Add SO_REUSEPORT support for EntryPoints

pkg/udp/conn.go

@@ -1,7 +1,9 @@
 package udp
 
 import (
+	"context"
 	"errors"
+	"fmt"
 	"io"
 	"net"
 	"sync"
@@ -33,18 +35,22 @@ type Listener struct {
 }
 
 // Listen creates a new listener.
-func Listen(network string, laddr *net.UDPAddr, timeout time.Duration) (*Listener, error) {
+func Listen(listenConfig net.ListenConfig, network, address string, timeout time.Duration) (*Listener, error) {
 	if timeout <= 0 {
 		return nil, errors.New("timeout should be greater than zero")
 	}
 
-	conn, err := net.ListenUDP(network, laddr)
+	packetConn, err := listenConfig.ListenPacket(context.Background(), network, address)
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("listen packet: %w", err)
+	}
+	pConn, ok := packetConn.(*net.UDPConn)
+	if !ok {
+		return nil, errors.New("packet conn is not an UDPConn")
 	}
 
 	l := &Listener{
-		pConn:     conn,
+		pConn:     pConn,
 		acceptCh:  make(chan *Conn),
 		conns:     make(map[string]*Conn),
 		accepting: true,