conn_listener: Refactor with sync

handler/conn_listener.go

@@ -3,6 +3,7 @@ package handler
 import (
 	"errors"
 	"net"
+	"sync"
 )
 
 var ErrNetClosing = errors.New("use of closed network connection")
@@ -11,6 +12,8 @@ type ConnListener struct {
 	isClosed bool
 	connChan chan net.Conn
 	exitChan chan struct{}
+	mu       sync.Mutex
+	once     sync.Once
 }
 
 func NewConnListener() *ConnListener {
@@ -33,21 +36,26 @@ func (c *ConnListener) Accept() (net.Conn, error) {
 }
 
 func (c *ConnListener) Close() error {
-	if c.isClosed {
-		return ErrNetClosing
-	}
-	c.isClosed = true
-	c.exitChan <- struct{}{}
-	close(c.exitChan)
-	close(c.connChan)
+	c.once.Do(func() {
+		c.mu.Lock()
+		defer c.mu.Unlock()
+		if c.isClosed {
+			return
+		}
+		c.isClosed = true
+		close(c.exitChan)
+		close(c.connChan)
+	})
 	return nil
 }
 
 func (c *ConnListener) Addr() net.Addr {
-	return nil
+	return &net.TCPAddr{IP: net.IPv4zero, Port: 0}
 }
 
 func (c *ConnListener) HandleConn(conn net.Conn) error {
+	c.mu.Lock()
+	defer c.mu.Unlock()
 	if c.isClosed {
 		return ErrNetClosing
 	}