conn: use local ipvN vars in StdNetBind.Open

This makes it clearer that they are fresh on each attempt,
and avoids the bookkeeping required to clearing them on failure.

Also, remove an unnecessary err != nil.

Signed-off-by: Josh Bleecher Snyder <josharian@gmail.com>

1 files changed, 9 insertions, 11 deletions

diff --git a/conn/bind_std.go b/conn/bind_std.go
index 73946b4..a511341 100644
--- a/conn/bind_std.go
+++ b/conn/bind_std.go
@@ -91,30 +91,28 @@ func (bind *StdNetBind) Open(uport uint16) (uint16, error) {
 
 again:
 	port := int(uport)
+	var ipv4, ipv6 *net.UDPConn
 
-	bind.ipv4, port, err = listenNet("udp4", port)
+	ipv4, port, err = listenNet("udp4", port)
 	if err != nil && !errors.Is(err, syscall.EAFNOSUPPORT) {
-		bind.ipv4 = nil
 		return 0, err
 	}
 
-	bind.ipv6, port, err = listenNet("udp6", port)
-	if uport == 0 && err != nil && errors.Is(err, syscall.EADDRINUSE) && tries < 100 {
-		bind.ipv4.Close()
-		bind.ipv4 = nil
-		bind.ipv6 = nil
+	ipv6, port, err = listenNet("udp6", port)
+	if uport == 0 && errors.Is(err, syscall.EADDRINUSE) && tries < 100 {
+		ipv4.Close()
 		tries++
 		goto again
 	}
 	if err != nil && !errors.Is(err, syscall.EAFNOSUPPORT) {
-		bind.ipv4.Close()
-		bind.ipv4 = nil
-		bind.ipv6 = nil
+		ipv4.Close()
 		return 0, err
 	}
-	if bind.ipv4 == nil && bind.ipv6 == nil {
+	if ipv4 == nil && ipv6 == nil {
 		return 0, syscall.EAFNOSUPPORT
 	}
+	bind.ipv4 = ipv4
+	bind.ipv6 = ipv6
 	return uint16(port), nil
 }