Merge branch 'master' of github.com:gavofyork/ethcore into network

2016-01-09 10:26:31 +01:00 · 2016-01-09 10:26:31 +01:00 · 86dfa1b425
commit 86dfa1b425
parent f1cdc0a17d ca6a20922f
14 changed files with 27436 additions and 86 deletions
--- a/Cargo.toml
+++ b/Cargo.toml
@ -14,6 +14,7 @@ rustc-serialize = "0.3"
 flate2 = "0.2"
 rocksdb = "0.2.1"
 heapsize = "0.2.0"
+rust-crypto = "0.2.34"

 evmjit = { path = "rust-evmjit", optional = true }

--- a/res/frontier.json
+++ b/res/frontier.json
--- a/res/morden.json
+++ b/res/morden.json
@ -0,0 +1,34 @@
+{
+	"engineName": "Ethash",
+	"params": {
+		"accountStartNonce": "0x0100000",
+		"frontierCompatibilityModeLimit": "0xfffa2990",
+		"maximumExtraDataSize": "0x20",
+		"tieBreakingGas": false,
+		"minGasLimit": "0x1388",
+		"gasLimitBoundDivisor": "0x0400",
+		"minimumDifficulty": "0x020000",
+		"difficultyBoundDivisor": "0x0800",
+		"durationLimit": "0x0d",
+		"blockReward": "0x4563918244F40000",
+		"registrar": "",
+		"networkID" : "0x2"
+	},
+	"genesis": {
+		"nonce": "0x00006d6f7264656e",
+		"difficulty": "0x20000",
+		"mixHash": "0x00000000000000000000000000000000000000647572616c65787365646c6578",
+		"author": "0x0000000000000000000000000000000000000000",
+		"timestamp": "0x00",
+		"parentHash": "0x0000000000000000000000000000000000000000000000000000000000000000",
+		"extraData": "0x",
+		"gasLimit": "0x2fefd8"
+	},
+	"accounts": {
+		"0000000000000000000000000000000000000001": { "balance": "1", "nonce": "1048576", "builtin": { "name": "ecrecover", "linear": { "base": 3000, "word": 0 } } },
+		"0000000000000000000000000000000000000002": { "balance": "1", "nonce": "1048576", "builtin": { "name": "sha256", "linear": { "base": 60, "word": 12 } } },
+		"0000000000000000000000000000000000000003": { "balance": "1", "nonce": "1048576", "builtin": { "name": "ripemd160", "linear": { "base": 600, "word": 120 } } },
+		"0000000000000000000000000000000000000004": { "balance": "1", "nonce": "1048576", "builtin": { "name": "identity", "linear": { "base": 15, "word": 3 } } },
+		"102e61f5d8f9bc71d0ad4a084df4e65e05ce0e1c": { "balance": "1606938044258990275541962092341162602522202993782792835301376", "nonce": "1048576" }
+	}
+}
--- a/src/block.rs
+++ b/src/block.rs
@ -0,0 +1,160 @@
+use std::collections::hash_set::*;
+use util::hash::*;
+use util::bytes::*;
+use util::uint::*;
+use util::error::*;
+use util::overlaydb::*;
+use transaction::*;
+use receipt::*;
+use blockchain::*;
+use engine::*;
+use header::*;
+use env_info::*;
+use state::*;
+
+/// A transaction/receipt execution entry.
+pub struct Entry {
+	transaction: Transaction,
+	receipt: Receipt,
+}
+
+/// Internal type for a block's common elements.
+pub struct Block {
+	header: Header,
+
+	/// State is the most final state in the block.
+	state: State,
+
+	archive: Vec<Entry>,
+	archive_set: HashSet<H256>,
+}
+
+impl Block {
+	fn new(state: State) -> Block {
+		Block {
+			header: Header::new(),
+			state: state,
+			archive: Vec::new(),
+			archive_set: HashSet::new(),
+		}
+	}
+
+	pub fn state_mut(&mut self) -> &mut State { &mut self.state }
+}
+
+/// Trait for a object that is_a `Block`.
+pub trait IsBlock {
+	/// Get the block associated with this object.
+	fn block(&self) -> &Block;
+
+	/// Get the header associated with this object's block.
+	fn header(&self) -> &Header { &self.block().header }
+
+	/// Get the final state associated with this object's block.
+	fn state(&self) -> &State { &self.block().state }
+
+	/// Get all information on transactions in this block.
+	fn archive(&self) -> &Vec<Entry> { &self.block().archive }
+}
+
+impl IsBlock for Block {
+	fn block(&self) -> &Block { self }
+}
+
+/// Block that is ready for transactions to be added.
+///
+/// It's a bit like a Vec<Transaction>, eccept that whenever a transaction is pushed, we execute it and
+/// maintain the system `state()`. We also archive execution receipts in preparation for later block creation.
+pub struct OpenBlock<'engine> {
+	block: Block,
+	engine: &'engine Engine,
+	last_hashes: LastHashes,
+}
+
+/// Just like OpenBlock, except that we've applied `Engine::on_close_block`, finished up the non-seal header fields,
+/// and collected the uncles.
+///
+/// There is no function available to push a transaction. If you want that you'll need to `reopen()` it.
+pub struct ClosedBlock<'engine> {
+	open_block: OpenBlock<'engine>,
+	_uncles: Vec<Header>,
+}
+
+/// A block that has a valid seal.
+///
+/// The block's header has valid seal arguments. The block cannot be reversed into a ClosedBlock or OpenBlock.
+pub struct SealedBlock {
+	block: Block,
+	_bytes: Bytes,
+}
+
+impl<'engine> OpenBlock<'engine> {
+	/// Create a new OpenBlock ready for transaction pushing.
+	pub fn new<'a>(engine: &'a Engine, db: OverlayDB, parent: &Header, last_hashes: LastHashes) -> OpenBlock<'a> {
+		let mut r = OpenBlock {
+			block: Block::new(State::from_existing(db, parent.state_root.clone(), engine.account_start_nonce())),
+			engine: engine,
+			last_hashes: last_hashes,
+		};
+
+		engine.populate_from_parent(&mut r.block.header, parent);
+		engine.on_new_block(&mut r.block);
+		r
+	}
+
+	/// Get the environment info concerning this block.
+	pub fn env_info(&self) -> EnvInfo {
+		// TODO: memoise.
+		EnvInfo {
+			number: self.block.header.number.clone(),
+			author: self.block.header.author.clone(),
+			timestamp: self.block.header.timestamp.clone(),
+			difficulty: self.block.header.difficulty.clone(),
+			last_hashes: self.last_hashes.clone(),
+			gas_used: if let Some(ref t) = self.block.archive.last() {t.receipt.gas_used} else {U256::from(0)},
+			gas_limit: self.block.header.gas_limit.clone(),
+		}
+	}
+
+	/// Push a transaction into the block. It will be executed, and archived together with the receipt.
+	pub fn push_transaction(&mut self, t: Transaction, h: Option<H256>) -> Result<&Receipt, EthcoreError> {
+		let env_info = self.env_info();
+		match self.block.state.apply(&env_info, self.engine, &t, true) {
+			Ok(x) => {
+				self.block.archive_set.insert(h.unwrap_or_else(||t.sha3()));
+				self.block.archive.push(Entry { transaction: t, receipt: x.receipt });
+				Ok(&self.block.archive.last().unwrap().receipt)
+			}
+			Err(x) => Err(x)
+		}
+	}
+
+	/// Turn this into a `ClosedBlock`. A BlockChain must be provided in order to figure ou the uncles.
+	pub fn close(self, _bc: &BlockChain) -> ClosedBlock { unimplemented!(); }
+}
+
+impl<'engine> IsBlock for OpenBlock<'engine> {
+	fn block(&self) -> &Block { &self.block }
+}
+
+impl<'engine> ClosedBlock<'engine> {
+	/// Get the hash of the header without seal arguments.
+	pub fn preseal_hash(&self) -> H256 { unimplemented!(); }
+
+	/// Turn this into a `ClosedBlock`. A BlockChain must be provided in order to figure ou the uncles.
+	pub fn seal(self, _seal_fields: Vec<Bytes>) -> SealedBlock { unimplemented!(); }
+
+	/// Turn this back into an `OpenBlock`.
+	pub fn reopen(self) -> OpenBlock<'engine> { unimplemented!(); }
+}
+
+impl<'engine> IsBlock for ClosedBlock<'engine> {
+	fn block(&self) -> &Block { &self.open_block.block }
+}
+
+impl SealedBlock {
+}
+
+impl IsBlock for SealedBlock {
+	fn block(&self) -> &Block { &self.block }
+}
--- a/src/builtin.rs
+++ b/src/builtin.rs
@ -1,4 +1,16 @@
+use std::cmp::min;
+use std::fmt;
 use util::uint::*;
+use util::hash::*;
+use util::sha3::*;
+use util::bytes::*;
+use rustc_serialize::json::Json;
+use std::io::Write;
+use util::crypto::*;
+use util::crypto::ec::*;
+use crypto::sha2::Sha256;
+use crypto::ripemd160::Ripemd160;
+use crypto::digest::Digest;

