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Don't poll network unnecessarily. (#1977)

Browse Source 
* Don't poll network unnecessarily.

* Fix ci.

* Damn tokio.

* Address review comments.

* Update deps.

* Don't drop packet if socket is not writable.

* Increase TTL and rename to `query_interval`.

* Update CHANGELOG.

Co-authored-by: Roman S. Borschel <roman@parity.io>
This commit is contained in:
David Craven
2021-03-02 10:18:24 +01:00
committed by GitHub
parent 6b5fa0324d
commit b727efee13
11 changed files with 651 additions and 950 deletions
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2
examples/chat-tokio.rs
View File

@ -120,7 +120,7 @@ async fn main() -> Result<(), Box<dyn Error>> {
// Create a Swarm to manage peers and events. // Create a Swarm to manage peers and events.
let mut swarm = { let mut swarm = {
let mdns = Mdns::new().await?; let mdns = Mdns::new(Default::default()).await?;
let mut behaviour = MyBehaviour { let mut behaviour = MyBehaviour {
floodsub: Floodsub::new(peer_id.clone()), floodsub: Floodsub::new(peer_id.clone()),
mdns, mdns,

4
examples/chat.rs
View File

@ -58,7 +58,7 @@ use libp2p::{
NetworkBehaviour, NetworkBehaviour,
identity, identity,
floodsub::{self, Floodsub, FloodsubEvent}, floodsub::{self, Floodsub, FloodsubEvent},
mdns::{Mdns, MdnsEvent}, mdns::{Mdns, MdnsConfig, MdnsEvent},
swarm::NetworkBehaviourEventProcess swarm::NetworkBehaviourEventProcess
}; };
use std::{error::Error, task::{Context, Poll}}; use std::{error::Error, task::{Context, Poll}};
@ -121,7 +121,7 @@ fn main() -> Result<(), Box<dyn Error>> {
// Create a Swarm to manage peers and events // Create a Swarm to manage peers and events
let mut swarm = { let mut swarm = {
let mdns = task::block_on(Mdns::new())?; let mdns = task::block_on(Mdns::new(MdnsConfig::default()))?;
let mut behaviour = MyBehaviour { let mut behaviour = MyBehaviour {
floodsub: Floodsub::new(local_peer_id.clone()), floodsub: Floodsub::new(local_peer_id.clone()),
mdns, mdns,

4
examples/distributed-key-value-store.rs
View File

@ -60,7 +60,7 @@ use libp2p::{
Swarm, Swarm,
build_development_transport, build_development_transport,
identity, identity,
mdns::{Mdns, MdnsEvent}, mdns::{Mdns, MdnsConfig, MdnsEvent},
swarm::NetworkBehaviourEventProcess swarm::NetworkBehaviourEventProcess
}; };
use std::{error::Error, task::{Context, Poll}}; use std::{error::Error, task::{Context, Poll}};
@ -151,7 +151,7 @@ fn main() -> Result<(), Box<dyn Error>> {
// Create a Kademlia behaviour. // Create a Kademlia behaviour.
let store = MemoryStore::new(local_peer_id.clone()); let store = MemoryStore::new(local_peer_id.clone());
let kademlia = Kademlia::new(local_peer_id.clone(), store); let kademlia = Kademlia::new(local_peer_id.clone(), store);
let mdns = task::block_on(Mdns::new())?; let mdns = task::block_on(Mdns::new(MdnsConfig::default()))?;
let behaviour = MyBehaviour { kademlia, mdns }; let behaviour = MyBehaviour { kademlia, mdns };
Swarm::new(transport, behaviour, local_peer_id) Swarm::new(transport, behaviour, local_peer_id)
}; };

61
examples/mdns-passive-discovery.rs
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@ -18,43 +18,42 @@
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER // FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE. // DEALINGS IN THE SOFTWARE.
use async_std::task; use libp2p::{identity, mdns::{Mdns, MdnsConfig, MdnsEvent}, PeerId, Swarm};
use libp2p::mdns::service::{MdnsPacket, MdnsService};
use std::error::Error; use std::error::Error;
fn main() -> Result<(), Box<dyn Error>> { #[async_std::main]
// This example provides passive discovery of the libp2p nodes on the async fn main() -> Result<(), Box<dyn Error>> {
// network that send mDNS queries and answers. env_logger::init();
task::block_on(async move {
let mut service = MdnsService::new().await?; // Create a random PeerId.
let id_keys = identity::Keypair::generate_ed25519();
let peer_id = PeerId::from(id_keys.public());
println!("Local peer id: {:?}", peer_id);
// Create a transport.
let transport = libp2p::build_development_transport(id_keys)?;
// Create an MDNS network behaviour.
let behaviour = Mdns::new(MdnsConfig::default()).await?;
// Create a Swarm that establishes connections through the given transport.
// Note that the MDNS behaviour itself will not actually inititiate any connections,
// as it only uses UDP.
let mut swarm = Swarm::new(transport, behaviour, peer_id);
Swarm::listen_on(&mut swarm, "/ip4/0.0.0.0/tcp/0".parse()?)?;
loop { loop {
let (srv, packet) = service.next().await; match swarm.next().await {
match packet { MdnsEvent::Discovered(peers) => {
MdnsPacket::Query(query) => { for (peer, addr) in peers {
// We detected a libp2p mDNS query on the network. In a real application, you println!("discovered {} {}", peer, addr);
// probably want to answer this query by doing `query.respond(...)`.
println!("Detected query from {:?}", query.remote_addr());
} }
MdnsPacket::Response(response) => { }
// We detected a libp2p mDNS response on the network. Responses are for MdnsEvent::Expired(expired) => {
// everyone and not just for the requester, which makes it possible to for (peer, addr) in expired {
// passively listen. println!("expired {} {}", peer, addr);
for peer in response.discovered_peers() {
println!("Discovered peer {:?}", peer.id());
// These are the self-reported addresses of the peer we just discovered.
for addr in peer.addresses() {
println!(" Address = {:?}", addr);
} }
} }
} }
MdnsPacket::ServiceDiscovery(query) => {
// The last possibility is a service detection query from DNS-SD.
// Just like `Query`, in a real application you probably want to call
// `query.respond`.
println!("Detected service query from {:?}", query.remote_addr());
} }
} }
service = srv
}
})
}

13
protocols/mdns/CHANGELOG.md
View File

@ -1,5 +1,18 @@
# 0.29.0 [unreleased] # 0.29.0 [unreleased]
- Introduce `MdnsConfig` with configurable TTL of discovered peer
records and configurable multicast query interval. The default
query interval is increased from 20 seconds to 5 minutes, to
significantly reduce bandwidth usage. To ensure timely peer
discovery in the majority of cases, a multicast query is
initiated whenever a change on a network interface is detected,
which includes MDNS initialisation at node startup. If necessary
the MDNS query interval can be reduced via the `MdnsConfig`.
The `MdnsService` has been removed from the public API, making
it compulsory that all uses occur through the `Mdns` `NetworkBehaviour`.
An `MdnsConfig` must now be given to `Mdns::new()`.
[PR 1977](https://github.com/libp2p/rust-libp2p/pull/1977).
- Update `libp2p-swarm`. - Update `libp2p-swarm`.
# 0.28.1 [2021-02-15] # 0.28.1 [2021-02-15]

