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Reading entire response through socket with good performance

I have written some code to get a webpage through a proxy using sockets. In essence, it works but reading the response has some strange behavior that is really tripping me up.
When I go to read the response after sending the GET command it is 0 bytes. It takes a few ticks before there is data to read. I don't want to hard code a delay in here as I am trying to write performant reliable code so I have coded a while loop that keeps reading the response until it more than 0.
This works for the first chunk but trying to read subsequent chunks is a problem. If i instantly try to read the response it will be 0 bytes so I need to check the subsequent reads also if they are greater than 0.
So to read the whole response I tried to check if the response is equal to the size of the buffer. If it is equal to the size of the buffer then I carry on and try to read another chunk. This has a few issues also. Sometimes the response will read less than the size of the buffer but there is still more to come, i guess I am reading it faster than they are sending it because if I add a Thread.Sleep() then the buffer will always be full but I don't think it is good practice to hardcode this because I don't know how fast they will be sending. This code will be used for multiple things and will be running on hundreds of threads so performance is everything.
Also if the last chunk just happens to be the size of my buffer then I think the loop will lock, This whole approach I have taken is horrible but I can't see how I should be reading it. I have seen the asynchronous examples but I think that will add to the overall complexity of my code as I just have 1 set process which I will run in many threads.
How do I efficiently read the response when I can't guarantee the next chunk will have data or be full even if there is more data to come?
Sorry for long text but I wanted to explain my thinking. Here is my code:
// Data buffer for incoming data.
byte[] bytes = new byte[1024];
// Connect to a remote device.
try
{
var proxyIpAddress = IPAddress.Parse("123.123.123.123"); //omitted
IPEndPoint remoteEP = new IPEndPoint(proxyIpAddress, 60099);
// Create a TCP/IP socket.
Socket sender = new Socket(proxyIpAddress.AddressFamily,
SocketType.Stream, ProtocolType.Tcp);
// Connect the socket to the remote endpoint. Catch any errors.
try
{
sender.Connect(remoteEP);
Console.WriteLine("Socket connected to {0}",
sender.RemoteEndPoint.ToString());
sender.Send(Encoding.ASCII.GetBytes($"CONNECT google.com:80 HTTP/1.0\r\n\r\n"));
int bytesRec = 0;
while (bytesRec == 0)
{
// Receive the response from the remote device.
bytesRec = sender.Receive(bytes);
Console.WriteLine("{0}",
Encoding.ASCII.GetString(bytes, 0, bytesRec));
}
//clear buffer
bytes = new byte[1024];
bytesRec = 0;
sender.Send(Encoding.ASCII.GetBytes("GET / HTTP/1.0\r\n\r\n"));
//wait for response
while (bytesRec == 0) //if i dont add this it returns before it actually gets data
{
// Receive the response from the remote device.
bytesRec = sender.Receive(bytes);
Console.WriteLine("{0}",
Encoding.ASCII.GetString(bytes, 0, bytesRec));
}
if(bytes.Length == bytesRec) //full buffer so likely more but maybe not if final packet exactly 1024?
{
while (bytes.Length == bytesRec) //again if i miss this it returns too early
{
int subsequentBytes = 0;
while(subsequentBytes == 0) //this can get stuck if last packet exactly size of buffer i think
{
subsequentBytes = sender.Receive(bytes);
Console.WriteLine("{0}",
Encoding.ASCII.GetString(bytes, 0, subsequentBytes));
//this doesn't work. even when there are subsequent bytes sometimes it reads less
//than the size of the buffer so it exits prematurely. If I add a Thread.Sleep() here
// then it works but I don't want to hardcode the delay. How do I read this buffer properly?
Thread.Sleep(1000);
if (subsequentBytes > 0) bytesRec = subsequentBytes;
}
}
}
// Release the socket.
sender.Shutdown(SocketShutdown.Both);
sender.Close();
}
catch (Exception e)
{
Console.WriteLine("Unexpected exception : {0}", e.ToString());
}
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
I understand this is difficult to follow and a lot of writing so if anyone perseveres with this they have my gratitude as the only option I can see is hardcoded pauses which will hurt performance and may still have issues.
EDIT
I have done some experiementing with different servers. If I ping the server then set a Thread.Sleep(pingValue) it works fine but if i set the sleep to lower than ping i get same issue.
Is there some good way with the .net libraries to account for this latency so I am not under/overestimating?

