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C# Socket Receive messes up data

I am trying to create a client/server application which communicates through Sockets. But when I receive data it randomly messed up and does not always (sometimes) show the correct data. The code I use to receive data:
private static void ReceiveCallback(IAsyncResult AR)
{
try
{
Socket socket = (Socket)AR.AsyncState;
if (SocketConnected(socket))
{
int received = socket.EndReceive(AR);
byte[] dataBuf = new byte[received];
Array.Copy(_buffer, dataBuf, received);
string text = Encoding.ASCII.GetString(dataBuf);
if (!text.Contains("GET") && !text.Contains("HTTP") && text != null)
{
Console.WriteLine(DateTime.Now.ToString("h:mm:ss tt") + ":" + text);
}
socket.BeginReceive(_buffer, 0, _buffer.Length, SocketFlags.None, new AsyncCallback(ReceiveCallback), socket);
}
}
catch
{
}
}
can someone explain me why this happends? Thanks in advance!
Also, I have tried to check untill it finds a character (which is on the end of every response '-' but that did not work). Unfortunatley this was the result:

I assume your socket is a TCP socket, since you're dealing with something like HTTP.
TCP deals with streams, not messages. So when you do your read, at most _buffer.Length bytes are read from the stream. This means that you can easily read just a part of the response - or rather, the response will be split between multiple callbacks. When you read enough by chance, everything works as expected. This is especially true when testing on localhost, because Windows treats localhost TCP very differently from the non-localhost case. But when it so happens that you don't read enough, text will not contain the whole response - and your data is broken.
Additionally, when received is zero, it means the other side has closed the stream and you should stop doing BeginReceive.

You have to loop on the socket receive until you get your entire message.
This also means that you must have an application level protocol. What defines a message?
A termination character? Then loop on the read until you get that character.
A count of characters? Then loop on the read until you get that many characters.
Is the length of the message at the front of the message? Then loop until you get enough bytes to get the length, then loop until you get the entire message.

Your socket code looks fine to me. Characters encoding format in the .Net world is "Unicode", you should convert the bytes you receive to Unicode instead of ASCII :
string text = Encoding.Unicode.GetString(dataBuf);

issue with getting TcpClient server response as string

so long story short, i am trying to develop an application which requires having Tcp Connection to a server. having no previous experiance in this field i ended up with having none of my functions working. so i decided to make a simple console app just to check my commands and their responses. the part about setting up the connections went well, so does the part about wrting into network stream(i think) but i hit a wall when trying to display server respons:
each time my porgram reaches the line where it has to Encode server respons and WriteLine, my console application goes all black and all texts goes away. can you tell what's wrong with the code i am using?everything up until the part where console trys to display response goes well, i checked. i want to have server's respones as normal strings(if possible i guess...)
static void ServerTalk(TcpClient tcpClient,NetworkStream networkStream, StreamWriter streamWriter, StreamReader streamReader)
{
//Messaging methods:
Console.WriteLine("Client: ");
string message = Console.ReadLine();
streamWriter.WriteLine(message);
streamWriter.Flush();
//Response methode:
byte[] data = new byte[tcpClient.ReceiveBufferSize];
int ret = networkStream.Read(data, 0, data.Length);
string respond = Encoding.ASCII.GetString(data).TrimEnd();
Console.WriteLine("Server: ");
Console.WriteLine(respond);
ServerTalk(tcpClient, networkStream, streamWriter, streamReader);
}

you need to process only ret bytes, you are translating all bytes in the array.
copy to a new array that is 'ret' long and then decode.
var retarr = new byte[ret];
Array.Copy(data,retarr,ret);
string respond = Encoding.ASCII.GetString(retarr);
More importantly note that this method of tcp communication is not going to work. You are assuming that when you send x bytes in one block you will receive x bytes in one block, this is not so, you can send 1 100 byte message and receive 100 1 byte messages
This means that you task is much more complex. YOu need to devise a way of sending self describing data - so that you know its completely received. classically you send a length followed by the data. You then keep looping in the receive code till you have received that many bytes

