From 28c7eb43358df44ab010f6b7ace2849647d9126c Mon Sep 17 00:00:00 2001
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: Mon, 14 May 2018 19:23:44 +0200
Subject: [PATCH] Print utun name on darwin

---
 allowedips.go | 2 +-
 tun_darwin.go | 6 +++++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/allowedips.go b/allowedips.go
index 5b1565e..92a6f1d 100644
--- a/allowedips.go
+++ b/allowedips.go
@@ -184,7 +184,7 @@ func (node *trieEntry) entriesForPeer(p *Peer, results []net.IPNet) []net.IPNet
 		mask := net.CIDRMask(int(node.cidr), len(node.bits)*8)
 		results = append(results, net.IPNet{
 			Mask: mask,
-			IP: node.bits.Mask(mask),
+			IP:   node.bits.Mask(mask),
 		})
 	}
 	results = node.child[0].entriesForPeer(p, results)
diff --git a/tun_darwin.go b/tun_darwin.go
index 8f9a5d5..ed055b2 100644
--- a/tun_darwin.go
+++ b/tun_darwin.go
@@ -12,6 +12,7 @@ import (
 	"fmt"
 	"golang.org/x/net/ipv6"
 	"golang.org/x/sys/unix"
+	"io/ioutil"
 	"net"
 	"os"
 	"time"
@@ -104,7 +105,10 @@ func CreateTUN(name string) (TUNDevice, error) {
 	tun, err := CreateTUNFromFile(os.NewFile(uintptr(fd), ""))
 
 	if err == nil && name == "utun" {
-		fmt.Printf("OS assigned interface: %s\n", tun.(*NativeTun).name)
+		fname := os.Getenv("WG_DARWIN_UTUN_NAME_FILE")
+		if fname != "" {
+			ioutil.WriteFile(fname, []byte(tun.(*NativeTun).name+"\n"), 0400)
+		}
 	}
 
 	return tun, err