Add a PeriodicIdentification protocol handler (#579)

* Add ProtocolsHandler trait

* Reexport symbols

* Add a note about shutting down

* Add a PeriodicIdentification protocol handler

protocols/identify/src/lib.rs

@@ -81,8 +81,10 @@ extern crate tokio_timer;
 extern crate unsigned_varint;
 extern crate void;
 
+pub use self::periodic_id_handler::{PeriodicIdentification, PeriodicIdentificationEvent};
 pub use self::protocol::{IdentifyInfo, IdentifyOutput};
 pub use self::protocol::{IdentifyProtocolConfig, IdentifySender};
 
+mod periodic_id_handler;
 mod protocol;
 mod structs_proto;

protocols/identify/src/periodic_id_handler.rs

@@ -0,0 +1,180 @@
+// 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 futures::prelude::*;
+use libp2p_core::nodes::handled_node::NodeHandlerEndpoint;
+use libp2p_core::nodes::protocols_handler::{ProtocolsHandler, ProtocolsHandlerEvent};
+use libp2p_core::upgrade::{self, toggleable::Toggleable};
+use libp2p_core::{ConnectionUpgrade, Multiaddr};
+use std::io;
+use std::marker::PhantomData;
+use std::time::{Duration, Instant};
+use tokio_io::{AsyncRead, AsyncWrite};
+use tokio_timer::Delay;
+use void::Void;
+use {IdentifyInfo, IdentifyOutput, IdentifyProtocolConfig};
+
+/// Delay between the moment we connect and the first time we identify.
+const DELAY_TO_FIRST_ID: Duration = Duration::from_millis(500);
+/// After an identification succeeded, wait this long before the next time.
+const DELAY_TO_NEXT_ID: Duration = Duration::from_secs(5 * 60);
+/// After we failed to identify the remote, try again after the given delay.
+const TRY_AGAIN_ON_ERR: Duration = Duration::from_secs(60 * 60);
+
+/// Protocol handler that identifies the remote at a regular period.
+pub struct PeriodicIdentification<TSubstream> {
+    /// Configuration for the protocol.
+    config: Toggleable<IdentifyProtocolConfig>,
+
+    /// If `Some`, we successfully generated an `PeriodicIdentificationEvent` and we will produce
+    /// it the next time `poll()` is invoked.
+    pending_result: Option<PeriodicIdentificationEvent>,
+
+    /// Future that fires when we need to identify the node again. If `None`, means that we should
+    /// shut down.
+    next_id: Option<Delay>,
+
+    /// Marker for strong typing.
+    marker: PhantomData<TSubstream>,
+}
+
+/// Event produced by the periodic identifier.
+#[derive(Debug)]
+pub enum PeriodicIdentificationEvent {
+    /// We obtained identification information from the remote
+    Identified {
+        /// Information of the remote.
+        info: IdentifyInfo,
+        /// Address the remote observes us as.
+        observed_addr: Multiaddr,
+    },
+
+    /// Failed to identify the remote.
+    IdentificationError(io::Error),
+}
+
+impl<TSubstream> PeriodicIdentification<TSubstream> {
+    /// Builds a new `PeriodicIdentification`.
+    #[inline]
+    pub fn new() -> Self {
+        PeriodicIdentification {
+            config: upgrade::toggleable(IdentifyProtocolConfig),
+            pending_result: None,
+            next_id: Some(Delay::new(Instant::now() + DELAY_TO_FIRST_ID)),
+            marker: PhantomData,
+        }
+    }
+}
+
+impl<TSubstream> ProtocolsHandler for PeriodicIdentification<TSubstream>
+where
+    TSubstream: AsyncRead + AsyncWrite + Send + Sync + 'static, // TODO: remove useless bounds
+{
+    type InEvent = Void;
+    type OutEvent = PeriodicIdentificationEvent;
+    type Substream = TSubstream;
+    type Protocol = Toggleable<IdentifyProtocolConfig>;
+    type OutboundOpenInfo = ();
+
+    #[inline]
+    fn listen_protocol(&self) -> Self::Protocol {
+        let mut upgrade = self.config.clone();
+        upgrade.disable();
+        upgrade
+    }
+
+    fn inject_fully_negotiated(
+        &mut self,
+        protocol: <Self::Protocol as ConnectionUpgrade<TSubstream>>::Output,
+        _endpoint: NodeHandlerEndpoint<Self::OutboundOpenInfo>,
+    ) {
+        match protocol {
+            IdentifyOutput::RemoteInfo {
+                info,
+                observed_addr,
+            } => {
+                self.pending_result = Some(PeriodicIdentificationEvent::Identified {
+                    info,
+                    observed_addr,
+                });
+            }
+            IdentifyOutput::Sender { .. } => unreachable!(
+                "Sender can only be produced if we listen for the identify \
+                 protocol ; however we disable it in listen_protocol"
+            ),
+        }
+    }
+
+    #[inline]
+    fn inject_event(&mut self, _: &Self::InEvent) {}
+
+    #[inline]
+    fn inject_inbound_closed(&mut self) {}
+
+    #[inline]
+    fn inject_dial_upgrade_error(&mut self, _: Self::OutboundOpenInfo, err: io::Error) {
+        self.pending_result = Some(PeriodicIdentificationEvent::IdentificationError(err));
+        if let Some(ref mut next_id) = self.next_id {
+            next_id.reset(Instant::now() + TRY_AGAIN_ON_ERR);
+        }
+    }
+
+    #[inline]
+    fn shutdown(&mut self) {
+        self.next_id = None;
+    }
+
+    fn poll(
+        &mut self,
+    ) -> Poll<
+        Option<
+            ProtocolsHandlerEvent<
+                Self::Protocol,
+                Self::OutboundOpenInfo,
+                PeriodicIdentificationEvent,
+            >,
+        >,
+        io::Error,
+    > {
+        if let Some(pending_result) = self.pending_result.take() {
+            return Ok(Async::Ready(Some(ProtocolsHandlerEvent::Custom(
+                pending_result,
+            ))));
+        }
+
+        let next_id = match self.next_id {
+            Some(ref mut nid) => nid,
+            None => return Ok(Async::Ready(None)),
+        };
+
+        // Poll the future that fires when we need to identify the node again.
+        match next_id.poll() {
+            Ok(Async::NotReady) => Ok(Async::NotReady),
+            Ok(Async::Ready(())) => {
+                next_id.reset(Instant::now() + DELAY_TO_NEXT_ID);
+                let mut upgrade = self.config.clone();
+                upgrade.enable();
+                let ev = ProtocolsHandlerEvent::OutboundSubstreamRequest { upgrade, info: () };
+                Ok(Async::Ready(Some(ev)))
+            }
+            Err(err) => Err(io::Error::new(io::ErrorKind::Other, err)),
+        }
+    }
+}