sending a large amount of data throught TCP socket

This is my first question posted on this forum, and I'm a beginner in c# world , so this is kind of exciting for me, but I'm facing some issues with sending a large amount of data through sockets so this is more details about my problem:
I'm sending a binary image of 5 Mo through a TCP socket, at the receiving part I'm saving the result(data received ) and getting only 1.5 Mo ==> data has been lost (I compared the original and the resulting file and it showed me the missed parts)
this is the code I use:
private void senduimage_Click(object sender, EventArgs e)
{
if (!user.clientSocket_NewSocket.Connected)
{
Socket clientSocket_NewSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
user.clientSocket_NewSocket = clientSocket_NewSocket;
System.IAsyncResult _NewSocket = user.clientSocket_NewSocket.BeginConnect(ip_address, NewSocket.Transceiver_TCP_Port, null, null);
bool successNewSocket = _NewSocket.AsyncWaitHandle.WaitOne(2000, true);
}
byte[] outStream = System.Text.Encoding.ASCII.GetBytes(Uimage_Data);
user.clientSocket_NewSocket.Send(outStream);
}
In forums they say to divide data into chunks, is this a solution, if so how can I do this, I've tried but it didn't work!

There are lots of different solutions but chunking is usually a good solution, you can either do this blindly where you keep filling your temporary buffer and then putting it into some stateful buffer until you hit some arbitrary token or the buffer is not completely full, or you can adhere to some sort of contract per tcp message (a message being the overall data to recieve).
If you were to look at doing some sort of contract then do something like the first N bytes of a message is the descriptor, which you could make as big or as small as you want, but your temp buffer will ONLY read this size up front from the stream.
A typical header could be something like:
public struct StreamHeader // 5 bytes
{
public byte MessageType {get;set;} // 1 byte
public int MessageSize {get;set;} // 4 bytes
}
So you would read that in then if its small enough allocate the full message size to the temp buffer and read it all in, or if you deem it too big chunk it into sections and keep reading until the total bytes you have received match the MessageSize portion of your header structure.

Probably you haven't read the documentation on socket usage in C#. (http://msdn.microsoft.com/en-us/library/ms145160.aspx)
The internal buffer can not store all the data you provided to send methode. A possible solution to your problem can be is like you said to divide your data into chunks.
int totalBytesToSend = outstream.length; int bytesSend = 0;
while(bytesSend < totalBytesToSend )
bytesSend+= user.clientSocket_NewSocket.Send(outStream, bytesSend, totalBytesToSend - bytesSend,...);

I suspect that one of your problems is that you are not calling EndConnect. From the MSDN documentation:
The asynchronous BeginConnect operation must be completed by calling the EndConnect method.
Also, the wait:-
bool successNewSocket = _NewSocket.AsyncWaitHandle.WaitOne(2000, true);
is probably always false as there is nothing setting the event to the signaled state. Usually, you would specify a callback function to the BeginConnect function and in the callback you'd call EndConnect and set the state of the event to signaled. See the example code on this MSDN page.
UPDATE
I think I see another problem:-
byte[] outStream = System.Text.Encoding.ASCII.GetBytes(Uimage_Data);
I don't know what type Uimage_Data but I really don't think you want to convert it to ASCII. A zero in the data may signal an end of data byte (or maybe a 26 or someother ASCII code). The point is, the encoding process is likely to be changing the data.
Can you provide the type for the Uimage_Data object?

Most likely the problem is that you are closing the client-side socket before all the data has been transmitted to the server, and it is therefore getting discarded.
By default when you close a socket, all untransmitted data (sitting in the operating system buffers) is discarded. There are a few solutions:
[1] Set SO_LINGER (see http://developerweb.net/viewtopic.php?id=2982)
[2] Get the server to send an acknowledgement to the client, and don't close the client-side socket until you receive it.
[3] Wait until the output buffer is empty on the client side before closing the socket (test using getsocketopt SO_SND_BUF - I'm not sure of the syntax on c#).
Also you really should be testing the return value of Send(). Although in theory it should block until it sends all the data, I would want to actually verify that and at least print an error message if there is a mismatch.

