From 27cb977a8f7ae27388302b4f3343bdfc2cbb9838 Mon Sep 17 00:00:00 2001
From: Matthias Jaros <jarlucmat@mailbox.org>
Date: Thu, 13 Aug 2026 16:22:51 +0200
Subject: Increased speed 1000x times by replacing host reachable method with
 another port scan task. The speed is gained by removing thread pinning method
 isReachable()

---
 .../com/it_jaros/jns/scan/engine/ScanHostTask.java | 24 +++++++++-------------
 .../com/it_jaros/jns/scan/engine/ScanPortTask.java |  4 ----
 2 files changed, 10 insertions(+), 18 deletions(-)

diff --git a/src/main/java/com/it_jaros/jns/scan/engine/ScanHostTask.java b/src/main/java/com/it_jaros/jns/scan/engine/ScanHostTask.java
index 0fbfef0..ce06287 100644
--- a/src/main/java/com/it_jaros/jns/scan/engine/ScanHostTask.java
+++ b/src/main/java/com/it_jaros/jns/scan/engine/ScanHostTask.java
@@ -3,15 +3,13 @@ package com.it_jaros.jns.scan.engine;
 import com.it_jaros.jns.scan.Scan;
 import com.it_jaros.jns.scan.domain.PortRange;
 import com.it_jaros.jns.scan.domain.PortResult;
+import com.it_jaros.jns.scan.domain.PortState;
 import com.it_jaros.jns.scan.domain.ScanResult;
 
-import java.io.IOException;
-import java.net.InetAddress;
 import java.util.concurrent.Callable;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
-import java.util.concurrent.locks.LockSupport;
 
 public class ScanHostTask implements Callable<ScanResult> {
 
@@ -21,18 +19,16 @@ public class ScanHostTask implements Callable<ScanResult> {
     private final CancelledToken cancelledToken;
     private final boolean disableOnlineCheck;
     private final int maxWorkersPerHost;
-    private final int timeoutInMillis;
-    private final long delayInNanos;
+    private final PortResultAccumulator accumulator;
 
     public ScanHostTask(Scan scan, String host, ScanExecutionContext context) {
         this.scan = scan;
         this.host = host;
         this.context = context;
+        this.accumulator = new PortResultAccumulator(host);
         this.cancelledToken = context.cancelledToken();
-        this.delayInNanos = TimeUnit.MILLISECONDS.toNanos(Math.max(0, context.scanOptions().delayInMillis()));
         this.disableOnlineCheck = context.scanOptions().disableOnlineCheck();
         this.maxWorkersPerHost = context.scanOptions().maxWorkersPerHost();
-        this.timeoutInMillis = context.scanOptions().timeoutInMillis();
     }
 
     @Override
@@ -55,10 +51,6 @@ public class ScanHostTask implements Callable<ScanResult> {
                 // Unreachable host
                 return ScanResult.empty(host);
             }
-            // online check also sends packets to the target system.
-            // in order not to violate set delay time
-            // we wait here too
-            LockSupport.parkNanos(delayInNanos);
         }
 
         final PortRange portRange = new PortRange(scan.getPorts());
@@ -74,7 +66,6 @@ public class ScanHostTask implements Callable<ScanResult> {
         // we run as long as the producer is running OR
         // as long as things are in pipeline waiting to be processed
         // ONLY exception is when cancelled is set
-        final PortResultAccumulator accumulator = new PortResultAccumulator(host);
         while (!cancelledToken.isCancelled() && (state.running().get() || state.inPipeline().get() > 0)) {
             try {
                 PollState<PortResult> poll = getPortResult(state);
@@ -94,8 +85,13 @@ public class ScanHostTask implements Callable<ScanResult> {
 
     private boolean checkHostOnline() {
         try {
-            return InetAddress.getByName(host).isReachable(timeoutInMillis);
-        } catch (IOException e) {
+            PortResult result = new ScanPortTask(host, 7, context).call();
+            Exception exception = result.getException();
+            accumulator.add(result);
+            if (exception == null && !result.getState().equals(PortState.FILTERED)) {
+                return true;
+            }
+        } catch (Exception e) {
             // we ignore this error because it means that the host is probably not online
         }
 
diff --git a/src/main/java/com/it_jaros/jns/scan/engine/ScanPortTask.java b/src/main/java/com/it_jaros/jns/scan/engine/ScanPortTask.java
index c5591e7..b6c5964 100644
--- a/src/main/java/com/it_jaros/jns/scan/engine/ScanPortTask.java
+++ b/src/main/java/com/it_jaros/jns/scan/engine/ScanPortTask.java
@@ -8,7 +8,6 @@ import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.net.ConnectException;
 import java.net.InetSocketAddress;
-import java.net.NoRouteToHostException;
 import java.nio.ByteBuffer;
 import java.nio.channels.SocketChannel;
 import java.util.concurrent.Callable;
@@ -89,9 +88,6 @@ public class ScanPortTask implements Callable<PortResult> {
             }
         } catch (ConnectException ignored) {
             result.setState(PortState.CLOSED);
-        } catch (NoRouteToHostException ignored) {
-            // NoRouteToHostException: this can be safely ignored because the port is closed if a host is unreachable
-            // Will happen a lot when scanning for open ports, so not needed
         } catch (IOException e) {
             result.setException(e);
         }
-- 
cgit v1.3.1