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Finished (hopefully)

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Victor Hans-Georg Waitz 2025-10-21 21:46:57 +02:00
parent 9c9647b992
commit e7c4f781a2
5 changed files with 113 additions and 64 deletions
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106
vs.pu01/src/main/java/vs/Client.java
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@ -5,37 +5,94 @@ import java.net.DatagramPacket;
import java.net.DatagramSocket; import java.net.DatagramSocket;
import java.net.InetAddress; import java.net.InetAddress;
import java.net.SocketAddress; import java.net.SocketAddress;
import java.util.ArrayList;
import javax.print.attribute.standard.Severity;
import vs.AsciiChars.L032;
import vs.AsciiChars.L048;
import vs.AsciiChars.L128;
import vs.AsciiChars.L255;
import vs.SyslogMessage.Facility;
import vs.SyslogMessage.TextMessage;
public class Client { public class Client {
private static final int BUFSIZE = 512; private static final int BUFSIZE = 512;
private static final String BROADCAST_ADDRESS = "255.255.255.255";
private static final int DISCOVERY_PORT = 8888;
private static final int SYSLOG_PORT = 514;
static DatagramPacket packetOutDisover = new DatagramPacket(new byte[BUFSIZE], BUFSIZE);
static DatagramPacket packetInOffer = new DatagramPacket(new byte[BUFSIZE], BUFSIZE);
static DatagramPacket packetOutRequest = new DatagramPacket(new byte[BUFSIZE], BUFSIZE);
static DatagramPacket packetInAcknowledge = new DatagramPacket(new byte[BUFSIZE], BUFSIZE);
static DatagramPacket packetOutSyslog = new DatagramPacket(new byte[BUFSIZE], BUFSIZE);
public static void main(String[] args) { public static void main(String[] args) {
try (DatagramSocket socket = new DatagramSocket()) { try (DatagramSocket socket = new DatagramSocket()) {
socket.setBroadcast(true); socket.setBroadcast(true);
//? Get Server IP //? SEND DISOVERY
String message = "DISCOVER_SERVERS"; String messageString = "DISCOVER";
byte[] buffer = message.getBytes(); byte[] message = messageString.getBytes();
InetAddress broadcastAddress = InetAddress.getByName("255.255.255.255"); packetOutDisover.setAddress(InetAddress.getByName(BROADCAST_ADDRESS));
int discoveryPort = 8888; packetOutDisover.setPort(DISCOVERY_PORT);
packetOutDisover.setData(message);
packetOutDisover.setLength(message.length);
DatagramPacket packetOutDisover = new DatagramPacket(buffer, buffer.length, broadcastAddress, discoveryPort);
socket.send(packetOutDisover); socket.send(packetOutDisover);
//? Got server IP //? GET OFFER + SEND REQUEST
DatagramPacket packetIn = new DatagramPacket(new byte[BUFSIZE], BUFSIZE); socket.receive(packetInOffer);
socket.receive(packetIn); String receivedOffer = new String(packetInOffer.getData(), 0, packetInOffer.getLength());
System.out.println("Received Offer: " + receivedOffer);
System.out.println("Recieved Server IP " + packetIn.getSocketAddress()); messageString = "REQUEST";
message = messageString.getBytes();
packetOutRequest.setAddress(packetInOffer.getAddress());
packetOutRequest.setPort(DISCOVERY_PORT);
packetOutRequest.setData(message);
packetOutRequest.setLength(message.length);
socket.send(packetOutRequest);
//? GET ACKNOWLEDGE
socket.receive(packetInAcknowledge);
String receivedAckowledge = new String(packetInAcknowledge.getData(), 0, packetInAcknowledge.getLength());
System.out.println("Received Acknowledge: " + receivedAckowledge);
InetAddress syslogServerAddress = packetInAcknowledge.getAddress();
//? SEND SYSLOG
System.out.println("Recieved Server IP " + syslogServerAddress);
DatagramPacket packetOutSyslog = new DatagramPacket(new byte[BUFSIZE], BUFSIZE); DatagramPacket packetOutSyslog = new DatagramPacket(new byte[BUFSIZE], BUFSIZE);
packetOutSyslog.setAddress(packetIn.getAddress()); packetOutSyslog.setAddress(syslogServerAddress);
int syslogPort = 514; packetOutSyslog.setPort(SYSLOG_PORT);
packetOutSyslog.setPort(syslogPort);
String syslogMessage = formatSyslogMessage(message); TextMessage textMessage = new TextMessage("message");
byte[] syslogMessageBytes = syslogMessage.getBytes();
SyslogMessage syslogMessage = new SyslogMessage(
SyslogMessage.Facility.USER,
SyslogMessage.Severity.INFORMATIONAL,
new L255("192.168.2.100"),
new L048("java"),
new L128("1"),
new L032("1"),
new StructuredData(new ArrayList<>()),
textMessage
);
String syslogMessageString = syslogMessage.toString();
byte[] syslogMessageBytes = syslogMessageString.getBytes();
packetOutSyslog.setData(syslogMessageBytes); packetOutSyslog.setData(syslogMessageBytes);
packetOutSyslog.setLength(syslogMessageBytes.length); packetOutSyslog.setLength(syslogMessageBytes.length);
@ -48,23 +105,4 @@ public class Client {
e.printStackTrace(); e.printStackTrace();
} }
} }
private static String formatSyslogMessage(String message) {
// Basic RFC 5424 format without structured data
// <PRI>TIMESTAMP HOSTNAME APPNAME PID MESSAGEID [STRUCTURED-DATA] MSG
// Since you ignore structured data, we skip that part
int facility = 16; // local0
int severity = 6; // informational
int pri = (facility * 8) + severity;
String timestamp = java.time.Instant.now().toString();
String hostname = "test-client";
String appName = "SyslogTest";
String procId = "12345";
String msgId = "TEST001";
return String.format("<%d>1 %s %s %s %s %s - %s",
pri, timestamp, hostname, appName, procId, msgId, message);
}
} }

