Enable flipper android to use different ports based on prop

Summary:
Part 1 of enabling flipper to run on custom ports: android SDK.
Still to go: iOS SDK and desktop

This should allow you to run mobile apps that use flipper on different ports than the default (8089,8088).

`adb shell`
`su`
`setprop flipper.ports 1111,2222`

From what I can tell, this only works on rooted devices.

Reviewed By: passy

Differential Revision: D13753238

fbshipit-source-id: c5f370c9d8c7382e8c17fb81d4010c642ef7c114

android/src/main/java/com/facebook/flipper/android/AndroidFlipperClient.java

@@ -1,9 +1,8 @@
-/*
- *  Copyright (c) 2018-present, Facebook, Inc.
- *
- *  This source code is licensed under the MIT license found in the LICENSE
- *  file in the root directory of this source tree.
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
  *
+ * This source code is licensed under the MIT license found in the LICENSE
+ * file in the root directory of this source tree.
  */
 package com.facebook.flipper.android;
 
@@ -36,6 +35,8 @@ public final class AndroidFlipperClient {
       FlipperClientImpl.init(
           sFlipperThread.getEventBase(),
           sConnectionThread.getEventBase(),
+          FlipperProps.getInsecurePort(),
+          FlipperProps.getSecurePort(),
           getServerHost(app),
           "Android",
           getFriendlyDeviceName(),

android/src/main/java/com/facebook/flipper/android/FlipperClientImpl.java

@@ -1,9 +1,8 @@
-/*
- *  Copyright (c) Facebook, Inc.
- *
- *  This source code is licensed under the MIT license found in the LICENSE
- *  file in the root directory of this source tree.
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
  *
+ * <p>This source code is licensed under the MIT license found in the LICENSE file in the root
+ * directory of this source tree.
  */
 package com.facebook.flipper.android;
 
@@ -36,6 +35,8 @@ class FlipperClientImpl implements FlipperClient {
   public static native void init(
       EventBase callbackWorker,
       EventBase connectionWorker,
+      int insecurePort,
+      int securePort,
       String host,
       String os,
       String device,

android/src/main/java/com/facebook/flipper/android/FlipperProps.java

@@ -0,0 +1,84 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the LICENSE
+ * file in the root directory of this source tree.
+ */
+package com.facebook.flipper.android;
+
+import android.util.Log;
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.nio.charset.Charset;
+
+class FlipperProps {
+
+  private static final String FLIPPER_PORTS_PROP_NAME = "flipper.ports";
+  private static final int DEFAULT_INSECURE_PORT = 8089;
+  private static final int DEFAULT_SECURE_PORT = 8088;
+  private static final String TAG = "Flipper";
+
+  static int getInsecurePort() {
+    String propValue = getFlipperPortsPropValue();
+    return extractIntFromPropValue(propValue, 0, DEFAULT_INSECURE_PORT);
+  }
+
+  static int getSecurePort() {
+    String propValue = getFlipperPortsPropValue();
+    return extractIntFromPropValue(propValue, 1, DEFAULT_SECURE_PORT);
+  }
+
+  static int extractIntFromPropValue(String propValue, int index, int fallback) {
+    if (propValue != null && !propValue.isEmpty()) {
+      try {
+        String[] values = propValue.split(",");
+        if (values.length > index) {
+          return Integer.parseInt(values[index]);
+        }
+      } catch (NumberFormatException e) {
+        Log.e(TAG, "Failed to parse flipper.ports value: " + propValue);
+      }
+    }
+    return fallback;
+  }
+
+  private static String flipperPortsPropValue = null;
+
+  private static synchronized String getFlipperPortsPropValue() {
+    if (flipperPortsPropValue != null) {
+      return flipperPortsPropValue;
+    }
+    Process process = null;
+    BufferedReader reader = null;
+    try {
+      process =
+          Runtime.getRuntime().exec(new String[] {"/system/bin/getprop", FLIPPER_PORTS_PROP_NAME});
+      reader =
+          new BufferedReader(
+              new InputStreamReader(process.getInputStream(), Charset.forName("UTF-8")));
+
+      String lastLine = "";
+      String line;
+      while ((line = reader.readLine()) != null) {
+        lastLine = line;
+      }
+      flipperPortsPropValue = lastLine;
+    } catch (IOException e) {
+      Log.e(TAG, "Failed to query for flipper.ports prop", e);
+      flipperPortsPropValue = "";
+    } finally {
+      try {
+        if (reader != null) {
+          reader.close();
+        }
+      } catch (IOException e) {
+        Log.e(TAG, "Failed to close BufferedReader when reading flipper.ports prop", e);
+      }
+      if (process != null) {
+        process.destroy();
+      }
+    }
+    return flipperPortsPropValue;
+  }
+}