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// Copyright (C) Parity Technologies (UK) Ltd.
// This file is part of Polkadot.
// Polkadot is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// Polkadot is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with Polkadot. If not, see <http://www.gnu.org/licenses/>.
use futures::{channel::oneshot, prelude::Future, FutureExt};
use codec::{Decode, Encode, Error as DecodingError};
use network::ProtocolName;
use sc_network as network;
use sc_network_types::PeerId;
use polkadot_primitives::AuthorityDiscoveryId;
use super::{v1, v2, IsRequest, Protocol};
/// All requests that can be sent to the network bridge via `NetworkBridgeTxMessage::SendRequest`.
#[derive(Debug)]
pub enum Requests {
/// Request an availability chunk from a node.
ChunkFetching(OutgoingRequest<v2::ChunkFetchingRequest, v1::ChunkFetchingRequest>),
/// Fetch a collation from a collator which previously announced it.
CollationFetchingV1(OutgoingRequest<v1::CollationFetchingRequest>),
/// Fetch a PoV from a validator which previously sent out a seconded statement.
PoVFetchingV1(OutgoingRequest<v1::PoVFetchingRequest>),
/// Request full available data from a node.
AvailableDataFetchingV1(OutgoingRequest<v1::AvailableDataFetchingRequest>),
/// Requests for fetching large statements as part of statement distribution.
StatementFetchingV1(OutgoingRequest<v1::StatementFetchingRequest>),
/// Requests for notifying about an ongoing dispute.
DisputeSendingV1(OutgoingRequest<v1::DisputeRequest>),
/// Request a candidate and attestations.
AttestedCandidateV2(OutgoingRequest<v2::AttestedCandidateRequest>),
/// Fetch a collation from a collator which previously announced it.
/// Compared to V1 it requires specifying which candidate is requested by its hash.
CollationFetchingV2(OutgoingRequest<v2::CollationFetchingRequest>),
}
impl Requests {
/// Encode the request.
///
/// The corresponding protocol is returned as well, as we are now leaving typed territory.
///
/// Note: `Requests` is just an enum collecting all supported requests supported by network
/// bridge, it is never sent over the wire. This function just encodes the individual requests
/// contained in the `enum`.
pub fn encode_request(self) -> (Protocol, OutgoingRequest<Vec<u8>>) {
match self {
Self::ChunkFetching(r) => r.encode_request(),
Self::CollationFetchingV1(r) => r.encode_request(),
Self::CollationFetchingV2(r) => r.encode_request(),
Self::PoVFetchingV1(r) => r.encode_request(),
Self::AvailableDataFetchingV1(r) => r.encode_request(),
Self::StatementFetchingV1(r) => r.encode_request(),
Self::DisputeSendingV1(r) => r.encode_request(),
Self::AttestedCandidateV2(r) => r.encode_request(),
}
}
}
/// Used by the network to send us a response to a request.
pub type ResponseSender = oneshot::Sender<Result<(Vec<u8>, ProtocolName), network::RequestFailure>>;
/// Any error that can occur when sending a request.
#[derive(Debug, thiserror::Error)]
pub enum RequestError {
/// Response could not be decoded.
#[error("Response could not be decoded: {0}")]
InvalidResponse(#[from] DecodingError),
/// Some error in substrate/libp2p happened.
#[error("{0}")]
NetworkError(#[from] network::RequestFailure),
/// Response got canceled by networking.
#[error("Response channel got canceled")]
Canceled(#[from] oneshot::Canceled),
}
impl RequestError {
/// Whether the error represents some kind of timeout condition.
pub fn is_timed_out(&self) -> bool {
match self {
Self::Canceled(_) |
Self::NetworkError(network::RequestFailure::Obsolete) |
Self::NetworkError(network::RequestFailure::Network(
network::OutboundFailure::Timeout,
)) => true,
_ => false,
}
}
}
/// A request to be sent to the network bridge, including a sender for sending responses/failures.
