeviceConfigurationException("Invalid parameter length");
              }
  
              int transport;
              int supported;
              try {
                  transport = Integer.parseInt(arr[0]);
                  supported = Integer.parseInt(arr[1]);
              } catch (NumberFormatException e) {
                  throw new KeepaliveDeviceConfigurationException("Invalid number format");
              }
  
              if (!NetworkCapabilities.isValidTransport(transport)) {
                  throw new KeepaliveDeviceConfigurationException("Invalid transport " + transport);
              }
  
              if (supported < 0) {
                  throw new KeepaliveDeviceConfigurationException(
                          "Invalid supported count " + supported + " for "
                                  + NetworkCapabilities.transportNameOf(transport));
              }
              ret[transport] = supported;
          }
          return ret;
      }
  
      /**
       * Get supported keepalive count for the given {@link NetworkCapabilities}.
       *
       * @param supportedKeepalives An array of supported keepalive count for each transport type.
       * @param nc The {@link NetworkCapabilities} of the network the socket keepalive is on.
       *
       * @return Supported keepalive count for the given {@link NetworkCapabilities}.
       */
      public static int getSupportedKeepalivesForNetworkCapabilities(
              @NonNull int[] supportedKeepalives, @NonNull NetworkCapabilities nc) {
          final int[] transports = nc.getTransportTypes();
          if (transports.length == 0) return 0;
          int supportedCount = supportedKeepalives[transports[0]];
          // Iterate through transports and return minimum supported value.
          for (final int transport : transports) {
              if (supportedCount > supportedKeepalives[transport]) {
                  supportedCount = supportedKeepalives[transport];
              }
          }
          return supportedCount;
      }
  }
  