Merge pull request #3755 from ethcore/lightserv

LES Part 3: Event handlers and handling responses

Cargo.lock

@@ -18,6 +18,7 @@ dependencies = [
  "ethcore-ipc-hypervisor 1.2.0",
  "ethcore-ipc-nano 1.5.0",
  "ethcore-ipc-tests 0.1.0",
+ "ethcore-light 1.5.0",
  "ethcore-logger 1.5.0",
  "ethcore-rpc 1.5.0",
  "ethcore-signer 1.5.0",
@@ -456,6 +457,21 @@ dependencies = [
  "semver 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "ethcore-light"
+version = "1.5.0"
+dependencies = [
+ "ethcore 1.5.0",
+ "ethcore-io 1.5.0",
+ "ethcore-ipc 1.5.0",
+ "ethcore-ipc-codegen 1.5.0",
+ "ethcore-network 1.5.0",
+ "ethcore-util 1.5.0",
+ "log 0.3.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rlp 0.1.0",
+ "time 0.1.35 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "ethcore-logger"
 version = "1.5.0"
@@ -665,6 +681,7 @@ dependencies = [
  "ethcore-ipc 1.5.0",
  "ethcore-ipc-codegen 1.5.0",
  "ethcore-ipc-nano 1.5.0",
+ "ethcore-light 1.5.0",
  "ethcore-network 1.5.0",
  "ethcore-util 1.5.0",
  "ethkey 0.2.0",

Cargo.toml

@@ -47,6 +47,7 @@ rlp = { path = "util/rlp" }
 ethcore-stratum = { path = "stratum" }
 ethcore-dapps = { path = "dapps", optional = true }
 clippy = { version = "0.0.103", optional = true}
+ethcore-light = { path = "ethcore/light" }
 
 [target.'cfg(windows)'.dependencies]
 winapi = "0.2"

ethcore/light/Cargo.toml

@@ -8,14 +8,18 @@ authors = ["Ethcore <admin@ethcore.io>"]
 build = "build.rs"
 
 [build-dependencies]
-"ethcore-ipc-codegen" = { path = "../../ipc/codegen" }
+"ethcore-ipc-codegen" = { path = "../../ipc/codegen", optional = true }
 
 [dependencies]
 log = "0.3"
-ethcore = { path = ".." }
+ethcore = { path = ".."}
 ethcore-util = { path = "../../util" }
 ethcore-network = { path = "../../util/network" }
 ethcore-io = { path = "../../util/io" }
-ethcore-ipc = { path = "../../ipc/rpc" }
+ethcore-ipc = { path = "../../ipc/rpc", optional = true }
 rlp = { path = "../../util/rlp" }
 time = "0.1"
+
+[features]
+default = []
+ipc = ["ethcore-ipc", "ethcore-ipc-codegen"]

ethcore/light/build.rs

@@ -14,8 +14,14 @@
 // You should have received a copy of the GNU General Public License
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.
 
+#[cfg(feature = "ipc")]
 extern crate ethcore_ipc_codegen;
 
+#[cfg(feature = "ipc")]
 fn main() {
 	ethcore_ipc_codegen::derive_binary("src/types/mod.rs.in").unwrap();
+	ethcore_ipc_codegen::derive_ipc_cond("src/provider.rs", true).unwrap();
 }
+
+#[cfg(not(feature = "ipc"))]
+fn main() { }

ethcore/light/src/lib.rs

@@ -33,8 +33,21 @@
 
 pub mod client;
 pub mod net;
+
+#[cfg(not(feature = "ipc"))]
 pub mod provider;
 
+#[cfg(feature = "ipc")]
+pub mod provider {
+    #![allow(dead_code, unused_assignments, unused_variables, missing_docs)] // codegen issues
+	include!(concat!(env!("OUT_DIR"), "/provider.rs"));
+}
+
+#[cfg(feature = "ipc")]
+pub mod remote {
+    pub use provider::LightProviderClient;
+}
+
 mod types;
 
 pub use self::provider::Provider;
@@ -47,6 +60,8 @@ extern crate ethcore;
 extern crate ethcore_util as util;
 extern crate ethcore_network as network;
 extern crate ethcore_io as io;
-extern crate ethcore_ipc as ipc;
 extern crate rlp;
 extern crate time;
+
+#[cfg(feature = "ipc")]
+extern crate ethcore_ipc as ipc;

ethcore/light/src/net/buffer_flow.rs

@@ -22,6 +22,9 @@
 //!
 //! This module provides an interface for configuration of buffer
 //! flow costs and recharge rates.
+//!
+//! Current default costs are picked completely arbitrarily, not based 
+//! on any empirical timings or mathematical models.
 
 use request;
 use super::packet;
@@ -273,6 +276,16 @@ impl FlowParams {
 	}
 }
 
+impl Default for FlowParams {
+	fn default() -> Self {
+		FlowParams {
+			limit: 50_000_000.into(),
+			costs: CostTable::default(),
+			recharge: 100_000.into(),
+		}
+	}
+}
+
 #[cfg(test)]
 mod tests {
 	use super::*;

ethcore/light/src/net/context.rs

@@ -0,0 +1,120 @@
+// 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/>.
+
+//! I/O and event context generalizations.
+
+use network::{NetworkContext, PeerId};
+
+use super::{Announcement, LightProtocol, ReqId};
+use super::error::Error;
+use request::Request;
+
+/// An I/O context which allows sending and receiving packets as well as 
+/// disconnecting peers. This is used as a generalization of the portions
+/// of a p2p network which the light protocol structure makes use of.
+pub trait IoContext {
+    /// Send a packet to a specific peer.
+    fn send(&self, peer: PeerId, packet_id: u8, packet_body: Vec<u8>);
+
+    /// Respond to a peer's message. Only works if this context is a byproduct
+    /// of a packet handler.
+    fn respond(&self, packet_id: u8, packet_body: Vec<u8>);
+
+    /// Disconnect a peer.
+    fn disconnect_peer(&self, peer: PeerId);
+
+    /// Disable a peer -- this is a disconnect + a time-out.
+    fn disable_peer(&self, peer: PeerId);
+
+    /// Get a peer's protocol version.
+    fn protocol_version(&self, peer: PeerId) -> Option<u8>;
+}
+
+impl<'a> IoContext for NetworkContext<'a> {
+    fn send(&self, peer: PeerId, packet_id: u8, packet_body: Vec<u8>) {
+        if let Err(e) = self.send(peer, packet_id, packet_body) {
+            debug!(target: "les", "Error sending packet to peer {}: {}", peer, e);
+        }
+    }
+
+    fn respond(&self, packet_id: u8, packet_body: Vec<u8>) {
+        if let Err(e) = self.respond(packet_id, packet_body) {
+            debug!(target: "les", "Error responding to peer message: {}", e);
+        }
+    }
+
+    fn disconnect_peer(&self, peer: PeerId) {
+        NetworkContext::disconnect_peer(self, peer);
+    }
+
+    fn disable_peer(&self, peer: PeerId) {
+        NetworkContext::disable_peer(self, peer);
+    }
+
+    fn protocol_version(&self, peer: PeerId) -> Option<u8> {
+        self.protocol_version(self.subprotocol_name(), peer)
+    }
+}
+
+/// Context for a protocol event.
+pub trait EventContext {
+    /// Get the peer relevant to the event e.g. message sender,
+    /// disconnected/connected peer.
+    fn peer(&self) -> PeerId;
+
+    /// Make a request from a peer.
+    fn request_from(&self, peer: PeerId, request: Request) -> Result<ReqId, Error>;
+
+    /// Make an announcement of new capabilities to the rest of the peers.
+    // TODO: maybe just put this on a timer in LightProtocol?
+    fn make_announcement(&self, announcement: Announcement);
+
+    /// Disconnect a peer.
+    fn disconnect_peer(&self, peer: PeerId);
+
+    /// Disable a peer.
+    fn disable_peer(&self, peer: PeerId);
+}
+
+/// Concrete implementation of `EventContext` over the light protocol struct and 
+/// an io context.
+pub struct Ctx<'a> {
+    /// Io context to enable immediate response to events.
+    pub io: &'a IoContext,
+    /// Protocol implementation.
+    pub proto: &'a LightProtocol,
+    /// Relevant peer for event.
+    pub peer: PeerId, 
+}
+
+impl<'a> EventContext for Ctx<'a> {
+    fn peer(&self) -> PeerId { self.peer }
+    fn request_from(&self, peer: PeerId, request: Request) -> Result<ReqId, Error> {
+        self.proto.request_from(self.io, &peer, request)
+    }
+
+    fn make_announcement(&self, announcement: Announcement) {
+        self.proto.make_announcement(self.io, announcement);
+    }
+
+    fn disconnect_peer(&self, peer: PeerId) {
+        self.io.disconnect_peer(peer);
+    }
+
+    fn disable_peer(&self, peer: PeerId) {
+        self.io.disable_peer(peer);
+    }
+}

ethcore/light/src/net/error.rs

@@ -54,6 +54,14 @@ pub enum Error {
 	WrongNetwork,
 	/// Unknown peer.
 	UnknownPeer,
+	/// Unsolicited response.
+	UnsolicitedResponse,
+	/// Not a server.
+	NotServer,
+	/// Unsupported protocol version.
+	UnsupportedProtocolVersion(u8),
+	/// Bad protocol version.
+	BadProtocolVersion,
 }
 
 impl Error {
@@ -67,6 +75,10 @@ impl Error {
 			Error::UnexpectedHandshake => Punishment::Disconnect,
 			Error::WrongNetwork => Punishment::Disable,
 			Error::UnknownPeer => Punishment::Disconnect,
+			Error::UnsolicitedResponse => Punishment::Disable,
+			Error::NotServer => Punishment::Disable,
+			Error::UnsupportedProtocolVersion(_) => Punishment::Disable,
+			Error::BadProtocolVersion => Punishment::Disable,
 		}
 	}
 }
@@ -92,7 +104,11 @@ impl fmt::Display for Error {
 			Error::UnrecognizedPacket(code) => write!(f, "Unrecognized packet: 0x{:x}", code),
 			Error::UnexpectedHandshake => write!(f, "Unexpected handshake"),
 			Error::WrongNetwork => write!(f, "Wrong network"),
-			Error::UnknownPeer => write!(f, "unknown peer"),
+			Error::UnknownPeer => write!(f, "Unknown peer"),
+			Error::UnsolicitedResponse => write!(f, "Peer provided unsolicited data"),
+			Error::NotServer => write!(f, "Peer not a server."),
+			Error::UnsupportedProtocolVersion(pv) => write!(f, "Unsupported protocol version: {}", pv),	
+			Error::BadProtocolVersion => write!(f, "Bad protocol version in handshake"),
 		}
 	}
 }

ethcore/light/src/net/mod.rs

@@ -20,36 +20,51 @@
 //! See https://github.com/ethcore/parity/wiki/Light-Ethereum-Subprotocol-(LES)
 
 use ethcore::transaction::SignedTransaction;
+use ethcore::receipt::Receipt;
+
 use io::TimerToken;
-use network::{NetworkProtocolHandler, NetworkContext, NetworkError, PeerId};
+use network::{NetworkProtocolHandler, NetworkContext, PeerId};
 use rlp::{RlpStream, Stream, UntrustedRlp, View};
 use util::hash::H256;
-use util::{Mutex, RwLock, U256};
-use time::SteadyTime;
+use util::{Bytes, Mutex, RwLock, U256};
+use time::{Duration, SteadyTime};
 
-use std::collections::{HashMap, HashSet};
+use std::collections::HashMap;
+use std::sync::Arc;
 use std::sync::atomic::{AtomicUsize, Ordering};
 
 use provider::Provider;
 use request::{self, Request};
 
 use self::buffer_flow::{Buffer, FlowParams};
+use self::context::Ctx;
 use self::error::{Error, Punishment};
 
 mod buffer_flow;
+mod context;
 mod error;
 mod status;
 
-pub use self::status::{Status, Capabilities, Announcement, NetworkId};
+#[cfg(test)]
+mod tests;
+
+pub use self::context::{EventContext, IoContext};
+pub use self::status::{Status, Capabilities, Announcement};
 
 const TIMEOUT: TimerToken = 0;
 const TIMEOUT_INTERVAL_MS: u64 = 1000;
 
-// LPV1
-const PROTOCOL_VERSION: u32 = 1;
+// minimum interval between updates.
+const UPDATE_INTERVAL_MS: i64 = 5000;
 
-// TODO [rob] make configurable.
-const PROTOCOL_ID: [u8; 3] = *b"les";
+// Supported protocol versions.
+pub const PROTOCOL_VERSIONS: &'static [u8] = &[1];
+
+// Max protocol version.
+pub const MAX_PROTOCOL_VERSION: u8 = 1;
+
+// Packet count for LES.
+pub const PACKET_COUNT: u8 = 15;
 
 // packet ID definitions.
 mod packet {
@@ -95,17 +110,19 @@ pub struct ReqId(usize);
 // may not have received one for.
 struct PendingPeer {
 	sent_head: H256,
+	last_update: SteadyTime,
+	proto_version: u8,
 }
 
