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Java two threads work with the same data (one get, one set)

I'm taking my first steps with Java Sockets and Threads.
I want to try make synchonized connection with serwer where multiple threades adds their request to the queue and signle thread send all this request. In the meantime other threads wait for there resoults.
How it's work:
Client ask servert to log in by caling method
User user = logIn("sdasd");
public User logIn(String name){
System.out.println("!Log in");
//Function create request
RequestHandler<User> request = new RequestHandler<>("logIn", name, out, results);
//Request is added to queue
requestQueue.addLast(request);
RequestStatus status;
//Thread who call this function wait for request to be handle (changed status)
while (true){
status = request.getStatus();
System.out.println(status);
if (status == RequestStatus.SUCCESSFUL) {
System.out.println("Try to get result: ");
User user = request.result();
System.out.println(user.getName());
return request.result();
}
if(status == RequestStatus.FAILED) {
return null;
}
}
}
In the meantime other thread send request to server:
new Thread(new Runnable() {
#Override
public void run() {
while(isConnected()){
//is request to be handle?
if(requestQueue.size() != 0){
//remove request form queue
RequestHandler request = (RequestHandler) requestQueue.removeFirst();
//change request status
request.setStatus(RequestStatus.IN_PROGRESS);
System.out.println("!Request: ");
System.out.println(request.getStatus());
//process request
request.request();
//change request status to finished
request.setStatus(RequestStatus.SUCCESSFUL);
System.out.print("!Request end: ");
System.out.println(request.getStatus());
}
}
Iterator<Request> iterator = requestQueue.iterator();
for (Iterator<Request> it = iterator; it.hasNext(); ) {
Request request = it.next();
request.setStatus(RequestStatus.FAILED);
}
}
}).start();
Inside class RequestHandler is process this code:
#Override
public void request() {
try {
//send commend
out.writeObject(requestCommend);
//wait for result (other thread handle this functionality)
while(!results.containsKey(commend)){}
//attach result
result = (T) results.remove(commend);
} catch (IOException e) {
e.printStackTrace();
}
}
When the request is send to the server other thread wait for response for the server and add result to the HashMap:
new Thread(new Runnable() {
#Override
public void run() {
while(isConnected()) {
try {
String commend = (String) in.readObject();
if(commend.charAt(0) == '#') { // # mean its result of request
Object object = in.readObject();
//This is debug case to see everything work properly
if(object == null){
System.out.println("!I am null");
}else{
System.out.println("I am user: " +((User) object).getName());
}
System.out.println(commend);
results.put(commend, object);
}
} catch (IOException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
}
}).start();
This is it. Required code for this question:
public class ServerConnection extends Socket{
public static final int PORT = 8888;
private ObjectInputStream in;
private ObjectOutputStream out;
private LinkedList<Request> requestQueue;
private ConcurrentHashMap<String, Object> results;
public ServerConnection() throws IOException{
super("localhost", PORT);
System.out.println("Connected to the server.");
in = new ObjectInputStream(getInputStream());
out = new ObjectOutputStream(getOutputStream());
requestQueue = new LinkedList<>();
results = new ConcurrentHashMap<>();
new Thread(new Runnable() {
#Override
public void run() {
while(isConnected()){
if(requestQueue.size() != 0){
RequestHandler request = (RequestHandler) requestQueue.removeFirst();
request.setStatus(RequestStatus.IN_PROGRESS);
System.out.println("!Request: ");
System.out.println(request.getStatus());
request.request();
request.setStatus(RequestStatus.SUCCESSFUL);
System.out.print("!Request end: ");
System.out.println(request.getStatus());
}
}
Iterator<Request> iterator = requestQueue.iterator();
for (Iterator<Request> it = iterator; it.hasNext(); ) {
Request request = it.next();
