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openethereum/util/src/network/discovery.rs

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// 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/>.
use bytes::Bytes;
use std::net::SocketAddr;
use std::collections::{HashSet, HashMap, BTreeMap, VecDeque};
use std::mem;
use std::cmp;
use mio::*;
use mio::udp::*;
use sha3::*;
use time;
use hash::*;
use crypto::*;
use rlp::*;
use network::node_table::*;
use network::error::NetworkError;
use io::StreamToken;
use network::PROTOCOL_VERSION;
const ADDRESS_BYTES_SIZE: u32 = 32; // Size of address type in bytes.
const ADDRESS_BITS: u32 = 8 * ADDRESS_BYTES_SIZE; // Denoted by n in [Kademlia].
const NODE_BINS: u32 = ADDRESS_BITS - 1; // Size of m_state (excludes root, which is us).
const DISCOVERY_MAX_STEPS: u16 = 8; // Max iterations of discovery. (discover)
const BUCKET_SIZE: usize = 16; // Denoted by k in [Kademlia]. Number of nodes stored in each bucket.
const ALPHA: usize = 3; // Denoted by \alpha in [Kademlia]. Number of concurrent FindNode requests.
const MAX_DATAGRAM_SIZE: usize = 1280;
const PACKET_PING: u8 = 1;
const PACKET_PONG: u8 = 2;
const PACKET_FIND_NODE: u8 = 3;
const PACKET_NEIGHBOURS: u8 = 4;
const PING_TIMEOUT_MS: u64 = 300;
#[derive(Clone, Debug)]
pub struct NodeEntry {
pub id: NodeId,
pub endpoint: NodeEndpoint,
}
pub struct BucketEntry {
pub address: NodeEntry,
pub timeout: Option<u64>,
}
struct NodeBucket {
nodes: VecDeque<BucketEntry>, //sorted by last active
}
impl NodeBucket {
fn new() -> NodeBucket {
NodeBucket {
nodes: VecDeque::new()
}
}
}
struct Datagramm {
payload: Bytes,
address: SocketAddr,
}
pub struct Discovery {
id: NodeId,
secret: Secret,
public_endpoint: NodeEndpoint,
udp_socket: UdpSocket,
token: StreamToken,
discovery_round: u16,
discovery_id: NodeId,
discovery_nodes: HashSet<NodeId>,
node_buckets: Vec<NodeBucket>,
send_queue: VecDeque<Datagramm>
}
pub struct TableUpdates {
pub added: HashMap<NodeId, NodeEntry>,
pub removed: HashSet<NodeId>,
}
impl Discovery {
pub fn new(key: &KeyPair, listen: SocketAddr, public: NodeEndpoint, token: StreamToken) -> Discovery {
let socket = UdpSocket::bound(&listen).expect("Error binding UDP socket");
Discovery {
id: key.public().clone(),
secret: key.secret().clone(),
public_endpoint: public,
token: token,
discovery_round: 0,
discovery_id: NodeId::new(),
discovery_nodes: HashSet::new(),
node_buckets: (0..NODE_BINS).map(|_| NodeBucket::new()).collect(),
udp_socket: socket,
send_queue: VecDeque::new(),
}
}
/// Add a new node to discovery table. Pings the node.
pub fn add_node(&mut self, e: NodeEntry) {
let endpoint = e.endpoint.clone();
self.update_node(e);
self.ping(&endpoint);
}
/// Add a list of known nodes to the table.
