refactor(iroh)!: Use FourTuple for selected path (#4273)

## Description

Track the selected path in the RemoteStateActor by FourTuple.

Handling and exposing the local address is .. weird:

 * For IP transports, it is the address of the local socket, if known
* For relay transports, we never set the local_ip in the recv meta.
* For custom transports, the custom transport implementation can set a
`CustomAddr` in `RecvMeta`, which we convert to a mapped addr with port
0 internally in the recv path

The address we get back from noq for a path is this address. We don't
want to ever expose mapped addresses, so we need to convert this address
into something else. We have a precedent: We recently introduced a
`IncomingLocalAddr` which is basically this.

So I decided to reuse this type and renam eit to `LocalTransportAddr`,
which mirrors `TransportAddr` nicely.
The conversions are nothing to be happy about, but I don't see a solid
alternative right now without larger refactors.


## Breaking Changes

* changed: The variants of `iroh::endpoint::PathEvent` are now marked
`#[non_exhaustive]`
* renamed: `iroh::endpoint::IncomingLocalAddr` ->
`iroh::endpoint::LocalTransportAddr`, and the `Relay` variant is now a
tuple variant

## Notes & open questions

Instead of reusing and renaming the exisitng `IncomingLocalAddr`, we
could also expose local_addr as `Option<LocalTransportAddr>`, with `enum
LocalTransportAddr { Ip(IpAddr), Custom(CustomAddr) }`, i.e. remove the
`Relay` case. I had this in an earlier version but then found yet
another public address type a bit too much so instead went for the
existing `IncomingLocalAddr`.

## Change checklist
<!-- Remove any that are not relevant. -->
- [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.

Author: Frando

iroh/examples/transfer.rs

@@ -961,6 +961,7 @@ fn spawn_path_watcher(
                     id,
                     remote_addr,
                     last_stats,
+                    ..
                 } => {
                     paths.push(PathData {
                         id,

iroh/src/endpoint.rs

@@ -42,6 +42,7 @@ pub use super::socket::{
         Path, PathEvent, PathEventStream, PathList, PathListIter, PathListStream, RemoteInfo,
         TransportAddrInfo, TransportAddrUsage,
     },
+    transports::LocalTransportAddr,
 };
 #[cfg(wasm_browser)]
 use crate::address_lookup::PkarrResolver;
@@ -81,8 +82,8 @@ pub use self::quic::{QlogConfig, QlogFactory, QlogFileFactory};
 pub use self::{
     connection::{
         Accept, Accepting, AlpnError, AuthenticationError, Connecting, ConnectingError, Connection,
-        ConnectionState, HandshakeCompleted, Incoming, IncomingAddr, IncomingLocalAddr,
-        IncomingZeroRtt, IncomingZeroRttConnection, OutgoingZeroRtt, OutgoingZeroRttConnection,
+        ConnectionState, HandshakeCompleted, Incoming, IncomingAddr, IncomingZeroRtt,
+        IncomingZeroRttConnection, OutgoingZeroRtt, OutgoingZeroRttConnection,
         RemoteEndpointIdError, RetryError, WeakConnectionHandle, ZeroRttStatus,
     },
     quic::{
@@ -1682,11 +1683,6 @@ impl Endpoint {
         self.inner.to_transport_addr(addr)
     }
 
-    /// Reverse-resolves a custom mapped address back to its [`iroh_base::CustomAddr`].
-    pub(crate) fn lookup_custom_addr(&self, addr: SocketAddr) -> Option<iroh_base::CustomAddr> {
-        self.inner.lookup_custom_addr(addr)
-    }
-
     #[cfg(all(test, with_crypto_provider))]
     pub(crate) fn inner(&self) -> Result<Arc<EndpointInner>, EndpointError> {
         if self.is_closed() {
@@ -3491,7 +3487,7 @@ mod tests {
                 if let PathEvent::Closed {
                     remote_addr,
                     last_stats,
-                    id: _,
+                    ..
                 } = event
                 {
                     stats.insert(remote_addr, *last_stats);

iroh/src/endpoint/connection.rs

@@ -19,7 +19,7 @@
 use std::{
     any::Any,
     future::{Future, IntoFuture},
-    net::{IpAddr, SocketAddr},
+    net::SocketAddr,
     pin::Pin,
     sync::Arc,
     task::Poll,
@@ -48,7 +48,7 @@ use crate::{
     socket::{
         RemoteStateActorStoppedError,
         remote_map::{PathEventStream, PathList, PathListStream, PathStateReceiver},
-        transports,
+        transports::{self, LocalTransportAddr},
     },
 };
 
