I have a server and a client that communicate with each other over an UDP socket. The server are opening port 10002 and are listening for incoming datagrams.
For the client to get the server ip it sends one broadcast datagram which the server responds to. The client code responsible for finding the ip address of the server looks like this:
private IPEndPoint GetServerEP(TimeSpan timeout, UdpClient udpclient)
{
IPEndpoint server = new IPEndPoint(IPAddress.Broadcast, 10002);
byte[] data = GetDiscoverDatagram();
_udpclient.EnableBroadcast = true;
udpclient.Send(data, data.Length, server);
try
{
udpclient.Client.ReceiveTimeout = (int)timeout.TotalMilliseconds;
udpclient.Receive(ref server);
}
catch (SocketException e)
{
string msg = string.Format("Server did not respond within {0} ms", timeout.TotalMilliseconds);
throw new TimeoutException(msg, e);
}
return server;
}
Upon running this, I can see that the server actually receives the broadcast datagram and responds with a packet bound for the same port as the client sends from. However, the client does not receive anything and timeouts.
What am I missing?
Stupid me (or; stupid firewall). The code worked, but the firewall blocked the response packet from the server. After disabling everything works like a charm.
Related
I'm trying to use MQTTNet as service broker, that takes requests from webClients over MQTT.js. However, this method is notworking for unknown reasons.
when i test the Service Broker using the windows application "MQTT Explorer" as a client, it works fine.
When i test the MQTT.js Client to connect to an open Service Broker like broker.emqx.io it works also fine.
but the connection between my service Broker with the mqtt client has always a problem. The following error is thrown from the MQTTNet Server:
Client '[::1]:58434' accepted by TCP listener '[::]:8883, ipv6'.
Expected at least 21538 bytes but there are only 69 bytes
MQTTnet.Exceptions.MqttProtocolViolationException: Expected at least 21538 bytes but there are
only 69 bytes
at MQTTnet.Formatter.MqttBufferReader.ReadString()
at MQTTnet.Formatter.MqttPacketFormatterAdapter.ParseProtocolVersion(ReceivedMqttPacket
receivedMqttPacket)
at MQTTnet.Formatter.MqttPacketFormatterAdapter.DetectProtocolVersion(ReceivedMqttPacket
receivedMqttPacket)
at MQTTnet.Adapter.MqttChannelAdapter.ReceivePacketAsync(CancellationToken cancellationToken)
at MQTTnet.Server.MqttClientSessionsManager.ReceiveConnectPacket(IMqttChannelAdapter
channelAdapter, CancellationToken cancellationToken)
at MQTTnet.Server.MqttClientSessionsManager.HandleClientConnectionAsync(IMqttChannelAdapter
channelAdapter, CancellationToken cancellationToken)
Client '[::1]:58434' disconnected at TCP listener '[::]:8883, ipv6'.
configuration of my server are as following:
static async Task<MqttServer> StartMqttServer(bool isDevelopment, ConsoleLogger consoleLogger = null)
{
MqttFactory mqttFactory = new MqttFactory();
if (consoleLogger != null)
{
mqttFactory = new MqttFactory(consoleLogger);
}
// Due to security reasons the "default" endpoint (which is unencrypted) is not enabled by default!
var mqttServerOptions = mqttFactory.CreateServerOptionsBuilder()
.WithDefaultEndpoint()
.Build();
var server = mqttFactory.CreateMqttServer(mqttServerOptions);
await server.StartAsync();
return server;
}
does anybody know why is this happening? And perhaps have an idea how i can fix it?
Thanks in advaced.
org.apache.ignite.internal.util.nio.GridNioServer#createSelector
// Create a new selector
selector = SelectorProvider.provider().openSelector();
if (addr != null) {
// Create a new non-blocking server socket channel
srvrCh = ServerSocketChannel.open();
srvrCh.configureBlocking(false);
if (sockRcvBuf > 0)
srvrCh.socket().setReceiveBufferSize(sockRcvBuf);
// Bind the server socket to the specified address and port
srvrCh.socket().bind(addr);
// Register the server socket channel, indicating an interest in
// accepting new connections
srvrCh.register(selector, SelectionKey.OP_ACCEPT);
}
return selector;
Why is the Ignite port listening not authenticated?
