ConfigUpdateInstallReceiver.java revision 3f72604be806c0173b5dca0225cadf6e7c872147 
1/*
2 * Copyright (C) 2012 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.updates;
18
19import com.android.server.EventLogTags;
20import com.android.internal.util.HexDump;
21
22import android.content.BroadcastReceiver;
23import android.content.Context;
24import android.content.Intent;
25import android.net.Uri;
26import android.util.EventLog;
27import android.util.Slog;
28
29import java.io.File;
30import java.io.FileOutputStream;
31import java.io.IOException;
32import java.io.InputStream;
33import java.security.MessageDigest;
34import java.security.NoSuchAlgorithmException;
35
36import libcore.io.IoUtils;
37import libcore.io.Streams;
38
39public class ConfigUpdateInstallReceiver extends BroadcastReceiver {
40
41    private static final String TAG = "ConfigUpdateInstallReceiver";
42
43    private static final String EXTRA_REQUIRED_HASH = "REQUIRED_HASH";
44    private static final String EXTRA_VERSION_NUMBER = "VERSION";
45
46    protected final File updateDir;
47    protected final File updateContent;
48    protected final File updateVersion;
49
50    public ConfigUpdateInstallReceiver(String updateDir, String updateContentPath,
51                                       String updateMetadataPath, String updateVersionPath) {
52        this.updateDir = new File(updateDir);
53        this.updateContent = new File(updateDir, updateContentPath);
54        File updateMetadataDir = new File(updateDir, updateMetadataPath);
55        this.updateVersion = new File(updateMetadataDir, updateVersionPath);
56    }
57
58    @Override
59    public void onReceive(final Context context, final Intent intent) {
60        new Thread() {
61            @Override
62            public void run() {
63                try {
64                    // get the content path from the extras
65                    byte[] altContent = getAltContent(context, intent);
66                    // get the version from the extras
67                    int altVersion = getVersionFromIntent(intent);
68                    // get the previous value from the extras
69                    String altRequiredHash = getRequiredHashFromIntent(intent);
70                    // get the version currently being used
71                    int currentVersion = getCurrentVersion();
72                    // get the hash of the currently used value
73                    String currentHash = getCurrentHash(getCurrentContent());
74                    if (!verifyVersion(currentVersion, altVersion)) {
75                        Slog.i(TAG, "Not installing, new version is <= current version");
76                    } else if (!verifyPreviousHash(currentHash, altRequiredHash)) {
77                        EventLog.writeEvent(EventLogTags.CONFIG_INSTALL_FAILED,
78                                            "Current hash did not match required value");
79                    } else {
80                        // install the new content
81                        Slog.i(TAG, "Found new update, installing...");
82                        install(altContent, altVersion);
83                        Slog.i(TAG, "Installation successful");
84                        postInstall(context, intent);
85                    }
86                } catch (Exception e) {
87                    Slog.e(TAG, "Could not update content!", e);
88                    // keep the error message <= 100 chars
89                    String errMsg = e.toString();
90                    if (errMsg.length() > 100) {
91                        errMsg = errMsg.substring(0, 99);
92                    }
93                    EventLog.writeEvent(EventLogTags.CONFIG_INSTALL_FAILED, errMsg);
94                }
95            }
96        }.start();
97    }
98
99    private Uri getContentFromIntent(Intent i) {
100        Uri data = i.getData();
101        if (data == null) {
102            throw new IllegalStateException("Missing required content path, ignoring.");
103        }
104        return data;
105    }
106
107    private int getVersionFromIntent(Intent i) throws NumberFormatException {
108        String extraValue = i.getStringExtra(EXTRA_VERSION_NUMBER);
109        if (extraValue == null) {
110            throw new IllegalStateException("Missing required version number, ignoring.");
111        }
112        return Integer.parseInt(extraValue.trim());
113    }
114
115    private String getRequiredHashFromIntent(Intent i) {
116        String extraValue = i.getStringExtra(EXTRA_REQUIRED_HASH);
117        if (extraValue == null) {
118            throw new IllegalStateException("Missing required previous hash, ignoring.");
119        }
120        return extraValue.trim();
121    }
122
123    private int getCurrentVersion() throws NumberFormatException {
124        try {
125            String strVersion = IoUtils.readFileAsString(updateVersion.getCanonicalPath()).trim();
126            return Integer.parseInt(strVersion);
127        } catch (IOException e) {
128            Slog.i(TAG, "Couldn't find current metadata, assuming first update");
129            return 0;
130        }
131    }
132
133    private byte[] getAltContent(Context c, Intent i) throws IOException {
134        Uri content = getContentFromIntent(i);
135        InputStream is = c.getContentResolver().openInputStream(content);
136        try {
137            return Streams.readFullyNoClose(is);
138        } finally {
139            is.close();
140        }
141    }
142
143    private byte[] getCurrentContent() {
144        try {
145            return IoUtils.readFileAsByteArray(updateContent.getCanonicalPath());
146        } catch (IOException e) {
147            Slog.i(TAG, "Failed to read current content, assuming first update!");
148            return null;
149        }
150    }
151
152    private static String getCurrentHash(byte[] content) {
153        if (content == null) {
154            return "0";
155        }
156        try {
157            MessageDigest dgst = MessageDigest.getInstance("SHA512");
158            byte[] fingerprint = dgst.digest(content);
159            return HexDump.toHexString(fingerprint, false);
160        } catch (NoSuchAlgorithmException e) {
161            throw new AssertionError(e);
162        }
163    }
164
165    private boolean verifyVersion(int current, int alternative) {
166        return (current < alternative);
167    }
168
169    private boolean verifyPreviousHash(String current, String required) {
170        // this is an optional value- if the required field is NONE then we ignore it
171        if (required.equals("NONE")) {
172            return true;
173        }
174        // otherwise, verify that we match correctly
175        return current.equals(required);
176    }
177
178    protected void writeUpdate(File dir, File file, byte[] content) throws IOException {
179        FileOutputStream out = null;
180        File tmp = null;
181        try {
182            // create the parents for the destination file
183            File parent = file.getParentFile();
184            parent.mkdirs();
185            // check that they were created correctly
186            if (!parent.exists()) {
187                throw new IOException("Failed to create directory " + parent.getCanonicalPath());
188            }
189            // create the temporary file
190            tmp = File.createTempFile("journal", "", dir);
191            // mark tmp -rw-r--r--
192            tmp.setReadable(true, false);
193            // write to it
194            out = new FileOutputStream(tmp);
195            out.write(content);
196            // sync to disk
197            out.getFD().sync();
198            // atomic rename
199            if (!tmp.renameTo(file)) {
200                throw new IOException("Failed to atomically rename " + file.getCanonicalPath());
201            }
202        } finally {
203            if (tmp != null) {
204                tmp.delete();
205            }
206            IoUtils.closeQuietly(out);
207        }
208    }
209
210    protected void install(byte[] content, int version) throws IOException {
211        writeUpdate(updateDir, updateContent, content);
212        writeUpdate(updateDir, updateVersion, Long.toString(version).getBytes());
213    }
214
215    protected void postInstall(Context context, Intent intent) {
216    }
217}
218