From a327e56377165f3d5deb3e1fdc4a86022484897d Mon Sep 17 00:00:00 2001
From: Prem Chaitanya Prathi <chaitanyaprem@gmail.com>
Date: Wed, 3 Jan 2024 21:09:59 +0530
Subject: [PATCH] fix: return error while serializing rln metadata in case
 chainID is 0 (#985)

---
 .../protocol/rln/group_manager/dynamic/metadata.go | 11 +++++++----
 .../rln/group_manager/dynamic/metadata_test.go     | 14 ++++++++++----
 2 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/waku/v2/protocol/rln/group_manager/dynamic/metadata.go b/waku/v2/protocol/rln/group_manager/dynamic/metadata.go
index a430a810..f391fe3b 100644
--- a/waku/v2/protocol/rln/group_manager/dynamic/metadata.go
+++ b/waku/v2/protocol/rln/group_manager/dynamic/metadata.go
@@ -18,10 +18,10 @@ type RLNMetadata struct {
 }
 
 // Serialize converts a RLNMetadata into a binary format expected by zerokit's RLN
-func (r RLNMetadata) Serialize() []byte {
+func (r RLNMetadata) Serialize() ([]byte, error) {
 	chainID := r.ChainID
 	if chainID == nil {
-		chainID = big.NewInt(0)
+		return nil, errors.New("chain-id not specified and cannot be 0")
 	}
 
 	var result []byte
@@ -34,7 +34,7 @@ func (r RLNMetadata) Serialize() []byte {
 		result = binary.LittleEndian.AppendUint64(result, v.BlockNumber)
 	}
 
-	return result
+	return result, nil
 }
 
 const lastProcessedBlockOffset = 0
@@ -76,6 +76,9 @@ func DeserializeMetadata(b []byte) (RLNMetadata, error) {
 
 // SetMetadata stores some metadata into the zerokit's RLN database
 func (gm *DynamicGroupManager) SetMetadata(meta RLNMetadata) error {
-	b := meta.Serialize()
+	b, err := meta.Serialize()
+	if err != nil {
+		return err
+	}
 	return gm.rln.SetMetadata(b)
 }
diff --git a/waku/v2/protocol/rln/group_manager/dynamic/metadata_test.go b/waku/v2/protocol/rln/group_manager/dynamic/metadata_test.go
index 35c449e0..dad5eddc 100644
--- a/waku/v2/protocol/rln/group_manager/dynamic/metadata_test.go
+++ b/waku/v2/protocol/rln/group_manager/dynamic/metadata_test.go
@@ -18,8 +18,8 @@ func TestMetadata(t *testing.T) {
 		ValidRootsPerBlock: []group_manager.RootsPerBlock{{Root: [32]byte{1}, BlockNumber: 100}, {Root: [32]byte{2}, BlockNumber: 200}},
 	}
 
-	serializedMetadata := metadata.Serialize()
-
+	serializedMetadata, err := metadata.Serialize()
+	require.NoError(t, err)
 	unserializedMetadata, err := DeserializeMetadata(serializedMetadata)
 	require.NoError(t, err)
 	require.Equal(t, metadata.ChainID.Uint64(), unserializedMetadata.ChainID.Uint64())
@@ -34,8 +34,14 @@ func TestMetadata(t *testing.T) {
 	// Handle cases where the chainId is not specified (for some reason?) or no valid roots were specified
 	metadata.ChainID = nil
 	metadata.ValidRootsPerBlock = nil
-	serializedMetadata = metadata.Serialize()
+	_, err = metadata.Serialize()
+	require.Error(t, err)
+
+	metadata.ChainID = big.NewInt(1)
+	serializedMetadata, err = metadata.Serialize()
+	require.NoError(t, err)
+
 	unserializedMetadata, err = DeserializeMetadata(serializedMetadata)
 	require.NoError(t, err)
-	require.Equal(t, uint64(0), unserializedMetadata.ChainID.Uint64())
+	require.Equal(t, uint64(1), unserializedMetadata.ChainID.Uint64())
 }