I have a server which works fine. But I think the way I am passing strings from a server to client is not the right way.
This is my current approach in server.
foreach (Socket _connectedUsers in clientSockets)
{
byte[] data = Encoding.UTF32.GetBytes("Text");
Socket socket = (Socket)_connectedUsers;
socket.Send(data);
}
In this approach it is sending string to all connected clients. But I want to be able to specify particular socket and send it to one unique connected client.
I know that I can identify IP and PORT of any connected socket by using this function:
IPEndPoint remoteIpEndPoint = current.RemoteEndPoint as IPEndPoint;
This function allows me to see what IP and port number current socket has.
But lets say I get entire list of connected sockets and get them as 'IPEndPoint' list. How can I convert it into socket to do something like this?
IPEndPoint remoteIpEndPoint = current.RemoteEndPoint as IPEndPoint;
Socket SendToSocket = remoteIpEndPoint as Socket; //I know this is wrong.. How can I convert it to socket?
byte[] data = Encoding.ASCII.GetBytes("Server can Hear you");
SendToSocket.Send(data);
How can I convert IPEndPoint or string with IP and Port or anything else into Socket?
I think I explained my question in very detail.
If you have any other suggestions or techniques how I could make this possible, please help. :)
Also it is worth to mention why I don't want to use 'foreach', because if I will stream my web camera in my app, I don't want to stream to everyone because 'foreach' is streaming for everyone. This is why I need to specify unique socket to avoid streaming and reduce traffic in other clients when they are not supposed to receive anything.
Related
I want to learn about socket communication so I decided to try to write WP 8.1 text communicator. It is based on TCP sockets. I almost managed to finish it, but I am searching for improvemenets.
What is worth mentioning I use a socket server between phones (console application), to avoid problems with private ip addresses. It contains information about all connected users and forwards messages to clients (for instance user A sends message to user B, so firstly message goes to server and server forward it to destination address).
The problem appeared when i realized that I need to send special messages from server to client and vice versa (for example when two clients want to have conversation, they send request to server, so it knows where to forward messages).
This is my connection listener method from server application
private void ConnectionListener()
{
IPEndPoint localDataEndPoint = new IPEndPoint(IPAddress.Parse(LocalIpAddress), 1234);
IPEndPoint localMessageEndPoint = new IPEndPoint(IPAddress.Parse(LocalIpAddress), 4321);
Socket dataConnectionListener = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
Socket messageConnectionListener = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
try
{
dataConnectionListener.Bind(localDataEndPoint);
dataConnectionListener.Listen(100);
messageConnectionListener.Bind(localMessageEndPoint);
messageConnectionListener.Listen(100);
while (true)
{
TcpSocket.clientDone.Reset();
IAsyncResult tmp1 = dataConnectionListener.BeginAccept(ConnectionCallback, null);
IAsyncResult tmp2 = messageConnectionListener.BeginAccept(ConnectionCallback, null);
TcpSocket.clientDone.WaitOne();
Socket dataSocket = dataConnectionListener.EndAccept(tmp1);
Socket messageSocket = messageConnectionListener.EndAccept(tmp2);
TcpSocket tmpTcpSocket = new TcpSocket(dataSocket, messageSocket);
tmpTcpSocket.Start();
connectedUsersSockets.Add(tmpTcpSocket);
UpdateConnectedUserList();
}
}
catch (Exception ex)
{
Log.E("Connection listener ran into an exception", ex);
}
}
As you can see I have created two TCP sockets to liesten on different ports. dataSocket is for normal messages and messageSocket is for special messages (sorry for confusing names, I have to refractor code).
On client side it works the same way: there are two different socket to communicate with and through the server.
I wanted to avoid managing two sockets rather then one. But the only way I can imagine is that on every received message server would have to check if it's special (and handle it in special way) or just send to client.
The question: Is there a better way to manage these special messages?
Thanks to all in advance!
P.S.
Sorry for my poor english, it's not my native language
I been reading a lot on how to implement UDP hole punching but fore some reason I cannot make it work.
For those that are not familiar of what udp hole punching is here is my own definition:
The goal is to be able to transfer data between two clients (Client A
and client B) with the help of a server. So client A connects to the server and sends its info. Client B does the same. The server has the nessesary info so that Client A is able to send data to Client B and vise versa . Therefore the server gives that info to both clients. Once both clients have that info about each other it is possible to start sending and receiving data between those clients without the help of the server.
My goal is to be able to do what I just described (udp hole punching). Before doing so I think it will be helpful to be able to connect from the server to the client. In order to do so I plan to send the server the info about the client. Once the server receives that info attempt to connect to the client from scratch. Once I am able to perform that I should have everything I need to start implementing the real udp hole punching.
