add explicit error message for outdated backup files

src/conversations/java/eu/siacs/conversations/ui/ImportBackupActivity.java

@@ -30,6 +30,7 @@ import eu.siacs.conversations.databinding.DialogEnterPasswordBinding;
 import eu.siacs.conversations.services.ImportBackupService;
 import eu.siacs.conversations.ui.adapter.BackupFileAdapter;
 import eu.siacs.conversations.ui.util.SettingsUtils;
+import eu.siacs.conversations.utils.BackupFileHeader;
 import eu.siacs.conversations.utils.ThemeHelper;
 
 public class ImportBackupActivity extends ActionBarActivity implements ServiceConnection, ImportBackupService.OnBackupFilesLoaded, BackupFileAdapter.OnItemClickedListener, ImportBackupService.OnBackupProcessed {
@@ -131,6 +132,8 @@ public class ImportBackupActivity extends ActionBarActivity implements ServiceCo
         try {
             final ImportBackupService.BackupFile backupFile = ImportBackupService.BackupFile.read(this, uri);
             showEnterPasswordDialog(backupFile, finishOnCancel);
+        } catch (final BackupFileHeader.OutdatedBackupFileVersion e) {
+            Snackbar.make(binding.coordinator, R.string.outdated_backup_file_format, Snackbar.LENGTH_LONG).show();
         } catch (final IOException | IllegalArgumentException e) {
             Log.d(Config.LOGTAG, "unable to open backup file " + uri, e);
             Snackbar.make(binding.coordinator, R.string.not_a_backup_file, Snackbar.LENGTH_LONG).show();

src/main/java/eu/siacs/conversations/utils/BackupFileHeader.java

@@ -50,17 +50,19 @@ public class BackupFileHeader {
 
     public static BackupFileHeader read(DataInputStream inputStream) throws IOException {
         final int version = inputStream.readInt();
+        final String app = inputStream.readUTF();
+        final String jid = inputStream.readUTF();
+        long timestamp = inputStream.readLong();
+        final byte[] iv = new byte[12];
+        inputStream.readFully(iv);
+        final byte[] salt = new byte[16];
+        inputStream.readFully(salt);
+        if (version < VERSION) {
+            throw new OutdatedBackupFileVersion();
+        }
         if (version != VERSION) {
             throw new IllegalArgumentException("Backup File version was " + version + " but app only supports version " + VERSION);
         }
-        String app = inputStream.readUTF();
-        String jid = inputStream.readUTF();
-        long timestamp = inputStream.readLong();
-        byte[] iv = new byte[12];
-        inputStream.readFully(iv);
-        byte[] salt = new byte[16];
-        inputStream.readFully(salt);
-
         return new BackupFileHeader(app, Jid.of(jid), timestamp, iv, salt);
 
     }
@@ -84,4 +86,8 @@ public class BackupFileHeader {
     public long getTimestamp() {
         return timestamp;
     }
+
+    public static class OutdatedBackupFileVersion extends RuntimeException {
+
+    }
 }

src/main/res/values/strings.xml

@@ -894,6 +894,7 @@
     <string name="event">Event</string>
     <string name="open_backup">Open backup</string>
     <string name="not_a_backup_file">The file you selected is not a Conversations backup file</string>
+    <string name="outdated_backup_file_format">You are trying to import an outdated backup file format</string>
     <string name="account_already_setup">This account has already been setup</string>
     <string name="please_enter_password">Please enter the password for this account</string>
     <string name="unable_to_perform_this_action">Could not perform this action</string>