pub fn init_node_list(&mut self, mut nodes: Vec<NodeEntry>) {
for n in nodes.drain(..) {
self.update_node(n);
}
}
fn update_node(&mut self, e: NodeEntry) {
trace!(target: "discovery", "Inserting {:?}", &e);
let ping = {
let mut bucket = self.node_buckets.get_mut(Discovery::distance(&self.id, &e.id) as usize).unwrap();
let updated = if let Some(node) = bucket.nodes.iter_mut().find(|n| n.address.id == e.id) {
node.address = e.clone();
node.timeout = None;
true
} else { false };
if !updated {
bucket.nodes.push_front(BucketEntry { address: e, timeout: None });
}
if bucket.nodes.len() > BUCKET_SIZE {
//ping least active node
bucket.nodes.back_mut().unwrap().timeout = Some(time::precise_time_ns());
Some(bucket.nodes.back().unwrap().address.endpoint.clone())
} else { None }
};
if let Some(endpoint) = ping {
self.ping(&endpoint);
}
}
fn start(&mut self) {
trace!(target: "discovery", "Starting discovery");
self.discovery_round = 0;
self.discovery_id.randomize(); //TODO: use cryptographic nonce
self.discovery_nodes.clear();
}
fn discover(&mut self) {
if self.discovery_round == DISCOVERY_MAX_STEPS {
return;
}
trace!(target: "discovery", "Starting round {:?}", self.discovery_round);
let mut tried_count = 0;
{
let nearest = Discovery::nearest_node_entries(&self.discovery_id, &self.node_buckets).into_iter();
let nearest = nearest.filter(|x| !self.discovery_nodes.contains(&x.id)).take(ALPHA).collect::<Vec<_>>();
for r in nearest {
let rlp = encode(&(&[self.discovery_id.clone()][..]));
self.send_packet(PACKET_FIND_NODE, &r.endpoint.udp_address(), &rlp);
self.discovery_nodes.insert(r.id.clone());
tried_count += 1;
trace!(target: "discovery", "Sent FindNode to {:?}", &r.endpoint);
}
}
if tried_count == 0 {
trace!(target: "discovery", "Completing discovery");
self.discovery_round = DISCOVERY_MAX_STEPS;
self.discovery_nodes.clear();
return;
}
self.discovery_round += 1;
}
fn distance(a: &NodeId, b: &NodeId) -> u32 {
let d = a.sha3() ^ b.sha3();
let mut ret:u32 = 0;
for i in 0..32 {
let mut v: u8 = d[i];
while v != 0 {
v >>= 1;
ret += 1;
}
}
ret
}
fn ping(&mut self, node: &NodeEndpoint) {
let mut rlp = RlpStream::new_list(3);
rlp.append(&PROTOCOL_VERSION);
self.public_endpoint.to_rlp_list(&mut rlp);
node.to_rlp_list(&mut rlp);
trace!(target: "discovery", "Sent Ping to {:?}", &node);
self.send_packet(PACKET_PING, &node.udp_address(), &rlp.drain());
}
fn send_packet(&mut self, packet_id: u8, address: &SocketAddr, payload: &[u8]) {
let mut rlp = RlpStream::new();
rlp.append_raw(&[packet_id], 1);
let source = Rlp::new(payload);
rlp.begin_list(source.item_count() + 1);
for i in 0 .. source.item_count() {
rlp.append_raw(source.at(i).as_raw(), 1);
}
let timestamp = time::get_time().sec as u32 + 60;
rlp.append(&timestamp);
let bytes = rlp.drain();
let hash = bytes.as_ref().sha3();
let signature = match ec::sign(&self.secret, &hash) {
Ok(s) => s,
Err(_) => {
warn!("Error signing UDP packet");
return;
}
};
let mut packet = Bytes::with_capacity(bytes.len() + 32 + 65);
packet.extend(hash.iter());
packet.extend(signature.iter());
packet.extend(bytes.iter());
let signed_hash = (&packet[32..]).sha3();
packet[0..32].clone_from_slice(&signed_hash);
self.send_to(packet, address.clone());
}
#[allow(map_clone)]
