Merge pull request #72 from gavofyork/verification

Block Verification (no tests yet)

src/block.rs

@@ -142,7 +142,7 @@ impl<'x, 'y> OpenBlock<'x, 'y> {
 	/// that the header itself is actually valid.
 	pub fn push_uncle(&mut self, valid_uncle_header: Header) -> Result<(), BlockError> {
 		if self.block.uncles.len() >= self.engine.maximum_uncle_count() {
-			return Err(BlockError::TooManyUncles);
+			return Err(BlockError::TooManyUncles(OutOfBounds{min: 0, max: self.engine.maximum_uncle_count(), found: self.block.uncles.len()}));
 		}
 		// TODO: check number
 		// TODO: check not a direct ancestor (use last_hashes for that)

src/client.rs

@@ -5,6 +5,7 @@ use error::*;
 use header::BlockNumber;
 use spec::Spec;
 use engine::Engine;
+use queue::BlockQueue;
 
 /// General block status
 pub enum BlockStatus {
@@ -18,9 +19,6 @@ pub enum BlockStatus {
 	Unknown,
 }
 
-/// Result of import block operation.
-pub type ImportResult = Result<(), ImportError>;
-
 /// Information about the blockchain gthered together.
 pub struct BlockChainInfo {
 	/// Blockchain difficulty.
@@ -95,28 +93,30 @@ pub trait BlockChainClient : Sync {
 
 /// Blockchain database client backed by a persistent database. Owns and manages a blockchain and a block queue.
 pub struct Client {
-	chain: Arc<BlockChain>,
+	chain: Arc<RwLock<BlockChain>>,
 	_engine: Arc<Box<Engine>>,
+	queue: BlockQueue,
 }
 
 impl Client {
 	pub fn new(spec: Spec, path: &Path) -> Result<Client, Error> {
-		let chain = Arc::new(BlockChain::new(&spec.genesis_block(), path));
+		let chain = Arc::new(RwLock::new(BlockChain::new(&spec.genesis_block(), path)));
 		let engine = Arc::new(try!(spec.to_engine()));
 		Ok(Client {
 			chain: chain.clone(),
-			_engine: engine,
+			_engine: engine.clone(),
+			queue: BlockQueue::new(chain.clone(), engine.clone()),
 		})
 	}
 }
 
 impl BlockChainClient for Client {
 	fn block_header(&self, hash: &H256) -> Option<Bytes> {
-		self.chain.block(hash).map(|bytes| BlockView::new(&bytes).rlp().at(0).as_raw().to_vec())
+		self.chain.read().unwrap().block(hash).map(|bytes| BlockView::new(&bytes).rlp().at(0).as_raw().to_vec())
 	}
 
 	fn block_body(&self, hash: &H256) -> Option<Bytes> {
-		self.chain.block(hash).map(|bytes| {
+		self.chain.read().unwrap().block(hash).map(|bytes| {
 			let rlp = Rlp::new(&bytes);
 			let mut body = RlpStream::new();
 			body.append_raw(rlp.at(1).as_raw(), 1);
@@ -126,34 +126,34 @@ impl BlockChainClient for Client {
 	}
 
 	fn block(&self, hash: &H256) -> Option<Bytes> {
-		self.chain.block(hash)
+		self.chain.read().unwrap().block(hash)
 	}
 
 	fn block_status(&self, hash: &H256) -> BlockStatus {
-		if self.chain.is_known(&hash) { BlockStatus::InChain } else { BlockStatus::Unknown }
+		if self.chain.read().unwrap().is_known(&hash) { BlockStatus::InChain } else { BlockStatus::Unknown }
 	}
 
 	fn block_header_at(&self, n: BlockNumber) -> Option<Bytes> {
-		self.chain.block_hash(n).and_then(|h| self.block_header(&h))
+		self.chain.read().unwrap().block_hash(n).and_then(|h| self.block_header(&h))
 	}
 
 	fn block_body_at(&self, n: BlockNumber) -> Option<Bytes> {
-		self.chain.block_hash(n).and_then(|h| self.block_body(&h))
+		self.chain.read().unwrap().block_hash(n).and_then(|h| self.block_body(&h))
 	}
 
 	fn block_at(&self, n: BlockNumber) -> Option<Bytes> {
-		self.chain.block_hash(n).and_then(|h| self.block(&h))
+		self.chain.read().unwrap().block_hash(n).and_then(|h| self.block(&h))
 	}
 
