bug: fix the potential UDP socket leaks for Windows client

client_windows.go

@@ -205,7 +205,7 @@ func (cli *Client) EnrollContext(nc net.Conn, ctx interface{}) (gc Conn, err err
 		c := newUDPConn(cli.el, nil, nc.LocalAddr(), nc.RemoteAddr())
 		c.SetContext(ctx)
 		c.rawConn = nc
-		cli.el.ch <- &openConn{c: c, isDatagram: true, cb: func() { close(connOpened) }}
+		cli.el.ch <- &openConn{c: c, cb: func() { close(connOpened) }}
 		go func(uc net.Conn, el *eventloop) {
 			var buffer [0x10000]byte
 			for {

connection_windows.go

@@ -45,7 +45,6 @@ type udpConn struct {
 type openConn struct {
 	c          *conn
 	cb         func()
-	isDatagram bool
 }
 
 type conn struct {

eventloop_unix.go

@@ -23,7 +23,6 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"net"
 	"os"
 	"strings"
 	"time"
@@ -232,33 +231,8 @@ func (el *eventloop) close(c *conn, err error) error {
 		return nil // ignore stale connections
 	}
 
-	action := el.eventHandler.OnClose(c, err)
-
-	var errStr strings.Builder
-
-	if _, ok := c.localAddr.(*net.UDPAddr); ok {
-		if err := el.poller.Delete(c.fd); err != nil {
-			err = fmt.Errorf("failed to delete fd=%d from poller in event-loop(%d): %v",
-				c.fd, el.idx, os.NewSyscallError("delete", err))
-			errStr.WriteString(err.Error())
-			errStr.WriteString(" | ")
-		}
-		if _, ok := el.listeners[c.fd]; !ok {
-			if err := unix.Close(c.fd); err != nil {
-				err = fmt.Errorf("failed to close fd=%d in event-loop(%d): %v",
-					c.fd, el.idx, os.NewSyscallError("close", err))
-				errStr.WriteString(err.Error())
-			}
-			el.connections.delConn(c)
-		}
-		c.release()
-		if errStr.Len() > 0 {
-			return errors.New(strings.TrimSuffix(errStr.String(), " | "))
-		}
-		return el.handleAction(c, action)
-	}
-
 	el.connections.delConn(c)
+	action := el.eventHandler.OnClose(c, err)
 
 	// Send residual data in buffer back to the remote before actually closing the connection.
 	for !c.outboundBuffer.IsEmpty() {
@@ -275,6 +249,7 @@ func (el *eventloop) close(c *conn, err error) error {
 
 	c.release()
 
+	var errStr strings.Builder
 	err0, err1 := el.poller.Delete(c.fd), unix.Close(c.fd)
 	if err0 != nil {
 		err0 = fmt.Errorf("failed to delete fd=%d from poller in event-loop(%d): %v",

eventloop_windows.go

@@ -18,7 +18,6 @@ import (
 	"bytes"
 	"context"
 	"errors"
-	"net"
 	"runtime"
 	"sync/atomic"
 	"time"
@@ -97,10 +96,8 @@ func (el *eventloop) open(oc *openConn) error {
 	}
 
 	c := oc.c
-	if !oc.isDatagram {
-		el.connections[c] = struct{}{}
-		el.incConn(1)
-	}
+	el.connections[c] = struct{}{}
+	el.incConn(1)
 
 	out, action := el.eventHandler.OnOpen(c)
 	if out != nil {
@@ -192,23 +189,14 @@ func (el *eventloop) close(c *conn, err error) error {
 		return nil // ignore stale wakes.
 	}
 
+	delete(el.connections, c)
+	el.incConn(-1)
 	action := el.eventHandler.OnClose(c, err)
 	err = nil
 
-	if _, ok := c.localAddr.(*net.UDPAddr); ok {
-		if c.rawConn != nil {
-			err = c.rawConn.Close()
-		}
-		c.release()
-		if err != nil {
-			return err
-		}
-		return el.handleAction(c, action)
+	if c.rawConn != nil {
+		err = c.rawConn.Close()
 	}
-
-	delete(el.connections, c)
-	el.incConn(-1)
-	err = c.rawConn.Close()
 	c.release()
 	if err != nil {
 		return err