From 07beb6dd9dc377b644ad47a8392f2f9ca27241f4 Mon Sep 17 00:00:00 2001
From: Wei Jianfeng <676654309@qq.com>
Date: Wed, 28 Oct 2015 21:16:33 +0800
Subject: [PATCH] a methed for Android to set socket options

---
 src/org/jnasockopt/AndroidSocketUtil.java | 74 +++++++++++++++++++++++
 1 file changed, 74 insertions(+)
 create mode 100644 src/org/jnasockopt/AndroidSocketUtil.java

diff --git a/src/org/jnasockopt/AndroidSocketUtil.java b/src/org/jnasockopt/AndroidSocketUtil.java
new file mode 100644
index 0000000..cf89f20
--- /dev/null
+++ b/src/org/jnasockopt/AndroidSocketUtil.java
@@ -0,0 +1,74 @@
+import java.io.FileDescriptor;
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.net.Socket;
+import java.net.SocketException;
+
+public class AndroidSocketUtil {
+
+	/*
+	 * you can get the following constants from JNASockOptionDetailsLinux (for
+	 * android system)
+	 */
+	private final static int SOL_TCP = 6;
+	private final static int TCP_KEEPIDLE = 4;
+	private final static int TCP_KEEPINTVL = 5;
+	private final static int TCP_KEEPCNT = 6;
+
+	/**
+	 * The method uses java reflection to set socket options in Android system
+	 * and it's only available for Android 4.0 or later versions
+	 * 
+	 * @param socket
+	 *            the Socket object which you want to change its socket options
+	 * @param idleTimeout
+	 *            timeout value
+	 * @param interval
+	 *            interval time
+	 * @param count
+	 *            the time of reconnection
+	 */
+	protected static void setKeepaliveSocketOptions(Socket socket,
+			int idleTimeout, int interval, int count) {
+		try {
+			socket.setKeepAlive(true);
+			try {
+				Field socketImplField = Class.forName("java.net.Socket")
+						.getDeclaredField("impl");
+				socketImplField.setAccessible(true);
+				if (socketImplField != null) {
+					Object plainSocketImpl = socketImplField.get(socket);
+					Field fileDescriptorField = Class.forName(
+							"java.net.SocketImpl").getDeclaredField("fd");
+					if (fileDescriptorField != null) {
+						fileDescriptorField.setAccessible(true);
+						FileDescriptor fileDescriptor = (FileDescriptor) fileDescriptorField
+								.get(plainSocketImpl);
+						Class libCoreClass = Class
+								.forName("libcore.io.Libcore");
+						Field osField = libCoreClass.getDeclaredField("os");
+						osField.setAccessible(true);
+						Object libcoreOs = osField.get(libCoreClass);
+						Method setSocketOptsMethod = Class.forName(
+								"libcore.io.ForwardingOs").getDeclaredMethod(
+								"setsockoptInt", FileDescriptor.class,
+								int.class, int.class, int.class);
+						if (setSocketOptsMethod != null) {
+							setSocketOptsMethod.invoke(libcoreOs,
+									fileDescriptor, SOL_TCP, TCP_KEEPIDLE,
+									idleTimeout);
+							setSocketOptsMethod.invoke(libcoreOs,
+									fileDescriptor, SOL_TCP, TCP_KEEPINTVL,
+									interval);
+							setSocketOptsMethod
+									.invoke(libcoreOs, fileDescriptor, SOL_TCP,
+											TCP_KEEPCNT, count);
+						}
+					}
+				}
+			} catch (Exception reflectionException) {
+			}
+		} catch (SocketException e) {
+		}
+	}
+}