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Add a mDNS network behaviour (#736)

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* Move the MdnsService to a service module

* Add a Mdns behaviour

* Add a Mdns network behaviour

* Add minor documentation

* Add minor todo

* Use nat_traversal on the observed address

* Don't add self to topology

* Automatically connect to nodes we discover

* Add Debug implementations

* Fix example
This commit is contained in:
Pierre Krieger
2018-12-10 16:00:16 +01:00
committed by GitHub
parent 460f083a0d
commit d06eb67353
7 changed files with 834 additions and 565 deletions
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11
core/src/swarm.rs
View File

@ -267,11 +267,13 @@ where TBehaviour: NetworkBehaviour<TTopology>,
}
let behaviour_poll = {
let transport = self.raw_swarm.transport();
let mut parameters = PollParameters {
topology: &mut self.topology,
supported_protocols: &self.supported_protocols,
listened_addrs: &self.listened_addrs,
external_addresses: &self.external_addresses,
nat_traversal: &move |a, b| transport.nat_traversal(a, b),
local_public_key: &self.local_public_key,
local_peer_id: &self.raw_swarm.local_peer_id(),
};
@ -345,12 +347,13 @@ pub trait NetworkBehaviour<TTopology> {
}
/// Parameters passed to `poll()` that the `NetworkBehaviour` has access to.
#[derive(Debug)]
// TODO: #[derive(Debug)]
pub struct PollParameters<'a, TTopology: 'a> {
topology: &'a mut TTopology,
supported_protocols: &'a [Vec<u8>],
listened_addrs: &'a [Multiaddr],
external_addresses: &'a [Multiaddr],
nat_traversal: &'a dyn Fn(&Multiaddr, &Multiaddr) -> Option<Multiaddr>,
local_public_key: &'a PublicKey,
local_peer_id: &'a PeerId,
}
@ -398,6 +401,12 @@ impl<'a, TTopology> PollParameters<'a, TTopology> {
pub fn local_peer_id(&self) -> &PeerId {
self.local_peer_id
}
/// Calls the `nat_traversal` method on the underlying transport of the `Swarm`.
#[inline]
pub fn nat_traversal(&self, server: &Multiaddr, observed: &Multiaddr) -> Option<Multiaddr> {
(self.nat_traversal)(server, observed)
}
}
/// Action to perform.

