DNSServer.java

/*
** This file is part of Filius, a network construction and simulation software.
** 
** Originally created at the University of Siegen, Institute "Didactics of
** Informatics and E-Learning" by a students' project group:
**     members (2006-2007): 
**         André Asschoff, Johannes Bade, Carsten Dittich, Thomas Gerding,
**         Nadja Haßler, Ernst Johannes Klebert, Michell Weyer
**     supervisors:
**         Stefan Freischlad (maintainer until 2009), Peer Stechert
** Project is maintained since 2010 by Christian Eibl <filius@c.fameibl.de>
 **         and Stefan Freischlad
** Filius is free software: you can redistribute it and/or modify
** it under the terms of the GNU General Public License as published by
** the Free Software Foundation, either version 2 of the License, or
** (at your option) version 3.
** 
** Filius is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied
** warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
** PURPOSE. See the GNU General Public License for more details.
** 
** You should have received a copy of the GNU General Public License
** along with Filius.  If not, see <http://www.gnu.org/licenses/>.
*/
package filius.software.dns;

import java.util.LinkedList;
import java.util.ListIterator;
import java.util.StringTokenizer;

import filius.Main;
import filius.software.clientserver.UDPServerAnwendung;
import filius.software.system.Datei;
import filius.software.system.Dateisystem;
import filius.software.transportschicht.Socket;

public class DNSServer extends UDPServerAnwendung {

	private LinkedList<ResourceRecord> records = new LinkedList<ResourceRecord>();

	public DNSServer() {
		super();
		Main.debug.println("INVOKED-2 ("+this.hashCode()+", T"+this.getId()+") "+getClass()+" (DNSServer), constr: DNSServer()");

		setPort(53);
	}

	public void starten() {
		Main.debug.println("INVOKED ("+this.hashCode()+", T"+this.getId()+") "+getClass()+" (DNSServer), starten()");
		super.starten();

		if (!getSystemSoftware().getDateisystem().dateiVorhanden("dns", "hosts")) {
			getSystemSoftware().getDateisystem().erstelleVerzeichnis("root", "dns");
		}

		initialisiereRecordListe();
	}

	public void beenden() {
		Main.debug.println("INVOKED ("+this.hashCode()+", T"+this.getId()+") "+getClass()+" (DNSServer), beenden()");
		super.beenden();
	}

	public LinkedList<ResourceRecord> holeResourceRecords() {
		this.initialisiereRecordListe();
		return records;
	}

	public void hinzuRecord(String domainname, String typ, String rdata) {
		Main.debug.println("INVOKED ("+this.hashCode()+", T"+this.getId()+") "+getClass()+" (DNSServer), hinzuRecord("+domainname+","+typ+","+rdata+")");
		ResourceRecord rr;
		
		rr = new ResourceRecord(domainname, typ, rdata);
		records.add(rr);
		this.schreibeRecordListe();
	}

	private void initialisiereRecordListe() {
		Main.debug.println("INVOKED ("+this.hashCode()+", T"+this.getId()+") "+getClass()+", initialisiereRecordListe()");
		Datei hosts;
		StringTokenizer tokenizer;
		String line;
		ResourceRecord rr;
		Dateisystem dateisystem;
		LinkedList<ResourceRecord> tmp;

		tmp = new LinkedList<ResourceRecord>();

		dateisystem = getSystemSoftware().getDateisystem();
		hosts = dateisystem.holeDatei(dateisystem.holeRootPfad()+Dateisystem.FILE_SEPARATOR+"dns"+Dateisystem.FILE_SEPARATOR+"hosts");

		if (hosts != null) {
			tokenizer = new StringTokenizer(hosts.getDateiInhalt(), "\n");

			while (tokenizer.hasMoreTokens()) {
				line = tokenizer.nextToken().trim();
				if (!line.equals("") && !(line.split(" ", 5).length<4)) {
				rr = new ResourceRecord(line);
				tmp.add(rr);
				}
			}
		}
		records = tmp;
	}

