HdmiCecMessageValidator.java revision 61f4fbd2e8436a1ecd478c2a1f516d064a24d43b 
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.Slog;
21import android.util.SparseArray;
22
23/**
24 * A helper class to validates {@link HdmiCecMessage}.
25 */
26public final class HdmiCecMessageValidator {
27    private static final String TAG = "HdmiCecMessageValidator";
28
29    private final HdmiControlService mService;
30
31    interface ParameterValidator {
32        boolean isValid(byte[] params);
33    }
34
35    // Only the direct addressing is allowed.
36    private static final int DEST_DIRECT = 1 << 0;
37    // Only the broadcast addressing is allowed.
38    private static final int DEST_BROADCAST = 1 << 1;
39    // Both the direct and the broadcast addressing are allowed.
40    private static final int DEST_ALL = DEST_DIRECT | DEST_BROADCAST;
41    // True if the messages from address 15 (unregistered) are allowed.
42    private static final int SRC_UNREGISTERED = 1 << 2;
43
44    private static class ValidationInfo {
45        public final ParameterValidator parameterValidator;
46        public final int addressType;
47
48        public ValidationInfo(ParameterValidator validator, int type) {
49            parameterValidator = validator;
50            addressType = type;
51        }
52    }
53
54    final SparseArray<ValidationInfo> mValidationInfo = new SparseArray<>();
55
56    public HdmiCecMessageValidator(HdmiControlService service) {
57        mService = service;
58
59        // Messages related to the physical address.
60        PhysicalAddressValidator physicalAddressValidator = new PhysicalAddressValidator();
61        addValidationInfo(Constants.MESSAGE_ACTIVE_SOURCE,
62                physicalAddressValidator, DEST_BROADCAST | SRC_UNREGISTERED);
63        addValidationInfo(Constants.MESSAGE_INACTIVE_SOURCE, physicalAddressValidator, DEST_DIRECT);
64        addValidationInfo(Constants.MESSAGE_REPORT_PHYSICAL_ADDRESS,
65                new ReportPhysicalAddressValidator(), DEST_BROADCAST | SRC_UNREGISTERED);
66        addValidationInfo(Constants.MESSAGE_ROUTING_CHANGE,
67                new RoutingChangeValidator(), DEST_BROADCAST | SRC_UNREGISTERED);
68        addValidationInfo(Constants.MESSAGE_ROUTING_INFORMATION,
69                physicalAddressValidator, DEST_BROADCAST | SRC_UNREGISTERED);
70        addValidationInfo(Constants.MESSAGE_SET_STREAM_PATH,
71                physicalAddressValidator, DEST_BROADCAST);
72        addValidationInfo(Constants.MESSAGE_SYSTEM_AUDIO_MODE_REQUEST,
73                physicalAddressValidator, DEST_DIRECT);
74
75        // Messages have no parameter.
76        FixedLengthValidator noneValidator = new FixedLengthValidator(0);
77        addValidationInfo(Constants.MESSAGE_ABORT, noneValidator, DEST_DIRECT);
78        addValidationInfo(Constants.MESSAGE_GET_CEC_VERSION, noneValidator, DEST_DIRECT);
79        addValidationInfo(Constants.MESSAGE_GET_MENU_LANGUAGE,
80                noneValidator, DEST_DIRECT | SRC_UNREGISTERED);
81        addValidationInfo(Constants.MESSAGE_GIVE_AUDIO_STATUS, noneValidator, DEST_DIRECT);
82        addValidationInfo(Constants.MESSAGE_GIVE_DEVICE_POWER_STATUS, noneValidator, DEST_DIRECT);
83        addValidationInfo(Constants.MESSAGE_GIVE_DEVICE_VENDOR_ID,
84                noneValidator, DEST_DIRECT | SRC_UNREGISTERED);
85        addValidationInfo(Constants.MESSAGE_GIVE_OSD_NAME, noneValidator, DEST_DIRECT);
86        addValidationInfo(Constants.MESSAGE_GIVE_PHYSICAL_ADDRESS,
87                noneValidator, DEST_DIRECT | SRC_UNREGISTERED);
88        addValidationInfo(Constants.MESSAGE_GIVE_SYSTEM_AUDIO_MODE_STATUS,
89                noneValidator, DEST_DIRECT);
90        addValidationInfo(Constants.MESSAGE_IMAGE_VIEW_ON, noneValidator, DEST_DIRECT);
91        addValidationInfo(Constants.MESSAGE_INITIATE_ARC, noneValidator, DEST_DIRECT);
92        addValidationInfo(Constants.MESSAGE_RECORD_OFF, noneValidator, DEST_DIRECT);
93        addValidationInfo(Constants.MESSAGE_RECORD_TV_SCREEN, noneValidator, DEST_DIRECT);
94        addValidationInfo(Constants.MESSAGE_REPORT_ARC_INITIATED, noneValidator, DEST_DIRECT);
95        addValidationInfo(Constants.MESSAGE_REPORT_ARC_TERMINATED, noneValidator, DEST_DIRECT);
96        addValidationInfo(Constants.MESSAGE_REQUEST_ARC_INITIATION, noneValidator, DEST_DIRECT);
97        addValidationInfo(Constants.MESSAGE_REQUEST_ARC_TERMINATION, noneValidator, DEST_DIRECT);
98        addValidationInfo(Constants.MESSAGE_REQUEST_ACTIVE_SOURCE,
99                noneValidator, DEST_BROADCAST | SRC_UNREGISTERED);
100        addValidationInfo(Constants.MESSAGE_STANDBY, noneValidator, DEST_ALL | SRC_UNREGISTERED);
101        addValidationInfo(Constants.MESSAGE_TERMINATE_ARC, noneValidator, DEST_DIRECT);
102        addValidationInfo(Constants.MESSAGE_TEXT_VIEW_ON, noneValidator, DEST_DIRECT);
103        addValidationInfo(Constants.MESSAGE_TUNER_STEP_DECREMENT, noneValidator, DEST_DIRECT);
104        addValidationInfo(Constants.MESSAGE_TUNER_STEP_INCREMENT, noneValidator, DEST_DIRECT);
105        addValidationInfo(Constants.MESSAGE_USER_CONTROL_RELEASED, noneValidator, DEST_DIRECT);
106        addValidationInfo(Constants.MESSAGE_VENDOR_REMOTE_BUTTON_UP, noneValidator, DEST_ALL);
107
108        // TODO: Validate more than length for the following messages.