20
protocols/mdns/Cargo.toml
View File

@ -10,21 +10,21 @@ keywords = ["peer-to-peer", "libp2p", "networking"]
categories = ["network-programming", "asynchronous"] categories = ["network-programming", "asynchronous"]
[dependencies] [dependencies]
async-io = "1.3.0" async-io = "1.3.1"
data-encoding = "2.3.1" data-encoding = "2.3.2"
dns-parser = "0.8.0" dns-parser = "0.8.0"
futures = "0.3.8" futures = "0.3.13"
if-watch = "0.1.8" if-watch = "0.2.0"
lazy_static = "1.4.0" lazy_static = "1.4.0"
libp2p-core = { version = "0.27.0", path = "../../core" } libp2p-core = { version = "0.27.0", path = "../../core" }
libp2p-swarm = { version = "0.28.0", path = "../../swarm" } libp2p-swarm = { version = "0.28.0", path = "../../swarm" }
log = "0.4.11" log = "0.4.14"
rand = "0.7.3" rand = "0.8.3"
smallvec = "1.5.0" smallvec = "1.6.1"
socket2 = { version = "0.3.17", features = ["reuseport"] } socket2 = { version = "0.3.19", features = ["reuseport"] }
void = "1.0.2" void = "1.0.2"
[dev-dependencies] [dev-dependencies]
async-std = "1.7.0" async-std = "1.9.0"
if-addrs = "0.6.5" if-addrs = "0.6.5"
tokio = { version = "1.0.1", default-features = false, features = ["rt", "rt-multi-thread"] } tokio = { version = "1.2.0", default-features = false, features = ["rt", "rt-multi-thread"] }

