[client, relay] Expose relay transport and connection errors in status and metrics (#6342)

relay/server/listener/conn.go

@@ -11,4 +11,6 @@ type Conn interface {
 	Write(ctx context.Context, b []byte) (n int, err error)
 	RemoteAddr() net.Addr
 	Close() error
+	// Protocol returns the transport name.
+	Protocol() string
 }

relay/server/listener/quic/conn.go

@@ -42,6 +42,11 @@ func (c *Conn) RemoteAddr() net.Addr {
 	return c.session.RemoteAddr()
 }
 
+// Protocol returns the transport name for this connection.
+func (c *Conn) Protocol() string {
+	return "quic"
+}
+
 func (c *Conn) Close() error {
 	c.closedMu.Lock()
 	if c.closed {

relay/server/listener/ws/conn.go

@@ -64,6 +64,11 @@ func (c *Conn) RemoteAddr() net.Addr {
 	return c.rAddr
 }
 
+// Protocol returns the transport name for this connection.
+func (c *Conn) Protocol() string {
+	return "ws"
+}
+
 func (c *Conn) Close() error {
 	c.closedMu.Lock()
 	c.closed = true

relay/server/relay.go

@@ -154,15 +154,16 @@ func (r *Relay) Accept(conn listener.Conn) {
 	}
 	r.notifier.PeerCameOnline(peer.ID())
 
+	transport := conn.Protocol()
 	r.metrics.RecordPeerStoreTime(time.Since(storeTime))
-	r.metrics.PeerConnected(peer.String())
+	r.metrics.PeerConnected(peer.String(), transport)
 	go func() {
 		peer.Work()
 		if deleted := r.store.DeletePeer(peer); deleted {
 			r.notifier.PeerWentOffline(peer.ID())
 		}
 		peer.log.Debugf("relay connection closed")
-		r.metrics.PeerDisconnected(peer.String())
+		r.metrics.PeerDisconnected(peer.String(), transport)
 	}()
 
 	if err := h.handshakeResponse(hsCtx); err != nil {