Asynchronous Client Socket, increasing the buffer size

I've implemented an Asynchronous Client Socket extremely similar to this example. Is there any reason why I cannot dramatically increase this buffer size? In this example the buffer size is 256 bytes. In many cases, my application ends up receiving data that is 5,000++ bytes of data. Should I increase the buffer size? Are there any reasons why I should NOT increase the buffer size?
Every once in a long while I'll get some issue where the data comes in out of order or a chunk is missing (yet to be confirmed exactly which it is). For example, one time I received some corrupt data that looks like this
Slice Id="0" layotartX='100'
The attribute called layotartX does not exist in my data, it was supposed to say layout=... but instead the layout got cut off and other data was appended to it later. I counted the bytes and noticed that it was cut off at exactly 256 bytes which just so happens to be my buffer size. It's very possible that increasing my buffer size would prevent this problem from happening (data coming in out of order??). Anyways, as stated in the 1st paragraph, I'm just asking if there is any reason I should NOT increase the buffer size to be say like 5,000 bytes or even 10,000 bytes.
Adding some code. Below is my modified ReceiveCallback function (see the linked example code above for the rest of the classes. When the ReceiveCallback receives data, it calls the "ReceiveSomeData" function which I've also posted below. For some reason every once in a while I get data out of order or pieces missing. The "ReceiveSomeData" function is in a class called "MyChitterChatter" and the "ReceiveCallback" function is in a class called "AsyncClient". So when you see the ReceiveSomeData function locking "this", it's locking the MyChitterChatter class. Is there were my problem could by lying?
private static void ReceiveCallback( IAsyncResult ar )
{
AppDelegate appDel = (AppDelegate)UIApplication.SharedApplication.Delegate;
try {
// Retrieve the state object and the client socket
// from the asynchronous state object.
StateObject state = (StateObject) ar.AsyncState;
Socket client = state.workSocket;
// Read data from the remote device.
int bytesRead = client.EndReceive(ar);
if (bytesRead > 0) {
// There might be more data, so store the data received so far.
string stuffWeReceived = Encoding.ASCII.GetString(state.buffer,0,bytesRead);
string debugString = "~~~~~ReceiveCallback~~~~~~ " + stuffWeReceived + " len = " + stuffWeReceived.Length + " bytesRead = " + bytesRead;
Console.WriteLine(debugString);
// Send this data to be received
appDel.wallInteractionScreen.ChitterChatter.ReceiveSomeData(stuffWeReceived);
// Get the rest of the data.
client.BeginReceive(state.buffer,0,StateObject.BufferSize,0,
new AsyncCallback(ReceiveCallback), state);
} else {
// Signal that all bytes have been received.
receiveDone.Set();
}
}
catch (Exception e) {
Console.WriteLine("Error in AsyncClient ReceiveCallback: ");
Console.WriteLine(e.Message);
Console.WriteLine(e.StackTrace);
}
}
public void ReceiveSomeData ( string data )
{
lock(this)
{
DataList_New.Add(data);
// Update the keepalive when we receive ANY data at all
IsConnected = true;
LastDateTime_KeepAliveReceived = DateTime.Now;
}
}

Yes, you absolutely should increase the buffer size to something much closer to what you expect to get in a single read. 32k or 64k would be fine choice for most uses.
Having said that, data never comes in "out of order" or "missing a chunk" if you're using a TCP/IP socket; if you see something like that, it's a bug in your code, not a bug in the socket. Share your code if you want help.

How to get the Socket Buffer size in C#

I have a Socket code which is communicating through TCP/IP.The machine to which i am communicating has buffer data in its buffer.At present i am trying to get the buffer data using this code.
byte data = new byte[1024];
int recv = sock.Receive(data);
stringData = Encoding.ASCII.GetString(data, 0, recv);
But this code retrieves only 11 lines of data whereas more data is there in the machines buffer.Is this because i have used int recv = sock.Receive(data); and data is 1024 ?
If yes ,How to get the total buffer size and retrieve it into string.

