Implement get and set tunnel config actions

Add three tunnel actions:
com.wireguard.android.action.GET_TUNNEL_CONFIG
com.wireguard.android.action.SET_TUNNEL_CONFIG
com.wireguard.android.action.SET_TUNNEL_USERSPACE_CONFIG

6 files changed, 104 insertions, 0 deletions

diff --git a/tunnel/src/main/java/com/wireguard/android/backend/Backend.java b/tunnel/src/main/java/com/wireguard/android/backend/Backend.java
index 5aaad826..45cd73e5 100644
--- a/tunnel/src/main/java/com/wireguard/android/backend/Backend.java
+++ b/tunnel/src/main/java/com/wireguard/android/backend/Backend.java
@@ -19,6 +19,17 @@ import androidx.annotation.Nullable;
 @NonNullForAll
 public interface Backend {
     /**
+     * Update the volatile configuration of a running tunnel and return the resulting configuration.
+     * If the tunnel is not up, return the configuration that would result (if known), or else
+     * simply return the given configuration.
+     *
+     * @param tunnel The tunnel to apply the configuration to.
+     * @param config The new configuration for this tunnel.
+     * @return The updated configuration of the tunnel.
+     */
+    Config applyUserspaceConfig(ObservableTunnel tunnel, Config config) throws Exception;
+
+    /**
      * Enumerate names of currently-running tunnels.
      *
      * @return The set of running tunnel names.
diff --git a/tunnel/src/main/java/com/wireguard/android/backend/GoBackend.java b/tunnel/src/main/java/com/wireguard/android/backend/GoBackend.java
index 3d0886cf..21c449b9 100644
--- a/tunnel/src/main/java/com/wireguard/android/backend/GoBackend.java
+++ b/tunnel/src/main/java/com/wireguard/android/backend/GoBackend.java
@@ -80,6 +80,10 @@ public final class GoBackend implements Backend {
 
     private static native int wgTurnOn(String ifName, int tunFd, String settings);
 
+    private static native String wgGetOperation(int handle);
+
+    private static native int wgSetOperation(int handle, String settings);
+
     private static native String wgVersion();
 
     /**
@@ -88,6 +92,19 @@ public final class GoBackend implements Backend {
      * @return A set of string values denoting names of running tunnels.
      */
     @Override
+    public Config applyUserspaceConfig(final ObservableTunnel tunnel, final Config config) throws Exception {
+        if (currentTunnelHandle != -1) {
+            // Build config
+            final String goConfig = config.toWgUserspaceString();
+
+            Log.d(TAG, "Go backend v" + wgVersion());
+            wgSetOperation(currentTunnelHandle, goConfig);
+            Log.d(TAG, "Settings " + wgGetOperation(currentTunnelHandle));
+        }
+        return config;
+    }
+
+    @Override
     public Set<String> getRunningTunnelNames() {
         if (currentTunnel != null) {
             final Set<String> runningTunnels = new ArraySet<>();
@@ -305,6 +322,7 @@ public final class GoBackend implements Backend {
                     throw new BackendException(Reason.TUN_CREATION_ERROR);
                 Log.d(TAG, "Go backend " + wgVersion());
                 currentTunnelHandle = wgTurnOn(tunnel.getName(), tun.detachFd(), goConfig);
+                Log.d(TAG, "Settings " + wgGetOperation(currentTunnelHandle));
             }
             if (currentTunnelHandle < 0)
                 throw new BackendException(Reason.GO_ACTIVATION_ERROR_CODE, currentTunnelHandle);
diff --git a/tunnel/src/main/java/com/wireguard/android/backend/WgQuickBackend.java b/tunnel/src/main/java/com/wireguard/android/backend/WgQuickBackend.java
index 3121c996..f07a662c 100644
--- a/tunnel/src/main/java/com/wireguard/android/backend/WgQuickBackend.java
+++ b/tunnel/src/main/java/com/wireguard/android/backend/WgQuickBackend.java
@@ -58,6 +58,11 @@ public final class WgQuickBackend implements Backend {
     }
 
     @Override
+    public Config applyUserspaceConfig(final ObservableTunnel tunnel, final Config config) throws Exception {
+        throw new RuntimeException("Not implemented");
+    }
+
+    @Override
     public Set<String> getRunningTunnelNames() {
         final List<String> output = new ArrayList<>();
         // Don't throw an exception here or nothing will show up in the UI.
diff --git a/tunnel/tools/libwg-go/api-android.go b/tunnel/tools/libwg-go/api-android.go
index 94d07c39..6c65ae10 100644
--- a/tunnel/tools/libwg-go/api-android.go
+++ b/tunnel/tools/libwg-go/api-android.go
@@ -10,7 +10,15 @@ package main
 import "C"
 
 import (
+	"bufio"
+	"bytes"
 	"fmt"
+	"golang.org/x/sys/unix"
+	"golang.zx2c4.com/wireguard/device"
+	"golang.zx2c4.com/wireguard/ipc"
+	"golang.zx2c4.com/wireguard/tun"
+	"bytes"
+	"log"
 	"math"
 	"net"
 	"os"
@@ -159,6 +167,40 @@ func wgTurnOff(tunnelHandle int32) {
 	handle.device.Close()
 }
 
