Merge branch 'master' into check-updates

2016-11-18 11:45:04 +08:00
parent 2fa2f8342a b79d65c0f3
commit 28aabcdb6c
168 changed files with 11973 additions and 8352 deletions
--- a/ethcore/res/authority_round.json
+++ b/ethcore/res/authority_round.json
@@ -0,0 +1,42 @@
+{
+	"name": "TestAuthorityRound",
+	"engine": {
+		"AuthorityRound": {
+			"params": {
+				"gasLimitBoundDivisor": "0x0400",
+				"stepDuration": "1",
+				"authorities" : [
+					"0x7d577a597b2742b498cb5cf0c26cdcd726d39e6e",
+					"0x82a978b3f5962a5b0957d9ee9eef472ee55b42f1"
+				]
+			}
+		}
+	},
+	"params": {
+		"accountStartNonce": "0x0",
+		"maximumExtraDataSize": "0x20",
+		"minGasLimit": "0x1388",
+		"networkID" : "0x69"
+	},
+	"genesis": {
+		"seal": {
+			"generic": {
+				"fields": 1,
+				"rlp": "0x11bbe8db4e347b4e8c937c1c8370e4b5ed33adb3db69cbdb7a38e1e50b1b82fa"
+			}
+		},
+		"difficulty": "0x20000",
+		"author": "0x0000000000000000000000000000000000000000",
+		"timestamp": "0x00",
+		"parentHash": "0x0000000000000000000000000000000000000000000000000000000000000000",
+		"extraData": "0x",
+		"gasLimit": "0x2fefd8"
+	},
+	"accounts": {
+		"0000000000000000000000000000000000000001": { "balance": "1", "nonce": "1048576", "builtin": { "name": "ecrecover", "pricing": { "linear": { "base": 3000, "word": 0 } } } },
+		"0000000000000000000000000000000000000002": { "balance": "1", "nonce": "1048576", "builtin": { "name": "sha256", "pricing": { "linear": { "base": 60, "word": 12 } } } },
+		"0000000000000000000000000000000000000003": { "balance": "1", "nonce": "1048576", "builtin": { "name": "ripemd160", "pricing": { "linear": { "base": 600, "word": 120 } } } },
+		"0000000000000000000000000000000000000004": { "balance": "1", "nonce": "1048576", "builtin": { "name": "identity", "pricing": { "linear": { "base": 15, "word": 3 } } } },
+		"9cce34f7ab185c7aba1b7c8140d620b4bda941d6": { "balance": "1606938044258990275541962092341162602522202993782792835301376", "nonce": "1048576" }
+	}
+}
--- a/ethcore/res/basic_authority.json
+++ b/ethcore/res/basic_authority.json
@@ -1,5 +1,5 @@
 {
-	"name": "TestAuthority",
+	"name": "TestBasicAuthority",
 	"engine": {
 		"BasicAuthority": {
 			"params": {
--- a/ethcore/res/ethereum/frontier.json
+++ b/ethcore/res/ethereum/frontier.json
@@ -131,10 +131,11 @@
 					"0x807640a13483f8ac783c557fcdf27be11ea4ac7a"
 				],
 				"eip150Transition": "0x259518",
-				"eip155Transition": "0x7fffffffffffffff",
-				"eip160Transition": "0x7fffffffffffffff",
-				"eip161abcTransition": "0x7fffffffffffffff",
-				"eip161dTransition": "0x7fffffffffffffff"
+				"eip155Transition": 2675000,
+				"eip160Transition": 2675000,
+				"eip161abcTransition": 2675000,
+				"eip161dTransition": 2675000,
+				"maxCodeSize": 24576
 			}
 		}
 	},
--- a/ethcore/res/ethereum/morden.json
+++ b/ethcore/res/ethereum/morden.json
@@ -11,10 +11,10 @@
 				"registrar": "0x52dff57a8a1532e6afb3dc07e2af58bb9eb05b3d",
 				"homesteadTransition": "0x789b0",
 				"eip150Transition": "0x1b34d8",
-				"eip155Transition": "0x7fffffffffffffff",
-				"eip160Transition": "0x7fffffffffffffff",
-				"eip161abcTransition": "0x7fffffffffffffff",
-				"eip161dTransition": "0x7fffffffffffffff"
+				"eip155Transition": 1885000,
+				"eip160Transition": 1885000,
+				"eip161abcTransition": 1885000,
+				"eip161dTransition": 1885000
 			}
 		}
 	},
--- a/ethcore/res/instant_seal.json
+++ b/ethcore/res/instant_seal.json
@@ -1,5 +1,5 @@
 {
-	"name": "TestInstantSeal",
+	"name": "DevelopmentChain",
 	"engine": {
 		"InstantSeal": null
 	},
@@ -28,6 +28,6 @@
 		"0000000000000000000000000000000000000002": { "balance": "1", "nonce": "1048576", "builtin": { "name": "sha256", "pricing": { "linear": { "base": 60, "word": 12 } } } },
 		"0000000000000000000000000000000000000003": { "balance": "1", "nonce": "1048576", "builtin": { "name": "ripemd160", "pricing": { "linear": { "base": 600, "word": 120 } } } },
 		"0000000000000000000000000000000000000004": { "balance": "1", "nonce": "1048576", "builtin": { "name": "identity", "pricing": { "linear": { "base": 15, "word": 3 } } } },
-		"102e61f5d8f9bc71d0ad4a084df4e65e05ce0e1c": { "balance": "1606938044258990275541962092341162602522202993782792835301376", "nonce": "1048576" }
+		"0x00a329c0648769a73afac7f9381e08fb43dbea72": { "balance": "1606938044258990275541962092341162602522202993782792835301376", "nonce": "1048576" }
 	}
 }
--- a/ethcore/src/client/client.rs
+++ b/ethcore/src/client/client.rs
@@ -556,6 +556,7 @@ impl Client {

 	/// Import transactions from the IO queue
 	pub fn import_queued_transactions(&self, transactions: &[Bytes]) -> usize {
+		trace!(target: "external_tx", "Importing queued");
 		let _timer = PerfTimer::new("import_queued_transactions");
 		self.queue_transactions.fetch_sub(transactions.len(), AtomicOrdering::SeqCst);
 		let txs = transactions.iter().filter_map(|bytes| UntrustedRlp::new(bytes).as_val().ok()).collect();
@@ -563,6 +564,11 @@ impl Client {
 		results.len()
 	}

