ref(iroh-net)!: Make Endpoint::close not consume self (#2882)

## Description

The endpoint can be freely cloned, so consuming `self` on shutdown is
somewhat fruitless. This changes it to take `&self` like a normal
method.

## Breaking Changes

- `Endpoint::close` now takes `&self` rather than `self`. This can in
some situations mean an existing (clone of an) endpoint might be dropped
too early as a temporary variable.

## Notes & open questions

## Change checklist

- [x] Self-review.
- [x] Documentation updates following the [style
guide](https://rust-lang.github.io/rfcs/1574-more-api-documentation-conventions.html#appendix-a-full-conventions-text),
if relevant.
- [x] Tests if relevant.
- [x] All breaking changes documented.

---------

Co-authored-by: iacore <noreply+gpg-stub@1a-insec.net>
Co-authored-by: Floris Bruynooghe <flub@devork.be>
Co-authored-by: Floris Bruynooghe <flub@n0.computer>

iroh-net/src/endpoint.rs

@@ -964,7 +964,7 @@ impl Endpoint {
     ///
     /// Returns an error if closing the magic socket failed.
     /// TODO: Document error cases.
-    pub async fn close(self, error_code: VarInt, reason: &[u8]) -> Result<()> {
+    pub async fn close(&self, error_code: VarInt, reason: &[u8]) -> Result<()> {
         let Endpoint {
             msock,
             endpoint,
@@ -975,9 +975,7 @@ impl Endpoint {
         tracing::debug!("Closing connections");
         endpoint.close(error_code, reason);
         endpoint.wait_idle().await;
-        // In case this is the last clone of `Endpoint`, dropping the `quinn::Endpoint` will
-        // make it more likely that the underlying socket is not polled by quinn anymore after this
-        drop(endpoint);
+
         tracing::debug!("Connections closed");
 
         msock.close().await?;

iroh-router/src/router.rs

@@ -181,9 +181,7 @@ async fn shutdown(endpoint: &Endpoint, protocols: Arc<ProtocolMap>) {
         // Closing the Endpoint is the equivalent of calling Connection::close on all
         // connections: Operations will immediately fail with ConnectionError::LocallyClosed.
         // All streams are interrupted, this is not graceful.
-        endpoint
-            .clone()
-            .close(error_code.into(), b"provider terminating"),
+        endpoint.close(error_code.into(), b"provider terminating"),
         // Shutdown protocol handlers.
         protocols.shutdown(),
     );