 	fn block_status_at(&self, n: BlockNumber) -> BlockStatus {
-		match self.chain.block_hash(n) {
+		match self.chain.read().unwrap().block_hash(n) {
 			Some(h) => self.block_status(&h),
 			None => BlockStatus::Unknown
 		}
 	}
 
 	fn tree_route(&self, from: &H256, to: &H256) -> Option<TreeRoute> {
-		self.chain.tree_route(from.clone(), to.clone())
+		self.chain.read().unwrap().tree_route(from.clone(), to.clone())
 	}
 
 	fn state_data(&self, _hash: &H256) -> Option<Bytes> {
@@ -165,17 +165,7 @@ impl BlockChainClient for Client {
 	}
 
 	fn import_block(&mut self, bytes: &[u8]) -> ImportResult {
-		//TODO: verify block
-		{
-			let block = BlockView::new(bytes);
-			let header = block.header_view();
-			let hash = header.sha3();
-			if self.chain.is_known(&hash) {
-				return Err(ImportError::AlreadyInChain);
-			}
-		}
-		self.chain.insert_block(bytes);
-		Ok(())
+		self.queue.import_block(bytes)
 	}
 
 	fn queue_status(&self) -> BlockQueueStatus {
@@ -188,12 +178,13 @@ impl BlockChainClient for Client {
 	}
 
 	fn chain_info(&self) -> BlockChainInfo {
+		let chain = self.chain.read().unwrap();
 		BlockChainInfo {
-			total_difficulty: self.chain.best_block_total_difficulty(),
-			pending_total_difficulty: self.chain.best_block_total_difficulty(),
-			genesis_hash: self.chain.genesis_hash(),
-			best_block_hash: self.chain.best_block_hash(),
-			best_block_number: From::from(self.chain.best_block_number())
+			total_difficulty: chain.best_block_total_difficulty(),
+			pending_total_difficulty: chain.best_block_total_difficulty(),
+			genesis_hash: chain.genesis_hash(),
+			best_block_hash: chain.best_block_hash(),
+			best_block_number: From::from(chain.best_block_number())
 		}
 	}
 }

src/engine.rs

@@ -33,11 +33,18 @@ pub trait Engine : Sync + Send {
 	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_block(&self, _header: &Header, _parent: Option<&Header>, _block: Option<&[u8]>) -> Result<(), Error> { Ok(()) }
+	// TODO: consider including State in the params for verification functions.
+	/// Phase 1 quick block verification. Only does checks that are cheap. `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.
+	fn verify_block_basic(&self, _header: &Header,  _block: Option<&[u8]>) -> Result<(), Error> { Ok(()) }
+
+	/// Phase 2 verification. Perform costly checks such as transaction signatures. `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.
+	fn verify_block_unordered(&self, _header: &Header, _block: Option<&[u8]>) -> Result<(), Error> { Ok(()) }
+
+	/// Phase 3 verification. Check block information against parent and uncles. `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.
+	fn verify_block_final(&self, _header: &Header, _parent: &Header, _block: Option<&[u8]>) -> Result<(), Error> { Ok(()) }
 
 	/// Additional verification for transactions in blocks.
 	// TODO: Add flags for which bits of the transaction to check.

src/error.rs

@@ -1,6 +1,7 @@
 //! General error types for use in ethcore.
 
 use util::*;
+use header::BlockNumber;
 
 #[derive(Debug)]
 pub struct Mismatch<T: fmt::Debug> {
@@ -17,19 +18,47 @@ pub struct OutOfBounds<T: fmt::Debug> {
 
 #[derive(Debug)]
 pub enum BlockError {
-	TooManyUncles,
+	TooManyUncles(OutOfBounds<usize>),
 	UncleWrongGeneration,
 	ExtraDataOutOfBounds(OutOfBounds<usize>),
 	InvalidSealArity(Mismatch<usize>),
+	TooMuchGasUsed(OutOfBounds<U256>),
+	InvalidUnclesHash(Mismatch<H256>),
+	UncleTooOld(OutOfBounds<BlockNumber>),
+	UncleIsBrother(OutOfBounds<BlockNumber>),
+	UncleInChain(H256),
+	UncleParentNotInChain(H256),
+	InvalidStateRoot,
+	InvalidGasUsed,
+	InvalidTransactionsRoot(Mismatch<H256>),
+	InvalidDifficulty(Mismatch<U256>),
+	InvalidGasLimit(OutOfBounds<U256>),
+	InvalidReceiptsStateRoot,
+	InvalidTimestamp(OutOfBounds<u64>),
+	InvalidLogBloom,
+	InvalidBlockNonce,
+	InvalidParentHash(Mismatch<H256>),
+	InvalidNumber(OutOfBounds<BlockNumber>),
+	UnknownParent(H256),
+	UnknownUncleParent(H256),
 }
 