 // data about each peer.
 struct Peer {
 	local_buffer: Buffer, // their buffer relative to us
-	remote_buffer: Buffer, // our buffer relative to them
-	current_asking: HashSet<usize>, // pending request ids.
 	status: Status,
 	capabilities: Capabilities,
-	remote_flow: FlowParams,
+	remote_flow: Option<(Buffer, FlowParams)>,
 	sent_head: H256, // last head we've given them.
+	last_update: SteadyTime,
+	proto_version: u8,
 }
 
 impl Peer {
@@ -126,38 +143,56 @@ impl Peer {
 
 		self.local_buffer.current()
 	}
-
-	// recharge remote buffer with remote flow params.
-	fn recharge_remote(&mut self) {
-		let flow = &mut self.remote_flow;
-		flow.recharge(&mut self.remote_buffer);
-	}
 }
 
 /// An LES event handler.
+///
+/// Each handler function takes a context which describes the relevant peer 
+/// and gives references to the IO layer and protocol structure so new messages
+/// can be dispatched immediately.
+///
+/// Request responses are not guaranteed to be complete or valid, but passed IDs will be correct.
+/// Response handlers are not given a copy of the original request; it is assumed
+/// that relevant data will be stored by interested handlers.
 pub trait Handler: Send + Sync {
 	/// Called when a peer connects.
-	fn on_connect(&self, _id: PeerId, _status: &Status, _capabilities: &Capabilities) { }
-	/// Called when a peer disconnects
-	fn on_disconnect(&self, _id: PeerId) { }
+	fn on_connect(&self, _ctx: &EventContext, _status: &Status, _capabilities: &Capabilities) { }
+	/// Called when a peer disconnects, with a list of unfulfilled request IDs as
+	/// of yet.
+	fn on_disconnect(&self, _ctx: &EventContext, _unfulfilled: &[ReqId]) { }
 	/// Called when a peer makes an announcement.
-	fn on_announcement(&self, _id: PeerId, _announcement: &Announcement) { }
+	fn on_announcement(&self, _ctx: &EventContext, _announcement: &Announcement) { }
 	/// Called when a peer requests relay of some transactions.
-	fn on_transactions(&self, _id: PeerId, _relay: &[SignedTransaction]) { }
+	fn on_transactions(&self, _ctx: &EventContext, _relay: &[SignedTransaction]) { }
+	/// Called when a peer responds with block bodies.
+	fn on_block_bodies(&self, _ctx: &EventContext, _req_id: ReqId, _bodies: &[Bytes]) { }
+	/// Called when a peer responds with block headers.
+	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
+	/// 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 
+	/// 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 on abort.
+	fn on_abort(&self) { }
 }
 
-// a request and the time it was made.
+// a request, the peer who it was made to, and the time it was made.
 struct Requested {
 	request: Request,
 	timestamp: SteadyTime,
+	peer_id: PeerId,
 }
 
 /// Protocol parameters.
 pub struct Params {
-	/// Genesis hash.
-	pub genesis_hash: H256,
 	/// Network id.
-	pub network_id: NetworkId,
+	pub network_id: u64,
 	/// Buffer flow parameters.
 	pub flow_params: FlowParams,
 	/// Initial capabilities.
@@ -175,9 +210,9 @@ pub struct Params {
 //   Locks must be acquired in the order declared, and when holding a read lock 
 //   on the peers, only one peer may be held at a time.
 pub struct LightProtocol {
-	provider: Box<Provider>,
+	provider: Arc<Provider>,
 	genesis_hash: H256,
-	network_id: NetworkId,
+	network_id: u64,
 	pending_peers: RwLock<HashMap<PeerId, PendingPeer>>,
 	peers: RwLock<HashMap<PeerId, Mutex<Peer>>>,
 	pending_requests: RwLock<HashMap<usize, Requested>>,
@@ -189,10 +224,13 @@ pub struct LightProtocol {
 
 impl LightProtocol {
 	/// Create a new instance of the protocol manager.
-	pub fn new(provider: Box<Provider>, params: Params) -> Self {
+	pub fn new(provider: Arc<Provider>, params: Params) -> Self {
+		debug!(target: "les", "Initializing LES handler");
+
+		let genesis_hash = provider.chain_info().genesis_hash;
 		LightProtocol {
 			provider: provider,
-			genesis_hash: params.genesis_hash,
+			genesis_hash: genesis_hash,
 			network_id: params.network_id,
 			pending_peers: RwLock::new(HashMap::new()),
 			peers: RwLock::new(HashMap::new()),
@@ -207,28 +245,37 @@ impl LightProtocol {
 	/// Check the maximum amount of requests of a specific type 
 	/// which a peer would be able to serve.
 	pub fn max_requests(&self, peer: PeerId, kind: request::Kind) -> Option<usize> {
-		self.peers.read().get(&peer).map(|peer| {
+		self.peers.read().get(&peer).and_then(|peer| {
 			let mut peer = peer.lock();
-			peer.recharge_remote();
-			peer.remote_flow.max_amount(&peer.remote_buffer, kind)
+			match peer.remote_flow.as_mut() {
+				Some(&mut (ref mut buf, ref flow)) => {
+					flow.recharge(buf);
+					Some(flow.max_amount(&*buf, kind))
+				}
+				None => None,
+			}
 		})
 	}
 
 	/// Make a request to a peer. 
 	///
-	/// Fails on: nonexistent peer, network error,
+	/// Fails on: nonexistent peer, network error, peer not server,
 	/// insufficient buffer. Does not check capabilities before sending.
 	/// On success, returns a request id which can later be coordinated 
 	/// with an event.
-	pub fn request_from(&self, io: &NetworkContext, peer_id: &PeerId, request: Request) -> Result<ReqId, Error> {
+	pub fn request_from(&self, io: &IoContext, peer_id: &PeerId, request: Request) -> Result<ReqId, Error> {
 		let peers = self.peers.read();
 		let peer = try!(peers.get(peer_id).ok_or_else(|| Error::UnknownPeer));
 		let mut peer = peer.lock();
 
-		peer.recharge_remote();
-
-		let max = peer.remote_flow.compute_cost(request.kind(), request.amount());
-		try!(peer.remote_buffer.deduct_cost(max));
+		match peer.remote_flow.as_mut() {
+			Some(&mut (ref mut buf, ref flow)) => {
+				flow.recharge(buf);
+				let max = flow.compute_cost(request.kind(), request.amount());
+				try!(buf.deduct_cost(max));
+			}
+			None => return Err(Error::NotServer),
+		}
 
 		let req_id = self.req_id.fetch_add(1, Ordering::SeqCst);
 		let packet_data = encode_request(&request, req_id);
@@ -242,12 +289,12 @@ impl LightProtocol {
 			request::Kind::HeaderProofs => packet::GET_HEADER_PROOFS,
 		};
 
-		try!(io.send(*peer_id, packet_id, packet_data));
+		io.send(*peer_id, packet_id, packet_data);
 
-		peer.current_asking.insert(req_id);
 		self.pending_requests.write().insert(req_id, Requested {
 			request: request,
 			timestamp: SteadyTime::now(),
+			peer_id: *peer_id,
 		});
 
 		Ok(ReqId(req_id))
@@ -255,8 +302,9 @@ impl LightProtocol {
 
 	/// Make an announcement of new chain head and capabilities to all peers.
 	/// The announcement is expected to be valid.
-	pub fn make_announcement(&self, io: &NetworkContext, mut announcement: Announcement) {
+	pub fn make_announcement(&self, io: &IoContext, mut announcement: Announcement) {
 		let mut reorgs_map = HashMap::new();
+		let now = SteadyTime::now();
 
 		// update stored capabilities
 		self.capabilities.write().update_from(&announcement);
@@ -264,6 +312,17 @@ impl LightProtocol {
 		// calculate reorg info and send packets
 		for (peer_id, peer_info) in self.peers.read().iter() {
 			let mut peer_info = peer_info.lock();
+
+			// TODO: "urgent" announcements like new blocks?
+			// the timer approach will skip 1 (possibly 2) in rare occasions.
+			if peer_info.sent_head == announcement.head_hash || 
+				peer_info.status.head_num >= announcement.head_num  ||
+				now - peer_info.last_update < Duration::milliseconds(UPDATE_INTERVAL_MS) {
+				continue 
+			}
+
+			peer_info.last_update = now;
+
 			let reorg_depth = reorgs_map.entry(peer_info.sent_head)
 				.or_insert_with(|| {
 					match self.provider.reorg_depth(&announcement.head_hash, &peer_info.sent_head) {
@@ -281,26 +340,133 @@ impl LightProtocol {
 			peer_info.sent_head = announcement.head_hash;
 			announcement.reorg_depth = *reorg_depth;
 
-			if let Err(e) = io.send(*peer_id, packet::ANNOUNCE, status::write_announcement(&announcement)) {
-				debug!(target: "les", "Error sending to peer {}: {}", peer_id, e);
-			}
+			io.send(*peer_id, packet::ANNOUNCE, status::write_announcement(&announcement));
 		}
 	}
 
 	/// Add an event handler.
 	/// Ownership will be transferred to the protocol structure,
 	/// and the handler will be kept alive as long as it is.
-	/// These are intended to be added at the beginning of the 
+	/// These are intended to be added when the protocol structure 
+	/// is initialized as a means of customizing its behavior.
 	pub fn add_handler(&mut self, handler: Box<Handler>) {
 		self.handlers.push(handler);
 	}
+
+	/// Signal to handlers that network activity is being aborted
+	/// and clear peer data.
+	pub fn abort(&self) {
+		for handler in &self.handlers {
+			handler.on_abort();
+		}
+
+		// acquire in order and hold.
+		let mut pending_peers = self.pending_peers.write();
+		let mut peers = self.peers.write();
+		let mut pending_requests = self.pending_requests.write();
+
+		pending_peers.clear();
+		peers.clear();
+		pending_requests.clear();
+	}
+
+	// Does the common pre-verification of responses before the response itself 
+	// is actually decoded:
+	//   - check whether peer exists
+	//   - check whether request was made
+	//   - check whether request kinds match
+	fn pre_verify_response(&self, peer: &PeerId, kind: request::Kind, raw: &UntrustedRlp) -> Result<ReqId, Error> {
+		let req_id: usize = try!(raw.val_at(0));
+		let cur_buffer: U256 = try!(raw.val_at(1));
+
+		trace!(target: "les", "pre-verifying response from peer {}, kind={:?}", peer, kind);
+
+		match self.pending_requests.write().remove(&req_id) {
+			None => return Err(Error::UnsolicitedResponse),
+			Some(requested) => {
+				if requested.peer_id != *peer || requested.request.kind() != kind {
+					return Err(Error::UnsolicitedResponse)
+				}
+			}
+		}
+
+		let peers = self.peers.read();
+		match peers.get(peer) {
+			Some(peer_info) => {
+				let mut peer_info = peer_info.lock();
+				match peer_info.remote_flow.as_mut() {
+					Some(&mut (ref mut buf, ref mut flow)) => {
+						let actual_buffer = ::std::cmp::min(cur_buffer, *flow.limit());				
+						buf.update_to(actual_buffer)
+					}
+					None => return Err(Error::NotServer), // this really should be impossible.
+				}
+				Ok(ReqId(req_id))
+			}
+			None => Err(Error::UnknownPeer), // probably only occurs in a race of some kind.
+		}
+	}
+
+	// handle a packet using the given io context.
+	fn handle_packet(&self, io: &IoContext, peer: &PeerId, packet_id: u8, data: &[u8]) {
+		let rlp = UntrustedRlp::new(data);
+
+		trace!(target: "les", "Incoming packet {} from peer {}", packet_id, peer);
+
+		// handle the packet
+		let res = match packet_id {
+			packet::STATUS => self.status(peer, io, rlp),
+			packet::ANNOUNCE => self.announcement(peer, io, rlp),
+
+			packet::GET_BLOCK_HEADERS => self.get_block_headers(peer, io, rlp),
+			packet::BLOCK_HEADERS => self.block_headers(peer, io, rlp),
+
+			packet::GET_BLOCK_BODIES => self.get_block_bodies(peer, io, rlp),
+			packet::BLOCK_BODIES => self.block_bodies(peer, io, rlp),
+
+			packet::GET_RECEIPTS => self.get_receipts(peer, io, rlp),
+			packet::RECEIPTS => self.receipts(peer, io, rlp),
+
+			packet::GET_PROOFS => self.get_proofs(peer, io, rlp),
+			packet::PROOFS => self.proofs(peer, io, rlp),
+
+			packet::GET_CONTRACT_CODES => self.get_contract_code(peer, io, rlp),
+			packet::CONTRACT_CODES => self.contract_code(peer, io, rlp),
+
+			packet::GET_HEADER_PROOFS => self.get_header_proofs(peer, io, rlp),
+			packet::HEADER_PROOFS => self.header_proofs(peer, io, rlp),
+
+			packet::SEND_TRANSACTIONS => self.relay_transactions(peer, io, rlp),
+
+			other => {
+				Err(Error::UnrecognizedPacket(other))
+			}
+		};
+
+		// if something went wrong, figure out how much to punish the peer.
+		if let Err(e) = res {
+			match e.punishment() {
+				Punishment::None => {}
+				Punishment::Disconnect => {
+					debug!(target: "les", "Disconnecting peer {}: {}", peer, e);
+					io.disconnect_peer(*peer)
+				}
+				Punishment::Disable => {
+					debug!(target: "les", "Disabling peer {}: {}", peer, e);
+					io.disable_peer(*peer)
+				}
+			}
+		}
+	}
 }
 
 impl LightProtocol {
 	// called when a peer connects.
-	fn on_connect(&self, peer: &PeerId, io: &NetworkContext) {
+	fn on_connect(&self, peer: &PeerId, io: &IoContext) {
 		let peer = *peer;
 
