Add a IdentifyTransport (#569)

* Add a IdentifyTransport

* Retreiver -> Retriever

* Move the muxer in the IdRetrieverState

protocols/identify/src/id_transport.rs

@@ -0,0 +1,229 @@
+// 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.
+
+//! Contains the `IdentifyTransport` type.
+
+use futures::prelude::*;
+use libp2p_core::{Endpoint, Multiaddr, PeerId, PublicKey, Transport, muxing, upgrade::apply};
+use protocol::{IdentifyOutput, IdentifyProtocolConfig};
+use std::io::{Error as IoError, ErrorKind as IoErrorKind};
+use std::mem;
+use std::sync::Arc;
+
+/// Wraps around an implementation of `Transport` that yields a muxer. Will use the muxer to
+/// open a substream with the remote and retreive its peer id. Then yields a
+/// `(PeerId, impl StreamMuxer)`.
+///
+/// This transport can be used if you don't use any encryption layer, or if you want to make
+/// encryption optional, in which case you have no other way to know the `PeerId` of the remote
+/// than to ask for it.
+///
+/// > **Note**: If you use this transport, keep in mind that the `PeerId` returned by the remote
+/// >           can be anything and shouldn't necessarily be trusted.
+#[derive(Debug, Clone)]
+pub struct IdentifyTransport<TTrans> {
+    /// The underlying transport we wrap around.
+    transport: TTrans,
+}
+
+impl<TTrans> IdentifyTransport<TTrans> {
+    /// Creates an `IdentifyTransport` that wraps around the given transport.
+    #[inline]
+    pub fn new(transport: TTrans) -> Self {
+        IdentifyTransport {
+            transport,
+        }
+    }
+}
+
+// TODO: don't use boxes
+impl<TTrans, TMuxer> Transport for IdentifyTransport<TTrans>
+where
+    TTrans: Transport<Output = TMuxer>,
+    TMuxer: muxing::StreamMuxer + Send + Sync + 'static,      // TODO: remove unnecessary bounds
+    TMuxer::Substream: Send + Sync + 'static,      // TODO: remove unnecessary bounds
+    TMuxer::OutboundSubstream: Send + 'static,      // TODO: remove unnecessary bounds
+    TTrans::Dial: Send + Sync + 'static,
+    TTrans::Listener: Send + 'static,
+    TTrans::ListenerUpgrade: Send + 'static,
+{
+    type Output = (PeerId, TMuxer);
+    type Listener = Box<Stream<Item = (Self::ListenerUpgrade, Multiaddr), Error = IoError> + Send>;
+    type ListenerUpgrade = Box<Future<Item = Self::Output, Error = IoError> + Send>;
+    type Dial = Box<Future<Item = Self::Output, Error = IoError> + Send>;
+
+    #[inline]
+    fn listen_on(self, addr: Multiaddr) -> Result<(Self::Listener, Multiaddr), (Self, Multiaddr)> {
+        let (listener, new_addr) = match self.transport.listen_on(addr) {
+            Ok((l, a)) => (l, a),
+            Err((inner, addr)) => {
+                let id = IdentifyTransport {
+                    transport: inner,
+                };
+                return Err((id, addr));
+            }
+        };
+
+        let listener = listener
+            .map(move |(upgrade, remote_addr)| {
+                let upgr = upgrade
+                    .and_then(move |muxer| {
+                        IdRetriever::new(muxer, IdentifyProtocolConfig, Endpoint::Listener)
+                    });
+                (Box::new(upgr) as Box<Future<Item = _, Error = _> + Send>, remote_addr)
+            });
+
+        Ok((Box::new(listener) as Box<_>, new_addr))
+    }
+
+    #[inline]
+    fn dial(self, addr: Multiaddr) -> Result<Self::Dial, (Self, Multiaddr)> {
+        // We dial a first time the node.
+        let dial = match self.transport.dial(addr.clone()) {
+            Ok(d) => d,
+            Err((transport, addr)) => {
+                let id = IdentifyTransport {
+                    transport,
+                };
+                return Err((id, addr));
+            }
+        };
+
+        let dial = dial.and_then(move |muxer| {
+            IdRetriever::new(muxer, IdentifyProtocolConfig, Endpoint::Dialer)
+        });
+
+        Ok(Box::new(dial) as Box<_>)
+    }
+
+    #[inline]
+    fn nat_traversal(&self, a: &Multiaddr, b: &Multiaddr) -> Option<Multiaddr> {
+        self.transport.nat_traversal(a, b)
+    }
+}
+
+/// Implementation of `Future` that asks the remote of its `PeerId`.
+// TODO: remove unneeded bounds
+struct IdRetriever<TMuxer>
+where TMuxer: muxing::StreamMuxer + Send + Sync + 'static,
+      TMuxer::Substream: Send,
+{
+    /// Internal state.
+    state: IdRetrieverState<TMuxer>,
+    /// Whether we're dialing or listening.
+    endpoint: Endpoint,
+}
+
+enum IdRetrieverState<TMuxer>
+where TMuxer: muxing::StreamMuxer + Send + Sync + 'static,
+      TMuxer::Substream: Send,
+{
+    /// We are in the process of opening a substream with the remote.
+    OpeningSubstream(Arc<TMuxer>, muxing::OutboundSubstreamRefWrapFuture<Arc<TMuxer>>, IdentifyProtocolConfig),
+    /// We opened the substream and are currently negotiating the identify protocol.
