From c718f3940d6546f83cc14c4f121d52470a705c31 Mon Sep 17 00:00:00 2001
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: Fri, 17 May 2019 15:35:20 +0200
Subject: [PATCH] device: fail to give bind if it doesn't exist

---
 device/boundif_android.go | 14 ++++++++++++--
 device/device.go          |  1 +
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/device/boundif_android.go b/device/boundif_android.go
index ecc9331..6d0fecf 100644
--- a/device/boundif_android.go
+++ b/device/boundif_android.go
@@ -5,8 +5,14 @@
 
 package device
 
+import "errors"
+
 func (device *Device) PeekLookAtSocketFd4() (fd int, err error) {
-	sysconn, err := device.net.bind.(*nativeBind).ipv4.SyscallConn()
+	nb, ok := device.net.bind.(*nativeBind)
+	if !ok {
+		return 0, errors.New("no socket exists")
+	}
+	sysconn, err := nb.ipv4.SyscallConn()
 	if err != nil {
 		return
 	}
@@ -20,7 +26,11 @@ func (device *Device) PeekLookAtSocketFd4() (fd int, err error) {
 }
 
 func (device *Device) PeekLookAtSocketFd6() (fd int, err error) {
-	sysconn, err := device.net.bind.(*nativeBind).ipv6.SyscallConn()
+	nb, ok := device.net.bind.(*nativeBind)
+	if !ok {
+		return 0, errors.New("no socket exists")
+	}
+	sysconn, err := nb.ipv6.SyscallConn()
 	if err != nil {
 		return
 	}
diff --git a/device/device.go b/device/device.go
index ef269f5..fa7ed88 100644
--- a/device/device.go
+++ b/device/device.go
@@ -133,6 +133,7 @@ func deviceUpdateState(device *Device) {
 	switch newIsUp {
 	case true:
 		if err := device.BindUpdate(); err != nil {
+			device.log.Error.Printf("Unable to update bind: %v\n", err)
 			device.isUp.Set(false)
 			break
 		}