beginnings of on_demand request module + verification

ethcore/light/src/net/mod.rs

@@ -192,12 +192,12 @@ pub trait Handler: Send + Sync {
 	fn on_block_headers(&self, _ctx: &EventContext, _req_id: ReqId, _headers: &[Bytes]) { }
 	/// Called when a peer responds with block receipts.
 	fn on_receipts(&self, _ctx: &EventContext, _req_id: ReqId, _receipts: &[Vec<Receipt>]) { }
-	/// Called when a peer responds with state proofs. Each proof is a series of trie
+	/// Called when a peer responds with state proofs. Each proof should be a series of trie
 	/// nodes in ascending order by distance from the root.
 	fn on_state_proofs(&self, _ctx: &EventContext, _req_id: ReqId, _proofs: &[Vec<Bytes>]) { }
 	/// Called when a peer responds with contract code.
 	fn on_code(&self, _ctx: &EventContext, _req_id: ReqId, _codes: &[Bytes]) { }
-	/// Called when a peer responds with header proofs. Each proof is a block header coupled
+	/// Called when a peer responds with header proofs. Each proof should be a block header coupled
 	/// with a series of trie nodes is ascending order by distance from the root.
 	fn on_header_proofs(&self, _ctx: &EventContext, _req_id: ReqId, _proofs: &[(Bytes, Vec<Bytes>)]) { }
 	/// Called to "tick" the handler periodically.

ethcore/light/src/on_demand/mod.rs

@@ -29,7 +29,9 @@ use network::PeerId;
 
 use net::{Handler, Status, Capabilities, Announcement, EventContext, BasicContext, ReqId};
 use util::{Address, H256, U256, RwLock};
-use request::{self as les_request, Request as LesRequest};
+use types::les_request::{self as les_request, Request as LesRequest};
+
+pub mod request;
 
 /// Basic account data.
 // TODO: [rob] unify with similar struct in `snapshot`.
@@ -85,14 +87,13 @@ struct Peer {
 	capabilities: Capabilities,
 }
 
-// request info and where to send the result.
-enum Request {
-	HeaderByNumber(u64, H256, Sender<encoded::Header>), // num + CHT root
-	HeaderByHash(H256, Sender<encoded::Header>),
-	Block(encoded::Header, H256, Sender<encoded::Block>),
-	BlockReceipts(encoded::Header, Sender<Vec<Receipt>>),
-	Account(encoded::Header, Address, Sender<Account>),
-	Storage(encoded::Header, Address, H256, Sender<H256>),
+// Attempted request info and sender to put received value.
+enum Attempted {
+	HeaderByNumber(request::HeaderByNumber, Sender<encoded::Header>), // num + CHT root
+	HeaderByHash(request::HeaderByHash, Sender<encoded::Header>),
+	Block(request::Block, Sender<encoded::Block>),
+	BlockReceipts(request::BlockReceipts, Sender<Vec<Receipt>>),
+	Account(request::Account, Sender<Account>),
 }
 
 /// On demand request service. See module docs for more details.
@@ -103,36 +104,11 @@ pub struct OnDemand {
 	pending_requests: RwLock<HashMap<ReqId, Request>>,
 }
 
-impl Handler for OnDemand {
-	fn on_connect(&self, ctx: &EventContext, status: &Status, capabilities: &Capabilities) {
-		self.peers.write().insert(ctx.peer(), Peer { status: status.clone(), capabilities: capabilities.clone() });
-	}
-
-	fn on_disconnect(&self, ctx: &EventContext, unfulfilled: &[ReqId]) {
-		self.peers.write().remove(&ctx.peer());
-
-		for unfulfilled in unfulfilled {
-			if let Some(pending) = self.pending_requests.write().remove(unfulfilled) {
-				trace!(target: "on_demand", "Attempting to reassign dropped request");
-				self.dispatch_request(ctx.as_basic(), pending);
-			}
-		}
-	}
-
-	fn on_announcement(&self, ctx: &EventContext, announcement: &Announcement) {
-		let mut peers = self.peers.write();
-		if let Some(ref mut peer) = peers.get_mut(&ctx.peer()) {
-			peer.status.update_from(&announcement);
-			peer.capabilities.update_from(&announcement);
-		}
-	}
-}
-
 impl OnDemand {
 	/// Request a header by block number and CHT root hash.
 	pub fn header_by_number(&self, ctx: &BasicContext, num: u64, cht_root: H256) -> Response<encoded::Header> {
 		let (sender, receiver) = oneshot::channel();
-		self.dispatch_request(ctx, Request::HeaderByNumber(num, cht_root, sender));
+		self.dispatch_request(ctx, Pending::HeaderByNumber(num, cht_root, sender));
 		Response(receiver)
 	}
 
