Move catch blocks to child classes

This reverts commit 07a48bc20b and f870093c94.

mobile/src/main/java/com/github/shadowsocks/bg/LocalSocketListener.kt

@@ -25,75 +25,46 @@ import android.net.LocalSocket
 import android.net.LocalSocketAddress
 import android.util.Log
 import com.github.shadowsocks.App.Companion.app
-import com.github.shadowsocks.JniHelper
 import java.io.File
 import java.io.IOException
 import java.util.concurrent.atomic.AtomicReference
 
-abstract class LocalSocketListener(private val tag: String) : Thread() {
+abstract class LocalSocketListener(protected val tag: String) : Thread() {
     init {
         setUncaughtExceptionHandler(app::track)
     }
 
     protected abstract val socketFile: File
-    private val localSocket = AtomicReference<LocalSocket?>()
+    private val serverSocket = AtomicReference<LocalServerSocket?>()
 
     /**
      * Inherited class do not need to close input/output streams as they will be closed automatically.
      */
     protected abstract fun accept(socket: LocalSocket)
     override fun run() {
-
-        JniHelper.unlink(socketFile.absolutePath)
-        Thread.sleep(1000) // trick to close the previous local socket safely
-
-        val serverSocket: LocalServerSocket? = try {
-            val ls = LocalSocket()
-            localSocket.set(ls)
-            ls.bind(LocalSocketAddress(socketFile.absolutePath, LocalSocketAddress.Namespace.FILESYSTEM))
-            LocalServerSocket(ls.fileDescriptor)
+        socketFile.delete()
+        try {
+            val localSocket = LocalSocket()
+            localSocket.bind(LocalSocketAddress(socketFile.absolutePath, LocalSocketAddress.Namespace.FILESYSTEM))
+            serverSocket.set(LocalServerSocket(localSocket.fileDescriptor))
         } catch (e: IOException) {
             Log.e(tag, "unable to bind", e)
-            null
+            return
         }
-
         while (true) {
+            val serverSocket = serverSocket.get() ?: return
             try {
-                val socket = serverSocket?.accept() ?: break
-
-                try {
-                    accept(socket)
-                } catch (e: Exception) {
-                    Log.e(tag, "Error when recv traffic stat", e)
-                    app.track(e)
-                }
-
-                try {
-                    socket.close()
-                } catch (e: IOException) {
-                    Log.e(tag, "Error when closing the local socket", e)
-                    app.track(e)
-                }
-
+                serverSocket.accept()
             } catch (e: IOException) {
                 Log.e(tag, "Error when accept socket", e)
                 app.track(e)
-                break
-            }
+                null
+            }?.use(this::accept)
         }
-
-        try {
-            serverSocket?.close()
-        } catch (e: IOException) {
-            Log.e(tag, "Error when closing socket", e)
-            app.track(e)
-        }
-
-        Log.d(tag, "thread exit")
     }
 
     fun stopThread() {
-        val old = localSocket.getAndSet(null) ?: return
+        val old = serverSocket.getAndSet(null) ?: return
         try {
             old.close()
         } catch (_: Exception) { }  // ignore

mobile/src/main/java/com/github/shadowsocks/bg/TrafficMonitorThread.kt

@@ -21,6 +21,7 @@
 package com.github.shadowsocks.bg
 
 import android.net.LocalSocket
+import android.util.Log
 import com.github.shadowsocks.App.Companion.app
 import java.io.File
 import java.io.IOException
@@ -31,10 +32,15 @@ class TrafficMonitorThread : LocalSocketListener("TrafficMonitorThread") {
     override val socketFile = File(app.filesDir, "/stat_path")
 
     override fun accept(socket: LocalSocket) {
-        val buffer = ByteArray(16)
-        if (socket.inputStream.read(buffer) != 16) throw IOException("Unexpected traffic stat length")
-        val stat = ByteBuffer.wrap(buffer).order(ByteOrder.LITTLE_ENDIAN)
-        TrafficMonitor.update(stat.getLong(0), stat.getLong(8))
-        socket.outputStream.write(0)
+        try {
+            val buffer = ByteArray(16)
+            if (socket.inputStream.read(buffer) != 16) throw IOException("Unexpected traffic stat length")
+            val stat = ByteBuffer.wrap(buffer).order(ByteOrder.LITTLE_ENDIAN)
+            TrafficMonitor.update(stat.getLong(0), stat.getLong(8))
+            socket.outputStream.write(0)
+        } catch (e: Exception) {
+            Log.e(tag, "Error when recv traffic stat", e)
+            app.track(e)
+        }
     }
 }

mobile/src/main/java/com/github/shadowsocks/bg/VpnService.kt

@@ -55,13 +55,18 @@ class VpnService : BaseVpnService(), LocalDnsService.Interface {
         override val socketFile: File = File(filesDir, "protect_path")
 
         override fun accept(socket: LocalSocket) {
-            socket.inputStream.read()
-            val fds = socket.ancillaryFileDescriptors
-            if (fds.isEmpty()) return
-            val fd = getInt.invoke(fds.first()) as Int
-            val ret = protect(fd)
-            JniHelper.close(fd) // Trick to close file decriptor
-            socket.outputStream.write(if (ret) 0 else 1)
+            try {
+                socket.inputStream.read()
+                val fds = socket.ancillaryFileDescriptors
+                if (fds.isEmpty()) return
+                val fd = getInt.invoke(fds.first()) as Int
+                val ret = protect(fd)
+                JniHelper.close(fd) // Trick to close file decriptor
+                socket.outputStream.write(if (ret) 0 else 1)
+            } catch (e: Exception) {
+                Log.e(tag, "Error when protect socket", e)
+                app.track(e)
+            }
         }
     }
     class NullConnectionException : NullPointerException()