+	/// Used by PoA to try sealing on period change.
+	pub fn update_sealing(&self) {
+		self.miner.update_sealing(self)
+	}
+
 	/// Attempt to get a copy of a specific block's final state.
 	///
 	/// This will not fail if given BlockID::Latest.
@@ -1254,7 +1260,9 @@ impl BlockChainClient for Client {
 	}

 	fn queue_transactions(&self, transactions: Vec<Bytes>) {
-		if self.queue_transactions.load(AtomicOrdering::Relaxed) > MAX_TX_QUEUE_SIZE {
+		let queue_size = self.queue_transactions.load(AtomicOrdering::Relaxed);
+		trace!(target: "external_tx", "Queue size: {}", queue_size);
+		if queue_size > MAX_TX_QUEUE_SIZE {
 			debug!("Ignoring {} transactions: queue is full", transactions.len());
 		} else {
 			let len = transactions.len();
--- a/ethcore/src/client/test_client.rs
+++ b/ethcore/src/client/test_client.rs
@@ -119,6 +119,16 @@ impl TestBlockChainClient {
 	/// Creates new test client with specified extra data for each block
 	pub fn new_with_extra_data(extra_data: Bytes) -> Self {
 		let spec = Spec::new_test();
+		TestBlockChainClient::new_with_spec_and_extra(spec, extra_data)
+	}
+
+	/// Create test client with custom spec.
+	pub fn new_with_spec(spec: Spec) -> Self {
+		TestBlockChainClient::new_with_spec_and_extra(spec, Bytes::new())
+	}
+
+	/// Create test client with custom spec and extra data.
+	pub fn new_with_spec_and_extra(spec: Spec, extra_data: Bytes) -> Self {
 		let mut client = TestBlockChainClient {
 			blocks: RwLock::new(HashMap::new()),
 			numbers: RwLock::new(HashMap::new()),
@@ -315,7 +325,7 @@ pub fn get_temp_state_db() -> GuardedTempResult<StateDB> {

 impl MiningBlockChainClient for TestBlockChainClient {
 	fn latest_schedule(&self) -> Schedule {
-		Schedule::new_post_eip150(true, true, true)
+		Schedule::new_post_eip150(24576, true, true, true)
 	}

