From 108d01f730a2667491395a8a5ce5efb06dc4a89e Mon Sep 17 00:00:00 2001
From: Rongjian Lan <rongjian.lan@gmail.com>
Date: Mon, 2 Dec 2019 15:33:21 -0800
Subject: [PATCH] Fix cross link verification and change batch size to 50

---
 core/blockchain.go       | 21 ++++++++++-----------
 node/node_cross_shard.go |  4 ++--
 node/node_handler.go     | 15 +++++++--------
 3 files changed, 19 insertions(+), 21 deletions(-)

diff --git a/core/blockchain.go b/core/blockchain.go
index 2fafe1ced..832bbc317 100644
--- a/core/blockchain.go
+++ b/core/blockchain.go
@@ -1294,7 +1294,7 @@ func (bc *BlockChain) WriteBlockWithState(block *types.Block, receipts []*types.
 			if err := bc.WriteCrossLinks(types.CrossLinks{crossLink}); err == nil {
 				utils.Logger().Info().Uint64("blockNum", crossLink.BlockNum()).Uint32("shardID", crossLink.ShardID()).Msg("[insertChain/crosslinks] Cross Link Added to Beaconchain")
 			}
-			bc.LastContinuousCrossLink(crossLink.ShardID(), crossLink)
+			bc.LastContinuousCrossLink(crossLink)
 		}
 		//clean/update local database cache after crosslink inserted into blockchain
 		num, err := bc.DeleteCommittedFromPendingCrossLinks(*crossLinks)
@@ -2189,19 +2189,18 @@ func (bc *BlockChain) ReadCrossLink(shardID uint32, blockNum uint64) (*types.Cro
 	return crossLink, err
 }
 
-// WriteShardLastCrossLink saves the last crosslink of a shard
-func (bc *BlockChain) WriteShardLastCrossLink(shardID uint32, cl types.CrossLink) error {
-	return rawdb.WriteShardLastCrossLink(bc.db, cl.ShardID(), cl.Serialize())
-}
-
 // LastContinuousCrossLink saves the last crosslink of a shard
 // This function will update the latest crosslink in the sense that
 // any previous block's crosslink is received up to this point
 // there is no missing hole between genesis to this crosslink of given shardID
-func (bc *BlockChain) LastContinuousCrossLink(shardID uint32, cl types.CrossLink) error {
-	cl0, err := bc.ReadShardLastCrossLink(shardID)
+func (bc *BlockChain) LastContinuousCrossLink(cl types.CrossLink) error {
+	if !bc.Config().IsCrossLink(cl.Epoch()) {
+		return errors.New("Trying to write last continuous cross link with epoch before cross link starting epoch")
+	}
+
+	cl0, err := bc.ReadShardLastCrossLink(cl.ShardID())
 	if cl0 == nil {
-		bc.WriteShardLastCrossLink(shardID, cl)
+		rawdb.WriteShardLastCrossLink(bc.db, cl.ShardID(), cl.Serialize())
 		return nil
 	}
 	if err != nil {
@@ -2209,7 +2208,7 @@ func (bc *BlockChain) LastContinuousCrossLink(shardID uint32, cl types.CrossLink
 	}
 	newCheckpoint := uint64(0)
 	for i := cl0.BlockNum() + 1; i < cl.BlockNum(); i++ {
-		tmp, err := bc.ReadCrossLink(shardID, i)
+		tmp, err := bc.ReadCrossLink(cl.ShardID(), i)
 		if err != nil || tmp == nil {
 			newCheckpoint = i - 1
 			break
@@ -2221,7 +2220,7 @@ func (bc *BlockChain) LastContinuousCrossLink(shardID uint32, cl types.CrossLink
 
 	if newCheckpoint > 0 {
 		utils.Logger().Debug().Msgf("LastContinuousCrossLink: latest checkpoint blockNum %d", newCheckpoint)
-		cln, err := bc.ReadCrossLink(shardID, newCheckpoint)
+		cln, err := bc.ReadCrossLink(cl.ShardID(), newCheckpoint)
 		if err != nil {
 			return err
 		}
diff --git a/node/node_cross_shard.go b/node/node_cross_shard.go
index 71a41243d..1d946f6c7 100644
--- a/node/node_cross_shard.go
+++ b/node/node_cross_shard.go
@@ -230,8 +230,8 @@ func (node *Node) VerifyCrossLink(cl types.CrossLink) error {
 		return ctxerror.New("CrossLink BlockNumber should greater than 1")
 	}
 
-	if node.Blockchain().Config().IsCrossLink(cl.Epoch()) {
-		return ctxerror.New("CrossLink Epoch should >= crosslink epoch", "crossLinkEpoch", node.Blockchain().Config().CrossLinkEpoch)
+	if !node.Blockchain().Config().IsCrossLink(cl.Epoch()) {
+		return ctxerror.New("CrossLink Epoch should >= cross link starting epoch", "crossLinkEpoch", cl.Epoch(), "cross_link_starting_eoch", node.Blockchain().Config().CrossLinkEpoch)
 	}
 
 	// Verify signature of the new cross link header
diff --git a/node/node_handler.go b/node/node_handler.go
index a25c4ca4c..f061445a4 100644
--- a/node/node_handler.go
+++ b/node/node_handler.go
@@ -26,8 +26,7 @@ import (
 )
 
 const (
-	consensusTimeout   = 30 * time.Second
-	crossLinkBatchSize = 7
+	crossLinkBatchSize = 50
 )
 
 // receiveGroupMessage use libp2p pubsub mechanism to receive broadcast messages
@@ -218,23 +217,23 @@ func (node *Node) BroadcastCrossLink(newBlock *types.Block) {
 	if err != nil {
 		utils.Logger().Debug().Err(err).Msg("[BroadcastCrossLink] ReadShardLastCrossLink Failed")
 		header := node.Blockchain().GetHeaderByNumber(newBlock.NumberU64() - 2)
-		if header != nil {
+		if header != nil && node.Blockchain().Config().IsCrossLink(header.Epoch()) {
 			headers = append(headers, header)
 		}
 		header = node.Blockchain().GetHeaderByNumber(newBlock.NumberU64() - 1)
-		if header != nil {
+		if header != nil && node.Blockchain().Config().IsCrossLink(header.Epoch()) {
 			headers = append(headers, header)
 		}
 		headers = append(headers, newBlock.Header())
 	} else {
 		latestBlockNum = lastLink.BlockNum()
 		for blockNum := latestBlockNum + 1; blockNum <= newBlock.NumberU64(); blockNum++ {
-			if blockNum > latestBlockNum+crossLinkBatchSize {
-				break
-			}
 			header := node.Blockchain().GetHeaderByNumber(blockNum)
-			if header != nil {
+			if header != nil && node.Blockchain().Config().IsCrossLink(header.Epoch()) {
 				headers = append(headers, header)
+				if len(headers) == crossLinkBatchSize {
+					break
+				}
 			}
 		}
 	}