109
110        // Messages for the One Touch Record.
111        FixedLengthValidator oneByteValidator = new FixedLengthValidator(1);
112        addValidationInfo(Constants.MESSAGE_RECORD_ON,
113                new VariableLengthValidator(1, 8), DEST_DIRECT);
114        addValidationInfo(Constants.MESSAGE_RECORD_STATUS, oneByteValidator, DEST_DIRECT);
115
116        // TODO: Handle messages for the Timer Programming.
117
118        // Messages for the System Information.
119        addValidationInfo(Constants.MESSAGE_CEC_VERSION, oneByteValidator, DEST_DIRECT);
120        addValidationInfo(Constants.MESSAGE_SET_MENU_LANGUAGE,
121                new FixedLengthValidator(3), DEST_BROADCAST);
122
123        // TODO: Handle messages for the Deck Control.
124
125        // TODO: Handle messages for the Tuner Control.
126
127        // Messages for the Vendor Specific Commands.
128        VariableLengthValidator maxLengthValidator = new VariableLengthValidator(0, 14);
129        addValidationInfo(Constants.MESSAGE_DEVICE_VENDOR_ID,
130                new FixedLengthValidator(3), DEST_BROADCAST);
131        // Allow unregistered source for all vendor specific commands, because we don't know
132        // how to use the commands at this moment.
133        addValidationInfo(Constants.MESSAGE_VENDOR_COMMAND,
134                maxLengthValidator, DEST_DIRECT | SRC_UNREGISTERED);
135        addValidationInfo(Constants.MESSAGE_VENDOR_COMMAND_WITH_ID,
136                maxLengthValidator, DEST_ALL | SRC_UNREGISTERED);
137        addValidationInfo(Constants.MESSAGE_VENDOR_REMOTE_BUTTON_DOWN,
138                maxLengthValidator, DEST_ALL | SRC_UNREGISTERED);
139
140        // Messages for the OSD.
141        addValidationInfo(Constants.MESSAGE_SET_OSD_STRING, maxLengthValidator, DEST_DIRECT);
142        addValidationInfo(Constants.MESSAGE_SET_OSD_NAME, maxLengthValidator, DEST_DIRECT);
143
144        // TODO: Handle messages for the Device Menu Control.
145
146        // Messages for the Remote Control Passthrough.
147        // TODO: Parse the first parameter and determine if it can have the next parameter.
148        addValidationInfo(Constants.MESSAGE_USER_CONTROL_PRESSED,
149                new VariableLengthValidator(1, 2), DEST_DIRECT);
150
151        // Messages for the Power Status.
152        addValidationInfo(Constants.MESSAGE_REPORT_POWER_STATUS, oneByteValidator, DEST_DIRECT);
153
154        // Messages for the General Protocol.
155        addValidationInfo(Constants.MESSAGE_FEATURE_ABORT,
156                new FixedLengthValidator(2), DEST_DIRECT);
157
158        // Messages for the System Audio Control.
159        addValidationInfo(Constants.MESSAGE_REPORT_AUDIO_STATUS, oneByteValidator, DEST_DIRECT);
160        addValidationInfo(Constants.MESSAGE_REPORT_SHORT_AUDIO_DESCRIPTOR,
161                new FixedLengthValidator(3), DEST_DIRECT);
162        addValidationInfo(Constants.MESSAGE_REQUEST_SHORT_AUDIO_DESCRIPTOR,
163                oneByteValidator, DEST_DIRECT);
164        addValidationInfo(Constants.MESSAGE_SET_SYSTEM_AUDIO_MODE, oneByteValidator, DEST_ALL);
165        addValidationInfo(Constants.MESSAGE_SYSTEM_AUDIO_MODE_STATUS,
166                oneByteValidator, DEST_DIRECT);
167
168        // Messages for the Audio Rate Control.