request.setStatus(RequestStatus.FAILED);
}
}
}).start();
new Thread(new Runnable() {
#Override
public void run() {
while(isConnected()) {
try {
String commend = (String) in.readObject();
if(commend.charAt(0) == '#') { // # mean its result of request
Object object = in.readObject();
//This is debug case
if(object == null){
System.out.println("!I am null");
}else{
System.out.println("I am user: " +((User) object).getName());
}
System.out.println(commend);
results.put(commend, object);
}
} catch (IOException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}
}
}).start();
}
public User logIn(String name){
System.out.println("!Log in");
RequestHandler<User> request = new RequestHandler<>("logIn", name, out, results);
requestQueue.addLast(request);
RequestStatus status;
while (true){
status = request.getStatus();
System.out.println(status);
if (status == RequestStatus.SUCCESSFUL) {
System.out.println("Try to get result: ");
User user = request.result();
System.out.println(user.getName());
return request.result();
}
if(status == RequestStatus.FAILED) {
return null;
}
}
}
public ArrayList<Room> getListOfRooms(){
Request<ArrayList<Room>> request = new RequestHandler<>("listOfRooms", out, results);
requestQueue.addLast(request);
while (true){
RequestStatus status = request.getStatus();
if (status == RequestStatus.SUCCESSFUL)
return request.result();
if(status == RequestStatus.FAILED) {
return null;
}
}
}
}
RequestHandler looks like this:
public class RequestHandler<T> implements Request<T>{
private T result;
private RequestStatus status = RequestStatus.NEW;
private ObjectOutputStream out;
private String commend;
private String requestCommend;
private ConcurrentHashMap<String, Object> results;
public RequestHandler(String commend, String parameters, ObjectOutputStream out, ConcurrentHashMap<String, Object> results) {
this.commend = "#" + commend;
this.requestCommend = "?" + commend + ":" + parameters;
this.out = out;
this.results = results;
}
public RequestHandler(String commend, ObjectOutputStream out, ConcurrentHashMap<String, Object> results) {
this.commend = "#" + commend;
this.requestCommend = "?" + commend;
this.out = out;
this.results = results;
}
#Override
public void request() {
try {
out.writeObject(requestCommend);
while(!results.containsKey(commend)){}
result = (T) results.remove(commend);
} catch (IOException e) {
e.printStackTrace();
}
}
#Override
public T result() {
return result;
}
#Override
public RequestStatus getStatus() {
return status;
}
#Override
public void setStatus(RequestStatus status) {
this.status = status;
}
}
The output looks like this WHEN ITS WORK:
Connected to the server.
!Log in
NEW
IN_PROGRESS
...
IN_PROGRESS
!Request: IN_PROGRESS
IN_PROGRESS
...
IN_PROGRESS
I am user: sdsad
#logIn
IN_PROGRESS
IN_PROGRESS
SUCCESSFUL
!Request end: SUCCESSFUL
Try to get result:
sdsad
But when I COMMENT one debug msg I got this:
Connected to the server.
!Log in
!Request: IN_PROGRESS
I am user: dfdsfsdf4324
#logIn
!Request end: SUCCESSFUL
And the loop while(true) never end becouse I got always status IN_PROGRESS.
That's why I want to ask you why it's happen? Is Java have some weird way to optimalize output of functions to make is faster and is it thinking if it was reapet milion times so it has to be this state always?

Confusion with Synchronization and inter thread communication

I've been given this question and I've been trying since days but I'm not able to get the correct output. Any help would be appreciated.
Develop a simple chat application between two users using Send-Wait-Receive Protocol:
Once a user sends a message, he waits until a message is received from the other user. The users are "User1" and "User2".
At initial stage of application, User1 is in sending mode and User2 is in receiving mode. These two users are sending and receiving the messages alternatively.
-Create a Chat class with two methods: sendMessage and recvMessage
-Create two threads to represent two users,User1 and User2.
-Use Interthread communication to exchange messages.
-No need to maintain any chat history.
