Question

Issue

I have confirmed via a packet sniffer that all data coming from the client is being totally sent, and that the data being received by the server is complete as well, however there is a slight problem.

Here is a basic representation of relevant parts of the client thread within the server.

this.data_in = new DataInputStream(sock.getInputStream());
this.in = new InputStreamReader(this.data_in);

The server will read in authentication data using the BufferedReader, and once authentication is complete it will read data from the socket, like so. The variable ‘fos’ is a FileOutputStream that the DataInputStream data is being written to.

int read = 0;
byte[] buffer = new byte[8192];
while((read = data_in.read(buffer)) != -1) {
    fos.write(buffer, 0, read);
    bytes_received += read;
}

This all seems correct in concept, however, in practice the first 1450 bytes of the file read in are missing. I have tried using a new DataInputStream(sock.getInputStream()) in case the position in the stream was weird but still no luck. Thanks for any help!

Update 1

So I could use BufferedReader functionality I made a method to read in string lines as I was using them before. See below code.

int input;
boolean run = true;
while((input = in.read()) != -1 && run) {
    run = true;
    char[] chars = Character.toChars(input);
    for(char c : chars) {
        if(c == '\n') {
            run = false;
            break;
        } else if(c != '\r') {
            sb.append(c);
        }
    }
}

As great of a solution it seemed, there is still 1450 bytes of information missing. Maybe I’m going in the wrong direction here?

Answer 1

To me it looks like the BufferedReader is the problem – according to http://ulibgcj.sourceforge.net/javadoc/java/io/BufferedReader.html is has default buffer size of 8192… whatever this default buffer size is in your case, the BufferedReader will advance the data_in in steps of that default buffer size… so even if you don’t consume them data_in is usually on a position beyond the last bytes you consumed during authentication.