Make some things infallible

iroh-relay/src/server/clients.rs

@@ -71,7 +71,7 @@ impl Clients {
     /// peer is gone from the network.
     ///
     /// Must be passed a matching connection_id.
-    pub(super) async fn unregister<'a>(&self, connection_id: u64, node_id: NodeId) {
+    pub(super) async fn unregister(&self, connection_id: u64, node_id: NodeId) {
         trace!(
             node_id = node_id.fmt_short(),
             connection_id,

iroh/examples/dht_discovery.rs

@@ -88,7 +88,7 @@ async fn chat_server(args: Args) -> anyhow::Result<()> {
         };
         tokio::spawn(async move {
             let connection = connecting.await?;
-            let remote_node_id = connection.remote_node_id()?;
+            let remote_node_id = connection.remote_node_id();
             println!("got connection from {}", remote_node_id);
             // just leave the tasks hanging. this is just an example.
             let (mut writer, mut reader) = connection.accept_bi().await?;

iroh/examples/echo.rs

@@ -77,7 +77,7 @@ impl ProtocolHandler for Echo {
             // Wait for the connection to be fully established.
             let connection = connecting.await?;
             // We can get the remote's node id from the connection.
-            let node_id = connection.remote_node_id()?;
+            let node_id = connection.remote_node_id();
             println!("accepted connection from {node_id}");
 
             // Our protocol is a simple request-response protocol, so we expect the

iroh/examples/listen-unreliable.rs

@@ -58,7 +58,7 @@ async fn main() -> anyhow::Result<()> {
     // accept incoming connections, returns a normal QUIC connection
 
     while let Some(incoming) = endpoint.accept().await {
-        let mut connecting = match incoming.accept() {
+        let connecting = match incoming.accept() {
             Ok(connecting) => connecting,
             Err(err) => {
                 warn!("incoming connection failed: {err:#}");
@@ -67,9 +67,9 @@ async fn main() -> anyhow::Result<()> {
                 continue;
             }
         };
-        let alpn = connecting.alpn().await?;
         let conn = connecting.await?;
-        let node_id = conn.remote_node_id()?;
+        let alpn = conn.alpn();
+        let node_id = conn.remote_node_id();
         info!(
             "new (unreliable) connection from {node_id} with ALPN {} (coming from {})",
             String::from_utf8_lossy(&alpn),

iroh/examples/listen.rs

@@ -59,7 +59,7 @@ async fn main() -> anyhow::Result<()> {
     );
     // accept incoming connections, returns a normal QUIC connection
     while let Some(incoming) = endpoint.accept().await {
-        let mut connecting = match incoming.accept() {
+        let connecting = match incoming.accept() {
             Ok(connecting) => connecting,
             Err(err) => {
                 warn!("incoming connection failed: {err:#}");
@@ -68,9 +68,9 @@ async fn main() -> anyhow::Result<()> {
                 continue;
             }
         };
-        let alpn = connecting.alpn().await?;
         let conn = connecting.await?;
-        let node_id = conn.remote_node_id()?;
+        let alpn = conn.alpn();
+        let node_id = conn.remote_node_id();
         info!(
             "new connection from {node_id} with ALPN {} (coming from {})",
             String::from_utf8_lossy(&alpn),

iroh/examples/search.rs

@@ -134,7 +134,7 @@ impl ProtocolHandler for BlobSearch {
             // Wait for the connection to be fully established.
             let connection = connecting.await?;
             // We can get the remote's node id from the connection.
-            let node_id = connection.remote_node_id()?;
+            let node_id = connection.remote_node_id();
             println!("accepted connection from {node_id}");
 