 /// Definition of a contract whose implementation is built-in. 
 pub struct Builtin {
@ -8,3 +20,259 @@ pub struct Builtin {
 	/// being placed into the second.
 	pub execute: Box<Fn(&[u8], &mut [u8])>,
 }
+
+impl fmt::Debug for Builtin {
+	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+		write!(f, "<Builtin>")
+	}
+}
+
+impl Builtin {
+	/// Create a new object from components.
+	pub fn new(cost: Box<Fn(usize) -> U256>, execute: Box<Fn(&[u8], &mut [u8])>) -> Builtin {
+		Builtin {cost: cost, execute: execute}
+	}
+
+	/// Create a new object from a builtin-function name with a linear cost associated with input size.
+	pub fn from_named_linear(name: &str, base_cost: usize, word_cost: usize) -> Option<Builtin> {
+		new_builtin_exec(name).map(|b| {
+			let cost = Box::new(move|s: usize| -> U256 {
+				U256::from(base_cost) + U256::from(word_cost) * U256::from((s + 31) / 32)
+			});
+			Self::new(cost, b)
+		})
+	}
+
+	/// Create a builtin from JSON.
+	///
+	/// JSON must be of the form `{ "name": "identity", "linear": {"base": 10, "word": 20} }`.
+	pub fn from_json(json: &Json) -> Option<Builtin> {
+		// NICE: figure out a more convenient means of handing errors here.
+		if let Json::String(ref name) = json["name"] {
+			if let Json::Object(ref o) = json["linear"] {
+				if let Json::U64(ref word) = o["word"] {
+					if let Json::U64(ref base) = o["base"] {
+						return Self::from_named_linear(&name[..], *base as usize, *word as usize);
+					}
+				}
+			}
+		}
+		None
+	}
+
+	/// Simple forwarder for cost.
+	pub fn cost(&self, s: usize) -> U256 { (*self.cost)(s) }
+
+	/// Simple forwarder for execute.
+	pub fn execute(&self, input: &[u8], output: &mut[u8]) { (*self.execute)(input, output); }
+}
+
+pub fn copy_to(src: &[u8], dest: &mut[u8]) {
+	// NICE: optimise
+	for i in 0..min(src.len(), dest.len()) {
+		dest[i] = src[i];
+	}
+}
+
+/// Create a new builtin executor according to `name`.
+/// TODO: turn in to a factory with dynamic registration.
+pub fn new_builtin_exec(name: &str) -> Option<Box<Fn(&[u8], &mut [u8])>> {
+	match name {
+		"identity" => Some(Box::new(move|input: &[u8], output: &mut[u8]| {
+			for i in 0..min(input.len(), output.len()) {
+				output[i] = input[i];
+			}
+		})),
+		"ecrecover" => Some(Box::new(move|input: &[u8], output: &mut[u8]| {
+			#[repr(packed)]
+			#[derive(Debug)]
+			struct InType {
+				hash: H256,
+				v: H256,
+				r: H256,
+				s: H256,
+			}
+			let mut it: InType = InType { hash: H256::new(), v: H256::new(), r: H256::new(), s: H256::new() };
+			it.copy_raw(input);
+			if it.v == H256::from(&U256::from(27)) || it.v == H256::from(&U256::from(28)) {
+				let s = Signature::from_rsv(&it.r, &it.s, it.v[31] - 27);
+				if is_valid(&s) {
+					match recover(&s, &it.hash) {
+						Ok(p) => {
+							let r = p.as_slice().sha3();
+							// NICE: optimise and separate out into populate-like function
+							for i in 0..min(32, output.len()) {
+								output[i] = if i < 12 {0} else {r[i]};
+							}
+						}
+						_ => {}
+					};
+				}
+			}
+		})),
+		"sha256" => Some(Box::new(move|input: &[u8], output: &mut[u8]| {
+			let mut sha = Sha256::new();
+			sha.input(input);
+			if output.len() >= 32 {
+				sha.result(output);
+			} else {
+				let mut ret = H256::new();
+				sha.result(ret.as_slice_mut());
+				copy_to(&ret, output);
+			}
+		})),
+		"ripemd160" => Some(Box::new(move|input: &[u8], output: &mut[u8]| {
+			let mut sha = Ripemd160::new();
+			sha.input(input);
+			let mut ret = H256::new();
+			sha.result(&mut ret.as_slice_mut()[12..32]);
+			copy_to(&ret, output);
+		})),
+		_ => None
+	}
+}
+
+#[test]
+fn identity() {
+	let f = new_builtin_exec("identity").unwrap();
+	let i = [0u8, 1, 2, 3];
+
+	let mut o2 = [255u8; 2];
+	f(&i[..], &mut o2[..]);
+	assert_eq!(i[0..2], o2);
+
+	let mut o4 = [255u8; 4];
+	f(&i[..], &mut o4[..]);
+	assert_eq!(i, o4);
+
+	let mut o8 = [255u8; 8];
+	f(&i[..], &mut o8[..]);
+	assert_eq!(i, o8[..4]);
+	assert_eq!([255u8; 4], o8[4..]);
+}
+
+#[test]
+fn sha256() {
+	use rustc_serialize::hex::FromHex;
+	let f = new_builtin_exec("sha256").unwrap();
+	let i = [0u8; 0];
+
+	let mut o = [255u8; 32];
+	f(&i[..], &mut o[..]);
+	assert_eq!(&o[..], &(FromHex::from_hex("e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855").unwrap())[..]);
+
+	let mut o8 = [255u8; 8];
+	f(&i[..], &mut o8[..]);
+	assert_eq!(&o8[..], &(FromHex::from_hex("e3b0c44298fc1c14").unwrap())[..]);
+
+	let mut o34 = [255u8; 34];
+	f(&i[..], &mut o34[..]);
+	assert_eq!(&o34[..], &(FromHex::from_hex("e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855ffff").unwrap())[..]);
+}
+
+#[test]
+fn ripemd160() {
+	use rustc_serialize::hex::FromHex;
+	let f = new_builtin_exec("ripemd160").unwrap();
+	let i = [0u8; 0];
+
+	let mut o = [255u8; 32];
+	f(&i[..], &mut o[..]);
+	assert_eq!(&o[..], &(FromHex::from_hex("0000000000000000000000009c1185a5c5e9fc54612808977ee8f548b2258d31").unwrap())[..]);
+
+	let mut o8 = [255u8; 8];
+	f(&i[..], &mut o8[..]);
+	assert_eq!(&o8[..], &(FromHex::from_hex("0000000000000000").unwrap())[..]);
+
+	let mut o34 = [255u8; 34];
+	f(&i[..], &mut o34[..]);
+	assert_eq!(&o34[..], &(FromHex::from_hex("0000000000000000000000009c1185a5c5e9fc54612808977ee8f548b2258d31ffff").unwrap())[..]);
+}
+
+#[test]
+fn ecrecover() {
+	use rustc_serialize::hex::FromHex;