 	fn prepare_open_block(&self, author: Address, gas_range_target: (U256, U256), extra_data: Bytes) -> OpenBlock {
--- a/ethcore/src/engines/authority_round.rs
+++ b/ethcore/src/engines/authority_round.rs
@@ -0,0 +1,429 @@
+// Copyright 2015, 2016 Ethcore (UK) Ltd.
+// This file is part of Parity.
+
+// Parity is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Parity is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Parity.  If not, see <http://www.gnu.org/licenses/>.
+
+//! A blockchain engine that supports a non-instant BFT proof-of-authority.
+
+use std::sync::atomic::{AtomicUsize, AtomicBool, Ordering as AtomicOrdering};
+use std::sync::Weak;
+use std::time::{UNIX_EPOCH, Duration};
+use util::*;
+use ethkey::{verify_address, Signature};
+use rlp::{UntrustedRlp, View, encode};
+use account_provider::AccountProvider;
+use block::*;
+use spec::CommonParams;
+use engines::Engine;
+use header::Header;
+use error::{Error, BlockError};
+use evm::Schedule;
+use ethjson;
+use io::{IoContext, IoHandler, TimerToken, IoService, IoChannel};
+use service::ClientIoMessage;
+use transaction::SignedTransaction;
+use env_info::EnvInfo;
+use builtin::Builtin;
+
+/// `AuthorityRound` params.
+#[derive(Debug, PartialEq)]
+pub struct AuthorityRoundParams {
+	/// Gas limit divisor.
+	pub gas_limit_bound_divisor: U256,
+	/// Time to wait before next block or authority switching.
+	pub step_duration: Duration,
+	/// Valid authorities.
+	pub authorities: Vec<Address>,
+	/// Number of authorities.
+	pub authority_n: usize,
+}
+
+impl From<ethjson::spec::AuthorityRoundParams> for AuthorityRoundParams {
+	fn from(p: ethjson::spec::AuthorityRoundParams) -> Self {
+		AuthorityRoundParams {
+			gas_limit_bound_divisor: p.gas_limit_bound_divisor.into(),
+			step_duration: Duration::from_secs(p.step_duration.into()),
+			authority_n: p.authorities.len(),
+			authorities: p.authorities.into_iter().map(Into::into).collect::<Vec<_>>(),
+		}
+	}
+}
+
+/// Engine using `AuthorityRound` proof-of-work consensus algorithm, suitable for Ethereum
+/// mainnet chains in the Olympic, Frontier and Homestead eras.
+pub struct AuthorityRound {
+	params: CommonParams,
+	our_params: AuthorityRoundParams,
+	builtins: BTreeMap<Address, Builtin>,
+	transition_service: IoService<BlockArrived>,
+	message_channel: Mutex<Option<IoChannel<ClientIoMessage>>>,
+	step: AtomicUsize,
+	proposed: AtomicBool,
+}
+
+fn header_step(header: &Header) -> Result<usize, ::rlp::DecoderError> {
+	UntrustedRlp::new(&header.seal()[0]).as_val()
+}
+
+fn header_signature(header: &Header) -> Result<Signature, ::rlp::DecoderError> {
+	UntrustedRlp::new(&header.seal()[1]).as_val::<H520>().map(Into::into)
+}
+
+trait AsMillis {
+	fn as_millis(&self) -> u64;
+}
+
+impl AsMillis for Duration {
+	fn as_millis(&self) -> u64 {
+		self.as_secs()*1_000 + (self.subsec_nanos()/1_000_000) as u64
+	}
+}
+
+impl AuthorityRound {
+	/// Create a new instance of AuthorityRound engine.
+	pub fn new(params: CommonParams, our_params: AuthorityRoundParams, builtins: BTreeMap<Address, Builtin>) -> Result<Arc<Self>, Error> {
+		let initial_step = (unix_now().as_secs() / our_params.step_duration.as_secs()) as usize;
+		let engine = Arc::new(
+			AuthorityRound {
+				params: params,
+				our_params: our_params,
+				builtins: builtins,
+				transition_service: try!(IoService::<BlockArrived>::start()),
+				message_channel: Mutex::new(None),
+				step: AtomicUsize::new(initial_step),
+				proposed: AtomicBool::new(false)
+			});
+		let handler = TransitionHandler { engine: Arc::downgrade(&engine) };
+		try!(engine.transition_service.register_handler(Arc::new(handler)));
+		Ok(engine)
+	}
+
+	fn step(&self) -> usize {
+		self.step.load(AtomicOrdering::SeqCst)
+	}
+
+	fn remaining_step_duration(&self) -> Duration {
+		let now = unix_now();
+		let step_end = self.our_params.step_duration * (self.step() as u32 + 1);
+		if step_end > now {
+			step_end - now
+		} else {
+			Duration::from_secs(0)
+		}
+	}
+
+	fn step_proposer(&self, step: usize) -> &Address {
+		let ref p = self.our_params;
+		p.authorities.get(step % p.authority_n).expect("There are authority_n authorities; taking number modulo authority_n gives number in authority_n range; qed")
+	}
+
+	fn is_step_proposer(&self, step: usize, address: &Address) -> bool {
+		self.step_proposer(step) == address
+	}
+}
+
+fn unix_now() -> Duration {
+	UNIX_EPOCH.elapsed().expect("Valid time has to be set in your system.")
+}
+
+struct TransitionHandler {
+	engine: Weak<AuthorityRound>,
+}
+
+#[derive(Clone)]
+struct BlockArrived;
+
+const ENGINE_TIMEOUT_TOKEN: TimerToken = 23;
+
+impl IoHandler<BlockArrived> for TransitionHandler {
+	fn initialize(&self, io: &IoContext<BlockArrived>) {
+		if let Some(engine) = self.engine.upgrade() {
+			io.register_timer_once(ENGINE_TIMEOUT_TOKEN, engine.remaining_step_duration().as_millis())
+				.unwrap_or_else(|e| warn!(target: "poa", "Failed to start consensus step timer: {}.", e))
+		}
+	}
+
+	fn timeout(&self, io: &IoContext<BlockArrived>, timer: TimerToken) {
+		if timer == ENGINE_TIMEOUT_TOKEN {
+			if let Some(engine) = self.engine.upgrade() {
+				engine.step.fetch_add(1, AtomicOrdering::SeqCst);
+				engine.proposed.store(false, AtomicOrdering::SeqCst);
+				if let Some(ref channel) = *engine.message_channel.lock() {
+					match channel.send(ClientIoMessage::UpdateSealing) {
+						Ok(_) => trace!(target: "poa", "timeout: UpdateSealing message sent for step {}.", engine.step.load(AtomicOrdering::Relaxed)),
+						Err(err) => trace!(target: "poa", "timeout: Could not send a sealing message {} for step {}.", err, engine.step.load(AtomicOrdering::Relaxed)),
+					}
+				}
+				io.register_timer_once(ENGINE_TIMEOUT_TOKEN, engine.remaining_step_duration().as_millis())
+					.unwrap_or_else(|e| warn!(target: "poa", "Failed to restart consensus step timer: {}.", e))
+			}
+		}
+	}
+}
+
+impl Engine for AuthorityRound {
+	fn name(&self) -> &str { "AuthorityRound" }
+	fn version(&self) -> SemanticVersion { SemanticVersion::new(1, 0, 0) }
+	/// Two fields - consensus step and the corresponding proposer signature.
+	fn seal_fields(&self) -> usize { 2 }
+
+	fn params(&self) -> &CommonParams { &self.params }
+	fn builtins(&self) -> &BTreeMap<Address, Builtin> { &self.builtins }
+
+	/// Additional engine-specific information for the user/developer concerning `header`.
+	fn extra_info(&self, header: &Header) -> BTreeMap<String, String> {
+		map![
+			"step".into() => header_step(header).as_ref().map(ToString::to_string).unwrap_or("".into()),
+			"signature".into() => header_signature(header).as_ref().map(ToString::to_string).unwrap_or("".into())
+		]
+	}
+
+	fn schedule(&self, _env_info: &EnvInfo) -> Schedule {
+		Schedule::new_post_eip150(usize::max_value(), true, true, true)
+	}
+
+	fn populate_from_parent(&self, header: &mut Header, parent: &Header, gas_floor_target: U256, _gas_ceil_target: U256) {
+		header.set_difficulty(parent.difficulty().clone());
+		header.set_gas_limit({
+			let gas_limit = parent.gas_limit().clone();
+			let bound_divisor = self.our_params.gas_limit_bound_divisor;
+			if gas_limit < gas_floor_target {
+				min(gas_floor_target, gas_limit + gas_limit / bound_divisor - 1.into())
+			} else {
+				max(gas_floor_target, gas_limit - gas_limit / bound_divisor + 1.into())
+			}
+		});
+	}
+
+	/// Apply the block reward on finalisation of the block.
+	/// This assumes that all uncles are valid uncles (i.e. of at least one generation before the current).
+	fn on_close_block(&self, _block: &mut ExecutedBlock) {}
+
+	fn is_sealer(&self, author: &Address) -> Option<bool> {
+		let ref p = self.our_params;
+		Some(p.authorities.contains(author))
+	}
+
+	/// Attempt to seal the block internally.
+	///
+	/// This operation is synchronous and may (quite reasonably) not be available, in which `false` will
+	/// be returned.
+	fn generate_seal(&self, block: &ExecutedBlock, accounts: Option<&AccountProvider>) -> Option<Vec<Bytes>> {
+		if self.proposed.load(AtomicOrdering::SeqCst) { return None; }
+		let header = block.header();
+		let step = self.step();
+		if self.is_step_proposer(step, header.author()) {
+			if let Some(ap) = accounts {
+				// Account should be permanently unlocked, otherwise sealing will fail.
+				if let Ok(signature) = ap.sign(*header.author(), None, header.bare_hash()) {
+					trace!(target: "poa", "generate_seal: Issuing a block for step {}.", step);
+					self.proposed.store(true, AtomicOrdering::SeqCst);
+					return Some(vec![encode(&step).to_vec(), encode(&(&*signature as &[u8])).to_vec()]);
+				} else {
+					warn!(target: "poa", "generate_seal: FAIL: Accounts secret key unavailable.");
+				}
+			} else {
+				warn!(target: "poa", "generate_seal: FAIL: Accounts not provided.");
+			}
+		}
+		None
+	}
+
+	/// Check the number of seal fields.
+	fn verify_block_basic(&self, header: &Header, _block: Option<&[u8]>) -> Result<(), Error> {
+		if header.seal().len() != self.seal_fields() {
+			trace!(target: "poa", "verify_block_basic: wrong number of seal fields");
+			Err(From::from(BlockError::InvalidSealArity(
+				Mismatch { expected: self.seal_fields(), found: header.seal().len() }
+			)))
+		} else {
+			Ok(())
+		}
+	}
+
+	/// Check if the signature belongs to the correct proposer.
+	fn verify_block_unordered(&self, header: &Header, _block: Option<&[u8]>) -> Result<(), Error> {
+        let header_step = try!(header_step(header));
+        // Give one step slack if step is lagging, double vote is still not possible.
+		if header_step <= self.step() + 1 {
+			let proposer_signature = try!(header_signature(header));
+			let ok_sig = try!(verify_address(self.step_proposer(header_step), &proposer_signature, &header.bare_hash()));
+			if ok_sig {
+				Ok(())
+			} else {
+				trace!(target: "poa", "verify_block_unordered: invalid seal signature");
+				try!(Err(BlockError::InvalidSeal))
+			}
+		} else {
+			trace!(target: "poa", "verify_block_unordered: block from the future");
+			try!(Err(BlockError::InvalidSeal))
+		}
+	}
+
+	fn verify_block_family(&self, header: &Header, parent: &Header, _block: Option<&[u8]>) -> Result<(), Error> {
+		// Don't calculate difficulty for genesis blocks.
+		if header.number() == 0 {
+			return Err(From::from(BlockError::RidiculousNumber(OutOfBounds { min: Some(1), max: None, found: header.number() })));
+		}
+
+		let step = try!(header_step(header));
+		// Check if parent is from a previous step.
+		if step == try!(header_step(parent)) { 
+			trace!(target: "poa", "Multiple blocks proposed for step {}.", step);
+			try!(Err(BlockError::DoubleVote(header.author().clone())));
+		}
+
+		// Check difficulty is correct given the two timestamps.
+		if header.difficulty() != parent.difficulty() {
+			return Err(From::from(BlockError::InvalidDifficulty(Mismatch { expected: *parent.difficulty(), found: *header.difficulty() })))
+		}
+		let gas_limit_divisor = self.our_params.gas_limit_bound_divisor;
+		let min_gas = parent.gas_limit().clone() - parent.gas_limit().clone() / gas_limit_divisor;
+		let max_gas = parent.gas_limit().clone() + parent.gas_limit().clone() / gas_limit_divisor;
+		if header.gas_limit() <= &min_gas || header.gas_limit() >= &max_gas {
+			return Err(From::from(BlockError::InvalidGasLimit(OutOfBounds { min: Some(min_gas), max: Some(max_gas), found: header.gas_limit().clone() })));
+		}
+		Ok(())
+	}
+
+	fn verify_transaction_basic(&self, t: &SignedTransaction, _header: &Header) -> Result<(), Error> {
+		try!(t.check_low_s());
+		Ok(())
+	}
+
+	fn verify_transaction(&self, t: &SignedTransaction, _header: &Header) -> Result<(), Error> {
+		t.sender().map(|_|()) // Perform EC recovery and cache sender
+	}
+
+	fn register_message_channel(&self, message_channel: IoChannel<ClientIoMessage>) {
+		let mut guard = self.message_channel.lock();
+		*guard = Some(message_channel);
+	}
+}
+
+#[cfg(test)]
+mod tests {
+	use util::*;
+	use env_info::EnvInfo;
+	use header::Header;
+	use error::{Error, BlockError};
+	use rlp::encode;
+	use block::*;
+	use tests::helpers::*;
+	use account_provider::AccountProvider;
+	use spec::Spec;
+	use std::time::UNIX_EPOCH;
+
+	#[test]
+	fn has_valid_metadata() {
+		let engine = Spec::new_test_round().engine;
+		assert!(!engine.name().is_empty());
+		assert!(engine.version().major >= 1);
+	}
+
+	#[test]
+	fn can_return_schedule() {
+		let engine = Spec::new_test_round().engine;
+		let schedule = engine.schedule(&EnvInfo {
+			number: 10000000,
+			author: 0.into(),
+			timestamp: 0,
+			difficulty: 0.into(),
+			last_hashes: Arc::new(vec![]),
+			gas_used: 0.into(),
+			gas_limit: 0.into(),
+		});
+
+		assert!(schedule.stack_limit > 0);
+	}
+
+	#[test]
+	fn verification_fails_on_short_seal() {
+		let engine = Spec::new_test_round().engine;
+		let header: Header = Header::default();
+
+		let verify_result = engine.verify_block_basic(&header, None);
+
+		match verify_result {
+			Err(Error::Block(BlockError::InvalidSealArity(_))) => {},
+			Err(_) => { panic!("should be block seal-arity mismatch error (got {:?})", verify_result); },
+			_ => { panic!("Should be error, got Ok"); },
+		}
+	}
+
+	#[test]
+	fn can_do_signature_verification_fail() {
+		let engine = Spec::new_test_round().engine;
+		let mut header: Header = Header::default();
+		header.set_seal(vec![encode(&H520::default()).to_vec()]);
+
+		let verify_result = engine.verify_block_unordered(&header, None);
+		assert!(verify_result.is_err());
+	}
+
+	#[test]
+	fn generates_seal_and_does_not_double_propose() {
+		let tap = AccountProvider::transient_provider();
+		let addr1 = tap.insert_account("1".sha3(), "1").unwrap();
+		tap.unlock_account_permanently(addr1, "1".into()).unwrap();
+		let addr2 = tap.insert_account("2".sha3(), "2").unwrap();
+		tap.unlock_account_permanently(addr2, "2".into()).unwrap();
+
+		let spec = Spec::new_test_round();
+		let engine = &*spec.engine;
+		let genesis_header = spec.genesis_header();
+		let mut db1 = get_temp_state_db().take();
+		spec.ensure_db_good(&mut db1).unwrap();
+		let mut db2 = get_temp_state_db().take();
+		spec.ensure_db_good(&mut db2).unwrap();
+		let last_hashes = Arc::new(vec![genesis_header.hash()]);
+		let b1 = OpenBlock::new(engine, Default::default(), false, db1, &genesis_header, last_hashes.clone(), addr1, (3141562.into(), 31415620.into()), vec![]).unwrap();
+		let b1 = b1.close_and_lock();
+		let b2 = OpenBlock::new(engine, Default::default(), false, db2, &genesis_header, last_hashes, addr2, (3141562.into(), 31415620.into()), vec![]).unwrap();
+		let b2 = b2.close_and_lock();
+
+		if let Some(seal) = engine.generate_seal(b1.block(), Some(&tap)) {
+			assert!(b1.clone().try_seal(engine, seal).is_ok());
+			// Second proposal is forbidden.
+			assert!(engine.generate_seal(b1.block(), Some(&tap)).is_none());
+		}
+
+		if let Some(seal) = engine.generate_seal(b2.block(), Some(&tap)) {
+			assert!(b2.clone().try_seal(engine, seal).is_ok());
+			// Second proposal is forbidden.
+			assert!(engine.generate_seal(b2.block(), Some(&tap)).is_none());
+		}
+	}
+
+	#[test]
+	fn proposer_switching() {
+		let mut header: Header = Header::default();
+		let tap = AccountProvider::transient_provider();
+		let addr = tap.insert_account("0".sha3(), "0").unwrap();
+
+		header.set_author(addr);
+
+		let engine = Spec::new_test_round().engine;
+
+		let signature = tap.sign(addr, Some("0".into()), header.bare_hash()).unwrap();
+		let mut step = UNIX_EPOCH.elapsed().unwrap().as_secs();
+		header.set_seal(vec![encode(&step).to_vec(), encode(&(&*signature as &[u8])).to_vec()]);
+		let first_ok = engine.verify_block_seal(&header).is_ok();
+		step = step + 1;
+		header.set_seal(vec![encode(&step).to_vec(), encode(&(&*signature as &[u8])).to_vec()]);
+		let second_ok = engine.verify_block_seal(&header).is_ok();
+
+		assert!(first_ok ^ second_ok);
+	}
+}
--- a/ethcore/src/engines/basic_authority.rs
+++ b/ethcore/src/engines/basic_authority.rs
@@ -181,13 +181,6 @@ impl Engine for BasicAuthority {
 	}
 }

