TFTP Client Rev RFC 1350

Client.java

// Client

import java.net.*;
import java.io.*;
import java.util.*;
import java.nio.charset.*;
import java.time.LocalTime;

public class Client
{
    public static int serverPort = 69;
    public static int blockNumber = 0;
    public static String serverAddress;
    public static int timeouts = 0;
    public static int missedPackets = 0;
    public static int filePosition = 0;
    public static int clientPort = 0;
    public static FileInputStream fileStream;
    public static final int TIMEOUTS_MAX = 6;
    public static final int MISSED_PACKET_MAX = 6;
    public static final int BUFFER_SIZE = 516;
    public static final int TIMEOUT_INTERVAL = 2000;
    
    public static final boolean DEBUG = false;
    
    public static void main(String args[])
    {
        if(args.length != 3 && args.length != 4)
        {
            System.out.println("Improper argument length. Correct options are:\n\t <host> <PUT|GET> <file> [binary]");
            return;
        }
            
        serverAddress = args[0];
        String operation = args[1].toUpperCase();
        String fileName = args[2];
        String mode = "netascii";
        if(!"PUT".equals(operation) && !"GET".equals(operation))
        {
            System.out.println(String.format("Could not handle \'operation\' %s\nAccepted operations are:\n\tPUT\tGET\n",operation));
            return;
        }        
        File file = new File(fileName);
        if(!file.exists() || file.isDirectory()) 
        { 
            System.out.println(String.format("Could not handle request\n\t%s\ndoes not exist", fileName));
            return; 
        }
        long fileSize = file.length();
        if(fileSize > 65536 * 512)
        {
            System.out.println("\nFile over maximum. Consider packaging file into 32Mb archives.");
            //return;
        }
        
        if(args.length == 4)
            if("binary".equals(args[3]))        
            {
                mode = "octet";
                try{fileStream = new FileInputStream(file);}
                catch(Exception e){}
            }
        
        byte OPCode;
        if("GET".equals(operation)) 
            OPCode = 0x1;
        else
        {
            OPCode = 0x2;
        }
        
        // Communications
        
        byte[] receiveData = new byte[Client.BUFFER_SIZE];
        try
        {
            ByteArrayOutputStream sendStream = new ByteArrayOutputStream(Client.BUFFER_SIZE);
            ByteArrayOutputStream receiveStream = new ByteArrayOutputStream(Client.BUFFER_SIZE);
            int replyPort = 0;
            int randomPort = new Random().nextInt(64000) + 1024;
            Client.clientPort = randomPort;
            
            sendStream.write(0x0);
            sendStream.write(OPCode);
            sendStream.write(fileName.getBytes("US-ASCII"));
            sendStream.write(0x0);
            sendStream.write(mode.getBytes("US-ASCII"));
            sendStream.write(0x0);
            
            
            DatagramSocket client = new DatagramSocket(randomPort);    
            client.setSoTimeout(Client.TIMEOUT_INTERVAL);            
            
            DatagramPacket receivedPacket = new DatagramPacket(receiveData, receiveData.length);                   
            
            while(true)
            {
                try
                {
                    send(sendStream.toByteArray(), client, Client.serverPort);            
                    client.receive(receivedPacket);
                    replyPort = receivedPacket.getPort();
                    receiveData = receivedPacket.getData();                    
                    break;
                }
                catch(SocketTimeoutException e)
                {
                    Client.timeouts++;
                    if(Client.timeouts>Client.TIMEOUTS_MAX)
                    {
                        System.out.println("Maximum number of attempts reached. No ACK received");
                        return;
                    }
                    System.out.println("\nTimed out, retrying...\nNumber of attemps: " + Client.timeouts); 
                    send(sendStream.toByteArray(), client, replyPort);                    
                }
            }
            
            //debug("'" + new String(receiveData, "US-ASCII") + "'");
            if(receiveData[1] == 5)
            {
                System.out.println("Error:\n\t" + new String(Arrays.copyOfRange(receiveData, 4, receiveData.length), StandardCharsets.US_ASCII));
                return;
            }
            if(0x2 == OPCode && receiveData[1] == 4)
            {
                // State information
                
                debug("Acknowledged write request");
                int blockOne = 1;
                int blockTwo = 0;
                int sentData = 0;
                byte[] lastSentPacket = sendStream.toByteArray();
                byte[] lastReceivedPacket = receiveData;                
                //Date date = new Date();
                long start = new Date().getTime();
                int dataInterval = 0;
                double rate = 0;
                while(sentData < fileSize)
                {                       
                    Client.timeouts = 0;
                    missedPackets = 0;
                    
                    debug("Creating packet");
                    sendStream.reset();
                    sendStream.write(0x0);
                    sendStream.write(0x3);
                    sendStream.write((byte) blockTwo);
                    sendStream.write((byte) blockOne);
                    read(sendStream, mode);
                    debug(""+sendStream.size());
                    sentData += sendStream.size() - 4; // Don't do buffer size because of last f          
                    dataInterval += sendStream.size() - 4;
                    if(blockOne % 50 == 0)
                    {
                        start = new Date().getTime();
                        dataInterval = 0;
                    }
                    if(blockOne % 50 == 49)
                        rate = (double) dataInterval / (new Date().getTime() - start);
                    
