feat(iroh): introduce endpoint presets (#3523)

## Description

Closes #3470

## Breaking Changes

- removed
  - `iroh::endpoint::Builder::n0_discovery`
  - `iroh::endpoint::Builder::discovery_dht`
  - `iroh::endpoint::Builder::discovery_local_network`
  - `iroh::endpoint::Builder::discovery`
  - `iroh::discovery::DiscoveryContext`
  - `iroh::endpoint::Builder::default`
- added
- `iroh::Endpoint::bind` - this allows to immediately create an
`Endpoint` with the defaults and binds it
  - `iroh::endpoint::Endpoint::empty_builder`
- `iroh::endpoint::presets` - new module, defining a trait on how to
preconfigure and `Endpoint`
- `iroh::endpoint::Builder::new` - creates a new builder with the `N0`
preset
  - `iroh::endpoint::Builder::preset`
- `iroh::endpoint::Builder::empty` - creates a new builder, completely
empty (no discovery, no relay map)
- changed
  - `iroh::'Endpoint::add_discovery` is now called just `discovery`
- `iroh::discovery::IntoDiscovery` now takes an `Endpoint` instead of a
`DiscoveryContext`

---------

Co-authored-by: ramfox <[email protected]>
Co-authored-by: “ramfox” <“[email protected]”>

Author: 3 people

README.md

@@ -60,7 +60,7 @@ Install it using `cargo add iroh`, then on the connecting side:
 ```rs
 const ALPN: &[u8] = b"iroh-example/echo/0";
 
-let endpoint = Endpoint::builder().discovery_n0().bind().await?;
+let endpoint = Endpoint::bind().await?;
 
 // Open a connection to the accepting endpoint
 let conn = endpoint.connect(addr, ALPN).await?;
@@ -85,7 +85,7 @@ endpoint.close().await;
 
 And on the accepting side:
 ```rs
-let endpoint = Endpoint::builder().discovery_n0().bind().await?;
+let endpoint = Endpoint::bind().await?;
 
 let router = Router::builder(endpoint)
     .accept(ALPN.to_vec(), Arc::new(Echo))

iroh/examples/echo-no-router.rs

@@ -33,7 +33,7 @@ async fn main() -> Result<()> {
 }
 
 async fn connect_side(addr: EndpointAddr) -> Result<()> {
-    let endpoint = Endpoint::builder().discovery_n0().bind().await?;
+    let endpoint = Endpoint::bind().await?;
 
     // Open a connection to the accepting endpoint
     let conn = endpoint.connect(addr, ALPN).await?;
@@ -68,7 +68,6 @@ async fn connect_side(addr: EndpointAddr) -> Result<()> {
 
 async fn start_accept_side() -> Result<Endpoint> {
     let endpoint = Endpoint::builder()
-        .discovery_n0()
         // The accept side needs to opt-in to the protocols it accepts,
         // as any connection attempts that can't be found with a matching ALPN
         // will be rejected.

iroh/examples/echo.rs

@@ -35,7 +35,7 @@ async fn main() -> Result<()> {
 }
 
 async fn connect_side(addr: EndpointAddr) -> Result<()> {
-    let endpoint = Endpoint::builder().discovery_n0().bind().await?;
+    let endpoint = Endpoint::bind().await?;
 
     // Open a connection to the accepting endpoint
     let conn = endpoint.connect(addr, ALPN).await?;
@@ -68,7 +68,7 @@ async fn connect_side(addr: EndpointAddr) -> Result<()> {
 }
 
 async fn start_accept_side() -> Result<Router> {
-    let endpoint = Endpoint::builder().discovery_n0().bind().await?;
+    let endpoint = Endpoint::bind().await?;
 
     // Build our protocol handler and add our protocol, identified by its ALPN, and spawn the endpoint.
     let router = Router::builder(endpoint).accept(ALPN, Echo).spawn();

iroh/examples/locally-discovered-nodes.rs

@@ -19,7 +19,7 @@ async fn main() -> Result<()> {
     tracing_subscriber::fmt::init();
     println!("Discovering Local Endpoints Example!");
 
