conn: do not SO_REUSEADDR on linux

SO_REUSEADDR does not make sense for unicast UDP sockets.

Signed-off-by: Jason A. Donenfeld <[email protected]>

Author: zx2c4

conn/conn_linux.go

@@ -326,15 +326,6 @@ func create4(port uint16) (int, uint16, error) {
 	// set sockopts and bind
 
 	if err := func() error {
-		if err := unix.SetsockoptInt(
-			fd,
-			unix.SOL_SOCKET,
-			unix.SO_REUSEADDR,
-			1,
-		); err != nil {
-			return err
-		}
-
 		if err := unix.SetsockoptInt(
 			fd,
 			unix.IPPROTO_IP,
@@ -379,16 +370,6 @@ func create6(port uint16) (int, uint16, error) {
 	}
 
 	if err := func() error {
-
-		if err := unix.SetsockoptInt(
-			fd,
-			unix.SOL_SOCKET,
-			unix.SO_REUSEADDR,
-			1,
-		); err != nil {
-			return err
-		}
-
 		if err := unix.SetsockoptInt(
 			fd,
 			unix.IPPROTO_IPV6,