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// Copyright 2023 litep2p developers
//
// 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.
//! WebRTC transport.
use crate::{
error::{AddressError, Error},
transport::{
manager::TransportHandle,
webrtc::{config::Config, connection::WebRtcConnection, opening::OpeningWebRtcConnection},
Endpoint, Transport, TransportBuilder, TransportEvent,
},
types::ConnectionId,
PeerId,
};
use futures::{future::BoxFuture, Future, Stream};
use futures_timer::Delay;
use multiaddr::{multihash::Multihash, Multiaddr, Protocol};
use socket2::{Domain, Socket, Type};
use str0m::{
change::{DtlsCert, IceCreds},
channel::{ChannelConfig, ChannelId},
net::{DatagramRecv, Protocol as Str0mProtocol, Receive},
Candidate, Input, Rtc,
};
use tokio::{
io::ReadBuf,
net::UdpSocket,
sync::mpsc::{channel, error::TrySendError, Sender},
};
use std::{
collections::{HashMap, VecDeque},
net::{IpAddr, SocketAddr},
pin::Pin,
sync::Arc,
task::{Context, Poll},
time::{Duration, Instant},
};
pub(crate) use substream::Substream;
mod connection;
mod opening;
mod substream;
mod util;
pub mod config;
pub(super) mod schema {
pub(super) mod webrtc {
include!(concat!(env!("OUT_DIR"), "/webrtc.rs"));
}
pub(super) mod noise {
include!(concat!(env!("OUT_DIR"), "/noise.rs"));
}
}
/// Logging target for the file.
const LOG_TARGET: &str = "litep2p::webrtc";
/// Hardcoded remote fingerprint.
const REMOTE_FINGERPRINT: &str =
"sha-256 FF:FF:FF:FF:FF:FF:FF:FF:FF:FF:FF:FF:FF:FF:FF:FF:FF:FF:FF:FF:FF:FF:FF:FF:FF:FF:FF:FF:FF:FF:FF:FF";
/// Connection context.
struct ConnectionContext {
/// Remote peer ID.
peer: PeerId,
/// Connection ID.
connection_id: ConnectionId,
/// TX channel for sending datagrams to the connection event loop.
tx: Sender<Vec<u8>>,
}
/// Events received from opening connections that are handled
/// by the [`WebRtcTransport`] event loop.
enum ConnectionEvent {
/// Connection established.
ConnectionEstablished {
/// Remote peer ID.
peer: PeerId,
/// Endpoint.
endpoint: Endpoint,
},
/// Connection to peer closed.
ConnectionClosed,
/// Timeout.
Timeout {
/// Timeout duration.
duration: Duration,
},
}
/// WebRTC transport.
pub(crate) struct WebRtcTransport {
/// Transport context.
context: TransportHandle,
/// UDP socket.
socket: Arc<UdpSocket>,
/// DTLS certificate.
dtls_cert: DtlsCert,
/// Assigned listen addresss.
listen_address: SocketAddr,
/// Datagram buffer size.
datagram_buffer_size: usize,
/// Connected peers.
open: HashMap<SocketAddr, ConnectionContext>,
/// OpeningWebRtc connections.
opening: HashMap<SocketAddr, OpeningWebRtcConnection>,
/// `ConnectionId -> SocketAddr` mappings.
connections: HashMap<ConnectionId, (PeerId, SocketAddr, Endpoint)>,
/// Pending timeouts.
timeouts: HashMap<SocketAddr, BoxFuture<'static, ()>>,
/// Pending events.
pending_events: VecDeque<TransportEvent>,
}
impl WebRtcTransport {
/// Extract socket address and `PeerId`, if found, from `address`.