+	/*let k = KeyPair::from_secret(b"test".sha3()).unwrap();
+	let a: Address = From::from(k.public().sha3());
+	println!("Address: {}", a);
+	let m = b"hello world".sha3();
+	println!("Message: {}", m);
+	let s = k.sign(&m).unwrap();
+	println!("Signed: {}", s);*/
+
+	let f = new_builtin_exec("ecrecover").unwrap();
+	let i = FromHex::from_hex("47173285a8d7341e5e972fc677286384f802f8ef42a5ec5f03bbfa254cb01fad000000000000000000000000000000000000000000000000000000000000001b650acf9d3f5f0a2c799776a1254355d5f4061762a237396a99a0e0e3fc2bcd6729514a0dacb2e623ac4abd157cb18163ff942280db4d5caad66ddf941ba12e03").unwrap();
+
+	let mut o = [255u8; 32];
+	f(&i[..], &mut o[..]);
+	assert_eq!(&o[..], &(FromHex::from_hex("000000000000000000000000c08b5542d177ac6686946920409741463a15dddb").unwrap())[..]);
+
+	let mut o8 = [255u8; 8];
+	f(&i[..], &mut o8[..]);
+	assert_eq!(&o8[..], &(FromHex::from_hex("0000000000000000").unwrap())[..]);
+
+	let mut o34 = [255u8; 34];
+	f(&i[..], &mut o34[..]);
+	assert_eq!(&o34[..], &(FromHex::from_hex("000000000000000000000000c08b5542d177ac6686946920409741463a15dddbffff").unwrap())[..]);
+
+	let i_bad = FromHex::from_hex("47173285a8d7341e5e972fc677286384f802f8ef42a5ec5f03bbfa254cb01fad000000000000000000000000000000000000000000000000000000000000001a650acf9d3f5f0a2c799776a1254355d5f4061762a237396a99a0e0e3fc2bcd6729514a0dacb2e623ac4abd157cb18163ff942280db4d5caad66ddf941ba12e03").unwrap();
+	let mut o = [255u8; 32];
+	f(&i_bad[..], &mut o[..]);
+	assert_eq!(&o[..], &(FromHex::from_hex("ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff").unwrap())[..]);
+
+	let i_bad = FromHex::from_hex("47173285a8d7341e5e972fc677286384f802f8ef42a5ec5f03bbfa254cb01fad000000000000000000000000000000000000000000000000000000000000001b000000000000000000000000000000000000000000000000000000000000001b0000000000000000000000000000000000000000000000000000000000000000").unwrap();
+	let mut o = [255u8; 32];
+	f(&i_bad[..], &mut o[..]);
+	assert_eq!(&o[..], &(FromHex::from_hex("ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff").unwrap())[..]);
+
+	let i_bad = FromHex::from_hex("47173285a8d7341e5e972fc677286384f802f8ef42a5ec5f03bbfa254cb01fad000000000000000000000000000000000000000000000000000000000000001b0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001b").unwrap();
+	let mut o = [255u8; 32];
+	f(&i_bad[..], &mut o[..]);
+	assert_eq!(&o[..], &(FromHex::from_hex("ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff").unwrap())[..]);
+
+	let i_bad = FromHex::from_hex("47173285a8d7341e5e972fc677286384f802f8ef42a5ec5f03bbfa254cb01fad000000000000000000000000000000000000000000000000000000000000001bffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff000000000000000000000000000000000000000000000000000000000000001b").unwrap();
+	let mut o = [255u8; 32];
+	f(&i_bad[..], &mut o[..]);
+	assert_eq!(&o[..], &(FromHex::from_hex("ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff").unwrap())[..]);
+
+	let i_bad = FromHex::from_hex("47173285a8d7341e5e972fc677286384f802f8ef42a5ec5f03bbfa254cb01fad000000000000000000000000000000000000000000000000000000000000001b000000000000000000000000000000000000000000000000000000000000001bffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff").unwrap();
+	let mut o = [255u8; 32];
+	f(&i_bad[..], &mut o[..]);
+	assert_eq!(&o[..], &(FromHex::from_hex("ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff").unwrap())[..]);
+
+	// TODO: Should this (corrupted version of the above) fail rather than returning some address?
+/*	let i_bad = FromHex::from_hex("48173285a8d7341e5e972fc677286384f802f8ef42a5ec5f03bbfa254cb01fad000000000000000000000000000000000000000000000000000000000000001b650acf9d3f5f0a2c799776a1254355d5f4061762a237396a99a0e0e3fc2bcd6729514a0dacb2e623ac4abd157cb18163ff942280db4d5caad66ddf941ba12e03").unwrap();
+	let mut o = [255u8; 32];
+	f(&i_bad[..], &mut o[..]);
+	assert_eq!(&o[..], &(FromHex::from_hex("ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff").unwrap())[..]);*/
+}
+
+#[test]
+fn from_named_linear() {
+	let b = Builtin::from_named_linear("identity", 10, 20).unwrap();
+	assert_eq!((*b.cost)(0), U256::from(10));
+	assert_eq!((*b.cost)(1), U256::from(30));
+	assert_eq!((*b.cost)(32), U256::from(30));
+	assert_eq!((*b.cost)(33), U256::from(50));
+
+	let i = [0u8, 1, 2, 3];
+	let mut o = [255u8; 4];
+	(*b.execute)(&i[..], &mut o[..]);
+	assert_eq!(i, o);
+}
+
+#[test]
+fn from_json() {
+	let text = "{ \"name\": \"identity\", \"linear\": {\"base\": 10, \"word\": 20} }";
+	let json = Json::from_str(text).unwrap();
+	let b = Builtin::from_json(&json).unwrap();
+	assert_eq!((*b.cost)(0), U256::from(10));
+	assert_eq!((*b.cost)(1), U256::from(30));
+	assert_eq!((*b.cost)(32), U256::from(30));
+	assert_eq!((*b.cost)(33), U256::from(50));
+
+	let i = [0u8, 1, 2, 3];
+	let mut o = [255u8; 4];
+	(*b.execute)(&i[..], &mut o[..]);
+	assert_eq!(i, o);
+}
--- a/src/engine.rs
+++ b/src/engine.rs
@ -1,11 +1,13 @@
 use std::collections::hash_map::*;
 use util::bytes::*;
+use util::hash::*;
 use util::uint::*;
 use util::rlp::*;
 use util::semantic_version::*;
 use util::error::*;
 use header::Header;
 use transaction::Transaction;
+use block::Block;
 use spec::Spec;
 use evm_schedule::EvmSchedule;
 use env_info::EnvInfo;
@ -34,19 +36,17 @@ pub trait Engine {