434
protocols/mdns/src/behaviour.rs
View File

@ -18,33 +18,80 @@
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER // FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE. // DEALINGS IN THE SOFTWARE.
use crate::service::{MdnsPacket, MdnsService, build_query_response, build_service_discovery_response}; use crate::dns::{build_query, build_query_response, build_service_discovery_response};
use async_io::Timer; use crate::query::MdnsPacket;
use async_io::{Async, Timer};
use futures::prelude::*; use futures::prelude::*;
use if_watch::{IfEvent, IfWatcher};
use lazy_static::lazy_static;
use libp2p_core::{ use libp2p_core::{
Multiaddr, address_translation, connection::ConnectionId, multiaddr::Protocol, Multiaddr, PeerId,
PeerId,
address_translation,
connection::ConnectionId,
multiaddr::Protocol
}; };
use libp2p_swarm::{ use libp2p_swarm::{
NetworkBehaviour, protocols_handler::DummyProtocolsHandler, NetworkBehaviour, NetworkBehaviourAction,
NetworkBehaviourAction, PollParameters, ProtocolsHandler,
PollParameters,
ProtocolsHandler,
protocols_handler::DummyProtocolsHandler
}; };
use smallvec::SmallVec; use smallvec::SmallVec;
use std::{cmp, fmt, io, iter, mem, pin::Pin, time::{Duration, Instant}, task::Context, task::Poll}; use socket2::{Domain, Socket, Type};
use std::{
cmp,
collections::VecDeque,
fmt, io, iter,
net::{IpAddr, Ipv4Addr, SocketAddr, UdpSocket},
pin::Pin,
task::Context,
task::Poll,
time::{Duration, Instant},
};
const MDNS_RESPONSE_TTL: std::time::Duration = Duration::from_secs(5 * 60); lazy_static! {
static ref IPV4_MDNS_MULTICAST_ADDRESS: SocketAddr =
SocketAddr::from((Ipv4Addr::new(224, 0, 0, 251), 5353));
}
pub struct MdnsConfig {
/// TTL to use for mdns records.
pub ttl: Duration,
/// Interval at which to poll the network for new peers. This isn't
/// necessary during normal operation but avoids the case that an
/// initial packet was lost and not discovering any peers until a new
/// peer joins the network. Receiving an mdns packet resets the timer
/// preventing unnecessary traffic.
pub query_interval: Duration,
}
impl Default for MdnsConfig {
fn default() -> Self {
Self {
ttl: Duration::from_secs(6 * 60),
query_interval: Duration::from_secs(5 * 60),
}
}
}
/// A `NetworkBehaviour` for mDNS. Automatically discovers peers on the local network and adds /// A `NetworkBehaviour` for mDNS. Automatically discovers peers on the local network and adds
/// them to the topology. /// them to the topology.
#[derive(Debug)]
pub struct Mdns { pub struct Mdns {
/// The inner service. /// Main socket for listening.
service: MdnsBusyWrapper, recv_socket: Async<UdpSocket>,
/// Query socket for making queries.
send_socket: Async<UdpSocket>,
/// Iface watcher.
if_watch: IfWatcher,
/// Buffer used for receiving data from the main socket.
/// RFC6762 discourages packets larger than the interface MTU, but allows sizes of up to 9000
/// bytes, if it can be ensured that all participating devices can handle such large packets.
/// For computers with several interfaces and IP addresses responses can easily reach sizes in
/// the range of 3000 bytes, so 4096 seems sensible for now. For more information see
/// [rfc6762](https://tools.ietf.org/html/rfc6762#page-46).
recv_buffer: [u8; 4096],
/// Buffers pending to send on the main socket.
send_buffer: VecDeque<Vec<u8>>,
/// List of nodes that we have discovered, the address, and when their TTL expires. /// List of nodes that we have discovered, the address, and when their TTL expires.
/// ///
@ -56,45 +103,55 @@ pub struct Mdns {
/// ///
/// `None` if `discovered_nodes` is empty. /// `None` if `discovered_nodes` is empty.
closest_expiration: Option<Timer>, closest_expiration: Option<Timer>,
}
/// `MdnsService::next` takes ownership of `self`, returning a future that resolves with both itself /// Queued events.
/// and a `MdnsPacket` (similar to the old Tokio socket send style). The two states are thus `Free` events: VecDeque<MdnsEvent>,
/// with an `MdnsService` or `Busy` with a future returning the original `MdnsService` and an
/// `MdnsPacket`.
enum MdnsBusyWrapper {
Free(MdnsService),
Busy(Pin<Box<dyn Future<Output = (MdnsService, MdnsPacket)> + Send>>),
Poisoned,
}
impl fmt::Debug for MdnsBusyWrapper { /// Discovery interval.
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { query_interval: Duration,
match self {
Self::Free(service) => { /// Record ttl.
fmt.debug_struct("MdnsBusyWrapper::Free") ttl: Duration,
.field("service", service)
.finish() /// Discovery timer.
}, timeout: Timer,
Self::Busy(_) => {
fmt.debug_struct("MdnsBusyWrapper::Busy")
.finish()
}
Self::Poisoned => {
fmt.debug_struct("MdnsBusyWrapper::Poisoned")
.finish()
}
}
}
} }
impl Mdns { impl Mdns {
/// Builds a new `Mdns` behaviour. /// Builds a new `Mdns` behaviour.
pub async fn new() -> io::Result<Self> { pub async fn new(config: MdnsConfig) -> io::Result<Self> {
let recv_socket = {
let socket = Socket::new(
Domain::ipv4(),
Type::dgram(),
Some(socket2::Protocol::udp()),
)?;
socket.set_reuse_address(true)?;
#[cfg(unix)]
socket.set_reuse_port(true)?;
socket.bind(&SocketAddr::new(Ipv4Addr::UNSPECIFIED.into(), 5353).into())?;
let socket = socket.into_udp_socket();
socket.set_multicast_loop_v4(true)?;
socket.set_multicast_ttl_v4(255)?;
Async::new(socket)?
};
let send_socket = {
let socket = UdpSocket::bind((Ipv4Addr::UNSPECIFIED, 0))?;
Async::new(socket)?
};
let if_watch = if_watch::IfWatcher::new().await?;
Ok(Self { Ok(Self {
service: MdnsBusyWrapper::Free(MdnsService::new().await?), recv_socket,
send_socket,
if_watch,
recv_buffer: [0; 4096],
send_buffer: Default::default(),
discovered_nodes: SmallVec::new(), discovered_nodes: SmallVec::new(),
closest_expiration: None, closest_expiration: None,
events: Default::default(),
query_interval: config.query_interval,
ttl: config.ttl,
timeout: Timer::interval(config.query_interval),
}) })
} }
@ -107,6 +164,77 @@ impl Mdns {
pub fn discovered_nodes(&self) -> impl ExactSizeIterator<Item = &PeerId> { pub fn discovered_nodes(&self) -> impl ExactSizeIterator<Item = &PeerId> {
self.discovered_nodes.iter().map(|(p, _, _)| p) self.discovered_nodes.iter().map(|(p, _, _)| p)
} }
fn inject_mdns_packet(&mut self, packet: MdnsPacket, params: &impl PollParameters) {
self.timeout.set_interval(self.query_interval);
match packet {
MdnsPacket::Query(query) => {
for packet in build_query_response(
query.query_id(),
*params.local_peer_id(),
params.listened_addresses(),
self.ttl,
) {
self.send_buffer.push_back(packet);
}
}
MdnsPacket::Response(response) => {
// We replace the IP address with the address we observe the
// remote as and the address they listen on.
let obs_ip = Protocol::from(response.remote_addr().ip());
let obs_port = Protocol::Udp(response.remote_addr().port());
let observed: Multiaddr = iter::once(obs_ip).chain(iter::once(obs_port)).collect();
let mut discovered: SmallVec<[_; 4]> = SmallVec::new();
for peer in response.discovered_peers() {
if peer.id() == params.local_peer_id() {
continue;
}
let new_expiration = Instant::now() + peer.ttl();
let mut addrs: Vec<Multiaddr> = Vec::new();
for addr in peer.addresses() {
if let Some(new_addr) = address_translation(&addr, &observed) {
addrs.push(new_addr.clone())
}
addrs.push(addr.clone())
}
for addr in addrs {
if let Some((_, _, cur_expires)) = self
.discovered_nodes
.iter_mut()
.find(|(p, a, _)| p == peer.id() && *a == addr)
{
*cur_expires = cmp::max(*cur_expires, new_expiration);
} else {
self.discovered_nodes
.push((*peer.id(), addr.clone(), new_expiration));
}
discovered.push((*peer.id(), addr));
}
}
self.closest_expiration = self
.discovered_nodes
.iter()
.fold(None, |exp, &(_, _, elem_exp)| {
Some(exp.map(|exp| cmp::min(exp, elem_exp)).unwrap_or(elem_exp))
})
.map(Timer::at);
self.events
.push_back(MdnsEvent::Discovered(DiscoveredAddrsIter {
inner: discovered.into_iter(),
}));
}
MdnsPacket::ServiceDiscovery(disc) => {
