ConfigUpdateInstallReceiver.java revision 12964bf5dd36d13fc25efef7c7175a677f9490a5 
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;
20
21import android.content.BroadcastReceiver;
22import android.content.Context;
23import android.content.Intent;
24import android.net.Uri;
25import android.util.EventLog;
26import android.util.Slog;
27
28import java.io.File;
29import java.io.FileOutputStream;
30import java.io.IOException;
31import java.io.InputStream;
32import java.security.MessageDigest;
33import java.security.NoSuchAlgorithmException;
34
35import libcore.io.IoUtils;
36import libcore.io.Streams;
37
38public class ConfigUpdateInstallReceiver extends BroadcastReceiver {
39
40    private static final String TAG = "ConfigUpdateInstallReceiver";
41
42    private static final String EXTRA_REQUIRED_HASH = "REQUIRED_HASH";
43    private static final String EXTRA_VERSION_NUMBER = "VERSION";
44
45    protected final File updateDir;
46    protected final File updateContent;
47    protected final File updateVersion;
48
49    public ConfigUpdateInstallReceiver(String updateDir, String updateContentPath,
50                                       String updateMetadataPath, String updateVersionPath) {
51        this.updateDir = new File(updateDir);
52        this.updateContent = new File(updateDir, updateContentPath);
53        File updateMetadataDir = new File(updateDir, updateMetadataPath);
54        this.updateVersion = new File(updateMetadataDir, updateVersionPath);
55    }
56
57    @Override
58    public void onReceive(final Context context, final Intent intent) {
59        new Thread() {
60            @Override
61            public void run() {
62                try {
63                    // get the content path from the extras
64                    byte[] altContent = getAltContent(context, intent);
65                    // get the version from the extras
66                    int altVersion = getVersionFromIntent(intent);
67                    // get the previous value from the extras
68                    String altRequiredHash = getRequiredHashFromIntent(intent);
69                    // get the version currently being used
70                    int currentVersion = getCurrentVersion();
71                    // get the hash of the currently used value
72                    String currentHash = getCurrentHash(getCurrentContent());
73                    if (!verifyVersion(currentVersion, altVersion)) {
74                        Slog.i(TAG, "Not installing, new version is <= current version");
75                    } else if (!verifyPreviousHash(currentHash, altRequiredHash)) {
76                        EventLog.writeEvent(EventLogTags.CONFIG_INSTALL_FAILED,
77                                            "Current hash did not match required value");
78                    } else {
79                        // install the new content
80                        Slog.i(TAG, "Found new update, installing...");
81                        install(altContent, altVersion);
82                        Slog.i(TAG, "Installation successful");
83                        postInstall(context, intent);
84                    }
85                } catch (Exception e) {
86                    Slog.e(TAG, "Could not update content!", e);
87                    // keep the error message <= 100 chars
88                    String errMsg = e.toString();
89                    if (errMsg.length() > 100) {
90                        errMsg = errMsg.substring(0, 99);
91                    }
92                    EventLog.writeEvent(EventLogTags.CONFIG_INSTALL_FAILED, errMsg);
93                }
94            }
95        }.start();
96    }
97
98    private Uri getContentFromIntent(Intent i) {
99        Uri data = i.getData();
100        if (data == null) {
101            throw new IllegalStateException("Missing required content path, ignoring.");
102        }
103        return data;
104    }
105
106    private int getVersionFromIntent(Intent i) throws NumberFormatException {
107        String extraValue = i.getStringExtra(EXTRA_VERSION_NUMBER);
108        if (extraValue == null) {
109            throw new IllegalStateException("Missing required version number, ignoring.");
110        }
111        return Integer.parseInt(extraValue.trim());
112    }
113
114    private String getRequiredHashFromIntent(Intent i) {
115        String extraValue = i.getStringExtra(EXTRA_REQUIRED_HASH);
116        if (extraValue == null) {
117            throw new IllegalStateException("Missing required previous hash, ignoring.");
118        }
119        return extraValue.trim();
120    }
121
122    private int getCurrentVersion() throws NumberFormatException {
123        try {
124            String strVersion = IoUtils.readFileAsString(updateVersion.getCanonicalPath()).trim();
125            return Integer.parseInt(strVersion);
126        } catch (IOException e) {
127            Slog.i(TAG, "Couldn't find current metadata, assuming first update");
128            return 0;
129        }
130    }
131
132    private byte[] getAltContent(Context c, Intent i) throws IOException {
133        Uri content = getContentFromIntent(i);
134        InputStream is = c.getContentResolver().openInputStream(content);
135        try {
136            return Streams.readFullyNoClose(is);
137        } finally {
138            is.close();
139        }
140    }
141
142    private byte[] getCurrentContent() {
143        try {
144            return IoUtils.readFileAsByteArray(updateContent.getCanonicalPath());
145        } catch (IOException e) {
146            Slog.i(TAG, "Failed to read current content, assuming first update!");
147            return null;
148        }
149    }
150
151    private static String getCurrentHash(byte[] content) {
152        if (content == null) {
153            return "0";
154        }
155        try {
156            MessageDigest dgst = MessageDigest.getInstance("SHA512");
157            byte[] fingerprint = dgst.digest(content);
158            return IntegralToString.bytesToHexString(fingerprint, false);
159        } catch (NoSuchAlgorithmException e) {
160            throw new AssertionError(e);
161        }
162    }
163
164    private boolean verifyVersion(int current, int alternative) {
165        return (current < alternative);
166    }
167
168    private boolean verifyPreviousHash(String current, String required) {
169        // this is an optional value- if the required field is NONE then we ignore it
170        if (required.equals("NONE")) {
171            return true;
172        }
173        // otherwise, verify that we match correctly
174        return current.equals(required);
175    }
176
177    protected void writeUpdate(File dir, File file, byte[] content) throws IOException {
178        FileOutputStream out = null;
179        File tmp = null;
180        try {
181            // create the parents for the destination file
182            File parent = file.getParentFile();
183            parent.mkdirs();
184            // check that they were created correctly
185            if (!parent.exists()) {
186                throw new IOException("Failed to create directory " + parent.getCanonicalPath());
187            }
188            // create the temporary file
189            tmp = File.createTempFile("journal", "", dir);
190            // mark tmp -rw-r--r--
191            tmp.setReadable(true, false);
192            // write to it
193            out = new FileOutputStream(tmp);
194            out.write(content);
195            // sync to disk
196            out.getFD().sync();
197            // atomic rename
198            if (!tmp.renameTo(file)) {
199                throw new IOException("Failed to atomically rename " + file.getCanonicalPath());
200            }
201        } finally {
202            if (tmp != null) {
203                tmp.delete();
204            }
205            IoUtils.closeQuietly(out);
206        }
207    }
208
209    protected void install(byte[] content, int version) throws IOException {
210        writeUpdate(updateDir, updateContent, content);
211        writeUpdate(updateDir, updateVersion, Long.toString(version).getBytes());
212    }
213
214    protected void postInstall(Context context, Intent intent) {
215    }
216}
217