-impl Header {
-	/// Get the none field of the header.
-	pub fn signature(&self) -> H520 {
-		::rlp::decode(&self.seal()[0])
-	}
-}
-
 #[cfg(test)]
 mod tests {
 	use util::*;
@@ -201,7 +194,7 @@ mod tests {

 	/// Create a new test chain spec with `BasicAuthority` consensus engine.
 	fn new_test_authority() -> Spec {
-		let bytes: &[u8] = include_bytes!("../../res/test_authority.json");
+		let bytes: &[u8] = include_bytes!("../../res/basic_authority.json");
 		Spec::load(bytes).expect("invalid chain spec")
 	}

--- a/ethcore/src/engines/instant_seal.rs
+++ b/ethcore/src/engines/instant_seal.rs
@@ -55,7 +55,7 @@ impl Engine for InstantSeal {
 	}

 	fn schedule(&self, _env_info: &EnvInfo) -> Schedule {
-		Schedule::new_homestead()
+		Schedule::new_post_eip150(usize::max_value(), false, false, false)
 	}

 	fn is_sealer(&self, _author: &Address) -> Option<bool> { Some(true) }
@@ -79,7 +79,7 @@ mod tests {
 		let tap = AccountProvider::transient_provider();
 		let addr = tap.insert_account("".sha3(), "").unwrap();

-		let spec = Spec::new_test_instant();
+		let spec = Spec::new_instant();
 		let engine = &*spec.engine;
 		let genesis_header = spec.genesis_header();
 		let mut db_result = get_temp_state_db();
@@ -95,7 +95,7 @@ mod tests {

 	#[test]
 	fn instant_cant_verify() {
-		let engine = Spec::new_test_instant().engine;
+		let engine = Spec::new_instant().engine;
 		let mut header: Header = Header::default();

 		assert!(engine.verify_block_basic(&header, None).is_ok());
--- a/ethcore/src/engines/mod.rs
+++ b/ethcore/src/engines/mod.rs
@@ -19,10 +19,12 @@
 mod null_engine;
 mod instant_seal;
 mod basic_authority;
+mod authority_round;

 pub use self::null_engine::NullEngine;
 pub use self::instant_seal::InstantSeal;
 pub use self::basic_authority::BasicAuthority;
+pub use self::authority_round::AuthorityRound;

 use util::*;
 use account_provider::AccountProvider;
@@ -32,6 +34,8 @@ use env_info::EnvInfo;
 use error::Error;
 use spec::CommonParams;
 use evm::Schedule;
+use io::IoChannel;
+use service::ClientIoMessage;
 use header::Header;
 use transaction::SignedTransaction;

