Reject invalid sized NodeIds.

1 files changed, 10 insertions, 1 deletions

diff --git a/Mainline.hs b/Mainline.hs
index 0f6d7f16..5180352a 100644
--- a/Mainline.hs
+++ b/Mainline.hs
@@ -79,7 +79,16 @@ import qualified Data.Aeson as JSON
 import Text.Read
 
 newtype NodeId = NodeId ByteString
- deriving (Eq,Ord,ByteArrayAccess, BEncode, Bits, Hashable)
+ deriving (Eq,Ord,ByteArrayAccess, Bits, Hashable)
+
+instance BEncode NodeId where
+    fromBEncode bval = do
+        bs <- fromBEncode bval
+        if B.length bs /= 20
+            then Left "Invalid length node id."
+            else Right $ NodeId bs
+
+    toBEncode (NodeId bs) = toBEncode bs
 
 instance Show NodeId where
     show (NodeId bs) = Char8.unpack $ Base16.encode bs