75
examples/chat.rs
View File

@ -18,27 +18,36 @@
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.
//! A basic chat application demonstrating libp2p and the Floodsub protocol.
//! A basic chat application demonstrating libp2p and the mDNS and floodsub protocols.
//!
//! Using two terminal windows, start two instances. Take note of the listening
//! address of the first instance and start the second with this address as the
//! first argument. In the first terminal window, run:
//! ```text
//! cargo run --example chat
//! ```
//! It will print the PeerId and the listening address, e.g. `Listening on
//! "/ip4/0.0.0.0/tcp/24915"`
//!
//! In the second terminal window, start a new instance of the example with:
//! ```text
//! cargo run --example chat -- /ip4/127.0.0.1/tcp/24915
//! ```
//! The two nodes connect. Type a message in either terminal and hit return: the
//! Using two terminal windows, start two instances. If you local network allows mDNS,
//! they will automatically connect. Type a message in either terminal and hit return: the
//! message is sent and printed in the other terminal. Close with Ctrl-c.
//!
//! You can of course open more terminal windows and add more participants.
//! Dialing any of the other peers will propagate the new participant to all
//! chat members and everyone will receive all messages.
//!
//! # If they don't automatically connect
//!
//! If the nodes don't automatically connect, take note of the listening address of the first
//! instance and start the second with this address as the first argument. In the first terminal
//! window, run:
//!
//! ```sh
//! cargo run --example chat
//! ```
//!
//! It will print the PeerId and the listening address, e.g. `Listening on
//! "/ip4/0.0.0.0/tcp/24915"`
//!
//! In the second terminal window, start a new instance of the example with:
//!
//! ```sh
//! cargo run --example chat -- /ip4/127.0.0.1/tcp/24915
//! ```
//!
//! The two nodes then connect.
extern crate env_logger;
extern crate futures;
@ -47,7 +56,7 @@ extern crate tokio;
use futures::prelude::*;
use libp2p::{
Transport,
NetworkBehaviour, Transport,
core::upgrade::{self, OutboundUpgradeExt},
secio,
mplex,
@ -74,10 +83,32 @@ fn main() {
// Create a Floodsub topic
let floodsub_topic = libp2p::floodsub::TopicBuilder::new("chat").build();
// We create a custom network behaviour that combines floodsub and mDNS.
// In the future, we want to improve libp2p to make this easier to do.
#[derive(NetworkBehaviour)]
struct MyBehaviour<TSubstream: libp2p::tokio_io::AsyncRead + libp2p::tokio_io::AsyncWrite> {
#[behaviour(handler = "on_floodsub")]
floodsub: libp2p::floodsub::Floodsub<TSubstream>,
mdns: libp2p::mdns::Mdns<TSubstream>,
}
impl<TSubstream: libp2p::tokio_io::AsyncRead + libp2p::tokio_io::AsyncWrite> MyBehaviour<TSubstream> {
// Called when `floodsub` produces an event.
fn on_floodsub<TTopology>(&mut self, message: <libp2p::floodsub::Floodsub<TSubstream> as libp2p::core::swarm::NetworkBehaviour<TTopology>>::OutEvent)
where TSubstream: libp2p::tokio_io::AsyncRead + libp2p::tokio_io::AsyncWrite
{
println!("Received: '{:?}' from {:?}", String::from_utf8_lossy(&message.data), message.source);
}
}
// Create a Swarm to manage peers and events
let mut swarm = {
let mut behaviour = libp2p::floodsub::Floodsub::new(local_pub_key.clone().into_peer_id());
behaviour.subscribe(floodsub_topic.clone());
let mut behaviour = MyBehaviour {
floodsub: libp2p::floodsub::Floodsub::new(local_pub_key.clone().into_peer_id()),
mdns: libp2p::mdns::Mdns::new().expect("Failed to create mDNS service"),
};
behaviour.floodsub.subscribe(floodsub_topic.clone());
libp2p::Swarm::new(transport, behaviour, libp2p::core::topology::MemoryTopology::empty(), local_pub_key)
};
@ -85,7 +116,7 @@ fn main() {
let addr = libp2p::Swarm::listen_on(&mut swarm, "/ip4/0.0.0.0/tcp/0".parse().unwrap()).unwrap();
println!("Listening on {:?}", addr);
// Reach out to another node
// Reach out to another node if specified
if let Some(to_dial) = std::env::args().nth(1) {
let dialing = to_dial.clone();
match to_dial.parse() {
@ -107,7 +138,7 @@ fn main() {
tokio::run(futures::future::poll_fn(move || -> Result<_, ()> {
loop {
match framed_stdin.poll().expect("Error while polling stdin") {
Async::Ready(Some(line)) => swarm.publish(&floodsub_topic, line.as_bytes()),
Async::Ready(Some(line)) => swarm.floodsub.publish(&floodsub_topic, line.as_bytes()),
Async::Ready(None) => panic!("Stdin closed"),
Async::NotReady => break,
};
@ -115,8 +146,8 @@ fn main() {
loop {
match swarm.poll().expect("Error while polling swarm") {
Async::Ready(Some(message)) => {
println!("Received: '{:?}' from {:?}", String::from_utf8_lossy(&message.data), message.source);
Async::Ready(Some(_)) => {
},
Async::Ready(None) | Async::NotReady => break,
}

2
examples/mdns-passive-discovery.rs
View File

@ -24,7 +24,7 @@ extern crate rand;
extern crate tokio;
use futures::prelude::*;
use libp2p::mdns::{MdnsPacket, MdnsService};
use libp2p::mdns::service::{MdnsPacket, MdnsService};
use std::io;
fn main() {

3
misc/mdns/Cargo.toml
View File

@ -16,9 +16,12 @@ libp2p-core = { path = "../../core" }
multiaddr = { package = "parity-multiaddr", path = "../multiaddr" }
net2 = "0.2"
rand = "0.6"
smallvec = "0.6"
tokio-io = "0.1"
tokio-reactor = "0.1"
tokio-timer = "0.2"
tokio-udp = "0.1"
void = "1.0"
[dev-dependencies]
tokio = "0.1"