@@ -140,5 +144,7 @@ pub trait Engine : Sync + Send {
 		self.builtins().get(a).expect("attempted to execute nonexistent builtin").execute(input, output);
 	}

+	/// Add a channel for communication with Client which can be used for sealing.
+	fn register_message_channel(&self, _message_channel: IoChannel<ClientIoMessage>) {}
 	// TODO: sealing stuff - though might want to leave this for later.
 }
--- a/ethcore/src/error.rs
+++ b/ethcore/src/error.rs
@@ -167,6 +167,8 @@ pub enum BlockError {
 	UnknownParent(H256),
 	/// Uncle parent given is unknown.
 	UnknownUncleParent(H256),
+	/// The same author issued different votes at the same step.
+	DoubleVote(H160),
 }

 impl fmt::Display for BlockError {
@@ -200,6 +202,7 @@ impl fmt::Display for BlockError {
 			RidiculousNumber(ref oob) => format!("Implausible block number. {}", oob),
 			UnknownParent(ref hash) => format!("Unknown parent: {}", hash),
 			UnknownUncleParent(ref hash) => format!("Unknown uncle parent: {}", hash),
+			DoubleVote(ref address) => format!("Author {} issued too many blocks.", address),
 		};

 		f.write_fmt(format_args!("Block error ({})", msg))
--- a/ethcore/src/ethereum/ethash.rs
+++ b/ethcore/src/ethereum/ethash.rs
@@ -73,7 +73,9 @@ pub struct EthashParams {
 	/// Number of first block where ECIP-1010 begins.
 	pub ecip1010_pause_transition: u64,
 	/// Number of first block where ECIP-1010 ends.
-	pub ecip1010_continue_transition: u64
+	pub ecip1010_continue_transition: u64,
+	/// Maximum amount of code that can be deploying into a contract.
+	pub max_code_size: u64,
 }

 impl From<ethjson::spec::EthashParams> for EthashParams {
@@ -87,19 +89,20 @@ impl From<ethjson::spec::EthashParams> for EthashParams {
 			block_reward: p.block_reward.into(),
 			registrar: p.registrar.map_or_else(Address::new, Into::into),
 			homestead_transition: p.homestead_transition.map_or(0, Into::into),
-			dao_hardfork_transition: p.dao_hardfork_transition.map_or(0x7fffffffffffffff, Into::into),
+			dao_hardfork_transition: p.dao_hardfork_transition.map_or(u64::max_value(), Into::into),
 			dao_hardfork_beneficiary: p.dao_hardfork_beneficiary.map_or_else(Address::new, Into::into),
 			dao_hardfork_accounts: p.dao_hardfork_accounts.unwrap_or_else(Vec::new).into_iter().map(Into::into).collect(),
-			difficulty_hardfork_transition: p.difficulty_hardfork_transition.map_or(0x7fffffffffffffff, Into::into),
+			difficulty_hardfork_transition: p.difficulty_hardfork_transition.map_or(u64::max_value(), Into::into),
 			difficulty_hardfork_bound_divisor: p.difficulty_hardfork_bound_divisor.map_or(p.difficulty_bound_divisor.into(), Into::into),
-			bomb_defuse_transition: p.bomb_defuse_transition.map_or(0x7fffffffffffffff, Into::into),
+			bomb_defuse_transition: p.bomb_defuse_transition.map_or(u64::max_value(), Into::into),
 			eip150_transition: p.eip150_transition.map_or(0, Into::into),
 			eip155_transition: p.eip155_transition.map_or(0, Into::into),
 			eip160_transition: p.eip160_transition.map_or(0, Into::into),
 			eip161abc_transition: p.eip161abc_transition.map_or(0, Into::into),
-			eip161d_transition: p.eip161d_transition.map_or(0x7fffffffffffffff, Into::into),
-			ecip1010_pause_transition: p.ecip1010_pause_transition.map_or(0x7fffffffffffffff, Into::into),
-			ecip1010_continue_transition: p.ecip1010_continue_transition.map_or(0x7fffffffffffffff, Into::into),
+			eip161d_transition: p.eip161d_transition.map_or(u64::max_value(), Into::into),
+			ecip1010_pause_transition: p.ecip1010_pause_transition.map_or(u64::max_value(), Into::into),
+			ecip1010_continue_transition: p.ecip1010_continue_transition.map_or(u64::max_value(), Into::into),
+			max_code_size: p.max_code_size.map_or(u64::max_value(), Into::into),
 		}
 	}
 }
@@ -152,6 +155,7 @@ impl Engine for Ethash {
 			Schedule::new_homestead()
 		} else {
 			Schedule::new_post_eip150(
+				self.ethash_params.max_code_size as usize,
 				env_info.number >= self.ethash_params.eip160_transition,
 				env_info.number >= self.ethash_params.eip161abc_transition,
 				env_info.number >= self.ethash_params.eip161d_transition
--- a/ethcore/src/evm/schedule.rs
+++ b/ethcore/src/evm/schedule.rs
@@ -70,6 +70,8 @@ pub struct Schedule {
 	pub quad_coeff_div: usize,
 	/// Cost for contract length when executing `CREATE`
 	pub create_data_gas: usize,
+	/// Maximum code size when creating a contract.
+	pub create_data_limit: usize,
 	/// Transaction cost
 	pub tx_gas: usize,
 	/// `CREATE` transaction cost
@@ -111,7 +113,7 @@ impl Schedule {
 	}

 	/// Schedule for the post-EIP-150-era of the Ethereum main net.
-	pub fn new_post_eip150(fix_exp: bool, no_empty: bool, kill_empty: bool) -> Schedule {
+	pub fn new_post_eip150(max_code_size: usize, fix_exp: bool, no_empty: bool, kill_empty: bool) -> Schedule {
 		Schedule {
 			exceptional_failed_code_deposit: true,
 			have_delegate_call: true,
@@ -139,6 +141,7 @@ impl Schedule {
 			memory_gas: 3,
 			quad_coeff_div: 512,
 			create_data_gas: 200,
+			create_data_limit: max_code_size,
 			tx_gas: 21000,
 			tx_create_gas: 53000,
 			tx_data_zero_gas: 4,
@@ -183,6 +186,7 @@ impl Schedule {
 			memory_gas: 3,
 			quad_coeff_div: 512,
 			create_data_gas: 200,
+			create_data_limit: usize::max_value(),
 			tx_gas: 21000,
 			tx_create_gas: tcg,
 			tx_data_zero_gas: 4,
--- a/ethcore/src/externalities.rs
+++ b/ethcore/src/externalities.rs
@@ -242,7 +242,7 @@ impl<'a, T, V> Ext for Externalities<'a, T, V> where T: 'a + Tracer, V: 'a + VMT
 			},
 			OutputPolicy::InitContract(ref mut copy) => {
 				let return_cost = U256::from(data.len()) * U256::from(self.schedule.create_data_gas);
-				if return_cost > *gas {
+				if return_cost > *gas || data.len() > self.schedule.create_data_limit {
 					return match self.schedule.exceptional_failed_code_deposit {
 						true => Err(evm::Error::OutOfGas),
 						false => Ok(*gas)
--- a/ethcore/src/miner/miner.rs
+++ b/ethcore/src/miner/miner.rs
@@ -212,7 +212,8 @@ pub struct Miner {
 	sealing_block_last_request: Mutex<u64>,
 	// for sealing...
 	options: MinerOptions,
-	seals_internally: bool,
+	/// Does the node perform internal (without work) sealing.
+	pub seals_internally: bool,

 	gas_range_target: RwLock<(U256, U256)>,
 	author: RwLock<Address>,
@@ -267,6 +268,11 @@ impl Miner {
 		}
 	}

