Split ConnectionUpgrade. (#642)

Introduce `InboundUpgrade` and `OutboundUpgrade`.

protocols/plaintext/src/lib.rs

@@ -0,0 +1,63 @@
+// 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.
+
+extern crate bytes;
+extern crate futures;
+extern crate libp2p_core;
+extern crate void;
+
+use bytes::Bytes;
+use futures::future::{self, FutureResult};
+use libp2p_core::{InboundUpgrade, OutboundUpgrade, UpgradeInfo};
+use std::iter;
+use void::Void;
+
+#[derive(Debug, Copy, Clone)]
+pub struct PlainTextConfig;
+
+impl UpgradeInfo for PlainTextConfig {
+    type UpgradeId = ();
+    type NamesIter = iter::Once<(Bytes, Self::UpgradeId)>;
+
+    fn protocol_names(&self) -> Self::NamesIter {
+        iter::once((Bytes::from("/plaintext/1.0.0"), ()))
+    }
+}
+
+impl<C> InboundUpgrade<C> for PlainTextConfig {
+    type Output = C;
+    type Error = Void;
+    type Future = FutureResult<C, Self::Error>;
+
+    fn upgrade_inbound(self, i: C, _: Self::UpgradeId) -> Self::Future {
+        future::ok(i)
+    }
+}
+
+impl<C> OutboundUpgrade<C> for PlainTextConfig {
+    type Output = C;
+    type Error = Void;
+    type Future = FutureResult<C, Self::Error>;
+
+    fn upgrade_outbound(self, i: C, _: Self::UpgradeId) -> Self::Future {
+        future::ok(i)
+    }
+}
+