let resp = build_service_discovery_response(disc.query_id(), self.ttl);
self.send_buffer.push_back(resp);
}
}
}
} }
impl NetworkBehaviour for Mdns { impl NetworkBehaviour for Mdns {
@ -149,12 +277,88 @@ impl NetworkBehaviour for Mdns {
Self::OutEvent, Self::OutEvent,
>, >,
> { > {
// Remove expired peers. while let Poll::Ready(event) = Pin::new(&mut self.if_watch).poll(cx) {
let multicast = From::from([224, 0, 0, 251]);
let socket = self.recv_socket.get_ref();
match event {
Ok(IfEvent::Up(inet)) => {
if inet.addr().is_loopback() {
continue;
}
if let IpAddr::V4(addr) = inet.addr() {
log::trace!("joining multicast on iface {}", addr);
if let Err(err) = socket.join_multicast_v4(&multicast, &addr) {
log::error!("join multicast failed: {}", err);
} else {
self.send_buffer.push_back(build_query());
}
}
}
Ok(IfEvent::Down(inet)) => {
if inet.addr().is_loopback() {
continue;
}
if let IpAddr::V4(addr) = inet.addr() {
log::trace!("leaving multicast on iface {}", addr);
if let Err(err) = socket.leave_multicast_v4(&multicast, &addr) {
log::error!("leave multicast failed: {}", err);
}
}
}
Err(err) => log::error!("if watch returned an error: {}", err),
}
}
// Poll receive socket.
while self.recv_socket.poll_readable(cx).is_ready() {
match self
.recv_socket
.recv_from(&mut self.recv_buffer)
.now_or_never()
{
Some(Ok((len, from))) => {
if let Some(packet) = MdnsPacket::new_from_bytes(&self.recv_buffer[..len], from)
{
self.inject_mdns_packet(packet, params);
}
}
Some(Err(err)) => log::error!("Failed reading datagram: {}", err),
_ => {}
}
}
if Pin::new(&mut self.timeout).poll_next(cx).is_ready() {
self.send_buffer.push_back(build_query());
}
// Send responses.
if !self.send_buffer.is_empty() {
while self.send_socket.poll_writable(cx).is_ready() {
if let Some(packet) = self.send_buffer.pop_front() {
match self
.send_socket
.send_to(&packet, *IPV4_MDNS_MULTICAST_ADDRESS)
.now_or_never()
{
Some(Ok(_)) => {}
Some(Err(err)) => log::error!("{}", err),
None => self.send_buffer.push_front(packet),
}
} else {
break;
}
}
}
// Emit discovered event.
if let Some(event) = self.events.pop_front() {
return Poll::Ready(NetworkBehaviourAction::GenerateEvent(event));
}
// Emit expired event.
if let Some(ref mut closest_expiration) = self.closest_expiration { if let Some(ref mut closest_expiration) = self.closest_expiration {
match Pin::new(closest_expiration).poll(cx) { if let Poll::Ready(now) = Pin::new(closest_expiration).poll(cx) {
Poll::Ready(now) => {
let mut expired = SmallVec::<[(PeerId, Multiaddr); 4]>::new(); let mut expired = SmallVec::<[(PeerId, Multiaddr); 4]>::new();
while let Some(pos) = self.discovered_nodes.iter().position(|(_, _, exp)| *exp < now) { while let Some(pos) = self
.discovered_nodes
.iter()
.position(|(_, _, exp)| *exp < now)
{
let (peer_id, addr, _) = self.discovered_nodes.remove(pos); let (peer_id, addr, _) = self.discovered_nodes.remove(pos);
expired.push((peer_id, addr)); expired.push((peer_id, addr));
} }
@ -166,121 +370,9 @@ impl NetworkBehaviour for Mdns {
return Poll::Ready(NetworkBehaviourAction::GenerateEvent(event)); return Poll::Ready(NetworkBehaviourAction::GenerateEvent(event));
} }
},
Poll::Pending => (),
} }
} }
Poll::Pending
// Polling the mDNS service, and obtain the list of nodes discovered this round.
let discovered = loop {
let service = mem::replace(&mut self.service, MdnsBusyWrapper::Poisoned);
let packet = match service {
MdnsBusyWrapper::Free(service) => {
self.service = MdnsBusyWrapper::Busy(Box::pin(service.next()));
continue;
},
MdnsBusyWrapper::Busy(mut fut) => {
match fut.as_mut().poll(cx) {
Poll::Ready((service, packet)) => {
self.service = MdnsBusyWrapper::Free(service);
packet
},
Poll::Pending => {
self.service = MdnsBusyWrapper::Busy(fut);
return Poll::Pending;
}
}
},
MdnsBusyWrapper::Poisoned => panic!("Mdns poisoned"),
};
match packet {
MdnsPacket::Query(query) => {
// MaybeBusyMdnsService should always be Free.
if let MdnsBusyWrapper::Free(ref mut service) = self.service {
for packet in build_query_response(
query.query_id(),
*params.local_peer_id(),
params.listened_addresses(),
MDNS_RESPONSE_TTL,
) {
service.enqueue_response(packet)
}
} else { debug_assert!(false); }
},
MdnsPacket::Response(response) => {
// We replace the IP address with the address we observe the
// remote as and the address they listen on.
let obs_ip = Protocol::from(response.remote_addr().ip());
let obs_port = Protocol::Udp(response.remote_addr().port());
let observed: Multiaddr = iter::once(obs_ip)
.chain(iter::once(obs_port))
.collect();
let mut discovered: SmallVec<[_; 4]> = SmallVec::new();
for peer in response.discovered_peers() {
if peer.id() == params.local_peer_id() {
continue;
}
let new_expiration = Instant::now() + peer.ttl();
let mut addrs: Vec<Multiaddr> = Vec::new();
for addr in peer.addresses() {
if let Some(new_addr) = address_translation(&addr, &observed) {
addrs.push(new_addr.clone())
}
addrs.push(addr.clone())
}
for addr in addrs {
if let Some((_, _, cur_expires)) = self.discovered_nodes.iter_mut()
.find(|(p, a, _)| p == peer.id() && *a == addr)
{
*cur_expires = cmp::max(*cur_expires, new_expiration);
} else {
self.discovered_nodes.push((*peer.id(), addr.clone(), new_expiration));
}
discovered.push((*peer.id(), addr));
}
}
break discovered;
},
MdnsPacket::ServiceDiscovery(disc) => {
// MaybeBusyMdnsService should always be Free.
if let MdnsBusyWrapper::Free(ref mut service) = self.service {
let resp = build_service_discovery_response(
disc.query_id(),
MDNS_RESPONSE_TTL,
);
service.enqueue_response(resp);
} else { debug_assert!(false); }
},
}
};
// Getting this far implies that we discovered new nodes. As the final step, we need to
// refresh `closest_expiration`.
self.closest_expiration = self.discovered_nodes.iter()
.fold(None, |exp, &(_, _, elem_exp)| {
Some(exp.map(|exp| cmp::min(exp, elem_exp)).unwrap_or(elem_exp))
})
.map(Timer::at);
Poll::Ready(NetworkBehaviourAction::GenerateEvent(MdnsEvent::Discovered(DiscoveredAddrsIter {
inner: discovered.into_iter(),
})))
}
}
impl fmt::Debug for Mdns {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt.debug_struct("Mdns")
.field("service", &self.service)
.finish()
} }
} }
@ -299,7 +391,7 @@ pub enum MdnsEvent {
/// Iterator that produces the list of addresses that have been discovered. /// Iterator that produces the list of addresses that have been discovered.
pub struct DiscoveredAddrsIter { pub struct DiscoveredAddrsIter {
inner: smallvec::IntoIter<[(PeerId, Multiaddr); 4]> inner: smallvec::IntoIter<[(PeerId, Multiaddr); 4]>,
} }
impl Iterator for DiscoveredAddrsIter { impl Iterator for DiscoveredAddrsIter {
@ -316,19 +408,17 @@ impl Iterator for DiscoveredAddrsIter {
} }
} }
impl ExactSizeIterator for DiscoveredAddrsIter { impl ExactSizeIterator for DiscoveredAddrsIter {}
}
impl fmt::Debug for DiscoveredAddrsIter { impl fmt::Debug for DiscoveredAddrsIter {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt.debug_struct("DiscoveredAddrsIter") fmt.debug_struct("DiscoveredAddrsIter").finish()
.finish()
} }
} }
/// Iterator that produces the list of addresses that have expired. /// Iterator that produces the list of addresses that have expired.
pub struct ExpiredAddrsIter { pub struct ExpiredAddrsIter {
inner: smallvec::IntoIter<[(PeerId, Multiaddr); 4]> inner: smallvec::IntoIter<[(PeerId, Multiaddr); 4]>,
} }
impl Iterator for ExpiredAddrsIter { impl Iterator for ExpiredAddrsIter {
@ -345,12 +435,10 @@ impl Iterator for ExpiredAddrsIter {
} }
} }
impl ExactSizeIterator for ExpiredAddrsIter { impl ExactSizeIterator for ExpiredAddrsIter {}
}
impl fmt::Debug for ExpiredAddrsIter { impl fmt::Debug for ExpiredAddrsIter {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result { fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt.debug_struct("ExpiredAddrsIter") fmt.debug_struct("ExpiredAddrsIter").finish()
.finish()
} }
} }

