implement provider for client

ethcore/src/client/client.rs

@@ -68,6 +68,7 @@ use factory::Factories;
 use rlp::{decode, View, UntrustedRlp};
 use state_db::StateDB;
 use rand::OsRng;
+use light::{self, request};
 
 // re-export
 pub use types::blockchain_info::BlockChainInfo;
@@ -1317,13 +1318,135 @@ impl MayPanic for Client {
 	}
 }
 
+// Implementation of a light client data provider for a client.
+impl light::Provider for Client {
+	fn chain_info(&self) -> BlockChainInfo {
+		BlockChainClient::chain_info(self)
+	}
+
+	fn reorg_depth(&self, a: &H256, b: &H256) -> Option<u64> {
+		self.tree_route(a, b).map(|route| route.index as u64)
+	}
+
+	fn earliest_state(&self) -> Option<u64> {
+		Some(self.pruning_info().earliest_state)
+	}
+
+	fn block_headers(&self, req: request::Headers) -> Vec<Bytes> {
+		let best_num = self.chain.read().best_block_number();
+		let start_num = req.block_num;
+
+		match self.block_hash(BlockID::Number(req.block_num)) {
+			Some(hash) if hash == req.block_hash => {}
+			_=> {
+				trace!(target: "les_provider", "unknown/non-canonical start block in header request: {:?}", (req.block_num, req.block_hash));
+				return vec![]
+			}
+		}
+
+		(0u64..req.max as u64)
+			.map(|x: u64| x.saturating_mul(req.skip))
+			.take_while(|x| if req.reverse { x < &start_num } else { best_num - start_num < *x })
+			.map(|x| if req.reverse { start_num - x } else { start_num + x })
+			.map(|x| self.block_header(BlockID::Number(x)))
+			.flat_map(|x| x)
+			.fuse() // collect no more beyond the first `None`
+			.collect()
+	}
+
+	fn block_bodies(&self, req: request::Bodies) -> Vec<Bytes> {
+		use ids::BlockID;
+
+		req.block_hashes.into_iter()
+			.map(|hash| self.block_body(BlockID::Hash(hash)))
+			.map(|body| body.unwrap_or_else(|| ::rlp::EMPTY_LIST_RLP.to_vec()))
+			.collect()
+	}
+
+	fn receipts(&self, req: request::Receipts) -> Vec<Bytes> {
+		req.block_hashes.into_iter()
+			.map(|hash| self.block_receipts(&hash))
+			.map(|receipts| receipts.unwrap_or_else(|| ::rlp::EMPTY_LIST_RLP.to_vec()))
+			.collect()
+	}
+
+	fn proofs(&self, req: request::StateProofs) -> Vec<Bytes> {
+		use rlp::{EMPTY_LIST_RLP, RlpStream, Stream};
+
+		let mut results = Vec::with_capacity(req.requests.len());
+
+		for request in req.requests {
+			let state = match self.state_at(BlockID::Hash(request.block)) {
+				Some(state) => state,
+				None => {
+					trace!(target: "light_provider", "state for {} not available", request.block);
+					results.push(EMPTY_LIST_RLP.to_vec());
+					continue;
+				}
+			};
+
+			let res = match request.key2 {
+				Some(storage_key) => state.prove_storage(request.key1, storage_key, request.from_level),
+				None => state.prove_account(request.key1, request.from_level),
+			};
+
+			match res {
+				Ok(records) => {
+					let mut stream = RlpStream::new_list(records.len());
+					for record in records {
+						stream.append_raw(&record, 1);
+					}
+					results.push(stream.out())
+				}
+				Err(e) => {
+					debug!(target: "light_provider", "encountered error {} while forming proof of state at {}", e, request.block);
+					results.push(EMPTY_LIST_RLP.to_vec());
+				}
+			}
+		}
+
+		results
+	}
+
+	fn contract_code(&self, req: request::ContractCodes) -> Vec<Bytes> {
+		req.code_requests.into_iter()
+			.map(|req| {
+				self.state_at(BlockID::Hash(req.block_hash))
+					.map(|state| {
+						match state.code_by_address_hash(req.account_key) {
+							Ok(code) => code.unwrap_or_else(Vec::new),
+							Err(e) => {
+								debug!(target: "light_provider", "encountered error {} while fetching code.", e);
+								Vec::new()
+							}
+						}
+					}).unwrap_or_else(Vec::new)
+			})
+			.collect()
+	}
+
+	fn header_proofs(&self, req: request::HeaderProofs) -> Vec<Bytes> {
+		req.requests.into_iter().map(|_| ::rlp::EMPTY_LIST_RLP.to_vec()).collect()
+	}
+
+	fn pending_transactions(&self) -> Vec<SignedTransaction> {
+		BlockChainClient::pending_transactions(self)
+	}
+}
+
+#[cfg(test)]
+mod tests {
 