OUTPUT:
User1(User2):HI
User2(User1):HI
User2(User1):Hello
User1(User2):Hello
class Chat{
Scanner sc=new Scanner(System.in);
String message;
ArrayList<String> user1 = new ArrayList<String>();
ArrayList<String> user2 = new ArrayList<String>();
boolean sendMode = true;
String name = "";
String otherName = "";
synchronized void recvMessage(){
name = Thread.currentThread().getName();
while(sendMode) {
try{
wait();
}catch(InterruptedException e){
System.out.println("InterruptedException caught");
}
}
System.out.println(name);
if (name.contentEquals("User1")) {
otherName="User2";
}
else {
otherName="User1";
}
System.out.println(name+"("+otherName+"):" + message);
sendMode=true;
System.out.println("rcv");
notify();
}
synchronized void sendMessage(){
name = Thread.currentThread().getName();
while(!sendMode) {
try{
wait();
}catch(InterruptedException e){
System.out.println("InterruptedException caught");
}
}
System.out.println(name);
if (name.contentEquals("User1")) {
otherName="User2";
}
else {
otherName="User1";
}
System.out.print(name+"("+otherName+"):");
message=sc.next();
if(name.contains("User1")) {
user1.add(message);
}
else {
user2.add(message);
}
System.out.println("send");
sendMode=false;
notify();
}
}
class Person1 implements Runnable{
Chat ex;
public Person1(Chat ex) {
this.ex = ex;
Thread u2=new Thread(this, "User1");
u2.start();
}
public void run() {
while(true) {
ex.sendMessage();
}
}
}
class Person2 implements Runnable{
Chat ex;
public Person2(Chat ex) {
this.ex=ex;
Thread u1=new Thread(this, "User2");
u1.start();
}
public void run() {
while(true) {
ex.recvMessage();
}
}
}
class Main{
public static void main(String args[])
{
Chat ex =new Chat();
new Person1(ex);
new Person2(ex);
}
}
the output I'm getting is:
User1(User2):hi
User2(User1):hi
User2(User1):hello
User1(User2):hello
User2(User1):what's up
User1(User2):what's
User2(User1):User1(User2):up
User2(User1):
Basically the threads are not in doing their job in order. The first 4 lines of output are right. But after that, it's always user2 sending the message and user1 receiving it.
Please help me out.

There is two issues with your code first is that you are using:
message=sc.next();
and instead you should be using:
message=sc.nextLine();
Using next() will only return what comes before the delimiter
(defaults to whitespace). nextLine() automatically moves the scanner
down after returning the current line.
From this SO thread.
That is why for the first inputs without spaces it works fine, but as soon as you send a string with spaces:
what's up
you ran into problems.
The second part is that with your current design only one of the threads send and another receives. For having both communication with each other instead of a monologue, I would suggest to do something like:
class Chat{
Scanner sc=new Scanner(System.in);
String message;
final Object rec = new Object();
final Object send = new Object();
boolean msg_send = false;
boolean msg_recv = false;
void recvMessage(){
synchronized (send){
while(!msg_send) {
try{
send.wait();
}catch(InterruptedException e){
System.out.println("InterruptedException caught");
}
}
msg_send = false;
}
synchronized (rec) {
String name = Thread.currentThread().getName();
System.out.println(name);
String otherName = name.contentEquals("User1") ? "User2" : "User1";
System.out.println(name + "(" + otherName + "):" + message);
System.out.println("rcv");
msg_recv = true;
rec.notify();
}
}
void sendMessage(){
synchronized (send) {
String name = Thread.currentThread().getName();
System.out.println(name);
String otherName = name.contentEquals("User1") ? "User2" : "User1";
System.out.print(name + "(" + otherName + "):");
message = sc.nextLine();
System.out.println("send");
msg_send = true;
send.notify();
}
synchronized (rec) {
while (!msg_recv) {
try {
rec.wait();
} catch (InterruptedException e) {
System.out.println("InterruptedException caught");
}
}
msg_recv = false;
}
}
}
class Person1 implements Runnable{
Chat ex;
public Person1(Chat ex) {
this.ex = ex;
Thread u2=new Thread(this, "User1");
u2.start();
}
public void run() {
while(true) {
ex.sendMessage();
ex.recvMessage();
}
}
}
class Person2 implements Runnable{
Chat ex;
public Person2(Chat ex) {
this.ex=ex;
Thread u1=new Thread(this, "User2");
u1.start();
}
public void run() {
while(true) {
ex.recvMessage();
ex.sendMessage();
}
}
}
class Main{
public static void main(String args[])
{
Chat ex =new Chat();
new Person1(ex);
new Person2(ex);
}
}
Waiting and notifying using two objects representing when the message was received and send:
final Object rec = new Object();
final Object send = new Object();
Then you need the reason about when should you synchronize on one or the other object.