19
protocols/mdns/src/dns.rs
View File

@ -264,7 +264,9 @@ fn append_u16(out: &mut Vec<u8>, value: u16) {
/// be compatible with RFC 1035. /// be compatible with RFC 1035.
fn segment_peer_id(peer_id: String) -> String { fn segment_peer_id(peer_id: String) -> String {
// Guard for the most common case // Guard for the most common case
if peer_id.len() <= MAX_LABEL_LENGTH { return peer_id } if peer_id.len() <= MAX_LABEL_LENGTH {
return peer_id;
}
// This will only perform one allocation except in extreme circumstances. // This will only perform one allocation except in extreme circumstances.
let mut out = String::with_capacity(peer_id.len() + 8); let mut out = String::with_capacity(peer_id.len() + 8);
@ -391,8 +393,10 @@ impl fmt::Display for MdnsResponseError {
MdnsResponseError::TxtRecordTooLong => { MdnsResponseError::TxtRecordTooLong => {
write!(f, "TXT record invalid because it is too long") write!(f, "TXT record invalid because it is too long")
} }
MdnsResponseError::NonAsciiMultiaddr => MdnsResponseError::NonAsciiMultiaddr => write!(
write!(f, "A multiaddr contains non-ASCII characters when serialized"), f,
"A multiaddr contains non-ASCII characters when serialized"
),
} }
} }
} }
@ -414,7 +418,9 @@ mod tests {
#[test] #[test]
fn build_query_response_correct() { fn build_query_response_correct() {
let my_peer_id = identity::Keypair::generate_ed25519().public().into_peer_id(); let my_peer_id = identity::Keypair::generate_ed25519()
.public()
.into_peer_id();
let addr1 = "/ip4/1.2.3.4/tcp/5000".parse().unwrap(); let addr1 = "/ip4/1.2.3.4/tcp/5000".parse().unwrap();
let addr2 = "/ip6/::1/udp/10000".parse().unwrap(); let addr2 = "/ip6/::1/udp/10000".parse().unwrap();
let packets = build_query_response( let packets = build_query_response(
@ -446,7 +452,10 @@ mod tests {
assert_eq!(segment_peer_id(str_63.clone()), str_63); assert_eq!(segment_peer_id(str_63.clone()), str_63);
assert_eq!(segment_peer_id(str_64), [&str_63, "x"].join(".")); assert_eq!(segment_peer_id(str_64), [&str_63, "x"].join("."));
assert_eq!(segment_peer_id(str_126), [&str_63, str_63.as_str()].join(".")); assert_eq!(
segment_peer_id(str_126),
[&str_63, str_63.as_str()].join(".")
);
assert_eq!(segment_peer_id(str_127), [&str_63, &str_63, "x"].join(".")); assert_eq!(segment_peer_id(str_127), [&str_63, &str_63, "x"].join("."));
} }

8
protocols/mdns/src/lib.rs
View File

@ -35,12 +35,8 @@ const SERVICE_NAME: &[u8] = b"_p2p._udp.local";
/// The meta query for looking up the `SERVICE_NAME`. /// The meta query for looking up the `SERVICE_NAME`.
const META_QUERY_SERVICE: &[u8] = b"_services._dns-sd._udp.local"; const META_QUERY_SERVICE: &[u8] = b"_services._dns-sd._udp.local";
pub use crate::{ pub use crate::behaviour::{Mdns, MdnsConfig, MdnsEvent};
behaviour::{Mdns, MdnsEvent},
service::MdnsService,
};
mod behaviour; mod behaviour;
mod dns; mod dns;
mod query;
pub mod service;

305
protocols/mdns/src/query.rs Normal file
View File

@ -0,0 +1,305 @@
// Copyright 2018 Parity Technologies (UK) Ltd.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
use crate::{dns, META_QUERY_SERVICE, SERVICE_NAME};
use dns_parser::{Packet, RData};
use libp2p_core::{
multiaddr::{Multiaddr, Protocol},
PeerId,
};
use std::{convert::TryFrom, fmt, net::SocketAddr, str, time::Duration};
/// A valid mDNS packet received by the service.
#[derive(Debug)]
pub enum MdnsPacket {
/// A query made by a remote.
Query(MdnsQuery),
/// A response sent by a remote in response to one of our queries.
Response(MdnsResponse),
/// A request for service discovery.
ServiceDiscovery(MdnsServiceDiscovery),
}
impl MdnsPacket {
pub fn new_from_bytes(buf: &[u8], from: SocketAddr) -> Option<MdnsPacket> {
match Packet::parse(buf) {
Ok(packet) => {
if packet.header.query {
if packet
.questions
.iter()
.any(|q| q.qname.to_string().as_bytes() == SERVICE_NAME)
{
let query = MdnsPacket::Query(MdnsQuery {
from,
query_id: packet.header.id,
});
Some(query)
} else if packet
.questions
.iter()
.any(|q| q.qname.to_string().as_bytes() == META_QUERY_SERVICE)
{
// TODO: what if multiple questions, one with SERVICE_NAME and one with META_QUERY_SERVICE?
let discovery = MdnsPacket::ServiceDiscovery(MdnsServiceDiscovery {
from,
query_id: packet.header.id,
});
Some(discovery)
} else {
None
}
} else {
let resp = MdnsPacket::Response(MdnsResponse::new(packet, from));
Some(resp)
}
}
Err(err) => {
log::debug!("Parsing mdns packet failed: {:?}", err);
None
}
}
}
}
/// A received mDNS query.
pub struct MdnsQuery {
/// Sender of the address.
from: SocketAddr,
/// Id of the received DNS query. We need to pass this ID back in the results.
query_id: u16,
}
impl MdnsQuery {
/// Source address of the packet.
pub fn remote_addr(&self) -> &SocketAddr {
&self.from
}
/// Query id of the packet.
pub fn query_id(&self) -> u16 {
self.query_id
}
}
impl fmt::Debug for MdnsQuery {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("MdnsQuery")
.field("from", self.remote_addr())
.field("query_id", &self.query_id)
.finish()
}
}
/// A received mDNS service discovery query.
pub struct MdnsServiceDiscovery {
/// Sender of the address.
from: SocketAddr,
/// Id of the received DNS query. We need to pass this ID back in the results.
query_id: u16,
}
impl MdnsServiceDiscovery {
/// Source address of the packet.
pub fn remote_addr(&self) -> &SocketAddr {
&self.from
}
/// Query id of the packet.
pub fn query_id(&self) -> u16 {
self.query_id
}
}
impl fmt::Debug for MdnsServiceDiscovery {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("MdnsServiceDiscovery")
.field("from", self.remote_addr())
.field("query_id", &self.query_id)
.finish()
}
}
/// A received mDNS response.
pub struct MdnsResponse {
peers: Vec<MdnsPeer>,
from: SocketAddr,
}
impl MdnsResponse {
/// Creates a new `MdnsResponse` based on the provided `Packet`.
pub fn new(packet: Packet<'_>, from: SocketAddr) -> MdnsResponse {
let peers = packet
.answers
.iter()
.filter_map(|record| {
if record.name.to_string().as_bytes() != SERVICE_NAME {
return None;
}
let record_value = match record.data {
RData::PTR(record) => record.0.to_string(),
_ => return None,
};
let mut peer_name = match record_value.rsplitn(4, |c| c == '.').last() {
Some(n) => n.to_owned(),
None => return None,
};
// if we have a segmented name, remove the '.'
peer_name.retain(|c| c != '.');
let peer_id = match data_encoding::BASE32_DNSCURVE.decode(peer_name.as_bytes()) {
Ok(bytes) => match PeerId::from_bytes(&bytes) {
Ok(id) => id,
Err(_) => return None,
},
Err(_) => return None,
};
Some(MdnsPeer::new(&packet, record_value, peer_id, record.ttl))
})
.collect();
MdnsResponse { peers, from }
}
/// Returns the list of peers that have been reported in this packet.
///
/// > **Note**: Keep in mind that this will also contain the responses we sent ourselves.
pub fn discovered_peers(&self) -> impl Iterator<Item = &MdnsPeer> {
self.peers.iter()
}
/// Source address of the packet.
#[inline]
pub fn remote_addr(&self) -> &SocketAddr {
&self.from
}
}
impl fmt::Debug for MdnsResponse {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("MdnsResponse")
.field("from", self.remote_addr())
.finish()
}
}
/// A peer discovered by the service.
pub struct MdnsPeer {
addrs: Vec<Multiaddr>,
/// Id of the peer.
peer_id: PeerId,
/// TTL of the record in seconds.
ttl: u32,
}
impl MdnsPeer {
/// Creates a new `MdnsPeer` based on the provided `Packet`.
pub fn new(
packet: &Packet<'_>,
record_value: String,
my_peer_id: PeerId,
ttl: u32,
) -> MdnsPeer {
let addrs = packet
.additional
.iter()
.filter_map(|add_record| {
if add_record.name.to_string() != record_value {
return None;
}
if let RData::TXT(ref txt) = add_record.data {
Some(txt)
} else {
None
}
})
.flat_map(|txt| txt.iter())
.filter_map(|txt| {
// TODO: wrong, txt can be multiple character strings
let addr = match dns::decode_character_string(txt) {
Ok(a) => a,
Err(_) => return None,
};
if !addr.starts_with(b"dnsaddr=") {
return None;
}
let addr = match str::from_utf8(&addr[8..]) {
Ok(a) => a,
Err(_) => return None,
};
let mut addr = match addr.parse::<Multiaddr>() {
Ok(a) => a,
Err(_) => return None,
};
match addr.pop() {
Some(Protocol::P2p(peer_id)) => {
if let Ok(peer_id) = PeerId::try_from(peer_id) {
if peer_id != my_peer_id {
return None;
}
} else {
return None;
}
}
_ => return None,
};
Some(addr)
})
.collect();
MdnsPeer {
addrs,
peer_id: my_peer_id,
ttl,
}
}
/// Returns the id of the peer.
#[inline]
pub fn id(&self) -> &PeerId {
&self.peer_id
}
/// Returns the requested time-to-live for the record.
#[inline]
pub fn ttl(&self) -> Duration {
Duration::from_secs(u64::from(self.ttl))
}
/// Returns the list of addresses the peer says it is listening on.
///
/// Filters out invalid addresses.
pub fn addresses(&self) -> &Vec<Multiaddr> {
&self.addrs
}
}
impl fmt::Debug for MdnsPeer {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("MdnsPeer")
.field("peer_id", &self.peer_id)
.finish()
}
}

