jscanner

commit e66637a019cd2581fea9d5971c25ae7cf7ec6d56
parent a7777d6b52a31d2045801cadfe1a61c196d9f6bd
Author: Matthias Jaros <jaros@mailbox.org>
Date:   Mon, 16 Mar 2026 15:57:09 +0100

Replaced printStackTrace with proper message, handling interrupts now
and also moved workerthreads to target level instead of global level

Diffstat:
M
src/main/java/com/it_jaros/networkScanner/App.java
 | 
6
+++---
M
src/main/java/com/it_jaros/networkScanner/Scanner.java
 | 
28
+++++++++++++++++++---------

2 files changed, 22 insertions(+), 12 deletions(-)
diff --git a/src/main/java/com/it_jaros/networkScanner/App.java b/src/main/java/com/it_jaros/networkScanner/App.java
@@ -12,15 +12,15 @@ public class App {
                     options.delayInMillis());
             printResults(scanner.scan(options));
         } catch (IllegalArgumentException e) {
-            System.out.println(e.getMessage());
+            System.out.printf("Error while parsing arguments: %s", e.getMessage());
             cliParser.usageAndExit();
         } catch (Exception e) {
-            e.printStackTrace();
+            System.out.printf("ERROR %s", e.getMessage());
         }
     }
 
     public static void printResults(List<ScanResult> results) {
-        results.forEach(r -> printResult(r));
+        results.forEach(App::printResult);
     }
 
     private static void printResult(ScanResult result) {
diff --git a/src/main/java/com/it_jaros/networkScanner/Scanner.java b/src/main/java/com/it_jaros/networkScanner/Scanner.java
@@ -22,7 +22,6 @@ public class Scanner {
 
     private final Counter counter = new Counter();
     private final ProgressBar progressBar = new ProgressBar();
-    private final Semaphore maxWorkers = new Semaphore(1000);
     private final Semaphore socketLimit;
     private final int timeoutInMillis;
     private final long delayInNanos;
@@ -46,11 +45,13 @@ public class Scanner {
                 futures.add(executor.submit(() -> scanTarget(target, ports)));
             }
 
-            futures.forEach((f) -> {
+            futures.forEach((Future<ScanResult> f) -> {
                 try {
                     results.add(f.get());
-                } catch (InterruptedException | ExecutionException e) {
-                    e.printStackTrace();
+                } catch (InterruptedException e) {
+                    Thread.currentThread().interrupt();
+                } catch (ExecutionException e) {
+                    System.out.printf("%s -> %s%n", e.getClass().getSimpleName(), e.getMessage());
                 }
             });
         }
@@ -63,6 +64,7 @@ public class Scanner {
     private ScanResult scanTarget(String target, String ports) {
         PortRange portRange = new PortRange(ports);
         AtomicLong portSlotFactory = new AtomicLong(System.nanoTime());
+        Semaphore maxWorkers = new Semaphore(1000);
         BitSet openPorts = new BitSet(PortRange.MAX_PORT);
 
         Progress progress = new Progress(target, portRange.getTotal(), new AtomicInteger(), new AtomicInteger());
@@ -88,17 +90,24 @@ public class Scanner {
                 }));
             }
 
-            futures.forEach(f -> {
+            List<Throwable> errors = new ArrayList<>();
+            for (Future<Integer> f : futures) {
                 try {
                     int port = f.get();
                     if (port != -1) {
                         // openPorts is not threadsafe, so we do not update it outside the worker threads
                         openPorts.set(port);
                     }
-                } catch (InterruptedException | ExecutionException e) {
-                    e.printStackTrace();
+                } catch (InterruptedException e) {
+                    Thread.currentThread().interrupt();
+                } catch (ExecutionException e) {
+                    errors.add(e);
                 }
-            });
+            }
+
+            if (!errors.isEmpty()) {
+                System.out.printf("Errors happened during scan of target %s%nErrors:%s -> %s", target, errors.size(), errors);
+            }
         }
 
         return new ScanResult(target, openPorts);
@@ -128,8 +137,9 @@ public class Scanner {
             socket.connect(new InetSocketAddress(target, port), timeoutInMillis);
             return true;
         } catch (SocketException | SocketTimeoutException ignored) {
+            // Will happen a lot when scanning for open ports, so not needed
         } catch (IOException e) {
-            System.out.println(e.getClass().getSimpleName() + ": " + e.getMessage());
+            System.out.printf("%s -> %s", e.getClass().getSimpleName(), e.getMessage());
         } finally {
             counter.dec();
             socketLimit.release();