long pulling bot telegram fail with making a test

So, guys, I'm doing a telegram long polling bot, via Java, via telegram bots API.
I made an integer for a test to do +1 after good answer and nothing with integer, while answer is wrong.
public void onUpdateReceived(Update update) {
int i=0;
on the very beginning of on update receive.
and when a user starts test he sees a markup keyboard with the first question and 4 answers
else if (message_text.equals("test"))
{
SendMessage message = new SendMessage() // Create a message object object
.setChatId(chat_id)
.setText("Test");
// Create ReplyKeyboardMarkup object
ReplyKeyboardMarkup keyboardMarkup = new ReplyKeyboardMarkup();
// Create the keyboard (list of keyboard rows)
List<KeyboardRow> keyboard = new ArrayList<>();
// Create a keyboard row
KeyboardRow row = new KeyboardRow();
// Set each button, you can also use KeyboardButton objects if you need something else than text
row.add("1. М");
row.add("2. end");
// Add the first row to the keyboard
keyboard.add(row);
// Create another keyboard row
row = new KeyboardRow();
row.add("3. К");
row.add("4. Т");
keyboard.add(row);
// Set the keyboard to the markup
keyboardMarkup.setKeyboard(keyboard);
// Add it to the message
message.setReplyMarkup(keyboardMarkup);
try
{
sendMessage(message); // Call method to send the photo
}
catch (TelegramApiException e)
{
e.printStackTrace();
}
}
else if (message_text.equals("1. М"))
{
i=i+1;
SendMessage message = new SendMessage() // Create a message object object
.setChatId(chat_id)
.setText("Test");
ReplyKeyboardMarkup keyboardMarkup = new ReplyKeyboardMarkup();
List<KeyboardRow> keyboard = new ArrayList<>();
KeyboardRow row = new KeyboardRow();
row.add("1. М");
row.add("2. end");
keyboard.add(row);
row = new KeyboardRow();
row.add("3. К");
row.add("4. Т");
keyboard.add(row);
keyboardMarkup.setKeyboard(keyboard);
message.setReplyMarkup(keyboardMarkup);
try
{
sendMessage(message);
}
catch (TelegramApiException e)
{
e.printStackTrace();
}
}
else if (message_text.equals("2. end"))
{
if (i == 1) {
SendMessage message = new SendMessage()
.setChatId(chat_id)
.setText("roflan");
try {
sendMessage(message);
} catch (TelegramApiException e) {
e.printStackTrace();
}
}
}
if I will write "!=1" , after"2. end" it always shows the result. It does not matter how many time user answer the first button, i+1 doesn't work. Where is a problem with my logic?

Let's forget about Telegram API just to watch what is happening with your int i variable.
Everytime the onUpdateReceived() is called, int i is declaring inside this method and initialising with value 0.
It looks like this
public class Scope {
public static void main(String[] args) {
System.out.println(getI());
System.out.println(getI());
}
private static int getI() {
int i = 0;
i++;
return i;
}
}
The output will be
1
1
To make your program work as you expect you should declare int i outside of onUpdateReceived() scope. The most obvious way is creating a static variable.
public class Scope {
public static void main(String[] args) {
System.out.println(getI());
System.out.println(getI());
System.out.println(getI());
System.out.println(getI());
}
private static int i = 0;
private static int getI() {
i++;
return i;
}
}
The output will be
1
2
3
4
So, now your code should look like this one
public class Bot extends TelegramLongPollingBot {
private static int i = 0;
public void onUpdateReceived() {
/*...*/
else if (update.hasMessage() && update.getMessage().hasText() && update.getMessage().getText().equals("1. M")) {
i++;
} else if (update.hasMessage() && update.getMessage().hasText() && update.getMessage().getText().equals("1. end")) {
System.out.println(i);
}
/*...*/
}
public String getBotToken() {
return "...";
}
public String getBotUsername() {
return "...";
}
}

JSP - Running a program with main method and nested static class

I'm a novice when it comes to JSPs and JAVA.
How do I get the output from the below code to display on a jsp, considering that it runs everything from the main and contains non-public methods, a nested static class etc?
