How to transfer all types of files such as exe,html,gif,jpg using TCP?

Question

Respected Sir / Madam,
I am doing my project in Network Security using Java. The main aim of my project is to transfer the files between the client and server in a secured way. I have used MD5 algorithm to authenticate the person who are in the client machine. If the user is an authorized user then the user requested file should be transferred from server to client after encrypting the contents using DES algorithm. B4 encrypting the contents I have just transferred the file for checking. But I could transfer only .java and .txt files. From the forum I got the info that if we handle the data in byte format then we can transfer any kind of files. So I tried bu t I couldn't get the entire contents. If I transfer the file then transferred contents is in the form of [B061234 like this only. How can I rectify this problem. I will be grateful if anyone of you help me.  Thank you very much. Here are my codings.
Server Side Codings
     try
                     FileInputStream fis = new FileInputStream(new File(fname));
                     int nos = fis.available();
                     fdata = new byte[nos];
System.out.println("No.of bytes = " + nos);
fl=1;
System.out.println("FDATA = " + fdata);
int ch,i=0;
while((ch =fis.read())!=-1)
fdata[j++]=(byte)ch;
System.out.println("Ch "+ i++ + " = " + ch);
System.out.println("J = " + j);
sendMsgs(s,fdata); // s is the Socket of the client
public void sendMsgs(Socket s,byte b[])
PrintStream p;
try
p = new PrintStream(s.getOutputStream());
System.out.println("Sending Msg = " + b);
p.println(b);
catch(Exception e)
System.out.println("Sending Error : " + e);
Client Side Codings
public void start()
try
s = new Socket(InetAddress.getLocalHost().getHostName(),2500);
dis = new DataInputStream(s.getInputStream());
ByteArrayInputStream bis = new ByteArrayInputStream(s.getInputStream());
ps = new PrintStream(s.getOutputStream());
t = new Thread(this);
t.start();
catch(Exception e) {}
public void run()
String msg="",c="";
int f=0;
byte m[] = new byte[1000];
try
while(true)
// msg = dis.readLine();
m=bis.readLine().getBytes();
FileOutputStream fos = new FileOutputStream(new File("c:\\" + fnam),true);
fos.write(m);
fos.flush();
fos.close();
catch(Exception e){}
f=1;
}

Answer 1

int nos = fis.available();That method shouldn't be used to determine the file size. Use File.length().
public void sendMsgs(Socket s,byte b[])
PrintStream p;Bad. Don't use PrintStreams or PrintWriters in association with sockets, as they swallow exceptions.
try
p = new PrintStream(s.getOutputStream());
System.out.println("Sending Msg = " + b);
p.println(b);That writes b.toString() to the socket followed by a newline. That's not what you want to do. Just write the bytes directly to the socket output stream. Then close the socket, or the output stream if you use one.
dis = new
DataInputStream(s.getInputStream());Good, but unnecessary.
ByteArrayInputStream bis = new
ByteArrayInputStream(s.getInputStream());Bad, and it isn't used anyway.
// msg = dis.readLine();
m=bis.readLine().getBytes();Worse. Just read the bytes directly with the DataInputStream and write them to the FileOutputStream. Don't use PrintWriters or Object.toString() anywhere where you expect to recover the original data.
The issue here is that you're not sending what you think you're sending, and you're not reading it correctly. String is not a container for binary data. Just send and receive the binary data - the bytes - directly.
And you're reinventing the wheel. What's wrong with SSL?