From 94b1cc5c34651a0ee0b3944af966daff6298b4c6 Mon Sep 17 00:00:00 2001
From: Jenita <jkawan@blinklabs.io>
Date: Mon, 29 Sep 2025 22:43:30 -0500
Subject: [PATCH] feat: added error handling for NewMsgRollForwardNtC

Signed-off-by: Jenita <jkawan@blinklabs.io>
---
 protocol/chainsync/client_test.go   | 16 +++++++----
 protocol/chainsync/messages.go      |  7 +++--
 protocol/chainsync/messages_test.go | 42 +++++++++++++----------------
 protocol/chainsync/server.go        |  8 +++---
 4 files changed, 36 insertions(+), 37 deletions(-)

diff --git a/protocol/chainsync/client_test.go b/protocol/chainsync/client_test.go
index 575ef920..5805ca63 100644
--- a/protocol/chainsync/client_test.go
+++ b/protocol/chainsync/client_test.go
@@ -207,6 +207,16 @@ func TestGetAvailableBlockRange(t *testing.T) {
 		testBlock.SlotNumber(),
 		testBlock.Hash().Bytes(),
 	)
+
+	rollForwardMsg, err := chainsync.NewMsgRollForwardNtC(
+		ledger.BlockTypeBabbage,
+		blockCbor,
+		expectedTip,
+	)
+	if err != nil {
+		t.Fatalf("failed to create RollForward message: %s", err)
+	}
+
 	conversation := append(
 		conversationHandshakeFindIntersect,
 		ouroboros_mock.ConversationEntryOutput{
@@ -235,11 +245,7 @@ func TestGetAvailableBlockRange(t *testing.T) {
 			ProtocolId: chainsync.ProtocolIdNtC,
 			IsResponse: true,
 			Messages: []protocol.Message{
-				chainsync.NewMsgRollForwardNtC(
-					ledger.BlockTypeBabbage,
-					blockCbor,
-					expectedTip,
-				),
+				rollForwardMsg,
 			},
 		},
 	)
diff --git a/protocol/chainsync/messages.go b/protocol/chainsync/messages.go
index 650d654d..708a8365 100644
--- a/protocol/chainsync/messages.go
+++ b/protocol/chainsync/messages.go
@@ -123,7 +123,7 @@ func NewMsgRollForwardNtC(
 	blockType uint,
 	blockCbor []byte,
 	tip Tip,
-) *MsgRollForwardNtC {
+) (*MsgRollForwardNtC, error) {
 	m := &MsgRollForwardNtC{
 		MessageBase: protocol.MessageBase{
 			MessageType: MessageTypeRollForward,
@@ -135,12 +135,11 @@ func NewMsgRollForwardNtC(
 	copy(m.blockCbor, blockCbor)
 	wb := NewWrappedBlock(blockType, blockCbor)
 	content, err := cbor.Encode(wb)
-	// TODO: figure out better way to handle error (#855)
 	if err != nil {
-		return nil
+		return nil, fmt.Errorf("failed to encode wrapped block: %w", err)
 	}
 	m.WrappedBlock = cbor.Tag{Number: 24, Content: content}
-	return m
+	return m, nil
 }
 
