CODEWITHSUNDEEP
c#tcp
plkana
plkana

Reputation: 51

TCP client to server corrupts data

This is very weird.

When I send data to a TCP server, with a TCP client. It corrupts the data, for some extremely odd, and quite annoying reason.

Here is the server code:

TcpListener lis = new TcpListener(IPAddress.Any, 9380); // it needs to be 9380, crucial
lis.Start();
Socket sk = lis.AcceptSocket();
byte[] pd = new byte[sk.ReceiveBufferSize];
sk.Receive(pd);

// cd is the current directory, filename is the file, ex picture.png, 
// that was previously sent to the server with UDP.
File.WriteAllBytes(Path.Combine(cd, filename), pd);

Here is the client code:

// disregard "filename" var, it was previously assigned in earlier code
byte[] p = File.ReadAllBytes(filename) 
TcpClient client = new TcpClient();
client.Connect(IPAddress.Parse(getIP()), 9380);
Stream st = client.GetStream();
st.Write(p, 0, p.Length);

What happens is data loss. Extreme, sometimes I would upload a 5KB file, but when the server receives and writes the file I send it, it would turn out crazy like 2 bytes. Or it would be 8KB instead! Applications send through this won't even run, pictures show errors, ect.

I would like to note, however, with this, client -> server fails, on the other hand, server -> client works. Strange.

Btw, in case you are interested this is for sending files... Also, using .NET 4.5. Also, my network is extremely reliable.

Upvotes: 0

Views: 91

Answers (1)

Mark
Mark

Reputation: 1554

Hi I think you have some misconceptions about TCP. I can see you are setting up a server with a receive buffer of x bytes. Firstly have you checked to see how many bytes that is? I suspect it is very small something like 1024 or something. When writing data over TCP the data is split into frames. Each time you receive you will get some of the data sent and it will tell you how much of the data has been received . As I can see from your use case you do not know the size of the data to receive so you will have to build up a protocol between your client and server to communicate this. The simplest of such would be to write a 4 byte integer specifying the size of the data to be received. The communication would go like this.

Client:

  1. Write 4 bytes (file size)
  2. Write Data bytes

Server:

  1. Read 4 bytes (file size)
  2. While we have yet to receive file size read the stream and push bytes into memory/file stream

Upvotes: 1

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