+		trace!(target: "les", "Peer {} connecting", peer);
+
 		match self.send_status(peer, io) {
 			Ok(pending_peer) => {
 				self.pending_peers.write().insert(peer, pending_peer);
@@ -313,44 +479,69 @@ impl LightProtocol {
 	}
 
 	// called when a peer disconnects.
-	fn on_disconnect(&self, peer: PeerId) {
-		// TODO: reassign all requests assigned to this peer.
+	fn on_disconnect(&self, peer: PeerId, io: &IoContext) {
+		trace!(target: "les", "Peer {} disconnecting", peer);
+
+
 		self.pending_peers.write().remove(&peer);
 		if self.peers.write().remove(&peer).is_some() {
+			let unfulfilled: Vec<_> = self.pending_requests.read()
+				.iter()
+				.filter(|&(_, r)| r.peer_id == peer)
+				.map(|(&id, _)| ReqId(id))
+				.collect();
+
+			{
+				let mut pending = self.pending_requests.write();
+				for &ReqId(ref inner) in &unfulfilled {
+					pending.remove(inner);
+				}
+			}
+
 			for handler in &self.handlers {
-				handler.on_disconnect(peer)
+				handler.on_disconnect(&Ctx {
+					peer: peer,
+					io: io,
+					proto: self,
+				}, &unfulfilled)
 			}	
 		}
 	}
 
 	// send status to a peer.
-	fn send_status(&self, peer: PeerId, io: &NetworkContext) -> Result<PendingPeer, NetworkError> {
-		let chain_info = self.provider.chain_info();
+	fn send_status(&self, peer: PeerId, io: &IoContext) -> Result<PendingPeer, Error> {
+		let proto_version = try!(io.protocol_version(peer).ok_or(Error::WrongNetwork));
 
-		// TODO: could update capabilities here.
+		if PROTOCOL_VERSIONS.iter().find(|x| **x == proto_version).is_none() {
+			return Err(Error::UnsupportedProtocolVersion(proto_version));
+		}
+		
+		let chain_info = self.provider.chain_info();
 
 		let status = Status {
 			head_td: chain_info.total_difficulty,
 			head_hash: chain_info.best_block_hash,
 			head_num: chain_info.best_block_number,
 			genesis_hash: chain_info.genesis_hash,
-			protocol_version: PROTOCOL_VERSION,
+			protocol_version: proto_version as u32, // match peer proto version
 			network_id: self.network_id,
 			last_head: None,
 		};
 
 		let capabilities = self.capabilities.read().clone();
-		let status_packet = status::write_handshake(&status, &capabilities, &self.flow_params);
+		let status_packet = status::write_handshake(&status, &capabilities, Some(&self.flow_params));
 
-		try!(io.send(peer, packet::STATUS, status_packet));
+		io.send(peer, packet::STATUS, status_packet);
 
 		Ok(PendingPeer {
 			sent_head: chain_info.best_block_hash,
+			last_update: SteadyTime::now(),
+			proto_version: proto_version,			
 		})
 	}
 
 	// Handle status message from peer.
-	fn status(&self, peer: &PeerId, data: UntrustedRlp) -> Result<(), Error> {
+	fn status(&self, peer: &PeerId, io: &IoContext, data: UntrustedRlp) -> Result<(), Error> {
 		let pending = match self.pending_peers.write().remove(peer) {
 			Some(pending) => pending,
 			None => {
@@ -366,63 +557,80 @@ impl LightProtocol {
 			return Err(Error::WrongNetwork);
 		}
 
+		if Some(status.protocol_version as u8) != io.protocol_version(*peer) {
+			return Err(Error::BadProtocolVersion);
+		}
+
+		let remote_flow = flow_params.map(|params| (params.create_buffer(), params));
+
 		self.peers.write().insert(*peer, Mutex::new(Peer {
 			local_buffer: self.flow_params.create_buffer(),
-			remote_buffer: flow_params.create_buffer(),
-			current_asking: HashSet::new(),
 			status: status.clone(),
 			capabilities: capabilities.clone(),
-			remote_flow: flow_params,
+			remote_flow: remote_flow,
 			sent_head: pending.sent_head,
+			last_update: pending.last_update,
+			proto_version: pending.proto_version,
 		}));
 
 		for handler in &self.handlers {
-			handler.on_connect(*peer, &status, &capabilities)
+			handler.on_connect(&Ctx {
+				peer: *peer,
+				io: io,	
+				proto: self,
+			}, &status, &capabilities)
 		}
 
 		Ok(())
 	}
 
 	// Handle an announcement.
-	fn announcement(&self, peer: &PeerId, data: UntrustedRlp) -> Result<(), Error> {
+	fn announcement(&self, peer: &PeerId, io: &IoContext, data: UntrustedRlp) -> Result<(), Error> {
 		if !self.peers.read().contains_key(peer) {
 			debug!(target: "les", "Ignoring announcement from unknown peer");
 			return Ok(())
 		}
 
 		let announcement = try!(status::parse_announcement(data));
-		let peers = self.peers.read();
 
-		let peer_info = match peers.get(peer) {
-			Some(info) => info,
-			None => return Ok(()),
-		};
-
-		let mut peer_info = peer_info.lock();
-
-		// update status.
+		// scope to ensure locks are dropped before moving into handler-space.
 		{
-			// TODO: punish peer if they've moved backwards.
-			let status = &mut peer_info.status;
-			let last_head = status.head_hash;
-			status.head_hash = announcement.head_hash;
-			status.head_td = announcement.head_td;
-			status.head_num = announcement.head_num;
-			status.last_head = Some((last_head, announcement.reorg_depth));
+			let peers = self.peers.read();
+			let peer_info = match peers.get(peer) {
+				Some(info) => info,
+				None => return Ok(()),
+			};
+
+			let mut peer_info = peer_info.lock();
+
+			// update status.
+			{
+				// TODO: punish peer if they've moved backwards.
+				let status = &mut peer_info.status;
+				let last_head = status.head_hash;
+				status.head_hash = announcement.head_hash;
+				status.head_td = announcement.head_td;
+				status.head_num = announcement.head_num;
+				status.last_head = Some((last_head, announcement.reorg_depth));
+			}
+
+			// update capabilities.
+			peer_info.capabilities.update_from(&announcement);
 		}
 
-		// update capabilities.
-		peer_info.capabilities.update_from(&announcement);
-
 		for handler in &self.handlers {
-			handler.on_announcement(*peer, &announcement);
+			handler.on_announcement(&Ctx {
+				peer: *peer,
+				io: io,
+				proto: self,
+			}, &announcement);
 		}
 
 		Ok(())
 	}
 
 	// Handle a request for block headers.
-	fn get_block_headers(&self, peer: &PeerId, io: &NetworkContext, data: UntrustedRlp) -> Result<(), Error> {
+	fn get_block_headers(&self, peer: &PeerId, io: &IoContext, data: UntrustedRlp) -> Result<(), Error> {
 		const MAX_HEADERS: usize = 512;
 
 		let peers = self.peers.read();
@@ -467,16 +675,29 @@ impl LightProtocol {
 			}
 
 			stream.out()
-		}).map_err(Into::into)
+		});
+
+		Ok(())
 	}
 
 	// Receive a response for block headers.
-	fn block_headers(&self, _: &PeerId, _: &NetworkContext, _: UntrustedRlp) -> Result<(), Error> {
-		unimplemented!()
+	fn block_headers(&self, peer: &PeerId, io: &IoContext, raw: UntrustedRlp) -> Result<(), Error> {
+		let req_id = try!(self.pre_verify_response(peer, request::Kind::Headers, &raw));
+		let raw_headers: Vec<_> = raw.iter().skip(2).map(|x| x.as_raw().to_owned()).collect();
+
+		for handler in &self.handlers {
+			handler.on_block_headers(&Ctx {
+				peer: *peer,
+				io: io,
+				proto: self,
+			}, req_id, &raw_headers);
+		}
+
+		Ok(())
 	}
 
 	// Handle a request for block bodies.
-	fn get_block_bodies(&self, peer: &PeerId, io: &NetworkContext, data: UntrustedRlp) -> Result<(), Error> {
+	fn get_block_bodies(&self, peer: &PeerId, io: &IoContext, data: UntrustedRlp) -> Result<(), Error> {
 		const MAX_BODIES: usize = 256;
 
 		let peers = self.peers.read();
@@ -513,16 +734,29 @@ impl LightProtocol {
 			}
 
 			stream.out()
-		}).map_err(Into::into)
+		});
+
+		Ok(())
 	}
 
 	// Receive a response for block bodies.
-	fn block_bodies(&self, _: &PeerId, _: &NetworkContext, _: UntrustedRlp) -> Result<(), Error> {
-		unimplemented!()
+	fn block_bodies(&self, peer: &PeerId, io: &IoContext, raw: UntrustedRlp) -> Result<(), Error> {
+		let req_id = try!(self.pre_verify_response(peer, request::Kind::Bodies, &raw));
+		let raw_bodies: Vec<Bytes> = raw.iter().skip(2).map(|x| x.as_raw().to_owned()).collect();
+
+		for handler in &self.handlers {
+			handler.on_block_bodies(&Ctx {
+				peer: *peer,
+				io: io,
+				proto: self,
+			}, req_id, &raw_bodies);
+		}
+
+		Ok(())
 	}
 
 	// Handle a request for receipts.
-	fn get_receipts(&self, peer: &PeerId, io: &NetworkContext, data: UntrustedRlp) -> Result<(), Error> {
+	fn get_receipts(&self, peer: &PeerId, io: &IoContext, data: UntrustedRlp) -> Result<(), Error> {
 		const MAX_RECEIPTS: usize = 256;
 
 		let peers = self.peers.read();
@@ -559,16 +793,33 @@ impl LightProtocol {
 			}
 
 			stream.out()
-		}).map_err(Into::into)
+		});
+
+		Ok(())
 	}
 
 	// Receive a response for receipts.
-	fn receipts(&self, _: &PeerId, _: &NetworkContext, _: UntrustedRlp) -> Result<(), Error> {
-		unimplemented!()
+	fn receipts(&self, peer: &PeerId, io: &IoContext, raw: UntrustedRlp) -> Result<(), Error> {
+		let req_id = try!(self.pre_verify_response(peer, request::Kind::Receipts, &raw));
+		let raw_receipts: Vec<Vec<Receipt>> = try!(raw
+			.iter()
+			.skip(2)
+			.map(|x| x.as_val())
+			.collect());
+
+		for handler in &self.handlers {
+			handler.on_receipts(&Ctx {
+				peer: *peer,
+				io: io,
+				proto: self,
+			}, req_id, &raw_receipts);
+		}
+
+		Ok(())
 	}
 
 	// Handle a request for proofs.
-	fn get_proofs(&self, peer: &PeerId, io: &NetworkContext, data: UntrustedRlp) -> Result<(), Error> {
+	fn get_proofs(&self, peer: &PeerId, io: &IoContext, data: UntrustedRlp) -> Result<(), Error> {
 		const MAX_PROOFS: usize = 128;
 
 		let peers = self.peers.read();
@@ -616,16 +867,33 @@ impl LightProtocol {
 			}
 
 			stream.out()
-		}).map_err(Into::into)
+		});
+
+		Ok(())
 	}
 
 	// Receive a response for proofs.
-	fn proofs(&self, _: &PeerId, _: &NetworkContext, _: UntrustedRlp) -> Result<(), Error> {
-		unimplemented!()
+	fn proofs(&self, peer: &PeerId, io: &IoContext, raw: UntrustedRlp) -> Result<(), Error> {
+		let req_id = try!(self.pre_verify_response(peer, request::Kind::StateProofs, &raw));
+
+		let raw_proofs: Vec<Vec<Bytes>> = raw.iter()
+			.skip(2)
+			.map(|x| x.iter().map(|node| node.as_raw().to_owned()).collect())
+			.collect();
+
+		for handler in &self.handlers { 
+			handler.on_state_proofs(&Ctx {
+				peer: *peer,
+				io: io,
+				proto: self,
+			}, req_id, &raw_proofs);
+		}
+
+		Ok(())
 	}
 
 	// Handle a request for contract code.
-	fn get_contract_code(&self, peer: &PeerId, io: &NetworkContext, data: UntrustedRlp) -> Result<(), Error> {
+	fn get_contract_code(&self, peer: &PeerId, io: &IoContext, data: UntrustedRlp) -> Result<(), Error> {
 		const MAX_CODES: usize = 256;
 
 		let peers = self.peers.read();
@@ -667,20 +935,34 @@ impl LightProtocol {
 			stream.append(&req_id).append(&cur_buffer);
 
 			for code in response {
-				stream.append_raw(&code, 1);
+				stream.append(&code);
 			}
 
 			stream.out()
-		}).map_err(Into::into)
+		});
+
+		Ok(())
 	}
 
 	// Receive a response for contract code.
-	fn contract_code(&self, _: &PeerId, _: &NetworkContext, _: UntrustedRlp) -> Result<(), Error> {
-		unimplemented!()
+	fn contract_code(&self, peer: &PeerId, io: &IoContext, raw: UntrustedRlp) -> Result<(), Error> {
+		let req_id = try!(self.pre_verify_response(peer, request::Kind::Codes, &raw));
+
+		let raw_code: Vec<Bytes> = try!(raw.iter().skip(2).map(|x| x.as_val()).collect());
+
+		for handler in &self.handlers { 
+			handler.on_code(&Ctx {
+				peer: *peer,
+				io: io,
+				proto: self,
+			}, req_id, &raw_code);
+		}
+
+		Ok(())
 	}
 
