Add bridge support

app/src/main/aidl/io/nekohasekai/sfa/bg/IBridgeSession.aidl

@@ -0,0 +1,11 @@
+package io.nekohasekai.sfa.bg;
+
+import android.os.ParcelFileDescriptor;
+
+interface IBridgeSession {
+    ParcelFileDescriptor getFileDescriptor();
+    String getName();
+    boolean isInet6Active();
+    void setEgress(String interfaceName);
+    void close();
+}

app/src/main/aidl/io/nekohasekai/sfa/bg/IRootService.aidl

@@ -1,6 +1,7 @@
 package io.nekohasekai.sfa.bg;
 
 import android.os.ParcelFileDescriptor;
+import io.nekohasekai.sfa.bg.IBridgeSession;
 import io.nekohasekai.sfa.bg.INeighborTableCallback;
 import io.nekohasekai.sfa.bg.IRootShellSession;
 import io.nekohasekai.sfa.bg.ParceledListSlice;
@@ -21,4 +22,6 @@ interface IRootService {
     IRootShellSession openShellSession(String user, String command, in String[] env, String term, int rows, int cols) = 6;
 
     String lookupSFTPServer() = 7;
+
+    IBridgeSession openBridge(String bridgeName, int mtu, String inet4Port, String inet6Port, int ruleIndex, int routeTable) = 8;
 }

app/src/main/java/io/nekohasekai/sfa/bg/PlatformInterfaceWrapper.kt

@@ -9,6 +9,8 @@ import android.provider.Settings
 import android.system.OsConstants
 import android.util.Log
 import androidx.annotation.RequiresApi
+import io.nekohasekai.libbox.BridgeOptions
+import io.nekohasekai.libbox.BridgeSession
 import io.nekohasekai.libbox.ConnectionOwner
 import io.nekohasekai.libbox.InterfaceUpdateListener
 import io.nekohasekai.libbox.Libbox
@@ -279,6 +281,25 @@ interface PlatformInterfaceWrapper : PlatformInterface {
     )?.takeIf { it.isNotBlank() }
         ?: "${Build.MANUFACTURER} ${Build.MODEL}"
 
+    override fun usePlatformBridge(): Boolean = RootClient.rootAvailable.value ?: runBlocking(Dispatchers.IO) {
+        RootClient.checkRootAvailable()
+    }
+
+    override fun createBridge(options: BridgeOptions?): BridgeSession {
+        options!!
+        val session = runBlocking(Dispatchers.IO) {
+            RootClient.openBridge(
+                options.bridgeName,
+                options.mtu,
+                options.inet4Port,
+                options.inet6Port,
+                options.ruleIndex,
+                options.routeTable,
+            )
+        }
+        return RootBridgeSessionWrapper(session)
+    }
+
     override fun lookupUser(username: String?): io.nekohasekai.libbox.PlatformUser {
         val resolved = UserResolver.resolve(Application.packageManager, username!!)
         val platformUser = io.nekohasekai.libbox.PlatformUser()
@@ -300,6 +321,24 @@ interface PlatformInterfaceWrapper : PlatformInterface {
         }
     }
 
+    private class RootBridgeSessionWrapper(
+        private val session: IBridgeSession,
+    ) : BridgeSession {
+        override fun fileDescriptor(): Int = session.fileDescriptor.detachFd()
+
+        override fun name(): String = session.name
+
+        override fun inet6Active(): Boolean = session.isInet6Active
+
+        override fun setEgress(interfaceName: String?) {
+            session.setEgress(interfaceName ?: "")
+        }
+
+        override fun close() {
+            session.close()
+        }
+    }
+
     private class RootShellSessionWrapper(
         private val rootSession: IRootShellSession,
     ) : ShellSession {

