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);
}
}
Related
I have been struggling to fix my mistake. My client/server seems to work fine when on the same machine. When the code is executed on a different PC, for some reason only part of the bytes are reaching the server. I cannot seem to get the bytes to go through to matter how much I try. It seems the cutoff point is 367 bytes and it does not want to transfer anymore. If anyone knows what I am doing wrong, a solution would be much appreciated.
Thanks in advance!
Server:
using System;
using System.Data.SQLite;
using System.IO;
using System.Net;
using System.Net.Sockets;
using System.Runtime.Serialization.Formatters.Binary;
using System.Text;
using System.Threading;
namespace DMAssist
{
// State object for reading client data asynchronously
public class StateObject
{
// Client socket.
public Socket workSocket = null;
// Size of receive buffer.
public const int BufferSize = 1024;
// Receive buffer.
public byte[] buffer = new byte[BufferSize];
// Received data string.
public StringBuilder sb = new StringBuilder();
// Current URL string
}
public class asyncserver
{
public asyncserver()
{
}
// Thread signal.
public static ManualResetEvent allDone = new ManualResetEvent(false);
public static string GetLocalIPAddress()
{
var host = Dns.GetHostEntry(Dns.GetHostName());
foreach (var ip in host.AddressList)
{
if (ip.AddressFamily == AddressFamily.InterNetwork)
{
return ip.ToString();
}
}
throw new Exception("Local IP Address Not Found!");
}
public void StartListening()
{
// Data buffer for incoming data.
byte[] bytes = new Byte[1024];
// Establish the local endpoint for the socket.
// The DNS name of the computer
// running the listener is "host.contoso.com".
IPHostEntry ipHostInfo = Dns.Resolve(Dns.GetHostName());
IPAddress ipAddress = ipHostInfo.AddressList[0];
IPEndPoint localEndPoint = new IPEndPoint(ipAddress, 25599);
// Create a TCP/IP socket.
Socket listener = new Socket(AddressFamily.InterNetwork,
SocketType.Stream, ProtocolType.Tcp);
// Bind the socket to the local endpoint and listen for incoming connections.
try
{
listener.Bind(localEndPoint);
listener.Listen(100);
while (true)
{
// Set the event to nonsignaled state.
allDone.Reset();
// Start an asynchronous socket to listen for connections.
Console.WriteLine("Waiting for a connection...");
listener.BeginAccept(
new AsyncCallback(AcceptCallback),
listener);
// Wait until a connection is made before continuing.
allDone.WaitOne();
}
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
Console.WriteLine("\nPress ENTER to continue...");
Console.Read();
}
public void AcceptCallback(IAsyncResult ar)
{
// Signal the main thread to continue.
allDone.Set();
// Get the socket that handles the client request.
Socket listener = (Socket)ar.AsyncState;
Socket handler = listener.EndAccept(ar);
// Create the state object.
StateObject state = new StateObject();
state.workSocket = handler;
handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
new AsyncCallback(ReadCallback), state);
}
public byte[] ObjectToByteArray(object obj)
{
if (obj == null)
return null;
BinaryFormatter bf = new BinaryFormatter();
MemoryStream ms = new MemoryStream();
bf.Serialize(ms, obj);
return ms.ToArray();
}
private Object ByteArrayToObject(byte[] arrBytes)
{
MemoryStream memStream = new MemoryStream();
BinaryFormatter binForm = new BinaryFormatter();
memStream.Write(arrBytes, 0, arrBytes.Length);
memStream.Seek(0, SeekOrigin.Begin);
Object obj = (Object)binForm.Deserialize(memStream);
return obj;
}
public void ReadCallback(IAsyncResult ar)
{
String content = String.Empty;
String connectedAddress = String.Empty;
// Retrieve the state object and the handler socket
// from the asynchronous state object.
StateObject state = (StateObject)ar.AsyncState;
Socket handler = state.workSocket;
IPEndPoint remoteIpEndPoint = handler.RemoteEndPoint as IPEndPoint;
connectedAddress = remoteIpEndPoint.Address.ToString();
// Read data from the client socket.
int bytesRead = handler.EndReceive(ar);
if (bytesRead > 0)
{
Console.WriteLine("Bytes read: " + bytesRead);
// There might be more data, so store the data received so far.
state.sb.Append(Encoding.ASCII.GetString(
state.buffer, 0, bytesRead));
object rawbytes = ByteArrayToObject(state.buffer);
netObject recvobject = (netObject)rawbytes;
Send(handler, (object)recvobject);
}
}
private void Send(Socket handler, object data)
{
// Convert the string data to byte data using ASCII encoding.
byte[] byteData = ObjectToByteArray(data);
// Begin sending the data to the remote device.
handler.BeginSend(byteData, 0, byteData.Length, 0,
new AsyncCallback(SendCallback), handler);
}
private static void SendCallback(IAsyncResult ar)
{
try
{
// Retrieve the socket from the state object.