If you think you are missing some data, then you need to check recv and almost certainly: loop. Fortunately, ASCII is always single byte - in most other encodings you would also have to worry about receiving partial characters.
A common approach is basically:
int recv;
while((recv = sock.Receive(data)) > 0)
{
// process recv-many bytes
// ... stringData = Encoding.ASCII.GetString(data, 0, recv);
}
Keep in mind that there is no guarantee that stringData will be any particular entire unit of work; what you send is not always what you receive, and that could be a single character, 14 lines, or the second half of one word and the first half of another. You generally need to maintain your own back-buffer of received data until you have a complete logical frame to process.
Note, however, Receive always tries to return something (at least one byte), unless the inbound stream has closed - and will block to do so. If this is a problem, you may need to check the available buffer (sock.Available) to decide whether to do synchronous versus asynchronous receive (i.e. read synchronously while data is available, otherwise request an asynchronous read).

Try something along these lines:
StringBuilder sbContent=new StringBuilder();
byte data = new byte[1024];
int numBytes;
while ((numBytes = sock.Receive(data))>0)
{
sbContent.Append(Encoding.UTF8.GetString(data));
}
// use sbContent.ToString()

Socket tcpSocket = new Socket(ipe.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
Console.WriteLine(" ReceiveBufferSize {0}", tcpSocket.ReceiveBufferSize);
For actual data you can put below condition:-
int receiveBytes;
while((receiveBytes = tcpSocket.Receive.Data(receiveBytes)) > 0)
{
}

Understanding the NetworkStream.EndRead()-example from MSDN

I tried to understand the MSDN example for NetworkStream.EndRead(). There are some parts that i do not understand.
So here is the example (copied from MSDN):
// Example of EndRead, DataAvailable and BeginRead.
public static void myReadCallBack(IAsyncResult ar ){
NetworkStream myNetworkStream = (NetworkStream)ar.AsyncState;
byte[] myReadBuffer = new byte[1024];
String myCompleteMessage = "";
int numberOfBytesRead;
numberOfBytesRead = myNetworkStream.EndRead(ar);
myCompleteMessage =
String.Concat(myCompleteMessage, Encoding.ASCII.GetString(myReadBuffer, 0, numberOfBytesRead));
// message received may be larger than buffer size so loop through until you have it all.
while(myNetworkStream.DataAvailable){
myNetworkStream.BeginRead(myReadBuffer, 0, myReadBuffer.Length,
new AsyncCallback(NetworkStream_ASync_Send_Receive.myReadCallBack),
myNetworkStream);
}
// Print out the received message to the console.
Console.WriteLine("You received the following message : " +
myCompleteMessage);
}
It uses BeginRead() and EndRead() to read asynchronously from the network stream.
The whole thing is invoked by calling
myNetworkStream.BeginRead(someBuffer, 0, someBuffer.Length, new AsyncCallback(NetworkStream_ASync_Send_Receive.myReadCallBack), myNetworkStream);
somewhere else (not displayed in the example).
What I think it should do is print the whole message received from the NetworkStream in a single WriteLine (the one at the end of the example). Notice that the string is called myCompleteMessage.
Now when I look at the implementation some problems arise for my understanding.
First of all: The example allocates a new method-local buffer myReadBuffer. Then EndStream() is called which writes the received message into the buffer that BeginRead() was supplied. This is NOT the myReadBuffer that was just allocated. How should the network stream know of it? So in the next line numberOfBytesRead-bytes from the empty buffer are appended to myCompleteMessage. Which has the current value "". In the last line this message consisting of a lot of '\0's is printed with Console.WriteLine.
This doesn't make any sense to me.
The second thing I do not understand is the while-loop.
BeginRead is an asynchronous call. So no data is immediately read. So as I understand it, the while loop should run quite a while until some asynchronous call is actually executed and reads from the stream so that there is no data available any more. The documentation doesn't say that BeginRead immediately marks some part of the available data as being read, so I do not expect it to do so.
This example does not improve my understanding of those methods. Is this example wrong or is my understanding wrong (I expect the latter)? How does this example work?

I think the while loop around the BeginRead shouldn't be there. You don't want to execute the BeginRead more than ones before the EndRead is done. Also the buffer needs to be specified outside the BeginRead, because you may use more than one reads per packet/buffer.
There are some things you need to think about, like how long are my messages/blocks (fixed size). Shall I prefix it with a length. (variable size) <datalength><data><datalength><data>
Don't forget it is a Streaming connection, so multiple/partial messages/packets can be read in one read.
Pseudo example:
int bytesNeeded;
int bytesRead;
public void Start()
{
bytesNeeded = 40; // u need to know how much bytes you're needing
bytesRead = 0;
BeginReading();
}
public void BeginReading()
{
myNetworkStream.BeginRead(
someBuffer, bytesRead, bytesNeeded - bytesRead,
new AsyncCallback(EndReading),
myNetworkStream);
}
public void EndReading(IAsyncResult ar)
{
numberOfBytesRead = myNetworkStream.EndRead(ar);
if(numberOfBytesRead == 0)
{
// disconnected
return;
}
bytesRead += numberOfBytesRead;
if(bytesRead == bytesNeeded)
{
// Handle buffer
Start();
}
else
BeginReading();
}

Are there well-known patterns for asynchronous network code in C#?