fn get_socket_address(address: &Multiaddr) -> crate::Result<(SocketAddr, Option<PeerId>)> {
tracing::trace!(target: LOG_TARGET, ?address, "parse multi address");
let mut iter = address.iter();
let socket_address = match iter.next() {
Some(Protocol::Ip6(address)) => match iter.next() {
Some(Protocol::Udp(port)) => SocketAddr::new(IpAddr::V6(address), port),
protocol => {
tracing::error!(
target: LOG_TARGET,
?protocol,
"invalid transport protocol, expected `Upd`",
);
return Err(Error::AddressError(AddressError::InvalidProtocol));
}
},
Some(Protocol::Ip4(address)) => match iter.next() {
Some(Protocol::Udp(port)) => SocketAddr::new(IpAddr::V4(address), port),
protocol => {
tracing::error!(
target: LOG_TARGET,
?protocol,
"invalid transport protocol, expected `Udp`",
);
return Err(Error::AddressError(AddressError::InvalidProtocol));
}
},
protocol => {
tracing::error!(target: LOG_TARGET, ?protocol, "invalid transport protocol");
return Err(Error::AddressError(AddressError::InvalidProtocol));
}
};
match iter.next() {
Some(Protocol::WebRTC) => {}
protocol => {
tracing::error!(
target: LOG_TARGET,
?protocol,
"invalid protocol, expected `WebRTC`"
);
return Err(Error::AddressError(AddressError::InvalidProtocol));
}
}
let maybe_peer = match iter.next() {
Some(Protocol::P2p(multihash)) => Some(PeerId::from_multihash(multihash)?),
None => None,
protocol => {
tracing::error!(
target: LOG_TARGET,
?protocol,
"invalid protocol, expected `P2p` or `None`"
);
return Err(Error::AddressError(AddressError::InvalidProtocol));
}
};
Ok((socket_address, maybe_peer))
}
/// Create RTC client and open channel for Noise handshake.
fn make_rtc_client(
&self,
ufrag: &str,
pass: &str,
source: SocketAddr,
destination: SocketAddr,
) -> (Rtc, ChannelId) {
let mut rtc = Rtc::builder()
.set_ice_lite(true)
.set_dtls_cert(self.dtls_cert.clone())
.set_fingerprint_verification(false)
.build();
rtc.add_local_candidate(Candidate::host(destination, Str0mProtocol::Udp).unwrap());
rtc.add_remote_candidate(Candidate::host(source, Str0mProtocol::Udp).unwrap());
rtc.direct_api()
.set_remote_fingerprint(REMOTE_FINGERPRINT.parse().expect("parse() to succeed"));
rtc.direct_api().set_remote_ice_credentials(IceCreds {
ufrag: ufrag.to_owned(),
pass: pass.to_owned(),
});
rtc.direct_api().set_local_ice_credentials(IceCreds {
ufrag: ufrag.to_owned(),
pass: pass.to_owned(),
});
rtc.direct_api().set_ice_controlling(false);
rtc.direct_api().start_dtls(false).unwrap();
rtc.direct_api().start_sctp(false);
let noise_channel_id = rtc.direct_api().create_data_channel(ChannelConfig {
label: "noise".to_string(),
ordered: false,
reliability: Default::default(),
negotiated: Some(0),
protocol: "".to_string(),
});
(rtc, noise_channel_id)
}
/// Poll opening connection.
fn poll_connection(&mut self, source: &SocketAddr) -> ConnectionEvent {
let Some(connection) = self.opening.get_mut(source) else {
tracing::warn!(
target: LOG_TARGET,
?source,
"connection doesn't exist",
);
return ConnectionEvent::ConnectionClosed;
};
loop {
match connection.poll_process() {
opening::WebRtcEvent::Timeout { timeout } => {
let duration = timeout - Instant::now();
match duration.is_zero() {
true => match connection.on_timeout() {
Ok(()) => continue,
Err(error) => {
tracing::debug!(
target: LOG_TARGET,
?source,
?error,
"failed to handle timeout",
);
return ConnectionEvent::ConnectionClosed;
}
},
false => return ConnectionEvent::Timeout { duration },
}
}
opening::WebRtcEvent::Transmit {
destination,
datagram,
} =>
if let Err(error) = self.socket.try_send_to(&datagram, destination) {
tracing::warn!(
target: LOG_TARGET,
?source,
?error,
"failed to send datagram",
);
},
opening::WebRtcEvent::ConnectionClosed => return ConnectionEvent::ConnectionClosed,
opening::WebRtcEvent::ConnectionOpened { peer, endpoint } => {
return ConnectionEvent::ConnectionEstablished { peer, endpoint };
}
}
}
}
/// Handle socket input.
///
/// If the datagram was received from an active client, it's dispatched to the connection
/// handler, if there is space in the queue. If the datagram opened a new connection or it
/// belonged to a client who is opening, the event loop is instructed to poll the client
/// until it timeouts.