Socket handler = (Socket)ar.AsyncState;
// Complete sending the data to the remote device.
int bytesSent = handler.EndSend(ar);
Console.WriteLine("Sent {0} bytes to client.", bytesSent);
handler.Shutdown(SocketShutdown.Both);
handler.Close();
}
catch (Exception e)
{
Console.WriteLine(e.ToString());
}
}
}
}
Client:
using System;
using System.Net;
using System.Net.Sockets;
using System.Threading;
using System.Text;
using System.Windows.Forms;
using System.Runtime.Serialization.Formatters.Binary;
using System.IO;
using System.Collections;
namespace DMAssist
{
public class asyncsclient {
public asyncsclient()
{
}
public byte[] ObjectToByteArray(object obj)
{
if (obj == null)
return null;
BinaryFormatter bf = new BinaryFormatter();
MemoryStream ms = new MemoryStream();
bf.Serialize(ms, obj);
return ms.ToArray();
}
private Object ByteArrayToObject(byte[] arrBytes)
{
MemoryStream memStream = new MemoryStream();
BinaryFormatter binForm = new BinaryFormatter();
memStream.Write(arrBytes, 0, arrBytes.Length);
memStream.Seek(0, SeekOrigin.Begin);
Object obj = (Object)binForm.Deserialize(memStream);
return obj;
}
static byte[] GetBytes(string str)
{
byte[] bytes = new byte[str.Length * sizeof(char)];
System.Buffer.BlockCopy(str.ToCharArray(), 0, bytes, 0, bytes.Length);
return bytes;
}
static string GetString(byte[] bytes)
{
char[] chars = new char[bytes.Length / sizeof(char)];
System.Buffer.BlockCopy(bytes, 0, chars, 0, bytes.Length);
return new string(chars);
}
public object sendObject(object outgoingObject, bool expectRecieve)
{
try
{
Socket soc = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
IPAddress ip = IPAddress.Parse("x.x.x.x");
IPEndPoint remoteEP = new IPEndPoint(ip, 25599);
soc.Connect(remoteEP);
byte[] byData = ObjectToByteArray(outgoingObject);
//Console.WriteLine("Array length:" + byData.Length);
soc.Send(byData);
if (expectRecieve)
{
byte[] buffer = new byte[1024];
int iRx = soc.Receive(buffer);
object rawbytes = ByteArrayToObject(buffer);
netObject recvobject = (netObject)rawbytes;
Console.WriteLine("Writing stopped");
soc.Close();
soc.Dispose();
return recvobject;
}
else
{
soc.Close();
soc.Dispose();
return "";
}
}
catch (Exception)
{
MessageBox.Show("Server unreachable. Make sure server is broadcasting on port 25599 successfully.", "DMAssist Error 0xC1");
}
return null;
}
}
}
There is a big difference between UDP sockets and TCP sockets.
What you are trying would work better with UDP because this protocol is more packet oriented. This means that if a server sends a certain number of bytes, the client 'might' receive the same certain number of bytes or receive nothing at all.
For TCP it is different because it is a streaming protocol which means bytes are just sent sequentially anyway the server sees fit. Usually it will try to fill up to the mtu and when you receive you will very likely receive the data in multiple chunks that you have to append yourself. TCP is a also connection oriented and reliable. Bytes are acked from the client to the server and vice versa, and retransmitted if an ack is not received in due time. This means even that packets can at the TCP level be received out of order. TCP will fit them together. You at the application level will receive everything in order.
The advice you got so far is correct, you have to keep calling receive. And this until there is nothing to receive anymore. And how do you know that there is nothing to receive anymore ? Usually that is detected by receiving a TCP message in receive with 0 length. This means that the peer has closed its end of the socket and will not send anymore. This in turn means that you can close your end of the socket.
This is by design. And it's a very common mistake developers make with regards to sockets.
To receive data correctly, you need to keep receiving data in a loop until you receive the number of bytes you need. Keep appending to your receive buffer until you get the number of bytes you need.
Some socket implementations have a the concept of a "wait for all" flag (e.g. MSG_WAITALL), but even that will return partial data if the remote closed the connection after sending.