             // Our protocol is a simple request-response protocol, so we expect the

iroh/examples/transfer.rs

@@ -121,7 +121,7 @@ async fn provide(size: u64, relay_url: Option<String>, relay_only: bool) -> anyh
             }
         };
         let conn = connecting.await?;
-        let node_id = conn.remote_node_id()?;
+        let node_id = conn.remote_node_id();
         info!(
             "new connection from {node_id} with ALPN {} (coming from {})",
             String::from_utf8_lossy(TRANSFER_ALPN),

iroh/src/endpoint.rs

@@ -1257,16 +1257,24 @@ impl Connecting {
     }
 
     /// Extracts the ALPN protocol from the peer's handshake data.
-    // Note, we could totally provide this method to be on a Connection as well.  But we'd
-    // need to wrap Connection too.
-    pub async fn alpn(&mut self) -> Result<Vec<u8>> {
+    pub async fn alpn(&mut self) -> Result<Vec<u8>, ConnectionError> {
         let data = self.handshake_data().await?;
-        match data.downcast::<quinn::crypto::rustls::HandshakeData>() {
-            Ok(data) => match data.protocol {
-                Some(protocol) => Ok(protocol),
-                None => bail!("no ALPN protocol available"),
-            },
-            Err(_) => bail!("unknown handshake type"),
+        let data = data
+            .downcast::<quinn::crypto::rustls::HandshakeData>()
+            .expect("fixed crypto setup for iroh");
+        match data.protocol {
+            Some(proto) => Ok(proto),
+            None => {
+                // Using QUIC's CONNECTION_REFUSED error on the server-side is a bit odd,
+                // but perhaps not a total crime.  Strictly speaking for QUIC this is an
+                // application error, but if we surfaced this as an application error it
+                // would be even more confusing for the user.
+                Err(ConnectionError::TransportError(TransportError {
+                    code: TransportErrorCode::CONNECTION_REFUSED,
+                    frame: None,
+                    reason: String::from("iroh connections must use an ALPN"),
+                }))
+            }
         }
     }
 }
@@ -1281,6 +1289,27 @@ impl Future for Connecting {
             Poll::Ready(Err(err)) => Poll::Ready(Err(err)),
             Poll::Ready(Ok(inner)) => {
                 let conn = Connection { inner };
+
+                // An iroh connection MUST always have an ALPN.  Note that this check is
+                // only valid for accepting connections, but we **currently** do not use
+                // this `Connecting` struct when establishing connections.  Once we do we'll
+                // have to make this check conditional.
+                let handshake_data = conn.handshake_data();
+                let handshake_data = handshake_data
+                    .downcast::<quinn::crypto::rustls::HandshakeData>()
+                    .expect("fixed crypto setup for iroh");
+                if handshake_data.protocol.is_none() {
+                    // Using QUIC's CONNECTION_REFUSED error on the server-side is a bit odd,
+                    // but perhaps not a total crime.  Strictly speaking for QUIC this is an
+                    // application error, but if we surfaced this as an application error it
+                    // would be even more confusing for the user.
+                    return Poll::Ready(Err(ConnectionError::TransportError(TransportError {
+                        code: TransportErrorCode::CONNECTION_REFUSED,
+                        frame: None,
+                        reason: String::from("iroh connections must use an ALPN"),
+                    })));
+                }
+
                 try_send_rtt_msg(&conn, this.ep);
                 Poll::Ready(Ok(conn))
             }
@@ -1511,17 +1540,20 @@ impl Connection {
     ///
     /// [`Connection::handshake_data()`]: crate::Connecting::handshake_data
     #[inline]
-    pub fn handshake_data(&self) -> Option<Box<dyn Any>> {
-        self.inner.handshake_data()
+    pub fn handshake_data(&self) -> Box<dyn Any> {
+        self.inner
+            .handshake_data()
+            .expect("we always have handshake data")
     }
 
     /// Extracts the ALPN protocol from the peer's handshake data.
-    pub fn alpn(&self) -> Option<Vec<u8>> {
-        let data = self.handshake_data()?;
-        match data.downcast::<quinn::crypto::rustls::HandshakeData>() {
-            Ok(data) => data.protocol,
-            Err(_) => None,
-        }
+    pub fn alpn(&self) -> Vec<u8> {
+        let data = self.handshake_data();
+        let data = data
+            .downcast::<quinn::crypto::rustls::HandshakeData>()
+            .expect("fixed crypto setup for iroh");
+        data.protocol
+            .expect("checked in <Connecting as Future>::poll")
     }
 