fn nearest_node_entries(target: &NodeId, buckets: &[NodeBucket]) -> Vec<NodeEntry> {
let mut found: BTreeMap<u32, Vec<&NodeEntry>> = BTreeMap::new();
let mut count = 0;
// Sort nodes by distance to target
for bucket in buckets {
for node in &bucket.nodes {
let distance = Discovery::distance(target, &node.address.id);
found.entry(distance).or_insert_with(Vec::new).push(&node.address);
if count == BUCKET_SIZE {
// delete the most distant element
let remove = {
let (_, last) = found.iter_mut().next_back().unwrap();
last.pop();
last.is_empty()
};
if remove {
found.remove(&distance);
}
}
else {
count += 1;
}
}
}
let mut ret:Vec<NodeEntry> = Vec::new();
for nodes in found.values() {
ret.extend(nodes.iter().map(|&n| n.clone()));
}
ret
}
pub fn writable(&mut self) {
if self.send_queue.is_empty() {
return;
}
while !self.send_queue.is_empty() {
let data = self.send_queue.pop_front().unwrap();
match self.udp_socket.send_to(&data.payload, &data.address) {
Ok(Some(size)) if size == data.payload.len() => {
},
Ok(Some(_)) => {
warn!("UDP sent incomplete datagramm");
},
Ok(None) => {
self.send_queue.push_front(data);
return;
}
Err(e) => {
warn!("UDP send error: {:?}, address: {:?}", e, &data.address);
return;
}
}
}
}
fn send_to(&mut self, payload: Bytes, address: SocketAddr) {
self.send_queue.push_back(Datagramm { payload: payload, address: address });
}
pub fn readable(&mut self) -> Option<TableUpdates> {
let mut buf: [u8; MAX_DATAGRAM_SIZE] = unsafe { mem::uninitialized() };
match self.udp_socket.recv_from(&mut buf) {
Ok(Some((len, address))) => self.on_packet(&buf[0..len], address).unwrap_or_else(|e| {
debug!("Error processing UDP packet: {:?}", e);
None
}),
Ok(_) => None,
Err(e) => {
warn!("Error reading UPD socket: {:?}", e);
None
}
}
}
fn on_packet(&mut self, packet: &[u8], from: SocketAddr) -> Result<Option<TableUpdates>, NetworkError> {
// validate packet
if packet.len() < 32 + 65 + 4 + 1 {
return Err(NetworkError::BadProtocol);
}
let hash_signed = (&packet[32..]).sha3();
if hash_signed[..] != packet[0..32] {
return Err(NetworkError::BadProtocol);
}
let signed = &packet[(32 + 65)..];
let signature = Signature::from_slice(&packet[32..(32 + 65)]);
let node_id = try!(ec::recover(&signature, &signed.sha3()));
let packet_id = signed[0];
let rlp = UntrustedRlp::new(&signed[1..]);
match packet_id {
PACKET_PING => self.on_ping(&rlp, &node_id, &from),
PACKET_PONG => self.on_pong(&rlp, &node_id, &from),
PACKET_FIND_NODE => self.on_find_node(&rlp, &node_id, &from),
PACKET_NEIGHBOURS => self.on_neighbours(&rlp, &node_id, &from),
_ => {
debug!("Unknown UDP packet: {}", packet_id);
Ok(None)
}
}
}
fn on_ping(&mut self, rlp: &UntrustedRlp, node: &NodeId, from: &SocketAddr) -> Result<Option<TableUpdates>, NetworkError> {
trace!(target: "discovery", "Got Ping from {:?}", &from);
let version: u32 = try!(rlp.val_at(0));
if version != PROTOCOL_VERSION {
debug!(target: "discovery", "Unexpected protocol version: {}", version);
return Err(NetworkError::BadProtocol);
}
let source = try!(NodeEndpoint::from_rlp(&try!(rlp.at(1))));
let dest = try!(NodeEndpoint::from_rlp(&try!(rlp.at(2))));
let timestamp: u64 = try!(rlp.val_at(3));
if timestamp < time::get_time().sec as u64{
debug!(target: "discovery", "Expired ping");
return Err(NetworkError::Expired);
}
