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length header suddenly has wrong value when use read int32?

I wrote a tcp listener to receive a sequence of images from single client , this is the code of server :
new Thread(() =>
{
while (true)
{
displayingFrame.Start(); // another thread to display images
Socket socket = listener.AcceptSocket();
TcpClient client = new TcpClient();
client.Client = socket;
Debug.WriteLine("Connection accepted.");
var childSocketThread = new Thread(() =>
{
NetworkStream ns = client.GetStream();
BinaryReader br = new BinaryReader(ns);
while (true)
{
using (MemoryStream ms = new MemoryStream())
{
int length = br.ReadInt32();
Debug.WriteLine("length : " + length);
byte[] buf = new byte[1024];
int totalReaded = 0;
int readed = 0;
while (totalReaded < length)
{
readed = br.Read(buf, 0, buf.Length);
ms.Write(buf, 0, readed);
totalReaded += readed;
}
byte[] frame = ms.ToArray();
this.frames.Enqueue(frame);
Debug.WriteLine("frame enqueued with length " + frame.Length);
}
}
});
childSocketThread.Start();
}
}).Start();
it receive frames very well but suddenly br.ReadInt32(); returns a very big length so br.Read(buf, 0, buf.Length); takes a very long time writing to memory stream and it writes a wrong data inside frame .
this is the client :
TcpClient client = new TcpClient();
client.Connect(new IPEndPoint(IPAddress.Loopback, 20000));
NetworkStream ns = client.GetStream();
BinaryWriter bw = new BinaryWriter(ns);
while ( true )
{
byte[] frame = Screenshot();
bw.Write(frame.Length);
Console.WriteLine("a frame length has flushed : " + frame.Length);
bw.Write(frame);
Console.WriteLine("a frame itself has flushed");
}
Console.ReadKey();
and here the debug info :

If you check the hex value you're getting - 1196314761 - you'll get 0x474E5089 and finally convert to ASCII you will get GNP\x89 which gives us the known magic value \x89PNG that is the marker of PNG file. You're actually reading the content of your screenshot as the length.
Make sure that you're code for reading the data does not read too much from the previous frame. I think you code for reading the data does not include the fact that you might get content of 2 frames in one .Read but then later you just don't care if you have too much data. You only check if it's not less than length.

out of memory exception in image.fromFile(Stream)

i searched in all similar problem but still couldn't solve the problem
this is a server code it is work successfully and the image File created successfully BUT if i cannot access the image file
image i = Image.FromStream(StreamObject);
NOTES:
1- the image not too large
2- the image have valid image format
I know the problem related to the stream ... how can i control this problem
i want to retrive the saved image in the image object for some reason..
How can i keep the stream open for the lifetime of the image.??
static void Main(string[] args)
{
IPAddress ipAdress = IPAddress.Parse("192.160.1.8");
// Initializes the Listener
TcpListener tcpListener = new TcpListener(ipAdress, 8001);
tcpListener.Start();
int no;
for (;;)
{
Socket socket = tcpListener.AcceptSocket();
if (socket.Connected)
{
Stream os = File.OpenWrite("Target.jpg",);
byte[] buffer = new byte[8000000];
NetworkStream networkStream = new NetworkStream(socket);
no = networkStream.Read(buffer, 0, 8000000);
os.Write(buffer, 0, no);
///here the problem in the following line
///
Image i = Image.FromFile("Target.jpg");
///
networkStream.Close();
socket.Close();
break;
}
}
}

While bytes have been written to the buffer, the bytes may not have been flushed to the disk. Additionally, the code example provided keeps the file open for writing while it is getting read into an image. For things like streams, you should wrap the usage in using statements in order to avoid these types of memory errors.
static void Main(string[] args)
{
IPAddress ipAdress = IPAddress.Parse("192.160.1.8");
// Initializes the Listener
TcpListener tcpListener = new TcpListener(ipAdress, 8001);
tcpListener.Start();
int no;
for (;;)
{
Socket socket = tcpListener.AcceptSocket();
if (socket.Connected)
{
byte[] buffer = new byte[8000000];
using (Stream os = File.OpenWrite("Target.jpg"))
{
using (NetworkStream networkStream = new NetworkStream(socket))
{
no = networkStream.Read(buffer, 0, 8000000);
os.Write(buffer, 0, no);
}
}
///here the problem in the following line
///
Image i = Image.FromFile("Target.jpg");
///
socket.Close();
break;
}
}
}
Alternatively, and probably more appropriately, you should consider creating your GDI+ image directly from the stream using Image.FromStream. The Image.FromStream method is documented here: https://msdn.microsoft.com/en-us/library/system.drawing.image.fromstream%28v=vs.110%29.aspx?f=255&MSPPError=-2147217396

