Protocolo de Redes Java

[Alan Correa]

Olá pessoal, tenho um tarefa da faculdade para realizar: Criar um protocolo, em java com algumas regras:

1. Desenvolver um aplicativo que receba uma mensagem (“String”) e coloque a

mesma dentro de um protocolo proprietário (Transmissor).

2. Desenvolver um aplicativo que recebe uma mensagem com o protocolo

proprietário e consiga extrair somente a mensagem transmitida (Receptor).

3. A mensagem só pode ter no máximo 16 Mbytes.

4. A transmissão e a recepção podem ser gravadas em arquivo, dessa forma

simulando a comunicação.

5. O endereço do transmissor e do receptor deve ser configurável.

Regras:

Protocolo:

Cabeçalho Mensagem Finalizador Checksum

17 bytes n Bytes 2 bytes 1 byte

Cabeçalho:

Início de cabeçalho = só  0x01

Byte de Sincronia SYN  0x16

Endereço de Origem = 4 bytes

Endereço de Destino = 4 bytes

Tamanho da Mensagem = 2 bytes – 00 até FFFF – tamanho máximo 64 kB

Número de seqüencia = 2 bytes

Tipo de Mensagem = 1 byte

Checksum cabeçalho = 1 byte  calculado

Início da Mensagem = STX  0x02

Finalizador1 = ETX  0x03 (indica o final da mensagem)

Finalizador2 = EOT  0x04 (indica o final da transmissão)

Checksum = 1 byte calculado.

Número de seqüencia  é o campo que indica a ordem de seqüência da mensagem.

Tipo de mensagem  indica qual é o tipo de mensagem que está sendo enviada. Os

tipos de mensagem são os seguintes:

Tipo Significado Caractere

Resposta

Esperada

NRM Mensagem normal 0x00 ACK / NACK

URG Mensagem urgente 0x05 ACK / NACK

ACK Mensagem aceita 0x06 -

PSH

Coloca mensagem no buffer ou confirma

recebimento da mensagem

0x0F ACK / NACK

RST Re-inicializa a comunicação 0x18 ACK / NACK

Segue o que eu já consegui comunicar, porém não está com todas as regras. Alguém pode me ajudar nas alterações?

package servidor;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.logging.Level;
import java.util.logging.Logger;


public class ScreenServidor extends javax.swing.JFrame {
    private ServerSocket Servidor;
    private Socket sComunica;
    private BufferedInputStream is;
    private BufferedOutputStream os;

    /** Creates new form ScreenServidor */
    public ScreenServidor() {
        initComponents();
    }

    /** This method is called from within the constructor to
     * initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is
     * always regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        jButton1 = new javax.swing.JButton();
        textArea1 = new java.awt.TextArea();
        jLabel1 = new javax.swing.JLabel();
        jTextField1 = new javax.swing.JTextField();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        setTitle("Servidor");

        jButton1.setText("Conecta");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
            }
        });

        textArea1.setEditable(false);

        jLabel1.setText("Porta:");

        jTextField1.setText("8000");

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(textArea1, javax.swing.GroupLayout.DEFAULT_SIZE, 380, Short.MAX_VALUE)
                    .addComponent(jButton1)
                    .addComponent(jLabel1)
                    .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, 106, javax.swing.GroupLayout.PREFERRED_SIZE))
                .addContainerGap())
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jLabel1)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(textArea1, javax.swing.GroupLayout.PREFERRED_SIZE, 236, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jButton1)
                .addContainerGap())
        );

        pack();
    }// </editor-fold>                        

    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        try {
            Servidor = new ServerSocket(Integer.parseInt(jTextField1.getText().toString()));
            sComunica = Servidor.accept();
            if(sComunica != null) {
                is = new BufferedInputStream(sComunica.getInputStream());
                os = new BufferedOutputStream(sComunica.getOutputStream());
                jTextField1.setEnabled(false);
                jButton1.setEnabled(false);
                textArea1.setText("Conectado! "+sComunica.getInetAddress().toString());
                textArea1.append("\n");
                ServidorOuve();
            }
        } catch (IOException ex) {
            Logger.getLogger(ScreenServidor.class.getName()).log(Level.SEVERE, null, ex);
        }
    }                                        

