Read RestoreSets from encrypted backup metadata file

app/src/main/java/com/stevesoltys/backup/metadata/Metadata.kt

@@ -4,6 +4,7 @@ import android.os.Build
 import android.os.Build.VERSION.SDK_INT
 import com.stevesoltys.backup.header.VERSION
 import com.stevesoltys.backup.transport.DEFAULT_RESTORE_SET_TOKEN
+import java.io.InputStream
 
 data class BackupMetadata(
         internal val version: Byte = VERSION,
@@ -18,3 +19,8 @@ internal const val JSON_ANDROID_VERSION = "androidVersion"
 internal const val JSON_DEVICE_NAME = "deviceName"
 
 class FormatException(cause: Throwable) : Exception(cause)
+
+class EncryptedBackupMetadata private constructor(val token: Long, val inputStream: InputStream?, val error: Boolean) {
+    constructor(token: Long, inputStream: InputStream) : this(token, inputStream, false)
+    constructor(token: Long, error: Boolean) : this(token, null, false)
+}

app/src/main/java/com/stevesoltys/backup/metadata/MetadataReader.kt

@@ -1,20 +1,36 @@
 package com.stevesoltys.backup.metadata
 
+import androidx.annotation.VisibleForTesting
 import com.stevesoltys.backup.Utf8
+import com.stevesoltys.backup.crypto.Crypto
+import com.stevesoltys.backup.header.UnsupportedVersionException
+import com.stevesoltys.backup.header.VERSION
 import org.json.JSONException
 import org.json.JSONObject
+import java.io.IOException
+import java.io.InputStream
 
-interface MetadataDecoder {
+interface MetadataReader {
 
-    @Throws(FormatException::class, SecurityException::class)
+    @Throws(FormatException::class, SecurityException::class, UnsupportedVersionException::class, IOException::class)
-    fun decode(bytes: ByteArray, expectedVersion: Byte, expectedToken: Long): BackupMetadata
+    fun readMetadata(inputStream: InputStream, expectedToken: Long): BackupMetadata
 
 }
 
-class MetadataDecoderImpl : MetadataDecoder {
+class MetadataReaderImpl(private val crypto: Crypto) : MetadataReader {
 
+    @Throws(FormatException::class, SecurityException::class, UnsupportedVersionException::class, IOException::class)
+    override fun readMetadata(inputStream: InputStream, expectedToken: Long): BackupMetadata {
+        val version = inputStream.read().toByte()
+        if (version < 0) throw IOException()
+        if (version > VERSION) throw UnsupportedVersionException(version)
+        val metadataBytes = crypto.decryptSegment(inputStream)
+        return decode(metadataBytes, version, expectedToken)
+    }
+
+    @VisibleForTesting
     @Throws(FormatException::class, SecurityException::class)
-    override fun decode(bytes: ByteArray, expectedVersion: Byte, expectedToken: Long): BackupMetadata {
+    internal fun decode(bytes: ByteArray, expectedVersion: Byte, expectedToken: Long): BackupMetadata {
         // NOTE: We don't do extensive validation of the parsed input here,
         // because it was encrypted with authentication, so we should be able to trust it.
         //
@@ -28,7 +44,7 @@ class MetadataDecoderImpl : MetadataDecoder {
             }
             val token = json.getLong(JSON_TOKEN)
             if (token != expectedToken) {
-                throw SecurityException("Invalid token '$expectedVersion' in metadata, expected '$expectedToken'.")
+                throw SecurityException("Invalid token '$token' in metadata, expected '$expectedToken'.")
             }
             return BackupMetadata(
                     version = version,

app/src/main/java/com/stevesoltys/backup/transport/PluginManager.kt

@@ -6,6 +6,7 @@ import com.stevesoltys.backup.crypto.CipherFactoryImpl
 import com.stevesoltys.backup.crypto.CryptoImpl
 import com.stevesoltys.backup.header.HeaderReaderImpl
 import com.stevesoltys.backup.header.HeaderWriterImpl
+import com.stevesoltys.backup.metadata.MetadataReaderImpl
 import com.stevesoltys.backup.metadata.MetadataWriterImpl
 import com.stevesoltys.backup.settings.getBackupFolderUri
 import com.stevesoltys.backup.settings.getDeviceName
@@ -32,6 +33,7 @@ class PluginManager(context: Context) {
     private val cipherFactory = CipherFactoryImpl(Backup.keyManager)
     private val crypto = CryptoImpl(cipherFactory, headerWriter, headerReader)
     private val metadataWriter = MetadataWriterImpl(crypto)
+    private val metadataReader = MetadataReaderImpl(crypto)
 
 
     private val backupPlugin = DocumentsProviderBackupPlugin(storage, context.packageManager)
@@ -48,6 +50,6 @@ class PluginManager(context: Context) {
     private val kvRestore = KVRestore(restorePlugin.kvRestorePlugin, outputFactory, headerReader, crypto)
     private val fullRestore = FullRestore(restorePlugin.fullRestorePlugin, outputFactory, headerReader, crypto)
 