@@ -92,21 +92,6 @@ impl From<transports::Addr> for IncomingAddr {
     }
 }
 
-/// The local address that received an incoming connection.
-#[derive(Debug, Clone, PartialEq, Eq)]
-#[non_exhaustive]
-pub enum IncomingLocalAddr {
-    /// The local IP, if the OS surfaced it.
-    Ip(Option<IpAddr>),
-    /// The relay this connection arrived through.
-    Relay {
-        /// The URL of the relay.
-        url: RelayUrl,
-    },
-    /// The local custom address, if the transport reports one.
-    Custom(Option<iroh_base::CustomAddr>),
-}
-
 /// Future produced by [`Endpoint::accept`].
 #[derive(derive_more::Debug)]
 #[pin_project]
@@ -208,18 +193,10 @@ impl Incoming {
     }
 
     /// Returns the local address that received this incoming connection.
-    pub fn local_addr(&self) -> IncomingLocalAddr {
-        match self.ep.to_transport_addr(self.inner.remote_address()) {
-            transports::Addr::Ip(_) => IncomingLocalAddr::Ip(self.inner.local_ip()),
-            transports::Addr::Relay(url, _) => IncomingLocalAddr::Relay { url },
-            transports::Addr::Custom(_) => {
-                let local = self
-                    .inner
-                    .local_ip()
-                    .and_then(|ip| self.ep.lookup_custom_addr(SocketAddr::new(ip, 0)));
-                IncomingLocalAddr::Custom(local)
-            }
-        }
+    pub fn local_addr(&self) -> LocalTransportAddr {
+        let remote_addr = self.inner.remote_address();
+        let local_ip = self.inner.local_ip();
+        self.ep.inner.to_local_transport_addr(local_ip, remote_addr)
     }
 
     /// Returns the remote address of this incoming connection.

iroh/src/socket.rs

@@ -68,7 +68,9 @@ use crate::net_report::QuicConfig;
 use crate::{
     address_lookup::{self, AddressLookupFailed, EndpointData, UserData},
     defaults::timeouts::NET_REPORT_TIMEOUT,
-    endpoint::{RelayStatus, hooks::EndpointHooksList, quic::QuicTransportConfig},
+    endpoint::{
+        LocalTransportAddr, RelayStatus, hooks::EndpointHooksList, quic::QuicTransportConfig,
+    },
     metrics::EndpointMetrics,
     net_report::{self, IfStateDetails, Report},
     portmapper,
@@ -533,14 +535,17 @@ impl Socket {
         .unwrap_or(transports::Addr::Ip(addr))
     }
 
-    /// Reverse-resolves a custom mapped address back to its [`iroh_base::CustomAddr`].
-    pub(crate) fn lookup_custom_addr(&self, addr: SocketAddr) -> Option<iroh_base::CustomAddr> {
-        match MultipathMappedAddr::from(addr) {
-            MultipathMappedAddr::Custom(custom_mapped) => {
-                self.mapped_addrs.custom_addrs.lookup(&custom_mapped)
-            }
-            _ => None,
-        }
+    pub(crate) fn to_local_transport_addr(
+        &self,
+        local_ip: Option<IpAddr>,
+        remote_addr: SocketAddr,
+    ) -> LocalTransportAddr {
+        let remote_addr = self.to_transport_addr(remote_addr);
+        LocalTransportAddr::from_noq_local_ip(
+            local_ip,
+            &remote_addr,
+            &self.mapped_addrs.custom_addrs,
+        )
     }
 
     /// Reference to the internal Address Lookup

iroh/src/socket/mapped_addrs.rs

@@ -287,6 +287,17 @@ impl MappedAddr for CustomMappedAddr {
     }
 }
 
+impl TryFrom<IpAddr> for CustomMappedAddr {
+    type Error = CustomMappedAddrError;
+
+    fn try_from(value: IpAddr) -> std::result::Result<Self, Self::Error> {
+        match value {
+            IpAddr::V4(_) => Err(e!(CustomMappedAddrError)),
+            IpAddr::V6(addr) => addr.try_into(),
+        }
+    }
+}
+
 impl TryFrom<Ipv6Addr> for CustomMappedAddr {
     type Error = CustomMappedAddrError;