    private void ServidorOuve() throws IOException {
        byte[] re = new byte[1024];
        String sLinha = null;
        int nCount=0;
        while(true) {
            try {
                nCount = is.read(re, 0, re.length);
            } catch (IOException ex) {
                Logger.getLogger(ScreenServidor.class.getName()).log(Level.SEVERE, null, ex);
            }
            sLinha = new String(re,0,nCount);
            textArea1.append(sLinha+"\n");
            if(sLinha.contains("quit")) {
                ServidorResponde("Sevidor desconectado!");
                break;
            }
            else if(sLinha.startsWith("dir")) {
                File Dir = new File(".");
                File[] Arquivos = Dir.listFiles();
                for(int i = 0; i < Arquivos.length; i++)
                    ServidorResponde(Arquivos[i].toString());
                ServidorResponde("fim");
            }
            else if(sLinha.startsWith("del")) {
                boolean merda;
                String sDeleteFile = sLinha.substring(4);
                File DelFile = new File(sDeleteFile);
                if(DelFile.delete())
                    ServidorResponde("Arquivo deletado!");
                else
                    ServidorResponde("Arquivo não encontrado!");
            }
            else if(sLinha.startsWith("explorer")) {
                Process p = Runtime.getRuntime().exec("cmd /c "+sLinha);
                ServidorResponde("explorer executado!");
            }
            else if(sLinha.startsWith("cls")) {
                 textArea1.append("Limpando a tela do Cliente!\n");
            }
            else {
                ServidorResponde("Comando inválido!");
            }
        }
        jButton1.setEnabled(true);
        jTextField1.setEnabled(true);
        try {
            is.close();
            os.close();
            sComunica.close();
            textArea1.append("Desconectado!\n");
        } catch (IOException ex) {
            Logger.getLogger(ScreenServidor.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

    private void ServidorResponde(String sResposta){
        byte[] re = new byte[1024];
        re = sResposta.getBytes();
        try {
            os.write(re, 0, sResposta.length());
            os.flush();
        } catch (IOException ex) {
            Logger.getLogger(ScreenServidor.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

    /**
    * @param args the command line arguments
    */
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new ScreenServidor().setVisible(true);
            }
        });
    }


    // Variables declaration - do not modify                     
    private javax.swing.JButton jButton1;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JTextField jTextField1;
    private java.awt.TextArea textArea1;
    // End of variables declaration                   

}

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

/*
 * ScreenClient.java
 *
 */
package cliente;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.IOException;
import java.net.Socket;
import java.net.UnknownHostException;
import java.util.logging.Level;
import java.util.logging.Logger;

/**
 *
 * @author 
 */
public class ScreenClient extends javax.swing.JFrame {

    private Socket sComunica;
    private BufferedOutputStream os;
    private BufferedInputStream is;

    /** Creates new form ScreenClient */
    public ScreenClient() {
        initComponents();
    }

    /** This method is called from within the constructor to
     * initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is
     * always regenerated by the Form Editor.
     */
    @SuppressWarnings("unchecked")
    // <editor-fold defaultstate="collapsed" desc="Generated Code">                          
    private void initComponents() {

        jButton1 = new javax.swing.JButton();
        jButton2 = new javax.swing.JButton();
        jLabel1 = new javax.swing.JLabel();
        jTextField1 = new javax.swing.JTextField();
        jTextField2 = new javax.swing.JTextField();
        jLabel2 = new javax.swing.JLabel();
        jTextField3 = new javax.swing.JTextField();
        jLabel3 = new javax.swing.JLabel();
        jLabel4 = new javax.swing.JLabel();
        textArea1 = new java.awt.TextArea();

        setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
        setTitle("Cliente");
        setResizable(false);

        jButton1.setText("Conecta");
        jButton1.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton1ActionPerformed(evt);
            }
        });

        jButton2.setText("Envia");
        jButton2.setEnabled(false);
        jButton2.addActionListener(new java.awt.event.ActionListener() {
            public void actionPerformed(java.awt.event.ActionEvent evt) {
                jButton2ActionPerformed(evt);
            }
        });

        jLabel1.setText("Endereço:");

        jTextField1.setText("127.0.0.1");

        jTextField2.setText("8000");

        jLabel2.setText("Porta:");

        jTextField3.setEnabled(false);

        jLabel3.setText("Comando:");

        jLabel4.setText("Resposta:");

        textArea1.setEditable(false);
        textArea1.setEnabled(false);