-    let ep = Endpoint::builder().bind().await?;
+    let ep = Endpoint::bind().await?;
     let endpoint_id = ep.id();
 
     let mdns = MdnsDiscovery::builder().build(endpoint_id)?;
@@ -68,7 +68,8 @@ async fn main() -> Result<()> {
     for _ in 0..endpoint_count {
         let ud = user_data.clone();
         set.spawn(async move {
-            let ep = Endpoint::builder().discovery_local_network().bind().await?;
+            let ep = Endpoint::bind().await?;
+            ep.discovery().add(MdnsDiscovery::builder().build(ep.id())?);
             ep.set_user_data_for_discovery(Some(ud));
             tokio::time::sleep(Duration::from_secs(3)).await;
             ep.close().await;

iroh/examples/screening-connection.rs

@@ -46,7 +46,7 @@ async fn main() -> Result<()> {
 }
 
 async fn connect_side(addr: &EndpointAddr) -> Result<()> {
-    let endpoint = Endpoint::builder().discovery_n0().bind().await?;
+    let endpoint = Endpoint::bind().await?;
 
     // Open a connection to the accepting endpoint
     let conn = endpoint.connect(addr.clone(), ALPN).await?;
@@ -79,7 +79,7 @@ async fn connect_side(addr: &EndpointAddr) -> Result<()> {
 }
 
 async fn start_accept_side() -> Result<Router> {
-    let endpoint = Endpoint::builder().discovery_n0().bind().await?;
+    let endpoint = Endpoint::bind().await?;
 
     let echo = ScreenedEcho {
         conn_attempt_count: Arc::new(AtomicU64::new(0)),

iroh/examples/search.rs

@@ -75,7 +75,7 @@ async fn main() -> Result<()> {
     let args = Cli::parse();
 
     // Build an endpoint
-    let endpoint = Endpoint::builder().discovery_n0().bind().await?;
+    let endpoint = Endpoint::bind().await?;
 
     // Build our protocol handler. The `builder` exposes access to various subsystems in the
     // iroh endpoint. In our case, we need a blobs client and the endpoint.

iroh/examples/transfer.rs

@@ -220,27 +220,14 @@ impl EndpointArgs {
             let url = self
                 .pkarr_relay_url
                 .unwrap_or_else(|| self.env.pkarr_relay_url());
-            builder = builder.add_discovery(PkarrPublisher::builder(url));
+            builder = builder.discovery(PkarrPublisher::builder(url));
         }
 
         if !self.no_dns_resolve {
             let domain = self
                 .dns_origin_domain
                 .unwrap_or_else(|| self.env.dns_origin_domain());
-            builder = builder.add_discovery(DnsDiscovery::builder(domain));
-        }
-
-        if self.mdns {
-            #[cfg(feature = "discovery-local-network")]
-            {
-                builder = builder.discovery_local_network();
-            }
-            #[cfg(not(feature = "discovery-local-network"))]
-            {
-                snafu::whatever!(
-                    "Must have the `test-utils` feature enabled when using the `--relay-only` flag"
-                );
-            }
+            builder = builder.discovery(DnsDiscovery::builder(domain));
         }
 
         if self.relay_only {
@@ -270,6 +257,23 @@ impl EndpointArgs {
 
         let endpoint = builder.alpns(vec![TRANSFER_ALPN.to_vec()]).bind().await?;
 
+        if self.mdns {
+            #[cfg(feature = "discovery-local-network")]
+            {
+                use iroh::discovery::mdns::MdnsDiscovery;
+
+                endpoint
+                    .discovery()
+                    .add(MdnsDiscovery::builder().build(endpoint.id())?);
+            }
+            #[cfg(not(feature = "discovery-local-network"))]
+            {
+                snafu::whatever!(
+                    "Must have the `test-utils` feature enabled when using the `--relay-only` flag"
+                );
+            }
+        }
+
         let endpoint_id = endpoint.id();
         println!("Our endpoint id:\n\t{endpoint_id}");