Feat: 데이터 포트 범위 지정 기능 추가

방화벽 환경에서 특정 포트 범위만 개방하여 사용할 수 있도록 데이터 포트 범위 설정 기능 추가.
- FTPConfig에 minDataPort, maxDataPort 설정 추가 (기본값: 50000-50100)
- FTPDataConnection에서 지정된 범위 내 사용 가능한 포트 자동 할당
- MainActivity UI에 데이터 포트 범위 설정 필드 추가
- 포트 범위 유효성 검증 (최소 10개 포트, 1024-65535 범위)
- 범위 미지정 시 기존처럼 랜덤 포트 사용

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

app/src/main/java/be/gyu/android/server/ftp/FTPConfig.java

@@ -9,8 +9,12 @@ public class FTPConfig {
     private static final String KEY_PORT = "ftp_port";
     private static final String KEY_ROOT_DIR_URI = "root_directory_uri";
     private static final String KEY_ROOT_DIR_PATH = "root_directory_path";
+    private static final String KEY_MIN_DATA_PORT = "min_data_port";
+    private static final String KEY_MAX_DATA_PORT = "max_data_port";
 
     private static final int DEFAULT_PORT = 2121;
+    private static final int DEFAULT_MIN_DATA_PORT = 50000;
+    private static final int DEFAULT_MAX_DATA_PORT = 50100;
 
     private final SharedPreferences preferences;
 
@@ -60,4 +64,27 @@ public class FTPConfig {
                 .putString(KEY_ROOT_DIR_PATH, rootDirPath)
                 .apply();
     }
+
+    public int getMinDataPort() {
+        return preferences.getInt(KEY_MIN_DATA_PORT, DEFAULT_MIN_DATA_PORT);
+    }
+
+    public void setMinDataPort(int port) {
+        preferences.edit().putInt(KEY_MIN_DATA_PORT, port).apply();
+    }
+
+    public int getMaxDataPort() {
+        return preferences.getInt(KEY_MAX_DATA_PORT, DEFAULT_MAX_DATA_PORT);
+    }
+
+    public void setMaxDataPort(int port) {
+        preferences.edit().putInt(KEY_MAX_DATA_PORT, port).apply();
+    }
+
+    public void setDataPortRange(int minPort, int maxPort) {
+        preferences.edit()
+                .putInt(KEY_MIN_DATA_PORT, minPort)
+                .putInt(KEY_MAX_DATA_PORT, maxPort)
+                .apply();
+    }
 }

app/src/main/java/be/gyu/android/server/ftp/FTPDataConnection.java

@@ -20,14 +20,41 @@ public class FTPDataConnection {
     private int passivePort;
 
     public boolean openPassiveMode(InetAddress bindAddress) {
-        try {
-            // Use port 0 to get a random available port
-            passiveSocket = new ServerSocket(0, 1, bindAddress);
-            passiveSocket.setSoTimeout(DATA_CONNECTION_TIMEOUT);
-            passivePort = passiveSocket.getLocalPort();
+        return openPassiveMode(bindAddress, 0, 0);
+    }
 
-            Log.i(TAG, "Passive mode enabled on port: " + passivePort);
-            return true;
+    public boolean openPassiveMode(InetAddress bindAddress, int minPort, int maxPort) {
+        try {
+            if (minPort <= 0 || maxPort <= 0 || minPort > maxPort) {
+                // Use port 0 to get a random available port
+                passiveSocket = new ServerSocket(0, 1, bindAddress);
+                passiveSocket.setSoTimeout(DATA_CONNECTION_TIMEOUT);
+                passivePort = passiveSocket.getLocalPort();
+                Log.i(TAG, "Passive mode enabled on random port: " + passivePort);
+                return true;
+            }
+
+            // Try to find an available port in the specified range
+            IOException lastException = null;
+            for (int port = minPort; port <= maxPort; port++) {
+                try {
+                    passiveSocket = new ServerSocket(port, 1, bindAddress);
+                    passiveSocket.setSoTimeout(DATA_CONNECTION_TIMEOUT);
+                    passivePort = passiveSocket.getLocalPort();
+                    Log.i(TAG, "Passive mode enabled on port: " + passivePort + " (range: " + minPort + "-" + maxPort + ")");
+                    return true;
+                } catch (IOException e) {
+                    lastException = e;
+                    // Port is in use, try next port
+                }
+            }
+
+            // No available port found in range
+            Log.e(TAG, "No available port in range " + minPort + "-" + maxPort);
+            if (lastException != null) {
+                Log.e(TAG, "Last error: " + lastException.getMessage());
+            }
+            return false;
         } catch (IOException e) {
             Log.e(TAG, "Error opening passive mode: " + e.getMessage());
             return false;