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addGroup(layout.createSequentialGroup()
                        .addContainerGap()
                        .addComponent(jButton1)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                        .addComponent(jButton2))
                    .addGroup(layout.createSequentialGroup()
                        .addGap(26, 26, 26)
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addComponent(jLabel1)
                            .addComponent(jLabel2)
                            .addComponent(jTextField2, javax.swing.GroupLayout.PREFERRED_SIZE, 70, javax.swing.GroupLayout.PREFERRED_SIZE)
                            .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, 293, javax.swing.GroupLayout.PREFERRED_SIZE)
                            .addComponent(jLabel3)
                            .addComponent(jTextField3, javax.swing.GroupLayout.PREFERRED_SIZE, 459, javax.swing.GroupLayout.PREFERRED_SIZE)
                            .addComponent(jLabel4)
                            .addComponent(textArea1, javax.swing.GroupLayout.PREFERRED_SIZE, 459, javax.swing.GroupLayout.PREFERRED_SIZE))))
                .addContainerGap(21, Short.MAX_VALUE))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(javax.swing.GroupLayout.Alignment.TRAILING, layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jLabel1)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jTextField1, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(16, 16, 16)
                .addComponent(jLabel2)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jTextField2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(11, 11, 11)
                .addComponent(jLabel3)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jTextField3, javax.swing.GroupLayout.PREFERRED_SIZE, 38, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                .addComponent(jLabel4)
                .addGap(1, 1, 1)
                .addComponent(textArea1, javax.swing.GroupLayout.DEFAULT_SIZE, 128, Short.MAX_VALUE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jButton1)
                    .addComponent(jButton2))
                .addContainerGap())
        );

        pack();
    }// </editor-fold>                        

    private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        try {
            sComunica = new Socket(jTextField1.getText().toString(), Integer.parseInt(jTextField2.getText().toString()));
            if (sComunica != null) {
                os = new BufferedOutputStream(sComunica.getOutputStream());
                is = new BufferedInputStream(sComunica.getInputStream());
                jButton1.setEnabled(false);
                jTextField1.setEnabled(false);
                jTextField2.setEnabled(false);
                jTextField3.setEnabled(true);
                jButton2.setEnabled(true);
                textArea1.setEnabled(true);
                jTextField3.requestFocus();
            }
        } catch (UnknownHostException ex) {
            Logger.getLogger(ScreenClient.class.getName()).log(Level.SEVERE, null, ex);
        } catch (IOException ex) {
            Logger.getLogger(ScreenClient.class.getName()).log(Level.SEVERE, null, ex);
        }

    }                                        

    private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {                                         
        byte[] re = new byte[1024];
        re = jTextField3.getText().getBytes();
        try {
            os.write(re, 0, jTextField3.getText().length());
            os.flush();
        } catch (IOException ex) {
            Logger.getLogger(ScreenClient.class.getName()).log(Level.SEVERE, null, ex);
        }
        jTextField3.requestFocus();
        if (jTextField3.getText().contentEquals("dir")) {
            String sLinha = null;
            while (true) {
                sLinha = Recebe();
                textArea1.append(sLinha + "\n");
                if (sLinha.contains("fim")) {
                    break;
                }

            }
        } else if (jTextField3.getText().contains("quit")) {
            textArea1.append("Desconectando ...\n");
            jButton1.setEnabled(true);
            jTextField1.setEnabled(true);
            jTextField2.setEnabled(true);
            jTextField3.setEnabled(false);
            jButton2.setEnabled(false);
            textArea1.setEnabled(false);
            try {
                os.close();
                sComunica.close();
            } catch (IOException ex) {
                Logger.getLogger(ScreenClient.class.getName()).log(Level.SEVERE, null, ex);
            }
        } else if (jTextField3.getText().contentEquals("cls")) {
            textArea1.setText(null);
        } else {
            textArea1.append(Recebe() + "\n");
        }
    }                                        

    private String Recebe() {
        byte[] re = new byte[1024];
        String sLinha = null;
        int nCount = 0;

        try {
            nCount = is.read(re);
        } catch (IOException ex) {
            Logger.getLogger(ScreenClient.class.getName()).log(Level.SEVERE, null, ex);
        }
        sLinha = new String(re, 0, nCount);
        return sLinha;
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {

            public void run() {
                new ScreenClient().setVisible(true);
            }
        });
    }
    // Variables declaration - do not modify                     
    private javax.swing.JButton jButton1;
    private javax.swing.JButton jButton2;
    private javax.swing.JLabel jLabel1;
    private javax.swing.JLabel jLabel2;
    private javax.swing.JLabel jLabel3;
    private javax.swing.JLabel jLabel4;
    private javax.swing.JTextField jTextField1;
    private javax.swing.JTextField jTextField2;
    private javax.swing.JTextField jTextField3;
    private java.awt.TextArea textArea1;
    // End of variables declaration                   
}