properly check for gnd files

1 files changed, 9 insertions, 3 deletions

diff --git a/src/fs/fs_directory.c b/src/fs/fs_directory.c
index 03065958e..6698ad010 100644
--- a/src/fs/fs_directory.c
+++ b/src/fs/fs_directory.c
@@ -201,10 +201,16 @@ GNUNET_FS_directory_list_contents (size_t size,
   struct GNUNET_CONTAINER_MetaData *md;
   char *filename;
 
+  if ( (offset == 0) &&
+       ( (size < 8 + sizeof (uint32_t)) ||
+         (0 != memcmp (cdata, GNUNET_FS_DIRECTORY_MAGIC, 8)) ) )
+    {
+      GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                  _("MAGIC mismatch.  This is not a GNUnet directory.\n"));
+      return GNUNET_SYSERR;
+    }
   pos = offset;
-  if ( (pos == 0) && 
-       (size >= 8 + sizeof (uint32_t)) &&
-       (0 == memcmp (cdata, GNUNET_FS_DIRECTORY_MAGIC, 8)) )
+  if (offset == 0) 
     {
       memcpy (&mdSize, &cdata[8], sizeof (uint32_t));
       mdSize = ntohl (mdSize);