I hope to find any help on my old annoying problem.
I have a TCP sever program with java and client program with c#
packet protocol between those two is simply consist of 4byte length & body ASCII data.
The Problem is that C# client faces FormatException which is from parsing fail on length byte. If I look into an error from client side, then client is trying to parse somewhere in the body which is not length header. But apparently, Server does not send broken packet.
meanwhile, at the server, I could find an Broken pipe error whenever this kind of problem happens.
Unfortunately this error does not always happen and was not able to recreate the problem situation. it makes me difficult to find exact cause of this problem
Please see below codes for server side
public class SimplifiedServer {
private Map<InetAddress, DataOutputStream> outMap;
private Map<InetAddress,DataInputStream> inMap;
protected void onAcceptNewClient(Socket client) {
DataOutputStream out = null;
DataInputStream in = null;
try {
out = new DataOutputStream(client.getOutputStream());
in = new DataInputStream(client.getInputStream());
} catch (IOException e) {
e.printStackTrace();
}
outMap.put(client.getInetAddress(), out);
inMap.put(client.getInetAddress(), in);
}
public void writeToAll(String packet) {
outMap.forEach((key, out) -> {
try {
byte[] body = packet.getBytes("UTF-8");
int len = body.length;
if (len > 9999) {
throw new IllegalArgumentException("packet length is longer than 10000, this try will be neglected");
}
String lenStr = String.format("%04d%s", len, packet);
byte[] obuf = lenStr.getBytes();
synchronized (out) {
out.write(obuf);
out.flush();
}
} catch (IOException e) {
e.printStackTrace();
}
});
}
public void listenClient(Socket client) {
try {
DataOutputStream out = outMap.get(client.getInetAddress());
DataInputStream in = inMap.get(client.getInetAddress());
while (true) {
byte[] received = SimplePacketHandler.receiveLpControlerData(in);
byte[] lenBytes = new byte[4];
for( int i = 0 ; i < 4 ; i ++){
lenBytes[i] = in.readByte();
}
String lenString = new String(lenBytes);
int length = Integer.parseInt(lenString);
byte[] data = new byte[length];
for ( int i = 0 ; i < length ; i ++){
data[i] = in.readByte();
}
if ( data == null ){
System.out.println("NetWork error, closing socket :" + client.getInetAddress());
in.close();
out.close();
outMap.remove(client.getInetAddress());
inMap.remove(client.getInetAddress());
return;
}
doSomethingWithData(out, data);
}
} catch (NumberFormatException e) {
e.printStackTrace();
} catch ( Exception e ) {
e.printStackTrace();
} finally {
try {
System.out.println(client.getRemoteSocketAddress().toString() + " closing !!! ");
// remove stream handler from map
outMap.remove(client.getInetAddress());
inMap.remove(client.getInetAddress());
//close socket.
client.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
And here is client side code
public class ClientSide
{
public TcpClient client;
public String ip;
public int port;
public NetworkStream ns;
public BinaryWriter writer;
public BinaryReader reader;
public Boolean isConnected = false;
public System.Timers.Timer t;
public String lastPacketSucceeded = String.Empty;
public ClientSide(String ip, int port)
{
this.ip = ip;
this.port = port;
client = new TcpClient();
}
public bool connect()
{
try
{
client.Connect(ip, port);
}
catch (SocketException e)
{
Console.WriteLine(e.ToString());
return false;
}
Console.WriteLine("Connection Established");
reader = new BinaryReader(client.GetStream());
writer = new BinaryWriter(client.GetStream());
isConnected = true;
return true;
}
public void startListen()
{
Thread t = new Thread(new ThreadStart(listen));
t.Start();
}
public void listen()
{
byte[] buffer = new byte[4];
while (true)
{
try
{
reader.Read(buffer, 0, 4);
String len = Encoding.UTF8.GetString(buffer);
int length = Int32.Parse(len);
byte[] bodyBuf = new byte[length];
reader.Read(bodyBuf, 0, length);
String body = Encoding.UTF8.GetString(bodyBuf);
doSomethingWithBody(body);
}
catch (FormatException e)
{
Console.WriteLine(e.Message);
}
}
}
public void writeToServer(String bodyStr)
{
byte[] body = Encoding.UTF8.GetBytes(bodyStr);
int len = body.Length;
if (len > 10000)
{
Console.WriteLine("Send Abort:" + bodyStr);
}
len = len + 10000;
String lenStr = Convert.ToString(len);
lenStr = lenStr.Substring(1);
byte[] lengthHeader = Encoding.UTF8.GetBytes(lenStr);
String fullPacket = lenStr + bodyStr;
byte[] full = Encoding.UTF8.GetBytes(fullPacket);
try
{
writer.Write(full);
}
catch (Exception)
{
reader.Close();
writer.Close();
client.Close();
reader = null;
writer = null;
client = null;
Console.WriteLine("Send Fail" + fullPacket);
}
Console.WriteLine("Send complete " + fullPacket);
}
}
Considering it is impossible to recreate problem, I would guess this problem is from multithread issue. but I could not find any further clue to fix this problem.
Please let me know if you guys need any more information to solve this out.
Any help will be great appreciated, thanks in advance.
