From 192160541bb31c74468509faf5b19f42b0e4d450 Mon Sep 17 00:00:00 2001
From: Matthias Jaros <jarlucmat@mailbox.org>
Date: Mon, 6 Jul 2026 15:42:44 +0200
Subject: Reworked exception handling. Collect now only weird exceptions and
 print them before results to stderr

---
 src/main/java/com/it_jaros/jscanner/Scanner.java | 25 +++++++++++++-----------
 1 file changed, 14 insertions(+), 11 deletions(-)

(limited to 'src/main/java/com/it_jaros/jscanner/Scanner.java')

diff --git a/src/main/java/com/it_jaros/jscanner/Scanner.java b/src/main/java/com/it_jaros/jscanner/Scanner.java
index 55b42fc..63b1d14 100644
--- a/src/main/java/com/it_jaros/jscanner/Scanner.java
+++ b/src/main/java/com/it_jaros/jscanner/Scanner.java
@@ -107,7 +107,7 @@ public class Scanner implements AutoCloseable {
             } catch (InterruptedException e) {
                 Thread.currentThread().interrupt();
             } catch (ExecutionException e) {
-                System.out.printf("%s -> %s%n", e.getClass().getSimpleName(), e.getMessage());
+                System.err.printf("%s -> %s%n", e.getClass().getSimpleName(), e.getMessage());
             }
         }
 
@@ -129,10 +129,10 @@ public class Scanner implements AutoCloseable {
 
         if (!disableOnlineCheck && !checkHostOnline(host)) {
             // Unreachable host
-            return new ScanResult(host, openPorts, filteredPorts, serviceTypes);
+            return new ScanResult(host, openPorts, filteredPorts, serviceTypes, List.of());
         }
 
-        List<Throwable> errors = new ArrayList<>();
+        List<ScanFailure> scanFailures = new ArrayList<>();
         final AtomicLong portSlotFactory = new AtomicLong(System.nanoTime());
         // producer thread
         ProducerState<PortResult> state = startProducer(
@@ -173,6 +173,13 @@ public class Scanner implements AutoCloseable {
                             // sonarcube glücklich machen
                         }
                     }
+                    Exception e = portResult.getException();
+                    if (e != null) {
+                        scanFailures.add(new ScanFailure(portResult.getPort(), ExceptionInfo.from(e)));
+                    }
+                } catch (ExecutionException e) {
+                    // something more serious did not work
+                    System.err.printf("%s -> %s%n", e.getClass().getSimpleName(), e.getMessage());
                 } finally {
                     scan.getThreadCounter().dec();
                     state.activeWorkers().release();
@@ -180,16 +187,10 @@ public class Scanner implements AutoCloseable {
                 }
             } catch (InterruptedException ignored) {
                 Thread.currentThread().interrupt();
-            } catch (ExecutionException e) {
-                errors.add(e);
             }
         }
 
-        if (!errors.isEmpty()) {
-            System.out.printf("Errors happened during scan of host %s%nErrors:%s -> %s", host, errors.size(), errors);
-        }
-
-        return new ScanResult(host, openPorts, filteredPorts, serviceTypes);
+        return new ScanResult(host, openPorts, filteredPorts, serviceTypes, scanFailures);
     }
 
     /**
@@ -295,9 +296,11 @@ public class Scanner implements AutoCloseable {
             result.setState(PortState.FILTERED);
         } catch (ConnectException ignored) {
             result.setState(PortState.CLOSED);
-        } catch (IOException ignored) {
+        } 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);
         } finally {
             scan.getSocketCounter().dec();
             socketLimit.release();
-- 
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