app/src/main/java/be/gyu/android/server/ftp/FTPServer.java

@@ -23,19 +23,27 @@ public class FTPServer {
     private int port;
     private Context context;
     private Uri rootDirectoryUri;
+    private int minDataPort = 0;
+    private int maxDataPort = 0;
 
     public FTPServer(Context context) {
-        this(context, DEFAULT_PORT, null);
+        this(context, DEFAULT_PORT, null, 0, 0);
     }
 
     public FTPServer(Context context, int port) {
-        this(context, port, null);
+        this(context, port, null, 0, 0);
     }
 
     public FTPServer(Context context, int port, Uri rootDirectoryUri) {
+        this(context, port, rootDirectoryUri, 0, 0);
+    }
+
+    public FTPServer(Context context, int port, Uri rootDirectoryUri, int minDataPort, int maxDataPort) {
         this.context = context;
         this.port = port;
         this.rootDirectoryUri = rootDirectoryUri;
+        this.minDataPort = minDataPort;
+        this.maxDataPort = maxDataPort;
         this.executorService = Executors.newFixedThreadPool(MAX_CONNECTIONS);
     }
 
@@ -56,7 +64,7 @@ public class FTPServer {
                         Socket clientSocket = serverSocket.accept();
                         Log.i(TAG, "New client connection from: " + clientSocket.getInetAddress());
 
-                        FTPSession session = new FTPSession(clientSocket, context, rootDirectoryUri);
+                        FTPSession session = new FTPSession(clientSocket, context, rootDirectoryUri, minDataPort, maxDataPort);
                         executorService.execute(session);
 
                     } catch (IOException e) {

app/src/main/java/be/gyu/android/server/ftp/FTPService.java

@@ -37,11 +37,13 @@ public class FTPService extends Service {
             if (ACTION_START.equals(action)) {
                 int port = intent.getIntExtra("port", 2121);
                 String rootDirUriString = intent.getStringExtra("rootDirUri");
+                int minDataPort = intent.getIntExtra("minDataPort", 0);
+                int maxDataPort = intent.getIntExtra("maxDataPort", 0);
                 android.net.Uri rootDirUri = null;
                 if (rootDirUriString != null && !rootDirUriString.isEmpty()) {
                     rootDirUri = android.net.Uri.parse(rootDirUriString);
                 }
-                startFTPServer(port, rootDirUri);
+                startFTPServer(port, rootDirUri, minDataPort, maxDataPort);
             } else if (ACTION_STOP.equals(action)) {
                 stopFTPServer();
             }
@@ -50,19 +52,24 @@ public class FTPService extends Service {
         return START_STICKY;
     }
 
-    private void startFTPServer(int port, android.net.Uri rootDirUri) {
+    private void startFTPServer(int port, android.net.Uri rootDirUri, int minDataPort, int maxDataPort) {
         if (ftpServer != null && ftpServer.isRunning()) {
             Log.w(TAG, "FTP Server is already running");
             return;
         }
 
-        ftpServer = new FTPServer(this, port, rootDirUri);
+        ftpServer = new FTPServer(this, port, rootDirUri, minDataPort, maxDataPort);
         ftpServer.start();
 
-        Notification notification = createNotification("FTP Server is running on port " + ftpServer.getPort());
+        String notificationText = "FTP Server is running on port " + ftpServer.getPort();
+        if (minDataPort > 0 && maxDataPort > 0) {
+            notificationText += " (Data ports: " + minDataPort + "-" + maxDataPort + ")";
+        }
+        Notification notification = createNotification(notificationText);
         startForeground(NOTIFICATION_ID, notification);
 
-        Log.i(TAG, "FTP Server started on port " + port + " with root URI: " + rootDirUri);
+        Log.i(TAG, "FTP Server started on port " + port + " with root URI: " + rootDirUri +
+                ", data port range: " + minDataPort + "-" + maxDataPort);
     }
 
     private void stopFTPServer() {

app/src/main/java/be/gyu/android/server/ftp/FTPSession.java

@@ -31,15 +31,23 @@ public class FTPSession implements Runnable {
     private FTPDataConnection dataConnection;
     private String transferType = "A"; // A = ASCII, I = Binary
     private boolean useUtf8 = true; // UTF-8 enabled by default for better compatibility
+    private int minDataPort = 0;
+    private int maxDataPort = 0;
 
     public FTPSession(Socket socket, Context context) {
-        this(socket, context, null);
+        this(socket, context, null, 0, 0);
     }
 
     public FTPSession(Socket socket, Context context, Uri rootDirectoryUri) {
+        this(socket, context, rootDirectoryUri, 0, 0);
+    }
+
+    public FTPSession(Socket socket, Context context, Uri rootDirectoryUri, int minDataPort, int maxDataPort) {
         this.controlSocket = socket;
         this.fileSystem = new FTPFileSystem(context, rootDirectoryUri);
         this.dataConnection = null;
+        this.minDataPort = minDataPort;
+        this.maxDataPort = maxDataPort;
     }
 