 	/// Some intrinsic operation parameters; by default they take their value from the `spec()`'s `engine_params`.
 	fn maximum_extra_data_size(&self, _env_info: &EnvInfo) -> usize { decode(&self.spec().engine_params.get("maximum_extra_data_size").unwrap()) }
-	fn account_start_nonce(&self, _env_info: &EnvInfo) -> U256 { decode(&self.spec().engine_params.get("account_start_nonce").unwrap()) }
-	// TODO: refactor in terms of `on_preseal_block`
-	fn block_reward(&self, _env_info: &EnvInfo) -> U256 { decode(&self.spec().engine_params.get("block_reward").unwrap()) }
+	fn account_start_nonce(&self) -> U256 { decode(&self.spec().engine_params.get("account_start_nonce").unwrap()) }

 	/// Block transformation functions, before and after the transactions.
-//	fn on_new_block(&self, _env_info: &EnvInfo, _block: &mut Block) -> Result<(), EthcoreError> {}
-//	fn on_preseal_block(&self, _env_info: &EnvInfo, _block: &mut Block) -> Result<(), EthcoreError> {}
+	fn on_new_block(&self, _block: &mut Block) {}
+	fn on_close_block(&self, _block: &mut Block) {}

 	/// Verify that `header` is valid.
 	/// `parent` (the parent header) and `block` (the header's full block) may be provided for additional
 	/// checks. Returns either a null `Ok` or a general error detailing the problem with import.
 	// TODO: consider including State in the params.
-	fn verify(&self, _header: &Header, _parent: Option<&Header>, _block: Option<&[u8]>) -> Result<(), EthcoreError> { Ok(()) }
+	fn verify_block(&self, _header: &Header, _parent: Option<&Header>, _block: Option<&[u8]>) -> Result<(), EthcoreError> { Ok(()) }

 	/// Additional verification for transactions in blocks.
 	// TODO: Add flags for which bits of the transaction to check.
@ -55,14 +55,13 @@ pub trait Engine {

 	/// Don't forget to call Super::populateFromParent when subclassing & overriding.
 	// TODO: consider including State in the params.
-	fn populate_from_parent(&self, _header: &mut Header, _parent: &Header) -> Result<(), EthcoreError> { Ok(()) }
+	fn populate_from_parent(&self, _header: &mut Header, _parent: &Header) {}

-	// TODO: buildin contract routing - to do this properly, it will require removing the built-in configuration-reading logic
+	// TODO: builtin contract routing - to do this properly, it will require removing the built-in configuration-reading logic
 	// from Spec into here and removing the Spec::builtins field.
-/*	fn is_builtin(&self, a: Address) -> bool;
-	fn cost_of_builtin(&self, a: Address, in: &[u8]) -> bignum;
-	fn execute_builtin(&self, a: Address, in: &[u8], out: &mut [u8]);
-*/
+	fn is_builtin(&self, a: &Address) -> bool { self.spec().builtins.contains_key(a) }
+	fn cost_of_builtin(&self, a: &Address, input: &[u8]) -> U256 { self.spec().builtins.get(a).unwrap().cost(input.len()) }
+	fn execute_builtin(&self, a: &Address, input: &[u8], output: &mut [u8]) { self.spec().builtins.get(a).unwrap().execute(input, output); }