I know that we are not supposed to use java code on jsp but my first step in this proof on concept exercise is to get the code running and returning data from a backend then I can set about using EL etc.
I can run the program, with the correct config settings, from within Eclipse and all works fine with the output appearing on the console but I'm really not sure how to access it from within a jsp.
How do I access the static class and static methods from a jsp if they aren't public?
All help greatly appreciated.
public class CustomDestinationDataProvider
{
static class MyDestinationDataProvider implements DestinationDataProvider
{
private DestinationDataEventListener eL;
private HashMap<String, Properties> secureDBStorage = new HashMap<String, Properties>();
public Properties getDestinationProperties(String destinationName)
{
try
{
//read the destination from DB
Properties p = secureDBStorage.get(destinationName);
if(p!=null)
{
//check if all is correct, for example
if(p.isEmpty())
throw new DataProviderException(DataProviderException.Reason.INVALID_CONFIGURATION, "destination configuration is incorrect", null);
return p;
}
return null;
}
catch(RuntimeException re)
{
throw new DataProviderException(DataProviderException.Reason.INTERNAL_ERROR, re);
}
}
public void setDestinationDataEventListener(DestinationDataEventListener eventListener)
{
this.eL = eventListener;
}
public boolean supportsEvents()
{
return true;
}
//implementation that saves the properties in a very secure way
void changeProperties(String destName, Properties properties)
{
synchronized(secureDBStorage)
{
if(properties==null)
{
if(secureDBStorage.remove(destName)!=null)
eL.deleted(destName);
}
else
{
secureDBStorage.put(destName, properties);
eL.updated(destName); // create or updated
}
}
}
} // end of MyDestinationDataProvider
//business logic
void executeCalls(String destName)
{
JCoDestination dest;
try
{
dest = JCoDestinationManager.getDestination(destName);
dest.ping();
System.out.println("Destination " + destName + " works");
step4WorkWithTable(dest);
}
catch(JCoException e)
{
e.printStackTrace();
System.out.println("Execution on destination " + destName+ " failed");
}
}
static Properties getDestinationPropertiesFromUI()
{
//adapt parameters in order to configure a valid destination
Properties connectProperties = new Properties();
// Add code here to set config settings
return connectProperties;
}
public static void main(String[] args)
{
MyDestinationDataProvider myProvider = new MyDestinationDataProvider();
//register the provider with the JCo environment;
//catch IllegalStateException if an instance is already registered
try
{
com.sap.conn.jco.ext.Environment.registerDestinationDataProvider(myProvider);
}
catch(IllegalStateException providerAlreadyRegisteredException)
{
//somebody else registered its implementation,
//stop the execution
throw new Error(providerAlreadyRegisteredException);
}
String destName = "????";
CustomDestinationDataProvider test = new CustomDestinationDataProvider();
//set properties for the destination and ...
myProvider.changeProperties(destName, getDestinationPropertiesFromUI());
//... work with it
test.executeCalls(destName);
}
public static void step4WorkWithTable(JCoDestination dest) throws JCoException
{
JCoFunction function = dest.getRepository().getFunction("BAPI_COMPANYCODE_GETLIST");
if(function == null)
throw new RuntimeException("BAPI_COMPANYCODE_GETLIST not found in SAP.");
try
{
function.execute(dest);
}
catch(AbapException e)
{
System.out.println(e.toString());
return;
}
JCoStructure returnStructure = function.getExportParameterList().getStructure("RETURN");
if (! (returnStructure.getString("TYPE").equals("")||returnStructure.getString("TYPE").equals("S")) )
{
throw new RuntimeException(returnStructure.getString("MESSAGE"));
}
JCoTable codes = function.getTableParameterList().getTable("COMPANYCODE_LIST");
for (int i = 0; i < codes.getNumRows(); i++)
{
codes.setRow(i);
System.out.println(codes.getString("COMP_CODE") + '\t' + codes.getString("COMP_NAME"));
}
//move the table cursor to first row
codes.firstRow();
for (int i = 0; i < codes.getNumRows(); i++, codes.nextRow())
{
function = dest.getRepository().getFunction("BAPI_COMPANYCODE_GETDETAIL");
if (function == null)
throw new RuntimeException("BAPI_COMPANYCODE_GETDETAIL not found in SAP.");
function.getImportParameterList().setValue("COMPANYCODEID", codes.getString("COMP_CODE"));
//We do not need the addresses, so set the corresponding parameter to inactive.