How can I set authentication?
Two parts:
It has to open the connection so that it can be told what the credentials are. If they're not valid, Ignite will disconnect
Ignite can only authenticate thin-clients out-of-the-box. I have not checked the code, but this could be a server or thick-client code path
We are using spring integration application for data receiption from gps devices. For current configuration we are able to receive data from device also respose sent back to device through same connection
current configuration is as
#SpringBootApplication
#IntegrationComponentScan
public class SpringIntegrationApplication extends SpringBootServletInitializer{
private Integer TIMEOUT=1000*60*10;
#Value("${TCP_PORT}")
private Integer TCP_PORT;
public static void main(String[] args) throws IOException {
ConfigurableApplicationContext ctx = SpringApplication.run(SpringIntegrationApplication.class, args);
System.in.read();
ctx.close();
}
#Bean
TcpNetServerConnectionFactory cf(){
TcpNetServerConnectionFactory connectionFactory=new TcpNetServerConnectionFactory(TCP_PORT);
connectionFactory.setSerializer(new CustomSerializerDeserializer());
connectionFactory.setDeserializer(new CustomSerializerDeserializer());
connectionFactory.setSoTimeout(TIMEOUT);
return connectionFactory;
}
#Bean
TcpInboundGateway tcpGate(){
TcpInboundGateway gateway=new TcpInboundGateway();
gateway.setConnectionFactory(cf());
gateway.setRequestChannel(requestChannel());
gateway.setRequestTimeout(TIMEOUT);
return gateway;
}
#Bean
public MessageChannel requestChannel(){
return new DirectChannel();
}
}
and message end point
#MessageEndpoint
public class Echo {
#ServiceActivator(inputChannel="requestChannel")
public byte[] echo(byte[] in,#SuppressWarnings("deprecation") #Header("ip_address") String ip){
//here we receive packet data in bytes from gps device
return "".getBytes();//string will contains expected result for device.
}
Above configuartion works fine for one way communication. but we want to implement two way communication. What we want after connection established between server and device we want to send message explicitely.To send command through server we dont know ip and port of device, so how can we send command through server to connected device.
I am trying following solution
created oubound channel adapter
#Bean
public TcpSendingMessageHandler tcpSendingMessageHandler() {
System.out.println("Creating outbound adapter");
TcpSendingMessageHandler outbound = new TcpSendingMessageHandler();
return outbound;
}
then created gateway for explicite message send, this will be called from service where we want to send data explicitely
#MessagingGateway(defaultRequestChannel="toTcp")
public static interface tcpSendService {
public byte [] send(String string);
}
After calling gate way following service activator invoked where we are setting connection ip and port, these ip and ports will be from connection established while receiving data from device
#ServiceActivator(inputChannel="toTcp", outputChannel="fromTcp")
public String send(String in){
System.out.println(new String(in));
TcpNetClientConnectionFactory factory = new TcpNetClientConnectionFactory(ip_extracted_from_inbound_connection, port_extarcted_from_inbound_connection);
factory.start();
tcpSendingMessageHandler.setConnectionFactory(factory);
return in;
}
// for ip and port extraction i am using following service which is inbound sevice
#ServiceActivator(inputChannel="requestChannel")
public byte[] echo(byte[] in,#Header("ip_address") String ip){
System.out.println(new String(in)+ " ; IP : "+ip);
for (String connectionId : factory.getOpenConnectionIds()) {
if(!lastConection.contains(ip))
lastConection = connectionId;
}
return "hello".getBytes();
}
For service activator i am setting new TcpNetClientConnectionFactory every time service called. Ip and port are extracted from TcpNetServerConnectionFactory. whenever device connects with server i am saving its connection ip and port, using these ip and port for data transmission through server but i am getting connection timeout issue.