Here is how I have things set up:
The top router has the server and bottom router connected to LAN ports. The bottom router (NAT) is connected to the top router via it's WAN port. And the client computer is connected to the bottom router to one of its LAN ports.
So in that connection the client is able to see the server but the server is not able to see the client.
So the algorithm I have done in pseudo code is:
Client connects to server.
Client send some UDP packages to the server in order to open some ports on the NAT
Send information to the server on what ports the client is listening to.
Once the server receives that info attempt to connect to the client from scratch.
Here is the implementation in code:
Server:
static void Main()
{
/* Part 1 receive data from client */
UdpClient listener = new UdpClient(11000);
IPEndPoint groupEP = new IPEndPoint(IPAddress.Any, 11000);
string received_data;
byte[] receive_byte_array = listener.Receive(ref groupEP);
received_data = Encoding.ASCII.GetString(receive_byte_array, 0, receive_byte_array.Length);
// get info
var ip = groupEP.Address.ToString();
var port = groupEP.Port;
/* Part 2 atempt to connect to client from scratch */
// now atempt to send data to client from scratch once we have the info
Socket sendSocket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
IPEndPoint endPointClient = new IPEndPoint(IPAddress.Parse(ip), port);
sendSocket.SendTo(Encoding.ASCII.GetBytes("Hello"), endPointClient);
}
Client:
static void Main(string[] args)
{
/* Part 1 send info to server */
Socket sending_socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
IPAddress send_to_address = IPAddress.Parse("192.168.0.132");
IPEndPoint sending_end_point = new IPEndPoint(send_to_address, 11000);
sending_socket.SendTo(Encoding.ASCII.GetBytes("Test"), sending_end_point);
// get info
var port = sending_socket.LocalEndPoint.ToString().Split(':')[1];
/* Part 2 receive data from server */
IPEndPoint groupEP = new IPEndPoint(IPAddress.Any, int.Parse(port));
byte[] buffer = new byte[1024];
sending_socket.Receive(buffer);
}
For some reason it worked a few times! It works when the client receives data successfully on the line: sending_socket.Receive(buffer);
Things to note:
If on the server on the second part I used the instance variable listner instead of creating the new variable sendSocket and send the bytes through that variable the client is able to receive the data being sent. Remember that the second part of the server is going to be implemented by a second client B that's why I am initializing variables again from scratch...
Edit:
Here is a different way of looking at the same problem. When I initialize a new object instead of using the same object the client does not receives the response.
I have a object of type UdpClient. I am able to send data with that object to the other peer. If I create another object of the same type with the same properties and attempt to send data it does not work! I might be missing to initialize some variables. I am able to set private variables with reflection so I should not have a problem. anyways here is the server code:
public static void Main()
{
// wait for client to send data
UdpClient listener = new UdpClient(11000);
IPEndPoint groupEP = new IPEndPoint(IPAddress.Any, 11000);
byte[] receive_byte_array = listener.Receive(ref groupEP);
// connect so that we are able to send data back
listener.Connect(groupEP);
byte[] dataToSend = new byte[] { 1, 2, 3, 4, 5 };
// now let's atempt to reply back
// this part does not work!
UdpClient newClient = CopyUdpClient(listener, groupEP);
newClient.Send(dataToSend, dataToSend.Length);
// this part works!
listener.Send(dataToSend, dataToSend.Length);
}
static UdpClient CopyUdpClient(UdpClient client, IPEndPoint groupEP)
{
var ip = groupEP.Address.ToString();
var port = groupEP.Port;
var newUdpClient = new UdpClient(ip, port);
return newUdpClient;
}
the client code basically sends data to the server and then waits for a response:
string ipOfServer = "192.168.0.132";
int portServerIsListeningOn = 11000;
// send data to server
Socket sending_socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
IPAddress send_to_address = IPAddress.Parse(ipOfServer);
IPEndPoint sending_end_point = new IPEndPoint(send_to_address, portServerIsListeningOn);
sending_socket.SendTo(Encoding.ASCII.GetBytes("Test"), sending_end_point);
// get info
var port = sending_socket.LocalEndPoint.ToString().Split(':')[1];
// now wait for server to send data back
IPEndPoint groupEP = new IPEndPoint(IPAddress.Any, int.Parse(port));
byte[] buffer = new byte[1024];
sending_socket.Receive(buffer); // <----- keeps waiting in here :(
note that the client is behind a router (NAT) otherwise I will not have this problem. The reason why I will like to copy udpClient is so that I can send that variable to another computer enabling the other computer to send data to the client.
So my question is why is the original object listener able to send data but newClient is not able to? The client keeps waiting at line sending_socket.Receive(buffer); even after the server executes the line: newClient.Send(dataToSend, dataToSend.Length);. the client successfully receives data when listener sends the data but not newClient. Why is this if both variables have the same destination IP and port? how do the variables differ?
