support listen random port. #524

common/src/main/java/com/taobao/arthas/common/SocketUtils.java

@@ -3,10 +3,10 @@ package com.taobao.arthas.common;
 import java.net.InetAddress;
 import java.net.ServerSocket;
 import java.util.List;
+import java.util.Random;
 
 import javax.net.ServerSocketFactory;
 
-
 /**
  *
  * @author hengyunabc 2018-11-07
@@ -14,6 +14,20 @@ import javax.net.ServerSocketFactory;
  */
 public class SocketUtils {
 
+    /**
+     * The default minimum value for port ranges used when finding an available
+     * socket port.
+     */
+    public static final int PORT_RANGE_MIN = 1024;
+
+    /**
+     * The default maximum value for port ranges used when finding an available
+     * socket port.
+     */
+    public static final int PORT_RANGE_MAX = 65535;
+
+    private static final Random random = new Random(System.currentTimeMillis());
+
     private SocketUtils() {
     }
 
@@ -51,7 +65,7 @@ public class SocketUtils {
     public static boolean isTcpPortAvailable(int port) {
         try {
             ServerSocket serverSocket = ServerSocketFactory.getDefault().createServerSocket(port, 1,
-                            InetAddress.getByName("localhost"));
+                    InetAddress.getByName("localhost"));
             serverSocket.close();
             return true;
         } catch (Exception ex) {
@@ -59,4 +73,79 @@ public class SocketUtils {
         }
     }
 
+    /**
+     * Find an available TCP port randomly selected from the range
+     * [{@value #PORT_RANGE_MIN}, {@value #PORT_RANGE_MAX}].
+     * 
+     * @return an available TCP port number
+     * @throws IllegalStateException if no available port could be found
+     */
+    public static int findAvailableTcpPort() {
+        return findAvailableTcpPort(PORT_RANGE_MIN);
+    }
+
+    /**
+     * Find an available TCP port randomly selected from the range [{@code minPort},
+     * {@value #PORT_RANGE_MAX}].
+     * 
+     * @param minPort the minimum port number
+     * @return an available TCP port number
+     * @throws IllegalStateException if no available port could be found
+     */
+    public static int findAvailableTcpPort(int minPort) {
+        return findAvailableTcpPort(minPort, PORT_RANGE_MAX);
+    }
+
+    /**
+     * Find an available TCP port randomly selected from the range [{@code minPort},
+     * {@code maxPort}].
+     * 
+     * @param minPort the minimum port number
+     * @param maxPort the maximum port number
+     * @return an available TCP port number
+     * @throws IllegalStateException if no available port could be found
+     */
+    public static int findAvailableTcpPort(int minPort, int maxPort) {
+        return findAvailablePort(minPort, maxPort);
+    }
+
+    /**
+     * Find an available port for this {@code SocketType}, randomly selected from
+     * the range [{@code minPort}, {@code maxPort}].
+     * 
+     * @param minPort the minimum port number
+     * @param maxPort the maximum port number
+     * @return an available port number for this socket type
+     * @throws IllegalStateException if no available port could be found
+     */
+    private static int findAvailablePort(int minPort, int maxPort) {
+
+        int portRange = maxPort - minPort;
+        int candidatePort;
+        int searchCounter = 0;
+        do {
+            if (searchCounter > portRange) {
+                throw new IllegalStateException(
+                        String.format("Could not find an available tcp port in the range [%d, %d] after %d attempts",
+                                minPort, maxPort, searchCounter));
+            }
+            candidatePort = findRandomPort(minPort, maxPort);
+            searchCounter++;
+        } while (!isTcpPortAvailable(candidatePort));
+
+        return candidatePort;
+    }
+
+    /**
+     * Find a pseudo-random port number within the range [{@code minPort},
+     * {@code maxPort}].
+     * 
+     * @param minPort the minimum port number
+     * @param maxPort the maximum port number
+     * @return a random port number within the specified range
+     */
+    private static int findRandomPort(int minPort, int maxPort) {
+        int portRange = maxPort - minPort;
+        return minPort + random.nextInt(portRange + 1);
+    }
 }

core/src/main/java/com/taobao/arthas/core/server/ArthasBootstrap.java

@@ -27,6 +27,7 @@ import com.alibaba.arthas.deps.org.slf4j.LoggerFactory;
 import com.alibaba.arthas.tunnel.client.TunnelClient;
 import com.taobao.arthas.common.AnsiLog;
 import com.taobao.arthas.common.PidUtils;
+import com.taobao.arthas.common.SocketUtils;
 import com.taobao.arthas.core.advisor.TransformerManager;
 import com.taobao.arthas.core.command.BuiltinCommandPack;
 import com.taobao.arthas.core.command.view.ResultViewResolver;
@@ -274,6 +275,18 @@ public class ArthasBootstrap {
             throw new IllegalStateException("already bind");
         }
 
+        // init random port
+        if (configure.getTelnetPort() == 0) {
+            int newTelnetPort = SocketUtils.findAvailableTcpPort();
+            configure.setTelnetPort(newTelnetPort);
+            logger().info("generate random telnet port: " + newTelnetPort);
+        }
+        if (configure.getHttpPort() == 0) {
+            int newHttpPort = SocketUtils.findAvailableTcpPort();
+            configure.setHttpPort(newHttpPort);
+            logger().info("generate random http port: " + newHttpPort);
+        }
+
         String agentId = null;
         try {
             if (configure.getTunnelServer() != null && configure.getHttpPort() > 0) {