 	// Handle a request for header proofs
-	fn get_header_proofs(&self, peer: &PeerId, io: &NetworkContext, data: UntrustedRlp) -> Result<(), Error> {
+	fn get_header_proofs(&self, peer: &PeerId, io: &IoContext, data: UntrustedRlp) -> Result<(), Error> {
 		const MAX_PROOFS: usize = 256;
 
 		let peers = self.peers.read();
@@ -727,16 +1009,37 @@ impl LightProtocol {
 			}
 
 			stream.out()
-		}).map_err(Into::into)
+		});
+
+		Ok(())
 	}
 
 	// Receive a response for header proofs
-	fn header_proofs(&self, _: &PeerId, _: &NetworkContext, _: UntrustedRlp) -> Result<(), Error> {
-		unimplemented!()
+	fn header_proofs(&self, peer: &PeerId, io: &IoContext, raw: UntrustedRlp) -> Result<(), Error> {
+		fn decode_res(raw: UntrustedRlp) -> Result<(Bytes, Vec<Bytes>), ::rlp::DecoderError> {
+			Ok((
+				try!(raw.val_at(0)),
+				try!(raw.at(1)).iter().map(|x| x.as_raw().to_owned()).collect(),
+			))
+		}
+		
+		
+		let req_id = try!(self.pre_verify_response(peer, request::Kind::HeaderProofs, &raw));
+		let raw_proofs: Vec<_> = try!(raw.iter().skip(2).map(decode_res).collect());
+
+		for handler in &self.handlers { 
+			handler.on_header_proofs(&Ctx {
+				peer: *peer,
+				io: io,
+				proto: self,
+			}, req_id, &raw_proofs);
+		}
+
+		Ok(())
 	}
 
 	// Receive a set of transactions to relay.
-	fn relay_transactions(&self, peer: &PeerId, data: UntrustedRlp) -> Result<(), Error> {
+	fn relay_transactions(&self, peer: &PeerId, io: &IoContext, data: UntrustedRlp) -> Result<(), Error> {
 		const MAX_TRANSACTIONS: usize = 256;
 
 		let txs: Vec<_> = try!(data.iter().take(MAX_TRANSACTIONS).map(|x| x.as_val::<SignedTransaction>()).collect());
@@ -744,7 +1047,11 @@ impl LightProtocol {
 		debug!(target: "les", "Received {} transactions to relay from peer {}", txs.len(), peer);
 
 		for handler in &self.handlers {
-			handler.on_transactions(*peer, &txs);
+			handler.on_transactions(&Ctx {
+				peer: *peer,
+				io: io,
+				proto: self,	
+			}, &txs);
 		}
 
 		Ok(())
@@ -757,60 +1064,15 @@ impl NetworkProtocolHandler for LightProtocol {
 	}
 
 	fn read(&self, io: &NetworkContext, peer: &PeerId, packet_id: u8, data: &[u8]) {
-		let rlp = UntrustedRlp::new(data);
-
-		// handle the packet
-		let res = match packet_id {
-			packet::STATUS => self.status(peer, rlp),
-			packet::ANNOUNCE => self.announcement(peer, rlp),
-
-			packet::GET_BLOCK_HEADERS => self.get_block_headers(peer, io, rlp),
-			packet::BLOCK_HEADERS => self.block_headers(peer, io, rlp),
-
-			packet::GET_BLOCK_BODIES => self.get_block_bodies(peer, io, rlp),
-			packet::BLOCK_BODIES => self.block_bodies(peer, io, rlp),
-
-			packet::GET_RECEIPTS => self.get_receipts(peer, io, rlp),
-			packet::RECEIPTS => self.receipts(peer, io, rlp),
-
-			packet::GET_PROOFS => self.get_proofs(peer, io, rlp),
-			packet::PROOFS => self.proofs(peer, io, rlp),
-
-			packet::GET_CONTRACT_CODES => self.get_contract_code(peer, io, rlp),
-			packet::CONTRACT_CODES => self.contract_code(peer, io, rlp),
-
-			packet::GET_HEADER_PROOFS => self.get_header_proofs(peer, io, rlp),
-			packet::HEADER_PROOFS => self.header_proofs(peer, io, rlp),
-
-			packet::SEND_TRANSACTIONS => self.relay_transactions(peer, rlp),
-
-			other => {
-				Err(Error::UnrecognizedPacket(other))
-			}
-		};
-
-		// if something went wrong, figure out how much to punish the peer.
-		if let Err(e) = res {
-			match e.punishment() {
-				Punishment::None => {}
-				Punishment::Disconnect => {
-					debug!(target: "les", "Disconnecting peer {}: {}", peer, e);
-					io.disconnect_peer(*peer)
-				}
-				Punishment::Disable => {
-					debug!(target: "les", "Disabling peer {}: {}", peer, e);
-					io.disable_peer(*peer)
-				}
-			}
-		}
+		self.handle_packet(io, peer, packet_id, data);
 	}
 
 	fn connected(&self, io: &NetworkContext, peer: &PeerId) {
 		self.on_connect(peer, io);
 	}
 
-	fn disconnected(&self, _io: &NetworkContext, peer: &PeerId) {
-		self.on_disconnect(*peer);
+	fn disconnected(&self, io: &NetworkContext, peer: &PeerId) {
+		self.on_disconnect(*peer, io);
 	}
 
 	fn timeout(&self, _io: &NetworkContext, timer: TimerToken) {

ethcore/light/src/net/status.rs

@@ -82,26 +82,6 @@ impl Key {
 	}
 }
 
-/// Network ID structure.
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
-#[repr(u32)]
-pub enum NetworkId {
-	/// ID for the mainnet
-	Mainnet = 1,
-	/// ID for the testnet
-	Testnet = 0,
-}
-
-impl NetworkId {
-	fn from_raw(raw: u32) -> Option<Self> {
-		match raw {
-			0 => Some(NetworkId::Testnet),
-			1 => Some(NetworkId::Mainnet),
-			_ => None,
-		}
-	}
-}
-
 // helper for decoding key-value pairs in the handshake or an announcement.
 struct Parser<'a> {
 	pos: usize,
@@ -118,6 +98,7 @@ impl<'a> Parser<'a> {
 	// expect a specific next key, and get the value's RLP.
 	// if the key isn't found, the position isn't advanced.
 	fn expect_raw(&mut self, key: Key) -> Result<UntrustedRlp<'a>, DecoderError> {
+		trace!(target: "les", "Expecting key {}", key.as_str());
 		let pre_pos = self.pos;
 		if let Some((k, val)) = try!(self.get_next()) {
 			if k == key { return Ok(val) }
@@ -164,7 +145,7 @@ pub struct Status {
 	/// Protocol version.
 	pub protocol_version: u32,
 	/// Network id of this peer.
-	pub network_id: NetworkId,
+	pub network_id: u64,
 	/// Total difficulty of the head of the chain.
 	pub head_td: U256,
 	/// Hash of the best block.
@@ -217,7 +198,7 @@ impl Capabilities {
 ///   - chain status
 ///   - serving capabilities
 ///   - buffer flow parameters
-pub fn parse_handshake(rlp: UntrustedRlp) -> Result<(Status, Capabilities, FlowParams), DecoderError> {
+pub fn parse_handshake(rlp: UntrustedRlp) -> Result<(Status, Capabilities, Option<FlowParams>), DecoderError> {
 	let mut parser = Parser {
 		pos: 0,
 		rlp: rlp,
@@ -225,8 +206,7 @@ pub fn parse_handshake(rlp: UntrustedRlp) -> Result<(Status, Capabilities, FlowP
 
 	let status = Status {
 		protocol_version: try!(parser.expect(Key::ProtocolVersion)),
-		network_id: try!(parser.expect(Key::NetworkId)
-			.and_then(|id: u32| NetworkId::from_raw(id).ok_or(DecoderError::Custom("Invalid network ID")))),
+		network_id: try!(parser.expect(Key::NetworkId)),
 		head_td: try!(parser.expect(Key::HeadTD)),
 		head_hash: try!(parser.expect(Key::HeadHash)),
 		head_num: try!(parser.expect(Key::HeadNum)),
@@ -241,20 +221,23 @@ pub fn parse_handshake(rlp: UntrustedRlp) -> Result<(Status, Capabilities, FlowP
 		tx_relay: parser.expect_raw(Key::TxRelay).is_ok(),
 	};
 
-	let flow_params = FlowParams::new(
-		try!(parser.expect(Key::BufferLimit)),
-		try!(parser.expect(Key::BufferCostTable)),
-		try!(parser.expect(Key::BufferRechargeRate)),
-	);
+	let flow_params = match (
+		parser.expect(Key::BufferLimit),
+		parser.expect(Key::BufferCostTable),
+		parser.expect(Key::BufferRechargeRate)
+	) {
+		(Ok(bl), Ok(bct), Ok(brr)) => Some(FlowParams::new(bl, bct, brr)),
+		_ => None,
+	};
 
 	Ok((status, capabilities, flow_params))
 }
 
 /// Write a handshake, given status, capabilities, and flow parameters.
-pub fn write_handshake(status: &Status, capabilities: &Capabilities, flow_params: &FlowParams) -> Vec<u8> {
+pub fn write_handshake(status: &Status, capabilities: &Capabilities, flow_params: Option<&FlowParams>) -> Vec<u8> {
 	let mut pairs = Vec::new();
 	pairs.push(encode_pair(Key::ProtocolVersion, &status.protocol_version));
-	pairs.push(encode_pair(Key::NetworkId, &(status.network_id as u32)));
+	pairs.push(encode_pair(Key::NetworkId, &(status.network_id as u64)));
 	pairs.push(encode_pair(Key::HeadTD, &status.head_td));
 	pairs.push(encode_pair(Key::HeadHash, &status.head_hash));
 	pairs.push(encode_pair(Key::HeadNum, &status.head_num));
@@ -273,9 +256,11 @@ pub fn write_handshake(status: &Status, capabilities: &Capabilities, flow_params
 		pairs.push(encode_flag(Key::TxRelay));
 	}
 
-	pairs.push(encode_pair(Key::BufferLimit, flow_params.limit()));
-	pairs.push(encode_pair(Key::BufferCostTable, flow_params.cost_table()));
-	pairs.push(encode_pair(Key::BufferRechargeRate, flow_params.recharge_rate()));
+	if let Some(flow_params) = flow_params {
+		pairs.push(encode_pair(Key::BufferLimit, flow_params.limit()));
+		pairs.push(encode_pair(Key::BufferCostTable, flow_params.cost_table()));
+		pairs.push(encode_pair(Key::BufferRechargeRate, flow_params.recharge_rate()));
+	}
 
 	let mut stream = RlpStream::new_list(pairs.len());
 
@@ -385,7 +370,7 @@ mod tests {
 	fn full_handshake() {
 		let status = Status {
 			protocol_version: 1,
-			network_id: NetworkId::Mainnet,
+			network_id: 1,
 			head_td: U256::default(),
 			head_hash: H256::default(),
 			head_num: 10,
@@ -406,21 +391,21 @@ mod tests {
 			1000.into(),
 		);
 
-		let handshake = write_handshake(&status, &capabilities, &flow_params);
+		let handshake = write_handshake(&status, &capabilities, Some(&flow_params));
 
 		let (read_status, read_capabilities, read_flow)
 			= parse_handshake(UntrustedRlp::new(&handshake)).unwrap();
 
 		assert_eq!(read_status, status);
 		assert_eq!(read_capabilities, capabilities);
-		assert_eq!(read_flow, flow_params);
+		assert_eq!(read_flow.unwrap(), flow_params);
 	}
 
 	#[test]
 	fn partial_handshake() {
 		let status = Status {
 			protocol_version: 1,
-			network_id: NetworkId::Mainnet,
+			network_id: 1,
 			head_td: U256::default(),
 			head_hash: H256::default(),
 			head_num: 10,
@@ -441,21 +426,21 @@ mod tests {
 			1000.into(),
 		);
 
-		let handshake = write_handshake(&status, &capabilities, &flow_params);
+		let handshake = write_handshake(&status, &capabilities, Some(&flow_params));
 
 		let (read_status, read_capabilities, read_flow)
 			= parse_handshake(UntrustedRlp::new(&handshake)).unwrap();
 
 		assert_eq!(read_status, status);
 		assert_eq!(read_capabilities, capabilities);
-		assert_eq!(read_flow, flow_params);
+		assert_eq!(read_flow.unwrap(), flow_params);
 	}
 
 	#[test]
 	fn skip_unknown_keys() {
 		let status = Status {
 			protocol_version: 1,
-			network_id: NetworkId::Mainnet,
+			network_id: 1,
 			head_td: U256::default(),
 			head_hash: H256::default(),
 			head_num: 10,
@@ -476,7 +461,7 @@ mod tests {
 			1000.into(),
 		);
 
-		let handshake = write_handshake(&status, &capabilities, &flow_params);
+		let handshake = write_handshake(&status, &capabilities, Some(&flow_params));
 		let interleaved = {
 			let handshake = UntrustedRlp::new(&handshake);
 			let mut stream = RlpStream::new_list(handshake.item_count() * 3);
@@ -498,7 +483,7 @@ mod tests {
 
 		assert_eq!(read_status, status);
 		assert_eq!(read_capabilities, capabilities);
-		assert_eq!(read_flow, flow_params);
+		assert_eq!(read_flow.unwrap(), flow_params);
 	}
 