let mut entry = NodeEntry { id: node.clone(), endpoint: source.clone() };
if !entry.endpoint.is_valid() {
debug!(target: "discovery", "Got bad address: {:?}, using {:?} instead", entry, from);
entry.endpoint.address = from.clone();
}
if !entry.endpoint.is_global() {
debug!(target: "discovery", "Got local address: {:?}, using {:?} instead", entry, from);
entry.endpoint.address = from.clone();
}
self.update_node(entry.clone());
let hash = rlp.as_raw().sha3();
let mut response = RlpStream::new_list(2);
dest.to_rlp_list(&mut response);
response.append(&hash);
self.send_packet(PACKET_PONG, &entry.endpoint.udp_address(), &response.drain());
let mut added_map = HashMap::new();
added_map.insert(node.clone(), entry);
Ok(Some(TableUpdates { added: added_map, removed: HashSet::new() }))
}
fn on_pong(&mut self, rlp: &UntrustedRlp, node: &NodeId, from: &SocketAddr) -> Result<Option<TableUpdates>, NetworkError> {
trace!(target: "discovery", "Got Pong from {:?}", &from);
// TODO: validate pong packet
let dest = try!(NodeEndpoint::from_rlp(&try!(rlp.at(0))));
let timestamp: u64 = try!(rlp.val_at(2));
if timestamp < time::get_time().sec as u64 {
return Err(NetworkError::Expired);
}
let mut entry = NodeEntry { id: node.clone(), endpoint: dest };
if !entry.endpoint.is_valid() {
debug!(target: "discovery", "Bad address: {:?}", entry);
entry.endpoint.address = from.clone();
}
self.update_node(entry.clone());
let mut added_map = HashMap::new();
added_map.insert(node.clone(), entry);
Ok(Some(TableUpdates { added: added_map, removed: HashSet::new() }))
}
fn on_find_node(&mut self, rlp: &UntrustedRlp, _node: &NodeId, from: &SocketAddr) -> Result<Option<TableUpdates>, NetworkError> {
trace!(target: "discovery", "Got FindNode from {:?}", &from);
let target: NodeId = try!(rlp.val_at(0));
let timestamp: u64 = try!(rlp.val_at(1));
if timestamp < time::get_time().sec as u64 {
return Err(NetworkError::Expired);
}
let limit = (MAX_DATAGRAM_SIZE - 109) / 90;
let nearest = Discovery::nearest_node_entries(&target, &self.node_buckets);
if nearest.is_empty() {
return Ok(None);
}
let mut rlp = RlpStream::new_list(1);
rlp.begin_list(cmp::min(limit, nearest.len()));
for n in 0 .. nearest.len() {
rlp.begin_list(4);
nearest[n].endpoint.to_rlp(&mut rlp);
rlp.append(&nearest[n].id);
if (n + 1) % limit == 0 || n == nearest.len() - 1 {
self.send_packet(PACKET_NEIGHBOURS, &from, &rlp.drain());
trace!(target: "discovery", "Sent {} Neighbours to {:?}", n, &from);
rlp = RlpStream::new_list(1);
rlp.begin_list(cmp::min(limit, nearest.len() - n));
}
}
Ok(None)
}
fn on_neighbours(&mut self, rlp: &UntrustedRlp, _node: &NodeId, from: &SocketAddr) -> Result<Option<TableUpdates>, NetworkError> {
// TODO: validate packet
let mut added = HashMap::new();
trace!(target: "discovery", "Got {} Neighbours from {:?}", try!(rlp.at(0)).item_count(), &from);
for r in try!(rlp.at(0)).iter() {
let endpoint = try!(NodeEndpoint::from_rlp(&r));
if !endpoint.is_valid() {
debug!(target: "discovery", "Bad address: {:?}", endpoint);
continue;
}
let node_id: NodeId = try!(r.val_at(3));
if node_id == self.id {
continue;
}
let entry = NodeEntry { id: node_id.clone(), endpoint: endpoint };
added.insert(node_id, entry.clone());
self.ping(&entry.endpoint);
self.update_node(entry);
}
Ok(Some(TableUpdates { added: added, removed: HashSet::new() }))
