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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 std::marker::PhantomData;
use futures::{channel::oneshot, StreamExt};
use codec::{Decode, Encode};
use sc_network::{config as netconfig, NetworkBackend};
use sc_network_types::PeerId;
use sp_runtime::traits::Block;
use super::{IsRequest, ReqProtocolNames};
use crate::UnifiedReputationChange;
mod error;
pub use error::{Error, FatalError, JfyiError, Result};
/// A request coming in, including a sender for sending responses.
///
/// Typed `IncomingRequest`s, see `IncomingRequest::get_config_receiver` and substrate
/// `NetworkConfiguration` for more information.
#[derive(Debug)]
pub struct IncomingRequest<Req> {
/// `PeerId` of sending peer.
pub peer: PeerId,
/// The sent request.
pub payload: Req,
/// Sender for sending response back.
pub pending_response: OutgoingResponseSender<Req>,
}
impl<Req> IncomingRequest<Req>
where
Req: IsRequest + Decode + Encode,
Req::Response: Encode,
{
/// Create configuration for `NetworkConfiguration::request_response_protocols` and a
/// corresponding typed receiver.
///
/// This Register that config with substrate networking and receive incoming requests via the
/// returned `IncomingRequestReceiver`.
pub fn get_config_receiver<B: Block, N: NetworkBackend<B, <B as Block>::Hash>>(
req_protocol_names: &ReqProtocolNames,
) -> (IncomingRequestReceiver<Req>, N::RequestResponseProtocolConfig) {
let (raw, cfg) = Req::PROTOCOL.get_config::<B, N>(req_protocol_names);
(IncomingRequestReceiver { raw, phantom: PhantomData {} }, cfg)
}
/// Create new `IncomingRequest`.
pub fn new(
peer: PeerId,
payload: Req,
pending_response: oneshot::Sender<netconfig::OutgoingResponse>,
) -> Self {
Self {
peer,
payload,
pending_response: OutgoingResponseSender { pending_response, phantom: PhantomData {} },
}
}
/// Try building from raw substrate request.
///
/// This function will fail if the request cannot be decoded and will apply passed in
/// reputation changes in that case.
///
/// Params:
/// - The raw request to decode
/// - Reputation changes to apply for the peer in case decoding fails.
fn try_from_raw(
raw: sc_network::config::IncomingRequest,
reputation_changes: Vec<UnifiedReputationChange>,
) -> std::result::Result<Self, JfyiError> {
let sc_network::config::IncomingRequest { payload, peer, pending_response } = raw;
let payload = match Req::decode(&mut payload.as_ref()) {
Ok(payload) => payload,
Err(err) => {
let reputation_changes = reputation_changes.into_iter().map(|r| r.into()).collect();
let response = sc_network::config::OutgoingResponse {
result: Err(()),
reputation_changes,
sent_feedback: None,
};
if let Err(_) = pending_response.send(response) {
return Err(JfyiError::DecodingErrorNoReputationChange(peer, err))
}
return Err(JfyiError::DecodingError(peer, err))
},
};
Ok(Self::new(peer, payload, pending_response))
}
/// Convert into raw untyped substrate `IncomingRequest`.
///
/// This is mostly useful for testing.
pub fn into_raw(self) -> sc_network::config::IncomingRequest {
sc_network::config::IncomingRequest {
peer: self.peer,
payload: self.payload.encode(),
pending_response: self.pending_response.pending_response,
}
}
/// Send the response back.
///
/// Calls [`OutgoingResponseSender::send_response`].
pub fn send_response(self, resp: Req::Response) -> std::result::Result<(), Req::Response> {
self.pending_response.send_response(resp)
}
/// Send response with additional options.
///
/// Calls [`OutgoingResponseSender::send_outgoing_response`].
pub fn send_outgoing_response(
self,
resp: OutgoingResponse<<Req as IsRequest>::Response>,
) -> std::result::Result<(), ()> {
self.pending_response.send_outgoing_response(resp)
}
}
/// Sender for sending back responses on an `IncomingRequest`.
#[derive(Debug)]
pub struct OutgoingResponseSender<Req> {
pending_response: oneshot::Sender<netconfig::OutgoingResponse>,
phantom: PhantomData<Req>,
}
impl<Req> OutgoingResponseSender<Req>
where
Req: IsRequest + Decode,
Req::Response: Encode,
{
/// Send the response back.
///
/// On success we return `Ok(())`, on error we return the not sent `Response`.
///
/// `netconfig::OutgoingResponse` exposes a way of modifying the peer's reputation. If needed we
/// can change this function to expose this feature as well.
pub fn send_response(self, resp: Req::Response) -> std::result::Result<(), Req::Response> {
self.pending_response
.send(netconfig::OutgoingResponse {
result: Ok(resp.encode()),
reputation_changes: Vec::new(),
sent_feedback: None,
})
.map_err(|_| resp)
}
/// Send response with additional options.
///
/// This variant allows for waiting for the response to be sent out, allows for changing peer's
/// reputation and allows for not sending a response at all (for only changing the peer's
/// reputation).
pub fn send_outgoing_response(
self,
resp: OutgoingResponse<<Req as IsRequest>::Response>,
) -> std::result::Result<(), ()> {
let OutgoingResponse { result, reputation_changes, sent_feedback } = resp;
let response = netconfig::OutgoingResponse {
result: result.map(|v| v.encode()),
reputation_changes: reputation_changes.into_iter().map(|c| c.into()).collect(),
sent_feedback,
};
self.pending_response.send(response).map_err(|_| ())
}
}
/// Typed variant of [`netconfig::OutgoingResponse`].
///
/// Responses to `IncomingRequest`s.
pub struct OutgoingResponse<Response> {
/// The payload of the response.
///
/// `Err(())` if none is available e.g. due to an error while handling the request.
pub result: std::result::Result<Response, ()>,
/// Reputation changes accrued while handling the request. To be applied to the reputation of
/// the peer sending the request.
pub reputation_changes: Vec<UnifiedReputationChange>,
/// If provided, the `oneshot::Sender` will be notified when the request has been sent to the
/// peer.
pub sent_feedback: Option<oneshot::Sender<()>>,
}
/// Receiver for incoming requests.
///
/// Takes care of decoding and handling of invalid encoded requests.
pub struct IncomingRequestReceiver<Req> {
raw: async_channel::Receiver<netconfig::IncomingRequest>,
phantom: PhantomData<Req>,
}
impl<Req> IncomingRequestReceiver<Req>
where
Req: IsRequest + Decode + Encode,
Req::Response: Encode,
{
/// Try to receive the next incoming request.
///
/// Any received request will be decoded, on decoding errors the provided reputation changes
/// will be applied and an error will be reported.
pub async fn recv<F>(&mut self, reputation_changes: F) -> Result<IncomingRequest<Req>>
where
F: FnOnce() -> Vec<UnifiedReputationChange>,
{
let req = match self.raw.next().await {
None => return Err(FatalError::RequestChannelExhausted.into()),
Some(raw) => IncomingRequest::<Req>::try_from_raw(raw, reputation_changes())?,
};
Ok(req)
}
}