12
vs.pu01/src/main/java/vs/DiscoveryServer.java
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@ -4,11 +4,12 @@ import java.net.DatagramPacket;
import java.net.DatagramSocket; import java.net.DatagramSocket;
import java.net.InetAddress; import java.net.InetAddress;
// Discovery-Responder (ähnlich DHCP-Verhalten, aber minimal):
// - Hört auf UDP/8888 und akzeptiert Broadcasts
// - Antwortet mit leerem UDP-Paket direkt an den Absender
// - Client kann aus der Quell-IP der Antwort die Server-IP ermitteln
public class DiscoveryServer implements Runnable { public class DiscoveryServer implements Runnable {
private static final int BUFSIZE = 512;
DatagramPacket packetInDiscover = new DatagramPacket(new byte[BUFSIZE], BUFSIZE);
private final int port; private final int port;
public DiscoveryServer(int port) { public DiscoveryServer(int port) {
@ -18,8 +19,9 @@ public class DiscoveryServer implements Runnable {
@Override @Override
public void run() { public void run() {
System.out.println("Discovery running on " + port); System.out.println("Discovery running on " + port);
try (DatagramSocket discoverySocket = new DatagramSocket(port)) { try (DatagramSocket discoverySocket = new DatagramSocket(port)) {
discoverySocket.setReuseAddress(true); // discoverySocket.setReuseAddress(true);
discoverySocket.setBroadcast(true); discoverySocket.setBroadcast(true);
while (true) { while (true) {

12
vs.pu01/src/main/java/vs/Main.java
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@ -1,17 +1,11 @@
package vs; package vs;
// Einstiegspunkt der Anwendung:
// - Startet zwei Threads: Syslog-UDP-Server (Port 514) und Discovery-Server (Port 8888)
// - Erfüllt die Vorgaben: UDP-only, keine TLS, zwei Sockets, Konsolen-Ausgabe
public class Main { public class Main {
private static final int SYSLOG_PORT = 514; // Standard-Syslog-Port (UDP) private static final int SYSLOG_PORT = 514;
private static final int DISCOVERY_PORT = 8888; // Port für Auto-Discovery private static final int DISCOVERY_PORT = 8888;
public static void main(String[] args) { public static void main(String[] args) {
// System.out.println("Syslog server is running on UDP/514 and discovery on UDP/8888...");
// Thread 1: Empfängt Syslog-Nachrichten und druckt Sender-IP + Nachricht
new Thread(new SyslogUdpServer(SYSLOG_PORT), "syslog").start();
// Thread 2: Beantwortet Broadcast-Anfragen und verrät so die Server-IP
new Thread(new DiscoveryServer(DISCOVERY_PORT), "discovery").start(); new Thread(new DiscoveryServer(DISCOVERY_PORT), "discovery").start();
new Thread(new SyslogUdpServer(SYSLOG_PORT), "syslog").start();
} }
} }