 	// TODO: sealing stuff - though might want to leave this for later.
 }
--- a/src/ethash.rs
+++ b/src/ethash.rs
@ -0,0 +1,33 @@
+//use util::error::*;
+use util::rlp::decode;
+use engine::Engine;
+use spec::Spec;
+use block::*;
+use evm_schedule::EvmSchedule;
+use env_info::EnvInfo;
+
+/// Engine using Ethash proof-of-work consensus algorithm, suitable for Ethereum
+/// mainnet chains in the Olympic, Frontier and Homestead eras.
+pub struct Ethash {
+	spec: Spec,
+}
+
+impl Ethash {
+	pub fn new_boxed(spec: Spec) -> Box<Engine> {
+		Box::new(Ethash{spec: spec})
+	}
+}
+
+impl Engine for Ethash {
+	fn name(&self) -> &str { "Ethash" }
+	fn spec(&self) -> &Spec { &self.spec }
+	fn evm_schedule(&self, _env_info: &EnvInfo) -> EvmSchedule { EvmSchedule::new_frontier() }
+
+	/// Apply the block reward on finalisation of the block.
+	fn on_close_block(&self, block: &mut Block) {
+		let a = block.header().author.clone();
+		block.state_mut().add_balance(&a, &decode(&self.spec().engine_params.get("block_reward").unwrap()));
+	}
+}
+
+// TODO: test for on_close_block.
--- a/src/genesis.rs
+++ b/src/genesis.rs
@ -90,7 +90,7 @@ impl Genesis {
 				// ethash specific fields
 				let mixhash = H256::from_str(&json["mixhash"].as_string().unwrap()[2..]).unwrap();
 				let nonce = H64::from_str(&json["nonce"].as_string().unwrap()[2..]).unwrap();
-				vec![mixhash.to_vec(), nonce.to_vec()]
+				vec![encode(&mixhash), encode(&nonce)]
 			},
 			hash: RefCell::new(None)
 		};
--- a/src/header.rs
+++ b/src/header.rs
@ -5,12 +5,22 @@ use util::bytes::*;
 use util::uint::*;
 use util::rlp::*;

-pub static ZERO_ADDRESS: Address = Address([0x00; 20]);
-pub static ZERO_H256: H256 = H256([0x00; 32]);
-pub static ZERO_LOGBLOOM: LogBloom = H2048([0x00; 256]);
-
+/// Type for a 2048-bit log-bloom, as used by our blocks.
 pub type LogBloom = H2048;

+/// Constant address for point 0. Often used as a default.
+pub static ZERO_ADDRESS: Address = Address([0x00; 20]);
+/// Constant 256-bit datum for 0. Often used as a default.
+pub static ZERO_H256: H256 = H256([0x00; 32]);
+/// Constant 2048-bit datum for 0. Often used as a default.
+pub static ZERO_LOGBLOOM: LogBloom = H2048([0x00; 256]);
+
+/// A block header.
+///
+/// Reflects the specific RLP fields of a block in the chain with additional room for the seal
+/// which is non-specific.
+///
+/// Doesn't do all that much on its own.
 #[derive(Debug)]
 pub struct Header {
 	pub parent_hash: H256,
@ -35,6 +45,7 @@ pub struct Header {
 }

 impl Header {
+	/// Create a new, default-valued, header.
 	pub fn new() -> Header {
 		Header {
 			parent_hash: ZERO_H256.clone(),
@ -121,11 +132,33 @@ impl Encodable for Header {
 			self.extra_data.encode(e);

 			for b in self.seal.iter() {
-				b.encode(e);
+				e.emit_raw(&b);
 			}
 		})
 	}
 }
+/*
+trait RlpStandard {
+	fn append(&self, s: &mut RlpStream);
+}
+
+impl RlpStandard for Header {
+	fn append(&self, s: &mut RlpStream) {
+		s.append_list(13);
+		s.append(self.parent_hash);
+		s.append_raw(self.seal[0]);
+		s.append_standard(self.x);
+	}
+	fn populate(&mut self, s: &Rlp) {
+	}
+}
+
+impl RlpStream {
+	fn append_standard<O>(&mut self, o: &O) where O: RlpStandard {
+		o.append(self);
+	}
+}
+*/

 #[cfg(test)]
 mod tests {
--- a/src/lib.rs
+++ b/src/lib.rs
@ -77,6 +77,7 @@ extern crate rustc_serialize;
 extern crate flate2;
 extern crate rocksdb;
 extern crate heapsize;
+extern crate crypto;

 extern crate env_logger;
 #[cfg(feature = "jit" )]
@ -108,4 +109,5 @@ pub mod client;
 pub mod sync;
 pub mod verification;
 pub mod queue;
-
+pub mod ethash;
+pub mod block;
--- a/src/receipt.rs
+++ b/src/receipt.rs
@ -1,7 +1,9 @@
 use util::hash::*;
+use util::uint::*;

 /// Information describing execution of a transaction.
 pub struct Receipt {
 	// TODO
 	pub state_root: H256,
+	pub gas_used: U256,
 }
--- a/src/spec.rs
+++ b/src/spec.rs
@ -17,11 +17,12 @@ use account::*;
 use engine::Engine;
 use builtin::Builtin;
 use null_engine::NullEngine;
+use ethash::Ethash;
 use denominations::*;
 use header::*;

 /// Converts file from base64 gzipped bytes to json
-pub fn base_to_json(source: &[u8]) -> Json {
+pub fn gzip64res_to_json(source: &[u8]) -> Json {
 	// there is probably no need to store genesis in based64 gzip,
 	// but that's what go does, and it was easy to load it this way
 	let data = source.from_base64().expect("Genesis block is malformed!");
@ -34,11 +35,12 @@ pub fn base_to_json(source: &[u8]) -> Json {

 /// Convert JSON value to equivlaent RLP representation.
 // TODO: handle container types.
-pub fn json_to_rlp(json: &Json) -> Bytes {
+fn json_to_rlp(json: &Json) -> Bytes {
 	match json {
+		&Json::Boolean(o) => encode(&(if o {1u64} else {0})),
 		&Json::I64(o) => encode(&(o as u64)),
 		&Json::U64(o) => encode(&o),
-		&Json::String(ref s) if &s[0..2] == "0x" && U256::from_str(&s[2..]).is_ok() => {
+		&Json::String(ref s) if s.len() >= 2 && &s[0..2] == "0x" && U256::from_str(&s[2..]).is_ok() => {
 			encode(&U256::from_str(&s[2..]).unwrap())
 		},
 		&Json::String(ref s) => {
@ -49,7 +51,7 @@ pub fn json_to_rlp(json: &Json) -> Bytes {
 }

 /// Convert JSON to a string->RLP map.
-pub fn json_to_rlp_map(json: &Json) -> HashMap<String, Bytes> {
+fn json_to_rlp_map(json: &Json) -> HashMap<String, Bytes> {
 	json.as_object().unwrap().iter().map(|(k, v)| (k, json_to_rlp(v))).fold(HashMap::new(), |mut acc, kv| {
 		acc.insert(kv.0.clone(), kv.1);
 		acc
@ -58,6 +60,7 @@ pub fn json_to_rlp_map(json: &Json) -> HashMap<String, Bytes> {