//Inactive parameters will be either not generated or at least converted.
function.getExportParameterList().setActive("COMPANYCODE_ADDRESS",false);
try
{
function.execute(dest);
}
catch (AbapException e)
{
System.out.println(e.toString());
return;
}
returnStructure = function.getExportParameterList().getStructure("RETURN");
if (! (returnStructure.getString("TYPE").equals("") ||
returnStructure.getString("TYPE").equals("S") ||
returnStructure.getString("TYPE").equals("W")) )
{
throw new RuntimeException(returnStructure.getString("MESSAGE"));
}
JCoStructure detail = function.getExportParameterList().getStructure("COMPANYCODE_DETAIL");
System.out.println(detail.getString("COMP_CODE") + '\t' +
detail.getString("COUNTRY") + '\t' +
detail.getString("CITY"));
}//for
}
}

Intercepting and modifying specific packets (IPv4/TCP)

I'm trying to intercept packets and be able to block them from incoming/outgoing, for a specific domain
In order to do that i made my (java) program adds the domain to the hosts file with a redirection to my own public ipv4 adress (this doesnt matter it just can't be the real IP and i must be able to intercept it, redirecting to my own IP makes sure nobody else in the world receives it). Secondly, i make the program listen to that signal and resend it on a different source port to the real server. (Checksum changes have been taken care of) Now the plan is to receive the response and do the exact same thing, but now by editting the source ip (my own public IP in this case) and the destination port
This should create a program where i'm a kind of middle men between a connection
But it doesnt work as expected, the moment im getting a response of the server (flags SYN/ACK), it's automatically sending them back a RST flag (IPv4/TCP) from the random chosen port by me which isnt the same as the port of the real client
I don't know if there are better ways to do this (there probably are) and how to prevent the problem I'm having, I couldn't really find similiar things to this on the internet. Any kind of help/hints would be appreciated
Keep in mind that I'm using jnetpscape at this moment and it would be nice to continue at what i'm doing right now
EDIT (code):
this is the "HConnection" class (not fully showed but all essential things):
public class HConnection {
private volatile int state = -1; // current state of the program
private volatile boolean HostFileEdited = false;
private volatile String domain = null;
private volatile boolean waitingConnection = false;
private volatile String ipOfDomain = null; // string of the server adress
private volatile byte[] ipofdomb; //4 bytes of the server adress
private volatile String myIpAdr = null; //my IP adress
private volatile byte[] myIpb; //my public IP in 4 bytes
private volatile byte[] port = null; //port of proxy
private volatile byte[] falseport = null; //port of client
private volatile ServerSocket server;
public HConnection() {
try {
server = new ServerSocket(0);
byte[] tempPortb = ByteBuffer.allocate(4).putInt(server.getLocalPort()).array();
System.out.println(server.getLocalPort());
port = new byte[]{tempPortb[2], tempPortb[3]};
(new Thread() {
public void run() {
try {
server.accept();
} catch (IOException e) {
System.out.println(e.getMessage());
}
}
}).start();
state = 0;
} catch (UnknownHostException e) {System.out.println("fail");} catch (IOException e) {System.out.println("fail");}
}
public String getPublicIP () {
try{
myIpAdr = new BufferedReader(new InputStreamReader(new URL("http://checkip.amazonaws.com/").openStream())).readLine();
System.out.println(myIpAdr);
InetAddress ip = InetAddress.getByName(myIpAdr);
myIpb = ip.getAddress();
return myIpAdr;
}
catch (Exception e){}
return null;
}
public void setUrl(String domain) {
this.domain = domain;
}
public int getState() {
return state;
}