C# sockets: can't read after writing to socket

In my client/server application my client wiil communicate with the server for 2 functions: the client will either request data from the server or it will send data so the server will save it. I'm using one socket for both methods, and the method to be used is defined by the first byte sent. If the first byte is "1" it is requesting data. If it is "2", it will send data (data bytes are sent after the "2" byte). It works perfectly for sending data. But when I'm requesting data it works, as long as I don't read the socket stream in the client. It's like if I make the client read data after sending data, the server will have no data to read, and it just crashes when trying to read the data.
Here is my server code:
private const int BufferSize = 1024;
NetworkStream netstream = null;
byte[] RecData = new byte[BufferSize];
int RecBytes;
try {
netstream = clientSocket.GetStream();
int totalrecbytes = 0;
using (MemoryStream ms = new MemoryStream()) {
//When I get here, there is no data to read
while ((RecBytes = netstream.Read(RecData, 0, RecData.Length)) > 0) {
ms.Write(RecData, 0, RecBytes);
totalrecbytes += RecBytes;
}
byte[] bytes = ms.ToArray();
byte b = bytes[0];
switch (b) {
case 1:
//Here I gather data and put it in "stream" variable
byte[] SendingBuffer = null;
int NoOfPackets = Convert.ToInt32(Math.Ceiling(Convert.ToDouble(stream.Length) / Convert.ToDouble(BufferSize)));
int TotalLength = (int)stream.Length, CurrentPacketLength, counter = 0;
for (int i = 0; i < NoOfPackets; i++) {
if (TotalLength > BufferSize) {
CurrentPacketLength = BufferSize;
TotalLength = TotalLength - CurrentPacketLength;
}
else
CurrentPacketLength = TotalLength;
SendingBuffer = new byte[CurrentPacketLength];
stream.Read(SendingBuffer, 0, CurrentPacketLength);
netstream.Write(SendingBuffer, 0, (int)SendingBuffer.Length);
}
netstream.Flush();
}
catch (Exception e) {
Console.WriteLine("EXCEPTION:\n" + e.ToString());
}
break;
case 2:
//Code to read data
break;
}
}
netstream.Close()
clientSocket.Close();
And here is my client code:
using (System.Net.Sockets.TcpClient clientSocket = new System.Net.Sockets.TcpClient()) {
string returnData = "";
IAsyncResult ar = clientSocket.BeginConnect("127.0.0.1", 8080, null, null);
System.Threading.WaitHandle wh = ar.AsyncWaitHandle;
try {
if (!ar.AsyncWaitHandle.WaitOne(TimeSpan.FromSeconds(5), false)) {
clientSocket.Close();
Console.WriteLine("Timeout");
return;
}
System.Net.Sockets.NetworkStream serverStream = clientSocket.GetStream();
byte b = 1;
byte[] outStream = { b };
serverStream.Write(outStream, 0, outStream.Length);
serverStream.Flush();
//If I comment following lines, the server can read sent data, but server can't otherwise
byte[] RecData = new byte[1024];
int RecBytes;
int totalrecbytes = 0;
MemoryStream MS = new MemoryStream();
while ((RecBytes = serverStream.Read(RecData, 0, RecData.Length)) > 0) {
MS.Write(RecData, 0, RecBytes);
totalrecbytes += RecBytes;
}
serverStream.Close();
clientSocket.Close();
clientSocket.EndConnect(ar);
}
catch (Exception ex) {
Console.WriteLine("Exceção: " + ex.ToString());
}
finally {
wh.Close();
}
}
So, how can I send data to server and read the response? (I tried even putting the thread to sleep after sending data, with no luck.)
Thanks in advance.
EDIT:
With some debug messages I discovered that the server do read the "1" byte that was sent, but somehow it gets stuck inside the while loop, like, the server just stops there, no more loops and it does not leave the while loop. I saw that after writing "loop" in console inside the while loop, and writing read bytes also in console. It wrote "loop" once, and the read byte.

This code worries me:
//When I get here, there is no data to read
while ((RecBytes = netstream.Read(RecData, 0, RecData.Length)) > 0) {
ms.Write(RecData, 0, RecBytes);
totalrecbytes += RecBytes;
}
You are reading until the client closes the connection (or shuts down sending, which you don't do). But the client only closes when the server has replied. The server reply will never come. It is a deadlock.
Solution: Read a single byte to determine the requests command (b).
Unrelated to the question, your "packetised" sending (NoOfPackets, ...) does not seem to serve any purpose. Just use Stream.Copy to write. TCP does not have packets.
An even better solution would be to abandon your custom TCP protocol and use an HTTP library. All these concerns just go away. There are various smaller problems with your code that are very typical to see in TCP code.