 /// Parameters for a block chain; includes both those intrinsic to the design of the
 /// chain and those to be interpreted by the active chain engine.
+#[derive(Debug)]
 pub struct Spec {
 	// What engine are we using for this?
 	pub engine_name: String,
@ -91,6 +94,7 @@ impl Spec {
 	pub fn to_engine(self) -> Result<Box<Engine>, EthcoreError> {
 		match self.engine_name.as_ref() {
 			"NullEngine" => Ok(NullEngine::new_boxed(self)),
+			"Ethash" => Ok(Ethash::new_boxed(self)),
 			_ => Err(EthcoreError::UnknownName)
 		}
 	}
@ -98,25 +102,22 @@ impl Spec {
 	/// Return the state root for the genesis state, memoising accordingly.
 	pub fn state_root(&self) -> Ref<H256> {
 		if self.state_root_memo.borrow().is_none() {
-			*self.state_root_memo.borrow_mut() = Some(trie_root(self.genesis_state.iter().map(|(k, v)| (k.to_vec(), v.rlp())).collect()));
+			*self.state_root_memo.borrow_mut() = Some(sec_trie_root(self.genesis_state.iter().map(|(k, v)| (k.to_vec(), v.rlp())).collect()));
 		}
 		Ref::map(self.state_root_memo.borrow(), |x|x.as_ref().unwrap())
 	}

-	/// Compose the genesis block for this chain.
-	pub fn genesis_block(&self) -> Bytes {
-		let empty_list = RlpStream::new_list(0).out();
-		let empty_list_sha3 = empty_list.sha3();
-		let header = Header {
+	fn genesis_header(&self) -> Header {
+		Header {
 			parent_hash: self.parent_hash.clone(),
 			timestamp: self.timestamp.clone(),
 			number: U256::from(0u8),
 			author: self.author.clone(),
-			transactions_root: SHA3_EMPTY.clone(),
-			uncles_hash: empty_list_sha3.clone(),
+			transactions_root: SHA3_NULL_RLP.clone(),
+			uncles_hash: RlpStream::new_list(0).out().sha3(),
 			extra_data: self.extra_data.clone(),
 			state_root: self.state_root().clone(),
-			receipts_root: SHA3_EMPTY.clone(),
+			receipts_root: SHA3_NULL_RLP.clone(),
 			log_bloom: H2048::new().clone(),
 			gas_used: self.gas_used.clone(),
 			gas_limit: self.gas_limit.clone(),
@ -131,67 +132,94 @@ impl Spec {
 				(0..self.seal_fields).map(|i| r.at(i).as_raw().to_vec()).collect()
 			},
 			hash: RefCell::new(None)
-		};
+		}
+	}
+
+	/// Compose the genesis block for this chain.
+	pub fn genesis_block(&self) -> Bytes {
+		let empty_list = RlpStream::new_list(0).out();
+		let header = self.genesis_header();
 		let mut ret = RlpStream::new_list(3);
 		ret.append(&header);
 		ret.append_raw(&empty_list, 1);
 		ret.append_raw(&empty_list, 1);
 		ret.out()
 	}
-}

-
-impl Spec {
 	/// Loads a chain-specification from a json data structure
 	pub fn from_json(json: Json) -> Spec {
 		// once we commit ourselves to some json parsing library (serde?)
 		// move it to proper data structure
 		let mut state = HashMap::new();
-		let accounts = json["alloc"].as_object().expect("Missing genesis state");
+		let mut builtins = HashMap::new();
+
+		if let Some(&Json::Object(ref accounts)) = json.find("accounts") {
 			for (address, acc) in accounts.iter() {
 				let addr = Address::from_str(address).unwrap();
-			let o = acc.as_object().unwrap();
-			let balance = U256::from_dec_str(o["balance"].as_string().unwrap()).unwrap();
-			state.insert(addr, Account::new_basic(balance, U256::from(0)));
+				if let Some(ref builtin_json) = acc.find("builtin") {
+					if let Some(builtin) = Builtin::from_json(builtin_json) {
+						builtins.insert(addr.clone(), builtin);
+					}
+				}
+				let balance = acc.find("balance").and_then(|x| match x { &Json::String(ref b) => U256::from_dec_str(b).ok(), _ => None });
+				let nonce = acc.find("nonce").and_then(|x| match x { &Json::String(ref b) => U256::from_dec_str(b).ok(), _ => None });
+//				let balance = if let Some(&Json::String(ref b)) = acc.find("balance") {U256::from_dec_str(b).unwrap_or(U256::from(0))} else {U256::from(0)};
+//				let nonce = if let Some(&Json::String(ref n)) = acc.find("nonce") {U256::from_dec_str(n).unwrap_or(U256::from(0))} else {U256::from(0)};
+				// TODO: handle code & data if they exist.
+				if balance.is_some() || nonce.is_some() {
+					state.insert(addr, Account::new_basic(balance.unwrap_or(U256::from(0)), nonce.unwrap_or(U256::from(0))));
+				}
+			}
 		}

-		let builtins = {
-			// TODO: populate from json.
-			HashMap::new()
-		};
+		let genesis = &json["genesis"];//.as_object().expect("No genesis object in JSON");

 		let (seal_fields, seal_rlp) = {
-			if json.find("mixhash").is_some() && json.find("nonce").is_some() {
+			if genesis.find("mixHash").is_some() && genesis.find("nonce").is_some() {
 				let mut s = RlpStream::new();
-				s.append(&H256::from_str(&json["mixhash"].as_string().unwrap()[2..]).unwrap());
-				s.append(&H64::from_str(&json["nonce"].as_string().unwrap()[2..]).unwrap());
+				s.append(&H256::from_str(&genesis["mixHash"].as_string().expect("mixHash not a string.")[2..]).expect("Invalid mixHash string value"));
+				s.append(&H64::from_str(&genesis["nonce"].as_string().expect("nonce not a string.")[2..]).expect("Invalid nonce string value"));
 				(2, s.out())
 			} else {
 				// backup algo that will work with sealFields/sealRlp (and without).
-				(usize::from_str(&json["sealFields"].as_string().unwrap_or("0x")[2..]).unwrap(), json["sealRlp"].as_string().unwrap_or("0x")[2..].from_hex().unwrap())
+				(
+					usize::from_str(&genesis["sealFields"].as_string().unwrap_or("0x")[2..]).expect("Invalid sealFields integer data"),
+					genesis["sealRlp"].as_string().unwrap_or("0x")[2..].from_hex().expect("Invalid sealRlp hex data")
+				)
 			}
 		};