169        addValidationInfo(Constants.MESSAGE_SET_AUDIO_RATE, oneByteValidator, DEST_DIRECT);
170
171        // All Messages for the ARC have no parameters.
172
173        // Messages for the Capability Discovery and Control.
174        addValidationInfo(Constants.MESSAGE_CDC_MESSAGE, maxLengthValidator,
175                DEST_BROADCAST | SRC_UNREGISTERED);
176    }
177
178    private void addValidationInfo(int opcode, ParameterValidator validator, int addrType) {
179        mValidationInfo.append(opcode, new ValidationInfo(validator, addrType));
180    }
181
182    boolean isValid(HdmiCecMessage message) {
183        int opcode = message.getOpcode();
184        ValidationInfo info = mValidationInfo.get(opcode);
185        if (info == null) {
186            Slog.w(TAG, "No validation information for the message: " + message);
187            return true;
188        }
189
190        // Check the source field.
191        if (message.getSource() == Constants.ADDR_UNREGISTERED &&
192                (info.addressType & SRC_UNREGISTERED) == 0) {
193            Slog.w(TAG, "Unexpected source: " + message);
194            return false;
195        }
196        // Check the destination field.
197        if (message.getDestination() == Constants.ADDR_BROADCAST) {
198            if ((info.addressType & DEST_BROADCAST) == 0) {
199                Slog.w(TAG, "Unexpected broadcast message: " + message);
200                return false;
201            }
202        } else {  // Direct addressing.
203            if ((info.addressType & DEST_DIRECT) == 0) {
204                Slog.w(TAG, "Unexpected direct message: " + message);
205                return false;
206            }
207        }
208
209        // Check the parameter type.
210        if (!info.parameterValidator.isValid(message.getParams())) {
211            Slog.w(TAG, "Unexpected parameters: " + message);
212            return false;
213        }
214        return true;
215    }
216
217    private static class FixedLengthValidator implements ParameterValidator {
218        private final int mLength;
219
220        public FixedLengthValidator(int length) {
221            mLength = length;
222        }
223
224        @Override
225        public boolean isValid(byte[] params) {
226            return params.length == mLength;
227        }
228    }
229
230    private static class VariableLengthValidator implements ParameterValidator {
231        private final int mMinLength;
232        private final int mMaxLength;
233
234        public VariableLengthValidator(int minLength, int maxLength) {
235            mMinLength = minLength;
236            mMaxLength = maxLength;
237        }
238
239        @Override
240        public boolean isValid(byte[] params) {
241            return params.length >= mMinLength && params.length <= mMaxLength;
242        }
243    }
244
245    private boolean isValidPhysicalAddress(byte[] params, int offset) {
246        // TODO: Add more logic like validating 1.0.1.0.
247
248        if (!mService.isTvDevice()) {
249            // If the device is not TV, we can't convert path to port-id, so stop here.
250            return true;
251        }
252        int path = HdmiUtils.twoBytesToInt(params, offset);
253        int portId = mService.pathToPortId(path);
254        if (portId == Constants.INVALID_PORT_ID) {
255            return false;
256        }
257        return true;
258    }
259
260    /**
261     * Check if the given type is valid. A valid type is one of the actual logical device types
262     * defined in the standard ({@link HdmiCecDeviceInfo#DEVICE_TV},
263     * {@link HdmiCecDeviceInfo#DEVICE_PLAYBACK}, {@link HdmiCecDeviceInfo#DEVICE_TUNER},
264     * {@link HdmiCecDeviceInfo#DEVICE_RECORDER}, and
265     * {@link HdmiCecDeviceInfo#DEVICE_AUDIO_SYSTEM}).
266     *
267     * @param type device type
268     * @return true if the given type is valid
269     */
270    static boolean isValidType(int type) {
271        return (HdmiDeviceInfo.DEVICE_TV <= type
272                && type <= HdmiDeviceInfo.DEVICE_VIDEO_PROCESSOR)
273                && type != HdmiDeviceInfo.DEVICE_RESERVED;
274    }
275
276    private class PhysicalAddressValidator implements ParameterValidator {
277        @Override
278        public boolean isValid(byte[] params) {
279            if (params.length != 2) {
280                return false;
281            }
282            return isValidPhysicalAddress(params, 0);
283        }
284    }
285
286    private class ReportPhysicalAddressValidator implements ParameterValidator {
287        @Override
288        public boolean isValid(byte[] params) {
289            if (params.length != 3) {
290                return false;
291            }
292            return isValidPhysicalAddress(params, 0) && isValidType(params[2]);
293        }
294    }
295
296    private class RoutingChangeValidator implements ParameterValidator {
297        @Override
298        public boolean isValid(byte[] params) {
299            if (params.length != 4) {
300                return false;
301            }
302            return isValidPhysicalAddress(params, 0) && isValidPhysicalAddress(params, 2);
303        }
304    }
305}
306