I recently wrote a quick-and-dirty proof-of-concept proxy server in C# as part of an effort to get a Java web application to communicate with a legacy VB6 application residing on another server. It's ridiculously simple:
The proxy server and clients both use the same message format; in the code I use a ProxyMessage class to represent both requests from clients and responses generated by the server:
public class ProxyMessage
{
int Length; // message length (not including the length bytes themselves)
string Body; // an XML string containing a request/response
// writes this message instance in the proper network format to stream
// (helper for response messages)
WriteToStream(Stream stream) { ... }
}
The messages are as simple as could be: the length of the body + the message body.
I have a separate ProxyClient class that represents a connection to a client. It handles all the interaction between the proxy and a single client.
What I'm wondering is are they are design patterns or best practices for simplifying the boilerplate code associated with asynchronous socket programming? For example, you need to take some care to manage the read buffer so that you don't accidentally lose bytes, and you need to keep track of how far along you are in the processing of the current message. In my current code, I do all of this work in my callback function for TcpClient.BeginRead, and manage the state of the buffer and the current message processing state with the help of a few instance variables.
The code for my callback function that I'm passing to BeginRead is below, along with the relevant instance variables for context. The code seems to work fine "as-is", but I'm wondering if it can be refactored a bit to make it clearer (or maybe it already is?).
private enum BufferStates
{
GetMessageLength,
GetMessageBody
}
// The read buffer. Initially 4 bytes because we are initially
// waiting to receive the message length (a 32-bit int) from the client
// on first connecting. By constraining the buffer length to exactly 4 bytes,
// we make the buffer management a bit simpler, because
// we don't have to worry about cases where the buffer might contain
// the message length plus a few bytes of the message body.
// Additional bytes will simply be buffered by the OS until we request them.
byte[] _buffer = new byte[4];
// A count of how many bytes read so far in a particular BufferState.
int _totalBytesRead = 0;
// The state of the our buffer processing. Initially, we want
// to read in the message length, as it's the first thing
// a client will send
BufferStates _bufferState = BufferStates.GetMessageLength;
// ...ADDITIONAL CODE OMITTED FOR BREVITY...
// This is called every time we receive data from
// the client.
private void ReadCallback(IAsyncResult ar)
{
try
{
int bytesRead = _tcpClient.GetStream().EndRead(ar);
if (bytesRead == 0)
{
// No more data/socket was closed.
this.Dispose();
return;
}
// The state passed to BeginRead is used to hold a ProxyMessage
// instance that we use to build to up the message
// as it arrives.
ProxyMessage message = (ProxyMessage)ar.AsyncState;
if(message == null)
message = new ProxyMessage();
switch (_bufferState)
{
case BufferStates.GetMessageLength:
_totalBytesRead += bytesRead;
// if we have the message length (a 32-bit int)
// read it in from the buffer, grow the buffer
// to fit the incoming message, and change
// state so that the next read will start appending
// bytes to the message body
if (_totalBytesRead == 4)
{
int length = BitConverter.ToInt32(_buffer, 0);
message.Length = length;
_totalBytesRead = 0;
_buffer = new byte[message.Length];
_bufferState = BufferStates.GetMessageBody;
}
break;
case BufferStates.GetMessageBody:
string bodySegment = Encoding.ASCII.GetString(_buffer, _totalBytesRead, bytesRead);
_totalBytesRead += bytesRead;
message.Body += bodySegment;
if (_totalBytesRead >= message.Length)
{
// Got a complete message.
// Notify anyone interested.
// Pass a response ProxyMessage object to
// with the event so that receivers of OnReceiveMessage
// can send a response back to the client after processing
// the request.
ProxyMessage response = new ProxyMessage();
OnReceiveMessage(this, new ProxyMessageEventArgs(message, response));
// Send the response to the client
response.WriteToStream(_tcpClient.GetStream());
// Re-initialize our state so that we're
// ready to receive additional requests...
message = new ProxyMessage();
_totalBytesRead = 0;
_buffer = new byte[4]; //message length is 32-bit int (4 bytes)
_bufferState = BufferStates.GetMessageLength;
}
break;
}
// Wait for more data...
_tcpClient.GetStream().BeginRead(_buffer, 0, _buffer.Length, this.ReadCallback, message);
}
catch
{
// do nothing
}
}
So far, my only real thought is to extract the buffer-related stuff into a separate MessageBuffer class and simply have my read callback append new bytes to it as they arrive. The MessageBuffer would then worry about things like the current BufferState and fire an event when it received a complete message, which the ProxyClient could then propagate further up to the main proxy server code, where the request can be processed.

