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// Copyright 2020 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.
mod protocol;
use crate::codec::RequestResponseCodec;
use crate::{RequestId, EMPTY_QUEUE_SHRINK_THRESHOLD};
use libp2p_swarm::handler::{
ConnectionEvent, DialUpgradeError, FullyNegotiatedInbound, FullyNegotiatedOutbound,
ListenUpgradeError,
};
pub use protocol::{ProtocolSupport, RequestProtocol, ResponseProtocol};
use futures::{channel::oneshot, future::BoxFuture, prelude::*, stream::FuturesUnordered};
use instant::Instant;
use libp2p_core::upgrade::{NegotiationError, UpgradeError};
use libp2p_swarm::{
handler::{ConnectionHandler, ConnectionHandlerEvent, ConnectionHandlerUpgrErr, KeepAlive},
SubstreamProtocol,
};
use smallvec::SmallVec;
use std::{
collections::VecDeque,
fmt, io,
sync::{
atomic::{AtomicU64, Ordering},
Arc,
},
task::{Context, Poll},
time::Duration,
};
/// A connection handler of a `RequestResponse` protocol.
#[doc(hidden)]
pub struct RequestResponseHandler<TCodec>
where
TCodec: RequestResponseCodec,
{
/// The supported inbound protocols.
inbound_protocols: SmallVec<[TCodec::Protocol; 2]>,
/// The request/response message codec.
codec: TCodec,
/// The keep-alive timeout of idle connections. A connection is considered
/// idle if there are no outbound substreams.
keep_alive_timeout: Duration,
/// The timeout for inbound and outbound substreams (i.e. request
/// and response processing).
substream_timeout: Duration,
/// The current connection keep-alive.
keep_alive: KeepAlive,
/// A pending fatal error that results in the connection being closed.
pending_error: Option<ConnectionHandlerUpgrErr<io::Error>>,
/// Queue of events to emit in `poll()`.
pending_events: VecDeque<RequestResponseHandlerEvent<TCodec>>,
/// Outbound upgrades waiting to be emitted as an `OutboundSubstreamRequest`.
outbound: VecDeque<RequestProtocol<TCodec>>,
/// Inbound upgrades waiting for the incoming request.
inbound: FuturesUnordered<
BoxFuture<
'static,
Result<
(
(RequestId, TCodec::Request),
oneshot::Sender<TCodec::Response>,
),
oneshot::Canceled,
>,
>,
>,
inbound_request_id: Arc<AtomicU64>,
}
impl<TCodec> RequestResponseHandler<TCodec>
where
TCodec: RequestResponseCodec + Send + Clone + 'static,
{
pub(super) fn new(
inbound_protocols: SmallVec<[TCodec::Protocol; 2]>,
codec: TCodec,
keep_alive_timeout: Duration,
substream_timeout: Duration,
inbound_request_id: Arc<AtomicU64>,
) -> Self {
Self {
inbound_protocols,
codec,
keep_alive: KeepAlive::Yes,
keep_alive_timeout,
substream_timeout,
outbound: VecDeque::new(),
inbound: FuturesUnordered::new(),
pending_events: VecDeque::new(),
pending_error: None,
inbound_request_id,
}
}
fn on_fully_negotiated_inbound(
&mut self,
FullyNegotiatedInbound {
protocol: sent,
info: request_id,
}: FullyNegotiatedInbound<
<Self as ConnectionHandler>::InboundProtocol,
<Self as ConnectionHandler>::InboundOpenInfo,
>,
) {
if sent {
self.pending_events
.push_back(RequestResponseHandlerEvent::ResponseSent(request_id))
} else {
self.pending_events
.push_back(RequestResponseHandlerEvent::ResponseOmission(request_id))
}
}
fn on_dial_upgrade_error(
&mut self,
DialUpgradeError { info, error }: DialUpgradeError<
<Self as ConnectionHandler>::OutboundOpenInfo,
<Self as ConnectionHandler>::OutboundProtocol,
>,
) {
match error {
ConnectionHandlerUpgrErr::Timeout => {
self.pending_events
.push_back(RequestResponseHandlerEvent::OutboundTimeout(info));
}
ConnectionHandlerUpgrErr::Upgrade(UpgradeError::Select(NegotiationError::Failed)) => {
// The remote merely doesn't support the protocol(s) we requested.
// This is no reason to close the connection, which may
// successfully communicate with other protocols already.
