From 11505a5c05f3489053ec00c01717b755255f3a2c Mon Sep 17 00:00:00 2001
From: Alireza Ahmadi <alireza7@gmail.com>
Date: Sun, 22 Mar 2026 18:39:23 +0100
Subject: [PATCH] simplify conn tracker #1056

---
 core/box.go          |  8 ++---
 core/main.go         |  2 --
 core/tracker_conn.go | 81 ++++++++++++++++++++++++++++++++++++++++----
 3 files changed, 77 insertions(+), 14 deletions(-)

diff --git a/core/box.go b/core/box.go
index aa91b7f..f9797f8 100644
--- a/core/box.go
+++ b/core/box.go
@@ -326,13 +326,9 @@ func NewBox(options Options) (*Box, error) {
 			return nil, common.NewError("initialize platform interface", err)
 		}
 	}
-	if statsTracker == nil {
-		statsTracker = NewStatsTracker()
-	}
+	statsTracker := NewStatsTracker()
+	connTracker := NewConnTracker()
 	router.AppendTracker(statsTracker)
-	if connTracker == nil {
-		connTracker = NewConnTracker()
-	}
 	router.AppendTracker(connTracker)
 
 	if needCacheFile {
diff --git a/core/main.go b/core/main.go
index e43eb94..61aad08 100644
--- a/core/main.go
+++ b/core/main.go
@@ -22,8 +22,6 @@ var (
 	service_manager  adapter.ServiceManager
 	endpoint_manager adapter.EndpointManager
 	router           adapter.Router
-	statsTracker     *StatsTracker
-	connTracker      *ConnTracker
 	factory          log.Factory
 )
 
diff --git a/core/tracker_conn.go b/core/tracker_conn.go
index 2bd3384..626715f 100644
--- a/core/tracker_conn.go
+++ b/core/tracker_conn.go
@@ -2,11 +2,15 @@ package core
 
 import (
 	"context"
+	"errors"
+	"io"
 	"net"
 	"sync"
 
 	"github.com/gofrs/uuid/v5"
 	"github.com/sagernet/sing-box/adapter"
+	"github.com/sagernet/sing/common/buf"
+	M "github.com/sagernet/sing/common/metadata"
 	"github.com/sagernet/sing/common/network"
 )
 
@@ -107,27 +111,68 @@ func (c *ConnTracker) untrackConnection(connID string) {
 	delete(c.connections, connID)
 }
 
+// shouldUntrackIOErr reports whether err indicates the connection is done (peer closed, reset, etc.).
+func shouldUntrackIOErr(err error) bool {
+	if err == nil {
+		return false
+	}
+	if errors.Is(err, io.EOF) {
+		return true
+	}
+	var ne net.Error
+	if errors.As(err, &ne) {
+		return !ne.Temporary()
+	}
+	return true
+}
+
 func (c *ConnTracker) createWrappedConn(conn net.Conn, connID string) *wrappedConn {
 	return &wrappedConn{
-		Conn:   conn,
-		connID: connID,
+		Conn:    conn,
+		tracker: c,
+		connID:  connID,
 	}
 }
 
 func (c *ConnTracker) createWrappedPacketConn(conn network.PacketConn, connID string) *wrappedPacketConn {
 	return &wrappedPacketConn{
 		PacketConn: conn,
+		tracker:    c,
 		connID:     connID,
 	}
 }
 
 type wrappedConn struct {
 	net.Conn
-	connID string
+	tracker     *ConnTracker
+	connID      string
+	untrackOnce sync.Once
+}
+
+func (w *wrappedConn) doUntrack() {
+	w.untrackOnce.Do(func() {
+		w.tracker.untrackConnection(w.connID)
+	})
+}
+
+func (w *wrappedConn) Read(b []byte) (int, error) {
+	n, err := w.Conn.Read(b)
+	if shouldUntrackIOErr(err) {
+		w.doUntrack()
+	}
+	return n, err
+}
+
+func (w *wrappedConn) Write(b []byte) (int, error) {
+	n, err := w.Conn.Write(b)
+	if err != nil && shouldUntrackIOErr(err) {
+		w.doUntrack()
+	}
+	return n, err
 }
 
 func (w *wrappedConn) Close() error {
-	connTracker.untrackConnection(w.connID)
+	w.doUntrack()
 	return w.Conn.Close()
 }
 
@@ -137,11 +182,35 @@ func (w *wrappedConn) Upstream() any {
 
 type wrappedPacketConn struct {
 	network.PacketConn
-	connID string
+	tracker     *ConnTracker
+	connID      string
+	untrackOnce sync.Once
+}
+
+func (w *wrappedPacketConn) doUntrack() {
+	w.untrackOnce.Do(func() {
+		w.tracker.untrackConnection(w.connID)
+	})
+}
+
+func (w *wrappedPacketConn) ReadPacket(buffer *buf.Buffer) (destination M.Socksaddr, err error) {
+	dest, err := w.PacketConn.ReadPacket(buffer)
+	if shouldUntrackIOErr(err) {
+		w.doUntrack()
+	}
+	return dest, err
+}
+
+func (w *wrappedPacketConn) WritePacket(buffer *buf.Buffer, destination M.Socksaddr) error {
+	err := w.PacketConn.WritePacket(buffer, destination)
+	if err != nil && shouldUntrackIOErr(err) {
+		w.doUntrack()
+	}
+	return err
 }
 
 func (w *wrappedPacketConn) Close() error {
-	connTracker.untrackConnection(w.connID)
+	w.doUntrack()
 	return w.PacketConn.Close()
 }