Code defensively. Code as if the sender is only going to send 1 byte at a time. You'll be in good shape.
As you mentioned in your code, There might be more data, so you store the data received so far. But you don't have the code get the rest of the data.
MSDN has an example on how to do this correctly:
https://msdn.microsoft.com/en-us/library/bew39x2a.aspx?f=255&MSPPError=-2147217396
From winsock2.h:
#define MSG_WAITALL 0x8 /* do not complete until packet is completely filled */
You can add this option to your .net stream socket receive like this:
socket.Receive(buffer, (SocketFlags)0x8)
This should preserve message boundaries much like you're accustomed with dgram sockets.
I have a little complication i encounter.
I may not be expert in TCP Connections but i hope someone here would help me.
This is my Client Code:
void Connect(String server, String message)
{
try
{
Int32 port = 8968;
TcpClient client = new TcpClient(server, port);
Byte[] data = File.ReadAllBytes(curSelectedFile);
NetworkStream stream = client.GetStream();
Byte[] fileData = File.ReadAllBytes(curSelectedFile);
Byte[] msgData = Encoding.ASCII.GetBytes("SendFile");
Byte[] sendData = new byte[fileData.Length + msgData.Length];
// Copy data to send package.
msgData.CopyTo(sendData, 0);
fileData.CopyTo(sendData, 4);
// Send the message to the connected TcpServer.
stream.Write(data, 0, data.Length);
Console.WriteLine("Sent: {0}", message);
// Receive the TcpServer.response.
// Buffer to store the response bytes.
data = new Byte[256];
// String to store the response ASCII representation.
String responseData = String.Empty;
// Read the first batch of the TcpServer response bytes.
Int32 bytes = stream.Read(data, 0, data.Length);
responseData = System.Text.Encoding.ASCII.GetString(data, 0, bytes);
Console.WriteLine("Received: {0}", responseData);
// Close everything.
stream.Close();
client.Close();
}
catch (ArgumentNullException e)
{
Console.WriteLine("ArgumentNullException: {0}", e);
}
catch (SocketException e)
{
Console.WriteLine("SocketException: {0}", e);
}
Console.WriteLine("\n Press Enter to continue...");
Console.Read();
}
This is my server one:
// Listen loop.
while(true)
{
using (TcpClient tcpClient = myListener.AcceptTcpClient())
{
Console.WriteLine("[Server] Acceptam client.");
using (NetworkStream networkStream = tcpClient.GetStream())
{
// Buffer for reading data
Byte[] bytes = new Byte[1024];
var data = new List<byte>();
int length;
while ((length = networkStream.Read(bytes, 0, bytes.Length)) != 0)
{
var copy = new byte[length];
Array.Copy(bytes, 0, copy, 0, length);
data.AddRange(copy);
}
// Incercam sa vedem ce doreste clientul.
string msg = Encoding.ASCII.GetString(data[0], 0, length);
if(msg.StartsWith("SendFile"))
{
using (Stream stream = new FileStream(#"C:\test.mp3", FileMode.Create, FileAccess.ReadWrite))
{
BinaryFormatter binaryFormatter = new BinaryFormatter();
networkStream.Position = 4;
binaryFormatter.Serialize(networkStream, data.ToArray());
}
}
}
}
}
What i'm trying to do here:
- I want the client to send a Message.. like "SaveFile" & after this string to be the filedata.
- The server should read the client message, and to process stuff according to the Client sentstring, before doing something with the file.
I believe that i don't know how to do it.
May i have an example on how to send/receive and read certain strings from the beggining of the file? How i can put them in the byte array and how to read it... It's quite overwhelming..
PS: The current Server Code is reading the data and CAN write as i coded it, without losing any packages. But also he's writing the aditional packets i sent before i converted the bytes of the file.
networkStream.Position = 4; isn't legal, because NetworkStream is not seekable.
I would discourage you from mixing text and binary data, just because of the complication it makes in the application protocol. But if you really want to do that, you should use BinaryWriter and BinaryReader, because it can write strings to a stream which can then be read later without consuming the bytes after the string.
Then you can do something like this...
In the client:
BinaryWriter writer = new BinaryWriter(networkStream);
writer.Write("SendFile");
writer.Write(fileData.Length);
writer.Write(fileData);
In the server:
BinaryReader reader = new BinaryReader(networkStream);
switch (reader.ReadString())
{
case "SendFile":
{
int length = reader.ReadInt32();
byte[] fileData = reader.ReadBytes(length);
// ... then do whatever with fileData, like write to a file
break;
}
}
The BinaryWriter/Reader implementation of the length-counted string is non-standard, so if you wanted to interact with any other non-.NET code using this technique, it would be more complicated because you have to replicate/reimplement the non-standard length-counting logic yourself.
