allow base conn of TLS conn to be tagged

Author: Snawoot

main.go

@@ -785,6 +785,7 @@ func run() int {
 			mainLogger.Critical("TLS config construction failed: %v", err1)
 			return 3
 		}
+		listener = tlsutil.NewTaggedConnListener(listener) // attach DTO container
 		listener = tls.NewListener(listener, cfg)
 	} else if args.autocert {
 		// cert caching chain
@@ -850,6 +851,7 @@ func run() int {
 		if len(cfg.NextProtos) > 0 {
 			cfg.NextProtos = append(cfg.NextProtos, acme.ALPNProto)
 		}
+		listener = tlsutil.NewTaggedConnListener(listener) // attach DTO container
 		listener = tls.NewListener(listener, cfg)
 	}
 	defer listener.Close()

tlsutil/taggedconn.go

@@ -0,0 +1,65 @@
+package tlsutil
+
+import (
+	"net"
+	"sync"
+)
+
+type ConnTagger interface {
+	GetTag(any) (any, bool)
+	SetTag(any, any)
+}
+
+type TaggedConn struct {
+	net.Conn
+	mux  sync.RWMutex
+	tags map[any]any
+}
+
+func (c *TaggedConn) SetTag(key, value any) {
+	c.mux.Lock()
+	defer c.mux.Unlock()
+	if c.tags == nil {
+		c.tags = make(map[any]any)
+	}
+	c.tags[key] = value
+}
+
+func (c *TaggedConn) GetTag(key any) (any, bool) {
+	c.mux.RLock()
+	defer c.mux.RUnlock()
+	value, ok := c.tags[key]
+	return value, ok
+}
+
+func NewTaggedConn(conn net.Conn) *TaggedConn {
+	return &TaggedConn{
+		Conn: conn,
+	}
+}
+
+type TaggedConnListener struct {
+	net.Listener
+}
+
+func (l TaggedConnListener) Accept() (net.Conn, error) {
+	conn, err := l.Listener.Accept()
+	if err != nil {
+		return nil, err
+	}
+	_, ok := conn.(ConnTagger)
+	if ok {
+		return conn, nil
+	}
+	return NewTaggedConn(conn), nil
+}
+
+func NewTaggedConnListener(l net.Listener) TaggedConnListener {
+	return TaggedConnListener{
+		Listener: l,
+	}
+}
+
+var _ net.Conn = new(TaggedConn)
+var _ net.Listener = TaggedConnListener{}
+var _ ConnTagger = new(TaggedConn)