+	/// Creates new instance of miner with accounts and with given spec.
+	pub fn with_spec_and_accounts(spec: &Spec, accounts: Option<Arc<AccountProvider>>) -> Miner {
+		Miner::new_raw(Default::default(), GasPricer::new_fixed(20_000_000_000u64.into()), spec, accounts)
+	}
+
 	/// Creates new instance of miner without accounts, but with given spec.
 	pub fn with_spec(spec: &Spec) -> Miner {
 		Miner::new_raw(Default::default(), GasPricer::new_fixed(20_000_000_000u64.into()), spec, None)
@@ -429,6 +435,7 @@ impl Miner {
 			let last_request = *self.sealing_block_last_request.lock();
 			let should_disable_sealing = !self.forced_sealing()
 				&& !has_local_transactions
+				&& !self.seals_internally
 				&& best_block > last_request
 				&& best_block - last_request > SEALING_TIMEOUT_IN_BLOCKS;

@@ -472,9 +479,10 @@ impl Miner {

 	/// Uses Engine to seal the block internally and then imports it to chain.
 	fn seal_and_import_block_internally(&self, chain: &MiningBlockChainClient, block: ClosedBlock) -> bool {
-		if !block.transactions().is_empty() {
+		if !block.transactions().is_empty() || self.forced_sealing() {
 			if let Ok(sealed) = self.seal_block_internally(block) {
 				if chain.import_block(sealed.rlp_bytes()).is_ok() {
+					trace!(target: "miner", "import_block_internally: imported internally sealed block");
 					return true
 				}
 			}
@@ -773,7 +781,7 @@ impl MinerService for Miner {
 		chain: &MiningBlockChainClient,
 		transactions: Vec<SignedTransaction>
 	) -> Vec<Result<TransactionImportResult, Error>> {
-
+		trace!(target: "external_tx", "Importing external transactions");
 		let results = {
 			let mut transaction_queue = self.transaction_queue.lock();
 			self.add_transactions_to_queue(
@@ -1251,7 +1259,7 @@ mod tests {

 	#[test]
 	fn internal_seals_without_work() {
-		let miner = Miner::with_spec(&Spec::new_test_instant());
+		let miner = Miner::with_spec(&Spec::new_instant());

 		let c = generate_dummy_client(2);
 		let client = c.reference().as_ref();
--- a/ethcore/src/service.rs
+++ b/ethcore/src/service.rs
@@ -48,6 +48,8 @@ pub enum ClientIoMessage {
 	FeedBlockChunk(H256, Bytes),
 	/// Take a snapshot for the block with given number.
 	TakeSnapshot(u64),
+	/// Trigger sealing update (useful for internal sealing).
+	UpdateSealing,
 }

 /// Client service setup. Creates and registers client and network services with the IO subsystem.
@@ -111,6 +113,8 @@ impl ClientService {
 		});
 		try!(io_service.register_handler(client_io));

+		spec.engine.register_message_channel(io_service.channel());
+
 		let stop_guard = ::devtools::StopGuard::new();
 		run_ipc(ipc_path, client.clone(), snapshot.clone(), stop_guard.share());

@@ -213,8 +217,11 @@ impl IoHandler<ClientIoMessage> for ClientIoHandler {
 				if let Err(e) = res {
 					debug!(target: "snapshot", "Failed to initialize periodic snapshot thread: {:?}", e);
 				}
-
-			}
+			},
+			ClientIoMessage::UpdateSealing => {
+				trace!(target: "authorityround", "message: UpdateSealing");
+				self.client.update_sealing()
+			},
 			_ => {} // ignore other messages
 		}
 	}
--- a/ethcore/src/snapshot/account.rs
+++ b/ethcore/src/snapshot/account.rs
@@ -19,11 +19,11 @@
 use account_db::{AccountDB, AccountDBMut};
 use snapshot::Error;

-use util::{U256, FixedHash, H256, Bytes, HashDB, DBValue, SHA3_EMPTY, SHA3_NULL_RLP};
+use util::{U256, FixedHash, H256, Bytes, HashDB, SHA3_EMPTY, SHA3_NULL_RLP};
 use util::trie::{TrieDB, Trie};
 use rlp::{Rlp, RlpStream, Stream, UntrustedRlp, View};

-use std::collections::{HashMap, HashSet};
+use std::collections::HashSet;

 // An empty account -- these are replaced with RLP null data for a space optimization.
 const ACC_EMPTY: Account = Account {
@@ -150,7 +150,6 @@ impl Account {
 	pub fn from_fat_rlp(
 		acct_db: &mut AccountDBMut,
 		rlp: UntrustedRlp,
-		code_map: &HashMap<H256, Bytes>,
 	) -> Result<(Self, Option<Bytes>), Error> {
 		use util::{TrieDBMut, TrieMut};

@@ -177,9 +176,6 @@ impl Account {
 			}
 			CodeState::Hash => {
 				let code_hash = try!(rlp.val_at(3));
-				if let Some(code) = code_map.get(&code_hash) {
-					acct_db.emplace(code_hash.clone(), DBValue::from_slice(code));
-				}

 				(code_hash, None)
 			}
@@ -229,7 +225,7 @@ mod tests {
 	use util::{Address, FixedHash, H256, HashDB, DBValue};
 	use rlp::{UntrustedRlp, View};

-	use std::collections::{HashSet, HashMap};
+	use std::collections::HashSet;

 	use super::{ACC_EMPTY, Account};

@@ -250,7 +246,7 @@ mod tests {

 		let fat_rlp = account.to_fat_rlp(&AccountDB::new(db.as_hashdb(), &addr), &mut Default::default()).unwrap();
 		let fat_rlp = UntrustedRlp::new(&fat_rlp);
-		assert_eq!(Account::from_fat_rlp(&mut AccountDBMut::new(db.as_hashdb_mut(), &addr), fat_rlp, &Default::default()).unwrap().0, account);
+		assert_eq!(Account::from_fat_rlp(&mut AccountDBMut::new(db.as_hashdb_mut(), &addr), fat_rlp).unwrap().0, account);
 	}

 	#[test]
@@ -275,7 +271,7 @@ mod tests {

 		let fat_rlp = account.to_fat_rlp(&AccountDB::new(db.as_hashdb(), &addr), &mut Default::default()).unwrap();
 		let fat_rlp = UntrustedRlp::new(&fat_rlp);
-		assert_eq!(Account::from_fat_rlp(&mut AccountDBMut::new(db.as_hashdb_mut(), &addr), fat_rlp, &Default::default()).unwrap().0, account);
+		assert_eq!(Account::from_fat_rlp(&mut AccountDBMut::new(db.as_hashdb_mut(), &addr), fat_rlp).unwrap().0, account);
 	}