 	#[test]
 	fn should_not_cache_details_before_commit() {
+		use client::BlockChainClient;
 		use tests::helpers::*;
+
 		use std::thread;
 		use std::time::Duration;
+		use std::sync::Arc;
 		use std::sync::atomic::{AtomicBool, Ordering};
+		use util::kvdb::DBTransaction;
 
 		let client = generate_dummy_client(0);
 		let genesis = client.chain_info().best_block_hash;
@@ -1346,3 +1469,4 @@ fn should_not_cache_details_before_commit() {
 
 		assert!(client.tree_route(&genesis, &new_hash).is_none());
 	}
+}

ethcore/src/light/client.rs

@@ -101,7 +101,7 @@ impl Provider for Client {
 		Vec::new()
 	}
 
-	fn code(&self, _req: request::ContractCodes) -> Vec<Bytes> {
+	fn contract_code(&self, _req: request::ContractCodes) -> Vec<Bytes> {
 		Vec::new()
 	}
 

ethcore/src/light/mod.rs

@@ -35,4 +35,5 @@ pub mod client;
 pub mod net;
 pub mod provider;
 
+pub use self::provider::Provider;
 pub use types::les_request as request;

ethcore/src/light/provider.rs

@@ -17,11 +17,9 @@
 //! A provider for the LES protocol. This is typically a full node, who can
 //! give as much data as necessary to its peers.
 
-use client::BlockChainClient;
 use transaction::SignedTransaction;
 use blockchain_info::BlockChainInfo;
 
-use rlp::EMPTY_LIST_RLP;
 use util::{Bytes, H256};
 
 use light::request;
@@ -65,7 +63,7 @@ pub trait Provider: Send + Sync {
 	fn proofs(&self, req: request::StateProofs) -> Vec<Bytes>;
 
 	/// Provide contract code for the specified (block_hash, account_hash) pairs.
-	fn code(&self, req: request::ContractCodes) -> Vec<Bytes>;
+	fn contract_code(&self, req: request::ContractCodes) -> Vec<Bytes>;
 