// An event is reported to permit user code to react to the fact that
// the remote peer does not support the requested protocol(s).
self.pending_events.push_back(
RequestResponseHandlerEvent::OutboundUnsupportedProtocols(info),
);
}
_ => {
// Anything else is considered a fatal error or misbehaviour of
// the remote peer and results in closing the connection.
self.pending_error = Some(error);
}
}
}
fn on_listen_upgrade_error(
&mut self,
ListenUpgradeError { info, error }: ListenUpgradeError<
<Self as ConnectionHandler>::InboundOpenInfo,
<Self as ConnectionHandler>::InboundProtocol,
>,
) {
match error {
ConnectionHandlerUpgrErr::Timeout => self
.pending_events
.push_back(RequestResponseHandlerEvent::InboundTimeout(info)),
ConnectionHandlerUpgrErr::Upgrade(UpgradeError::Select(NegotiationError::Failed)) => {
// The local peer merely doesn't support the protocol(s) requested.
// This is no reason to close the connection, which may
// successfully communicate with other protocols already.
// An event is reported to permit user code to react to the fact that
// the local peer does not support the requested protocol(s).
self.pending_events.push_back(
RequestResponseHandlerEvent::InboundUnsupportedProtocols(info),
);
}
_ => {
// Anything else is considered a fatal error or misbehaviour of
// the remote peer and results in closing the connection.
self.pending_error = Some(error);
}
}
}
}
/// The events emitted by the [`RequestResponseHandler`].
#[doc(hidden)]
pub enum RequestResponseHandlerEvent<TCodec>
where
TCodec: RequestResponseCodec,
{
/// A request has been received.
Request {
request_id: RequestId,
request: TCodec::Request,
sender: oneshot::Sender<TCodec::Response>,
},
/// A response has been received.
Response {
request_id: RequestId,
response: TCodec::Response,
},
/// A response to an inbound request has been sent.
ResponseSent(RequestId),
/// A response to an inbound request was omitted as a result
/// of dropping the response `sender` of an inbound `Request`.
ResponseOmission(RequestId),
/// An outbound request timed out while sending the request
/// or waiting for the response.
OutboundTimeout(RequestId),
/// An outbound request failed to negotiate a mutually supported protocol.
OutboundUnsupportedProtocols(RequestId),
/// An inbound request timed out while waiting for the request
/// or sending the response.
InboundTimeout(RequestId),
/// An inbound request failed to negotiate a mutually supported protocol.
InboundUnsupportedProtocols(RequestId),
}
impl<TCodec: RequestResponseCodec> fmt::Debug for RequestResponseHandlerEvent<TCodec> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
RequestResponseHandlerEvent::Request {
request_id,
request: _,
sender: _,
} => f
.debug_struct("RequestResponseHandlerEvent::Request")
.field("request_id", request_id)
.finish(),
RequestResponseHandlerEvent::Response {
request_id,
response: _,
} => f
.debug_struct("RequestResponseHandlerEvent::Response")
.field("request_id", request_id)
.finish(),
RequestResponseHandlerEvent::ResponseSent(request_id) => f
.debug_tuple("RequestResponseHandlerEvent::ResponseSent")
.field(request_id)
.finish(),
RequestResponseHandlerEvent::ResponseOmission(request_id) => f
.debug_tuple("RequestResponseHandlerEvent::ResponseOmission")
.field(request_id)
.finish(),
RequestResponseHandlerEvent::OutboundTimeout(request_id) => f
.debug_tuple("RequestResponseHandlerEvent::OutboundTimeout")
.field(request_id)
.finish(),
RequestResponseHandlerEvent::OutboundUnsupportedProtocols(request_id) => f
.debug_tuple("RequestResponseHandlerEvent::OutboundUnsupportedProtocols")
.field(request_id)
.finish(),
RequestResponseHandlerEvent::InboundTimeout(request_id) => f
.debug_tuple("RequestResponseHandlerEvent::InboundTimeout")
.field(request_id)
.finish(),
RequestResponseHandlerEvent::InboundUnsupportedProtocols(request_id) => f
.debug_tuple("RequestResponseHandlerEvent::InboundUnsupportedProtocols")
.field(request_id)
.finish(),
}
}
}
impl<TCodec> ConnectionHandler for RequestResponseHandler<TCodec>
where
TCodec: RequestResponseCodec + Send + Clone + 'static,
{
type InEvent = RequestProtocol<TCodec>;
type OutEvent = RequestResponseHandlerEvent<TCodec>;
type Error = ConnectionHandlerUpgrErr<io::Error>;
type InboundProtocol = ResponseProtocol<TCodec>;
type OutboundProtocol = RequestProtocol<TCodec>;
type OutboundOpenInfo = RequestId;
type InboundOpenInfo = RequestId;
fn listen_protocol(&self) -> SubstreamProtocol<Self::InboundProtocol, Self::InboundOpenInfo> {
// A channel for notifying the handler when the inbound
// upgrade received the request.