@@ -141,7 +117,7 @@ impl OnDemand {
 	/// it as easily.
 	pub fn header_by_hash(&self, ctx: &BasicContext, hash: H256) -> Response<encoded::Header> {
 		let (sender, receiver) = oneshot::channel();
-		self.dispatch_request(ctx, Request::HeaderByHash(hash, sender));
+		self.dispatch_request(ctx, Pending::HeaderByHash(hash, sender));
 		Response(receiver)
 	}
 
@@ -151,7 +127,7 @@ impl OnDemand {
 	pub fn block(&self, ctx: &BasicContext, header: encoded::Header) -> Response<encoded::Block> {
 		let (sender, receiver) = oneshot::channel();
 		let hash = header.hash();
-		self.dispatch_request(ctx, Request::Block(header, hash, sender));
+		self.dispatch_request(ctx, Pending::Block(header, hash, sender));
 		Response(receiver)
 	}
 
@@ -159,7 +135,7 @@ impl OnDemand {
 	/// provide the block hash to fetch receipts for, and for verification of the receipts root.
 	pub fn block_receipts(&self, ctx: &BasicContext, header: encoded::Header) -> Response<Vec<Receipt>> {
 		let (sender, receiver) = oneshot::channel();
-		self.dispatch_request(ctx, Request::BlockReceipts(header, sender));
+		self.dispatch_request(ctx, Pending::BlockReceipts(header, sender));
 		Response(receiver)
 	}
 
@@ -167,21 +143,23 @@ impl OnDemand {
 	/// to verify against.
 	pub fn account(&self, ctx: &BasicContext, header: encoded::Header, address: Address) -> Response<Account> {
 		let (sender, receiver) = oneshot::channel();
-		self.dispatch_request(ctx, Request::Account(header, address, sender));
+		self.dispatch_request(ctx, Pending::Account(header, address, sender));
 		Response(receiver)
 	}
 
 	/// Request account storage value by block header, address, and key.
 	pub fn storage(&self, ctx: &BasicContext, header: encoded::Header, address: Address, key: H256) -> Response<H256> {
 		let (sender, receiver) = oneshot::channel();
-		self.dispatch_request(ctx, Request::Storage(header, address, key, sender));
+		self.dispatch_request(ctx, Pending::Storage(header, address, key, sender));
 		Response(receiver)
 	}
 
