From 761645b20acaf5066af62190e6adcb344c64110f Mon Sep 17 00:00:00 2001
From: Aliaksandr Valialkin <valyala@gmail.com>
Date: Sun, 1 Dec 2019 02:52:22 +0200
Subject: [PATCH] lib/netutil: use IPv6 for both listening and dialing if
 `-enabledTCP6` is set

Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/244
---
 lib/netutil/tcplistener.go | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/lib/netutil/tcplistener.go b/lib/netutil/tcplistener.go
index e1666348e5..31d3ae40e9 100644
--- a/lib/netutil/tcplistener.go
+++ b/lib/netutil/tcplistener.go
@@ -9,18 +9,14 @@ import (
 	"github.com/VictoriaMetrics/metrics"
 )
 
-var enableTCP6 = flag.Bool("enableTCP6", false, "Whether to enable listening for IPv6 TCP ports. By default only IPv4 TCP ports are listened")
+var enableTCP6 = flag.Bool("enableTCP6", false, "Whether to enable IPv6 for listening and dialing. By default only IPv4 TCP is used")
 
 // NewTCPListener returns new TCP listener for the given addr.
 //
 // name is used for exported metrics. Each listener in the program must have
 // distinct name.
 func NewTCPListener(name, addr string) (*TCPListener, error) {
-	network := "tcp4"
-	if *enableTCP6 {
-		// Enable listening on both tcp4 and tcp6
-		network = "tcp"
-	}
+	network := getNetwork()
 	ln, err := net.Listen(network, addr)
 	if err != nil {
 		return nil, err
@@ -35,6 +31,14 @@ func NewTCPListener(name, addr string) (*TCPListener, error) {
 	return tln, err
 }
 
+func getNetwork() string {
+	if *enableTCP6 {
+		// Enable both tcp4 and tcp6
+		return "tcp"
+	}
+	return "tcp4"
+}
+
 // TCPListener listens for the addr passed to NewTCPListener.
 //
 // It also gathers various stats for the accepted connections.