 	#[test]
@@ -548,4 +533,33 @@ mod tests {
 		let out = stream.drain();
 		assert!(parse_announcement(UntrustedRlp::new(&out)).is_ok());
 	}
+
+	#[test]
+	fn optional_flow() {
+		let status = Status {
+			protocol_version: 1,
+			network_id: 1,
+			head_td: U256::default(),
+			head_hash: H256::default(),
+			head_num: 10,
+			genesis_hash: H256::zero(),
+			last_head: None,
+		};
+
+		let capabilities = Capabilities {
+			serve_headers: true,
+			serve_chain_since: Some(5),
+			serve_state_since: Some(8),
+			tx_relay: true,
+		};
+
+		let handshake = write_handshake(&status, &capabilities, None);
+
+		let (read_status, read_capabilities, read_flow)
+			= parse_handshake(UntrustedRlp::new(&handshake)).unwrap();
+
+		assert_eq!(read_status, status);
+		assert_eq!(read_capabilities, capabilities);
+		assert!(read_flow.is_none());
+	}
 }

ethcore/light/src/net/tests/mod.rs

@@ -0,0 +1,512 @@
+// 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/>.
+
+//! Tests for the `LightProtocol` implementation.
+//! These don't test of the higher level logic on top of 
+
+use ethcore::blockchain_info::BlockChainInfo;
+use ethcore::client::{BlockChainClient, EachBlockWith, TestBlockChainClient};
+use ethcore::ids::BlockID;
+use ethcore::transaction::SignedTransaction;
+use network::PeerId;
+
+use net::buffer_flow::FlowParams;
+use net::context::IoContext;
+use net::status::{Capabilities, Status, write_handshake};
+use net::{encode_request, LightProtocol, Params, packet};
+use provider::Provider;
+use request::{self, Request, Headers};
+
+use rlp::*;
+use util::{Bytes, H256, U256};
+
+use std::sync::Arc;
+
+// expected result from a call.
+#[derive(Debug, PartialEq, Eq)]
+enum Expect {
+	/// Expect to have message sent to peer.
+	Send(PeerId, u8, Vec<u8>),
+	/// Expect this response.
+	Respond(u8, Vec<u8>),
+	/// Expect a punishment (disconnect/disable)
+	Punish(PeerId),
+	/// Expect nothing.
+	Nothing,
+}
+
+impl IoContext for Expect {
+	fn send(&self, peer: PeerId, packet_id: u8, packet_body: Vec<u8>) {
+		assert_eq!(self, &Expect::Send(peer, packet_id, packet_body));
+	}
+
+	fn respond(&self, packet_id: u8, packet_body: Vec<u8>) {
+		assert_eq!(self, &Expect::Respond(packet_id, packet_body));
+	}
+
+	fn disconnect_peer(&self, peer: PeerId) {
+		assert_eq!(self, &Expect::Punish(peer));
+	}
+
+	fn disable_peer(&self, peer: PeerId) {
+		assert_eq!(self, &Expect::Punish(peer));
+	}
+
+	fn protocol_version(&self, _peer: PeerId) -> Option<u8> {
+		Some(super::MAX_PROTOCOL_VERSION)
+	}
+}
+
+// can't implement directly for Arc due to cross-crate orphan rules.
+struct TestProvider(Arc<TestProviderInner>);
+
+struct TestProviderInner {
+	client: TestBlockChainClient,
+}
+
+impl Provider for TestProvider {
+	fn chain_info(&self) -> BlockChainInfo {
+		self.0.client.chain_info()
+	}
+
+	fn reorg_depth(&self, a: &H256, b: &H256) -> Option<u64> {
+		self.0.client.tree_route(a, b).map(|route| route.index as u64)
+	}
+
+	fn earliest_state(&self) -> Option<u64> {
+		None
+	}
+
+	fn block_headers(&self, req: request::Headers) -> Vec<Bytes> {
+		let best_num = self.0.client.chain_info().best_block_number;
+		let start_num = req.block_num;
+
+		match self.0.client.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 + 1))
+			.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.0.client.block_header(BlockID::Number(x))) 
+			.take_while(|x| x.is_some())
+			.flat_map(|x| x)
+			.collect()
+	}
+
+	fn block_bodies(&self, req: request::Bodies) -> Vec<Bytes> {
+		req.block_hashes.into_iter()
+			.map(|hash| self.0.client.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.0.client.block_receipts(&hash))
+			.map(|receipts| receipts.unwrap_or_else(|| ::rlp::EMPTY_LIST_RLP.to_vec()))
+			.collect()
+	}
+
+	fn proofs(&self, req: request::StateProofs) -> Vec<Bytes> {
+		req.requests.into_iter()
+			.map(|req| {
+				match req.key2 {
+					Some(_) => ::util::sha3::SHA3_NULL_RLP.to_vec(),
+					None => {
+						// sort of a leaf node
+						let mut stream = RlpStream::new_list(2);
+						stream.append(&req.key1).append_empty_data();
+						stream.out()
+					}
+				}
+			})
+			.collect()		
+	}
+
+	fn contract_code(&self, req: request::ContractCodes) -> Vec<Bytes> {
+		req.code_requests.into_iter()
+			.map(|req| { 
+                req.account_key.iter().chain(req.account_key.iter()).cloned().collect()
+			 })
+			.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> {
+		self.0.client.pending_transactions()
+	}
+}
+
+fn make_flow_params() -> FlowParams {
+	FlowParams::new(5_000_000.into(), Default::default(), 100_000.into())
+}
+
+fn capabilities() -> Capabilities {
+	Capabilities {
+		serve_headers: true,
+		serve_chain_since: Some(1),
+		serve_state_since: Some(1),
+		tx_relay: true,
+	}
+}
+
+// helper for setting up the protocol handler and provider.
+fn setup(flow_params: FlowParams, capabilities: Capabilities) -> (Arc<TestProviderInner>, LightProtocol) {
+	let provider = Arc::new(TestProviderInner {
+		client: TestBlockChainClient::new(),
+	});
+
+	let proto = LightProtocol::new(Arc::new(TestProvider(provider.clone())), Params {
+		network_id: 2,
+		flow_params: flow_params,
+		capabilities: capabilities,
+	});
+
+	(provider, proto)
+}
+
+fn status(chain_info: BlockChainInfo) -> Status {
+	Status {
+		protocol_version: 1,
+		network_id: 2,
+		head_td: chain_info.total_difficulty,
+		head_hash: chain_info.best_block_hash,
+		head_num: chain_info.best_block_number,
+		genesis_hash: chain_info.genesis_hash,
+		last_head: None,
+	}
+}
+
+#[test]
+fn handshake_expected() {
+	let flow_params = make_flow_params();
+	let capabilities = capabilities();	
+
+	let (provider, proto) = setup(flow_params.clone(), capabilities.clone());	
+
+	let status = status(provider.client.chain_info());
+
+	let packet_body = write_handshake(&status, &capabilities, Some(&flow_params));
+
+	proto.on_connect(&1, &Expect::Send(1, packet::STATUS, packet_body));
+}
+
+#[test]
+#[should_panic]
+fn genesis_mismatch() {
+	let flow_params = make_flow_params();
+	let capabilities = capabilities();	
+
+	let (provider, proto) = setup(flow_params.clone(), capabilities.clone());	
+
+	let mut status = status(provider.client.chain_info());
+	status.genesis_hash = H256::default();
+
+	let packet_body = write_handshake(&status, &capabilities, Some(&flow_params));
+
+	proto.on_connect(&1, &Expect::Send(1, packet::STATUS, packet_body));
+}
+
+#[test]
+fn buffer_overflow() {
+	let flow_params = make_flow_params();
+	let capabilities = capabilities();	
+
+	let (provider, proto) = setup(flow_params.clone(), capabilities.clone());	
+
+	let status = status(provider.client.chain_info());
+
+	{
+		let packet_body = write_handshake(&status, &capabilities, Some(&flow_params));	
+		proto.on_connect(&1, &Expect::Send(1, packet::STATUS, packet_body));	
+	}
+
+	{
+		let my_status = write_handshake(&status, &capabilities, Some(&flow_params));
+		proto.handle_packet(&Expect::Nothing, &1, packet::STATUS, &my_status);
+	}
+
+	// 1000 requests is far too many for the default flow params.
+	let request = encode_request(&Request::Headers(Headers {
+		block_num: 1,
+		block_hash: provider.client.chain_info().genesis_hash,
+		max: 1000,
+		skip: 0,
+		reverse: false,
+	}), 111);
+
+	proto.handle_packet(&Expect::Punish(1), &1, packet::GET_BLOCK_HEADERS, &request);
+}
+
+// test the basic request types -- these just make sure that requests are parsed
+// and sent to the provider correctly as well as testing response formatting.
+
+#[test]
+fn get_block_headers() {
+	let flow_params = FlowParams::new(5_000_000.into(), Default::default(), 0.into());
+	let capabilities = capabilities();	
+
+	let (provider, proto) = setup(flow_params.clone(), capabilities.clone());	
+
+	let cur_status = status(provider.client.chain_info());
+	let my_status = write_handshake(&cur_status, &capabilities, Some(&flow_params));
+
+	provider.client.add_blocks(100, EachBlockWith::Nothing);
+
+	let cur_status = status(provider.client.chain_info());
+
+	{
+		let packet_body = write_handshake(&cur_status, &capabilities, Some(&flow_params));	
+		proto.on_connect(&1, &Expect::Send(1, packet::STATUS, packet_body));	
+		proto.handle_packet(&Expect::Nothing, &1, packet::STATUS, &my_status);
+	}
+
+	let request = Headers {
+		block_num: 1,
+		block_hash: provider.client.block_hash(BlockID::Number(1)).unwrap(),
+		max: 10,
+		skip: 0,
+		reverse: false,
+	};
+	let req_id = 111;
+
+	let request_body = encode_request(&Request::Headers(request.clone()), req_id);
+	let response = {
+		let headers: Vec<_> = (0..10).map(|i| provider.client.block_header(BlockID::Number(i + 1)).unwrap()).collect();
+		assert_eq!(headers.len(), 10);
+
+		let new_buf = *flow_params.limit() - flow_params.compute_cost(request::Kind::Headers, 10);
+
+		let mut response_stream = RlpStream::new_list(12);
+		
+		response_stream.append(&req_id).append(&new_buf);
+		for header in headers {
+			response_stream.append_raw(&header, 1);
+		}
+
+		response_stream.out()
+	};
+
+	let expected = Expect::Respond(packet::BLOCK_HEADERS, response);
+	proto.handle_packet(&expected, &1, packet::GET_BLOCK_HEADERS, &request_body);
+}
+
+#[test]
+fn get_block_bodies() {
+	let flow_params = FlowParams::new(5_000_000.into(), Default::default(), 0.into());
+	let capabilities = capabilities();	
+
+	let (provider, proto) = setup(flow_params.clone(), capabilities.clone());	
+
+	let cur_status = status(provider.client.chain_info());
+	let my_status = write_handshake(&cur_status, &capabilities, Some(&flow_params));
+
+	provider.client.add_blocks(100, EachBlockWith::Nothing);
+
+	let cur_status = status(provider.client.chain_info());
+
+	{
+		let packet_body = write_handshake(&cur_status, &capabilities, Some(&flow_params));	
+		proto.on_connect(&1, &Expect::Send(1, packet::STATUS, packet_body));	
+		proto.handle_packet(&Expect::Nothing, &1, packet::STATUS, &my_status);
+	}
+
+	let request = request::Bodies {
+		block_hashes: (0..10).map(|i| provider.client.block_hash(BlockID::Number(i)).unwrap()).collect(),
+	};
+
+	let req_id = 111;
+
+	let request_body = encode_request(&Request::Bodies(request.clone()), req_id);
+	let response = {
+		let bodies: Vec<_> = (0..10).map(|i| provider.client.block_body(BlockID::Number(i + 1)).unwrap()).collect();
+		assert_eq!(bodies.len(), 10);
+
+		let new_buf = *flow_params.limit() - flow_params.compute_cost(request::Kind::Bodies, 10);
+
+		let mut response_stream = RlpStream::new_list(12);
+		
+		response_stream.append(&req_id).append(&new_buf);
+		for body in bodies {
+			response_stream.append_raw(&body, 1);
+		}
+
+		response_stream.out()
+	};
+
+	let expected = Expect::Respond(packet::BLOCK_BODIES, response);
+	proto.handle_packet(&expected, &1, packet::GET_BLOCK_BODIES, &request_body);
+}
+
+#[test]
+fn get_block_receipts() {
+	let flow_params = FlowParams::new(5_000_000.into(), Default::default(), 0.into());
+	let capabilities = capabilities();	
+
+	let (provider, proto) = setup(flow_params.clone(), capabilities.clone());	
+
+	let cur_status = status(provider.client.chain_info());
+	let my_status = write_handshake(&cur_status, &capabilities, Some(&flow_params));
+
+	provider.client.add_blocks(1000, EachBlockWith::Nothing);
+
+	let cur_status = status(provider.client.chain_info());
+
+	{
+		let packet_body = write_handshake(&cur_status, &capabilities, Some(&flow_params));	
+		proto.on_connect(&1, &Expect::Send(1, packet::STATUS, packet_body));	
+		proto.handle_packet(&Expect::Nothing, &1, packet::STATUS, &my_status);
+	}
+
+	// find the first 10 block hashes starting with `f` because receipts are only provided
+	// by the test client in that case.
+	let block_hashes: Vec<_> = (0..1000).map(|i| provider.client.block_hash(BlockID::Number(i)).unwrap())
+		.filter(|hash| format!("{}", hash).starts_with("f")).take(10).collect();
+
+	let request = request::Receipts {
+		block_hashes: block_hashes.clone(),
+	};
+
+	let req_id = 111;
+
+	let request_body = encode_request(&Request::Receipts(request.clone()), req_id);
+	let response = {
+		let receipts: Vec<_> = block_hashes.iter()
+			.map(|hash| provider.client.block_receipts(hash).unwrap())
+			.collect();
+
+		let new_buf = *flow_params.limit() - flow_params.compute_cost(request::Kind::Receipts, receipts.len());
+
+		let mut response_stream = RlpStream::new_list(2 + receipts.len());
+		
+		response_stream.append(&req_id).append(&new_buf);
+		for block_receipts in receipts {
+			response_stream.append_raw(&block_receipts, 1);
+		}
+
+		response_stream.out()
+	};
+
+	let expected = Expect::Respond(packet::RECEIPTS, response);
+	proto.handle_packet(&expected, &1, packet::GET_RECEIPTS, &request_body);
+}
+
+#[test]
+fn get_state_proofs() {
+	let flow_params = FlowParams::new(5_000_000.into(), Default::default(), 0.into());
+	let capabilities = capabilities();	
+
+	let (provider, proto) = setup(flow_params.clone(), capabilities.clone());	
+
+	let cur_status = status(provider.client.chain_info());
+
+	{
+		let packet_body = write_handshake(&cur_status, &capabilities, Some(&flow_params));	
+		proto.on_connect(&1, &Expect::Send(1, packet::STATUS, packet_body.clone()));	
+		proto.handle_packet(&Expect::Nothing, &1, packet::STATUS, &packet_body);
+	}
+
+	let req_id = 112;
+	let key1 = U256::from(11223344).into();
+	let key2 = U256::from(99988887).into();
+
+	let request = Request::StateProofs (request::StateProofs { 
+		requests: vec![
+			request::StateProof { block: H256::default(), key1: key1, key2: None, from_level: 0 },
+			request::StateProof { block: H256::default(), key1: key1, key2: Some(key2), from_level: 0},
+		]
+	});
+
+	let request_body = encode_request(&request, req_id);
+	let response = {
+		let proofs = vec![
+			{ let mut stream = RlpStream::new_list(2); stream.append(&key1).append_empty_data(); stream.out() },
+			::util::sha3::SHA3_NULL_RLP.to_vec(),
+		];
+
+		let new_buf = *flow_params.limit() - flow_params.compute_cost(request::Kind::StateProofs, 2);
+
+		let mut response_stream = RlpStream::new_list(4);
+		
+		response_stream.append(&req_id).append(&new_buf);
+		for proof in proofs {
+			response_stream.append_raw(&proof, 1);
+		}
+
+		response_stream.out()
+	};
+
+	let expected = Expect::Respond(packet::PROOFS, response);
+	proto.handle_packet(&expected, &1, packet::GET_PROOFS, &request_body);
+}
+
+#[test]
+fn get_contract_code() {
+	let flow_params = FlowParams::new(5_000_000.into(), Default::default(), 0.into());
+	let capabilities = capabilities();	
+
+	let (provider, proto) = setup(flow_params.clone(), capabilities.clone());	
+
+	let cur_status = status(provider.client.chain_info());
+
+	{
+		let packet_body = write_handshake(&cur_status, &capabilities, Some(&flow_params));	
+		proto.on_connect(&1, &Expect::Send(1, packet::STATUS, packet_body.clone()));	
+		proto.handle_packet(&Expect::Nothing, &1, packet::STATUS, &packet_body);
+	}
+
+	let req_id = 112;
+	let key1 = U256::from(11223344).into();
+	let key2 = U256::from(99988887).into();
+
+	let request = Request::Codes (request::ContractCodes { 
+		code_requests: vec![
+			request::ContractCode { block_hash: H256::default(), account_key: key1 },
+			request::ContractCode { block_hash: H256::default(), account_key: key2 },
+		],
+	});
+
+	let request_body = encode_request(&request, req_id);
+	let response = {
+		let codes: Vec<Vec<_>> = vec![
+			key1.iter().chain(key1.iter()).cloned().collect(),
+            key2.iter().chain(key2.iter()).cloned().collect(),
+		];
+
+		let new_buf = *flow_params.limit() - flow_params.compute_cost(request::Kind::Codes, 2);
+
+		let mut response_stream = RlpStream::new_list(4);
+		
+		response_stream.append(&req_id).append(&new_buf);
+		for code in codes {
+			response_stream.append(&code);
+		}
+
+		response_stream.out()
+	};
+
+	let expected = Expect::Respond(packet::CONTRACT_CODES, response);
+	proto.handle_packet(&expected, &1, packet::GET_CONTRACT_CODES, &request_body);
+}