709
protocols/mdns/src/service.rs
View File

@ -1,709 +0,0 @@
// Copyright 2018 Parity Technologies (UK) Ltd.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
use crate::{SERVICE_NAME, META_QUERY_SERVICE, dns};
use async_io::{Async, Timer};
use dns_parser::{Packet, RData};
use futures::{prelude::*, select};
use if_watch::{IfEvent, IfWatcher};
use lazy_static::lazy_static;
use libp2p_core::{multiaddr::{Multiaddr, Protocol}, PeerId};
use log::debug;
use socket2::{Socket, Domain, Type};
use std::{convert::TryFrom, fmt, io, net::{IpAddr, Ipv4Addr, UdpSocket, SocketAddr}, str, time::{Duration, Instant}};
pub use dns::{build_query_response, build_service_discovery_response};
lazy_static! {
static ref IPV4_MDNS_MULTICAST_ADDRESS: SocketAddr = SocketAddr::from((
Ipv4Addr::new(224, 0, 0, 251),
5353,
));
}
/// A running service that discovers libp2p peers and responds to other libp2p peers' queries on
/// the local network.
///
/// # Usage
///
/// In order to use mDNS to discover peers on the local network, use the `MdnsService`. This is
/// done by creating a `MdnsService` then polling it in the same way as you would poll a stream.
///
/// Polling the `MdnsService` can produce either an `MdnsQuery`, corresponding to an mDNS query
/// received by another node on the local network, or an `MdnsResponse` corresponding to a response
/// to a query previously emitted locally. The `MdnsService` will automatically produce queries,
/// which means that you will receive responses automatically.
///
/// When you receive an `MdnsQuery`, use the `respond` method to send back an answer to the node
/// that emitted the query.
///
/// When you receive an `MdnsResponse`, use the provided methods to query the information received
/// in the response.
///
/// # Example
///
/// ```rust
/// # use futures::prelude::*;
/// # use futures::executor::block_on;
/// # use libp2p_core::{identity, Multiaddr, PeerId};
/// # use libp2p_mdns::service::{MdnsPacket, build_query_response, build_service_discovery_response};
/// # use std::{io, time::Duration, task::Poll};
/// # fn main() {
/// # let my_peer_id = PeerId::from(identity::Keypair::generate_ed25519().public());
/// # let my_listened_addrs: Vec<Multiaddr> = vec![];
/// # async {
/// # let mut service = libp2p_mdns::service::MdnsService::new().await.unwrap();
/// let _future_to_poll = async {
/// let (mut service, packet) = service.next().await;
///
/// match packet {
/// MdnsPacket::Query(query) => {
/// println!("Query from {:?}", query.remote_addr());
/// let packets = build_query_response(
/// query.query_id(),
/// my_peer_id.clone(),
/// vec![].into_iter(),
/// Duration::from_secs(120),
/// );
/// for packet in packets {
/// service.enqueue_response(packet);
/// }
/// }
/// MdnsPacket::Response(response) => {
/// for peer in response.discovered_peers() {
/// println!("Discovered peer {:?}", peer.id());
/// for addr in peer.addresses() {
/// println!("Address = {:?}", addr);
/// }
/// }
/// }
/// MdnsPacket::ServiceDiscovery(disc) => {
/// let resp = build_service_discovery_response(
/// disc.query_id(),
/// Duration::from_secs(120),
/// );
/// service.enqueue_response(resp);
/// }
/// }
/// };
/// # };
/// # }
pub struct MdnsService {
/// Main socket for listening.
socket: Async<UdpSocket>,
/// Socket for sending queries on the network.
query_socket: Async<UdpSocket>,
/// Interval for sending queries.
query_interval: Timer,
/// Whether we send queries on the network at all.
/// Note that we still need to have an interval for querying, as we need to wake up the socket
/// regularly to recover from errors. Otherwise we could simply use an `Option<Timer>`.
silent: bool,
/// Buffer used for receiving data from the main socket.
/// RFC6762 discourages packets larger than the interface MTU, but allows sizes of up to 9000
/// bytes, if it can be ensured that all participating devices can handle such large packets.
/// For computers with several interfaces and IP addresses responses can easily reach sizes in
/// the range of 3000 bytes, so 4096 seems sensible for now. For more information see
/// [rfc6762](https://tools.ietf.org/html/rfc6762#page-46).
recv_buffer: [u8; 4096],
/// Buffers pending to send on the main socket.
send_buffers: Vec<Vec<u8>>,
/// Buffers pending to send on the query socket.
query_send_buffers: Vec<Vec<u8>>,
/// Iface watch.
if_watch: IfWatcher,
}
impl MdnsService {
/// Starts a new mDNS service.
pub async fn new() -> io::Result<Self> {
Self::new_inner(false).await
}
/// Same as `new`, but we don't automatically send queries on the network.
pub async fn silent() -> io::Result<Self> {
Self::new_inner(true).await
}
/// Starts a new mDNS service.
async fn new_inner(silent: bool) -> io::Result<Self> {
let socket = {
let socket = Socket::new(Domain::ipv4(), Type::dgram(), Some(socket2::Protocol::udp()))?;
socket.set_reuse_address(true)?;
#[cfg(unix)]
socket.set_reuse_port(true)?;
socket.bind(&SocketAddr::new(Ipv4Addr::UNSPECIFIED.into(), 5353).into())?;
let socket = socket.into_udp_socket();
socket.set_multicast_loop_v4(true)?;
socket.set_multicast_ttl_v4(255)?;
Async::new(socket)?
};
// Given that we pass an IP address to bind, which does not need to be resolved, we can
// use std::net::UdpSocket::bind, instead of its async counterpart from async-std.
let query_socket = {
let socket = std::net::UdpSocket::bind((Ipv4Addr::UNSPECIFIED, 0))?;
Async::new(socket)?
};
let if_watch = if_watch::IfWatcher::new().await?;
Ok(Self {
socket,
query_socket,
query_interval: Timer::interval_at(Instant::now(), Duration::from_secs(20)),
silent,
recv_buffer: [0; 4096],
send_buffers: Vec::new(),
query_send_buffers: Vec::new(),
if_watch,
})
}
pub fn enqueue_response(&mut self, rsp: Vec<u8>) {
self.send_buffers.push(rsp);
}
/// Returns a future resolving to itself and the next received `MdnsPacket`.
//
// **Note**: Why does `next` take ownership of itself?
