From f1f0e7d0b962c802124b2ed9123d3e9bd9cd9644 Mon Sep 17 00:00:00 2001
From: Wei-Ning Huang <w@dexon.org>
Date: Fri, 16 Nov 2018 17:26:50 +0800
Subject: core: fix light node synchronization issue (#30)

InsertChain() need to record the correct roundHeight mapping in order to
process snapshotRoundHeight() governance method correctly.
---
 core/blockchain.go     |  1 +
 core/vm/evm.go         |  3 +++
 core/vm/governance.go  | 20 +++++++++++---------
 core/vm/interpreter.go |  3 +++
 dex/backend.go         |  1 +
 dex/handler.go         |  4 ++++
 6 files changed, 23 insertions(+), 9 deletions(-)

diff --git a/core/blockchain.go b/core/blockchain.go
index 344a032a1..f8d9bca9e 100644
--- a/core/blockchain.go
+++ b/core/blockchain.go
@@ -1379,6 +1379,7 @@ func (bc *BlockChain) insertChain(chain types.Blocks, verifySeals bool) (int, []
 				"txs", len(block.Transactions()), "gas", block.GasUsed(), "uncles", len(block.Uncles()),
 				"root", block.Root())
 			events = append(events, ChainSideEvent{block})
+			panic("fork found")
 		}
 		blockInsertTimer.UpdateSince(start)
 		stats.processed++
diff --git a/core/vm/evm.go b/core/vm/evm.go
index 865ab0d5b..64f71e530 100644
--- a/core/vm/evm.go
+++ b/core/vm/evm.go
@@ -479,3 +479,6 @@ func (evm *EVM) Create2(caller ContractRef, code []byte, gas uint64, endowment *
 
 // ChainConfig returns the environment's chain configuration
 func (evm *EVM) ChainConfig() *params.ChainConfig { return evm.chainConfig }
+
+// IsBlockProposer returns whether or not we are a block proposer.
+func (evm *EVM) IsBlockProposer() bool { return evm.vmConfig.IsBlockProposer }
diff --git a/core/vm/governance.go b/core/vm/governance.go
index b38733e1a..f406294d2 100644
--- a/core/vm/governance.go
+++ b/core/vm/governance.go
@@ -1767,16 +1767,18 @@ func (g *GovernanceContract) transferOwnership(newOwner common.Address) ([]byte,
 }
 
 func (g *GovernanceContract) snapshotRound(round, height *big.Int) ([]byte, error) {
-	// Validate if this mapping is correct.
-	realHeight, ok := g.evm.Context.GetRoundHeight(round.Uint64())
-	if !ok {
-		g.penalize()
-		return nil, errExecutionReverted
-	}
+	// Validate if this mapping is correct. Only block proposer need to verify this.
+	if g.evm.IsBlockProposer() {
+		realHeight, ok := g.evm.Context.GetRoundHeight(round.Uint64())
+		if !ok {
+			g.penalize()
+			return nil, errExecutionReverted
+		}
 
-	if height.Cmp(new(big.Int).SetUint64(realHeight)) != 0 {
-		g.penalize()
-		return nil, errExecutionReverted
+		if height.Cmp(new(big.Int).SetUint64(realHeight)) != 0 {
+			g.penalize()
+			return nil, errExecutionReverted
+		}
 	}
 
 	// Only allow updating the next round.
diff --git a/core/vm/interpreter.go b/core/vm/interpreter.go
index b5e35f1a4..ffe5ff626 100644
--- a/core/vm/interpreter.go
+++ b/core/vm/interpreter.go
@@ -46,6 +46,9 @@ type Config struct {
 	EWASMInterpreter string
 	// Type of the EVM interpreter
 	EVMInterpreter string
+
+	// Whether or not we are a block proposer.
+	IsBlockProposer bool
 }
 
 // Interpreter is used to run Ethereum based contracts and will utilise the
diff --git a/dex/backend.go b/dex/backend.go
index 740b8cd6f..07646fd76 100644
--- a/dex/backend.go
+++ b/dex/backend.go
@@ -131,6 +131,7 @@ func New(ctx *node.ServiceContext, config *Config) (*Dexon, error) {
 			EnablePreimageRecording: config.EnablePreimageRecording,
 			EWASMInterpreter:        config.EWASMInterpreter,
 			EVMInterpreter:          config.EVMInterpreter,
+			IsBlockProposer:         config.BlockProposerEnabled,
 		}
 		cacheConfig = &core.CacheConfig{Disabled: config.NoPruning, TrieCleanLimit: config.TrieCleanCache, TrieDirtyLimit: config.TrieDirtyCache, TrieTimeLimit: config.TrieTimeout}
 	)
diff --git a/dex/handler.go b/dex/handler.go
index 7bc9c297d..21322e4e0 100644
--- a/dex/handler.go
+++ b/dex/handler.go
@@ -1079,6 +1079,10 @@ func (pm *ProtocolManager) peerSetLoop() {
 			pm.BroadcastBlock(event.Block, true)  // First propagate block to peers
 			pm.BroadcastBlock(event.Block, false) // Only then announce to the rest
 
+			if !pm.isBlockProposer {
+				break
+			}
+
 			newRound := pm.gov.LenCRS() - 1
 			log.Trace("new round", "round", newRound)
 			if newRound == round {
-- 
cgit v1.2.3