I've had to overcome similar problems. Here's my solution (modified to fit your own example).
We create a wrapper around Stream (a superclass of NetworkStream, which is a superclass of TcpClient or whatever). It monitors reads. When some data is read, it is buffered. When we receive a length indicator (4 bytes) we check if we have a full message (4 bytes + message body length). When we do, we raise a MessageReceived event with the message body, and remove the message from the buffer. This technique automatically handles fragmented messages and multiple-messages-per-packet situations.
public class MessageStream : IMessageStream, IDisposable
{
public MessageStream(Stream stream)
{
if(stream == null)
throw new ArgumentNullException("stream", "Stream must not be null");
if(!stream.CanWrite || !stream.CanRead)
throw new ArgumentException("Stream must be readable and writable", "stream");
this.Stream = stream;
this.readBuffer = new byte[512];
messageBuffer = new List<byte>();
stream.BeginRead(readBuffer, 0, readBuffer.Length, new AsyncCallback(ReadCallback), null);
}
// These belong to the ReadCallback thread only.
private byte[] readBuffer;
private List<byte> messageBuffer;
private void ReadCallback(IAsyncResult result)
{
int bytesRead = Stream.EndRead(result);
messageBuffer.AddRange(readBuffer.Take(bytesRead));
if(messageBuffer.Count >= 4)
{
int length = BitConverter.ToInt32(messageBuffer.Take(4).ToArray(), 0); // 4 bytes per int32
// Keep buffering until we get a full message.
if(messageBuffer.Count >= length + 4)
{
messageBuffer.Skip(4);
OnMessageReceived(new MessageEventArgs(messageBuffer.Take(length)));
messageBuffer.Skip(length);
}
}
// FIXME below is kinda hacky (I don't know the proper way of doing things...)
// Don't bother reading again. We don't have stream access.
if(disposed)
return;
try
{
Stream.BeginRead(readBuffer, 0, readBuffer.Length, new AsyncCallback(ReadCallback), null);
}
catch(ObjectDisposedException)
{
// DO NOTHING
// Ends read loop.
}
}
public Stream Stream
{
get;
private set;
}
public event EventHandler<MessageEventArgs> MessageReceived;
protected virtual void OnMessageReceived(MessageEventArgs e)
{
var messageReceived = MessageReceived;
if(messageReceived != null)
messageReceived(this, e);
}
public virtual void SendMessage(Message message)
{
// Have fun ...
}
// Dispose stuff here
}

I think the design you've used is fine that's roughly how I would and have done the same sort of thing. I don't think you'd gain much by refactoring into additional classes/structs and from what I've seen you'd actually make the solution more complex by doing so.
The only comment I'd have is as to whether the two reads where the first is always the messgae length and the second always being the body is robust enough. I'm always wary of approaches like that as if they somehow get out of sync due to an unforseen circumstance (such as the other end sending the wrong length) it's very difficult to recover. Instead I'd do a single read with a big buffer so that I always get all the available data from the network and then inspect the buffer to extract out complete messages. That way if things do go wrong the current buffer can just be thrown away to get things back to a clean state and only the current messages are lost rather than stopping the whole service.
Actually at the moment you would have a problem if you message body was big and arrived in two seperate receives and the next message in line sent it's length at the same time as the second half of the previous body. If that happened your message length would end up appended to the body of the previous message and you'd been in the situation as desecribed in the previous paragraph.

You can use yield return to automate the generation of a state machine for asynchronous callbacks. Jeffrey Richter promotes this technique through his AsyncEnumerator class, and I've played around with the idea here.

There's nothing wrong with the way you've done it. For me, though, I like to separate the receiving of the data from the processing of it, which is what you seem to be thinking with your proposed MessageBuffer class. I have discussed that in detail here.