 #[derive(Debug)]
 pub enum ImportError {
-	Bad(BlockError),
+	Bad(Error),
 	AlreadyInChain,
 	AlreadyQueued,
 }
 
+impl From<Error> for ImportError {
+	fn from(err: Error) -> ImportError {
+		ImportError::Bad(err)
+	}
+}
+
+/// Result of import block operation.
+pub type ImportResult = Result<(), ImportError>;
+
 #[derive(Debug)]
 /// General error type which should be capable of representing all errors in ethcore.
 pub enum Error {

src/ethereum/ethash.rs

@@ -43,6 +43,83 @@ impl Engine for Ethash {
 			fields.state.add_balance(u.author(), &(reward * U256::from((8 + u.number() - current_number) / 8)));
 		}
 	}
+
+
+	fn verify_block_basic(&self, header: &Header,  _block: Option<&[u8]>) -> Result<(), Error> {
+		let min_difficulty = decode(self.spec().engine_params.get("minimumDifficulty").unwrap());
+		if header.difficulty < min_difficulty {
+			return Err(From::from(BlockError::InvalidDifficulty(Mismatch { expected: min_difficulty, found: header.difficulty })))
+		}
+		let min_gas_limit = decode(self.spec().engine_params.get("minGasLimit").unwrap());
+		if header.gas_limit < min_gas_limit {
+			return Err(From::from(BlockError::InvalidGasLimit(OutOfBounds { min: min_gas_limit, max: From::from(0), found: header.gas_limit }))); 
+		}
+		let maximum_extra_data_size = self.maximum_extra_data_size();
+		if header.number != 0 && header.extra_data.len() > maximum_extra_data_size {
+			return Err(From::from(BlockError::ExtraDataOutOfBounds(OutOfBounds { min: 0, max: maximum_extra_data_size, found: header.extra_data.len() }))); 
+		}
+		// TODO: Verify seal (quick)
+		Ok(())
+	}
+
+	fn verify_block_unordered(&self, _header: &Header, _block: Option<&[u8]>) -> Result<(), Error> {
+		// TODO: Verify seal (full)
+		Ok(())
+	}
+
+	fn verify_block_final(&self, header: &Header, parent: &Header, _block: Option<&[u8]>) -> Result<(), Error> {
+		// Check difficulty is correct given the two timestamps.
+		let expected_difficulty = self.calculate_difficuty(header, parent);
+		if header.difficulty != expected_difficulty {
+			return Err(From::from(BlockError::InvalidDifficulty(Mismatch { expected: expected_difficulty, found: header.difficulty })))
+		}
+		let gas_limit_divisor = decode(self.spec().engine_params.get("gasLimitBoundDivisor").unwrap());
+		let min_gas = parent.gas_limit - parent.gas_limit / gas_limit_divisor;
+		let max_gas = parent.gas_limit + parent.gas_limit / gas_limit_divisor;
+		if header.gas_limit <= min_gas || header.gas_limit >= max_gas {
+			return Err(From::from(BlockError::InvalidGasLimit(OutOfBounds { min: min_gas, max: max_gas, found: header.gas_limit }))); 
+		}
+		Ok(())
+	}
+
+	fn verify_transaction(&self, _t: &Transaction, _header: &Header) -> Result<(), Error> { Ok(()) }
+}
+
+impl Ethash {
+	fn calculate_difficuty(&self, header: &Header, parent: &Header) -> U256 {
+		const EXP_DIFF_PERIOD: u64 = 100000;
+		if header.number == 0 {
+			panic!("Can't calculate genesis block difficulty");
+		}
+
+		let min_difficulty = decode(self.spec().engine_params.get("minimumDifficulty").unwrap());
+		let difficulty_bound_divisor = decode(self.spec().engine_params.get("difficultyBoundDivisor").unwrap());
+		let duration_limit: u64 = decode(self.spec().engine_params.get("durationLimit").unwrap());
+		let frontier_limit = decode(self.spec().engine_params.get("frontierCompatibilityModeLimit").unwrap());
+		let mut target = if header.number < frontier_limit {
+			if header.timestamp >= parent.timestamp + duration_limit {
+				parent.difficulty - (parent.difficulty / difficulty_bound_divisor) 
+			} 
+			else {
+				parent.difficulty + (parent.difficulty / difficulty_bound_divisor)
+			}
+		}
+		else {
+			let diff_inc = (header.timestamp - parent.timestamp) / 10;
+			if diff_inc <= 1 {
+				parent.difficulty + parent.difficulty / From::from(2048) * From::from(1 - diff_inc)
+			}
+			else {
+				parent.difficulty - parent.difficulty / From::from(2048) * From::from(max(diff_inc - 1, 99))
+			}
+		};
+		target = max(min_difficulty, target);
+		let period = ((parent.number + 1) / EXP_DIFF_PERIOD) as usize;
+		if period > 1 {
+			target = max(min_difficulty, target + (U256::from(1) << (period - 2)));
+		}
+		target
+	}
 }
 
