Fix: set SO_REUSEADDR for UDP listeners on linux (#630)

proxy/socks/udp.go

@@ -5,6 +5,7 @@ import (
 
 	adapters "github.com/Dreamacro/clash/adapters/inbound"
 	"github.com/Dreamacro/clash/common/pool"
+	"github.com/Dreamacro/clash/common/sockopt"
 	"github.com/Dreamacro/clash/component/socks5"
 	C "github.com/Dreamacro/clash/constant"
 	"github.com/Dreamacro/clash/tunnel"
@@ -22,6 +23,11 @@ func NewSocksUDPProxy(addr string) (*SockUDPListener, error) {
 		return nil, err
 	}
 
+	err = sockopt.UDPReuseaddr(l.(*net.UDPConn))
+	if err != nil {
+		return nil, err
+	}
+
 	sl := &SockUDPListener{l, addr, false}
 	go func() {
 		for {