From 80f22e6c3dc5075a777d90e311cf6658a4421a36 Mon Sep 17 00:00:00 2001
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: Wed, 18 Apr 2018 16:44:05 +0200
Subject: [PATCH] Determine MTU automatically

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 .../com/wireguard/android/backend/GoBackend.java     |  4 ++--
 app/tools/libwg-go/api-android.go                    | 12 +++++++++---
 app/tools/libwg-go/jni.c                             |  6 +++---
 app/tools/wireguard-go                               |  2 +-
 4 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/app/src/main/java/com/wireguard/android/backend/GoBackend.java b/app/src/main/java/com/wireguard/android/backend/GoBackend.java
index 5749bbc1..5331ad88 100644
--- a/app/src/main/java/com/wireguard/android/backend/GoBackend.java
+++ b/app/src/main/java/com/wireguard/android/backend/GoBackend.java
@@ -73,7 +73,7 @@ public final class GoBackend implements Backend {
 
     private static native void wgTurnOff(int handle);
 
-    private static native int wgTurnOn(String ifName, int tunFd, int mtu, String settings);
+    private static native int wgTurnOn(String ifName, int tunFd, String settings);
 
     @Override
     public Config applyConfig(final Tunnel tunnel, final Config config) throws Exception {
@@ -196,7 +196,7 @@ public final class GoBackend implements Backend {
             if (tun == null)
                 throw new Exception("Unable to create tun device");
 
-            currentTunnelHandle = wgTurnOn(tunnel.getName(), tun.detachFd(), mtu, fmt.toString());
+            currentTunnelHandle = wgTurnOn(tunnel.getName(), tun.detachFd(), fmt.toString());
             if (currentTunnelHandle < 0)
                 throw new Exception("Unable to turn tunnel on (wgTurnOn return " + currentTunnelHandle + ")");
 
diff --git a/app/tools/libwg-go/api-android.go b/app/tools/libwg-go/api-android.go
index 08367b9c..6b864bce 100644
--- a/app/tools/libwg-go/api-android.go
+++ b/app/tools/libwg-go/api-android.go
@@ -30,7 +30,7 @@ func init() {
 }
 
 //export wgTurnOn
-func wgTurnOn(ifnameRef string, tun_fd int32, mtu int32, settings string) int32 {
+func wgTurnOn(ifnameRef string, tun_fd int32, settings string) int32 {
 	interfaceName := string([]byte(ifnameRef))
 
 	logger := &Logger{
@@ -47,13 +47,19 @@ func wgTurnOn(ifnameRef string, tun_fd int32, mtu int32, settings string) int32
 		errors: make(chan error, 5),
 		nopi:   true,
 	}
+	name, err := tun.Name()
+	if err != nil {
+	    logger.Error.Println(err)
+	    return -1
+	}
+	logger.Info.Println("Attaching to interface", name)
 	device := NewDevice(tun, logger)
-	device.tun.mtu = mtu
+	logger.Debug.Println("Interface has MTU", device.tun.mtu)
 
 	bufferedSettings := bufio.NewReadWriter(bufio.NewReader(strings.NewReader(settings)), bufio.NewWriter(ioutil.Discard))
 	setError := ipcSetOperation(device, bufferedSettings)
 	if setError != nil {
-		logger.Debug.Println(setError)
+		logger.Error.Println(setError)
 		return -1
 	}
 
diff --git a/app/tools/libwg-go/jni.c b/app/tools/libwg-go/jni.c
index d32d64c4..1476dab7 100644
--- a/app/tools/libwg-go/jni.c
+++ b/app/tools/libwg-go/jni.c
@@ -1,12 +1,12 @@
 #include <jni.h>
 
 struct go_string { const char *str; long n; };
-extern int wgTurnOn(struct go_string ifname, int tun_fd, int mtu, struct go_string settings);
+extern int wgTurnOn(struct go_string ifname, int tun_fd, struct go_string settings);
 extern void wgTurnOff(int handle);
 extern int wgGetSocketV4(int handle);
 extern int wgGetSocketV6(int handle);
 
-JNIEXPORT jint JNICALL Java_com_wireguard_android_backend_GoBackend_wgTurnOn(JNIEnv *env, jclass c, jstring ifname, jint tun_fd, jint mtu, jstring settings)
+JNIEXPORT jint JNICALL Java_com_wireguard_android_backend_GoBackend_wgTurnOn(JNIEnv *env, jclass c, jstring ifname, jint tun_fd, jstring settings)
 {
 	const char *ifname_str = (*env)->GetStringUTFChars(env, ifname, 0);
 	size_t ifname_len = (*env)->GetStringUTFLength(env, ifname);
@@ -15,7 +15,7 @@ JNIEXPORT jint JNICALL Java_com_wireguard_android_backend_GoBackend_wgTurnOn(JNI
 	int ret = wgTurnOn((struct go_string){
 		.str = ifname_str,
 		.n = ifname_len
-	}, tun_fd, mtu, (struct go_string){
+	}, tun_fd, (struct go_string){
 		.str = settings_str,
 		.n = settings_len
 	});
diff --git a/app/tools/wireguard-go b/app/tools/wireguard-go
index c68acf44..26a56a65 160000
--- a/app/tools/wireguard-go
+++ b/app/tools/wireguard-go
@@ -1 +1 @@
-Subproject commit c68acf44c0e8874af66139bda7a8e1fc167fc6ea
+Subproject commit 26a56a652eeeece7677ba4f1896da34c83930652