public void prepare() {
try{
URL urlofsite = new URL("https://"+domain);
InetAddress address = InetAddress.getByName(urlofsite.getHost());
ipOfDomain = address.getHostAddress();
System.out.println(ipOfDomain);
ipofdomb = address.getAddress();
addToHostsFile(getPublicIP() + "\t" + domain);
state = 1;
}
catch(Exception e){}
}
public void abort() {
removeFromHostsFile(domain);
HostFileEdited = false;
state = -1;
try {
server.close();
} catch (IOException e) { }
waitingConnection = false;
}
public void awaitConnection() {
if (state == 1) {
waitingConnection = true;
System.out.println("stap1");
StringBuilder errbuf = new StringBuilder(); // For any error msgs
int snaplen = 64 * 1024; // Capture all packets, no truncation
int flags = Pcap.MODE_PROMISCUOUS; // capture all packets
int timeout = 0; // 10 seconds in millis
Pcap pcap = Pcap.openLive("wlp4s0", snaplen, flags, timeout, errbuf);
if (pcap == null) {
System.err.printf("Error while opening device for capture: "
+ errbuf.toString());
return;
}
PcapHeader hdr = new PcapHeader(JMemory.POINTER);
JBuffer buf = new JBuffer(JMemory.POINTER);
int id = JRegistry.mapDLTToId(pcap.datalink());
while (HostFileEdited && waitingConnection && state == 1 && pcap.nextEx(hdr, buf) == Pcap.NEXT_EX_OK) {
PcapPacket packet = new PcapPacket(hdr, buf);
try {
packet.scan(id);
TcpPacket pkt = new TcpPacket(packet);
if (pkt.isTcp()) {
if (pkt.destinationIPequals(myIpAdr) && pkt.getDestinationPort() == 443 && (falseport == null || Arrays.equals(pkt.getSourcePortb(), falseport))) {
if (falseport == null) {
falseport = pkt.getSourcePortb();
}
pkt.changeDestinationIP(ipofdomb);
pkt.changeSourcePort(port);
pkt.iPchecksumFix();
pkt.tcPchecksumFix();
ByteBuffer b = ByteBuffer.wrap(pkt.getPacketInBytes());
System.out.println("10");
System.out.println("OUT"+ (pcap.sendPacket(b)));
}
else if (pkt.sourceIPequals(ipOfDomain) && pkt.getSourcePort() == 443 && falseport != null && Arrays.equals(pkt.getDestinationPortb(),port) ) {
pkt.changeSourceIP(myIpb);
pkt.changeDestinationPort(falseport);
pkt.iPchecksumFix();
pkt.tcPchecksumFix();
ByteBuffer b = ByteBuffer.wrap(pkt.getPacketInBytes());
System.out.println("IN"+ pcap.sendPacket(b));
}
}
}
catch (Exception e) {}
}
System.out.println("stap2");
if (state == 1 && waitingConnection == true) state = 2;
waitingConnection = false;
}
}
}
The "awaitConnection()" method is were currently most things are happening. But this will only be the beginning of my program
HConnection is called from the main class (SWT Designer):
private Button btnNewButton_1;
private HConnection connectie;
private void btnConnect_clicked(SelectionEvent e) throws InterruptedException {
if (btnNewButton_1.getText().equals("Connect")) {
String Url = combo.getText();
connectie = new HConnection();
connectie.setUrl(Url);
connectie.prepare();
lblNewLabel_2.setText("Waiting -> client");
new Thread(new Runnable() {
public void run() {
connectie.awaitConnection();
Display.getDefault().asyncExec(new Runnable() {
public void run() {
if (connectie.getState() == 2) {
lblNewLabel_2.setText("Replacing URL");
}
else {
lblNewLabel_2.setText("Failed");
connectie.abort();
btnNewButton_1.setText("Connect");
}
}
});
if (connectie.getState() == 2) {
// go on with the rest of the program
}
}
}).start();
btnNewButton_1.setText("Abort");
}
else if(btnNewButton_1.getText().equals("Abort")) {
connectie.abort();
lblNewLabel_2.setText("Aborted");
btnNewButton_1.setText("Connect");
}
}

The following code accepts a connection, but doesn't maintain a reference to the resulting Socket instance. This Socket is eligible for garbage collection, and when that happens, it is automatically closed. A client sending data to that socket will then receive an RST.
public void run() {
try {
server.accept();
} catch (IOException e) {
System.out.println(e.getMessage());
}
}