171
misc/mdns/src/behaviour.rs Normal file
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@ -0,0 +1,171 @@
// 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::{MdnsService, MdnsPacket};
use futures::prelude::*;
use libp2p_core::protocols_handler::{DummyProtocolsHandler, ProtocolsHandler};
use libp2p_core::swarm::{ConnectedPoint, NetworkBehaviour, NetworkBehaviourAction, PollParameters};
use libp2p_core::{Multiaddr, PeerId, multiaddr::Protocol, topology::MemoryTopology};
use smallvec::SmallVec;
use std::{fmt, io, iter, marker::PhantomData, time::Duration};
use tokio_io::{AsyncRead, AsyncWrite};
use void::{self, Void};
/// A `NetworkBehaviour` for mDNS. Automatically discovers peers on the local network and adds
/// them to the topology.
pub struct Mdns<TSubstream> {
/// The inner service.
service: MdnsService,
/// If `Some`, then we automatically connect to nodes we discover and this is the list of nodes
/// to connect to. Drained in `poll()`.
/// If `None`, then we don't automatically connect.
to_connect_to: Option<SmallVec<[PeerId; 8]>>,
/// Marker to pin the generic.
marker: PhantomData<TSubstream>,
}
impl<TSubstream> Mdns<TSubstream> {
/// Builds a new `Mdns` behaviour.
pub fn new() -> io::Result<Mdns<TSubstream>> {
Ok(Mdns {
service: MdnsService::new()?,
to_connect_to: Some(SmallVec::new()),
marker: PhantomData,
})
}
}
/// Trait that must be implemented on the network topology for it to be usable with `Mdns`.
pub trait MdnsTopology {
/// Adds an address discovered by mDNS.
///
/// Will never be called with the local peer ID.
fn add_mdns_discovered_address(&mut self, peer: PeerId, addr: Multiaddr);
}
impl MdnsTopology for MemoryTopology {
#[inline]
fn add_mdns_discovered_address(&mut self, peer: PeerId, addr: Multiaddr) {
self.add_address(peer, addr)
}
}
impl<TSubstream, TTopology> NetworkBehaviour<TTopology> for Mdns<TSubstream>
where
TSubstream: AsyncRead + AsyncWrite,
TTopology: MdnsTopology,
{
type ProtocolsHandler = DummyProtocolsHandler<TSubstream>;
type OutEvent = Void;
fn new_handler(&mut self) -> Self::ProtocolsHandler {
DummyProtocolsHandler::default()
}
fn inject_connected(&mut self, _: PeerId, _: ConnectedPoint) {}
fn inject_disconnected(&mut self, _: &PeerId, _: ConnectedPoint) {}
fn inject_node_event(
&mut self,
_: PeerId,
_ev: <Self::ProtocolsHandler as ProtocolsHandler>::OutEvent,
) {
void::unreachable(_ev)
}
fn poll(
&mut self,
params: &mut PollParameters<TTopology>,
) -> Async<
NetworkBehaviourAction<
<Self::ProtocolsHandler as ProtocolsHandler>::InEvent,
Self::OutEvent,
>,
> {
loop {
if let Some(ref mut to_connect_to) = self.to_connect_to {
if !to_connect_to.is_empty() {
let peer_id = to_connect_to.remove(0);
return Async::Ready(NetworkBehaviourAction::DialPeer { peer_id });
} else {
to_connect_to.shrink_to_fit();
}
}
let event = match self.service.poll() {
Async::Ready(ev) => ev,
Async::NotReady => return Async::NotReady,
};
match event {
MdnsPacket::Query(query) => {
let _ = query.respond(
params.local_peer_id().clone(),
params.listened_addresses().cloned(),
Duration::from_secs(5 * 60)
);
},
MdnsPacket::Response(response) => {
// We perform a call to `nat_traversal()` 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();
for peer in response.discovered_peers() {
if peer.id() == params.local_peer_id() {
continue;
}
for addr in peer.addresses() {
let to_insert = if let Some(new_addr) = params.nat_traversal(&addr, &observed) {
new_addr
} else {
addr
};
params.topology().add_mdns_discovered_address(peer.id().clone(), to_insert);
}
if let Some(ref mut to_connect_to) = self.to_connect_to {
to_connect_to.push(peer.id().clone());
}
}
},
MdnsPacket::ServiceDiscovery(disc) => {
disc.respond(Duration::from_secs(5 * 60));
},
}
}
}
}
impl<TSubstream> fmt::Debug for Mdns<TSubstream> {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
fmt.debug_struct("Mdns")
.field("service", &self.service)
.finish()
}
}