Note:
If the server and client are on the same network then the copy works and variable newClient is able to send data to the client. To simulate this problem the client must be behind a NAT (router). An example of such network may consist of two routers. let's call them router X and router Y. You also need a Server call that S. and a client C. so S can be connected to one of the LAN ports of X. C can be connected to one of the LAN ports of Y. Finally connect the WAN port of Y to one of the LAN ports of X.
Hmm, I think you are confusing several things here. For one thing, it's really called UDP hole punching. Let me try to explain how this should work.
NAT routers usually do port mapping when forwarding packets from the inside private network to the outside internet.
Say you created a UDP socket on a machine behind NAT, and sent a datagram to some external IP/port. When the IP packet carrying that datagram leaves the sending machine, its IP header has the source address field set to local not-globally-routable private IP address (like 192.168.1.15), and UDP header has the source port field set to whatever port was assigned to the socket (either explicitly via binding, or implicitly picked by the OS from the ephemeral ports). I'll call this source port number P1.
Then when the NAT router sends that packet out on the outside network, it overwrites the source IP address to its own external IP address (otherwise there's no way to route packets back), and often overwrites the source UDP port to some other value (maybe because some other host on the private network uses the same source port, which creates ambiguity). The mapping between the original source port and that new port number (let's label it P2) is preserved in the router to match return packets. This mapping might also be specific to the target IP address and target UDP port.
So now you have "punched a hole" in the router - UDP packets sent back to the router to port P2 are forwarded to internal machine on UDP port P1. Again, depending on NAT implementation, this could be restricted to only packets from the original target IP address and target UDP port.
For client-to-client communication you'll have to tell external IP/port of one to the other through the server, hoping that the NAT router maps same internal source ports to same external source ports. Then the clients will send packets to each other using those.
Hope this helps.
Finally found the answer! Here is the implemenation with just a client and a server. My next attempt will be to use 3 computers. anyways hope this helps:
Server code:
class Program
{
static byte[] dataToSend = new byte[] { 1, 2, 3, 4, 5 };
// get the ip and port number where the client will be listening on
static IPEndPoint GetClientInfo()
{
// wait for client to send data
using (UdpClient listener = new UdpClient(11000))
{
IPEndPoint groupEP = new IPEndPoint(IPAddress.Any, 11000);
byte[] receive_byte_array = listener.Receive(ref groupEP);
return groupEP;
}
}
static void Main(string[] args)
{
var info = GetClientInfo(); // get client info
/* NOW THAT WE HAVE THE INFO FROM THE CLIENT WE ARE GONG TO SEND
DATA TO IT FROM SCRATCH!. NOTE THE CLIENT IS BEHIND A NAT AND
WE WILL STILL BE ABLE TO SEND PACKAGES TO IT
*/
// create a new client. this client will be created on a
// different computer when I do readl udp punch holing
UdpClient newClient = ConstructUdpClient(info);
// send data
newClient.Send(dataToSend, dataToSend.Length);
}
// Construct a socket with the info received from the client
static UdpClient ConstructUdpClient(IPEndPoint clientInfo)
{
var ip = clientInfo.Address.ToString();
var port = clientInfo.Port;
// this is the part I was missing!!!!
// the local end point must match. this should be the ip this computer is listening on
// and also the port
UdpClient client = new UdpClient(new IPEndPoint( IPAddress.Any, 11000));
// lastly we are missing to set the end points. (ip and port client is listening on)
// the connect method sets the remote endpoints
client.Connect(ip, port);
return client;
}
}
client code:
string ipOfServer = "192.168.0.139";
int portServerIsListeningOn = 11000;
// send data to server
Socket sending_socket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
IPAddress send_to_address = IPAddress.Parse(ipOfServer);
IPEndPoint sending_end_point = new IPEndPoint(send_to_address, portServerIsListeningOn);
sending_socket.SendTo(Encoding.ASCII.GetBytes("Test"), sending_end_point);
// get info
var port = sending_socket.LocalEndPoint.ToString().Split(':')[1];
// now wait for server to send data back
IPEndPoint groupEP = new IPEndPoint(IPAddress.Any, int.Parse(port));
byte[] buffer = new byte[1024];
sending_socket.Receive(buffer); // <----- we can receive data now!!!!!
Have you considered using UPnP on the client to configure NAT traversal to allow incoming packets on a particular port? The client would then only need to communicate the inbound IP and port to the server, and wait for the server to send packets.
http://en.wikipedia.org/wiki/Universal_Plug_and_Play
Seems you are able to connect with the server first time.After successful connection you need to close and disconnect the connection each time.Please check this sample code
http://codeidol.com/csharp/csharp-network/Connectionless-Sockets/A-Simple-UDP-Application/
I am just learing about networking and I belive there's something called "dynamic ports".
