C#•4mo ago

✅ Mysterious byte problem

https://github.com/MellowZippy1/Networking I am working on a school project, I need to make a UDP-based FTP server, it should send a file using a slow-start approach, this has not been implemented yet. I do have a quite unique problem which is that even though I should be sending the same amount of bytes to the client (1024 bytes plus a JSON overhead) it keeps sending different amounts of overhead as shown in the picture below. It is sending all the data but I am wondering why the amount of bytes keeps changing? Is this an issue or just something that I should deal with?

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GitHub - MellowZippy1/Networking: Networking assignments met Naud

Networking assignments met Naud . Contribute to MellowZippy1/Networking development by creating an account on GitHub.

28 Replies

mellowzippy•4mo ago

Unsure what difficulty to tag this problem at. I just pushed the new version, if there's any bugs please attempt to clone again

Angius•4mo ago

Did you try debugging to see what gets sent?

mellowzippy•4mo ago

Yeah It sends an array of 1024 bytes, a MessageType enum which is Data and then some json overhead. I am unsure why this would keep changing? Its 1024 bytes, the same MessageType and it should be the same json overhead, right?

Angius•4mo ago

Is the content of the JSON the same each time?

mellowzippy•4mo ago

No, it would be different parts of the hamlet. But it would still be 1024 bytes Same amount of bytes, different bytes.

Angius•4mo ago

Then the length will differ as well

mellowzippy•4mo ago

How so?

Angius•4mo ago

{"name":"bob"} is shorter than {"name":"phranephrates"}

mellowzippy•4mo ago

no think of it like this:

{"content": "abc"}
{"content": "cba"}

{"content": "abc"}
{"content": "cba"}

{"content": "abc"}
{"content": "def"}

{"content": "abc"}
{"content": "def"}

It would be the same amount of bytes, correct?

Angius•4mo ago

Yeah

mellowzippy•4mo ago

So why does it send a different amount of bytes

Angius•4mo ago

Place a breakpoint at where the data gets serialized, and double-check that it actually always gets serialized to a string of the same length

mellowzippy•4mo ago

A string gets put into a byte[1024]

Angius•4mo ago

a string gets put into a byte[] Of whatever is the length required

mellowzippy•4mo ago

no the length is always 1024

Angius•4mo ago

            string serializedMessage = JsonSerializer.Serialize(message);
            byte[] data = Encoding.ASCII.GetBytes(serializedMessage);

            string serializedMessage = JsonSerializer.Serialize(message);
            byte[] data = Encoding.ASCII.GetBytes(serializedMessage);

yes

mellowzippy•4mo ago

so hamlet (a big file) gets split into multiple packets of 1024 byes.

Angius•4mo ago

I don't see you setting 1024 anywhere here

mellowzippy•4mo ago

private Dictionary<int, (bool, byte[])>? InitializePackets()
    {
        Dictionary<int, (bool, byte[])>? packets = new();
        try
        {
            string text = File.ReadAllText("hamlet.txt");
            byte[] tempbuffer = Encoding.ASCII.GetBytes(text);
            int amountOfPackets = (int)Math.Ceiling((double)tempbuffer.Length / (double)ChunkSize);

            for (int i = 0; i < amountOfPackets; i++)
            {
                int startIndex = i * ChunkSize;
                int length = Math.Min(ChunkSize, tempbuffer.Length - startIndex);
                byte[] chunk = new byte[length];
                Buffer.BlockCopy(tempbuffer, startIndex, chunk, 0, length);
                packets[i] = (i == amountOfPackets - 1, chunk); // Mark last packet
            }

            return packets;
        }
        catch (Exception e)
        {
            Console.WriteLine(e.Message);
            HandleErrors(e);
        }

        return null!;
    }

private Dictionary<int, (bool, byte[])>? InitializePackets()
    {
        Dictionary<int, (bool, byte[])>? packets = new();
        try
        {
            string text = File.ReadAllText("hamlet.txt");
            byte[] tempbuffer = Encoding.ASCII.GetBytes(text);
            int amountOfPackets = (int)Math.Ceiling((double)tempbuffer.Length / (double)ChunkSize);

            for (int i = 0; i < amountOfPackets; i++)
            {
                int startIndex = i * ChunkSize;
                int length = Math.Min(ChunkSize, tempbuffer.Length - startIndex);
                byte[] chunk = new byte[length];
                Buffer.BlockCopy(tempbuffer, startIndex, chunk, 0, length);
                packets[i] = (i == amountOfPackets - 1, chunk); // Mark last packet
            }

            return packets;
        }
        catch (Exception e)
        {
            Console.WriteLine(e.Message);
            HandleErrors(e);
        }

        return null!;
    }

Angius•4mo ago

Ah, I was looking at the client

mellowzippy•4mo ago

Is okay

Angius•4mo ago

Huh At which point does the size become not-1024?

! ! Paradise•4mo ago

wow cool

mellowzippy•4mo ago

In theory, the content of each packet should be 1024 bytes (plus overhead, which should be the same). In practice, the total amount of bytes keeps changing everytime it gets sent.

Angius•4mo ago

Yeah, but where? How deep did you try placing the breakpoints? I'd step through the code from the moment you split the file text, and see where does the length change

mellowzippy•4mo ago

We figured it out, its because we encoded the chunk of hamlet text twice. We encode it, then convert it to json, encode it again and send it How do I close a ticket?

Angius•4mo ago

$close

MODiX•4mo ago

Use the /close command to mark a forum thread as answered

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✅ Mysterious byte problem