package conntrack import ( "io" "net" "github.com/sagernet/sing/common/x/list" ) type PacketConn struct { net.PacketConn element *list.Element[io.Closer] } func NewPacketConn(conn net.PacketConn) (net.PacketConn, error) { connAccess.Lock() element := openConnection.PushBack(conn) connAccess.Unlock() if KillerEnabled { err := killerCheck() if err != nil { conn.Close() return nil, err } } return &PacketConn{ PacketConn: conn, element: element, }, nil } func (c *PacketConn) Close() error { if c.element.Value != nil { connAccess.Lock() if c.element.Value != nil { openConnection.Remove(c.element) c.element.Value = nil } connAccess.Unlock() } return c.PacketConn.Close() } func (c *PacketConn) Upstream() any { return c.PacketConn } func (c *PacketConn) ReaderReplaceable() bool { return true } func (c *PacketConn) WriterReplaceable() bool { return true }