chore(relay): move server example to examples/

Related: #3111.

Pull-Request: #3663.

examples/relay-server/src/main.rs

@@ -0,0 +1,123 @@
+// Copyright 2020 Parity Technologies (UK) Ltd.
+// 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 clap::Parser;
+use futures::executor::block_on;
+use futures::stream::StreamExt;
+use libp2p::{
+    core::multiaddr::Protocol,
+    core::upgrade,
+    core::{Multiaddr, Transport},
+    identify, identity,
+    identity::PeerId,
+    noise, ping, relay,
+    swarm::{NetworkBehaviour, SwarmBuilder, SwarmEvent},
+    tcp,
+};
+use std::error::Error;
+use std::net::{Ipv4Addr, Ipv6Addr};
+
+fn main() -> Result<(), Box<dyn Error>> {
+    env_logger::init();
+
+    let opt = Opt::parse();
+    println!("opt: {opt:?}");
+
+    // Create a static known PeerId based on given secret
+    let local_key: identity::Keypair = generate_ed25519(opt.secret_key_seed);
+    let local_peer_id = PeerId::from(local_key.public());
+    println!("Local peer id: {local_peer_id:?}");
+
+    let tcp_transport = tcp::async_io::Transport::default();
+
+    let transport = tcp_transport
+        .upgrade(upgrade::Version::V1)
+        .authenticate(
+            noise::NoiseAuthenticated::xx(&local_key)
+                .expect("Signing libp2p-noise static DH keypair failed."),
+        )
+        .multiplex(libp2p::yamux::YamuxConfig::default())
+        .boxed();
+
+    let behaviour = Behaviour {
+        relay: relay::Behaviour::new(local_peer_id, Default::default()),
+        ping: ping::Behaviour::new(ping::Config::new()),
+        identify: identify::Behaviour::new(identify::Config::new(
+            "/TODO/0.0.1".to_string(),
+            local_key.public(),
+        )),
+    };
+
+    let mut swarm = SwarmBuilder::without_executor(transport, behaviour, local_peer_id).build();
+
+    // Listen on all interfaces
+    let listen_addr = Multiaddr::empty()
+        .with(match opt.use_ipv6 {
+            Some(true) => Protocol::from(Ipv6Addr::UNSPECIFIED),
+            _ => Protocol::from(Ipv4Addr::UNSPECIFIED),
+        })
+        .with(Protocol::Tcp(opt.port));
+    swarm.listen_on(listen_addr)?;
+
+    block_on(async {
+        loop {
+            match swarm.next().await.expect("Infinite Stream.") {
+                SwarmEvent::Behaviour(event) => {
+                    println!("{event:?}")
+                }
+                SwarmEvent::NewListenAddr { address, .. } => {
+                    println!("Listening on {address:?}");
+                }
+                _ => {}
+            }
+        }
+    })
+}
+
+#[derive(NetworkBehaviour)]
+struct Behaviour {
+    relay: relay::Behaviour,
+    ping: ping::Behaviour,
+    identify: identify::Behaviour,
+}
+
+fn generate_ed25519(secret_key_seed: u8) -> identity::Keypair {
+    let mut bytes = [0u8; 32];
+    bytes[0] = secret_key_seed;
+
+    identity::Keypair::ed25519_from_bytes(bytes).expect("only errors on wrong length")
+}
+
+#[derive(Debug, Parser)]
+#[clap(name = "libp2p relay")]
+struct Opt {
+    /// Determine if the relay listen on ipv6 or ipv4 loopback address. the default is ipv4
+    #[clap(long)]
+    use_ipv6: Option<bool>,
+
+    /// Fixed value to generate deterministic peer id
+    #[clap(long)]
+    secret_key_seed: u8,
+
+    /// The port used to listen on all interfaces
+    #[clap(long)]
+    port: u16,
+}