 #[test]
@@ -57,3 +134,5 @@ fn on_close_block() {
 	let b = b.close();
 	assert_eq!(b.state().balance(&Address::zero()), U256::from_str("4563918244f40000").unwrap());
 }
+
+// TODO: difficulty test

src/lib.rs

@@ -106,4 +106,6 @@ pub mod extras;
 pub mod client;
 pub mod sync;
 pub mod block;
+pub mod verification;
+pub mod queue;
 pub mod ethereum;

src/queue.rs

@@ -1,35 +1,41 @@
-use std::sync::Arc;
 use util::*;
 use blockchain::BlockChain;
-use client::{QueueStatus, ImportResult};
 use views::{BlockView};
+use verification::*;
+use error::*;
+use engine::Engine;
 
 /// A queue of blocks. Sits between network or other I/O and the BlockChain.
 /// Sorts them ready for blockchain insertion.
-pub struct BlockQueue;
+pub struct BlockQueue {
+	bc: Arc<RwLock<BlockChain>>,
+	engine: Arc<Box<Engine>>,
+}
 
 impl BlockQueue {
 	/// Creates a new queue instance.
-	pub fn new() -> BlockQueue {
+	pub fn new(bc: Arc<RwLock<BlockChain>>, engine: Arc<Box<Engine>>) -> BlockQueue {
+		BlockQueue {
+			bc: bc,
+			engine: engine,
+		}
 	}
 
 	/// Clear the queue and stop verification activity.
 	pub fn clear(&mut self) {
 	}
 
 	/// Add a block to the queue.
-	pub fn import_block(&mut self, bytes: &[u8], bc: &mut BlockChain) -> ImportResult {
-		//TODO: verify block
-		{
-			let block = BlockView::new(bytes);
-			let header = block.header_view();
-			let hash = header.sha3();
-			if self.chain.is_known(&hash) {
-				return ImportResult::Bad;
-			}
+	pub fn import_block(&mut self, bytes: &[u8]) -> ImportResult {
+		let header = BlockView::new(bytes).header();
+		if self.bc.read().unwrap().is_known(&header.hash()) {
+			return Err(ImportError::AlreadyInChain);
 		}
-		bc.insert_block(bytes);
-		ImportResult::Queued(QueueStatus::Known)
+		try!(verify_block_basic(bytes, self.engine.deref().deref()));
+		try!(verify_block_unordered(bytes, self.engine.deref().deref()));
+		try!(verify_block_final(bytes, self.engine.deref().deref(), self.bc.read().unwrap().deref()));
+		self.bc.write().unwrap().insert_block(bytes);
+		Ok(())
 	}
 }
 

src/sync/tests.rs

@@ -1,13 +1,7 @@
-use std::collections::{HashMap, VecDeque};
-use util::bytes::Bytes;
-use util::hash::{H256, FixedHash};
-use util::uint::{U256};
-use util::sha3::Hashable;
-use util::rlp::{self, Rlp, RlpStream, View, Stream};
-use util::network::{PeerId, PacketId};
-use util::error::UtilError;
-use client::{BlockChainClient, BlockStatus, TreeRoute, BlockQueueStatus, BlockChainInfo, ImportResult};
+use util::*;
+use client::{BlockChainClient, BlockStatus, TreeRoute, BlockQueueStatus, BlockChainInfo};
 use header::{Header as BlockHeader, BlockNumber};
+use error::*;
 use sync::io::SyncIo;
 use sync::chain::ChainSync;