ethcore/light/src/provider.rs

@@ -33,6 +33,7 @@ use request;
 /// or empty vector where appropriate.
 ///
 /// [1]: https://github.com/ethcore/parity/wiki/Light-Ethereum-Subprotocol-(LES)
+#[cfg_attr(feature = "ipc", ipc(client_ident="LightProviderClient"))]
 pub trait Provider: Send + Sync {
 	/// Provide current blockchain info.
 	fn chain_info(&self) -> BlockChainInfo;
@@ -71,7 +72,10 @@ pub trait Provider: Send + Sync {
 	/// Each item in the resulting vector is either the raw bytecode or empty.
 	fn contract_code(&self, req: request::ContractCodes) -> Vec<Bytes>;
 
-	/// Provide header proofs from the Canonical Hash Tries.
+	/// Provide header proofs from the Canonical Hash Tries as well as the headers 
+	/// they correspond to -- each element in the returned vector is a 2-tuple.
+	/// The first element is a block header and the second a merkle proof of 
+	/// the header in a requested CHT.
 	fn header_proofs(&self, req: request::HeaderProofs) -> Vec<Bytes>;
 
 	/// Provide pending transactions.
@@ -105,8 +109,8 @@ impl<T: ProvingBlockChainClient + ?Sized> Provider for T {
 		}
 
 		(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: u64| x.saturating_mul(req.skip + 1))
+			.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)))
 			.take_while(|x| x.is_some())

ethcore/light/src/types/les_request.rs

@@ -19,7 +19,8 @@
 use util::H256;
 
 /// A request for block headers.
-#[derive(Debug, Clone, PartialEq, Eq, Binary)]
+#[derive(Debug, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "ipc", derive(Binary))]
 pub struct Headers {
 	/// Starting block number
 	pub block_num: u64,
@@ -35,7 +36,8 @@ pub struct Headers {
 }
 
 /// A request for specific block bodies.
-#[derive(Debug, Clone, PartialEq, Eq, Binary)]
+#[derive(Debug, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "ipc", derive(Binary))]
 pub struct Bodies {
 	/// Hashes which bodies are being requested for.
 	pub block_hashes: Vec<H256>
@@ -45,14 +47,16 @@ pub struct Bodies {
 ///
 /// This request is answered with a list of transaction receipts for each block
 /// requested.
-#[derive(Debug, Clone, PartialEq, Eq, Binary)]
+#[derive(Debug, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "ipc", derive(Binary))]
 pub struct Receipts {
 	/// Block hashes to return receipts for.
 	pub block_hashes: Vec<H256>,
 }
 
 /// A request for a state proof
-#[derive(Debug, Clone, PartialEq, Eq, Binary)]
+#[derive(Debug, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "ipc", derive(Binary))]
 pub struct StateProof {
 	/// Block hash to query state from.
 	pub block: H256,
@@ -66,14 +70,16 @@ pub struct StateProof {
 }
 
 /// A request for state proofs.
-#[derive(Debug, Clone, PartialEq, Eq, Binary)]
+#[derive(Debug, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "ipc", derive(Binary))]
 pub struct StateProofs {
 	/// All the proof requests.
 	pub requests: Vec<StateProof>,
 }
 
 /// A request for contract code.
-#[derive(Debug, Clone, PartialEq, Eq, Binary)]
+#[derive(Debug, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "ipc", derive(Binary))]
 pub struct ContractCode {
 	/// Block hash
 	pub block_hash: H256,
@@ -82,14 +88,16 @@ pub struct ContractCode {
 }
 
 /// A request for contract code.
-#[derive(Debug, Clone, PartialEq, Eq, Binary)]
+#[derive(Debug, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "ipc", derive(Binary))]
 pub struct ContractCodes {
 	/// Block hash and account key (== sha3(address)) pairs to fetch code for.
 	pub code_requests: Vec<ContractCode>,
 }
 
 /// A request for a header proof from the Canonical Hash Trie.
-#[derive(Debug, Clone, PartialEq, Eq, Binary)]
+#[derive(Debug, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "ipc", derive(Binary))]
 pub struct HeaderProof {
 	/// Number of the CHT.
 	pub cht_number: u64,
@@ -100,14 +108,16 @@ pub struct HeaderProof {
 }
 
 /// A request for header proofs from the CHT.
-#[derive(Debug, Clone, PartialEq, Eq, Binary)]
+#[derive(Debug, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "ipc", derive(Binary))]
 pub struct HeaderProofs {
 	/// All the proof requests.
 	pub requests: Vec<HeaderProof>,
 }
 
 /// Kinds of requests.
-#[derive(Debug, Clone, Copy, PartialEq, Eq, Binary)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[cfg_attr(feature = "ipc", derive(Binary))]
 pub enum Kind {
 	/// Requesting headers.
 	Headers,
@@ -124,7 +134,8 @@ pub enum Kind {
 }
 
 /// Encompasses all possible types of requests in a single structure.
-#[derive(Debug, Clone, PartialEq, Eq, Binary)]
+#[derive(Debug, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "ipc", derive(Binary))]
 pub enum Request {
 	/// Requesting headers.
 	Headers(Headers),

ethcore/light/src/types/mod.rs

@@ -15,6 +15,11 @@
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.
 
 //! Types used in the public (IPC) api which require custom code generation.
+#![cfg_attr(feature = "ipc", allow(dead_code, unused_assignments, unused_variables))] // codegen issues
 
-#![allow(dead_code, unused_assignments, unused_variables)] // codegen issues
+
+#[cfg(feature = "ipc")]
 include!(concat!(env!("OUT_DIR"), "/mod.rs.in"));
+
+#[cfg(not(feature = "ipc"))]
+include!("mod.rs.in");

ethcore/src/client/client.rs

@@ -52,7 +52,7 @@ use blockchain::{BlockChain, BlockProvider, TreeRoute, ImportRoute};
 use client::{
 	BlockID, TransactionID, UncleID, TraceId, ClientConfig, BlockChainClient,
 	MiningBlockChainClient, TraceFilter, CallAnalytics, BlockImportError, Mode,
-	ChainNotify, PruningInfo, ProvingBlockChainClient,
+	ChainNotify, PruningInfo,
 };
 use client::Error as ClientError;
 use env_info::EnvInfo;
@@ -1391,7 +1391,7 @@ impl MayPanic for Client {
 	}
 }
 
-impl ProvingBlockChainClient for Client {
+impl ::client::ProvingBlockChainClient for Client {
 	fn prove_storage(&self, key1: H256, key2: H256, from_level: u32, id: BlockID) -> Vec<Bytes> {
 		self.state_at(id)
 			.and_then(move |state| state.prove_storage(key1, key2, from_level).ok())

ethcore/src/client/mod.rs

@@ -27,7 +27,9 @@ pub use self::config::{Mode, ClientConfig, DatabaseCompactionProfile, BlockChain
 pub use self::error::Error;
 pub use self::test_client::{TestBlockChainClient, EachBlockWith};
 pub use self::chain_notify::ChainNotify;
-pub use self::traits::{BlockChainClient, MiningBlockChainClient, ProvingBlockChainClient};
+pub use self::traits::{BlockChainClient, MiningBlockChainClient};
+
+pub use self::traits::ProvingBlockChainClient;
 
 pub use types::ids::*;
 pub use types::trace_filter::Filter as TraceFilter;

ethcore/src/client/test_client.rs

@@ -92,8 +92,8 @@ pub struct TestBlockChainClient {
 	pub first_block: RwLock<Option<(H256, u64)>>,
 }
 
-#[derive(Clone)]
 /// Used for generating test client blocks.
+#[derive(Clone)]
 pub enum EachBlockWith {
 	/// Plain block.
 	Nothing,

ethcore/src/state/mod.rs

@@ -31,6 +31,7 @@ use transaction::SignedTransaction;
 use state_db::StateDB;
 
 use util::*;
+
 use util::trie::recorder::{Recorder, BasicRecorder as TrieRecorder};
 
 mod account;

parity/cli/config.full.toml

@@ -32,6 +32,7 @@ warp = true
 allow_ips = "all"
 snapshot_peers = 0
 max_pending_peers = 64
+serve_light = true
 
 reserved_only = false
 reserved_peers = "./path_to_file"

parity/cli/mod.rs

@@ -135,6 +135,8 @@ usage! {
 		flag_reserved_only: bool = false,
 			or |c: &Config| otry!(c.network).reserved_only.clone(),
 		flag_no_ancient_blocks: bool = false, or |_| None,
+		flag_serve_light: bool = false,
+			or |c: &Config| otry!(c.network).serve_light.clone(),
 
 		// -- API and Console Options
 		// RPC
@@ -340,6 +342,7 @@ struct Network {
 	node_key: Option<String>,
 	reserved_peers: Option<String>,
 	reserved_only: Option<bool>,
+	serve_light: Option<bool>,
 }
 
