Proper sending and receiving via C# sockets?

Question

I\'m attempting to create a remote desktop server and client using C#. The server captures the screen and then sends it to the client via a socket. I\'m using the code below alt

Answer 1

You need to add application level protocol to your socket communications.

Add a header to all messages sent. The header contains the count of bytes that follow. It is simpler code and performs better to have a byte count than to kludge a termination sequence.

The client then does two sets of reads: 1) Read for the number of bytes that are known to be in any header.

2) After extracting the byte count from the header, loop reading until you get the indicated byte count.

A must-read article for all people who are writing socket communications: http://nitoprograms.blogspot.com/2009/04/message-framing.html From that article: Repeat this mantra three times: "TCP does not operate on packets of data. TCP operates on streams of data."

Answer 2

I have previously answered a similar question, and provided a fully working example that I think does exactly what you are trying to do. See: transferring a screenshot over a TCP connection

Answer 3

You must set a delimiter at the end of your image, some set of bytes that will sinalize the server that the image has ended. It's also known as end of file (EOF) or end of message. TCP won't split the image into logical packets for your app, so you must write your own control of information.

The logic would be similar to this: CLIENT

byte[] EndOfMessage = System.Text.Encoding.ASCII.GetBytes("image_end");
byte[] ImageBytes = GetImageBytes();
byte[] BytesToSend = new byte[EndOfMessage.Length + ImageBytes.Length];
Array.Copy(ImageBytes, 0, BytesToSend);
Array.Copy(EndOfMessage, 0, BytesToSend, ImageBytes.Length, EndOfMessage.Length);

SendToServer(BytesToSend);

SERVER

byte[] EndOfMessage = System.Text.Encoding.ASCII.GetBytes("image_end");
byte[] ReceivedBytes;

while(!IsEndOfMessage(ReceivedBytes, EndOfMessage ))
{
//continue reading from socket and adding to ReceivedBytes
}

ReceivedBytes = RemoveEndOfMessage(ReceivedBytes, EndOfMessage );
PrintImage(ReceivedBytes);

I'm at work right now and I can't provide a full running example, I'm sorry.

Regards

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Support methods:

private bool IsEndOfMessage(byte[] MessageToCheck, byte[] EndOfMessage)
{
    for(int i = 0; i++; i < EndOfMessage.Length)
    {
        if(MessageToCheck[MessageToCheck.Length - (EndOfMessage.Length + i)] != EndOfMessage[i])
            return false;
    }

    return true;
}

private byte[] RemoveEndOfMessage(byte[] MessageToClear, byte[] EndOfMessage)
{
    byte[] Return = new byte[MessageToClear.Length - EndOfMessage.Length];
    Array.Copy(MessageToClear, Return, Return.Length);

    return Return;
}

Again, I couldn't test them, so you may find some bugs.