+		
 		Spec {
 			engine_name: json["engineName"].as_string().unwrap().to_string(),
 			engine_params: json_to_rlp_map(&json["params"]),
 			builtins: builtins,
-			parent_hash: H256::from_str(&json["parentHash"].as_string().unwrap()[2..]).unwrap(),
-			author: Address::from_str(&json["coinbase"].as_string().unwrap()[2..]).unwrap(),
-			difficulty: U256::from_str(&json["difficulty"].as_string().unwrap()[2..]).unwrap(),
-			gas_limit: U256::from_str(&json["gasLimit"].as_string().unwrap()[2..]).unwrap(),
+			parent_hash: H256::from_str(&genesis["parentHash"].as_string().unwrap()[2..]).unwrap(),
+			author: Address::from_str(&genesis["author"].as_string().unwrap()[2..]).unwrap(),
+			difficulty: U256::from_str(&genesis["difficulty"].as_string().unwrap()[2..]).unwrap(),
+			gas_limit: U256::from_str(&genesis["gasLimit"].as_string().unwrap()[2..]).unwrap(),
 			gas_used: U256::from(0u8),
-			timestamp: U256::from_str(&json["timestamp"].as_string().unwrap()[2..]).unwrap(),
-			extra_data: json["extraData"].as_string().unwrap()[2..].from_hex().unwrap(),
+			timestamp: U256::from_str(&genesis["timestamp"].as_string().unwrap()[2..]).unwrap(),
+			extra_data: genesis["extraData"].as_string().unwrap()[2..].from_hex().unwrap(),
 			genesis_state: state,
 			seal_fields: seal_fields,
 			seal_rlp: seal_rlp,
-			state_root_memo: RefCell::new(json["stateRoot"].as_string().map(|s| H256::from_str(&s[2..]).unwrap())),
+			state_root_memo: RefCell::new(genesis.find("stateRoot").and_then(|_| genesis["stateRoot"].as_string()).map(|s| H256::from_str(&s[2..]).unwrap())),
 		}
 	}

+	/// Returns the builtins map for the standard network of Ethereum Olympic, Frontier and Homestead.
+	fn standard_builtins() -> HashMap<Address, Builtin> {
+		let mut ret = HashMap::new();
+		ret.insert(Address::from_str("0000000000000000000000000000000000000001").unwrap(), Builtin::from_named_linear("ecrecover", 3000, 0).unwrap());
+		ret.insert(Address::from_str("0000000000000000000000000000000000000002").unwrap(), Builtin::from_named_linear("sha256", 60, 12).unwrap());
+		ret.insert(Address::from_str("0000000000000000000000000000000000000003").unwrap(), Builtin::from_named_linear("ripemd160", 600, 120).unwrap());
+		ret.insert(Address::from_str("0000000000000000000000000000000000000004").unwrap(), Builtin::from_named_linear("identity", 15, 3).unwrap());
+		ret
+	}
+
 	/// Creates the Olympic network chain spec.
-	pub fn olympic() -> Spec {
+	pub fn new_like_olympic() -> Spec {
 		Spec {
 			engine_name: "Ethash".to_string(),
 			engine_params: vec![
@ -208,7 +236,7 @@ impl Spec {
 				acc.insert(vec.0.to_string(), vec.1);
 				acc
 			}),
-			builtins: HashMap::new(),			// TODO: make correct
+			builtins: Self::standard_builtins(),
 			parent_hash: H256::new(),
 			author: Address::new(),
 			difficulty: U256::from(131_072u64),
@ -223,13 +251,13 @@ impl Spec {
 				acc
 			}),
 			seal_fields: 2,
-			seal_rlp: { let mut r = RlpStream::new_list(2); r.append(&0x2au64); r.append(&H256::new()); r.out() },	// TODO: make correct
+			seal_rlp: { let mut r = RlpStream::new_list(2); r.append(&H256::new()); r.append(&0x2au64); r.out() },	// TODO: make correct
 			state_root_memo: RefCell::new(None),
 		}
 	}

-	/// Creates the Frontier network chain spec.
-	pub fn frontier() -> Spec {
+	/// Creates the Frontier network chain spec, except for the genesis state, which is blank.
+	pub fn new_like_frontier() -> Spec {
 		Spec {
 			engine_name: "Ethash".to_string(),
 			engine_params: vec![
@ -246,7 +274,7 @@ impl Spec {
 				acc.insert(vec.0.to_string(), vec.1);
 				acc
 			}),
-			builtins: HashMap::new(),			// TODO: make correct
+			builtins: Self::standard_builtins(),
 			parent_hash: H256::new(),
 			author: Address::new(),
 			difficulty: U256::from(131_072u64),
@ -261,13 +289,13 @@ impl Spec {
 				acc
 			}),
 			seal_fields: 2,
-			seal_rlp: { let mut r = RlpStream::new_list(2); r.append(&0x42u64); r.append(&H256::new()); r.out() },
+			seal_rlp: { let mut r = RlpStream::new_list(2); r.append(&H256::new()); r.append(&0x42u64); r.out() },
 			state_root_memo: RefCell::new(None),
 		}
 	}

-	/// Creates the Morden network chain spec.
-	pub fn morden() -> Spec {
+	/// Creates the actual Morden network chain spec.
+	pub fn new_morden_manual() -> Spec {
 		Spec {
 			engine_name: "Ethash".to_string(),
 			engine_params: vec![
@ -284,24 +312,90 @@ impl Spec {
 				acc.insert(vec.0.to_string(), vec.1);
 				acc
 			}),
-			builtins: HashMap::new(),			// TODO: make correct
+			builtins: Self::standard_builtins(),
 			parent_hash: H256::new(),
 			author: Address::new(),
-			difficulty: U256::from(131_072u64),
-			gas_limit: U256::from(0u64),
+			difficulty: U256::from(0x20000u64),
+			gas_limit: U256::from(0x2fefd8u64),
 			gas_used: U256::from(0u64),
 			timestamp: U256::from(0u64),
 			extra_data: vec![],
-			genesis_state: vec![				// TODO: make correct
-				(Address::new(), Account::new_basic(U256::from(1) << 200, U256::from(0)))
-			].into_iter().fold(HashMap::new(), | mut acc, vec | {
+			genesis_state: {
+				let n = U256::from(1) << 20;
+				vec![
+					(Address::from_str("0000000000000000000000000000000000000001").unwrap(), Account::new_basic(U256::from(1), n)),
+					(Address::from_str("0000000000000000000000000000000000000002").unwrap(), Account::new_basic(U256::from(1), n)),
+					(Address::from_str("0000000000000000000000000000000000000003").unwrap(), Account::new_basic(U256::from(1), n)),
+					(Address::from_str("0000000000000000000000000000000000000004").unwrap(), Account::new_basic(U256::from(1), n)),
+					(Address::from_str("102e61f5d8f9bc71d0ad4a084df4e65e05ce0e1c").unwrap(), Account::new_basic(U256::from(1) << 200, n))
+				]}.into_iter().fold(HashMap::new(), | mut acc, vec | {
 					acc.insert(vec.0, vec.1);
 					acc
 				}),
 			seal_fields: 2,
-			seal_rlp: { let mut r = RlpStream::new_list(2); r.append(&0x00006d6f7264656eu64); r.append(&H256::from_str("00000000000000000000000000000000000000647572616c65787365646c6578").unwrap()); r.out() },	// TODO: make correct
+			seal_rlp: {
+				let mut r = RlpStream::new();
+				r.append(&H256::from_str("00000000000000000000000000000000000000647572616c65787365646c6578").unwrap());
+				r.append(&FromHex::from_hex("00006d6f7264656e").unwrap());
+				r.out()
+			},
 			state_root_memo: RefCell::new(None),
 		}
 	}
+
+	/// Create a new Spec from a JSON UTF-8 data resource `data`.
+	pub fn from_json_utf8(data: &[u8]) -> Spec {
+		Self::from_json_str(::std::str::from_utf8(data).unwrap())
+	}
+
+	/// Create a new Spec from a JSON string.
+	pub fn from_json_str(s: &str) -> Spec {
+		let json = Json::from_str(s).expect("Json is invalid");
+		Self::from_json(json)
+	}
+
+	/// Create a new Morden chain spec.
+	pub fn new_morden() -> Spec { Self::from_json_utf8(include_bytes!("../res/morden.json")) }
+
+	/// Create a new Frontier chain spec.
+	pub fn new_frontier() -> Spec { Self::from_json_utf8(include_bytes!("../res/frontier.json")) }
 }