///
/// Returns `true` if the client should be polled.
fn on_socket_input(&mut self, source: SocketAddr, buffer: Vec<u8>) -> crate::Result<bool> {
if let Some(ConnectionContext {
peer,
connection_id,
tx,
}) = self.open.get_mut(&source)
{
match tx.try_send(buffer) {
Ok(_) => return Ok(false),
Err(TrySendError::Full(_)) => {
tracing::warn!(
target: LOG_TARGET,
?source,
?peer,
?connection_id,
"channel full, dropping datagram",
);
return Ok(false);
}
Err(TrySendError::Closed(_)) => return Ok(false),
}
}
// if the peer doesn't exist, decode the message and expect to receive `Stun`
// so that a new connection can be initialized
let contents: DatagramRecv =
buffer.as_slice().try_into().map_err(|_| Error::InvalidData)?;
match contents {
DatagramRecv::Stun(message) if !self.opening.contains_key(&source) => {
if let Some((ufrag, pass)) = message.split_username() {
tracing::debug!(
target: LOG_TARGET,
?source,
?ufrag,
?pass,
"received stun message"
);
// create new `Rtc` object for the peer and give it the received STUN message
let (mut rtc, noise_channel_id) = self.make_rtc_client(
ufrag,
pass,
source,
self.socket.local_addr().unwrap(),
);
rtc.handle_input(Input::Receive(
Instant::now(),
Receive {
source,
proto: Str0mProtocol::Udp,
destination: self.socket.local_addr().unwrap(),
contents: DatagramRecv::Stun(message.clone()),
},
))
.expect("client to handle input successfully");
let connection_id = self.context.next_connection_id();
let connection = OpeningWebRtcConnection::new(
rtc,
connection_id,
noise_channel_id,
self.context.keypair.clone(),
source,
self.listen_address,
);
self.opening.insert(source, connection);
}
}
msg => {
if let Err(error) = self.opening.get_mut(&source).expect("to exist").on_input(msg) {
tracing::error!(
target: LOG_TARGET,
?error,
?source,
"failed to handle inbound datagram"
);
}
}
}
Ok(true)
}
}
impl TransportBuilder for WebRtcTransport {
type Config = Config;
type Transport = WebRtcTransport;
/// Create new [`Transport`] object.
fn new(context: TransportHandle, config: Self::Config) -> crate::Result<(Self, Vec<Multiaddr>)>
where
Self: Sized,
{
tracing::info!(
target: LOG_TARGET,
listen_addresses = ?config.listen_addresses,
"start webrtc transport",
);
let (listen_address, _) = Self::get_socket_address(&config.listen_addresses[0])?;
let socket = match listen_address.is_ipv4() {
true => {
let socket = Socket::new(Domain::IPV4, Type::DGRAM, Some(socket2::Protocol::UDP))?;
socket.bind(&listen_address.into())?;
socket
}
false => {
let socket = Socket::new(Domain::IPV6, Type::DGRAM, Some(socket2::Protocol::UDP))?;
socket.set_only_v6(true)?;
socket.bind(&listen_address.into())?;
socket
}
};
socket.set_reuse_address(true)?;
socket.set_nonblocking(true)?;
#[cfg(unix)]
socket.set_reuse_port(true)?;
let socket = UdpSocket::from_std(socket.into())?;
let listen_address = socket.local_addr()?;
let dtls_cert = DtlsCert::new();
let listen_multi_addresses = {
let fingerprint = dtls_cert.fingerprint().bytes;
const MULTIHASH_SHA256_CODE: u64 = 0x12;
let certificate = Multihash::wrap(MULTIHASH_SHA256_CODE, &fingerprint)
.expect("fingerprint's len to be 32 bytes");
vec![Multiaddr::empty()
.with(Protocol::from(listen_address.ip()))
.with(Protocol::Udp(listen_address.port()))
.with(Protocol::WebRTC)
.with(Protocol::Certhash(certificate))]
};
Ok((
Self {
context,
dtls_cert,
listen_address,
open: HashMap::new(),
opening: HashMap::new(),
connections: HashMap::new(),
socket: Arc::new(socket),
timeouts: HashMap::new(),
pending_events: VecDeque::new(),
datagram_buffer_size: config.datagram_buffer_size,
},
listen_multi_addresses,
))
}
}
impl Transport for WebRtcTransport {
fn dial(&mut self, connection_id: ConnectionId, address: Multiaddr) -> crate::Result<()> {
tracing::warn!(
target: LOG_TARGET,
?connection_id,
?address,
"webrtc cannot dial",
);
Err(Error::NotSupported("webrtc cannot dial peers".to_string()))
}
fn accept(&mut self, connection_id: ConnectionId) -> crate::Result<()> {
tracing::trace!(
target: LOG_TARGET,
?connection_id,
"inbound connection accepted",
);
let (peer, source, endpoint) =
self.connections.remove(&connection_id).ok_or_else(|| {
tracing::warn!(
target: LOG_TARGET,
