HdmiCecMessageValidator.java revision 2e8f1b6399089626b4f0249427626ba6e63a62ef 
1/*
2 * Copyright (C) 2014 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
17package com.android.server.hdmi;
18
19import android.hardware.hdmi.HdmiDeviceInfo;
20import android.util.SparseArray;
21
22/**
23 * A helper class to validates {@link HdmiCecMessage}.
24 */
25public final class HdmiCecMessageValidator {
26    private static final String TAG = "HdmiCecMessageValidator";
27
28    private final HdmiControlService mService;
29
30    interface ParameterValidator {
31        boolean isValid(byte[] params);
32    }
33
34    // Only the direct addressing is allowed.
35    private static final int DEST_DIRECT = 1 << 0;
36    // Only the broadcast addressing is allowed.
37    private static final int DEST_BROADCAST = 1 << 1;
38    // Both the direct and the broadcast addressing are allowed.
39    private static final int DEST_ALL = DEST_DIRECT | DEST_BROADCAST;
40    // True if the messages from address 15 (unregistered) are allowed.
41    private static final int SRC_UNREGISTERED = 1 << 2;
42
43    private static class ValidationInfo {
44        public final ParameterValidator parameterValidator;
45        public final int addressType;
46
47        public ValidationInfo(ParameterValidator validator, int type) {
48            parameterValidator = validator;
49            addressType = type;
50        }
51    }
52
53    final SparseArray<ValidationInfo> mValidationInfo = new SparseArray<>();
54
55    public HdmiCecMessageValidator(HdmiControlService service) {
56        mService = service;
57
58        // Messages related to the physical address.
59        PhysicalAddressValidator physicalAddressValidator = new PhysicalAddressValidator();
60        addValidationInfo(Constants.MESSAGE_ACTIVE_SOURCE,
61                physicalAddressValidator, DEST_BROADCAST | SRC_UNREGISTERED);
62        addValidationInfo(Constants.MESSAGE_INACTIVE_SOURCE, physicalAddressValidator, DEST_DIRECT);
63        addValidationInfo(Constants.MESSAGE_REPORT_PHYSICAL_ADDRESS,
64                new ReportPhysicalAddressValidator(), DEST_BROADCAST | SRC_UNREGISTERED);
65        addValidationInfo(Constants.MESSAGE_ROUTING_CHANGE,
66                new RoutingChangeValidator(), DEST_BROADCAST | SRC_UNREGISTERED);
67        addValidationInfo(Constants.MESSAGE_ROUTING_INFORMATION,
68                physicalAddressValidator, DEST_BROADCAST | SRC_UNREGISTERED);
69        addValidationInfo(Constants.MESSAGE_SET_STREAM_PATH,
70                physicalAddressValidator, DEST_BROADCAST);
71        addValidationInfo(Constants.MESSAGE_SYSTEM_AUDIO_MODE_REQUEST,
72                physicalAddressValidator, DEST_DIRECT);
73
74        // Messages have no parameter.
75        FixedLengthValidator noneValidator = new FixedLengthValidator(0);
76        addValidationInfo(Constants.MESSAGE_ABORT, noneValidator, DEST_DIRECT);
77        addValidationInfo(Constants.MESSAGE_GET_CEC_VERSION, noneValidator, DEST_DIRECT);
78        addValidationInfo(Constants.MESSAGE_GET_MENU_LANGUAGE,
79                noneValidator, DEST_DIRECT | SRC_UNREGISTERED);
80        addValidationInfo(Constants.MESSAGE_GIVE_AUDIO_STATUS, noneValidator, DEST_DIRECT);
81        addValidationInfo(Constants.MESSAGE_GIVE_DEVICE_POWER_STATUS, noneValidator, DEST_DIRECT);
82        addValidationInfo(Constants.MESSAGE_GIVE_DEVICE_VENDOR_ID,
83                noneValidator, DEST_DIRECT | SRC_UNREGISTERED);
84        addValidationInfo(Constants.MESSAGE_GIVE_OSD_NAME, noneValidator, DEST_DIRECT);
85        addValidationInfo(Constants.MESSAGE_GIVE_PHYSICAL_ADDRESS,
86                noneValidator, DEST_DIRECT | SRC_UNREGISTERED);
87        addValidationInfo(Constants.MESSAGE_GIVE_SYSTEM_AUDIO_MODE_STATUS,
88                noneValidator, DEST_DIRECT);
89        addValidationInfo(Constants.MESSAGE_IMAGE_VIEW_ON, noneValidator, DEST_DIRECT);
90        addValidationInfo(Constants.MESSAGE_INITIATE_ARC, noneValidator, DEST_DIRECT);
91        addValidationInfo(Constants.MESSAGE_RECORD_OFF, noneValidator, DEST_DIRECT);
92        addValidationInfo(Constants.MESSAGE_RECORD_TV_SCREEN, noneValidator, DEST_DIRECT);
93        addValidationInfo(Constants.MESSAGE_REPORT_ARC_INITIATED, noneValidator, DEST_DIRECT);
94        addValidationInfo(Constants.MESSAGE_REPORT_ARC_TERMINATED, noneValidator, DEST_DIRECT);
95        addValidationInfo(Constants.MESSAGE_REQUEST_ARC_INITIATION, noneValidator, DEST_DIRECT);
96        addValidationInfo(Constants.MESSAGE_REQUEST_ARC_TERMINATION, noneValidator, DEST_DIRECT);
97        addValidationInfo(Constants.MESSAGE_REQUEST_ACTIVE_SOURCE,
98                noneValidator, DEST_BROADCAST | SRC_UNREGISTERED);
99        addValidationInfo(Constants.MESSAGE_STANDBY, noneValidator, DEST_ALL | SRC_UNREGISTERED);
100        addValidationInfo(Constants.MESSAGE_TERMINATE_ARC, noneValidator, DEST_DIRECT);
101        addValidationInfo(Constants.MESSAGE_TEXT_VIEW_ON, noneValidator, DEST_DIRECT);
102        addValidationInfo(Constants.MESSAGE_TUNER_STEP_DECREMENT, noneValidator, DEST_DIRECT);
103        addValidationInfo(Constants.MESSAGE_TUNER_STEP_INCREMENT, noneValidator, DEST_DIRECT);
104        addValidationInfo(Constants.MESSAGE_USER_CONTROL_RELEASED, noneValidator, DEST_DIRECT);
105        addValidationInfo(Constants.MESSAGE_VENDOR_REMOTE_BUTTON_UP, noneValidator, DEST_ALL);
106
107        // TODO: Validate more than length for the following messages.