+#[cfg(test)]
+mod tests {
+	use std::str::FromStr;
+	use util::hash::*;
+	use util::sha3::*;
+	use rustc_serialize::json::Json;
+	use views::*;
+	use super::*;
+
+	#[test]
+	fn morden_manual() {
+		let morden = Spec::new_morden_manual();
+
+		assert_eq!(*morden.state_root(), H256::from_str("f3f4696bbf3b3b07775128eb7a3763279a394e382130f27c21e70233e04946a9").unwrap());
+		let genesis = morden.genesis_block();
+		assert_eq!(BlockView::new(&genesis).header_view().sha3(), H256::from_str("0cd786a2425d16f152c658316c423e6ce1181e15c3295826d7c9904cba9ce303").unwrap());
+	}
+
+	#[test]
+	fn morden() {
+		let morden = Spec::new_morden();
+
+		assert_eq!(*morden.state_root(), H256::from_str("f3f4696bbf3b3b07775128eb7a3763279a394e382130f27c21e70233e04946a9").unwrap());
+		let genesis = morden.genesis_block();
+		assert_eq!(BlockView::new(&genesis).header_view().sha3(), H256::from_str("0cd786a2425d16f152c658316c423e6ce1181e15c3295826d7c9904cba9ce303").unwrap());
+	}
+
+	#[test]
+	fn frontier() {
+		let frontier = Spec::new_frontier();
+
+		assert_eq!(*frontier.state_root(), H256::from_str("d7f8974fb5ac78d9ac099b9ad5018bedc2ce0a72dad1827a1709da30580f0544").unwrap());
+		let genesis = frontier.genesis_block();
+		assert_eq!(BlockView::new(&genesis).header_view().sha3(), H256::from_str("d4e56740f876aef8c010b86a40d5f56745a118d0906a34e69aec8c0db1cb8fa3").unwrap());
+
+		let engine = frontier.to_engine();
+	}
+}
--- a/src/state.rs
+++ b/src/state.rs
@ -8,6 +8,7 @@ use util::trie::*;
 use util::bytes::*;
 use util::rlp::*;
 use util::uint::*;
+use util::error::*;
 use account::Account;
 use transaction::Transaction;
 use receipt::Receipt;
@ -15,7 +16,11 @@ use env_info::EnvInfo;
 use engine::Engine;

 /// Information concerning the result of the `State::apply` operation.
-pub struct ApplyResult;	// TODO
+pub struct ApplyInfo {
+	pub receipt: Receipt,
+}
+
+pub type ApplyResult = Result<ApplyInfo, EthcoreError>;

 /// Representation of the entire state of all accounts in the system.
 pub struct State {
@ -44,7 +49,7 @@ impl State {
 	}

 	/// Creates new state with existing state root
-	pub fn new_existing(mut db: OverlayDB, mut root: H256, account_start_nonce: U256) -> State {
+	pub fn from_existing(mut db: OverlayDB, mut root: H256, account_start_nonce: U256) -> State {
 		{
 			// trie should panic! if root does not exist
 			let _ = TrieDB::new(&mut db, &mut root);
@ -131,7 +136,7 @@ impl State {

 	/// Execute a given transaction.
 	/// This will change the state accordingly.
-	pub fn apply(_env_info: &EnvInfo, _engine: &Engine, _t: &Transaction, _is_permanent: bool) -> (ApplyResult, Receipt) {
+	pub fn apply(&mut self, _env_info: &EnvInfo, _engine: &Engine, _t: &Transaction, _is_permanent: bool) -> ApplyResult {
 		unimplemented!();
 	}

@ -156,7 +161,7 @@ impl State {
 		}

 		{
-			let mut trie = TrieDBMut::new_existing(db, &mut root);
+			let mut trie = TrieDBMut::from_existing(db, &mut root);
 			for (address, ref a) in accounts.iter() {
 				match a {
 					&&Some(ref account) => trie.insert(address, &account.rlp()),
@ -240,7 +245,7 @@ fn code_from_database() {
 		s.drop()
 	};

-	let s = State::new_existing(db, r, U256::from(0u8));
+	let s = State::from_existing(db, r, U256::from(0u8));
 	assert_eq!(s.code(&a), Some([1u8, 2, 3].to_vec()));
 }

@ -254,7 +259,7 @@ fn storage_at_from_database() {
 		s.drop()
 	};

-	let s = State::new_existing(db, r, U256::from(0u8));
+	let s = State::from_existing(db, r, U256::from(0u8));
 	assert_eq!(s.storage_at(&a, &H256::from(&U256::from(01u64))), H256::from(&U256::from(69u64)));
 }

@ -270,7 +275,7 @@ fn get_from_database() {
 		s.drop()
 	};

-	let s = State::new_existing(db, r, U256::from(0u8));
+	let s = State::from_existing(db, r, U256::from(0u8));
 	assert_eq!(s.balance(&a), U256::from(69u64));
 	assert_eq!(s.nonce(&a), U256::from(1u64));
 }
--- a/src/transaction.rs
+++ b/src/transaction.rs
@ -19,10 +19,16 @@ impl Transaction {
 	pub fn is_contract_creation(&self) -> bool {
 		self.to.is_none()
 	}
+
 	/// Is this transaction meant to send a message?
 	pub fn is_message_call(&self) -> bool {
 		!self.is_contract_creation()
 	}
+
+	/// Get the hash of this transaction.
+	pub fn sha3(&self) -> H256 {
+		unimplemented!();
+	}
 }

 impl Encodable for Transaction {