app/src/main/java/io/nekohasekai/sfa/bg/RootClient.kt

@@ -169,6 +169,22 @@ object RootClient {
         }
     }
 
+    suspend fun openBridge(
+        bridgeName: String,
+        mtu: Int,
+        inet4Port: String,
+        inet6Port: String,
+        ruleIndex: Int,
+        routeTable: Int,
+    ): IBridgeSession {
+        val svc = bindService()
+        try {
+            return svc.openBridge(bridgeName, mtu, inet4Port, inet6Port, ruleIndex, routeTable)
+        } catch (e: RemoteException) {
+            throw e.rethrowAsRuntime()
+        }
+    }
+
     suspend fun unregisterNeighborTableCallback(callback: INeighborTableCallback) {
         try {
             service?.unregisterNeighborTableCallback(callback)

app/src/main/java/io/nekohasekai/sfa/bg/RootServer.kt

@@ -9,6 +9,8 @@ import android.os.ParcelFileDescriptor
 import android.os.RemoteCallbackList
 import android.util.Log
 import com.topjohnwu.superuser.ipc.RootService
+import io.nekohasekai.libbox.BridgeOptions
+import io.nekohasekai.libbox.BridgeSession
 import io.nekohasekai.libbox.Libbox
 import io.nekohasekai.libbox.NeighborEntryIterator
 import io.nekohasekai.libbox.NeighborSubscription
@@ -36,6 +38,8 @@ class RootServer : RootService() {
     private var tetheringCallback: Any? = null
     private var tetheringManager: Any? = null
 
+    private val bridgeSessions = mutableSetOf<BridgeSessionBinder>()
+
     private val binder = object : IRootService.Stub() {
         override fun destroy() {
             stopSelf()
@@ -178,6 +182,29 @@ class RootServer : RootService() {
             return RootShellSession(session)
         }
 
+        override fun openBridge(
+            bridgeName: String?,
+            mtu: Int,
+            inet4Port: String?,
+            inet6Port: String?,
+            ruleIndex: Int,
+            routeTable: Int,
+        ): IBridgeSession {
+            val options = BridgeOptions()
+            options.bridgeName = bridgeName ?: ""
+            options.mtu = mtu
+            options.inet4Port = inet4Port ?: ""
+            options.inet6Port = inet6Port ?: ""
+            options.ruleIndex = ruleIndex
+            options.routeTable = routeTable
+            val session = Libbox.newBridgeService(options)
+            val binder = BridgeSessionBinder(session)
+            synchronized(bridgeSessions) {
+                bridgeSessions.add(binder)
+            }
+            return binder
+        }
+
         override fun lookupSFTPServer(): String {
             val termuxPrefix = File(UserResolver.TERMUX_PREFIX)
             for (name in arrayOf("libexec/sftp-server", "lib/openssh/sftp-server")) {
@@ -219,6 +246,28 @@ class RootServer : RootService() {
         return env.map { (k, v) -> "$k=$v" }.toTypedArray()
     }
 
+    private inner class BridgeSessionBinder(
+        private val session: BridgeSession,
+    ) : IBridgeSession.Stub() {
+
+        override fun getFileDescriptor(): ParcelFileDescriptor = ParcelFileDescriptor.fromFd(session.fileDescriptor())
+
+        override fun getName(): String = session.name()
+
+        override fun isInet6Active(): Boolean = session.inet6Active()
+
+        override fun setEgress(interfaceName: String?) {
+            session.setEgress(interfaceName ?: "")
+        }
+
+        override fun close() {
+            synchronized(bridgeSessions) {
+                bridgeSessions.remove(this)
+            }
+            session.close()
+        }
+    }
+
     private class RootShellSession(
         private val session: ShellSession,
     ) : IRootShellSession.Stub() {
@@ -363,6 +412,17 @@ class RootServer : RootService() {
     override fun onBind(intent: Intent): IBinder = binder
 
     override fun onDestroy() {
+        val sessions = synchronized(bridgeSessions) {
+            val copied = bridgeSessions.toList()
+            bridgeSessions.clear()
+            copied
+        }
+        for (session in sessions) {
+            try {
+                session.close()
+            } catch (_: Exception) {
+            }
+        }
         stopTetheringMonitor()
         neighborSubscription?.close()
         neighborSubscription = null