///
/// The network implementation will make use of that sender for informing the requesting subsystem
/// about responses/errors.
///
/// When using `Recipient::Peer`, keep in mind that no address (as in IP address and port) might
/// be known for that specific peer. You are encouraged to use `Peer` for peers that you are
/// expected to be already connected to.
/// When using `Recipient::Authority`, the addresses can be found thanks to the authority
/// discovery system.
#[derive(Debug)]
pub struct OutgoingRequest<Req, FallbackReq = Req> {
/// Intended recipient of this request.
pub peer: Recipient,
/// The actual request to send over the wire.
pub payload: Req,
/// Optional fallback request and protocol.
pub fallback_request: Option<(FallbackReq, Protocol)>,
/// Sender which is used by networking to get us back a response.
pub pending_response: ResponseSender,
}
/// Potential recipients of an outgoing request.
#[derive(Debug, Eq, Hash, PartialEq, Clone)]
pub enum Recipient {
/// Recipient is a regular peer and we know its peer id.
Peer(PeerId),
/// Recipient is a validator, we address it via this `AuthorityDiscoveryId`.
Authority(AuthorityDiscoveryId),
}
/// Responses received for an `OutgoingRequest`.
pub type OutgoingResult<Res> = Result<Res, RequestError>;
impl<Req, FallbackReq> OutgoingRequest<Req, FallbackReq>
where
Req: IsRequest + Encode,
Req::Response: Decode,
FallbackReq: IsRequest + Encode,
FallbackReq::Response: Decode,
{
/// Create a new `OutgoingRequest`.
///
/// It will contain a sender that is used by the networking for sending back responses. The
/// connected receiver is returned as the second element in the returned tuple.
pub fn new(
peer: Recipient,
payload: Req,
) -> (Self, impl Future<Output = OutgoingResult<Req::Response>>) {
let (tx, rx) = oneshot::channel();
let r = Self { peer, payload, pending_response: tx, fallback_request: None };
(r, receive_response::<Req>(rx.map(|r| r.map(|r| r.map(|(resp, _)| resp)))))
}
/// Create a new `OutgoingRequest` with a fallback in case the remote does not support this
/// protocol. Useful when adding a new version of a req-response protocol, to achieve
/// compatibility with the older version.
///
/// Returns a raw `Vec<u8>` response over the channel. Use the associated `ProtocolName` to know
/// which request was the successful one and appropriately decode the response.
pub fn new_with_fallback(
peer: Recipient,
payload: Req,
fallback_request: FallbackReq,
) -> (Self, impl Future<Output = OutgoingResult<(Vec<u8>, ProtocolName)>>) {
let (tx, rx) = oneshot::channel();
let r = Self {
peer,
payload,
pending_response: tx,
fallback_request: Some((fallback_request, FallbackReq::PROTOCOL)),
};
(r, async { Ok(rx.await??) })
}
/// Encode a request into a `Vec<u8>`.
///
/// As this throws away type information, we also return the `Protocol` this encoded request
/// adheres to.
pub fn encode_request(self) -> (Protocol, OutgoingRequest<Vec<u8>>) {
let OutgoingRequest { peer, payload, pending_response, fallback_request } = self;
let encoded = OutgoingRequest {
peer,
payload: payload.encode(),
fallback_request: fallback_request.map(|(r, p)| (r.encode(), p)),
pending_response,
};
(Req::PROTOCOL, encoded)
}
}
/// Future for actually receiving a typed response for an `OutgoingRequest`.
async fn receive_response<Req>(
rec: impl Future<Output = Result<Result<Vec<u8>, network::RequestFailure>, oneshot::Canceled>>,
) -> OutgoingResult<Req::Response>
where
Req: IsRequest,
Req::Response: Decode,
{
let raw = rec.await??;
Ok(Decode::decode(&mut raw.as_ref())?)
}