-    internal val restoreCoordinator = RestoreCoordinator(restorePlugin, kvRestore, fullRestore)
+    internal val restoreCoordinator = RestoreCoordinator(restorePlugin, kvRestore, fullRestore, metadataReader)
 
 }

app/src/main/java/com/stevesoltys/backup/transport/restore/RestoreCoordinator.kt

@@ -8,6 +8,10 @@ import android.app.backup.RestoreSet
 import android.content.pm.PackageInfo
 import android.os.ParcelFileDescriptor
 import android.util.Log
+import com.stevesoltys.backup.header.UnsupportedVersionException
+import com.stevesoltys.backup.metadata.FormatException
+import com.stevesoltys.backup.metadata.MetadataReader
+import libcore.io.IoUtils.closeQuietly
 import java.io.IOException
 
 private class RestoreCoordinatorState(
@@ -19,13 +23,45 @@ private val TAG = RestoreCoordinator::class.java.simpleName
 internal class RestoreCoordinator(
         private val plugin: RestorePlugin,
         private val kv: KVRestore,
-        private val full: FullRestore) {
+        private val full: FullRestore,
+        private val metadataReader: MetadataReader) {
 
     private var state: RestoreCoordinatorState? = null
 
+    /**
+     * Get the set of all backups currently available over this transport.
+     *
+     * @return Descriptions of the set of restore images available for this device,
+     *   or null if an error occurred (the attempt should be rescheduled).
+     **/
     fun getAvailableRestoreSets(): Array<RestoreSet>? {
-        return plugin.getAvailableRestoreSets()
+        val availableBackups = plugin.getAvailableBackups() ?: return null
-                .apply { Log.i(TAG, "Got available restore sets: $this") }
+        val restoreSets = ArrayList<RestoreSet>()
+        for (encryptedMetadata in availableBackups) {
+            if (encryptedMetadata.error) continue
+            check(encryptedMetadata.inputStream != null)  // if there's no error, there must be a stream
+            try {
+                val metadata = metadataReader.readMetadata(encryptedMetadata.inputStream, encryptedMetadata.token)
+                val set = RestoreSet(metadata.deviceName, metadata.deviceName, metadata.token)
+                restoreSets.add(set)
+            } catch (e: IOException) {
+                Log.e(TAG, "Error while getting restore sets", e)
+                return null
+            } catch (e: FormatException) {
+                Log.e(TAG, "Error while getting restore sets", e)
+                return null
+            } catch (e: SecurityException) {
+                Log.e(TAG, "Error while getting restore sets", e)
+                return null
+            } catch (e: UnsupportedVersionException) {
+                Log.w(TAG, "Backup with unsupported version read", e)
+                continue
+            } finally {
+                closeQuietly(encryptedMetadata.inputStream)
+            }
+        }
+        Log.i(TAG, "Got available restore sets: $restoreSets")
+        return restoreSets.toTypedArray()
     }
 
     fun getCurrentRestoreSet(): Long {

app/src/main/java/com/stevesoltys/backup/transport/restore/RestorePlugin.kt

@@ -1,6 +1,6 @@
 package com.stevesoltys.backup.transport.restore
 
-import android.app.backup.RestoreSet
+import com.stevesoltys.backup.metadata.EncryptedBackupMetadata
 
 interface RestorePlugin {
 
@@ -11,10 +11,10 @@ interface RestorePlugin {
     /**
      * Get the set of all backups currently available for restore.
      *
-     * @return Descriptions of the set of restore images available for this device,
+     * @return metadata for the set of restore images available,
      * or null if an error occurred (the attempt should be rescheduled).
      **/
-    fun getAvailableRestoreSets(): Array<RestoreSet>?
+    fun getAvailableBackups(): Sequence<EncryptedBackupMetadata>?
 