551
misc/mdns/src/lib.rs
View File

@ -26,64 +26,9 @@
//!
//! # 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.
//! This crate provides the `Mdns` struct which implements the `NetworkBehaviour` trait. This
//! struct will automatically discover other libp2p nodes on the local network.
//!
//! 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
//! # extern crate futures;
//! # extern crate libp2p_core;
//! # extern crate libp2p_mdns;
//! # use futures::prelude::*;
//! # use libp2p_mdns::{MdnsService, MdnsPacket};
//! # use std::{io, time::Duration};
//! # fn main() {
//! # let my_peer_id = libp2p_core::PublicKey::Rsa(vec![1, 2, 3, 4]).into_peer_id();
//! # let my_listened_addrs = Vec::new();
//! let mut service = MdnsService::new().expect("Error while creating mDNS service");
//! let _future_to_poll = futures::stream::poll_fn(move || -> Poll<Option<()>, io::Error> {
//! loop {
//! let packet = match service.poll() {
//! Async::Ready(packet) => packet,
//! Async::NotReady => return Ok(Async::NotReady),
//! };
//!
//! match packet {
//! MdnsPacket::Query(query) => {
//! println!("Query from {:?}", query.remote_addr());
//! query.respond(
//! my_peer_id.clone(),
//! my_listened_addrs.clone(),
//! Duration::from_secs(120),
//! );
//! }
//! MdnsPacket::Response(response) => {
//! for peer in response.discovered_peers() {
//! println!("Discovered peer {:?}", peer.id());
//! for addr in peer.addresses() {
//! println!("Address = {:?}", addr);
//! }
//! }
//! }
//! MdnsPacket::ServiceDiscovery(query) => {
//! query.respond(std::time::Duration::from_secs(120));
//! }
//! }
//! }
//! }).for_each(|_| Ok(()));
//! # }
extern crate data_encoding;
extern crate dns_parser;
@ -92,501 +37,25 @@ extern crate libp2p_core;
extern crate multiaddr;
extern crate net2;
extern crate rand;
extern crate smallvec;
extern crate tokio_io;
extern crate tokio_reactor;
extern crate tokio_timer;
extern crate tokio_udp;
extern crate void;
#[cfg(test)]
extern crate tokio;
use dns_parser::{Packet, RData};
use futures::{prelude::*, task};
use libp2p_core::{Multiaddr, PeerId};
use multiaddr::Protocol;
use std::{fmt, io, net::Ipv4Addr, net::SocketAddr, str, time::Duration, time::Instant};
use tokio_reactor::Handle;
use tokio_timer::Interval;
use tokio_udp::UdpSocket;
pub use dns::MdnsResponseError;
mod dns;
/// Hardcoded name of the mDNS service. Part of the mDNS libp2p specifications.
const SERVICE_NAME: &'static [u8] = b"_p2p._udp.local";
/// Hardcoded name of the service used for DNS-SD.
const META_QUERY_SERVICE: &'static [u8] = b"_services._dns-sd._udp.local";
/// A running service that discovers libp2p peers and responds to other libp2p peers' queries on
/// the local network.
///
/// See the crate root documentation for more info.
pub struct MdnsService {
/// Main socket for listening.
socket: UdpSocket,
/// Socket for sending queries on the network.
query_socket: UdpSocket,
/// Interval for sending queries.
query_interval: Interval,
/// 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<Interval>`.
silent: bool,
/// Buffer used for receiving data from the main socket.
recv_buffer: [u8; 2048],
/// 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>>,
}
pub use self::behaviour::{Mdns, MdnsTopology};
pub use self::service::MdnsService;
impl MdnsService {
/// Starts a new mDNS service.
#[inline]
pub fn new() -> io::Result<MdnsService> {
Self::new_inner(false)
}
mod behaviour;
mod dns;
/// Same as `new`, but we don't send automatically send queries on the network.
#[inline]
pub fn silent() -> io::Result<MdnsService> {
Self::new_inner(true)
}
/// Starts a new mDNS service.
fn new_inner(silent: bool) -> io::Result<MdnsService> {
let socket = {
#[cfg(unix)]
fn platform_specific(s: &net2::UdpBuilder) -> io::Result<()> {
net2::unix::UnixUdpBuilderExt::reuse_port(s, true)?;
Ok(())
}
#[cfg(not(unix))]
fn platform_specific(_: &net2::UdpBuilder) -> io::Result<()> { Ok(()) }
let builder = net2::UdpBuilder::new_v4()?;
builder.reuse_address(true)?;
platform_specific(&builder)?;
builder.bind(("0.0.0.0", 5353))?
};
let socket = UdpSocket::from_std(socket, &Handle::default())?;