+//export wgGetOperation
+func wgGetOperation(tunnelHandle int32) *C.char {
+	handle, ok := tunnelHandles[tunnelHandle]
+	if !ok {
+		return C.CString("(bad handle)")
+	}
+
+	var buf bytes.Buffer
+	writer := bufio.NewWriter(&buf)
+
+	getError := handle.device.IpcGetOperation(writer)
+	if getError != nil {
+		return C.CString(getError.Error())
+	}
+
+	writer.Flush()
+	return C.CString(buf.String())
+}
+
+//export wgSetOperation
+func wgSetOperation(tunnelHandle int32, settings string) int32 {
+	handle, ok := tunnelHandles[tunnelHandle]
+	if !ok {
+		return -1
+	}
+
+	setError := handle.device.IpcSetOperation(bufio.NewReader(strings.NewReader(settings)))
+	if setError != nil {
+		return -1
+	}
+
+	return 0
+}
+
 //export wgGetSocketV4
 func wgGetSocketV4(tunnelHandle int32) int32 {
 	handle, ok := tunnelHandles[tunnelHandle]
diff --git a/tunnel/tools/libwg-go/jni.c b/tunnel/tools/libwg-go/jni.c
index 7ad94d35..6444c235 100644
--- a/tunnel/tools/libwg-go/jni.c
+++ b/tunnel/tools/libwg-go/jni.c
@@ -10,6 +10,8 @@
 struct go_string { const char *str; long n; };
 extern int wgTurnOn(struct go_string ifname, int tun_fd, struct go_string settings);
 extern void wgTurnOff(int handle);
+extern char *wgGetOperation(int handle);
+extern int wgSetOperation(int handle, struct go_string settings);
 extern int wgGetSocketV4(int handle);
 extern int wgGetSocketV6(int handle);
 extern char *wgGetConfig(int handle);
@@ -38,6 +40,29 @@ JNIEXPORT void JNICALL Java_com_wireguard_android_backend_GoBackend_wgTurnOff(JN
 	wgTurnOff(handle);
 }
 
+JNIEXPORT jstring JNICALL Java_com_wireguard_android_backend_GoBackend_wgGetOperation(JNIEnv *env, jclass c, jint handle)
+{
+	jstring ret;
+	char *settings = wgGetOperation(handle);
+	if (!settings)
+		return NULL;
+	ret = (*env)->NewStringUTF(env, settings);
+	free(settings);
+	return ret;
+}
+
+JNIEXPORT jint JNICALL Java_com_wireguard_android_backend_GoBackend_wgSetOperation(JNIEnv *env, jclass c, jint handle, jstring settings)
+{
+	const char *settings_str = (*env)->GetStringUTFChars(env, settings, 0);
+	size_t settings_len = (*env)->GetStringUTFLength(env, settings);
+	int ret = wgSetOperation(handle, (struct go_string){
+		.str = settings_str,
+		.n = settings_len
+	});
+	(*env)->ReleaseStringUTFChars(env, settings, settings_str);
+	return ret;
+}
+
 JNIEXPORT jint JNICALL Java_com_wireguard_android_backend_GoBackend_wgGetSocketV4(JNIEnv *env, jclass c, jint handle)
 {
 	return wgGetSocketV4(handle);
diff --git a/ui/src/main/AndroidManifest.xml b/ui/src/main/AndroidManifest.xml
index 4dd38cb2..744e451f 100644
--- a/ui/src/main/AndroidManifest.xml
+++ b/ui/src/main/AndroidManifest.xml
@@ -108,6 +108,9 @@
                 <action android:name="com.wireguard.android.action.REFRESH_TUNNEL_STATES" />
                 <action android:name="com.wireguard.android.action.SET_TUNNEL_UP" />
                 <action android:name="com.wireguard.android.action.SET_TUNNEL_DOWN" />
+                <action android:name="com.wireguard.android.action.GET_TUNNEL_CONFIG" />
+                <action android:name="com.wireguard.android.action.SET_TUNNEL_CONFIG" />
+                <action android:name="com.wireguard.android.action.SET_TUNNEL_USERSPACE_CONFIG" />
             </intent-filter>
         </receiver>