android: Implement kernel_net_t.get_interface via JNI

This is now required to properly accept/install a virtual IP address.

Fixes #275.

src/frontends/android/jni/libandroidbridge/kernel/android_net.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2012 Tobias Brunner
+ * Copyright (C) 2012-2013 Tobias Brunner
  * Hochschule fuer Technik Rapperswil
  *
  * This program is free software; you can redistribute it and/or modify it
@@ -91,6 +91,13 @@ METHOD(kernel_net_t, get_source_addr, host_t*,
 											dest->get_family(dest) == AF_INET);
 }
 
+METHOD(kernel_net_t, get_interface, bool,
+	private_kernel_android_net_t *this, host_t *host, char **name)
+{
+	return this->network_manager->get_interface(this->network_manager, host,
+												name);
+}
+
 METHOD(kernel_net_t, add_ip, status_t,
 	private_kernel_android_net_t *this, host_t *virtual_ip, int prefix,
 	char *iface)
@@ -120,7 +127,7 @@ kernel_android_net_t *kernel_android_net_create()
 			.interface = {
 				.get_source_addr = _get_source_addr,
 				.get_nexthop = (void*)return_null,
-				.get_interface = (void*)return_null,
+				.get_interface = _get_interface,
 				.create_address_enumerator = (void*)enumerator_create_empty,
 				.add_ip = _add_ip,
 				.del_ip = (void*)return_failed,

src/frontends/android/jni/libandroidbridge/kernel/network_manager.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2012 Tobias Brunner
+ * Copyright (C) 2012-2013 Tobias Brunner
  * Hochschule fuer Technik Rapperswil
  *
  * This program is free software; you can redistribute it and/or modify it
@@ -69,7 +69,7 @@ METHOD(network_manager_t, get_local_address, host_t*,
 		goto failed;
 	}
 	jaddr = (*env)->CallObjectMethod(env, this->obj, method_id, ipv4);
-	if (!jaddr)
+	if (!jaddr || androidjni_exception_occurred(env))
 	{
 		goto failed;
 	}
@@ -85,6 +85,46 @@ failed:
 	return NULL;
 }
 
+METHOD(network_manager_t, get_interface, bool,
+	private_network_manager_t *this, host_t *ip, char **name)
+{
+	JNIEnv *env;
+	jmethodID method_id;
+	jbyteArray jaddr;
+	jstring jinterface;
+
+	if (ip->is_anyaddr(ip))
+	{
+		return FALSE;
+	}
+
+	androidjni_attach_thread(&env);
+
+	method_id = (*env)->GetMethodID(env, this->cls, "getInterface",
+									"([B)Ljava/lang/String;");
+	if (!method_id)
+	{
+		goto failed;
+	}
+	jaddr = byte_array_from_chunk(env, ip->get_address(ip));
+	jinterface = (*env)->CallObjectMethod(env, this->obj, method_id, jaddr);
+	if (!jinterface || androidjni_exception_occurred(env))
+	{
+		goto failed;
+	}
+	if (name)
+	{
+		*name = androidjni_convert_jstring(env, jinterface);
+	}
+	androidjni_detach_thread();
+	return TRUE;
+
+failed:
+	androidjni_exception_occurred(env);
+	androidjni_detach_thread();
+	return FALSE;
+}
+
 JNI_METHOD(NetworkManager, networkChanged, void,
 	bool disconnected)
 {
@@ -206,6 +246,7 @@ network_manager_t *network_manager_create(jobject context)
 	INIT(this,
 		.public = {
 			.get_local_address = _get_local_address,
+			.get_interface = _get_interface,
 			.add_connectivity_cb = _add_connectivity_cb,
 			.remove_connectivity_cb = _remove_connectivity_cb,
 			.destroy = _destroy,

src/frontends/android/jni/libandroidbridge/kernel/network_manager.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2012 Tobias Brunner
+ * Copyright (C) 2012-2013 Tobias Brunner
  * Hochschule fuer Technik Rapperswil
  *
  * This program is free software; you can redistribute it and/or modify it
@@ -55,6 +55,15 @@ struct network_manager_t {
 	 */
 	host_t *(*get_local_address)(network_manager_t *this, bool ipv4);
 
+	/**
+	 * Get the name of the interface on which the given IP address is installed
+	 *
+	 * @param ip				the IP address to look for
+	 * @param name				returns the name of the interface (optional)
+	 * @return					TRUE if found
+	 */
+	bool (*get_interface)(network_manager_t *this, host_t *ip, char **name);
+
 	/**
 	 * Register a callback that is called if connectivity changes
 	 *

src/frontends/android/src/org/strongswan/android/logic/NetworkManager.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2012 Tobias Brunner
+ * Copyright (C) 2012-2013 Tobias Brunner
  * Hochschule fuer Technik Rapperswil
  *
  * This program is free software; you can redistribute it and/or modify it
@@ -20,6 +20,7 @@ import java.net.Inet6Address;
 import java.net.InetAddress;
 import java.net.NetworkInterface;
 import java.net.SocketException;
+import java.net.UnknownHostException;
 import java.util.Enumeration;
 
 import android.content.BroadcastReceiver;
@@ -110,4 +111,32 @@ public class NetworkManager extends BroadcastReceiver
 		}
 		return null;
 	}
+
+	/**
+	 * Search for an interface that has the given address installed.
+	 *
+	 * @param addr network-order byte encoding of the address to look for
+	 * @return name of the interface, or null if not found
+	 */
+	public String getInterface(byte[] addr)
+	{
+		try
+		{
+			InetAddress inetAddress = InetAddress.getByAddress(addr);
+			NetworkInterface intf = NetworkInterface.getByInetAddress(inetAddress);
+			if (intf != null)
+			{
+				return intf.getName();
+			}
+		}
+		catch (UnknownHostException e)
+		{
+			e.printStackTrace();
+		}
+		catch (SocketException e)
+		{
+			e.printStackTrace();
+		}
+		return null;
+	}
 }