 	#[test]
@@ -318,12 +314,11 @@ mod tests {
 		let fat_rlp1 = UntrustedRlp::new(&fat_rlp1);
 		let fat_rlp2 = UntrustedRlp::new(&fat_rlp2);

-		let code_map = HashMap::new();
-		let (acc, maybe_code) = Account::from_fat_rlp(&mut AccountDBMut::new(db.as_hashdb_mut(), &addr2), fat_rlp2, &code_map).unwrap();
+		let (acc, maybe_code) = Account::from_fat_rlp(&mut AccountDBMut::new(db.as_hashdb_mut(), &addr2), fat_rlp2).unwrap();
 		assert!(maybe_code.is_none());
 		assert_eq!(acc, account2);

-		let (acc, maybe_code) = Account::from_fat_rlp(&mut AccountDBMut::new(db.as_hashdb_mut(), &addr1), fat_rlp1, &code_map).unwrap();
+		let (acc, maybe_code) = Account::from_fat_rlp(&mut AccountDBMut::new(db.as_hashdb_mut(), &addr1), fat_rlp1).unwrap();
 		assert_eq!(maybe_code, Some(b"this is definitely code".to_vec()));
 		assert_eq!(acc, account1);
 	}
@@ -332,9 +327,8 @@ mod tests {
 	fn encoding_empty_acc() {
 		let mut db = get_temp_state_db();
 		let mut used_code = HashSet::new();
-		let code_map = HashMap::new();

 		assert_eq!(ACC_EMPTY.to_fat_rlp(&AccountDB::new(db.as_hashdb(), &Address::default()), &mut used_code).unwrap(), ::rlp::NULL_RLP.to_vec());
-		assert_eq!(Account::from_fat_rlp(&mut AccountDBMut::new(db.as_hashdb_mut(), &Address::default()), UntrustedRlp::new(&::rlp::NULL_RLP), &code_map).unwrap(), (ACC_EMPTY, None));
+		assert_eq!(Account::from_fat_rlp(&mut AccountDBMut::new(db.as_hashdb_mut(), &Address::default()), UntrustedRlp::new(&::rlp::NULL_RLP)).unwrap(), (ACC_EMPTY, None));
 	}
 }
--- a/ethcore/src/snapshot/mod.rs
+++ b/ethcore/src/snapshot/mod.rs
@@ -389,7 +389,7 @@ pub fn chunk_state<'a>(db: &HashDB, root: &H256, writer: &Mutex<SnapshotWriter +
 pub struct StateRebuilder {
 	db: Box<JournalDB>,
 	state_root: H256,
-	code_map: HashMap<H256, Bytes>, // maps code hashes to code itself.
+	known_code: HashMap<H256, H256>, // code hashes mapped to first account with this code.
 	missing_code: HashMap<H256, Vec<H256>>, // maps code hashes to lists of accounts missing that code.
 	bloom: Bloom,
 }
@@ -400,7 +400,7 @@ impl StateRebuilder {
 		StateRebuilder {
 			db: journaldb::new(db.clone(), pruning, ::db::COL_STATE),
 			state_root: SHA3_NULL_RLP,
-			code_map: HashMap::new(),
+			known_code: HashMap::new(),
 			missing_code: HashMap::new(),
 			bloom: StateDB::load_bloom(&*db),
 		}
@@ -419,7 +419,7 @@ impl StateRebuilder {
 			self.db.as_hashdb_mut(),
 			rlp,
 			&mut pairs,
-			&self.code_map,
+			&self.known_code,
 			flag
 		));

@@ -428,13 +428,13 @@ impl StateRebuilder {
 		}

 		// patch up all missing code. must be done after collecting all new missing code entries.
-		for (code_hash, code) in status.new_code {
+		for (code_hash, code, first_with) in status.new_code {
 			for addr_hash in self.missing_code.remove(&code_hash).unwrap_or_else(Vec::new) {
 				let mut db = AccountDBMut::from_hash(self.db.as_hashdb_mut(), addr_hash);
 				db.emplace(code_hash, DBValue::from_slice(&code));
 			}

-			self.code_map.insert(code_hash, code);
+			self.known_code.insert(code_hash, first_with);
 		}

 		let backing = self.db.backing().clone();
@@ -482,7 +482,8 @@ impl StateRebuilder {

 #[derive(Default)]
 struct RebuiltStatus {
-	new_code: Vec<(H256, Bytes)>, // new code that's become available.
+	// new code that's become available. (code_hash, code, addr_hash)
+	new_code: Vec<(H256, Bytes, H256)>,
 	missing_code: Vec<(H256, H256)>, // accounts that are missing code.
 }

@@ -492,10 +493,9 @@ fn rebuild_accounts(
 	db: &mut HashDB,
 	account_fat_rlps: UntrustedRlp,
 	out_chunk: &mut [(H256, Bytes)],
-	code_map: &HashMap<H256, Bytes>,
-	abort_flag: &AtomicBool
-) -> Result<RebuiltStatus, ::error::Error>
-{
+	known_code: &HashMap<H256, H256>,
+	abort_flag: &AtomicBool,
+) -> Result<RebuiltStatus, ::error::Error> {
 	let mut status = RebuiltStatus::default();
 	for (account_rlp, out) in account_fat_rlps.into_iter().zip(out_chunk) {
 		if !abort_flag.load(Ordering::SeqCst) { return Err(Error::RestorationAborted.into()) }
@@ -504,17 +504,33 @@ fn rebuild_accounts(
 		let fat_rlp = try!(account_rlp.at(1));

 		let thin_rlp = {
-			let mut acct_db = AccountDBMut::from_hash(db, hash);

 			// fill out the storage trie and code while decoding.
-			let (acc, maybe_code) = try!(Account::from_fat_rlp(&mut acct_db, fat_rlp, code_map));
+			let (acc, maybe_code) = {
+				let mut acct_db = AccountDBMut::from_hash(db, hash);
+				try!(Account::from_fat_rlp(&mut acct_db, fat_rlp))
+			};

 			let code_hash = acc.code_hash().clone();
 			match maybe_code {
-				Some(code) => status.new_code.push((code_hash, code)),
+				// new inline code
+				Some(code) => status.new_code.push((code_hash, code, hash)),
 				None => {
-					if code_hash != ::util::SHA3_EMPTY && !code_map.contains_key(&code_hash) {
-						status.missing_code.push((hash, code_hash));
+					if code_hash != ::util::SHA3_EMPTY {
+						// see if this code has already been included inline
+						match known_code.get(&code_hash) {
+							Some(&first_with) => {
+								// if so, load it from the database.
+								let code = try!(AccountDB::from_hash(db, first_with)
+									.get(&code_hash)
+									.ok_or_else(|| Error::MissingCode(vec![first_with])));
+
+								// and write it again under a different mangled key
+								AccountDBMut::from_hash(db, hash).emplace(code_hash, code);
+							}
+							// if not, queue it up to be filled later
+							None => status.missing_code.push((hash, code_hash)),
+						}
 					}
 				}
 			}
--- a/ethcore/src/snapshot/tests/state.rs
+++ b/ethcore/src/snapshot/tests/state.rs
@@ -17,6 +17,7 @@
 //! State snapshotting tests.

 use snapshot::{chunk_state, Error as SnapshotError, Progress, StateRebuilder};
+use snapshot::account::Account;
 use snapshot::io::{PackedReader, PackedWriter, SnapshotReader, SnapshotWriter};
 use super::helpers::{compare_dbs, StateProducer};

