protocols/relay: Implement circuit relay v2 protocol (#2059)

This commit adds an implementation for the circuit relay v2 protocol to be used
as a relay server, i.e. it supports incoming HOP requests and outgoing STOP
requests and used as a relay clients, i.e. outgoing HOP requests and incoming
STOP requests.

The existing circuit relay v1 protocol implementation is moved to
protocols/relay/src/v1.

Co-authored-by: ronzigelman <ronzigelman@gmail.com>
Co-authored-by: Marco Munizaga <git@marcopolo.io>
Co-authored-by: Thomas Eizinger <thomas@eizinger.io>
Co-authored-by: Elena Frank <57632201+elenaf9@users.noreply.github.com>

misc/metrics/src/relay.rs

@@ -0,0 +1,114 @@
+// Copyright 2021 Protocol Labs.
+//
+// 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 open_metrics_client::encoding::text::Encode;
+use open_metrics_client::metrics::counter::Counter;
+use open_metrics_client::metrics::family::Family;
+use open_metrics_client::registry::Registry;
+
+pub struct Metrics {
+    events: Family<EventLabels, Counter>,
+}
+
+impl Metrics {
+    pub fn new(registry: &mut Registry) -> Self {
+        let sub_registry = registry.sub_registry_with_prefix("relay");
+
+        let events = Family::default();
+        sub_registry.register(
+            "events",
+            "Events emitted by the relay NetworkBehaviour",
+            Box::new(events.clone()),
+        );
+
+        Self { events }
+    }
+}
+
+#[derive(Debug, Clone, Hash, PartialEq, Eq, Encode)]
+struct EventLabels {
+    event: EventType,
+}
+
+#[derive(Debug, Clone, Hash, PartialEq, Eq, Encode)]
+enum EventType {
+    ReservationReqAccepted,
+    ReservationReqAcceptFailed,
+    ReservationReqDenied,
+    ReservationReqDenyFailed,
+    ReservationTimedOut,
+    CircuitReqReceiveFailed,
+    CircuitReqDenied,
+    CircuitReqDenyFailed,
+    CircuitReqOutboundConnectFailed,
+    CircuitReqAccepted,
+    CircuitReqAcceptFailed,
+    CircuitClosed,
+}
+
+impl From<&libp2p_relay::v2::relay::Event> for EventType {
+    fn from(event: &libp2p_relay::v2::relay::Event) -> Self {
+        match event {
+            libp2p_relay::v2::relay::Event::ReservationReqAccepted { .. } => {
+                EventType::ReservationReqAccepted
+            }
+            libp2p_relay::v2::relay::Event::ReservationReqAcceptFailed { .. } => {
+                EventType::ReservationReqAcceptFailed
+            }
+            libp2p_relay::v2::relay::Event::ReservationReqDenied { .. } => {
+                EventType::ReservationReqDenied
+            }
+            libp2p_relay::v2::relay::Event::ReservationReqDenyFailed { .. } => {
+                EventType::ReservationReqDenyFailed
+            }
+            libp2p_relay::v2::relay::Event::ReservationTimedOut { .. } => {
+                EventType::ReservationTimedOut
+            }
+            libp2p_relay::v2::relay::Event::CircuitReqReceiveFailed { .. } => {
+                EventType::CircuitReqReceiveFailed
+            }
+            libp2p_relay::v2::relay::Event::CircuitReqDenied { .. } => EventType::CircuitReqDenied,
+            libp2p_relay::v2::relay::Event::CircuitReqOutboundConnectFailed { .. } => {
+                EventType::CircuitReqOutboundConnectFailed
+            }
+            libp2p_relay::v2::relay::Event::CircuitReqDenyFailed { .. } => {
+                EventType::CircuitReqDenyFailed
+            }
+            libp2p_relay::v2::relay::Event::CircuitReqAccepted { .. } => {
+                EventType::CircuitReqAccepted
+            }
+            libp2p_relay::v2::relay::Event::CircuitReqAcceptFailed { .. } => {
+                EventType::CircuitReqAcceptFailed
+            }
+            libp2p_relay::v2::relay::Event::CircuitClosed { .. } => EventType::CircuitClosed,
+        }
+    }
+}
+
+impl super::Recorder<libp2p_relay::v2::relay::Event> for super::Metrics {
+    fn record(&self, event: &libp2p_relay::v2::relay::Event) {
+        self.relay
+            .events
+            .get_or_create(&EventLabels {
+                event: event.into(),
+            })
+            .inc();
+    }
+}