 	/// Provide header proofs from the Canonical Hash Tries.
 	fn header_proofs(&self, req: request::HeaderProofs) -> Vec<Bytes>;
@@ -73,57 +71,3 @@ pub trait Provider: Send + Sync {
 	/// Provide pending transactions.
 	fn pending_transactions(&self) -> Vec<SignedTransaction>;
 }
-
-// TODO [rob] move into trait definition file after ethcore crate
-// is split up. ideally `ethcore-light` will be between `ethcore-blockchain`
-// and `ethcore-client`
-impl<T: BlockChainClient + ?Sized> Provider for T {
-	fn chain_info(&self) -> BlockChainInfo {
-		BlockChainClient::chain_info(self)
-	}
-
-	fn reorg_depth(&self, a: &H256, b: &H256) -> Option<u64> {
-		self.tree_route(a, b).map(|route| route.index as u64)
-	}
-
-	fn earliest_state(&self) -> Option<u64> {
-		Some(self.pruning_info().earliest_state)
-	}
-
-	fn block_headers(&self, req: request::Headers) -> Vec<Bytes> {
-		unimplemented!()
-	}
-
-	fn block_bodies(&self, req: request::Bodies) -> Vec<Bytes> {
-		use ids::BlockID;
-
-		req.block_hashes.into_iter()
-			.map(|hash| self.block_body(BlockID::Hash(hash)))
-			.map(|body| body.unwrap_or_else(|| EMPTY_LIST_RLP.to_vec()))
-			.collect()
-	}
-
-	fn receipts(&self, req: request::Receipts) -> Vec<Bytes> {
-		req.block_hashes.into_iter()
-			.map(|hash| self.block_receipts(&hash))
-			.map(|receipts| receipts.unwrap_or_else(|| EMPTY_LIST_RLP.to_vec()))
-			.collect()
-	}
-
-	fn proofs(&self, req: request::StateProofs) -> Vec<Bytes> {
-		unimplemented!()
-	}
-
-	fn code(&self, req: request::ContractCodes) -> Vec<Bytes> {
-		unimplemented!()
-	}
-
-	fn header_proofs(&self, req: request::HeaderProofs) -> Vec<Bytes> {
-		// TODO: [rob] implement CHT stuff on `ethcore` side.
-		req.requests.into_iter().map(|_| EMPTY_LIST_RLP.to_vec()).collect()
-	}
-
-	fn pending_transactions(&self) -> Vec<SignedTransaction> {
-		unimplemented!()
-	}
-}

ethcore/src/state/account.rs

@@ -437,6 +437,27 @@ impl Account {
 	}
 }
 
+// light client storage proof.
+impl Account {
+	/// Prove a storage key's existence or nonexistence in the account's storage
+	/// trie.
+	/// `storage_key` is the hash of the desired storage key, meaning
+	/// this will only work correctly under a secure trie.
+	/// Returns a merkle proof of the storage trie node with all nodes before `from_level`
+	/// omitted.
+	pub fn prove_storage(&self, db: &HashDB, storage_key: H256, from_level: u32) -> Result<Vec<Bytes>, Box<TrieError>> {
+		use util::trie::{Trie, TrieDB};
+		use util::trie::recorder::{Recorder, BasicRecorder as TrieRecorder};
+
+		let mut recorder = TrieRecorder::with_depth(from_level);
+
+		let trie = try!(TrieDB::new(db, &self.storage_root));
+		let _ = try!(trie.get_recorded(&storage_key, &mut recorder));
+
+		Ok(recorder.drain().into_iter().map(|r| r.data).collect())
+	}
+}
+
 impl fmt::Debug for Account {
 	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 		write!(f, "{:?}", PodAccount::from_account(self))

ethcore/src/state/mod.rs

@@ -16,7 +16,7 @@
 
 use std::cell::{RefCell, RefMut};
 use std::collections::hash_map::Entry;
-use util::*;
+
 use receipt::Receipt;
 use engines::Engine;
 use env_info::EnvInfo;
@@ -30,6 +30,9 @@ use types::state_diff::StateDiff;
 use transaction::SignedTransaction;
 use state_db::StateDB;
 
+use util::*;
+use util::trie::recorder::{Recorder, BasicRecorder as TrieRecorder};
+
 mod account;
 mod substate;
 