 #[derive(Default, Debug, PartialEq, RustcDecodable)]
@@ -552,6 +555,7 @@ mod tests {
 			flag_reserved_peers: Some("./path_to_file".into()),
 			flag_reserved_only: false,
 			flag_no_ancient_blocks: false,
+			flag_serve_light: true,
 
 			// -- API and Console Options
 			// RPC
@@ -725,6 +729,7 @@ mod tests {
 				node_key: None,
 				reserved_peers: Some("./path/to/reserved_peers".into()),
 				reserved_only: Some(true),
+				serve_light: None,
 			}),
 			rpc: Some(Rpc {
 				disable: Some(true),

parity/cli/usage.txt

@@ -97,6 +97,7 @@ Networking Options:
   --max-pending-peers NUM  Allow up to NUM pending connections. (default: {flag_max_pending_peers})
   --no-ancient-blocks      Disable downloading old blocks after snapshot restoration
                            or warp sync. (default: {flag_no_ancient_blocks})
+  --serve-light            Experimental: Serve light client peers. (default: {flag_serve_light})
 
 API and Console Options:
   --no-jsonrpc             Disable the JSON-RPC API server. (default: {flag_no_jsonrpc})

parity/configuration.rs

@@ -279,6 +279,7 @@ impl Configuration {
 				no_periodic_snapshot: self.args.flag_no_periodic_snapshot,
 				check_seal: !self.args.flag_no_seal_check,
 				download_old_blocks: !self.args.flag_no_ancient_blocks,
+				serve_light: self.args.flag_serve_light,
 				verifier_settings: verifier_settings,
 			};
 			Cmd::Run(run_cmd)
@@ -942,6 +943,7 @@ mod tests {
 			no_periodic_snapshot: false,
 			check_seal: true,
 			download_old_blocks: true,
+			serve_light: false,
 			verifier_settings: Default::default(),
 		}));
 	}

parity/main.rs

@@ -43,6 +43,7 @@ extern crate serde;
 extern crate serde_json;
 extern crate rlp;
 extern crate ethcore_hash_fetch as hash_fetch;
+extern crate ethcore_light as light;
 
 extern crate ethcore_ipc_hypervisor as hypervisor;
 extern crate ethcore_rpc;

parity/modules.rs

@@ -15,16 +15,22 @@
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.
 
 use std::sync::Arc;
+use std::path::Path;
+
 use ethcore::client::BlockChainClient;
 use hypervisor::Hypervisor;
-use ethsync::{SyncConfig, NetworkConfiguration, NetworkError};
+use ethsync::{SyncConfig, NetworkConfiguration, NetworkError, Params};
 use ethcore::snapshot::SnapshotService;
+use light::Provider;
+
 #[cfg(not(feature="ipc"))]
 use self::no_ipc_deps::*;
+
+#[cfg(not(feature="ipc"))]
+use ethcore_logger::Config as LogConfig;
+
 #[cfg(feature="ipc")]
 use self::ipc_deps::*;
-use ethcore_logger::Config as LogConfig;
-use std::path::Path;
 
 #[cfg(feature="ipc")]
 pub mod service_urls {
@@ -36,6 +42,8 @@ pub mod service_urls {
 	pub const SYNC_NOTIFY: &'static str = "parity-sync-notify.ipc";
 	pub const NETWORK_MANAGER: &'static str = "parity-manage-net.ipc";
 	pub const SYNC_CONTROL: &'static str = "parity-sync-control.ipc";
+	pub const LIGHT_PROVIDER: &'static str = "parity-light-provider.ipc";
+
 	#[cfg(feature="stratum")]
 	pub const STRATUM: &'static str = "parity-stratum.ipc";
 	#[cfg(feature="stratum")]
@@ -75,6 +83,7 @@ mod ipc_deps {
 	pub use nanoipc::{GuardedSocket, NanoSocket, generic_client, fast_client};
 	pub use ipc::IpcSocket;
 	pub use ipc::binary::serialize;
+	pub use light::remote::LightProviderClient;
 }
 
 #[cfg(feature="ipc")]
@@ -124,6 +133,7 @@ pub fn sync
 		net_cfg: NetworkConfiguration,
 		_client: Arc<BlockChainClient>,
 		_snapshot_service: Arc<SnapshotService>,
+		_provider: Arc<Provider>,		
 		log_settings: &LogConfig,
 	)
 	-> Result<SyncModules, NetworkError>
@@ -141,6 +151,8 @@ pub fn sync
 		&service_urls::with_base(&hypervisor.io_path, service_urls::SYNC_NOTIFY)).unwrap();
 	let manage_client = generic_client::<NetworkManagerClient<_>>(
 		&service_urls::with_base(&hypervisor.io_path, service_urls::NETWORK_MANAGER)).unwrap();
+	let provider_client = generic_client::<LightProviderClient<_>>(
+		&service_urls::with_base(&hypervisor.io_path, service_urls::LIGHT_PROVIDER)).unwrap();
 		
 	*hypervisor_ref = Some(hypervisor);
 	Ok((sync_client, manage_client, notify_client))
@@ -154,10 +166,18 @@ pub fn sync
 		net_cfg: NetworkConfiguration,
 		client: Arc<BlockChainClient>,
 		snapshot_service: Arc<SnapshotService>,
+		provider: Arc<Provider>,		
 		_log_settings: &LogConfig,
 	)
 	-> Result<SyncModules, NetworkError>
 {
-	let eth_sync = try!(EthSync::new(sync_cfg, client, snapshot_service, net_cfg));
+	let eth_sync = try!(EthSync::new(Params {
+		config: sync_cfg, 
+		chain: client,
+		provider: provider,
+		snapshot_service: snapshot_service, 
+		network_config: net_cfg,
+	}));
+
 	Ok((eth_sync.clone() as Arc<SyncProvider>, eth_sync.clone() as Arc<ManageNetwork>, eth_sync.clone() as Arc<ChainNotify>))
 }

parity/run.rs

@@ -93,6 +93,7 @@ pub struct RunCmd {
 	pub no_periodic_snapshot: bool,
 	pub check_seal: bool,
 	pub download_old_blocks: bool,
+	pub serve_light: bool,
 	pub verifier_settings: VerifierSettings,
 }
 
@@ -187,6 +188,11 @@ pub fn execute(cmd: RunCmd, logger: Arc<RotatingLogger>) -> Result<(), String> {
 	);
 	info!("Operating mode: {}", Colour::White.bold().paint(format!("{}", mode)));
 
+	if cmd.serve_light {
+		info!("Configured to serve light client peers. Please note this feature is {}.",
+			Colour::White.bold().paint("experimental".to_string()));
+	}
+
 	// display warning about using experimental journaldb alorithm
 	if !algorithm.is_stable() {
 		warn!("Your chosen strategy is {}! You can re-run with --pruning to change.", Colour::Red.bold().paint("unstable"));
@@ -206,6 +212,7 @@ pub fn execute(cmd: RunCmd, logger: Arc<RotatingLogger>) -> Result<(), String> {
 	sync_config.fork_block = spec.fork_block();
 	sync_config.warp_sync = cmd.warp_sync;
 	sync_config.download_old_blocks = cmd.download_old_blocks;
+	sync_config.serve_light = cmd.serve_light;
 
 	let passwords = try!(passwords_from_files(&cmd.acc_conf.password_files));
 
@@ -283,7 +290,13 @@ pub fn execute(cmd: RunCmd, logger: Arc<RotatingLogger>) -> Result<(), String> {
 
 	// create sync object
 	let (sync_provider, manage_network, chain_notify) = try!(modules::sync(
-		&mut hypervisor, sync_config, net_conf.into(), client.clone(), snapshot_service.clone(), &cmd.logger_config,
+		&mut hypervisor, 
+		sync_config, 
+		net_conf.into(), 
+		client.clone(), 
+		snapshot_service.clone(), 
+		client.clone(), 
+		&cmd.logger_config,
 	).map_err(|e| format!("Sync error: {}", e)));
 
 	service.add_notify(chain_notify.clone());

parity/sync.rs

@@ -22,6 +22,7 @@ use hypervisor::{SYNC_MODULE_ID, HYPERVISOR_IPC_URL, ControlService};
 use ethcore::client::ChainNotify;
 use ethcore::client::remote::RemoteClient;
 use ethcore::snapshot::remote::RemoteSnapshotService;
+use light::remote::LightProviderClient;
 use ethsync::{SyncProvider, EthSync, ManageNetwork, ServiceConfiguration};
 use modules::service_urls;
 use boot;
@@ -48,8 +49,15 @@ pub fn main() {
 
 	let remote_client = dependency!(RemoteClient, &service_urls::with_base(&service_config.io_path, service_urls::CLIENT));
 	let remote_snapshot = dependency!(RemoteSnapshotService, &service_urls::with_base(&service_config.io_path, service_urls::SNAPSHOT));
+	let remote_provider = dependency!(LightProviderClient, &service_urls::with_base(&service_config.io_path, service_urls::LIGHT_PROVIDER));
 
-	let sync = EthSync::new(service_config.sync, remote_client.service().clone(), remote_snapshot.service().clone(), service_config.net).unwrap();
+	let sync = EthSync::new(Params {
+		config: service_config.sync, 
+		chain: remote_client.service().clone(), 
+		snapshot_service: remote_snapshot.service().clone(), 
+		provider: remote_provider.service().clone(),
+		network_config: service_config.net
+	}).unwrap();
 
 	let _ = boot::main_thread();
 	let service_stop = Arc::new(AtomicBool::new(false));

scripts/targets.sh

@@ -17,4 +17,5 @@ export TARGETS="
 	-p ethcore-ipc \
 	-p ethcore-ipc-tests \
 	-p ethcore-ipc-nano \
+	-p ethcore-light \
 	-p parity"

sync/Cargo.toml

@@ -15,6 +15,7 @@ ethcore-ipc-codegen = { path = "../ipc/codegen" }
 ethcore-util = { path = "../util" }
 ethcore-network = { path = "../util/network" }
 ethcore-io = { path = "../util/io" }
+ethcore-light = { path = "../ethcore/light"}
 ethcore = { path = "../ethcore" }
 rlp = { path = "../util/rlp" }
 clippy = { version = "0.0.103", optional = true}
@@ -31,6 +32,6 @@ ethkey = { path = "../ethkey" }
 parking_lot = "0.3"
 
 [features]
-default = ["ipc"]
+default = []
 dev = ["clippy", "ethcore/dev", "ethcore-util/dev"]
-ipc = []
+ipc = ["ethcore-light/ipc"]

sync/build.rs

@@ -16,6 +16,10 @@
 
 extern crate ethcore_ipc_codegen;
 
+#[cfg(feature = "ipc")]
 fn main() {
-	ethcore_ipc_codegen::derive_ipc_cond("src/api.rs", cfg!(feature="ipc")).unwrap();
+	ethcore_ipc_codegen::derive_ipc_cond("src/api.rs", true).unwrap();
 }
+
+#[cfg(not(feature = "ipc"))]
+fn main() {}

sync/src/api.rs

@@ -33,6 +33,7 @@ use ipc::{BinaryConvertable, BinaryConvertError, IpcConfig};
 use std::str::FromStr;
 use parking_lot::RwLock;
 use chain::{ETH_PACKET_COUNT, SNAPSHOT_SYNC_PACKET_COUNT};
+use light::net::{LightProtocol, Params as LightParams, Capabilities, Handler as LightHandler, EventContext};
 
 pub const WARP_SYNC_PROTOCOL_ID: ProtocolId = *b"par";
 
@@ -47,10 +48,14 @@ pub struct SyncConfig {
 	pub network_id: u64,
 	/// Main "eth" subprotocol name.
 	pub subprotocol_name: [u8; 3],
+	/// Light "les" subprotocol name.
+	pub light_subprotocol_name: [u8; 3],
 	/// Fork block to check
 	pub fork_block: Option<(BlockNumber, H256)>,
 	/// Enable snapshot sync
 	pub warp_sync: bool,
+	/// Enable light client server.
+	pub serve_light: bool,
 }
 
 impl Default for SyncConfig {
@@ -60,8 +65,10 @@ impl Default for SyncConfig {
 			download_old_blocks: true,
 			network_id: 1,
 			subprotocol_name: *b"eth",
+			light_subprotocol_name: *b"les",
 			fork_block: None,
 			warp_sync: false,
+			serve_light: false,
 		}
 	}
 }
@@ -85,14 +92,18 @@ pub trait SyncProvider: Send + Sync {
 }
 
 /// Transaction stats
-#[derive(Debug, Binary)]
+#[derive(Debug)]
+#[cfg_attr(feature = "ipc", derive(Binary))]
 pub struct TransactionStats {
+	/// Block number where this TX was first seen.
 	pub first_seen: u64,
+	/// Peers it was propagated to.
 	pub propagated_to: BTreeMap<H512, usize>,
 }
 
 /// Peer connection information
-#[derive(Debug, Binary)]
+#[derive(Debug)]
+#[cfg_attr(feature = "ipc", derive(Binary))]
 pub struct PeerInfo {
 	/// Public node id
 	pub id: Option<String>,
@@ -112,51 +123,93 @@ pub struct PeerInfo {
 	pub eth_difficulty: Option<U256>,
 }
 