IMHO a better approach is to encode commands as fixed-length data, e.g. an 8-, 16-, or 32-bit value, which is just some integer that specifies the command. Then you can list your commands in the code as an enum type, casting to/from the network stream for the I/O. This would be more portable, easier to implement on non-.NET platforms.
Server program C#
private TcpListener serverSocket;
..
init:
serverSocket = new TcpListener(ipAddress, port_number);
when new connection request found:
TcpClient clientSock = default(TcpClient);
clientSock = serverSocket.AcceptTcpClient();
NetworkStream networkStream = clientSocket.GetStream();
String FileName = requested binary data file name from client
Byte[] sendBytes = null;
if (File.Exists(pkgName))
{
//load file contents
sendBytes = File.ReadAllBytes(pkgName);
}
if (sendBytes != null)
{
networkStream.Write(sendBytes, 0, sendBytes.Length); //sendBytes.Length = 1001883;
networkStream.Flush();
}
...
Java Android code: client
InetAddress serverAddr = InetAddress.getByName(serverIp);
Log.d("SideloadManager", "C: Connecting...");
Socket socket = new Socket(serverAddr, serverPort);
InputStream inFromServer = socket.getInputStream();
DataInputStream in = new DataInputStream(inFromServer);
FileOutputStream outStream = new FileOutputStream("...\recieved.bmp");
int size = 1001883; //same size from server
byte[] buf = new byte[size];
in.read(buf);
outStream.write(buf, 0, buf.length);
outStream.flush();
outStream.close();
received.bmp is of same size as on server 1001883 bytes. But its contents gets corrupted. After debugging i have seen that:
on C# program byte array is [ 149, 145, 10, .....]
on Java program byte array is: [ -105, -101, 10, .....] this is due to signed byte in java
What am i missing to receive correct bitmap?
SOLVED as below:
Replace:
int size = 1001883; //same size from server
byte[] buf = new byte[size];
in.read(buf);
outStream.write(buf, 0, buf.length);
with this:
int len=-1;
byte[] buf = new byte[1024];
while ((len = in.read(buf, 0, buf.length)) > 0) {
outStream.write(buf, 0, len);
}
solved the issue :)
The data is transferred correctly because 149 and -105 have the same binary representation as bytes. The more likely problem is that you're not reading all of the data that was sent in the java side.
The read method returns the number of bytes that have been read, and -1 when the end of the stream has been reached. You need a loop to read the entire file:
int bytesRead;
while ((bytesRead = in.read(buf)) != -1) {
outStream.write(buf, 0, bytesRead);
}
I'm creating a socket server that needs to continuously listen for incoming messages from the connected clients. Those messages will be sent in a byte[] array. I had the server working great with a StreamReader but StreamReader only works with textual represenations of the data being sent...not byte[] arrays.
Here's what I had:
StreamReader reader = new StreamReader(Client.GetStream());
string line = "";
while (true)
{
line = reader.ReadLine();
if (!string.IsNullOrEmpty(line))
{
parentForm.ApplyText(line + "\r\n");
SocketServer.SendBroadcast(line);
}
}
I need to now convert that into a raw stream somehow that will convert the stream contents into a byte[] array but I can't seem to get a handle on it.
I tried this:
while (true)
{
var bytes = default(byte[]);
using (var memstream = new MemoryStream())
{
var buffer = new byte[512];
var bytesRead = default(int);
while ((bytesRead = reader.BaseStream.Read(buffer, 0, buffer.Length)) > 0)
memstream.Write(buffer, 0, bytesRead);
bytes = memstream.ToArray();
}
//parentForm.ApplyText(bytes.Length + "\r\n");
}
but as you might guess, the while(true) loop doesn't quite work how I need it to. Can anyone help me with some code adjustment to make this work as I need it to. It needs to continuously listen for incoming messages, then when a message is received, it needs to do something with that message (the byte[] array) then go back to listening again.
