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package com.it_jaros.network_scanner;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.net.SocketException;
import java.net.SocketTimeoutException;
import java.util.ArrayList;
import java.util.BitSet;
import java.util.List;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.concurrent.Semaphore;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.locks.LockSupport;
public class Scanner {
private final Counter counter = new Counter();
private final ProgressBar progressBar = new ProgressBar();
private final Semaphore socketLimit;
private final int timeoutInMillis;
private final long delayInNanos;
private final int maxWorkersPerHost;
public Scanner(int socketLimit, int timeoutInMillis, int delayInMillis, int maxWorkersPerHost) {
this.timeoutInMillis = timeoutInMillis;
this.delayInNanos = TimeUnit.MILLISECONDS.toNanos(Math.max(0, delayInMillis));
this.socketLimit = new Semaphore(socketLimit);
this.maxWorkersPerHost = maxWorkersPerHost;
}
public List<ScanResult> scan(ScanOptions target) {
return scanTargets(target.targets(), target.ports());
}
public List<ScanResult> scanTargets(List<String> targets, String ports) {
List<ScanResult> results = new ArrayList<>();
progressBar.start();
try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) {
List<Future<ScanResult>> futures = new ArrayList<>();
for (String target : targets) {
futures.add(executor.submit(() -> scanTarget(target, ports)));
}
futures.forEach((Future<ScanResult> f) -> {
try {
results.add(f.get());
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
} catch (ExecutionException e) {
System.out.printf("%s -> %s%n", e.getClass().getSimpleName(), e.getMessage());
}
});
}
progressBar.stop();
System.out.println("Peak concurrent connects: " + counter.max());
return results;
}
private ScanResult scanTarget(String target, String ports) {
PortRange portRange = new PortRange(ports);
AtomicLong portSlotFactory = new AtomicLong(System.nanoTime());
Semaphore maxWorkers = new Semaphore(maxWorkersPerHost);
BitSet openPorts = new BitSet(PortRange.MAX_PORT);
Progress progress = new Progress(target, portRange.getTotal(), new AtomicInteger(), new AtomicInteger());
progressBar.submit(progress);
try (ExecutorService executor = Executors.newVirtualThreadPerTaskExecutor()) {
List<Future<Integer>> futures = new ArrayList<>();
while (portRange.hasNext()) {
maxWorkers.acquireUninterruptibly();
final int currentPort = portRange.next();
futures.add(executor.submit(() -> {
try {
waitForSlot(portSlotFactory);
int port = scanPort(target, currentPort);
if (port != -1) {
progress.open().incrementAndGet();
}
return port;
} finally {
maxWorkers.release();
progress.done().incrementAndGet();
}
}));
}
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 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);
}
private int scanPort(String target, final int currentPort) {
return isTargetPortOpen(target, currentPort) ? currentPort : -1;
}
private void waitForSlot(AtomicLong scanSlotFactory) {
if (delayInNanos > 0) {
long slot = scanSlotFactory.getAndAdd(delayInNanos);
long wait = slot - System.nanoTime();
if (wait > 0)
LockSupport.parkNanos(wait);
}
}
private boolean isTargetPortOpen(String target, int port) {
socketLimit.acquireUninterruptibly();
counter.inc();
try (Socket socket = new Socket()) {
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.printf("%s -> %s", e.getClass().getSimpleName(), e.getMessage());
} finally {
counter.dec();
socketLimit.release();
}
return false;
}
}
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