                    String status = String.format("\rStatus:\t%.2f%%", (double) sentData/fileSize*100);
                    status += String.format("\t\tRate: \t%.0fkbps", rate);
                    System.out.print(status);    
                    
                    debug("Sending data now");
                    send(sendStream.toByteArray(), client, replyPort);
                    lastSentPacket = sendStream.toByteArray();
                    
                    while(true)
                    {
                        try
                        {
                            client.receive(receivedPacket);
                            receiveData = receivedPacket.getData();
                            lastReceivedPacket = receiveData;
                            
                            // TFTP resets at 128 to block 63 ???
                            //if(block==128 && receiveData[3] == 63)
                            //    block = 62;
                            
                            replyPort = receivedPacket.getPort();
                            break;
                        }
                        catch(SocketTimeoutException e)
                        {
                            Client.timeouts++;
                            if(Client.timeouts>Client.TIMEOUTS_MAX)
                            {
                                System.out.println("Maximum number of attempts reached. Ending program.");
                                        return;
                            }
                            System.out.println("\nTimed out, retrying...\nNumber of attemps: " + Client.timeouts); 
                            send(lastSentPacket, client, replyPort);                            
                            
                        }
                    }
                    
                    if(receiveData[3] != blockOne || receiveData[2] != blockTwo)
                    {
                        if(receiveData[1] == 5)
                        {
                            System.out.println("Error:\n\t" + new String(Arrays.copyOfRange(receiveData, 4, receiveData.length), StandardCharsets.US_ASCII));
                                return;
                        }
                        
                        if(receiveData[3] == blockOne - 1 && receiveData[2] == blockTwo)
                        {
                            while(true)
                            {
                                try
                                {
                                    Client.missedPackets++;
                                    if(Client.missedPackets > Client.MISSED_PACKET_MAX)
                                    {
                                        System.out.println("Maximum number of missed packets reached. Ending program.");
                                                        return;
                                    }
                                    
                                    System.out.println("\nMissed packet...\n"+ Client.missedPackets + " missed packets");
                                    send(lastSentPacket, client, replyPort);
                                    
                                    client.receive(receivedPacket);
                                    receiveData = receivedPacket.getData();                        
                                    lastReceivedPacket = receiveData;
                                    
                                    /*
                                    if(block==128 && receiveData[3] == 63)
                                        block = 62;
                                    */
                                    
                                    replyPort = receivedPacket.getPort();
                                    break;
                                }
                                catch(SocketTimeoutException e)
                                {
                                    Client.timeouts++;
                                    if(Client.timeouts>Client.TIMEOUTS_MAX)
                                    {
                                        System.out.println("Maximum number of attempts reached. Ending program.");
                                                        return;
                                    }
                                    System.out.println("Timed out, retrying...\nNumber of attemps: " + Client.timeouts);                                   
                                }
                            }
                        }                        
                    }
                    //System.out.println("\nBlock "+block+"\n");
                    blockOne++;
                    if((byte) blockOne == 0 && (blockOne > 0 || blockTwo>0)) 
                        blockTwo++;
                    if((byte) blockTwo == 0xff && blockOne == 0xff && fileStream.available() > 0)
                    {
                        System.out.println("\nMaximum transfer size reached. Consider packaging file into 32Mb archives.");
                        return;
                    }
                }
                
                System.out.println("\nFile transfer complete.");
                
            }                
        }
        catch(Exception e)
        {
            System.out.println(e.toString());
        }
        return;
    }
    
    public static void read(ByteArrayOutputStream sendStream, String mode)
    {
        switch(mode)
        {
            case "octet":            
                try
                {
                    int b = 0;
                    while(sendStream.size() < Client.BUFFER_SIZE)
                    {
                        if((b = fileStream.read()) > -1)
                        {
                            sendStream.write(b);
                        }
                        else
                        {
                            break;
                        }
                    }
                }
                catch(Exception e)
                {
                    debug(e.toString());
                }
                debug("Last bit read");
                break;
                
            case "netascii":
                debug("Netascii mode");
                break;
                
            default:
                System.out.println("Invalid mode specified");
                return;
                
        }
        
    }
    
    public static void send(byte[] response, DatagramSocket client, int port)
    {
        try
        {   
            InetAddress IP = InetAddress.getByName(Client.serverAddress);
            DatagramPacket packetToSend = new DatagramPacket(
                        response,
                        response.length,
                        IP,
                        port
                        );
            client.send(packetToSend);
        }
        catch(Exception e)
        {
            System.out.println(e.toString());
        }
    }
    
    public static void debug(String output)
    {   
        if(Client.DEBUG)
            System.out.println(output);
    }
    
    public static void debug(byte[] array)
    {
        if(Client.DEBUG)
        {
            String debug = "";
            for(int x = 0; x < array.length; x++)
            {
                debug += " " + array[x];
            }
            
            System.out.println(debug);
        }
    }
}