sanitize filename before creating it in the blob dir

src/org/thoughtcrime/securesms/connect/DcHelper.java

@@ -31,6 +31,7 @@ import org.thoughtcrime.securesms.database.model.ThreadRecord;
 import org.thoughtcrime.securesms.notifications.NotificationCenter;
 import org.thoughtcrime.securesms.providers.PersistentBlobProvider;
 import org.thoughtcrime.securesms.recipients.Recipient;
+import org.thoughtcrime.securesms.util.FileUtils;
 import org.thoughtcrime.securesms.util.MediaUtil;
 
 import java.io.File;
@@ -356,6 +357,8 @@ public class DcHelper {
   }
 
   public static String getBlobdirFile(DcContext dcContext, String filename, String ext) {
+    filename = FileUtils.sanitizeFilename(filename);
+    ext = FileUtils.sanitizeFilename(ext);
     String outPath = null;
     for (int i = 0; i < 1000; i++) {
       String test = dcContext.getBlobdir() + "/" + filename + (i == 0 ? "" : i < 100 ? "-" + i : "-" + (new Date().getTime() + i)) + ext;

src/org/thoughtcrime/securesms/util/FileUtils.java

@@ -1,9 +1,49 @@
 package org.thoughtcrime.securesms.util;
 
+import android.text.TextUtils;
+
 import java.io.FileDescriptor;
+import java.nio.charset.StandardCharsets;
 
 public class FileUtils {
 
   public static native int getFileDescriptorOwner(FileDescriptor fileDescriptor);
 
+  public static String sanitizeFilename(String name) {
+    if (TextUtils.isEmpty(name) || ".".equals(name) || "..".equals(name)) {
+      return "(invalid)";
+    }
+    final StringBuilder res = new StringBuilder(name.length());
+    for (int i = 0; i < name.length(); i++) {
+      final char c = name.charAt(i);
+      if (isValidFilenameChar(c)) {
+        res.append(c);
+      } else {
+        res.append('_');
+      }
+    }
+    return res.toString();
+  }
+
+  private static boolean isValidFilenameChar(char c) {
+    if ((0x00 <= c && c <= 0x1f)) {
+      return false;
+    }
+    switch (c) {
+      case '"':
+      case '*':
+      case '/':
+      case ':':
+      case '<':
+      case '>':
+      case '?':
+      case '\\':
+      case '\0':
+      case '|':
+      case 0x7F:
+        return false;
+      default:
+        return true;
+    }
+  }
 }