     @Override
@@ -405,7 +413,7 @@ public class FTPSession implements Runnable {
         // Get server address from control socket
         String serverAddress = controlSocket.getLocalAddress().getHostAddress();
 
-        if (dataConnection.openPassiveMode(controlSocket.getLocalAddress())) {
+        if (dataConnection.openPassiveMode(controlSocket.getLocalAddress(), minDataPort, maxDataPort)) {
             int port = dataConnection.getPassivePort();
 
             // Format: h1,h2,h3,h4,p1,p2

app/src/main/java/be/gyu/android/server/ftp/MainActivity.java

@@ -8,6 +8,8 @@ import androidx.core.content.ContextCompat;
 import androidx.documentfile.provider.DocumentFile;
 
 import android.Manifest;
+import android.app.ActivityManager;
+import android.content.Context;
 import android.content.Intent;
 import android.content.pm.PackageManager;
 import android.net.Uri;
@@ -33,6 +35,8 @@ public class MainActivity extends AppCompatActivity {
     private TextView rootDirPathTextView;
     private Button selectDirButton;
     private Button saveSettingsButton;
+    private EditText minDataPortEditText;
+    private EditText maxDataPortEditText;
 
     private FTPConfig config;
     private ActivityResultLauncher<Uri> directoryPickerLauncher;
@@ -89,11 +93,15 @@ public class MainActivity extends AppCompatActivity {
         rootDirPathTextView = findViewById(R.id.rootDirPathTextView);
         selectDirButton = findViewById(R.id.selectDirButton);
         saveSettingsButton = findViewById(R.id.saveSettingsButton);
+        minDataPortEditText = findViewById(R.id.minDataPortEditText);
+        maxDataPortEditText = findViewById(R.id.maxDataPortEditText);
     }
 
     private void loadSettings() {
         int port = config.getPort();
         String rootPath = config.getRootDirectoryPath();
+        int minDataPort = config.getMinDataPort();
+        int maxDataPort = config.getMaxDataPort();
 
         portEditText.setText(String.valueOf(port));
         portTextView.setText("Port: " + port);
@@ -103,6 +111,9 @@ public class MainActivity extends AppCompatActivity {
         } else {
             rootDirPathTextView.setText("Not selected");
         }
+
+        minDataPortEditText.setText(String.valueOf(minDataPort));
+        maxDataPortEditText.setText(String.valueOf(maxDataPort));
     }
 
     private void setupListeners() {
@@ -140,7 +151,45 @@ public class MainActivity extends AppCompatActivity {
             return;
         }
 
+        // Validate data port range
+        String minPortStr = minDataPortEditText.getText().toString().trim();
+        String maxPortStr = maxDataPortEditText.getText().toString().trim();
+
+        int minDataPort = 0;
+        int maxDataPort = 0;
+
+        if (!minPortStr.isEmpty() || !maxPortStr.isEmpty()) {
+            if (minPortStr.isEmpty() || maxPortStr.isEmpty()) {
+                Toast.makeText(this, "Please enter both min and max data ports or leave both empty", Toast.LENGTH_SHORT).show();
+                return;
+            }
+
+            try {
+                minDataPort = Integer.parseInt(minPortStr);
+                maxDataPort = Integer.parseInt(maxPortStr);
+
+                if (minDataPort < 1024 || minDataPort > 65535 || maxDataPort < 1024 || maxDataPort > 65535) {
+                    Toast.makeText(this, "Data ports must be between 1024 and 65535", Toast.LENGTH_SHORT).show();
+                    return;
+                }
+
+                if (minDataPort >= maxDataPort) {
+                    Toast.makeText(this, "Min data port must be less than max data port", Toast.LENGTH_SHORT).show();
+                    return;
+                }
+
+                if (maxDataPort - minDataPort < 10) {
+                    Toast.makeText(this, "Data port range should be at least 10 ports", Toast.LENGTH_SHORT).show();
+                    return;
+                }
+            } catch (NumberFormatException e) {
+                Toast.makeText(this, "Invalid data port number", Toast.LENGTH_SHORT).show();
+                return;
+            }
+        }
+
         config.setPort(port);
+        config.setDataPortRange(minDataPort, maxDataPort);
         portTextView.setText("Port: " + port);
 