"Artifacts" while streaming images in c#

I wanted to create a project for streaming multiple images through net. I just wanted to start with small, functional code but already encountered a funky problem for me. Image is received, but it contains graphical bugs like its only a part of it.
Sadly cant show images cause of low rputation, here is link.
http://img543.imageshack.us/img543/1508/buggedy.jpg
Of course, million dollars for answer. ^^
TcpListener listener;
TcpClient client;
TcpClient datatoclient;
NetworkStream stream;
Host part:
listener = new TcpListener(5000);
listener.Start();
datatoclient = listener.AcceptTcpClient();
NetworkStream nowystream = datatoclient.GetStream();
MemoryStream ms = new MemoryStream();
byte[] image = File.ReadAllBytes("default.jpg");
switch (trackBar1.Value)
{
case 0:
image = File.ReadAllBytes("mirrion.jpg");
break;
case 1:
image = File.ReadAllBytes("tenis.jpg");
break;
case 2:
image = File.ReadAllBytes("marisasold.jpg");
break;
}
// get the image size in bytes
int numberOfBytes = image.Length;
// put the size into an array
byte[] numberOfBytesArray = BitConverter.GetBytes(numberOfBytes);
// send the image size
nowystream.Write(numberOfBytesArray, 0, numberOfBytesArray.Length);
// send the image
nowystream.Write(image, 0, numberOfBytes);
Client part:
client = new TcpClient("127.0.0.1", 5000);
stream = client.GetStream();
byte[] data = new byte[4];
// read the size
stream.Read(data, 0, data.Length);
int size = BitConverter.ToInt32(data, 0);
label1.Text = size.ToString();
// prepare buffer
data = new byte[size];
// load image
stream.Read(data, 0, data.Length);
// save image to file for test
File.WriteAllBytes("received.jpg", data);
MemoryStream MS = new MemoryStream(data);
pictureBox1.Image = Image.FromStream(MS);

stream.Read doesn't guarantee that it will read data.Length bytes. Instead it returns number of bytes read. So you should check its return value and continue reading till you get all the bytes.
See http://msdn.microsoft.com/en-us/library/system.io.stream.read(v=vs.90).aspx (Section Return Value)
Thr read method can be something like this
void Read(Stream stream, byte[] buffer,int offset,int len)
{
int read = 0;
while (read < len)
{
read += stream.Read(buffer, offset + read, len-read);
}
}

Android retrieve bytes from inputstream

I am trying to retrieve the byte that transferred by the server that has been programmed in c# as follow:
static void Main(String[] args){
Socket sListen = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
IPAddress IP = IPAddress.Parse("10.0.0.92");
IPEndPoint IPE = new IPEndPoint(IP, 4321);
sListen.Bind(IPE);
Console.WriteLine("Service is listening ...");
sListen.Listen(2);
while (true){
Socket clientSocket;
try{
clientSocket = sListen.Accept();
}
catch{
throw;
}
byte[] buffer = ReadImageFile("path to image");
clientSocket.Send(buffer, buffer.Length, SocketFlags.None);
Console.WriteLine("Send success!");
}
}
private static byte[] ReadImageFile(String img){
FileInfo fileinfo = new FileInfo(img);
byte[] buf = new byte[fileinfo.Length];
FileStream fs = new FileStream(img, FileMode.Open, FileAccess.Read);
fs.Read(buf, 0, buf.Length);
fs.Close();
//fileInfo.Delete ();
GC.ReRegisterForFinalize(fileinfo);
GC.ReRegisterForFinalize(fs);
return buf;
}
Above codes works fine when I write a client in the c# and run it in the pc. However I want to retrieve the bytes transferred by the server in the android device.
The android connected to the server successfully but it will not finish its job, basically it will not pass the ‘while loop in the bellow code’. I think there is something wrong with the byte length because it’s never get to ‘-1’.
Android java code (Client):
Socket socket = new Socket("ip", 4321);
InputStream is = socket.getInputStream();
byte[] buffer = new byte[1024];
int read = is.read(buffer);
while(read != -1){
read = is.read(buffer);
}
is.close();
socket.close();
I do appreciate any help in advance,
Thanks,

The client read() method will never return -1 until the server closes the connection. You're not doing that so it never happens.

I don't get the point of your Java code. The read(byte[]) method you are using writes 1024 bytes (or less) in the buffer again and again. You are overwriting your previous buffer content. You probably would like to write the downloaded data to somewhere, like an OutputStream. Example:
Socket socket = new Socket("ip", 4321);
InputStream is = socket.getInputStream();
OutputStream os = ...; // Where to save data, for example, new ByteArrayOutputStream();
copyStreams(is, os);
is.close();
socket.close();
public static void copyStreams(InputStream is, OutputStream os) throws IOException {
byte[] buffer = new byte[1024];
int numBytesRead;
for (;;) {
bytesRead = is.read(buffer);
if (bytesRead <= 0)
break;
os.write(buffer, 0, bytesRead);
}
}