I can't get my head around that, how would I implement a server, that uses dynamic ports? When setting up a socket, I'll have to bind to a specific port just like:
using (Socket socket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp))
{
IPEndPoint endPoint = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 1234);
socket.Bind(endPoint);
socket.Listen(10);
using (Socket handler = socket.Accept())
{
/* ... */
}
}
I needed to definly set the port I wantet to listen on (1234).
As far as I understand dynamic ports, a client sends a request to a random port and the server somehow dermines which application will get those request and make a response.
How would the client say
I would like my request to be responded my the "MyCustomService01" application?
Can someone please clarify and give some sample code?
socket is your listener, that despatches onto ephemeral ports; if you look carefully at handler, in particular at .LocalEndPoint and .RemoteEndPoint, you should find it is already configured as a dynamic port. Basically, you shouldn't have to do anything special here - just communicate via handler.
I read 2 C# chat source code & I see a problem:
One source uses Socket class:
private void StartToListen(object sender , DoWorkEventArgs e)
{
this.listenerSocket = new Socket(AddressFamily.InterNetwork , SocketType.Stream , ProtocolType.Tcp);
this.listenerSocket.Bind(new IPEndPoint(this.serverIP , this.serverPort));
this.listenerSocket.Listen(200);
while ( true )
this.CreateNewClientManager(this.listenerSocket.Accept());
}
And other one uses TcpListener class:
server = new TcpListener(portNumber);
logger.Info("Server starts");
while (true)
{
server.Start();
if (server.Pending())
{
TcpClient connection = server.AcceptTcpClient();
logger.Info("Connection made");
BackForth BF = new BackForth(connection);
}
}
Please help me to choose the one. I should use Socket class or TcpListener class. Socket connection is TCP or UDP? Thanks.
UDP is connectionless, but can have a fake connection enforced at both ends on the socket objects. TCP is a stream protocol (what you send will be received in chunks on the other end), and additionally creates endpoint sockets for each accepted socket connection (the main listening socket is left untouched, although you'd probably need to call listen() again). UDP uses datagrams, chunks of data which are received whole on the other side (unless the size is bigger than the MTU, but that's a different story).
It looks to me like these two pieces of code are both using TCP, and so as the underlying protocol is the same, they should be completely compatible with each other. It looks as if you should use the second bit of code since it's higher level, but only the server can really use this, the client needs a different bit of code since it doesn't listen, it connects... If you can find the 'connecting' code at the same level of abstraction, use that.
In c# I am using the UdpClient.Receive function:
public void StartUdpListener(Object state)
{
try
{
udpServer = new UdpClient(new IPEndPoint(IPAddress.Broadcast, 1234));
}
catch (SocketException ex)
{
MessageBox.Show(ex.ErrorCode.ToString());
}
IPEndPoint remoteEndPoint = null;
receivedNotification=udpServer.Receive(ref remoteEndPoint);
...
However I am getting a socket exception saying that the address is not available with error code 10049
What do I do to negate this exception?
Here's the jist of some code I am currently using in a production app that works (we've got a bit extra in there to handle the case where the client are server apps are running on a standalone installation). It's job is to receive udp notifications that messages are ready for processing. As mentioned by Adam Alexander your only problem is that you need to use IPAddress.Any, instead of IPAddress.Broadcast. You would only use IPAddress.Broadcast when you wanted to Send a broadcast UDP packet.
Set up the udp client
this.broadcastAddress = new IPEndPoint(IPAddress.Any, 1234);
this.udpClient = new UdpClient();
this.udpClient.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
this.udpClient.ExclusiveAddressUse = false; // only if you want to send/receive on same machine.
And to trigger the start of an async receive using a callback.
this.udpClient.Client.Bind(this.broadcastAddress);
this.udpClient.BeginReceive(new AsyncCallback(this.ReceiveCallback), null);
Hopefully this helps, you should be able to adapt it to working synchronously without too much issue. Very similar to what you are doing. If you're still getting the error after this then something else must be using the port that you are trying to listen on.
So, to clarify.
IPAddress.Any = Used to receive. I want to listen for a packet arriving on any IP Address.
IPAddress.Broadcast = Used to send. I want to send a packet to anyone who is listening.
for your purposes I believe you will want to use IPAddress.Any instead of IPAddress.Broadcast. Hope this helps!
That error means the protocol cant bind to the selected IP/port combination.
I havent used UDP broadcast in ages, but I do recall you need to use different IP ranges.
There's nothing wrong with the way you have configured your UdpClient. Have you tried a different port number? Perhaps 1234 is already in use on your system by a different app.