	private void schreibeRecordListe() {
		Main.debug.println("INVOKED ("+this.hashCode()+", T"+this.getId()+") "+getClass()+" (DNSServer), schreibeRecordListe()");
		Datei hosts;
		StringBuffer text;
		ListIterator<ResourceRecord> it;
		Dateisystem dateisystem;

		dateisystem = getSystemSoftware().getDateisystem();

		text = new StringBuffer();

		it = records.listIterator();
		while (it.hasNext()) {
			text.append(it.next().toString()+"\n");
		}

		hosts = new Datei();
		hosts.setDateiInhalt(text.toString());
		hosts.setName("hosts");
		
		dateisystem.speicherDatei(dateisystem.holeRootPfad()+Dateisystem.FILE_SEPARATOR+"dns", hosts);
	}

	public void changeSingleEntry(int recordIdx, int partIdx, String type, String newValue) {
		Main.debug.println("INVOKED ("+this.hashCode()+") "+getClass()+", changeSingleEntry("+recordIdx+","+partIdx+","+type+","+newValue+")");
		ListIterator<ResourceRecord> it = records.listIterator();
		ResourceRecord rrec = null;
		int countA = 0;
		while (it.hasNext()) {   // iterating whole list is necessary, since MX and A records are mixed in the records list! :-(
			rrec = it.next();
			if (rrec.getType().equals(type)) {
				countA++;
			}
			if (countA-1 == recordIdx) {    // found A entry with (filtered) index recordIdx
//				Main.debug.println("DEBUG ("+this.hashCode()+") "+getClass()+", changeSingleEntry:  aktuell: countA="+countA+", rrec="+rrec);
				if(partIdx == 0) {   // change URL
					rrec.setDomainname(newValue);
				}
				else if(partIdx == 3) {   // change IP
					rrec.setRdata(newValue);
				}
			}
		}
		this.schreibeRecordListe();
	}
	
	public void loescheResourceRecord(String domainname, String typ) {
		Main.debug.println("INVOKED ("+this.hashCode()+", T"+this.getId()+") "+getClass()+" (DNSServer), loescheResourceRecord("+domainname+","+typ+")");
		ResourceRecord rr;
		ListIterator<ResourceRecord> it;
		boolean fertig = false;

		it = records.listIterator();
		while (!fertig && it.hasNext()) {
			rr = (ResourceRecord)it.next();
			if (rr.getDomainname().equalsIgnoreCase(domainname)
					&& rr.getType().equals(typ)) {
				records.remove(rr);
				fertig = true;
			}
		}
		this.schreibeRecordListe();
	}

	public ResourceRecord holeRecord(String domainname, String typ) {
		Main.debug.println("INVOKED ("+this.hashCode()+", T"+this.getId()+") "+getClass()+" (DNSServer), holeRecord("+domainname+","+typ+")");
		
		for (ResourceRecord rr : records) {
			if (rr.getDomainname().equalsIgnoreCase(domainname)
					&& rr.getType().equals(typ)) {
				return rr;
			}
		}

		return null;
	}
	
	public ResourceRecord holeRecord(String domainname) {
		String domain;
		String[] parts = domainname.split("\\.");

		for (int i = 0; i < parts.length; i++) {
			domain = this.implodeDomain(parts, i);
			for (ResourceRecord rr : records) {
				if (rr.getDomainname().equalsIgnoreCase(domain)) {
					return rr;
				}
			}
		}
		
		return null;
	}
	
	private String implodeDomain(String[] parts, int start) {
		StringBuffer domain = new StringBuffer();
		for (int i=start; i<parts.length; i++) {
			domain.append(parts[i]);
			if (i < parts.length-1) {
				domain.append(".");
			}
		}
		return domain.toString();
	}

	protected void neuerMitarbeiter(Socket socket) {
		Main.debug.println("INVOKED ("+this.hashCode()+", T"+this.getId()+") "+getClass()+" (DNSServer), neuerMitarbeiter("+socket+")");
		DNSServerMitarbeiter dnsMitarbeiter;

		dnsMitarbeiter = new DNSServerMitarbeiter(this, socket);
		dnsMitarbeiter.starten();
		mitarbeiter.add(dnsMitarbeiter);

	}

}