+    NegotiatingIdentify(Arc<TMuxer>, apply::UpgradeApplyFuture<muxing::SubstreamRef<Arc<TMuxer>>, IdentifyProtocolConfig>),
+    /// We retreived the remote's public key and are ready to yield it when polled again.
+    Finishing(Arc<TMuxer>, PublicKey),
+    /// Something bad happend, or the `Future` is finished, and shouldn't be polled again.
+    Poisoned,
+}
+
+impl<TMuxer> IdRetriever<TMuxer>
+where TMuxer: muxing::StreamMuxer + Send + Sync + 'static,
+      TMuxer::Substream: Send,
+{
+    /// Creates a new `IdRetriever` ready to be polled.
+    fn new(muxer: TMuxer, config: IdentifyProtocolConfig, endpoint: Endpoint) -> Self {
+        let muxer = Arc::new(muxer);
+        let opening = muxing::outbound_from_ref_and_wrap(muxer.clone());
+
+        IdRetriever {
+            state: IdRetrieverState::OpeningSubstream(muxer, opening, config),
+            endpoint,
+        }
+    }
+}
+
+impl<TMuxer> Future for IdRetriever<TMuxer>
+where TMuxer: muxing::StreamMuxer + Send + Sync + 'static,
+      TMuxer::Substream: Send,
+{
+    type Item = (PeerId, TMuxer);
+    type Error = IoError;
+
+    fn poll(&mut self) -> Poll<Self::Item, Self::Error> {
+        // This loop is here so that we can continue polling until we're ready.
+        loop {
+            // In order to satisfy the borrow checker, we extract the state and temporarily put
+            // `Poisoned` instead.
+            match mem::replace(&mut self.state, IdRetrieverState::Poisoned) {
+                IdRetrieverState::OpeningSubstream(muxer, mut opening, config) => {
+                    match opening.poll() {
+                        Ok(Async::Ready(Some(substream))) => {
+                            let upgrade = apply::apply(substream, config, self.endpoint);
+                            self.state = IdRetrieverState::NegotiatingIdentify(muxer, upgrade);
+                        },
+                        Ok(Async::Ready(None)) => {
+                            return Err(IoError::new(IoErrorKind::Other, "remote refused our identify attempt"));
+                        },
+                        Ok(Async::NotReady) => {
+                            self.state = IdRetrieverState::OpeningSubstream(muxer, opening, config);
+                            return Ok(Async::NotReady);
+                        },
+                        Err(err) => return Err(err),
+                    }
+                },
+                IdRetrieverState::NegotiatingIdentify(muxer, mut nego) => {
+                    match nego.poll() {
+                        Ok(Async::Ready(IdentifyOutput::RemoteInfo { info, .. })) => {
+                            self.state = IdRetrieverState::Finishing(muxer, info.public_key);
+                        },
+                        Ok(Async::Ready(IdentifyOutput::Sender { .. })) => {
+                            unreachable!("IdentifyOutput::Sender can never be the output from \
+                                          the dialing side");
+                        },
+                        Ok(Async::NotReady) => {
+                            self.state = IdRetrieverState::NegotiatingIdentify(muxer, nego);
+                            return Ok(Async::NotReady);
+                        },
+                        Err(err) => return Err(err),
+                    }
+                },
+                IdRetrieverState::Finishing(muxer, public_key) => {
+                    // Here is a tricky part: we need to get back the muxer in order to return
+                    // it, but it is in an `Arc`.
+                    let unwrapped = Arc::try_unwrap(muxer).unwrap_or_else(|_| {
+                        panic!("we clone the Arc only to put it into substreams ; once in the \
+                                Finishing state, no substream or upgrade exists anymore ; \
+                                therefore there exists only one instance of the Arc ; qed")
+                    });
+
+                    // We leave `Poisoned` as the state when returning.
+                    return Ok(Async::Ready((public_key.into(), unwrapped)));
+                },
+                IdRetrieverState::Poisoned => {
+                    panic!("Future state panicked inside poll() or is finished")
+                },
+            }
+        }
+    }
+}
+
+// TODO: write basic working test

protocols/identify/src/lib.rs

@@ -81,10 +81,12 @@ extern crate tokio_timer;
 extern crate unsigned_varint;
 extern crate void;
 
+pub use self::id_transport::IdentifyTransport;
 pub use self::periodic_id_handler::{PeriodicIdentification, PeriodicIdentificationEvent};
 pub use self::protocol::{IdentifyInfo, IdentifyOutput};
 pub use self::protocol::{IdentifyProtocolConfig, IdentifySender};
 
+mod id_transport;
 mod periodic_id_handler;
 mod protocol;
 mod structs_proto;