//
// `MdnsService::next` needs to be called from within `NetworkBehaviour`
// implementations. Given that traits cannot have async methods the
// respective `NetworkBehaviour` implementation needs to somehow keep the
// Future returned by `MdnsService::next` across classic `poll`
// invocations. The instance method `next` can either take a reference or
// ownership of itself:
//
// 1. Taking a reference - If `MdnsService::poll` takes a reference to
// `&self` the respective `NetworkBehaviour` implementation would need to
// keep both the Future as well as its `MdnsService` instance across poll
// invocations. Given that in this case the Future would have a reference
// to `MdnsService`, the `NetworkBehaviour` implementation struct would
// need to be self-referential which is not possible without unsafe code in
// Rust.
//
// 2. Taking ownership - Instead `MdnsService::next` takes ownership of
// self and returns it alongside an `MdnsPacket` once the actual future
// resolves, not forcing self-referential structures on the caller.
pub async fn next(mut self) -> (Self, MdnsPacket) {
loop {
// Flush the send buffer of the main socket.
while !self.send_buffers.is_empty() {
let to_send = self.send_buffers.remove(0);
match self.socket.send_to(&to_send, *IPV4_MDNS_MULTICAST_ADDRESS).await {
Ok(bytes_written) => {
debug_assert_eq!(bytes_written, to_send.len());
}
Err(_) => {
// Errors are non-fatal because they can happen for example if we lose
// connection to the network.
self.send_buffers.clear();
break;
}
}
}
// Flush the query send buffer.
while !self.query_send_buffers.is_empty() {
let to_send = self.query_send_buffers.remove(0);
match self.query_socket.send_to(&to_send, *IPV4_MDNS_MULTICAST_ADDRESS).await {
Ok(bytes_written) => {
debug_assert_eq!(bytes_written, to_send.len());
}
Err(_) => {
// Errors are non-fatal because they can happen for example if we lose
// connection to the network.
self.query_send_buffers.clear();
break;
}
}
}
select! {
res = self.socket.recv_from(&mut self.recv_buffer).fuse() => match res {
Ok((len, from)) => {
match MdnsPacket::new_from_bytes(&self.recv_buffer[..len], from) {
Some(packet) => return (self, packet),
None => {},
}
},
Err(_) => {
// Errors are non-fatal and can happen if we get disconnected from the network.
// The query interval will wake up the task at some point so that we can try again.
},
},
_ = self.query_interval.next().fuse() => {
// Ensure underlying task is woken up on the next interval tick.
while let Some(_) = self.query_interval.next().now_or_never() {};
if !self.silent {
let query = dns::build_query();
self.query_send_buffers.push(query.to_vec());
}
},
event = self.if_watch.next().fuse() => {
let multicast = From::from([224, 0, 0, 251]);
let socket = self.socket.get_ref();
match event {
Ok(IfEvent::Up(inet)) => {
if inet.addr().is_loopback() {
continue;
}
if let IpAddr::V4(addr) = inet.addr() {
log::trace!("joining multicast on iface {}", addr);
if let Err(err) = socket.join_multicast_v4(&multicast, &addr) {
log::error!("join multicast failed: {}", err);
}
}
}
Ok(IfEvent::Down(inet)) => {
if inet.addr().is_loopback() {
continue;
}
if let IpAddr::V4(addr) = inet.addr() {
log::trace!("leaving multicast on iface {}", addr);
if let Err(err) = socket.leave_multicast_v4(&multicast, &addr) {
log::error!("leave multicast failed: {}", err);
}
}
}
Err(err) => log::error!("if watch returned an error: {}", err),
}
}
};
}
}
}
impl fmt::Debug for MdnsService {
fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt.debug_struct("$service_name")
.field("silent", &self.silent)
.finish()
}
}
/// A valid mDNS packet received by the service.
#[derive(Debug)]
pub enum MdnsPacket {
/// A query made by a remote.
Query(MdnsQuery),
/// A response sent by a remote in response to one of our queries.
Response(MdnsResponse),
/// A request for service discovery.
ServiceDiscovery(MdnsServiceDiscovery),
}
impl MdnsPacket {
fn new_from_bytes(buf: &[u8], from: SocketAddr) -> Option<MdnsPacket> {
match Packet::parse(buf) {
Ok(packet) => {
if packet.header.query {
if packet
.questions
.iter()
.any(|q| q.qname.to_string().as_bytes() == SERVICE_NAME)
{
let query = MdnsPacket::Query(MdnsQuery {
from,
query_id: packet.header.id,
});
Some(query)
} else if packet
.questions
.iter()
.any(|q| q.qname.to_string().as_bytes() == META_QUERY_SERVICE)
{
// TODO: what if multiple questions, one with SERVICE_NAME and one with META_QUERY_SERVICE?
let discovery = MdnsPacket::ServiceDiscovery(
MdnsServiceDiscovery {
from,
query_id: packet.header.id,
},
);
Some(discovery)
} else {
None
}
} else {
let resp = MdnsPacket::Response(MdnsResponse::new (
packet,
from,
));
Some(resp)
}
}
Err(err) => {
debug!("Parsing mdns packet failed: {:?}", err);
None
}
}
}
}
/// A received mDNS query.
pub struct MdnsQuery {
/// Sender of the address.
from: SocketAddr,
/// Id of the received DNS query. We need to pass this ID back in the results.
query_id: u16,
}
impl MdnsQuery {
/// Source address of the packet.
pub fn remote_addr(&self) -> &SocketAddr {
&self.from
}
/// Query id of the packet.
pub fn query_id(&self) -> u16 {
self.query_id
}
}
impl fmt::Debug for MdnsQuery {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("MdnsQuery")
.field("from", self.remote_addr())
.field("query_id", &self.query_id)
.finish()
}
}
/// A received mDNS service discovery query.
pub struct MdnsServiceDiscovery {
/// Sender of the address.
from: SocketAddr,
/// Id of the received DNS query. We need to pass this ID back in the results.
query_id: u16,
}
impl MdnsServiceDiscovery {
/// Source address of the packet.
pub fn remote_addr(&self) -> &SocketAddr {
&self.from
}
/// Query id of the packet.
pub fn query_id(&self) -> u16 {
self.query_id
}
}
impl fmt::Debug for MdnsServiceDiscovery {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("MdnsServiceDiscovery")
