I developed simple async server that listens to unix socket and sync client that send the some small piece of data. Time between moment when i send data from client to the moment when server receives them is completly random, from 1 to 9 seconds. I wonder why is the reason? Server is implemented as shown in msdn example here (using beginReceive): http://msdn.microsoft.com/en-us/library/fx6588te.aspx
EndPoint ep = new UnixEndPoint(_fileName);
_socket = new Socket(AddressFamily.Unix, SocketType.Stream, ProtocolType.IP);
try
{
_socket.Bind(ep);
_socket.Listen(_maxConnectionsInQuee);
while(true)
{
done.Reset();
_socket.BeginAccept(new AsyncCallback(AcceptCallback), null);
done.WaitOne();
}
}
And in the client:
EndPoint ep = new UnixEndPoint(_fileName);
_socket = new Socket(AddressFamily.Unix, SocketType.Stream, ProtocolType.IP);
_socket.Connect(ep);
byte[] bytes = Encoding.UTF8.GetBytes(message);
_socket.Send(bytes);
Method that sends data to the server is called from webservice method (running via xsp2).
It occures that unix sockets in mono are ok :). I had some threading issues which were completely unrelated to Mono.Unix and unix domain sockets. Thanks all for your help.
Related
I'm trying to make two applications. One will be sending data to a specific udp port, and the other will be reading it.
I am having 2 problems:
when running on the same machine, I get an error: "Only one usage
of each socket address (protocol/network address/port) is normally
permitted" so I need to figure out how to test it if I cannot have
multiple socket connections at the same port.
when I tried using
an internal ip of another computer within my network, I did not get
any reading at all.
server:
private Socket sock;
private const int PORT = 5000;
public void start()
{
sock = new Socket(AddressFamily.InterNetwork, SocketType.Dgram, ProtocolType.Udp);
sock.ReceiveTimeout = 1;// seconds
sock.SendTimeout = 1;// seconds
IPEndPoint iep = new IPEndPoint(IPAddress.Any, PORT);
EndPoint ep = (EndPoint)iep;
sock.Bind(iep);
MulticastView view_obj = new MulticastView();
while(true)
{
try
{
if (sock.Connected)
{
sock.Send(Serializer.ObjectToByteArray(view_obj));
}
}catch(Exception ex){
Console.WriteLine(ex);
}
Thread.Sleep(1000); // milliseconds
}
}
client:
IPAddress ip = IPAddress.Parse("127.0.0.1");
IPEndPoint iep = new IPEndPoint(ip, PORT);
EndPoint ep = (EndPoint)iep;
UdpClient client = new UdpClient(PORT);
IPEndPoint RemoteIpEndPoint = new IPEndPoint(IPAddress.Any, 0);
// or using: Byte[] receiveBytes = client.Receive(ref ep);
Byte[] receiveBytes = client.Receive(ref RemoteIpEndPoint);
MulticastView view;
view = (MulticastView)Serializer.ByteArrayToObject(receiveBytes);
Note that I need separate apps (on separate processes).
You can't have 2 separate sockets open on the same IP address / port. Each IP/Port is a unique mailbox, so to speak. (Technically, it is possible to have 2 processes attached to the same socket, under certain circumstances, but that isn't relevant to your problem). The rule is simple, but the workarounds are several.
I would ask if the client really needs to have a standard port number. Normally, UDP/TCP clients just use a random socket and communicate with the server. The server is usually the only side of the connection that needs a standard, fixed port. The UdpClient.Receive() method will populate the IPEndPoint with the ip/port of the sender of the packet so that you can reply to it.
Either don't bind to IPAddress.Any (that causes it to bind to all interfaces). Replace the Any with a specific IP address (one machine can have multiple if you setup IP aliasing or multiple adapters), or simpler, change the port number of the client to differ from the server. You should be able to bind one end to the primary ethernet interface IP address, and bind the client to the loopback (127.0.0.1) address.
Even though this is an old question, I think it would be good to point out an exception to the one port rule.
If you are using multicast (which is UDP to a multicast address), you can set the SO_REUSEADDR option to use the port for multiple sockets.
I have a problem with 2 uwp apps : one client and one server to communicate.
I have a textbox and a button on each.