socket.set_multicast_loop_v4(true)?;
socket.set_multicast_ttl_v4(255)?;
// TODO: correct interfaces?
socket.join_multicast_v4(&From::from([224, 0, 0, 251]), &Ipv4Addr::UNSPECIFIED)?;
Ok(MdnsService {
socket,
query_socket: UdpSocket::bind(&From::from(([0, 0, 0, 0], 0)))?,
query_interval: Interval::new(Instant::now(), Duration::from_secs(20)),
silent,
recv_buffer: [0; 2048],
send_buffers: Vec::new(),
query_send_buffers: Vec::new(),
})
}
/// Polls the service for packets.
pub fn poll(&mut self) -> Async<MdnsPacket> {
// Send a query every time `query_interval` fires.
// Note that we don't use a loop here ; it is pretty unlikely that we need it, and there is
// no point in sending multiple requests in a row.
match self.query_interval.poll() {
Ok(Async::Ready(_)) => {
if !self.silent {
let query = dns::build_query();
self.query_send_buffers.push(query.to_vec());
}
}
Ok(Async::NotReady) => (),
_ => unreachable!("A tokio_timer::Interval never errors"), // TODO: is that true?
};
// 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
.poll_send_to(&to_send, &From::from(([224, 0, 0, 251], 5353)))
{
Ok(Async::Ready(bytes_written)) => {
debug_assert_eq!(bytes_written, to_send.len());
}
Ok(Async::NotReady) => {
self.send_buffers.insert(0, to_send);
break;
}
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.
// This has to be after the push to `query_send_buffers`.
while !self.query_send_buffers.is_empty() {
let to_send = self.query_send_buffers.remove(0);
match self
.query_socket
.poll_send_to(&to_send, &From::from(([224, 0, 0, 251], 5353)))
{
Ok(Async::Ready(bytes_written)) => {
debug_assert_eq!(bytes_written, to_send.len());
}
Ok(Async::NotReady) => {
self.query_send_buffers.insert(0, to_send);
break;
}
Err(_) => {
// Errors are non-fatal because they can happen for example if we lose
// connection to the network.
self.query_send_buffers.clear();
break;
}
}
}
// Check for any incoming packet.
match self.socket.poll_recv_from(&mut self.recv_buffer) {
Ok(Async::Ready((len, from))) => {
match Packet::parse(&self.recv_buffer[..len]) {
Ok(packet) => {
if packet.header.query {
if packet
.questions
.iter()
.any(|q| q.qname.to_string().as_bytes() == SERVICE_NAME)
{
return Async::Ready(MdnsPacket::Query(MdnsQuery {
from,
query_id: packet.header.id,
send_buffers: &mut self.send_buffers,
}));
} 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?
return Async::Ready(MdnsPacket::ServiceDiscovery(
MdnsServiceDiscovery {
from,
query_id: packet.header.id,
send_buffers: &mut self.send_buffers,
},
));
} else {
// Note that ideally we would use a loop instead. However as of the
// writing of this code non-lexical lifetimes haven't been merged
// yet, and I can't manage to write this code without having borrow
// issues.
task::current().notify();
return Async::NotReady;
}
} else {
return Async::Ready(MdnsPacket::Response(MdnsResponse {
packet,
from,
}));
}
}
Err(_) => {
// Ignore errors while parsing the packet. We need to poll again for the
// next packet.
// Note that ideally we would use a loop instead. However as of the writing
// of this code non-lexical lifetimes haven't been merged yet, and I can't
// manage to write this code without having borrow issues.
task::current().notify();
return Async::NotReady;
}
}
}
Ok(Async::NotReady) => (),
Err(_) => {
// Error are non-fatal and can happen if we get disconnected from example.
// The query interval will wake up the task at some point so that we can try again.
}
};
Async::NotReady
}
}
/// A valid mDNS packet received by the service.
#[derive(Debug)]
pub enum MdnsPacket<'a> {
/// A query made by a remote.
Query(MdnsQuery<'a>),
/// A response sent by a remote in response to one of our queries.
Response(MdnsResponse<'a>),
/// A request for service discovery.
ServiceDiscovery(MdnsServiceDiscovery<'a>),
}
/// A received mDNS query.
pub struct MdnsQuery<'a> {
/// 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,
/// Queue of pending buffers.
send_buffers: &'a mut Vec<Vec<u8>>,
}
impl<'a> MdnsQuery<'a> {
/// Respond to the query.
///