.field("from", self.remote_addr())
.field("query_id", &self.query_id)
.finish()
}
}
/// A received mDNS response.
pub struct MdnsResponse {
peers: Vec<MdnsPeer>,
from: SocketAddr,
}
impl MdnsResponse {
/// Creates a new `MdnsResponse` based on the provided `Packet`.
fn new(packet: Packet<'_>, from: SocketAddr) -> MdnsResponse {
let peers = packet.answers.iter().filter_map(|record| {
if record.name.to_string().as_bytes() != SERVICE_NAME {
return None;
}
let record_value = match record.data {
RData::PTR(record) => record.0.to_string(),
_ => return None,
};
let mut peer_name = match record_value.rsplitn(4, |c| c == '.').last() {
Some(n) => n.to_owned(),
None => return None,
};
// if we have a segmented name, remove the '.'
peer_name.retain(|c| c != '.');
let peer_id = match data_encoding::BASE32_DNSCURVE.decode(peer_name.as_bytes()) {
Ok(bytes) => match PeerId::from_bytes(&bytes) {
Ok(id) => id,
Err(_) => return None,
},
Err(_) => return None,
};
Some(MdnsPeer::new (
&packet,
record_value,
peer_id,
record.ttl,
))
}).collect();
MdnsResponse {
peers,
from,
}
}
/// Returns the list of peers that have been reported in this packet.
///
/// > **Note**: Keep in mind that this will also contain the responses we sent ourselves.
pub fn discovered_peers(&self) -> impl Iterator<Item = &MdnsPeer> {
self.peers.iter()
}
/// Source address of the packet.
#[inline]
pub fn remote_addr(&self) -> &SocketAddr {
&self.from
}
}
impl fmt::Debug for MdnsResponse {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("MdnsResponse")
.field("from", self.remote_addr())
.finish()
}
}
/// A peer discovered by the service.
pub struct MdnsPeer {
addrs: Vec<Multiaddr>,
/// Id of the peer.
peer_id: PeerId,
/// TTL of the record in seconds.
ttl: u32,
}
impl MdnsPeer {
/// Creates a new `MdnsPeer` based on the provided `Packet`.
pub fn new(packet: &Packet<'_>, record_value: String, my_peer_id: PeerId, ttl: u32) -> MdnsPeer {
let addrs = packet
.additional
.iter()
.filter_map(|add_record| {
if add_record.name.to_string() != record_value {
return None;
}
if let RData::TXT(ref txt) = add_record.data {
Some(txt)
} else {
None
}
})
.flat_map(|txt| txt.iter())
.filter_map(|txt| {
// TODO: wrong, txt can be multiple character strings
let addr = match dns::decode_character_string(txt) {
Ok(a) => a,
Err(_) => return None,
};
if !addr.starts_with(b"dnsaddr=") {
return None;
}
let addr = match str::from_utf8(&addr[8..]) {
Ok(a) => a,
Err(_) => return None,
};
let mut addr = match addr.parse::<Multiaddr>() {
Ok(a) => a,
Err(_) => return None,
};
match addr.pop() {
Some(Protocol::P2p(peer_id)) => {
if let Ok(peer_id) = PeerId::try_from(peer_id) {
if peer_id != my_peer_id {
return None;
}
} else {
return None;
}
},
_ => return None,
};
Some(addr)
}).collect();
MdnsPeer {
addrs,
peer_id: my_peer_id,
ttl,
}
}
/// Returns the id of the peer.
#[inline]
pub fn id(&self) -> &PeerId {
&self.peer_id
}
/// Returns the requested time-to-live for the record.
#[inline]
pub fn ttl(&self) -> Duration {
Duration::from_secs(u64::from(self.ttl))
}
/// Returns the list of addresses the peer says it is listening on.
///
/// Filters out invalid addresses.
pub fn addresses(&self) -> &Vec<Multiaddr> {
&self.addrs
}
}
impl fmt::Debug for MdnsPeer {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
f.debug_struct("MdnsPeer")
.field("peer_id", &self.peer_id)
.finish()
}
}
#[cfg(test)]
mod tests {
macro_rules! testgen {
($runtime_name:ident, $service_name:ty, $block_on_fn:tt) => {
mod $runtime_name {
use libp2p_core::{PeerId, multihash::{Code, MultihashDigest}};
use std::time::Duration;
use crate::service::MdnsPacket;
fn discover(peer_id: PeerId) {
let fut = async {
let mut service = <$service_name>::new().await.unwrap();
loop {
let next = service.next().await;
service = next.0;
match next.1 {
MdnsPacket::Query(query) => {
let resp = crate::dns::build_query_response(
query.query_id(),
peer_id.clone(),
vec![].into_iter(),
Duration::from_secs(120),
);
for r in resp {
service.enqueue_response(r);
}
}
MdnsPacket::Response(response) => {
for peer in response.discovered_peers() {
if peer.id() == &peer_id {
return;
}
}
}
MdnsPacket::ServiceDiscovery(_) => panic!(
"did not expect a service discovery packet",
)
}
}
};
$block_on_fn(Box::pin(fut));
}
// As of today the underlying UDP socket is not stubbed out. Thus tests run in parallel to
// this unit tests inter fear with it. Test needs to be run in sequence to ensure test
// properties.
#[test]
fn respect_query_interval() {
let own_ips: Vec<std::net::IpAddr> = if_addrs::get_if_addrs().unwrap()
.into_iter()
.map(|i| i.addr.ip())
.collect();
let fut = async {
let mut service = <$service_name>::new().await.unwrap();
let mut sent_queries = vec![];
loop {
let next = service.next().await;
service = next.0;
match next.1 {
MdnsPacket::Query(query) => {
// Ignore queries from other nodes.
let source_ip = query.remote_addr().ip();
if !own_ips.contains(&source_ip) {
continue;
}
sent_queries.push(query);
if sent_queries.len() > 1 {
return;
}
}
// Ignore response packets. We don't stub out the UDP socket, thus this is
// either random noise from the network, or noise from other unit tests
// running in parallel.
MdnsPacket::Response(_) => {},
MdnsPacket::ServiceDiscovery(_) => {
panic!("Did not expect a service discovery packet.");
},
}
}
};
$block_on_fn(Box::pin(fut));
}
#[test]
fn discover_normal_peer_id() {
discover(PeerId::random())
}
#[test]
fn discover_long_peer_id() {
let max_value = String::from_utf8(vec![b'f'; 42]).unwrap();
let hash = Code::Identity.digest(max_value.as_ref());
discover(PeerId::from_multihash(hash).unwrap())
}
}
}
}
testgen!(
async_std,
crate::service::MdnsService,
(|fut| async_std::task::block_on::<_, ()>(fut))
);
testgen!(
tokio,
crate::service::MdnsService,
(|fut| tokio::runtime::Runtime::new().unwrap().block_on::<futures::future::BoxFuture<()>>(fut))
);
}