TIA
I guess "listening continuously" is not task of reader its a task of listener. I ran into same problem when i was writing server using TcpListener. I am not sure what you want to do but i am posting solution for your "listening continuous" and reading into byte[] problem. I guess this code might help you:
TcpListener t = new TcpListener(IPAddress.Loopback, _port);
t.Start();
Console.WriteLine("Server is started and waiting for client\n\n");
byte[] buff = new byte[255];
NetworkStream stream;
TcpClient client;
while(true)
{
client = t.AcceptTcpClient();
if (!client.Connected)
return;
stream = client.GetStream();
while ((stream.Read(buff, 0, buff.Length)) != 0)
{
break;
}
if (0 != buff.Length)
break;
}
There's no need to convert anything. GetStream() returns a NetworkStream. See the sample Microsoft includes in the NetworkStream.Read Method. All you have to do is replace the myCompleteMessage.AppendFormat("{0}", Encoding.ASCII.GetString(myReadBuffer, 0, numberOfBytesRead)); line with an appropriate storage mechanism.
I have problem with sending objects via TCPClient. At first, I serialize them into byte array and then I send them. TCPListener recieves some data, but deserializer is throwing exception "Unexpected end of stream".
Here is reciever code:
public void start()
{
TcpListener listener = new TcpListener(IPAddress.Any, 8090);
listener.Start();
while (true)
{
TcpClient client = listener.AcceptTcpClient();
processClient(client);
}
}
public void processClient(TcpClient client)
{
NetworkStream net = client.GetStream();
ReadData(net);
byte[] response = Encoding.UTF8.GetBytes("Hello from the server.");
net.Write(response, 0, response.Length);
net.Close();
client.Close();
}
void ReadData(NetworkStream netstream)
{
byte[] buffer = new byte[2048];
System.IO.MemoryStream memStream = new System.IO.MemoryStream();
netstream.ReadTimeout = 5000;
int bytes = -1;
while ((bytes = netstream.ReadByte()) != -1)
{
memStream.WriteByte((byte)bytes);
}
System.Runtime.Serialization.Formatters.Binary.BinaryFormatter bform = new System.Runtime.Serialization.Formatters.Binary.BinaryFormatter();
Packet packet = (Packet)bform.Deserialize(memStream);
OnMessageArrived(this, new MessageEventArgs(packet.From.ToString(), packet.Data.ToString()));
memStream.Close();
netstream.Close();
}
And here is sender code:
public void sendData(string to, Packet data)
{
TcpClient client = new TcpClient();
MemoryStream mstream = new MemoryStream();
client.Connect(new IPEndPoint(IPAddress.Parse("127.0.0.1"), 8090));
if (client.Connected)
{
NetworkStream stream = client.GetStream();
System.Runtime.Serialization.Formatters.Binary.BinaryFormatter bform = new System.Runtime.Serialization.Formatters.Binary.BinaryFormatter();
bform.Serialize(mstream, data);
byte[] buffer = new byte[2048];
mstream.Read(buffer, 0, buffer.Length);
stream.Write(buffer, 0, buffer.Length);
stream.Flush();
stream.Close();
client.Close();
}
}
Sender main method:
static void Main(string[] args)
{
SimplestTCPIP.Client client = new SimplestTCPIP.Client();
Packet packet = new Packet("client", "server", IPAddress.Parse("127.0.0.1"));
client.sendData("server", packet);
Console.WriteLine("IP: " + GetIP().ToString());
Console.Read();
}
Reciever main method:
static void Main(string[] args)
{
SimplestTCPIP.Server server = new SimplestTCPIP.Server();
server.OnMessageArrived += new SimplestTCPIP.Server.MessageArrived(server_OnMessageArrived);
Thread thread = new Thread(server.start);
thread.Start();
}
static void server_OnMessageArrived(object sender, SimplestTCPIP.Server.MessageEventArgs m)
{
Console.WriteLine(m.From + " : " + m.Text);
}
In your sendData method you serialize the object to a memory stream and then read it back into a buffer of 2048 bytes before writing it to the network stream. If the serialzed object is > 2048 bytes you would have a problem. I would try just serializing directly to the network stream or at least using the same kind of code as in your ReadData method where you write byte by byte.
Edit:
The size of the data is probably not the problem. You should still avoid the hard coded buffer size and stick with the code change you mention in the comment. Given your comment the problem lies elsewhere.
In both your sender and your receiver you write to a memory stream and then read from it. You can't do that unless you set the current position in the stream back to zero between the write and read.
So in your sendData method on the client add the line
mstream.Seek(0, SeekOrigin.Begin);
right after
bform.Serialize(mstream, data);
And in the ReadData method of your server add the line
memStream.Seek(0, SeekOrigin.Begin);
right before
Packet packet = (Packet)bform.Deserialize(memStream);
That way the memory stream is set to the beginning before you try and read from it.
I think you could just skip the memory stream all together and just read and write to the network stream, but you might have other reasons for it.