/// Pass the ID of the local peer, and the list o addresses we're listening on.
///
/// If there are more than 2^16-1 addresses, ignores the others.
///
/// > **Note**: Keep in mind that we will also receive this response in an `MdnsResponse`.
#[inline]
pub fn respond<TAddresses>(
self,
peer_id: PeerId,
addresses: TAddresses,
ttl: Duration,
) -> Result<(), MdnsResponseError>
where
TAddresses: IntoIterator<Item = Multiaddr>,
TAddresses::IntoIter: ExactSizeIterator,
{
let response =
dns::build_query_response(self.query_id, peer_id, addresses.into_iter(), ttl)?;
self.send_buffers.push(response);
Ok(())
}
/// Source address of the packet.
#[inline]
pub fn remote_addr(&self) -> &SocketAddr {
&self.from
}
}
impl<'a> fmt::Debug for MdnsQuery<'a> {
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<'a> {
/// 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,
/// Queue of pending buffers.
send_buffers: &'a mut Vec<Vec<u8>>,
}
impl<'a> MdnsServiceDiscovery<'a> {
/// Respond to the query.
#[inline]
pub fn respond(self, ttl: Duration) {
let response = dns::build_service_discovery_response(self.query_id, ttl);
self.send_buffers.push(response);
}
/// Source address of the packet.
#[inline]
pub fn remote_addr(&self) -> &SocketAddr {
&self.from
}
}
impl<'a> fmt::Debug for MdnsServiceDiscovery<'a> {
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<'a> {
packet: Packet<'a>,
from: SocketAddr,
}
impl<'a> MdnsResponse<'a> {
/// 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<'b>(&'b self) -> impl Iterator<Item = MdnsPeer<'b>> {
let packet = &self.packet;
self.packet.answers.iter().filter_map(move |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 peer_name = {
let mut iter = record_value.splitn(2, |c| c == '.');
let name = match iter.next() {
Some(n) => n.to_owned(),
None => return None,
};
if iter.next().map(|v| v.as_bytes()) != Some(SERVICE_NAME) {
return None;
}
name
};
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 {
packet,
record_value,
peer_id,
})
})
}
/// Source address of the packet.
#[inline]
pub fn remote_addr(&self) -> &SocketAddr {
&self.from
}
}
impl<'a> fmt::Debug for MdnsResponse<'a> {
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<'a> {
/// The original packet ; will be used to determine the addresses.
packet: &'a Packet<'a>,
/// Cached value of `concat(base32(peer_id), service name)`.
record_value: String,
/// Id of the peer.
peer_id: PeerId,
}
impl<'a> MdnsPeer<'a> {
/// Returns the id of the peer.
#[inline]
pub fn id(&self) -> &PeerId {
&self.peer_id
}
/// Returns the list of addresses the peer says it is listening on.
///
/// Filters out invalid addresses.
pub fn addresses<'b>(&'b self) -> impl Iterator<Item = Multiaddr> + 'b {
let my_peer_id = &self.peer_id;
let record_value = &self.record_value;
self.packet
.additional
.iter()
.filter_map(move |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(move |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(ref peer_id)) if peer_id == my_peer_id => (),
_ => return None,
};
Some(addr)
})
}
}
impl<'a> fmt::Debug for MdnsPeer<'a> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_struct("MdnsPeer")
.field("peer_id", &self.peer_id)
.finish()
}
}
#[cfg(test)]
mod tests {
use libp2p_core::PublicKey;
use std::{io, time::Duration};
use tokio::{self, prelude::*};
use {MdnsPacket, MdnsService};
#[test]
fn discover_ourselves() {
let mut service = MdnsService::new().unwrap();
let peer_id =
PublicKey::Rsa((0..32).map(|_| rand::random::<u8>()).collect()).into_peer_id();
let stream = stream::poll_fn(move || -> Poll<Option<()>, io::Error> {
loop {
let packet = match service.poll() {
Async::Ready(packet) => packet,
Async::NotReady => return Ok(Async::NotReady),
};
match packet {
MdnsPacket::Query(query) => {
query.respond(peer_id.clone(), None, Duration::from_secs(120)).unwrap();
}
MdnsPacket::Response(response) => {
for peer in response.discovered_peers() {
if peer.id() == &peer_id {
return Ok(Async::Ready(None));
}
}
}
MdnsPacket::ServiceDiscovery(_) => {}
}
}
});
tokio::run(
stream
.map_err(|err| panic!("{:?}", err))
.for_each(|_| Ok(())),
);
}
}
pub mod service;