?connection_id,
"pending connection doens't exist",
);
Error::InvalidState
})?;
let connection = self.opening.remove(&source).ok_or_else(|| {
tracing::warn!(
target: LOG_TARGET,
?connection_id,
"pending connection doens't exist",
);
Error::InvalidState
})?;
let rtc = connection.on_accept()?;
let (tx, rx) = channel(self.datagram_buffer_size);
let protocol_set = self.context.protocol_set(connection_id);
let connection_id = endpoint.connection_id();
let connection = WebRtcConnection::new(
rtc,
peer,
source,
self.listen_address,
Arc::clone(&self.socket),
protocol_set,
endpoint,
rx,
);
self.open.insert(
source,
ConnectionContext {
tx,
peer,
connection_id,
},
);
self.context.executor.run(Box::pin(async move {
connection.run().await;
}));
Ok(())
}
fn reject(&mut self, connection_id: ConnectionId) -> crate::Result<()> {
tracing::trace!(
target: LOG_TARGET,
?connection_id,
"inbound connection rejected",
);
let (_, source, _) = self.connections.remove(&connection_id).ok_or_else(|| {
tracing::warn!(
target: LOG_TARGET,
?connection_id,
"pending connection doens't exist",
);
Error::InvalidState
})?;
self.opening
.remove(&source)
.ok_or_else(|| {
tracing::warn!(
target: LOG_TARGET,
?connection_id,
"pending connection doens't exist",
);
Error::InvalidState
})
.map(|_| ())
}
fn open(
&mut self,
_connection_id: ConnectionId,
_addresses: Vec<Multiaddr>,
) -> crate::Result<()> {
Ok(())
}
fn negotiate(&mut self, _connection_id: ConnectionId) -> crate::Result<()> {
Ok(())
}
fn cancel(&mut self, _connection_id: ConnectionId) {}
}
impl Stream for WebRtcTransport {
type Item = TransportEvent;
fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
let this = Pin::into_inner(self);
if let Some(event) = this.pending_events.pop_front() {
return Poll::Ready(Some(event));
}
loop {
let mut buf = vec![0u8; 16384];
let mut read_buf = ReadBuf::new(&mut buf);
match this.socket.poll_recv_from(cx, &mut read_buf) {
Poll::Pending => break,
Poll::Ready(Err(error)) => {
tracing::info!(
target: LOG_TARGET,
?error,
"webrtc udp socket closed",
);
return Poll::Ready(None);
}
Poll::Ready(Ok(source)) => {
let nread = read_buf.filled().len();
buf.truncate(nread);
match this.on_socket_input(source, buf) {
Ok(false) => {}
Ok(true) => loop {
match this.poll_connection(&source) {
ConnectionEvent::ConnectionEstablished { peer, endpoint } => {
this.connections.insert(
endpoint.connection_id(),
(peer, source, endpoint.clone()),
);
// keep polling the connection until it registers a timeout
this.pending_events.push_back(
TransportEvent::ConnectionEstablished { peer, endpoint },
);
}
ConnectionEvent::ConnectionClosed => {
this.opening.remove(&source);
this.timeouts.remove(&source);
break;
}
ConnectionEvent::Timeout { duration } => {
this.timeouts.insert(
source,
Box::pin(async move { Delay::new(duration).await }),
);
break;
}
}
},
Err(error) => {
tracing::debug!(
target: LOG_TARGET,
?source,
?error,
"failed to handle datagram",
);
}
}
}
}
}
// go over all pending timeouts to see if any of them have expired
// and if any of them have, poll the connection until it registers another timeout
let pending_events = this
.timeouts
.iter_mut()
.filter_map(|(source, mut delay)| match Pin::new(&mut delay).poll(cx) {
Poll::Pending => None,
Poll::Ready(_) => Some(*source),
})
.collect::<Vec<_>>()
.into_iter()
.filter_map(|source| {
let mut pending_event = None;
loop {
match this.poll_connection(&source) {
ConnectionEvent::ConnectionEstablished { peer, endpoint } => {
this.connections
.insert(endpoint.connection_id(), (peer, source, endpoint.clone()));
// keep polling the connection until it registers a timeout
pending_event =
Some(TransportEvent::ConnectionEstablished { peer, endpoint });
}
ConnectionEvent::ConnectionClosed => {
this.opening.remove(&source);
return None;
}
ConnectionEvent::Timeout { duration } => {
this.timeouts.insert(
source,
Box::pin(async move {
Delay::new(duration);
}),
);
break;
}
}
}
pending_event
})
.collect::<VecDeque<_>>();
this.timeouts.retain(|source, _| this.opening.contains_key(source));
this.pending_events.extend(pending_events);
this.pending_events
.pop_front()
.map_or(Poll::Pending, |event| Poll::Ready(Some(event)))
}
}