+/// EthSync initialization parameters.
+#[cfg_attr(feature = "ipc", derive(Binary))]
+pub struct Params {
+	/// Configuration.
+	pub config: SyncConfig,
+	/// Blockchain client.
+	pub chain: Arc<BlockChainClient>,
+	/// Snapshot service.
+	pub snapshot_service: Arc<SnapshotService>,
+	/// Light data provider.
+	pub provider: Arc<::light::Provider>,
+	/// Network layer configuration.
+	pub network_config: NetworkConfiguration,
+}
+
 /// Ethereum network protocol handler
 pub struct EthSync {
 	/// Network service
 	network: NetworkService,
-	/// Protocol handler
-	handler: Arc<SyncProtocolHandler>,
+	/// Main (eth/par) protocol handler
+	sync_handler: Arc<SyncProtocolHandler>,
+	/// Light (les) protocol handler 
+	light_proto: Option<Arc<LightProtocol>>,
 	/// The main subprotocol name
 	subprotocol_name: [u8; 3],
-	/// Configuration
-	config: NetworkConfiguration,
+	/// Light subprotocol name.
+	light_subprotocol_name: [u8; 3],
 }
 
 impl EthSync {
 	/// Creates and register protocol with the network service
-	pub fn new(config: SyncConfig, chain: Arc<BlockChainClient>, snapshot_service: Arc<SnapshotService>, network_config: NetworkConfiguration) -> Result<Arc<EthSync>, NetworkError> {
-		let chain_sync = ChainSync::new(config, &*chain);
-		let service = try!(NetworkService::new(try!(network_config.clone().into_basic())));
-		let sync = Arc::new(EthSync{
+	pub fn new(params: Params) -> Result<Arc<EthSync>, NetworkError> {
+		let pruning_info = params.chain.pruning_info();		
+		let light_proto = match params.config.serve_light {
+			false => None,
+			true => Some({
+				let light_params = LightParams {
+					network_id: params.config.network_id,
+					flow_params: Default::default(),
+					capabilities: Capabilities {
+						serve_headers: true,
+						serve_chain_since: Some(pruning_info.earliest_chain),
+						serve_state_since: Some(pruning_info.earliest_state),
+						tx_relay: true,
+					},
+				};
+
+				let mut light_proto = LightProtocol::new(params.provider, light_params);
+				light_proto.add_handler(Box::new(TxRelay(params.chain.clone())));
+
+				Arc::new(light_proto)
+			})
+		};
+
+		let chain_sync = ChainSync::new(params.config, &*params.chain);
+		let service = try!(NetworkService::new(try!(params.network_config.clone().into_basic())));
+
+		let sync = Arc::new(EthSync {
 			network: service,
-			handler: Arc::new(SyncProtocolHandler {
+			sync_handler: Arc::new(SyncProtocolHandler {
 				sync: RwLock::new(chain_sync),
-				chain: chain,
-				snapshot_service: snapshot_service,
+				chain: params.chain,
+				snapshot_service: params.snapshot_service,
 				overlay: RwLock::new(HashMap::new()),
 			}),
-			subprotocol_name: config.subprotocol_name,
-			config: network_config,
+			light_proto: light_proto,
+			subprotocol_name: params.config.subprotocol_name,
+			light_subprotocol_name: params.config.light_subprotocol_name,
 		});
 
 		Ok(sync)
 	}
 }
 
-#[ipc(client_ident="SyncClient")]
+#[cfg_attr(feature = "ipc", ipc(client_ident="SyncClient"))]
 impl SyncProvider for EthSync {
 	/// Get sync status
 	fn status(&self) -> SyncStatus {
-		self.handler.sync.write().status()
+		self.sync_handler.sync.write().status()
 	}
 
 	/// Get sync peers
 	fn peers(&self) -> Vec<PeerInfo> {
+		// TODO: [rob] LES peers/peer info
 		self.network.with_context_eval(self.subprotocol_name, |context| {
-			let sync_io = NetSyncIo::new(context, &*self.handler.chain, &*self.handler.snapshot_service, &self.handler.overlay);
-			self.handler.sync.write().peers(&sync_io)
+			let sync_io = NetSyncIo::new(context, &*self.sync_handler.chain, &*self.sync_handler.snapshot_service, &self.sync_handler.overlay);
+			self.sync_handler.sync.write().peers(&sync_io)
 		}).unwrap_or(Vec::new())
 	}
 
@@ -165,7 +218,7 @@ impl SyncProvider for EthSync {
 	}
 
 	fn transactions_stats(&self) -> BTreeMap<H256, TransactionStats> {
-		let sync = self.handler.sync.read();
+		let sync = self.sync_handler.sync.read();
 		sync.transactions_stats()
 			.iter()
 			.map(|(hash, stats)| (*hash, stats.into()))
@@ -226,9 +279,11 @@ impl ChainNotify for EthSync {
 		sealed: Vec<H256>,
 		_duration: u64)
 	{
+		use light::net::Announcement;
+
 		self.network.with_context(self.subprotocol_name, |context| {
-			let mut sync_io = NetSyncIo::new(context, &*self.handler.chain, &*self.handler.snapshot_service, &self.handler.overlay);
-			self.handler.sync.write().chain_new_blocks(
+			let mut sync_io = NetSyncIo::new(context, &*self.sync_handler.chain, &*self.sync_handler.snapshot_service, &self.sync_handler.overlay);
+			self.sync_handler.sync.write().chain_new_blocks(
 				&mut sync_io,
 				&imported,
 				&invalid,
@@ -236,6 +291,25 @@ impl ChainNotify for EthSync {
 				&retracted,
 				&sealed);
 		});
+
+		self.network.with_context(self.light_subprotocol_name, |context| {
+			let light_proto = match self.light_proto.as_ref() {
+				Some(lp) => lp,
+				None => return,
+			};
+			
+			let chain_info = self.sync_handler.chain.chain_info();
+			light_proto.make_announcement(context, Announcement {
+				head_hash: chain_info.best_block_hash,
+				head_num: chain_info.best_block_number,
+				head_td: chain_info.total_difficulty,
+				reorg_depth: 0, // recalculated on a per-peer basis.
+				serve_headers: false, // these fields consist of _changes_ in capability.
+				serve_state_since: None,
+				serve_chain_since: None,
+				tx_relay: false,
+			})
+		})
 	}
 
 	fn start(&self) {
@@ -244,19 +318,36 @@ impl ChainNotify for EthSync {
 			Err(err) => warn!("Error starting network: {}", err),
 			_ => {},
 		}
-		self.network.register_protocol(self.handler.clone(), self.subprotocol_name, ETH_PACKET_COUNT, &[62u8, 63u8])
+		self.network.register_protocol(self.sync_handler.clone(), self.subprotocol_name, ETH_PACKET_COUNT, &[62u8, 63u8])
 			.unwrap_or_else(|e| warn!("Error registering ethereum protocol: {:?}", e));
 		// register the warp sync subprotocol
-		self.network.register_protocol(self.handler.clone(), WARP_SYNC_PROTOCOL_ID, SNAPSHOT_SYNC_PACKET_COUNT, &[1u8])
+		self.network.register_protocol(self.sync_handler.clone(), WARP_SYNC_PROTOCOL_ID, SNAPSHOT_SYNC_PACKET_COUNT, &[1u8])
 			.unwrap_or_else(|e| warn!("Error registering snapshot sync protocol: {:?}", e));
+		
+		// register the light protocol.
+		if let Some(light_proto) = self.light_proto.as_ref().map(|x| x.clone()) {
+			self.network.register_protocol(light_proto, self.light_subprotocol_name, ::light::net::PACKET_COUNT, ::light::net::PROTOCOL_VERSIONS)
+				.unwrap_or_else(|e| warn!("Error registering light client protocol: {:?}", e));
+		}
 	}
 
 	fn stop(&self) {
-		self.handler.snapshot_service.abort_restore();
+		self.sync_handler.snapshot_service.abort_restore();
 		self.network.stop().unwrap_or_else(|e| warn!("Error stopping network: {:?}", e));
 	}
 }
 
+/// LES event handler.
+/// Simply queues transactions from light client peers.
+struct TxRelay(Arc<BlockChainClient>);
+
+impl LightHandler for TxRelay {
+	fn on_transactions(&self, ctx: &EventContext, relay: &[::ethcore::transaction::SignedTransaction]) {
+		trace!(target: "les", "Relaying {} transactions from peer {}", relay.len(), ctx.peer());
+		self.0.queue_transactions(relay.iter().map(|tx| ::rlp::encode(tx).to_vec()).collect())
+	}
+}
+
 impl IpcConfig for ManageNetwork { }
 impl IpcConfig for SyncProvider { }
 
@@ -279,7 +370,7 @@ pub trait ManageNetwork : Send + Sync {
 }
 
 
-#[ipc(client_ident="NetworkManagerClient")]
+#[cfg_attr(feature = "ipc", ipc(client_ident="NetworkManagerClient"))]
 impl ManageNetwork for EthSync {
 	fn accept_unreserved_peers(&self) {
 		self.network.set_non_reserved_mode(NonReservedPeerMode::Accept);
@@ -303,9 +394,14 @@ impl ManageNetwork for EthSync {
 
 	fn stop_network(&self) {
 		self.network.with_context(self.subprotocol_name, |context| {
-			let mut sync_io = NetSyncIo::new(context, &*self.handler.chain, &*self.handler.snapshot_service, &self.handler.overlay);
-			self.handler.sync.write().abort(&mut sync_io);
+			let mut sync_io = NetSyncIo::new(context, &*self.sync_handler.chain, &*self.sync_handler.snapshot_service, &self.sync_handler.overlay);
+			self.sync_handler.sync.write().abort(&mut sync_io);
 		});
+
+		if let Some(light_proto) = self.light_proto.as_ref() {
+			light_proto.abort();
+		}
+
 		self.stop();
 	}
 
@@ -315,7 +411,8 @@ impl ManageNetwork for EthSync {
 }
 
 /// IP fiter
-#[derive(Binary, Clone, Debug, PartialEq, Eq)]
+#[derive(Clone, Debug, PartialEq, Eq)]
+#[cfg_attr(feature = "ipc", derive(Binary))]
 pub enum AllowIP {
 	/// Connect to any address
 	All,
@@ -337,7 +434,8 @@ impl AllowIP {
 	}
 }
 
-#[derive(Binary, Debug, Clone, PartialEq, Eq)]
+#[derive(Debug, Clone, PartialEq, Eq)]
+#[cfg_attr(feature = "ipc", derive(Binary))]
 /// Network service configuration
 pub struct NetworkConfiguration {
 	/// Directory path to store general network configuration. None means nothing will be saved
@@ -375,26 +473,18 @@ pub struct NetworkConfiguration {
 }
 
 impl NetworkConfiguration {
+	/// Create a new default config.
 	pub fn new() -> Self {
 		From::from(BasicNetworkConfiguration::new())
 	}
 
+	/// Create a new local config.
 	pub fn new_local() -> Self {
 		From::from(BasicNetworkConfiguration::new_local())
 	}
 
-	fn validate(&self) -> Result<(), AddrParseError> {
-		if let Some(ref addr) = self.listen_address {
-			try!(SocketAddr::from_str(&addr));
-		}
-		if let Some(ref addr) = self.public_address {
-			try!(SocketAddr::from_str(&addr));
-		}
-		Ok(())
-	}
-
+	/// Attempt to convert this config into a BasicNetworkConfiguration.
 	pub fn into_basic(self) -> Result<BasicNetworkConfiguration, AddrParseError> {
-
 		Ok(BasicNetworkConfiguration {
 			config_path: self.config_path,
 			net_config_path: self.net_config_path,
@@ -447,9 +537,14 @@ impl From<BasicNetworkConfiguration> for NetworkConfiguration {
 	}
 }
 
-#[derive(Debug, Binary, Clone)]
+/// Configuration for IPC service.
+#[derive(Debug, Clone)]
+#[cfg_attr(feature = "ipc", derive(Binary))]
 pub struct ServiceConfiguration {
+	/// Sync config.
 	pub sync: SyncConfig,
+	/// Network configuration.
 	pub net: NetworkConfiguration,
+	/// IPC path.
 	pub io_path: String,
 }

sync/src/lib.rs

@@ -37,6 +37,8 @@ extern crate semver;
 extern crate parking_lot;
 extern crate rlp;
 
+extern crate ethcore_light as light;
+
 #[cfg(test)] extern crate ethcore_devtools as devtools;
 #[cfg(test)] extern crate ethkey;
 
@@ -59,12 +61,16 @@ mod transactions_stats;
 #[cfg(test)]
 mod tests;
 
+#[cfg(feature = "ipc")]
 mod api {
 	#![allow(dead_code, unused_assignments, unused_variables, missing_docs)] // codegen issues
 	include!(concat!(env!("OUT_DIR"), "/api.rs"));
 }
 
-pub use api::{EthSync, SyncProvider, SyncClient, NetworkManagerClient, ManageNetwork, SyncConfig,
+#[cfg(not(feature = "ipc"))]
+mod api;
+
+pub use api::{EthSync, Params, SyncProvider, ManageNetwork, SyncConfig,
 	ServiceConfiguration, NetworkConfiguration, PeerInfo, AllowIP, TransactionStats};
 pub use chain::{SyncStatus, SyncState};
 pub use network::{is_valid_node_url, NonReservedPeerMode, NetworkError};

sync/src/tests/mod.rs

@@ -18,4 +18,6 @@ pub mod helpers;
 pub mod snapshot;
 mod chain;
 mod consensus;
+
+#[cfg(feature = "ipc")]
 mod rpc;