@@ -30,6 +31,8 @@ use util::memorydb::MemoryDB;
 use util::Mutex;
 use devtools::RandomTempPath;

+use util::sha3::SHA3_NULL_RLP;
+
 use std::sync::Arc;
 use std::sync::atomic::AtomicBool;

@@ -88,6 +91,58 @@ fn snap_and_restore() {
 	compare_dbs(&old_db, new_db.as_hashdb());
 }

+#[test]
+fn get_code_from_prev_chunk() {
+	use std::collections::HashSet;
+	use rlp::{RlpStream, Stream};
+	use util::{HashDB, H256, FixedHash, U256, Hashable};
+
+	use account_db::{AccountDBMut, AccountDB};
+
+	let code = b"this is definitely code";
+	let mut used_code = HashSet::new();
+	let mut acc_stream = RlpStream::new_list(4);
+	acc_stream.append(&U256::default())
+		.append(&U256::default())
+		.append(&SHA3_NULL_RLP)
+		.append(&code.sha3());
+
+	let (h1, h2) = (H256::random(), H256::random());
+
+	// two accounts with the same code, one per chunk.
+	// first one will have code inlined,
+	// second will just have its hash.
+	let thin_rlp = acc_stream.out();
+	let acc1 = Account::from_thin_rlp(&thin_rlp);
+	let acc2 = Account::from_thin_rlp(&thin_rlp);
+
+	let mut make_chunk = |acc: Account, hash| {
+		let mut db = MemoryDB::new();
+		AccountDBMut::from_hash(&mut db, hash).insert(&code[..]);
+
+		let fat_rlp = acc.to_fat_rlp(&AccountDB::from_hash(&db, hash), &mut used_code).unwrap();
+
+		let mut stream = RlpStream::new_list(1);
+		stream.begin_list(2).append(&hash).append_raw(&fat_rlp, 1);
+		stream.out()
+	};
+
+	let chunk1 = make_chunk(acc1, h1);
+	let chunk2 = make_chunk(acc2, h2);
+
+	let db_path = RandomTempPath::create_dir();
+	let db_cfg = DatabaseConfig::with_columns(::db::NUM_COLUMNS);
+	let new_db = Arc::new(Database::open(&db_cfg, &db_path.to_string_lossy()).unwrap());
+
+	let mut rebuilder = StateRebuilder::new(new_db, Algorithm::Archive);
+	let flag = AtomicBool::new(true);
+
+	rebuilder.feed(&chunk1, &flag).unwrap();
+	rebuilder.feed(&chunk2, &flag).unwrap();
+
+	rebuilder.check_missing().unwrap();
+}
+
 #[test]
 fn checks_flag() {
 	let mut producer = StateProducer::new();
--- a/ethcore/src/spec/spec.rs
+++ b/ethcore/src/spec/spec.rs
@@ -18,7 +18,7 @@

 use util::*;
 use builtin::Builtin;
-use engines::{Engine, NullEngine, InstantSeal, BasicAuthority};
+use engines::{Engine, NullEngine, InstantSeal, BasicAuthority, AuthorityRound};
 use pod_state::*;
 use account_db::*;
 use header::{BlockNumber, Header};
@@ -135,6 +135,12 @@ impl From<ethjson::spec::Spec> for Spec {
 	}
 }

+macro_rules! load_bundled {
+	($e:expr) => {
+		Spec::load(include_bytes!(concat!("../../res/", $e, ".json")) as &[u8]).expect(concat!("Chain spec ", $e, " is invalid."))
+	};
+}
+
 impl Spec {
 	/// Convert engine spec into a arc'd Engine of the right underlying type.
 	/// TODO avoid this hard-coded nastiness - use dynamic-linked plugin framework instead.
@@ -144,6 +150,7 @@ impl Spec {
 			ethjson::spec::Engine::InstantSeal => Arc::new(InstantSeal::new(params, builtins)),
 			ethjson::spec::Engine::Ethash(ethash) => Arc::new(ethereum::Ethash::new(params, From::from(ethash.params), builtins)),
 			ethjson::spec::Engine::BasicAuthority(basic_authority) => Arc::new(BasicAuthority::new(params, From::from(basic_authority.params), builtins)),
+			ethjson::spec::Engine::AuthorityRound(authority_round) => AuthorityRound::new(params, From::from(authority_round.params), builtins).expect("Consensus engine could not be started."),
 		}
 	}

@@ -267,19 +274,17 @@ impl Spec {
 	}

 	/// Create a new Spec which conforms to the Frontier-era Morden chain except that it's a NullEngine consensus.
-	pub fn new_test() -> Self {
-		Spec::load(include_bytes!("../../res/null_morden.json") as &[u8]).expect("null_morden.json is invalid")
-	}
+	pub fn new_test() -> Spec { load_bundled!("null_morden") }

 	/// Create a new Spec which is a NullEngine consensus with a premine of address whose secret is sha3('').
-	pub fn new_null() -> Self {
-		Spec::load(include_bytes!("../../res/null.json") as &[u8]).expect("null.json is invalid")
-	}
+	pub fn new_null() -> Spec { load_bundled!("null") }

 	/// Create a new Spec with InstantSeal consensus which does internal sealing (not requiring work).
-	pub fn new_test_instant() -> Self {
-		Spec::load(include_bytes!("../../res/instant_seal.json") as &[u8]).expect("instant_seal.json is invalid")
-	}
+	pub fn new_instant() -> Spec { load_bundled!("instant_seal") }
+
+	/// Create a new Spec with AuthorityRound consensus which does internal sealing (not requiring work).
+	/// Accounts with secrets "1".sha3() and "2".sha3() are the authorities.
+	pub fn new_test_round() -> Self { load_bundled!("authority_round") }
 }

 #[cfg(test)]
--- a/ethcore/src/tests/helpers.rs
+++ b/ethcore/src/tests/helpers.rs
@@ -433,18 +433,19 @@ pub fn get_default_ethash_params() -> EthashParams{
 		block_reward: U256::from(0),
 		registrar: "0000000000000000000000000000000000000001".into(),
 		homestead_transition: 1150000,
-		dao_hardfork_transition: 0x7fffffffffffffff,
+		dao_hardfork_transition: u64::max_value(),
 		dao_hardfork_beneficiary: "0000000000000000000000000000000000000001".into(),
 		dao_hardfork_accounts: vec![],
-		difficulty_hardfork_transition: 0x7fffffffffffffff,
+		difficulty_hardfork_transition: u64::max_value(),
 		difficulty_hardfork_bound_divisor: U256::from(0),
-		bomb_defuse_transition: 0x7fffffffffffffff,
-		eip150_transition: 0x7fffffffffffffff,
-		eip155_transition: 0x7fffffffffffffff,
-		eip160_transition: 0x7fffffffffffffff,
-		eip161abc_transition: 0x7fffffffffffffff,
-		eip161d_transition: 0x7fffffffffffffff,
-		ecip1010_pause_transition: 0x7fffffffffffffff,
-		ecip1010_continue_transition: 0x7fffffffffffffff
+		bomb_defuse_transition: u64::max_value(),
+		eip150_transition: u64::max_value(),
+		eip155_transition: u64::max_value(),
+		eip160_transition: u64::max_value(),
+		eip161abc_transition: u64::max_value(),
+		eip161d_transition: u64::max_value(),
+		ecip1010_pause_transition: u64::max_value(),
+		ecip1010_continue_transition: u64::max_value(),
+		max_code_size: u64::max_value(),
 	}
 }