108
109        // Messages for the One Touch Record.
110        FixedLengthValidator oneByteValidator = new FixedLengthValidator(1);
111        addValidationInfo(Constants.MESSAGE_RECORD_ON,
112                new VariableLengthValidator(1, 8), DEST_DIRECT);
113        addValidationInfo(Constants.MESSAGE_RECORD_STATUS, oneByteValidator, DEST_DIRECT);
114
115        // TODO: Handle messages for the Timer Programming.
116
117        // Messages for the System Information.
118        addValidationInfo(Constants.MESSAGE_CEC_VERSION, oneByteValidator, DEST_DIRECT);
119        addValidationInfo(Constants.MESSAGE_SET_MENU_LANGUAGE,
120                new FixedLengthValidator(3), DEST_BROADCAST);
121
122        // TODO: Handle messages for the Deck Control.
123
124        // TODO: Handle messages for the Tuner Control.
125
126        // Messages for the Vendor Specific Commands.
127        VariableLengthValidator maxLengthValidator = new VariableLengthValidator(0, 14);
128        addValidationInfo(Constants.MESSAGE_DEVICE_VENDOR_ID,
129                new FixedLengthValidator(3), DEST_BROADCAST);
130        // Allow unregistered source for all vendor specific commands, because we don't know
131        // how to use the commands at this moment.
132        addValidationInfo(Constants.MESSAGE_VENDOR_COMMAND,
133                maxLengthValidator, DEST_DIRECT | SRC_UNREGISTERED);
134        addValidationInfo(Constants.MESSAGE_VENDOR_COMMAND_WITH_ID,
135                maxLengthValidator, DEST_ALL | SRC_UNREGISTERED);
136        addValidationInfo(Constants.MESSAGE_VENDOR_REMOTE_BUTTON_DOWN,
137                maxLengthValidator, DEST_ALL | SRC_UNREGISTERED);
138
139        // Messages for the OSD.
140        addValidationInfo(Constants.MESSAGE_SET_OSD_STRING, maxLengthValidator, DEST_DIRECT);
141        addValidationInfo(Constants.MESSAGE_SET_OSD_NAME, maxLengthValidator, DEST_DIRECT);
142
143        // TODO: Handle messages for the Device Menu Control.
144
145        // Messages for the Remote Control Passthrough.
146        // TODO: Parse the first parameter and determine if it can have the next parameter.
147        addValidationInfo(Constants.MESSAGE_USER_CONTROL_PRESSED,
148                new VariableLengthValidator(1, 2), DEST_DIRECT);
149
150        // Messages for the Power Status.
151        addValidationInfo(Constants.MESSAGE_REPORT_POWER_STATUS, oneByteValidator, DEST_DIRECT);
152
153        // Messages for the General Protocol.
154        addValidationInfo(Constants.MESSAGE_FEATURE_ABORT,
155                new FixedLengthValidator(2), DEST_DIRECT);
156
157        // Messages for the System Audio Control.
158        addValidationInfo(Constants.MESSAGE_REPORT_AUDIO_STATUS, oneByteValidator, DEST_DIRECT);
159        addValidationInfo(Constants.MESSAGE_REPORT_SHORT_AUDIO_DESCRIPTOR,
160                new FixedLengthValidator(3), DEST_DIRECT);
161        addValidationInfo(Constants.MESSAGE_REQUEST_SHORT_AUDIO_DESCRIPTOR,
162                oneByteValidator, DEST_DIRECT);
163        addValidationInfo(Constants.MESSAGE_SET_SYSTEM_AUDIO_MODE, oneByteValidator, DEST_ALL);
164        addValidationInfo(Constants.MESSAGE_SYSTEM_AUDIO_MODE_STATUS,
165                oneByteValidator, DEST_DIRECT);
166
167        // Messages for the Audio Rate Control.
