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- package de.tudarmstadt.informatik.hostage.protocol;
- import java.util.ArrayList;
- import java.util.List;
- import de.tudarmstadt.informatik.hostage.commons.HelperUtils;
- import de.tudarmstadt.informatik.hostage.wrapper.Packet;
- /**
- * TELNET protocol. Implementation of RFC document 854.
- *
- * @author Wulf Pfeiffer
- */
- public class TELNET implements Protocol {
- /**
- * Represents the states of the protocol
- */
- private static enum STATE {
- NONE, OPEN, CLOSED, LOGIN, AUTHENTICATE, LOGGED_IN
- };
- /**
- * Denotes in which state the protocol is right now
- */
- private STATE state = STATE.NONE;
- /** user entered by the client */
- private static byte[] user;
- /** last command sent by the client */
- private byte[] command;
- /** name of the server */
- private static String serverName = HelperUtils.getRandomString(16, false);
- /** command line prefix */
- private static byte[] sessionToken = null;
- /** options requested by the server */
- private static final byte[] optionRequest = { (byte) 0xff, (byte) 0xfb,
- 0x03, // will suppress go ahead
- (byte) 0xff, (byte) 0xfb, 0x01 // will echo
- };
- // session token prefix, mid and suffix
- private static final byte[] sessionPrefix = { 0x1b, 0x5d, 0x30, 0x3b };
- private static final byte[] sessionMiddle = { 0x3a, 0x20, 0x7e, 0x07, 0x1b,
- 0x5b, 0x30, 0x31, 0x3b, 0x33, 0x32, 0x6d };
- private static final byte[] sessionSuffix = { 0x1b, 0x5b, 0x30, 0x30, 0x6d,
- 0x20, 0x1b, 0x5b, 0x30, 0x31, 0x3b, 0x33, 0x34, 0x6d, 0x7e, 0x20,
- 0x24, 0x1b, 0x5b, 0x30, 0x30, 0x6d, 0x20 };
- @Override
- public int getPort() {
- return 23;
- }
- @Override
- public boolean isClosed() {
- return (state == STATE.CLOSED);
- }
- @Override
- public boolean isSecure() {
- return false;
- }
- @Override
- public List<Packet> processMessage(Packet requestPacket) {
- byte[] request = null;
- if (requestPacket != null) {
- request = requestPacket.getBytes();
- }
- List<Packet> responsePackets = new ArrayList<Packet>();
- switch (state) {
- case NONE:
- responsePackets.add(new Packet(optionRequest));
- state = STATE.OPEN;
- break;
- case OPEN:
- if (request != null) {
- responsePackets.add(new Packet(getOptionResponse(request)));
- responsePackets.add(new Packet(serverName + " login: "));
- state = STATE.LOGIN;
- }
- break;
- case LOGIN:
- if (request == null)
- break;
- else if (checkForByte(request, (byte) 0x0d)) {
- if (request.length > 2) {
- byte[] buffer = new byte[request.length - 2];
- System.arraycopy(request, 0, buffer, 0, request.length - 2);
- user = HelperUtils.concat(user, buffer);
- responsePackets.add(new Packet(buffer));
- }
- responsePackets.add(new Packet("\r\n"));
- responsePackets.add(new Packet("Password: "));
- state = STATE.AUTHENTICATE;
- sessionToken = HelperUtils.concat(sessionPrefix, user,
- "@".getBytes(), serverName.getBytes(), sessionMiddle,
- user, "@".getBytes(), serverName.getBytes(),
- sessionSuffix);
- break;
- } else if (checkForByte(request, (byte) 0x7f) && user != null
- && user.length != 0) {
- byte[] tmp = new byte[user.length - 1];
- System.arraycopy(user, 0, tmp, 0, user.length - 1);
- user = tmp;
- responsePackets.add(new Packet("\b \b"));
- break;
- } else if (!checkForByte(request, (byte) 0xff)) {
- if (user == null)
- user = request;
- else
- user = HelperUtils.concat(user, request);
- responsePackets.add(requestPacket);
- }
- break;
- case AUTHENTICATE:
- if (request == null)
- break;
- else if (checkForByte(request, (byte) 0x0d)) {
- responsePackets.add(new Packet("\r\n"));
- responsePackets.add(new Packet(sessionToken));
- state = STATE.LOGGED_IN;
- } else if (checkForByte(request, (byte) 0x7f)) {
- responsePackets.add(new Packet("\b \b"));
- }
- break;
- case LOGGED_IN:
- if (request == null)
- break;
- else if (checkForByte(request, (byte) 0x0d)) {
- if (request.length > 2) {
- byte[] buffer = new byte[request.length - 2];
- System.arraycopy(request, 0, buffer, 0, request.length - 2);
- command = HelperUtils.concat(command, buffer);
- responsePackets.add(new Packet(buffer));
- }
- if (command == null) {
- responsePackets.add(new Packet("\r\n"));
- responsePackets.add(new Packet(sessionToken));
- } else if (new String(command).contains("exit")) {
- responsePackets.add(new Packet("\r\nlogout\r\n"));
- state = STATE.CLOSED;
- } else {
- String bash = "\r\n-bash: " + new String(command)
- + ": command not found";
- responsePackets.add(new Packet(bash));
- responsePackets.add(new Packet("\r\n"));
- responsePackets.add(new Packet(sessionToken));
- command = null;
- }
- } else if (checkForByte(request, (byte) 0x7f) && command != null
- && command.length != 0) {
- byte[] tmp = new byte[command.length - 1];
- System.arraycopy(command, 0, tmp, 0, command.length - 1);
- command = tmp;
- responsePackets.add(new Packet("\b \b"));
- break;
- } else if (!checkForByte(request, (byte) 0xff)) {
- if (command == null)
- command = request;
- else
- command = HelperUtils.concat(command, request);
- responsePackets.add(requestPacket);
- }
- break;
- default:
- responsePackets.add(new Packet("\r\nlogout\r\n"));
- state = STATE.CLOSED;
- break;
- }
- return responsePackets;
- }
- @Override
- public String toString() {
- return "TELNET";
- }
- @Override
- public TALK_FIRST whoTalksFirst() {
- return TALK_FIRST.SERVER;
- }
- /**
- * Checks a byte array for occurence of one byte.
- *
- * @param bytes
- * byte array that is checked.
- * @param b
- * searched byte.
- * @return true if the byte was found, else false.
- */
- private boolean checkForByte(byte[] bytes, byte b) {
- for (byte oneByte : bytes) {
- if (oneByte == b)
- return true;
- }
- return false;
- }
- /**
- * Determines which options that are requested by the client will be done
- * and which not
- *
- * @param request
- * requested options
- * @return accepted and unaccepted options
- */
- private byte[] getOptionResponse(byte[] request) {
- List<byte[]> responseList = new ArrayList<byte[]>();
- byte[] requestInverse;
- for (int i = 0; i < request.length - 2; i += 3) {
- if (request[i] == (byte) 0xff && request[i + 2] != 0x03
- && request[i + 2] != 0x01) {
- requestInverse = new byte[3];
- requestInverse[0] = request[i];
- requestInverse[1] = request[i + 1] == (byte) 0xfd ? (byte) 0xfc
- : (byte) 0xfe;
- requestInverse[2] = request[i + 2];
- responseList.add(requestInverse);
- }
- }
- byte[] optionResponse = new byte[0];
- for (byte[] response : responseList) {
- optionResponse = HelperUtils.concat(optionResponse, response);
- }
- return optionResponse;
- }
- }
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