Kindly help me out and suggest me a solution over it.
Thank you.
Replace the gateway with a pair of Collaborating Outbound and Inbound Channel Adapters.
In order to send arbitrary messages to a connection, you must set the ip_connectionId header.
The challenge, though, is how to direct the reply to the gateway. You would need to capture the replyChannel header from the request and, when a reply is received for that ip_connectionId, set the replyChannel headers.
This will only work, though, if you have only one request/reply outstanding to each device at a time, unless there is some data in the reply that can be used to correlate it to a request.
Another challenge is race conditions, where the device and the server initiate a request at the same time. You would need to look at data in the inbound message to see if it's a request or reply.
I am trying to connect to a remote external server using TCP sockets in WCF code
My WCF service is the client which has code using sockets to connect to an external server.
This code sends a request to an external server and receives the server response
int byteCount = 0;
Socket m_socClient;
try
{
string query = "My Request String";
m_socClient = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
System.Net.IPAddress remoteIPAddress = System.Net.IPAddress.Parse("127:0:0:0");
System.Net.IPEndPoint remoteEndPoint = new System.Net.IPEndPoint(remoteIPAddress, 1234);
EVCommon.Log("COnnecting to" + IPSelected + Port);
m_socClient.Connect(remoteEndPoint);
try
{
if (m_socClient.Connected)
{
EVCommon.Log("Connected to" + IPSelected + Port);
var reQuestToSend = string.Format("POST /ZZZZZ HTTP/1.1\r\nContent-Length:{0}\r\n\r\n{1}", query.Length, query);
byte[] bytesToSend = Encoding.ASCII.GetBytes(reQuestToSend);
byteCount = m_socClient.Send(bytesToSend, SocketFlags.None);
byte[] bytesReceived = new byte[1024];
byteCount = m_socClient.Receive(bytesReceived, SocketFlags.None);
Response271 = Encoding.ASCII.GetString(bytesReceived);
m_socClient.Disconnect(false);
m_socClient.Close(5000);
}
}
catch(Exception ex)
{
EVCommon.Log(ex.Message);
}
}
If I make a windows application with the same client code to connect to the remote server, it is successful. I am able to connect, send and receive
This error occurs only when I bring WCF into the picture. The code fails at if(m_socket.Connected). So it is not able to connect successfully.
A request to send or receive data was disallowed because the socket
is not connected and (when sending on a datagram socket using a sendto call) no address was supplied.
Thank you
The difference is that the windows applications runs in the identity of the logged in user and the WCF service runs in the identity of the application pool.
What is probably happening is that the application pool is running as NETWORK SERVICE which does not have the right to open a port.
Try changing the identity of the app pool to your user to check if this is the problem.
I have a locally hosted WCF service and a silverlight 5 app that communicates with it. By default silverlight tries to obtain the cross domain policy file over HTTP when making calls to the WCF service. I need to change this so that the policy file is served over net.tcp port 943 instead.
I have setup a local tcp listener that serves up the policy file over port 943 and i have followed this technique whereby i make a dummy socket connection in order to obtain the policy file over tcp as it is only retrieved once per application lifetime. The tcp server is being hit as expected and i am getting SocketError property value as Success (though i must note, the first time i hit the tcp server after starting the listener, the result is always access denied).
From what i can tell, the policy file is either invalid as the silverlight application as still unable to connect or the above mentioned technique does not work with silverlight 5.
What i would like to know is if what i am doing is possible & im doing it correctly, otherwise if there is an alternative means to have the policy file successfully downloaded over tcp and removing the need for retrieving it over HTTP.
Thanks
I wrote a long post about hosting silverlight in WPF - and using WCF with a http listener here:
How can I host a Silverlight 4 application in a WPF 4 application?
Now while not directly answering your question, it does show how to create a http version of the policy file.
I have also written something that serves up a policy listener over port 943, but I can't find where I posted the source - so I'll keep digging. As far as I remember though, silverlight does a cascade find of the policy file, if it doesn't get a connection on port 80, it'll then look on port 943.