168        addValidationInfo(Constants.MESSAGE_SET_AUDIO_RATE, oneByteValidator, DEST_DIRECT);
169
170        // All Messages for the ARC have no parameters.
171
172        // Messages for the Capability Discovery and Control.
173        addValidationInfo(Constants.MESSAGE_CDC_MESSAGE, maxLengthValidator,
174                DEST_BROADCAST | SRC_UNREGISTERED);
175    }
176
177    private void addValidationInfo(int opcode, ParameterValidator validator, int addrType) {
178        mValidationInfo.append(opcode, new ValidationInfo(validator, addrType));
179    }
180
181    boolean isValid(HdmiCecMessage message) {
182        int opcode = message.getOpcode();
183        ValidationInfo info = mValidationInfo.get(opcode);
184        if (info == null) {
185            HdmiLogger.warning("No validation information for the message: " + message);
186            return true;
187        }
188
189        // Check the source field.
190        if (message.getSource() == Constants.ADDR_UNREGISTERED &&
191                (info.addressType & SRC_UNREGISTERED) == 0) {
192            HdmiLogger.warning("Unexpected source: " + message);
193            return false;
194        }
195        // Check the destination field.
196        if (message.getDestination() == Constants.ADDR_BROADCAST) {
197            if ((info.addressType & DEST_BROADCAST) == 0) {
198                HdmiLogger.warning("Unexpected broadcast message: " + message);
199                return false;
200            }
201        } else {  // Direct addressing.
202            if ((info.addressType & DEST_DIRECT) == 0) {
203                HdmiLogger.warning("Unexpected direct message: " + message);
204                return false;
205            }
206        }
207
208        // Check the parameter type.
209        if (!info.parameterValidator.isValid(message.getParams())) {
210            HdmiLogger.warning("Unexpected parameters: " + message);
211            return false;
212        }
213        return true;
214    }
215
216    private static class FixedLengthValidator implements ParameterValidator {
217        private final int mLength;
218
219        public FixedLengthValidator(int length) {
220            mLength = length;
221        }
222
223        @Override
224        public boolean isValid(byte[] params) {
225            return params.length == mLength;
226        }
227    }
228
229    private static class VariableLengthValidator implements ParameterValidator {
230        private final int mMinLength;
231        private final int mMaxLength;
232
233        public VariableLengthValidator(int minLength, int maxLength) {
234            mMinLength = minLength;
235            mMaxLength = maxLength;
236        }
237
238        @Override
239        public boolean isValid(byte[] params) {
240            return params.length >= mMinLength && params.length <= mMaxLength;
241        }
242    }
243
244    private boolean isValidPhysicalAddress(byte[] params, int offset) {
245        // TODO: Add more logic like validating 1.0.1.0.
246
247        if (!mService.isTvDevice()) {
248            // If the device is not TV, we can't convert path to port-id, so stop here.
249            return true;
250        }
251        int path = HdmiUtils.twoBytesToInt(params, offset);
252        if (path != Constants.INVALID_PHYSICAL_ADDRESS && path == mService.getPhysicalAddress()) {
253            return true;
254        }
255        int portId = mService.pathToPortId(path);
256        if (portId == Constants.INVALID_PORT_ID) {
257            return false;
258        }
259        return true;
260    }
261
262    /**
263     * Check if the given type is valid. A valid type is one of the actual logical device types
264     * defined in the standard ({@link HdmiDeviceInfo#DEVICE_TV},
265     * {@link HdmiDeviceInfo#DEVICE_PLAYBACK}, {@link HdmiDeviceInfo#DEVICE_TUNER},
266     * {@link HdmiDeviceInfo#DEVICE_RECORDER}, and
267     * {@link HdmiDeviceInfo#DEVICE_AUDIO_SYSTEM}).
268     *
269     * @param type device type
270     * @return true if the given type is valid
271     */
272    static boolean isValidType(int type) {
273        return (HdmiDeviceInfo.DEVICE_TV <= type
274                && type <= HdmiDeviceInfo.DEVICE_VIDEO_PROCESSOR)
275                && type != HdmiDeviceInfo.DEVICE_RESERVED;
276    }
277
278    private class PhysicalAddressValidator implements ParameterValidator {
279        @Override
280        public boolean isValid(byte[] params) {
281            if (params.length != 2) {
282                return false;
283            }
284            return isValidPhysicalAddress(params, 0);
285        }
286    }
287
288    private class ReportPhysicalAddressValidator implements ParameterValidator {
289        @Override
290        public boolean isValid(byte[] params) {
291            if (params.length != 3) {
292                return false;
293            }
294            return isValidPhysicalAddress(params, 0) && isValidType(params[2]);
295        }
296    }
297
298    private class RoutingChangeValidator implements ParameterValidator {
299        @Override
300        public boolean isValid(byte[] params) {
301            if (params.length != 4) {
302                return false;
303            }
304            return isValidPhysicalAddress(params, 0) && isValidPhysicalAddress(params, 2);
305        }
306    }
307}
308