 func (m *MsgRollForwardNtC) UnmarshalCBOR(data []byte) error {
diff --git a/protocol/chainsync/messages_test.go b/protocol/chainsync/messages_test.go
index c8cea138..680e0c32 100644
--- a/protocol/chainsync/messages_test.go
+++ b/protocol/chainsync/messages_test.go
@@ -212,6 +212,15 @@ func TestMsgRollForwardNodeToNode_CorruptedCBOR(t *testing.T) {
 	}
 }
 func TestMsgRollForwardNodeToClient(t *testing.T) {
+	createMsg := func(t *testing.T, blockType uint, filePath string, tip Tip) *MsgRollForwardNtC {
+		blockData := hexDecode(string(readFile(filePath)))
+		msg, err := NewMsgRollForwardNtC(blockType, blockData, tip)
+		if err != nil {
+			t.Fatalf("failed to create NewMsgRollForwardNtC: %v", err)
+		}
+		return msg
+	}
+
 	tests := []testDefinition{
 		// Byron EBB (NtC)
 		{
@@ -220,15 +229,10 @@ func TestMsgRollForwardNodeToClient(t *testing.T) {
 					"testdata/rollforward_ntc_byron_ebb_testnet_8f8602837f7c6f8b8867dd1cbc1842cf51a27eaed2c70ef48325d00f8efb320f.hex",
 				),
 			),
-			Message: NewMsgRollForwardNtC(
+			Message: createMsg(
+				t,
 				0,
-				hexDecode(
-					string(
-						readFile(
-							"testdata/byron_ebb_testnet_8f8602837f7c6f8b8867dd1cbc1842cf51a27eaed2c70ef48325d00f8efb320f.hex",
-						),
-					),
-				),
+				"testdata/byron_ebb_testnet_8f8602837f7c6f8b8867dd1cbc1842cf51a27eaed2c70ef48325d00f8efb320f.hex",
 				Tip{
 					Point: common.Point{
 						Slot: 49055,
@@ -249,15 +253,10 @@ func TestMsgRollForwardNodeToClient(t *testing.T) {
 					"testdata/rollforward_ntc_byron_main_block_testnet_f38aa5e8cf0b47d1ffa8b2385aa2d43882282db2ffd5ac0e3dadec1a6f2ecf08.hex",
 				),
 			),
-			Message: NewMsgRollForwardNtC(
+			Message: createMsg(
+				t,
 				1,
-				hexDecode(
-					string(
-						readFile(
-							"testdata/byron_main_block_testnet_f38aa5e8cf0b47d1ffa8b2385aa2d43882282db2ffd5ac0e3dadec1a6f2ecf08.hex",
-						),
-					),
-				),
+				"testdata/byron_main_block_testnet_f38aa5e8cf0b47d1ffa8b2385aa2d43882282db2ffd5ac0e3dadec1a6f2ecf08.hex",
 				Tip{
 					Point: common.Point{
 						Slot: 49055,
@@ -278,15 +277,10 @@ func TestMsgRollForwardNodeToClient(t *testing.T) {
 					"testdata/rollforward_ntc_shelley_block_testnet_02b1c561715da9e540411123a6135ee319b02f60b9a11a603d3305556c04329f.hex",
 				),
 			),
-			Message: NewMsgRollForwardNtC(
+			Message: createMsg(
+				t,
 				2,
-				hexDecode(
-					string(
-						readFile(
-							"testdata/shelley_block_testnet_02b1c561715da9e540411123a6135ee319b02f60b9a11a603d3305556c04329f.hex",
-						),
-					),
-				),
+				"testdata/shelley_block_testnet_02b1c561715da9e540411123a6135ee319b02f60b9a11a603d3305556c04329f.hex",
 				Tip{
 					Point: common.Point{
 						Slot: 55829927,
diff --git a/protocol/chainsync/server.go b/protocol/chainsync/server.go
index fb964bfc..f7ed2880 100644
--- a/protocol/chainsync/server.go
+++ b/protocol/chainsync/server.go
@@ -137,21 +137,21 @@ func (s *Server) RollForward(blockType uint, blockData []byte, tip Tip) error {
 		}
 		return s.SendMessage(msg)
 	} else {
-		msg := NewMsgRollForwardNtC(
+		msg, err := NewMsgRollForwardNtC(
 			blockType,
 			blockData,
 			tip,
 		)
-		if msg == nil {
+		if err != nil {
 			s.Protocol.Logger().
 				Error(
-					"failed to create roll forward message",
+					fmt.Sprintf("failed to create roll forward message: %s", err),
 					"component", "network",
 					"protocol", ProtocolName,
 					"role", "server",
 					"connection_id", s.callbackContext.ConnectionId.String(),
 				)
-			return errors.New("failed to create roll forward message")
+			return fmt.Errorf("failed to create roll forward message: %w", err)
 		}
 		return s.SendMessage(msg)
 	}