EIP96 - 1. Creation of blockhash contract at Metropolis fork block. 2…

…. Updating block hashes at each block starting form Metropolis

libdevcrypto/Common.cpp

@@ -67,6 +67,8 @@ const Address dev::ZeroAddress = Address();
 
 const Address dev::MaxAddress = Address("0xffffffffffffffffffffffffffffffffffffffff");
 
+const Address dev::SuperuserAddress = Address("0xfffffffffffffffffffffffffffffffffffffffe");
+
 Public dev::toPublic(Secret const& _secret)
 {
 	auto* ctx = getCtx();

libdevcrypto/Common.h

@@ -67,6 +67,9 @@ extern const Address ZeroAddress;
 /// The last address.
 extern const Address MaxAddress;
 
+/// The SUPER_USER address.
+extern const Address SuperuserAddress;
+
 /// A vector of Ethereum addresses.
 using Addresses = h160s;
 

libethcore/Common.cpp

@@ -53,6 +53,9 @@ const unsigned c_databaseVersionModifier = 0;
 
 const unsigned c_databaseVersion = c_databaseBaseVersion + (c_databaseVersionModifier << 8) + (23 << 9);
 
+const Address c_blockhashContractAddress(0xf0);
+const bytes c_blockhashContractCode(fromHex("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"));
+
 Address toAddress(std::string const& _s)
 {
 	try

libethcore/Common.h

@@ -43,6 +43,11 @@ extern const unsigned c_minorProtocolVersion;
 /// Current database version.
 extern const unsigned c_databaseVersion;
 
+/// Address of the special contract for block hash storage defined in EIP96
+extern const Address c_blockhashContractAddress;
+/// Code of the special contract for block hash storage defined in EIP96
+extern const bytes c_blockhashContractCode;
+
 /// User-friendly string representation of the amount _b in wei.
 std::string formatBalance(bigint const& _b);
 

libethereum/Block.cpp

@@ -128,6 +128,7 @@ void Block::resetCurrent(u256 const& _timestamp)
 	m_committedToSeal = false;
 
 	performIrregularModifications();
+	updateBlockhashContract();
 }
 
 SealEngineFace* Block::sealEngine() const
@@ -692,6 +693,29 @@ void Block::performIrregularModifications()
 	}
 }
 
+void Block::updateBlockhashContract()
+{
+	u256 const blockNumber = info().number();
+
+	u256 const metropolisForkBlock = m_sealEngine->chainParams().u256Param("metropolisForkBlock");
+	if (blockNumber == metropolisForkBlock)
+	{
+		m_state.createContract(c_blockhashContractAddress);
+		m_state.setNewCode(c_blockhashContractAddress, bytes(c_blockhashContractCode));
+		m_state.commit(State::CommitBehaviour::KeepEmptyAccounts);
+	}
+
+	if (blockNumber >= metropolisForkBlock)
+	{
+		u256 const nonce = transactionsFrom(SuperuserAddress);
+		u256 const gas = 1000000;
+		Transaction tx(0, 0, gas, c_blockhashContractAddress, m_previousBlock.hash().asBytes(), nonce);
+		tx.forceSender(SuperuserAddress);
+		// passing empty lastHashes - assuming the contract doesn't use BLOCKHASH
+		m_state.execute(EnvInfo(info(), {}, 0), *m_sealEngine, tx, Permanence::Committed);
+	}
+}
+
 void Block::commitToSeal(BlockChain const& _bc, bytes const& _extraData)
 {
 	if (isSealed())

libethereum/Block.h

@@ -306,6 +306,9 @@ class Block
 	/// Performs irregular modifications right after initialization, e.g. to implement a hard fork.
 	void performIrregularModifications();
 
+	/// Creates and updates the special contract for storing block hashes according to EIP96
+	void updateBlockhashContract();
+
 	/// Provide a standard VM trace for debugging purposes.
 	std::string vmTrace(bytesConstRef _block, BlockChain const& _bc, ImportRequirements::value _ir);