Socket Client answer

I'm creating a client/server socket app. And I'm not being able to solve this problem, probably due to lack of knowledge on the matter.
The client must send an answer in order to proceed communication:
while(comunicate)
{
if (chkCorrectAnswer.Checked)
answer = encoder.GetBytes('\x02' + "82SP|" + '\x03');
else
answer = encoder.GetBytes("bla");
ServerStream.Write(answer, 0, answer.Length);
//or ??
//tcp.Client.Send(answer);
}
And the server recieves it:
while(comunicate)
{
var validanswer= encoder.GetBytes("myvalidanswer");
answer = new byte[validanswer.Length];
stream.Read(answer, 0, validanswer.Length);
//or ??
//tcp.Client.Receive(answer);
if (answer.SequenceEqual(validanswer))
// continue communication
}
Each code is in different app, looped "comunication thread".
The answer seems being sent correctly but the server doesn't seem to be recieveing it porperly. Sometimes it recieves blablab or lablabl and variations with 7 chars. I thoung the recieving would fill the buffer only with the incoming data and somehow it is filling the buffer with repeated data.
Two questions here:
What should I use, stream.write/read or client.send/recieve?
How to ensure this answer verification?

0x02 and 0x03 is called start of text (STX) and end of text (ETX) and are separators used to identify where your messages starts and ends. There is really no need to use both, it was a common practice when doing serial communication.
You need to continue building a message until ETX is received.
something like (easiest solution but not very efficient if you have lots of clients)
string buffer = "";
var readBuffer = new byte[1];
int readBytes = 0;
while ((readBytes = stream.Read(readBuffer, 0, 1)) == 1 && readBuffer[0] != 3)
{
buffer += readBuffer[0];
}
you can of course read larger chunks. But then you need to check if more than one message was arrived and process the buffer accordingly. That's how I would do it though.

I thoung the recieving would fill the buffer only with the incoming data and somehow it is filling the buffer with repeated data.
Well, you are repeatedly sending the data in a loop, so this is to be expected.
If you want to read only a certain number of bytes off the stream you need to also send the size of the logical packet ahead of it so that the receiving end can first read the size (say as a fixed int value) and then the actual response.

When you do the read you'll get everything you wrote including amything you've written previously.
Implement a length header or some kind of seperator so you know what's what --
length + message
or
message + seperator
Then parse it when you do the read.

C# void ReceiveData(IAsyncResult iar)

i would like some help with the following. this is to do with Asynchronous sockets.
from the sender:
string stringData = "Welcome to my server server server";
byte[] message1 = Encoding.ASCII.GetBytes(stringData);
//MessageBox.Show(message1.Length.ToString());
client.BeginSend(message1, 0, message1.Length, SocketFlags.None, new AsyncCallback(SendData), client);
here as can be seen, the message.length can be found.
--
on the client:
Socket remote = (Socket)iar.AsyncState;
int recv = remote.EndReceive(iar);
string stringData = Encoding.ASCII.GetString(data, 0, recv);
my question is is there a way to access the actual length of the sent data and based on that call recieve data until the complete message is recieved?

No - TCP/IP is a stream protocol. Just because you've sent the data with one call doesn't mean it will be sent as one packet, or that it won't be merged with other packets. In other words, sending "X" then "Y" is equivalent to sending "XY" - they may well be transmitted with the exact same packets, indistinguishable to the other end.
If you want the idea of an individual "message" in a stream, you should prefix the data with a few bytes explicitly stating its length. (An alternative is to use a delimiter, but I far prefer using a length prefix - it makes it easier to know how much data you've still got to receive, you don't need to worry about starting to consume the next message, and you don't have to worry about escaping the delimiter in some form.)

Only if something is transmitted to communicate the length - either pre-pend the length to the message, or send a terminator character of some kind.