586
misc/mdns/src/service.rs Normal file
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@ -0,0 +1,586 @@
// 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.
extern crate data_encoding;
extern crate dns_parser;
extern crate futures;
extern crate libp2p_core;
extern crate multiaddr;
extern crate net2;
extern crate rand;
extern crate tokio_reactor;
extern crate tokio_timer;
extern crate tokio_udp;
#[cfg(test)]
extern crate tokio;
use crate::{SERVICE_NAME, META_QUERY_SERVICE, dns};
use dns_parser::{Packet, RData};
use futures::{prelude::*, task};
use libp2p_core::{Multiaddr, PeerId};
use multiaddr::Protocol;
use std::{fmt, io, net::Ipv4Addr, net::SocketAddr, str, time::Duration, time::Instant};
use tokio_reactor::Handle;
use tokio_timer::Interval;
use tokio_udp::UdpSocket;
pub use dns::MdnsResponseError;
/// 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
/// # extern crate futures;
/// # extern crate libp2p_core;
/// # extern crate libp2p_mdns;
/// # use futures::prelude::*;
/// # use libp2p_mdns::service::{MdnsService, MdnsPacket};
/// # use std::{io, time::Duration};
/// # fn main() {
/// # let my_peer_id = libp2p_core::PublicKey::Rsa(vec![1, 2, 3, 4]).into_peer_id();
/// # let my_listened_addrs = Vec::new();
/// let mut service = MdnsService::new().expect("Error while creating mDNS service");
/// let _future_to_poll = futures::stream::poll_fn(move || -> Poll<Option<()>, io::Error> {
/// loop {
/// let packet = match service.poll() {
/// Async::Ready(packet) => packet,
/// Async::NotReady => return Ok(Async::NotReady),
/// };
///
/// match packet {
/// MdnsPacket::Query(query) => {
/// println!("Query from {:?}", query.remote_addr());
/// query.respond(
/// my_peer_id.clone(),
/// my_listened_addrs.clone(),
/// Duration::from_secs(120),
/// );
/// }
/// MdnsPacket::Response(response) => {
/// for peer in response.discovered_peers() {
/// println!("Discovered peer {:?}", peer.id());
/// for addr in peer.addresses() {
/// println!("Address = {:?}", addr);
/// }
/// }
/// }
/// MdnsPacket::ServiceDiscovery(query) => {
/// query.respond(std::time::Duration::from_secs(120));
/// }
/// }
/// }
/// }).for_each(|_| Ok(()));
/// # }
pub struct MdnsService {
/// Main socket for listening.
socket: UdpSocket,
/// Socket for sending queries on the network.
query_socket: UdpSocket,
/// Interval for sending queries.
query_interval: Interval,
/// 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<Interval>`.
silent: bool,
/// Buffer used for receiving data from the main socket.
recv_buffer: [u8; 2048],
/// 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>>,
}
impl MdnsService {
/// Starts a new mDNS service.
#[inline]
pub fn new() -> io::Result<MdnsService> {
Self::new_inner(false)
}
/// Same as `new`, but we don't send automatically send queries on the network.
#[inline]
pub fn silent() -> io::Result<MdnsService> {
Self::new_inner(true)
}
/// Starts a new mDNS service.
fn new_inner(silent: bool) -> io::Result<MdnsService> {
let socket = {
#[cfg(unix)]
fn platform_specific(s: &net2::UdpBuilder) -> io::Result<()> {
net2::unix::UnixUdpBuilderExt::reuse_port(s, true)?;
Ok(())
}
#[cfg(not(unix))]
fn platform_specific(_: &net2::UdpBuilder) -> io::Result<()> { Ok(()) }
let builder = net2::UdpBuilder::new_v4()?;
builder.reuse_address(true)?;
platform_specific(&builder)?;
builder.bind(("0.0.0.0", 5353))?
};
let socket = UdpSocket::from_std(socket, &Handle::default())?;
socket.set_multicast_loop_v4(true)?;
socket.set_multicast_ttl_v4(255)?;
// TODO: correct interfaces?
socket.join_multicast_v4(&From::from([224, 0, 0, 251]), &Ipv4Addr::UNSPECIFIED)?;
Ok(MdnsService {
socket,
query_socket: UdpSocket::bind(&From::from(([0, 0, 0, 0], 0)))?,
query_interval: Interval::new(Instant::now(), Duration::from_secs(20)),
silent,
recv_buffer: [0; 2048],
send_buffers: Vec::new(),
query_send_buffers: Vec::new(),
})
}
/// Polls the service for packets.
pub fn poll(&mut self) -> Async<MdnsPacket> {
// Send a query every time `query_interval` fires.
// Note that we don't use a loop here ; it is pretty unlikely that we need it, and there is
// no point in sending multiple requests in a row.
match self.query_interval.poll() {
Ok(Async::Ready(_)) => {
if !self.silent {
let query = dns::build_query();
self.query_send_buffers.push(query.to_vec());
}
}
Ok(Async::NotReady) => (),
_ => unreachable!("A tokio_timer::Interval never errors"), // TODO: is that true?
};
// 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
.poll_send_to(&to_send, &From::from(([224, 0, 0, 251], 5353)))
{
Ok(Async::Ready(bytes_written)) => {
debug_assert_eq!(bytes_written, to_send.len());
}
Ok(Async::NotReady) => {
self.send_buffers.insert(0, to_send);
break;
}
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.
// This has to be after the push to `query_send_buffers`.
while !self.query_send_buffers.is_empty() {
let to_send = self.query_send_buffers.remove(0);
match self
.query_socket
.poll_send_to(&to_send, &From::from(([224, 0, 0, 251], 5353)))
{
Ok(Async::Ready(bytes_written)) => {
debug_assert_eq!(bytes_written, to_send.len());
}
Ok(Async::NotReady) => {
self.query_send_buffers.insert(0, to_send);
break;
}
Err(_) => {
// Errors are non-fatal because they can happen for example if we lose
// connection to the network.
self.query_send_buffers.clear();
break;
}
}
}
// Check for any incoming packet.
match self.socket.poll_recv_from(&mut self.recv_buffer) {
Ok(Async::Ready((len, from))) => {
match Packet::parse(&self.recv_buffer[..len]) {
Ok(packet) => {
if packet.header.query {
if packet
.questions
.iter()
.any(|q| q.qname.to_string().as_bytes() == SERVICE_NAME)
{
return Async::Ready(MdnsPacket::Query(MdnsQuery {
from,
query_id: packet.header.id,
send_buffers: &mut self.send_buffers,
}));
} 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?
return Async::Ready(MdnsPacket::ServiceDiscovery(
MdnsServiceDiscovery {