29
vs.pu01/src/main/java/vs/Server.java
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@ -8,7 +8,7 @@ import java.util.concurrent.Executors;
public class Server { public class Server {
private static final int BUFFSIZE = 512; //? Maybe andere Größe private static final int BUFFSIZE = 512;
private static final ExecutorService executor = Executors.newFixedThreadPool(2); private static final ExecutorService executor = Executors.newFixedThreadPool(2);
public interface PacketHandler { public interface PacketHandler {
@ -47,7 +47,14 @@ public class Server {
static class SyslogHandler implements PacketHandler { static class SyslogHandler implements PacketHandler {
@Override @Override
public void handlePacket(DatagramSocket socket, DatagramPacket packetIn, String serviceName) { public void handlePacket(DatagramSocket socket, DatagramPacket packetIn, String serviceName) {
final int MAX_LENGTH = 2048;
if (packetIn.getLength() > MAX_LENGTH){
return;
}
String receivedSyslog = new String(packetIn.getData(), 0, packetIn.getLength());
System.out.println(receivedSyslog);
} }
} }
@ -57,10 +64,24 @@ public class Server {
DatagramPacket packetOut = new DatagramPacket(new byte[BUFFSIZE], BUFFSIZE); DatagramPacket packetOut = new DatagramPacket(new byte[BUFFSIZE], BUFFSIZE);
packetOut.setSocketAddress(packetIn.getSocketAddress()); packetOut.setSocketAddress(packetIn.getSocketAddress());
packetOut.setData(new byte[0]);
packetOut.setLength(0);
System.out.println("Found client, responding"); String receivedDataString = new String(packetIn.getData(), 0, packetIn.getLength());
// System.out.println("Discorvery Packet: " + receivedDataString);
byte[] repsonseMessage;
if (receivedDataString.equals("DISCOVER")) {
repsonseMessage = "OFFER".getBytes();
}
else if (receivedDataString.equals("REQUEST")) {
repsonseMessage = "ACKNOWLEDGE".getBytes();
// System.out.println("Acknowledged client: " + packetIn.getSocketAddress());
}
else {
repsonseMessage = "ERROR".getBytes();
}
packetOut.setData(repsonseMessage);
packetOut.setLength(repsonseMessage.length);
socket.send(packetOut); socket.send(packetOut);
} }

18
vs.pu01/src/main/java/vs/SyslogUdpServer.java
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@ -4,13 +4,9 @@ import java.net.DatagramPacket;
import java.net.DatagramSocket; import java.net.DatagramSocket;
import java.net.InetAddress; import java.net.InetAddress;
// UDP-Syslog-Empfänger:
// - Hört auf Port 514 (UDP), kein TLS
// - Prüft maximale Nachrichtenlänge (hier 1024 Bytes, RFC 5426 Empfehlung)
// - Gibt pro Nachricht die Absender-IP:Port und den Text auf der Konsole aus
public class SyslogUdpServer implements Runnable { public class SyslogUdpServer implements Runnable {
private final int port; private final int port;
// Maximale Länge (vereinfachte Vorgabe; UDP-Empfänger sollten ~1024 Bytes unterstützen)
private static final int MAX_MESSAGE_LENGTH = 1024; private static final int MAX_MESSAGE_LENGTH = 1024;
public SyslogUdpServer(int port) { public SyslogUdpServer(int port) {
@ -19,20 +15,18 @@ public class SyslogUdpServer implements Runnable {
@Override @Override
public void run() { public void run() {
System.out.println("Syslog running on " + port); System.out.println("Syslog running on " + port + "\n");
// Socket öffnen und auf allen Interfaces an Port 514 lauschen
try (DatagramSocket syslogSocket = new DatagramSocket(port)) { try (DatagramSocket syslogSocket = new DatagramSocket(port)) {
syslogSocket.setReuseAddress(true); // erlaubt schnelles Neu-Starten syslogSocket.setReuseAddress(true);
byte[] buffer = new byte[MAX_MESSAGE_LENGTH + 1]; // +1 als einfache Oversize-Erkennung byte[] buffer = new byte[MAX_MESSAGE_LENGTH + 1];
while (true) { while (true) {
DatagramPacket packet = new DatagramPacket(buffer, buffer.length); DatagramPacket packet = new DatagramPacket(buffer, buffer.length);
syslogSocket.receive(packet); // UDP-Paket empfangen syslogSocket.receive(packet);
System.out.println("SYSLOG from " + packet.getSocketAddress());
int len = packet.getLength(); int len = packet.getLength();
InetAddress clientAddress = packet.getAddress(); InetAddress clientAddress = packet.getAddress();
// Zu lange Nachrichten verwerfen (Aufgabenforderung: Länge prüfen)
if (len > MAX_MESSAGE_LENGTH) { if (len > MAX_MESSAGE_LENGTH) {
System.err.println("Dropped oversized UDP syslog (" + len + " > " + MAX_MESSAGE_LENGTH System.err.println("Dropped oversized UDP syslog (" + len + " > " + MAX_MESSAGE_LENGTH
+ ") from " + clientAddress.getHostAddress() + ":" + packet.getPort()); + ") from " + clientAddress.getHostAddress() + ":" + packet.getPort());