let (rq_send, rq_recv) = oneshot::channel();
// A channel for notifying the inbound upgrade when the
// response is sent.
let (rs_send, rs_recv) = oneshot::channel();
let request_id = RequestId(self.inbound_request_id.fetch_add(1, Ordering::Relaxed));
// By keeping all I/O inside the `ResponseProtocol` and thus the
// inbound substream upgrade via above channels, we ensure that it
// is all subject to the configured timeout without extra bookkeeping
// for inbound substreams as well as their timeouts and also make the
// implementation of inbound and outbound upgrades symmetric in
// this sense.
let proto = ResponseProtocol {
protocols: self.inbound_protocols.clone(),
codec: self.codec.clone(),
request_sender: rq_send,
response_receiver: rs_recv,
request_id,
};
// The handler waits for the request to come in. It then emits
// `RequestResponseHandlerEvent::Request` together with a
// `ResponseChannel`.
self.inbound
.push(rq_recv.map_ok(move |rq| (rq, rs_send)).boxed());
SubstreamProtocol::new(proto, request_id).with_timeout(self.substream_timeout)
}
fn on_behaviour_event(&mut self, request: Self::InEvent) {
self.keep_alive = KeepAlive::Yes;
self.outbound.push_back(request);
}
fn connection_keep_alive(&self) -> KeepAlive {
self.keep_alive
}
fn poll(
&mut self,
cx: &mut Context<'_>,
) -> Poll<ConnectionHandlerEvent<RequestProtocol<TCodec>, RequestId, Self::OutEvent, Self::Error>>
{
// Check for a pending (fatal) error.
if let Some(err) = self.pending_error.take() {
// The handler will not be polled again by the `Swarm`.
return Poll::Ready(ConnectionHandlerEvent::Close(err));
}
// Drain pending events.
if let Some(event) = self.pending_events.pop_front() {
return Poll::Ready(ConnectionHandlerEvent::Custom(event));
} else if self.pending_events.capacity() > EMPTY_QUEUE_SHRINK_THRESHOLD {
self.pending_events.shrink_to_fit();
}
// Check for inbound requests.
while let Poll::Ready(Some(result)) = self.inbound.poll_next_unpin(cx) {
match result {
Ok(((id, rq), rs_sender)) => {
// We received an inbound request.
self.keep_alive = KeepAlive::Yes;
return Poll::Ready(ConnectionHandlerEvent::Custom(
RequestResponseHandlerEvent::Request {
request_id: id,
request: rq,
sender: rs_sender,
},
));
}
Err(oneshot::Canceled) => {
// The inbound upgrade has errored or timed out reading
// or waiting for the request. The handler is informed
// via `inject_listen_upgrade_error`.
}
}
}
// Emit outbound requests.
if let Some(request) = self.outbound.pop_front() {
let info = request.request_id;
return Poll::Ready(ConnectionHandlerEvent::OutboundSubstreamRequest {
protocol: SubstreamProtocol::new(request, info)
.with_timeout(self.substream_timeout),
});
}
debug_assert!(self.outbound.is_empty());
if self.outbound.capacity() > EMPTY_QUEUE_SHRINK_THRESHOLD {
self.outbound.shrink_to_fit();
}
if self.inbound.is_empty() && self.keep_alive.is_yes() {
// No new inbound or outbound requests. However, we may just have
// started the latest inbound or outbound upgrade(s), so make sure
// the keep-alive timeout is preceded by the substream timeout.
let until = Instant::now() + self.substream_timeout + self.keep_alive_timeout;
self.keep_alive = KeepAlive::Until(until);
}
Poll::Pending
}
fn on_connection_event(
&mut self,
event: ConnectionEvent<
Self::InboundProtocol,
Self::OutboundProtocol,
Self::InboundOpenInfo,
Self::OutboundOpenInfo,
>,
) {
match event {
ConnectionEvent::FullyNegotiatedInbound(fully_negotiated_inbound) => {
self.on_fully_negotiated_inbound(fully_negotiated_inbound)
}
ConnectionEvent::FullyNegotiatedOutbound(FullyNegotiatedOutbound {
protocol: response,
info: request_id,
}) => {
self.pending_events
.push_back(RequestResponseHandlerEvent::Response {
request_id,
response,
});
}
ConnectionEvent::DialUpgradeError(dial_upgrade_error) => {
self.on_dial_upgrade_error(dial_upgrade_error)
}
ConnectionEvent::ListenUpgradeError(listen_upgrade_error) => {
self.on_listen_upgrade_error(listen_upgrade_error)
}
ConnectionEvent::AddressChange(_) => {}
}
}
}