     /// Cryptographic identity of the peer.
@@ -1533,8 +1565,10 @@ impl Connection {
     /// [`Session`]: quinn_proto::crypto::Session
     /// [`downcast`]: Box::downcast
     #[inline]
-    pub fn peer_identity(&self) -> Option<Box<dyn Any>> {
-        self.inner.peer_identity()
+    pub fn peer_identity(&self) -> Box<dyn Any> {
+        self.inner
+            .peer_identity()
+            .expect("we always have a peer identity")
     }
 
     /// Returns the [`NodeId`] from the peer's TLS certificate.
@@ -1545,25 +1579,14 @@ impl Connection {
     /// connection.
     ///
     /// [`PublicKey`]: iroh_base::PublicKey
-    // TODO: Would be nice if this could be infallible.
-    pub fn remote_node_id(&self) -> Result<NodeId> {
+    pub fn remote_node_id(&self) -> NodeId {
         let data = self.peer_identity();
-        match data {
-            None => bail!("no peer certificate found"),
-            Some(data) => match data.downcast::<Vec<rustls::pki_types::CertificateDer>>() {
-                Ok(certs) => {
-                    if certs.len() != 1 {
-                        bail!(
-                            "expected a single peer certificate, but {} found",
-                            certs.len()
-                        );
-                    }
-                    let cert = tls::certificate::parse(&certs[0])?;
-                    Ok(cert.peer_id())
-                }
-                Err(_) => bail!("invalid peer certificate"),
-            },
-        }
+        let certs = data
+            .downcast::<Vec<rustls::pki_types::CertificateDer>>()
+            .expect("we always have a cert");
+        debug_assert_eq!(certs.len(), 1);
+        let cert = tls::certificate::parse(&certs[0]).expect("valid cert");
+        cert.peer_id()
     }
 
     /// A stable identifier for this connection.
@@ -1624,10 +1647,7 @@ impl Connection {
 /// function.
 fn try_send_rtt_msg(conn: &Connection, magic_ep: &Endpoint) {
     // If we can't notify the rtt-actor that's not great but not critical.
-    let Ok(node_id) = conn.remote_node_id() else {
-        warn!(?conn, "failed to get remote node id");
-        return;
-    };
+    let node_id = conn.remote_node_id();
     let Ok(conn_type_changes) = magic_ep.conn_type(node_id) else {
         warn!(?conn, "failed to create conn_type stream");
         return;
@@ -1953,7 +1973,7 @@ mod tests {
                         info!("[server] round {i}");
                         let incoming = ep.accept().await.unwrap();
                         let conn = incoming.await.unwrap();
-                        let node_id = conn.remote_node_id().unwrap();
+                        let node_id = conn.remote_node_id();
                         info!(%i, peer = %node_id.fmt_short(), "accepted connection");
                         let (mut send, mut recv) = conn.accept_bi().await.unwrap();
                         let mut buf = vec![0u8; chunk_size];
@@ -2066,10 +2086,10 @@ mod tests {
 
         async fn accept_world(ep: Endpoint, src: NodeId) {
             let incoming = ep.accept().await.unwrap();
-            let mut iconn = incoming.accept().unwrap();
-            let alpn = iconn.alpn().await.unwrap();
+            let iconn = incoming.accept().unwrap();
             let conn = iconn.await.unwrap();
-            let node_id = conn.remote_node_id().unwrap();
+            let alpn = conn.alpn();
+            let node_id = conn.remote_node_id();
             assert_eq!(node_id, src);
             assert_eq!(alpn, TEST_ALPN);
             let (mut send, mut recv) = conn.accept_bi().await.unwrap();
@@ -2159,7 +2179,7 @@ mod tests {
         async fn accept(ep: &Endpoint) -> NodeId {
             let incoming = ep.accept().await.unwrap();
             let conn = incoming.await.unwrap();
-            let node_id = conn.remote_node_id().unwrap();
+            let node_id = conn.remote_node_id();
             tracing::info!(node_id=%node_id.fmt_short(), "accepted connection");
             node_id
         }