from,
query_id: packet.header.id,
send_buffers: &mut self.send_buffers,
},
));
} else {
// Note that ideally we would use a loop instead. However as of the
// writing of this code non-lexical lifetimes haven't been merged
// yet, and I can't manage to write this code without having borrow
// issues.
task::current().notify();
return Async::NotReady;
}
} else {
return Async::Ready(MdnsPacket::Response(MdnsResponse {
packet,
from,
}));
}
}
Err(_) => {
// Ignore errors while parsing the packet. We need to poll again for the
// next packet.
// Note that ideally we would use a loop instead. However as of the writing
// of this code non-lexical lifetimes haven't been merged yet, and I can't
// manage to write this code without having borrow issues.
task::current().notify();
return Async::NotReady;
}
}
}
Ok(Async::NotReady) => (),
Err(_) => {
// Error are non-fatal and can happen if we get disconnected from example.
// The query interval will wake up the task at some point so that we can try again.
}
};
Async::NotReady
}
}
impl fmt::Debug for MdnsService {
fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
fmt.debug_struct("MdnsService")
.field("silent", &self.silent)
.finish()
}
}
/// A valid mDNS packet received by the service.
#[derive(Debug)]
pub enum MdnsPacket<'a> {
/// A query made by a remote.
Query(MdnsQuery<'a>),
/// A response sent by a remote in response to one of our queries.
Response(MdnsResponse<'a>),
/// A request for service discovery.
ServiceDiscovery(MdnsServiceDiscovery<'a>),
}
/// A received mDNS query.
pub struct MdnsQuery<'a> {
/// 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,
/// Queue of pending buffers.
send_buffers: &'a mut Vec<Vec<u8>>,
}
impl<'a> MdnsQuery<'a> {
/// Respond to the query.
///
/// Pass the ID of the local peer, and the list of addresses we're listening on.
///
/// If there are more than 2^16-1 addresses, ignores the others.
///
/// > **Note**: Keep in mind that we will also receive this response in an `MdnsResponse`.
#[inline]
pub fn respond<TAddresses>(
self,
peer_id: PeerId,
addresses: TAddresses,
ttl: Duration,
) -> Result<(), MdnsResponseError>
where
TAddresses: IntoIterator<Item = Multiaddr>,
TAddresses::IntoIter: ExactSizeIterator,
{
let response =
dns::build_query_response(self.query_id, peer_id, addresses.into_iter(), ttl)?;
self.send_buffers.push(response);
Ok(())
}
/// Source address of the packet.
#[inline]
pub fn remote_addr(&self) -> &SocketAddr {
&self.from
}
}
impl<'a> fmt::Debug for MdnsQuery<'a> {
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<'a> {
/// 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,
/// Queue of pending buffers.
send_buffers: &'a mut Vec<Vec<u8>>,
}
impl<'a> MdnsServiceDiscovery<'a> {
/// Respond to the query.
#[inline]
pub fn respond(self, ttl: Duration) {
let response = dns::build_service_discovery_response(self.query_id, ttl);
self.send_buffers.push(response);
}
/// Source address of the packet.
#[inline]
pub fn remote_addr(&self) -> &SocketAddr {
&self.from
}
}
impl<'a> fmt::Debug for MdnsServiceDiscovery<'a> {
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<'a> {
packet: Packet<'a>,
from: SocketAddr,
}
impl<'a> MdnsResponse<'a> {
/// 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<'b>(&'b self) -> impl Iterator<Item = MdnsPeer<'b>> {
let packet = &self.packet;
self.packet.answers.iter().filter_map(move |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 peer_name = {
let mut iter = record_value.splitn(2, |c| c == '.');
let name = match iter.next() {
Some(n) => n.to_owned(),
None => return None,
};
if iter.next().map(|v| v.as_bytes()) != Some(SERVICE_NAME) {
return None;
}
name
};
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 {
packet,
record_value,
peer_id,
})
})
}
/// Source address of the packet.
#[inline]
pub fn remote_addr(&self) -> &SocketAddr {
&self.from
}
}
impl<'a> fmt::Debug for MdnsResponse<'a> {
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<'a> {
/// The original packet ; will be used to determine the addresses.
packet: &'a Packet<'a>,
/// Cached value of `concat(base32(peer_id), service name)`.
record_value: String,
/// Id of the peer.
peer_id: PeerId,
}
impl<'a> MdnsPeer<'a> {
/// Returns the id of the peer.
#[inline]
pub fn id(&self) -> &PeerId {
&self.peer_id
}
/// Returns the list of addresses the peer says it is listening on.
///
/// Filters out invalid addresses.
pub fn addresses<'b>(&'b self) -> impl Iterator<Item = Multiaddr> + 'b {
let my_peer_id = &self.peer_id;
let record_value = &self.record_value;
self.packet
.additional
.iter()
.filter_map(move |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(move |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(ref peer_id)) if peer_id == my_peer_id => (),
_ => return None,
};
Some(addr)
})
}
}
impl<'a> fmt::Debug for MdnsPeer<'a> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
f.debug_struct("MdnsPeer")
.field("peer_id", &self.peer_id)
.finish()
}
}
#[cfg(test)]
mod tests {
use libp2p_core::PublicKey;
use std::{io, time::Duration};
use tokio::{self, prelude::*};
use crate::service::{MdnsPacket, MdnsService};
#[test]
fn discover_ourselves() {
let mut service = MdnsService::new().unwrap();
let peer_id =
PublicKey::Rsa((0..32).map(|_| rand::random::<u8>()).collect()).into_peer_id();
let stream = stream::poll_fn(move || -> Poll<Option<()>, io::Error> {
loop {
let packet = match service.poll() {
Async::Ready(packet) => packet,
Async::NotReady => return Ok(Async::NotReady),
};
match packet {
MdnsPacket::Query(query) => {
query.respond(peer_id.clone(), None, Duration::from_secs(120)).unwrap();
}
MdnsPacket::Response(response) => {
for peer in response.discovered_peers() {
if peer.id() == &peer_id {
return Ok(Async::Ready(None));
}
}
}
MdnsPacket::ServiceDiscovery(_) => {}
}
}
});
tokio::run(
stream
.map_err(|err| panic!("{:?}", err))
.for_each(|_| Ok(())),
);
}
}