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-rw-r--r--core/blockchain.go20
-rw-r--r--tests/init.go3
2 files changed, 17 insertions, 6 deletions
diff --git a/core/blockchain.go b/core/blockchain.go
index 22dd617ad..2c6ff24f9 100644
--- a/core/blockchain.go
+++ b/core/blockchain.go
@@ -725,14 +725,18 @@ func (self *BlockChain) writeHeader(header *types.Header) error {
if ptd == nil {
return ParentError(header.ParentHash)
}
- td := new(big.Int).Add(header.Difficulty, ptd)
+
+ localTd := self.GetTd(self.currentHeader.Hash())
+ externTd := new(big.Int).Add(header.Difficulty, ptd)
// Make sure no inconsistent state is leaked during insertion
self.mu.Lock()
defer self.mu.Unlock()
// If the total difficulty is higher than our known, add it to the canonical chain
- if td.Cmp(self.GetTd(self.currentHeader.Hash())) > 0 {
+ // Second clause in the if statement reduces the vulnerability to selfish mining.
+ // Please refer to http://www.cs.cornell.edu/~ie53/publications/btcProcFC.pdf
+ if externTd.Cmp(localTd) > 0 || (externTd.Cmp(localTd) == 0 && mrand.Float64() < 0.5) {
// Delete any canonical number assignments above the new head
for i := header.Number.Uint64() + 1; GetCanonicalHash(self.chainDb, i) != (common.Hash{}); i++ {
DeleteCanonicalHash(self.chainDb, i)
@@ -753,7 +757,7 @@ func (self *BlockChain) writeHeader(header *types.Header) error {
self.currentHeader = types.CopyHeader(header)
}
// Irrelevant of the canonical status, write the header itself to the database
- if err := WriteTd(self.chainDb, header.Hash(), td); err != nil {
+ if err := WriteTd(self.chainDb, header.Hash(), externTd); err != nil {
glog.Fatalf("failed to write header total difficulty: %v", err)
}
if err := WriteHeader(self.chainDb, header); err != nil {
@@ -1060,14 +1064,18 @@ func (self *BlockChain) WriteBlock(block *types.Block) (status writeStatus, err
if ptd == nil {
return NonStatTy, ParentError(block.ParentHash())
}
- td := new(big.Int).Add(block.Difficulty(), ptd)
+
+ localTd := self.GetTd(self.currentBlock.Hash())
+ externTd := new(big.Int).Add(block.Difficulty(), ptd)
// Make sure no inconsistent state is leaked during insertion
self.mu.Lock()
defer self.mu.Unlock()
// If the total difficulty is higher than our known, add it to the canonical chain
- if td.Cmp(self.GetTd(self.currentBlock.Hash())) > 0 {
+ // Second clause in the if statement reduces the vulnerability to selfish mining.
+ // Please refer to http://www.cs.cornell.edu/~ie53/publications/btcProcFC.pdf
+ if externTd.Cmp(localTd) > 0 || (externTd.Cmp(localTd) == 0 && mrand.Float64() < 0.5) {
// Reorganize the chain if the parent is not the head block
if block.ParentHash() != self.currentBlock.Hash() {
if err := self.reorg(self.currentBlock, block); err != nil {
@@ -1081,7 +1089,7 @@ func (self *BlockChain) WriteBlock(block *types.Block) (status writeStatus, err
status = SideStatTy
}
// Irrelevant of the canonical status, write the block itself to the database
- if err := WriteTd(self.chainDb, block.Hash(), td); err != nil {
+ if err := WriteTd(self.chainDb, block.Hash(), externTd); err != nil {
glog.Fatalf("failed to write block total difficulty: %v", err)
}
if err := WriteBlock(self.chainDb, block); err != nil {
diff --git a/tests/init.go b/tests/init.go
index a86970499..caa4eca6c 100644
--- a/tests/init.go
+++ b/tests/init.go
@@ -44,6 +44,9 @@ var (
"TRANSCT__RandomByteAtTheEnd",
"BLOCK__ZeroByteAtTheEnd",
"TRANSCT__ZeroByteAtTheEnd",
+
+ "ChainAtoChainB_blockorder2",
+ "ChainAtoChainB_blockorder1",
}
/* Go client does not support transaction (account) nonces above 2^64. This