     /**
      * Get the identifying token of the backup set currently being stored from this device.

app/src/main/java/com/stevesoltys/backup/transport/restore/plugins/DocumentsProviderRestorePlugin.kt

@@ -1,11 +1,17 @@
 package com.stevesoltys.backup.transport.restore.plugins
 
-import android.app.backup.RestoreSet
+import android.util.Log
+import androidx.documentfile.provider.DocumentFile
+import com.stevesoltys.backup.metadata.EncryptedBackupMetadata
 import com.stevesoltys.backup.transport.DEFAULT_RESTORE_SET_TOKEN
 import com.stevesoltys.backup.transport.backup.plugins.DocumentsStorage
+import com.stevesoltys.backup.transport.backup.plugins.FILE_BACKUP_METADATA
 import com.stevesoltys.backup.transport.restore.FullRestorePlugin
 import com.stevesoltys.backup.transport.restore.KVRestorePlugin
 import com.stevesoltys.backup.transport.restore.RestorePlugin
+import java.io.IOException
+
+private val TAG = DocumentsProviderRestorePlugin::class.java.simpleName
 
 class DocumentsProviderRestorePlugin(private val storage: DocumentsStorage) : RestorePlugin {
 
@@ -17,16 +23,28 @@ class DocumentsProviderRestorePlugin(private val storage: DocumentsStorage) : Re
         DocumentsProviderFullRestorePlugin(storage)
     }
 
-    override fun getAvailableRestoreSets(): Array<RestoreSet>? {
+    override fun getAvailableBackups(): Sequence<EncryptedBackupMetadata>? {
         val rootDir = storage.rootBackupDir ?: return null
-        val restoreSets = ArrayList<RestoreSet>()
+        val files = ArrayList<DocumentFile>()
         for (file in rootDir.listFiles()) {
-            if (file.isDirectory && file.findFile(DEFAULT_RESTORE_SET_TOKEN.toString()) != null) {
+            file.isDirectory || continue
-                // TODO include time of last backup
+            val set = file.findFile(DEFAULT_RESTORE_SET_TOKEN.toString()) ?: continue
-                file.name?.let { restoreSets.add(RestoreSet(it, it, DEFAULT_RESTORE_SET_TOKEN)) }
+            val metadata = set.findFile(FILE_BACKUP_METADATA) ?: continue
+            files.add(metadata)
+        }
+        val iterator = files.iterator()
+        return generateSequence {
+            if (!iterator.hasNext()) return@generateSequence null  // end sequence
+            val metadata = iterator.next()
+            val token = metadata.parentFile!!.name!!.toLong()
+            try {
+                val stream = storage.getInputStream(metadata)
+                EncryptedBackupMetadata(token, stream)
+            } catch (e: IOException) {
+                Log.e(TAG, "Error getting InputStream for backup metadata.", e)
+                EncryptedBackupMetadata(token, true)
             }
         }
-        return restoreSets.toTypedArray()
     }
 
     override fun getCurrentRestoreSet(): Long {

app/src/test/java/com/stevesoltys/backup/metadata/MetadataReaderTest.kt

@@ -12,12 +12,12 @@ import org.junit.jupiter.api.TestInstance.Lifecycle.PER_CLASS
 import kotlin.random.Random
 
 @TestInstance(PER_CLASS)
-class MetadataDecoderTest {
+class MetadataReaderTest {
 
     private val crypto = mockk<Crypto>()
 
     private val encoder = MetadataWriterImpl(crypto)
-    private val decoder = MetadataDecoderImpl()
+    private val decoder = MetadataReaderImpl(crypto)
 
     private val metadata = BackupMetadata(
             version = 1.toByte(),

app/src/test/java/com/stevesoltys/backup/metadata/MetadataWriterDecoderTest.kt

@@ -15,7 +15,7 @@ internal class MetadataWriterDecoderTest {
     private val crypto = mockk<Crypto>()
 
     private val encoder = MetadataWriterImpl(crypto)
-    private val decoder = MetadataDecoderImpl()
+    private val decoder = MetadataReaderImpl(crypto)
 
     private val metadata = BackupMetadata(
             version = Random.nextBytes(1)[0],

app/src/test/java/com/stevesoltys/backup/transport/CoordinatorIntegrationTest.kt

@@ -14,6 +14,7 @@ import com.stevesoltys.backup.crypto.KeyManagerTestImpl
 import com.stevesoltys.backup.encodeBase64
 import com.stevesoltys.backup.header.HeaderReaderImpl
 import com.stevesoltys.backup.header.HeaderWriterImpl
+import com.stevesoltys.backup.metadata.MetadataReaderImpl
 import com.stevesoltys.backup.metadata.MetadataWriterImpl
 import com.stevesoltys.backup.transport.backup.*
 import com.stevesoltys.backup.transport.restore.*
@@ -34,6 +35,7 @@ internal class CoordinatorIntegrationTest : TransportTest() {
     private val headerReader = HeaderReaderImpl()
     private val cryptoImpl = CryptoImpl(cipherFactory, headerWriter, headerReader)
     private val metadataWriter = MetadataWriterImpl(cryptoImpl)
+    private val metadataReader = MetadataReaderImpl(cryptoImpl)
 
