1 /* 2 * Copyright (C) 2019 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.android.car.trust; 18 19 import android.annotation.NonNull; 20 import android.annotation.Nullable; 21 import android.bluetooth.BluetoothDevice; 22 import android.bluetooth.BluetoothGattCharacteristic; 23 import android.os.Handler; 24 import android.os.Looper; 25 import android.util.Log; 26 27 import com.android.car.BLEStreamProtos.VersionExchangeProto.BLEVersionExchange; 28 29 /** 30 * Resolver of version exchanges between this device and a client device. 31 */ 32 class BLEVersionExchangeResolver { 33 private static final String TAG = "BLEVersionExchangeResolver"; 34 35 // Currently, only version 1 of the messaging and security supported. 36 private static final int MESSAGING_VERSION = 1; 37 private static final int SECURITY_VERSION = 1; 38 39 /** 40 * Returns a message stream that can be used to send messages to the given 41 * {@link BluetoothDevice} based on the version exchange proto. 42 * 43 * @param versionExchange The version exchange proto to resolve 44 * @param device The remote device to send messages to. 45 * @param readCharacteristic The characteristic the remote device will use to write messages to. 46 * This is the characteristic this IHU will read from. 47 * @param writeCharacteristic The characteristic on the remote device that this IHU can write 48 * messages to. 49 * @return A stream that can send message or {@code null} if resolution was not possible. 50 */ 51 @Nullable resolveToStream( @onNull BLEVersionExchange versionExchange, @NonNull BluetoothDevice device, @NonNull BlePeripheralManager blePeripheralManager, @NonNull BluetoothGattCharacteristic writeCharacteristic, @NonNull BluetoothGattCharacteristic readCharacteristic)52 static BleMessageStream resolveToStream( 53 @NonNull BLEVersionExchange versionExchange, 54 @NonNull BluetoothDevice device, @NonNull BlePeripheralManager blePeripheralManager, 55 @NonNull BluetoothGattCharacteristic writeCharacteristic, 56 @NonNull BluetoothGattCharacteristic readCharacteristic) { 57 int minMessagingVersion = versionExchange.getMinSupportedMessagingVersion(); 58 int minSecurityVersion = versionExchange.getMinSupportedSecurityVersion(); 59 60 if (Log.isLoggable(TAG, Log.DEBUG)) { 61 Log.d(TAG, "Checking for supported version on (minMessagingVersion: " 62 + minMessagingVersion + ", minSecurityVersion: " + minSecurityVersion + ")"); 63 } 64 65 // Only one supported version, so ensure the minimum version matches. 66 if (minMessagingVersion == MESSAGING_VERSION && minSecurityVersion == SECURITY_VERSION) { 67 return new BleMessageStreamV1( 68 new Handler(Looper.getMainLooper()), 69 blePeripheralManager, 70 device, 71 writeCharacteristic, 72 readCharacteristic); 73 } 74 75 return null; 76 } 77 78 /** 79 * Returns a version exchange proto with the maximum and minimum protocol and security versions 80 * this device currently supports. 81 */ 82 @NonNull makeVersionExchange()83 static BLEVersionExchange makeVersionExchange() { 84 return BLEVersionExchange.newBuilder() 85 .setMinSupportedMessagingVersion(MESSAGING_VERSION) 86 .setMaxSupportedMessagingVersion(MESSAGING_VERSION) 87 .setMinSupportedSecurityVersion(SECURITY_VERSION) 88 .setMaxSupportedSecurityVersion(SECURITY_VERSION) 89 .build(); 90 } 91 BLEVersionExchangeResolver()92 private BLEVersionExchangeResolver() {} 93 } 94