@@ -751,6 +754,53 @@ impl State {
 	}
 }
 
+// LES state proof implementations.
+impl State {
+	/// Prove an account's existence or nonexistence in the state trie.
+	/// Returns a merkle proof of the account's trie node with all nodes before `from_level`
+	/// omitted or an encountered trie error.
+	/// Requires a secure trie to be used for accurate results.
+	/// `account_key` == sha3(address)
+	pub fn prove_account(&self, account_key: H256, from_level: u32) -> Result<Vec<Bytes>, Box<TrieError>> {
+		let mut recorder = TrieRecorder::with_depth(from_level);
+		let trie = try!(TrieDB::new(self.db.as_hashdb(), &self.root));
+		let _  = try!(trie.get_recorded(&account_key, &mut recorder));
+
+		Ok(recorder.drain().into_iter().map(|r| r.data).collect())
+	}
+
+	/// Prove an account's storage key's existence or nonexistence in the state.
+	/// Returns a merkle proof of the account's storage trie with all nodes before
+	/// `from_level` omitted. Requires a secure trie to be used for correctness.
+	/// `account_key` == sha3(address)
+	/// `storage_key` == sha3(key)
+	pub fn prove_storage(&self, account_key: H256, storage_key: H256, from_level: u32) -> Result<Vec<Bytes>, Box<TrieError>> {
+		// TODO: probably could look into cache somehow but it's keyed by
+		// address, not sha3(address).
+		let trie = try!(TrieDB::new(self.db.as_hashdb(), &self.root));
+		let acc = match try!(trie.get(&account_key)) {
+			Some(rlp) => Account::from_rlp(&rlp),
+			None => return Ok(Vec::new()),
+		};
+
+		let account_db = self.factories.accountdb.readonly(self.db.as_hashdb(), account_key);
+		acc.prove_storage(account_db.as_hashdb(), storage_key, from_level)
+	}
+
+	/// Get code by address hash.
+	/// Only works when backed by a secure trie.
+	pub fn code_by_address_hash(&self, account_key: H256) -> Result<Option<Bytes>, Box<TrieError>> {
+		let trie = try!(TrieDB::new(self.db.as_hashdb(), &self.root));
+		let mut acc = match try!(trie.get(&account_key)) {
+			Some(rlp) => Account::from_rlp(&rlp),
+			None => return Ok(None),
+		};
+
+		let account_db = self.factories.accountdb.readonly(self.db.as_hashdb(), account_key);
+		Ok(acc.cache_code(account_db.as_hashdb()).map(|c| (&*c).clone()))
+	}
+}
+
 impl fmt::Debug for State {
 	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 		write!(f, "{:?}", self.cache.borrow())

ethcore/src/types/les_request.rs

@@ -29,7 +29,7 @@ pub struct Headers {
 	/// The maximum amount of headers which can be returned.
 	pub max: usize,
 	/// The amount of headers to skip between each response entry.
-	pub skip: usize,
+	pub skip: u64,
 	/// Whether the headers should proceed in falling number from the initial block.
 	pub reverse: bool,
 }

util/src/trie/mod.rs

@@ -97,11 +97,11 @@ pub trait Trie {
 	}
 
 	/// Query the value of the given key in this trie while recording visited nodes
-	/// to the given recorder. If the query fails, the nodes passed to the recorder are unspecified.
+	/// to the given recorder. If the query encounters an error, the nodes passed to the recorder are unspecified.
 	fn get_recorded<'a, 'b, R: 'b>(&'a self, key: &'b [u8], rec: &'b mut R) -> Result<Option<DBValue>>
 		where 'a: 'b, R: Recorder;
 
-	/// Returns an iterator over elements of trie.
+	/// Returns a depth-first iterator over the elements of the trie.
 	fn iter<'a>(&'a self) -> Result<Box<Iterator<Item = TrieItem> + 'a>>;
 }
 

util/src/trie/recorder.rs

@@ -35,7 +35,6 @@ pub struct Record {
 /// These are used to record which nodes are visited during a trie query.
 /// Inline nodes are not to be recorded, as they are contained within their parent.
 pub trait Recorder {
-
 	/// Record that the given node has been visited.
 	///
 	/// The depth parameter is the depth of the visited node, with the root node having depth 0.
@@ -58,6 +57,7 @@ impl Recorder for NoOp {
 
 /// A simple recorder. Does nothing fancy but fulfills the `Recorder` interface
 /// properly.
+#[derive(Debug)]
 pub struct BasicRecorder {
 	nodes: Vec<Record>,
 	min_depth: u32,