         Toast.makeText(this, "Settings saved", Toast.LENGTH_SHORT).show();
@@ -194,6 +243,8 @@ public class MainActivity extends AppCompatActivity {
         serviceIntent.setAction(FTPService.ACTION_START);
         serviceIntent.putExtra("port", config.getPort());
         serviceIntent.putExtra("rootDirUri", rootDirUri);
+        serviceIntent.putExtra("minDataPort", config.getMinDataPort());
+        serviceIntent.putExtra("maxDataPort", config.getMaxDataPort());
 
         if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
             startForegroundService(serviceIntent);
@@ -239,4 +290,27 @@ public class MainActivity extends AppCompatActivity {
             }
         }
     }
+
+    /**
+     * Check if FTPService is currently running in the background
+     */
+    private boolean isServiceRunning() {
+        ActivityManager manager = (ActivityManager) getSystemService(Context.ACTIVITY_SERVICE);
+        if (manager != null) {
+            for (ActivityManager.RunningServiceInfo service : manager.getRunningServices(Integer.MAX_VALUE)) {
+                if (FTPService.class.getName().equals(service.service.getClassName())) {
+                    return true;
+                }
+            }
+        }
+        return false;
+    }
+
+    @Override
+    protected void onResume() {
+        super.onResume();
+        // Sync UI with actual service state when activity resumes
+        isServerRunning = isServiceRunning();
+        updateUI();
+    }
 }

app/src/main/res/layout/activity_main.xml

@@ -144,6 +144,62 @@
         app:layout_constraintTop_toBottomOf="@id/rootDirPathTextView"
         app:layout_constraintStart_toStartOf="parent" />
 
+    <TextView
+        android:id="@+id/dataPortRangeLabel"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="Data Port Range:"
+        android:textSize="16sp"
+        android:layout_marginTop="16dp"
+        app:layout_constraintTop_toBottomOf="@id/selectDirButton"
+        app:layout_constraintStart_toStartOf="parent" />
+
+    <TextView
+        android:id="@+id/minDataPortLabel"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="Min:"
+        android:textSize="14sp"
+        android:layout_marginTop="8dp"
+        app:layout_constraintTop_toBottomOf="@id/dataPortRangeLabel"
+        app:layout_constraintStart_toStartOf="parent" />
+
+    <EditText
+        android:id="@+id/minDataPortEditText"
+        android:layout_width="0dp"
+        android:layout_height="wrap_content"
+        android:inputType="number"
+        android:hint="50000"
+        android:layout_marginStart="16dp"
+        app:layout_constraintBaseline_toBaselineOf="@id/minDataPortLabel"
+        app:layout_constraintStart_toEndOf="@id/minDataPortLabel"
+        app:layout_constraintEnd_toStartOf="@id/maxDataPortLabel"
+        app:layout_constraintWidth_default="percent"
+        app:layout_constraintHorizontal_weight="1" />
+
+    <TextView
+        android:id="@+id/maxDataPortLabel"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="Max:"
+        android:textSize="14sp"
+        android:layout_marginStart="16dp"
+        app:layout_constraintBaseline_toBaselineOf="@id/minDataPortLabel"
+        app:layout_constraintStart_toEndOf="@id/minDataPortEditText" />
+
+    <EditText
+        android:id="@+id/maxDataPortEditText"
+        android:layout_width="0dp"
+        android:layout_height="wrap_content"
+        android:inputType="number"
+        android:hint="50100"
+        android:layout_marginStart="16dp"
+        app:layout_constraintBaseline_toBaselineOf="@id/minDataPortLabel"
+        app:layout_constraintStart_toEndOf="@id/maxDataPortLabel"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintWidth_default="percent"
+        app:layout_constraintHorizontal_weight="1" />
+
     <Button
         android:id="@+id/saveSettingsButton"
         android:layout_width="wrap_content"
@@ -151,7 +207,7 @@
         android:text="Save Settings"
         android:minWidth="150dp"
         android:layout_marginTop="24dp"
-        app:layout_constraintTop_toBottomOf="@id/selectDirButton"
+        app:layout_constraintTop_toBottomOf="@id/minDataPortLabel"
         app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintEnd_toEndOf="parent" />