I hope this is of some help somewhere.
Ok, here is the policy listener I had for net.TCP transport i.e. not HTTP based. I presume you have sorted this by now, sorry for the delay. It may well be of use to someone else now.
I was looking for the MS thing that said they cascade from HTTP to TCP, however, I can't, and therefore have to assume it was bunk and then changed.
Either way, if you call using a net.TCP service, and want a listener for it, this code should help:
#region "Policy Listener"
// This is a simple policy listener
// that provides the cross domain policy file for silverlight applications
// this provides them with a network access policy
public class SocketPolicyListener
{
private TcpListener listener = null;
private TcpClient Client = null;
byte[] Data;
private NetworkStream netStream = null;
private string listenaddress = "";
// This could be read from a file on the disk, but for now, this gives the silverlight application
// the ability to access any domain, and all the silverlight ports 4502-4534
string policyfile = "<?xml version='1.0' encoding='utf-8'?><access-policy><cross-domain-access><policy><allow-from><domain uri='*' /></allow-from><grant-to><socket-resource port='4502-4534' protocol='tcp' /></grant-to></policy></cross-domain-access></access-policy>";
// the request that we're expecting from the client
private string _policyRequestString = "<policy-file-request/>";
// Listen for our clients to connect
public void Listen(string ListenIPAddress)
{
listenaddress = ListenIPAddress;
if (listener == null)
{
listener = new TcpListener(IPAddress.Parse(ListenIPAddress), 943);
// Try and stop our clients from lingering, keeping the socket open:
LingerOption lo = new LingerOption(true, 1);
listener.Server.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.Linger,lo);
}
listener.Start();
WaitForClientConnect();
}
private void WaitForClientConnect()
{
listener.BeginAcceptTcpClient(new AsyncCallback(OnClientConnected), listener);
}
public void StopPolicyListener()
{
if (Client.Connected)
{
// Should never reach this point, as clients
// are closed if they request the policy
// only clients that open the connection and
// do not submit a policy request will remain unclosed
Client.Close();
}
listener.Stop();
}
public void RestartPolicyListener()
{
listener.Start();
}
// When a client connects:
private void OnClientConnected(IAsyncResult ar)
{
if (ar.IsCompleted)
{
// Get the listener that handles the client request.
TcpListener listener = (TcpListener)ar.AsyncState;
// End the operation and display the received data on
// the console.
Client = listener.EndAcceptTcpClient(ar);
// Try and stop our clients from lingering, keeping the socket open:
LingerOption lo = new LingerOption(true, 1);
Client.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.Linger, lo);
// Set our receive callback
Data = new byte[1024];
netStream = Client.GetStream();
netStream.BeginRead(Data, 0, 1024, ReceiveMessage, null);
}
WaitForClientConnect();
}
// Read from clients.
public void ReceiveMessage(IAsyncResult ar)
{
int bufferLength;
try
{
bufferLength = Client.GetStream().EndRead(ar);
// Receive the message from client side.
string messageReceived = Encoding.ASCII.GetString(Data, 0, bufferLength);
if (messageReceived == _policyRequestString)
{
// Send our policy file, as it's been requested
SendMessage(policyfile);
// Have to close the connection or the
// silverlight client will wait around.
Client.Close();
}
else
{
// Continue reading from client.
Client.GetStream().BeginRead(Data, 0, Data.Length, ReceiveMessage, null);
}
}
catch (Exception ex)
{
throw new Exception(Client.Client.RemoteEndPoint.ToString() + " is disconnected.");
}
}
// Send the message.
public void SendMessage(string message)
{
try
{
byte[] bytesToSend = System.Text.Encoding.ASCII.GetBytes(message);
//Client.Client.Send(bytesToSend,SocketFlags.None);
Client.GetStream().Write(bytesToSend,0, bytesToSend.Length);
Client.GetStream().Flush();
}
catch (Exception ex)
{
throw ex;
}
}
}
#endregion