 	// dispatch a request to a suitable peer.
+	//
+	// TODO: most of this will become obsolete with a PeerSearch utility (#3987)
 	fn dispatch_request(&self, ctx: &BasicContext, request: Request) {
 		match request {
-			Request::HeaderByNumber(num, cht_hash, sender) => {
+			Pending::HeaderByNumber(request::HeaderByNumber(num, cht_hash), sender) => {
 				let cht_num = ::client::cht::block_to_cht_number(num);
 				let req = LesRequest::HeaderProofs(les_request::HeaderProofs {
 					requests: vec![les_request::HeaderProof {
@@ -200,7 +178,7 @@ impl OnDemand {
 								trace!(target: "on_demand", "Assigning request to peer {}", id);
 								self.pending_requests.write().insert(
 									req_id,
-									Request::HeaderByNumber(num, cht_hash, sender)
+									Pending::HeaderByNumber(num, cht_hash, sender)
 								);
 								return
 							},
@@ -214,7 +192,7 @@ impl OnDemand {
 				trace!(target: "on_demand", "No suitable peer for request");
 				sender.complete(Err(Error::NoPeersAvailable));
 			}
-			Request::HeaderByHash(hash, sender) => {
+			Pending::HeaderByHash(hash, sender) => {
 				let req = LesRequest::Headers(les_request::Headers {
 					start: hash.into(),
 					max: 1,
@@ -251,7 +229,7 @@ impl OnDemand {
 				trace!(target: "on_demand", "No suitable peer for request");
 				sender.complete(Err(Error::NoPeersAvailable));
 			}
-			Request::Block(header, hash, sender) => {
+			Pending::Block(header, hash, sender) => {
 				let num = header.number();
 				let req = LesRequest::Bodies(les_request::Bodies {
 					block_hashes: vec![hash],
@@ -279,7 +257,7 @@ impl OnDemand {
 				trace!(target: "on_demand", "No suitable peer for request");
 				sender.complete(Err(Error::NoPeersAvailable));
 			}
-			Request::BlockReceipts(header, sender) => {
+			Pending::BlockReceipts(header, sender) => {
 				let num = header.number();
 				let req = LesRequest::Receipts(les_request::Receipts {
 					block_hashes: vec![header.hash()],
@@ -307,7 +285,7 @@ impl OnDemand {
 				trace!(target: "on_demand", "No suitable peer for request");
 				sender.complete(Err(Error::NoPeersAvailable));
 			}
-			Request::Account(header, address, sender) => {
+			Pending::Account(header, address, sender) => {
 				let num = header.number();
 				let req = LesRequest::StateProofs(les_request::StateProofs {
 					requests: vec![les_request::StateProof {
@@ -340,7 +318,7 @@ impl OnDemand {
 				trace!(target: "on_demand", "No suitable peer for request");
 				sender.complete(Err(Error::NoPeersAvailable));
 			}
-			Request::Storage(header, address, key, sender) => {
+			Pending::Storage(header, address, key, sender) => {
 				let num = header.number();
 				let req = LesRequest::StateProofs(les_request::StateProofs {
 					requests: vec![les_request::StateProof {
@@ -376,3 +354,49 @@ impl OnDemand {
 		}
 	}
 }
+
+impl Handler for OnDemand {
+	fn on_connect(&self, ctx: &EventContext, status: &Status, capabilities: &Capabilities) {
+		self.peers.write().insert(ctx.peer(), Peer { status: status.clone(), capabilities: capabilities.clone() });
+	}
+
+	fn on_disconnect(&self, ctx: &EventContext, unfulfilled: &[ReqId]) {
+		self.peers.write().remove(&ctx.peer());
+
+		for unfulfilled in unfulfilled {
+			if let Some(pending) = self.pending_requests.write().remove(unfulfilled) {
+				trace!(target: "on_demand", "Attempting to reassign dropped request");
+				self.dispatch_request(ctx.as_basic(), pending);
+			}
+		}
+	}
+
+	fn on_announcement(&self, ctx: &EventContext, announcement: &Announcement) {
+		let mut peers = self.peers.write();
+		if let Some(ref mut peer) = peers.get_mut(&ctx.peer()) {
+			peer.status.update_from(&announcement);
+			peer.capabilities.update_from(&announcement);
+		}
+	}
+
+	fn on_header_proofs(&self, ctx: &EventContext, req_id: ReqId, proofs: &[(Bytes, Vec<Bytes>)]) {
+		let peer = ctx.peer();
+		let req = match self.pending_requests.write().remove(&req_id) {
+			Some(req) => req,
+			None => return,
+		};
+
+		match req {
+			Request::HeaderByNumber(num, cht_root, sender) => {
+				let (ref header, ref proof) = match proofs.get(0) {
+					Some(ref x) => x,
+					None => {
+						ctx.disconnect_peer(peer);
+						return
+					}
+				};
+			}
+			_ => panic!("Only header by number request fetches header proofs; qed"),
+		}
+	}
+}