}
fn check_expired(&mut self) -> HashSet<NodeId> {
let now = time::precise_time_ns();
let mut removed: HashSet<NodeId> = HashSet::new();
for bucket in &mut self.node_buckets {
bucket.nodes.retain(|node| {
if let Some(timeout) = node.timeout {
if now - timeout < PING_TIMEOUT_MS * 1000_0000 {
true
}
else {
trace!(target: "discovery", "Removed expired node {:?}", &node.address);
removed.insert(node.address.id.clone());
false
}
} else { true }
});
}
removed
}
pub fn round(&mut self) -> Option<TableUpdates> {
let removed = self.check_expired();
self.discover();
if !removed.is_empty() {
Some(TableUpdates { added: HashMap::new(), removed: removed })
} else { None }
}
pub fn refresh(&mut self) {
self.start();
}
pub fn register_socket<Host:Handler>(&self, event_loop: &mut EventLoop<Host>) -> Result<(), NetworkError> {
event_loop.register(&self.udp_socket, Token(self.token), EventSet::all(), PollOpt::edge()).expect("Error registering UDP socket");
Ok(())
}
pub fn update_registration<Host:Handler>(&self, event_loop: &mut EventLoop<Host>) -> Result<(), NetworkError> {
let mut registration = EventSet::readable();
if !self.send_queue.is_empty() {
registration = registration | EventSet::writable();
}
event_loop.reregister(&self.udp_socket, Token(self.token), registration, PollOpt::edge()).expect("Error reregistering UDP socket");
Ok(())
}
}
#[cfg(test)]
mod tests {
use super::*;
use hash::*;
use std::net::*;
use network::node_table::*;
use crypto::KeyPair;
use std::str::FromStr;
#[test]
fn discovery() {
let key1 = KeyPair::create().unwrap();
let key2 = KeyPair::create().unwrap();
let ep1 = NodeEndpoint { address: SocketAddr::from_str("127.0.0.1:40444").unwrap(), udp_port: 40444 };
let ep2 = NodeEndpoint { address: SocketAddr::from_str("127.0.0.1:40445").unwrap(), udp_port: 40445 };
let mut discovery1 = Discovery::new(&key1, ep1.address.clone(), ep1.clone(), 0);
let mut discovery2 = Discovery::new(&key2, ep2.address.clone(), ep2.clone(), 0);
let node1 = Node::from_str("enode://a979fb575495b8d6db44f750317d0f4622bf4c2aa3365d6af7c284339968eef29b69ad0dce72a4d8db5ebb4968de0e3bec910127f134779fbcb0cb6d3331163c@127.0.0.1:7770").unwrap();
let node2 = Node::from_str("enode://b979fb575495b8d6db44f750317d0f4622bf4c2aa3365d6af7c284339968eef29b69ad0dce72a4d8db5ebb4968de0e3bec910127f134779fbcb0cb6d3331163c@127.0.0.1:7771").unwrap();
discovery1.add_node(NodeEntry { id: node1.id.clone(), endpoint: node1. endpoint.clone() });
discovery1.add_node(NodeEntry { id: node2.id.clone(), endpoint: node2. endpoint.clone() });
discovery2.add_node(NodeEntry { id: key1.public().clone(), endpoint: ep1.clone() });
discovery2.refresh();
for _ in 0 .. 10 {
while !discovery1.send_queue.is_empty() {
let datagramm = discovery1.send_queue.pop_front().unwrap();
if datagramm.address == ep2.address {
discovery2.on_packet(&datagramm.payload, ep1.address.clone()).ok();
}
}
while !discovery2.send_queue.is_empty() {
let datagramm = discovery2.send_queue.pop_front().unwrap();
if datagramm.address == ep1.address {
discovery1.on_packet(&datagramm.payload, ep2.address.clone()).ok();
}
}
discovery2.round();
}
assert_eq!(Discovery::nearest_node_entries(&NodeId::new(), &discovery2.node_buckets).len(), 3)
}
}
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