core: fix light node synchronization issue (#30)

InsertChain() need to record the correct roundHeight mapping in order to
process snapshotRoundHeight() governance method correctly.

4 files changed, 18 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