ethcore/light/src/on_demand/request.rs

@@ -0,0 +1,158 @@
+use ethcore::encoded;
+use ethcore::receipt::Receipt;
+
+use rlp::{RlpStream, Stream};
+use util::{Address, Bytes, HashDB, H256, U256};
+use util::memorydb::MemoryDB;
+use util::sha3::Hashable;
+use util::trie::{Trie, TrieDB, TrieError};
+
+use super::Account as BasicAccount;
+
+/// Errors in verification.
+#[derive(Debug, PartialEq)]
+pub enum Error {
+	/// RLP decoder error.
+	Decoder(::rlp::DecoderError),
+	/// Trie lookup error (result of bad proof)
+	Trie(TrieError),
+	/// Bad inclusion proof
+	BadProof,
+	/// Wrong header number.
+	WrongNumber(u64, u64),
+	/// Wrong header hash.
+	WrongHash(H256, H256),
+	/// Wrong trie root.
+	WrongTrieRoot(H256, H256),
+}
+
+impl From<::rlp::DecoderError> for Error {
+	fn from(err: ::rlp::DecoderError) -> Self {
+		Error::Decoder(err)
+	}
+}
+
+impl From<Box<TrieError>> for Error {
+	fn from(err: Box<TrieError>) -> Self {
+		Error::Trie(*err)
+	}
+}
+
+/// Request for a header by number.
+pub struct HeaderByNumber {
+	/// The header's number.
+	pub num: u64
+	/// The root of the CHT containing this header.
+	pub cht_root: H256,
+}
+
+impl HeaderByNumber {
+	/// Check a response with a header and cht proof.
+	pub fn check_response(&self, header: &[u8], proof: &[Bytes]) -> Result<encoded::Header, Error> {
+		use util::trie::{Trie, TrieDB};
+		use rlp::{UntrustedRlp, View};
+
+		// check the proof
+		let mut db = MemoryDB::new();
+
+		for node in proof { db.insert(&node[..]) }
+		let key = ::rlp::encode(&self.num);
+
+		let expected_hash: H256 = match TrieDB::new(&db, &self.cht_root).and_then(|t| t.get(&*key))? {
+			Some(val) => ::rlp::decode(&val),
+			None => return Err(Error::BadProof)
+		};
+
+		// and compare the hash to the found header.
+		let found_hash = header.sha3();
+		match expected_hash == found_hash {
+			true => Ok(encoded::Header::new(header.to_vec())),
+			false => Err(Error::WrongHash(expected_hash, found_hash)),
+		}
+	}
+}
+
+/// Request for a header by hash.
+pub struct HeaderByHash(pub H256);
+
+impl HeaderByHash {
+	/// Check a response for the header.
+	pub fn check_response(&self, header: &[u8]) -> Result<encoded::Header, Error> {
+		let hash = header.sha3();
+		match hash == self.0 {
+			true => Ok(encoded::Header::new(header.to_vec())),
+			false => Err(Error::WrongHash(self.0, hash)),
+		}
+	}
+}
+
+/// Request for a block, with header and precomputed hash.
+pub struct Body {
+	/// The block's header.
+	pub header: encoded::Header,
+	/// The block's hash.
+	pub hash: H256,
+}
+
+impl Body {
+	/// Check a response for this block body.
+	pub fn check_response(&self, body: &[u8]) -> Result<encoded::Block, Error> {
+		let body_view = UntrustedRlp::new(&body);
+
+		// check the integrity of the the body against the header
+		let tx_root = ::util::triehash::ordered_trie_root(body_view.at(0)?.iter().map(|r| r.as_raw().to_vec()));
+		if tx_root != self.header.transactions_root() {
+			return Err(Error::WrongTrieRoot(self.header.transactions_root(), tx_root));
+		}
+
+		let uncles_hash = body_view.at(1)?.as_raw().sha3();
+		if uncles_hash != self.header.uncles_hash() {
+			return Err(Error::WrongHash(self.header.uncles_hash(), uncles_hash);
+		}
+
+		// concatenate the header and the body.
+		let mut stream = RlpStream::new_list(3);
+		stream.append_raw(header.rlp().as_raw(), 1);
+		stream.append_raw(body, 2);
+
+		Ok(encoded::Block::new(stream.out()))
+	}
+}
+
+/// Request for a block's receipts with header for verification.
+pub struct BlockReceipts(pub encoded::Header);
+
+impl BlockReceipts {
+	/// Check a response with receipts against the stored header.
+	pub fn check_response(&self, receipts: &[Receipt]) -> Result<Vec<Receipt>, Error> {
+		let receipts_root = self.0.receipts_root();
+		let found_root = ::util::triehash::ordered_trie_root(receipts.iter().map(|r| ::rlp::encode(r).to_vec()));
+
+		match receipts_root == found_root {
+			true => Ok(receipts.to_vec()),
+			false => Err(Error::WrongTrieRoot(receipts_root, found_root)),
+		}
+	}
+}
+
+/// Request for an account structure.
+pub struct Account {
+	/// Header for verification.
+	pub header: encoded::Header,
+	/// Address requested.
+	pub address: Address,
+}
+
+impl Account {
+	/// Check a response with an account against the stored header.
+	pub fn check_response(&self, proof: &[Bytes]) -> Result<Vec<Receipt>, Error> {
+		let state_root = header.state_root();
+
+		let mut db = MemoryDB::new();
+		for node in proof { db.insert(&*node) }
+
+		match TrieDB::new(&db, &state_root).and_then(|t| t.get(&address.sha3()))? {
+
+		}
+	}
+}