     private val backupPlugin = mockk<BackupPlugin>()
     private val kvBackupPlugin = mockk<KVBackupPlugin>()
@@ -48,7 +50,7 @@ internal class CoordinatorIntegrationTest : TransportTest() {
     private val kvRestore = KVRestore(kvRestorePlugin, outputFactory, headerReader, cryptoImpl)
     private val fullRestorePlugin = mockk<FullRestorePlugin>()
     private val fullRestore = FullRestore(fullRestorePlugin, outputFactory, headerReader, cryptoImpl)
-    private val restore = RestoreCoordinator(restorePlugin, kvRestore, fullRestore)
+    private val restore = RestoreCoordinator(restorePlugin, kvRestore, fullRestore, metadataReader)
 
     private val backupDataInput = mockk<BackupDataInput>()
     private val fileDescriptor = mockk<ParcelFileDescriptor>(relaxed = true)

app/src/test/java/com/stevesoltys/backup/transport/restore/RestoreCoordinatorTest.kt

@@ -3,9 +3,12 @@ package com.stevesoltys.backup.transport.restore
 import android.app.backup.BackupTransport.TRANSPORT_OK
 import android.app.backup.RestoreDescription
 import android.app.backup.RestoreDescription.*
-import android.app.backup.RestoreSet
 import android.content.pm.PackageInfo
 import android.os.ParcelFileDescriptor
+import com.stevesoltys.backup.getRandomString
+import com.stevesoltys.backup.metadata.BackupMetadata
+import com.stevesoltys.backup.metadata.EncryptedBackupMetadata
+import com.stevesoltys.backup.metadata.MetadataReader
 import com.stevesoltys.backup.transport.TransportTest
 import io.mockk.Runs
 import io.mockk.every
@@ -14,6 +17,7 @@ import io.mockk.mockk
 import org.junit.jupiter.api.Assertions.*
 import org.junit.jupiter.api.Test
 import java.io.IOException
+import java.io.InputStream
 import kotlin.random.Random
 
 internal class RestoreCoordinatorTest : TransportTest() {
@@ -21,21 +25,33 @@ internal class RestoreCoordinatorTest : TransportTest() {
     private val plugin = mockk<RestorePlugin>()
     private val kv = mockk<KVRestore>()
     private val full = mockk<FullRestore>()
+    private val metadataReader = mockk<MetadataReader>()
 
-    private val restore = RestoreCoordinator(plugin, kv, full)
+    private val restore = RestoreCoordinator(plugin, kv, full, metadataReader)
 
     private val token = Random.nextLong()
+    private val inputStream = mockk<InputStream>()
     private val packageInfo2 = PackageInfo().apply { packageName = "org.example2" }
     private val packageInfoArray = arrayOf(packageInfo)
     private val packageInfoArray2 = arrayOf(packageInfo, packageInfo2)
 
     @Test
-    fun `getAvailableRestoreSets() delegates to plugin`() {
+    fun `getAvailableRestoreSets() builds set from plugin response`() {
-        val restoreSets = Array(1) { RestoreSet() }
+        val encryptedMetadata = EncryptedBackupMetadata(token, inputStream)
+        val metadata = BackupMetadata(
+                token = token,
+                androidVersion = Random.nextInt(),
+                deviceName = getRandomString())
 
-        every { plugin.getAvailableRestoreSets() } returns restoreSets
+        every { plugin.getAvailableBackups() } returns sequenceOf(encryptedMetadata, encryptedMetadata)
+        every { metadataReader.readMetadata(inputStream, token) } returns metadata
+        every { inputStream.close() } just Runs
 
-        assertEquals(restoreSets, restore.getAvailableRestoreSets())
+        val sets = restore.getAvailableRestoreSets() ?: fail()
+        assertEquals(2, sets.size)
+        assertEquals(metadata.deviceName, sets[0].device)
+        assertEquals(metadata.deviceName, sets[0].name)
+        assertEquals(metadata.token, sets[0].token)
     }
 
     @Test