The server side is like this :
listenerSocket = new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
IPEndPoint ipEnd = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 8888);
listenerSocket.NoDelay = true;
listenerSocket.Bind(ipEnd);
listenerSocket.Listen(0);
and on ButtonClick
Socket clientSocket = listenerSocket.Accept();
Byte[] Buffer = new byte[clientSocket.SendBufferSize];
int readByte = clientSocket.Receive(Buffer);
txtEvents.Text = readByte.ToString();
On the client side is like this
client= new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
IPEndPoint ipEnd = new IPEndPoint(IPAddress.Parse("127.0.0.1"), 8888);
and on buttonClick_Event
client.Connect(ipEnd);
client.Send(System.Text.Encoding.UTF8.GetBytes("Hey");
But nothing is happen.
Thanks for your help
best regards
As the document Note part:
As a consequence of network isolation, Windows disallows
establishing a socket connection (Sockets or WinSock) between two UWP
apps running on the same machine; whether that's via the local
loopback address (127.0.0.0), or by explicitly specifying the local IP
address.
You can try to test your socket on two devices which deploy the client and server respectively.
Besides, you can also enable loopback for network access and troubleshoot network isolation issues, please see the How to enable loopback and troubleshoot network isolation topic to get details.
I try to modify my code with this sample :
https://social.msdn.microsoft.com/Forums/vstudio/en-US/3f4d435b-48c8-4b5f-9c5c-8ba1166fd808/uwpctcp-socket-server-using-ipendpoint-uwp?forum=wpdevelop
That's help me with the Accept(); hangs on my app but now on my server side i try to see the text send by client with this line
private void RecieveArg_Completed(object sender, SocketAsyncEventArgs e)
{
byte[] recBuf = new byte[e.BytesTransferred];
Array.Copy(buffer, recBuf, e.BytesTransferred);
string ReceivedText = Encoding.ASCII.GetString(recBuf);
txt_Events.Text = ReceivedText;
Client_Socket.ReceiveAsync(RecieveArg);
}
but nothing appear on my server txt_Events box. I know that the client is connecting because the server is closing.
Thanks for your help.
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
In .NET CF on a Windows CE 5.0 based POS device, if no connection (GPRS/WiFi) is available, when i try to connect my socket object i don't get any exceptions, even after it, when i try to send bytes to somewhere by Socket.SentTo() method i don't get any exceptions too! And even the returned value indicating the size of totally sent bytes is correct! what's the matter? how can i ensure of the health of the operations?
pieces of my code:
Socket m_socClient = new Socket(
AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp);
IPAddress ipAdd = IPAddress.Parse("192.168.7.80");
IPEndPoint remoteEP = new IPEndPoint(ipAdd, 2415);
m_socClient.Connect(remoteEP); // No exception!
// why works?
int iSent = m_socClient.SendTo(byData, byData.Length,
SocketFlags.None, remoteEP);
Few suggestions:
Check the Connected property of the connection
I understand SendTo is more suited for connectionless protocols, and Send() is better suited for Connection-oriented protocols like TCP.
Send() (and I expect SendTo()) may have no effect if there is no data to send. Have you checked there is data?
Overview: I have set up a server and a client, where both attempt discovery of each other using UDP. When the server starts up it sends a multicast message (239.1.1.1) that it is alive. When the client starts up it sends a multicast message (239.1.1.2) that it is alive. Both server and client are subscribed to each other's multicast messages to receive their transmissions. This way, regardless of which application (server or client) starts up first, one or the other will be notified of their existence.
On the client side I do the following:
Set up a listening socket to subscribe to and receive server originated multicast messages.
Set up a receiving socket to receive server responses to client's multicast
message per #3 below.
Send a muticast message (for server to receive and respond to) that client is running.
Receive server response to clients multicast message sent in #3.
Question: Everything is working fine, except that both receiving sockets end up getting the server's (non-multicast) response to the client. I am not clear if this is expected behavior or not. Can I reduce the two receiving sockets to one? #1 is subscribed to the server's multicast and #2 is simply listening for a direct transmission from the server on the same port (non-multicast message from server). Can I safely remove the second receiving socket?
See source code below (I removed exception handling for simpler code presentation).
Client code:
// 1. Set up a socket and asynchronously listen for server startup multicasts.
Socket listenSocket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram,
ProtocolType.Udp);
listenSocket.SetSocketOption(SocketOptionLevel.Socket,
SocketOptionName.ReuseAddress, 1);
listenSocket.Bind(new IPEndPoint(IPAddress.Any, 50000));
listenSocket.SetSocketOption(SocketOptionLevel.IP,SocketOptionName.AddMembership,
new MulticastOption(IPAddress.Parse("239.1.1.1")));
EndPoint clientEndPoint = new IPEndPoint(0, 0);
listenSocket.BeginReceiveFrom(receiveBuffer, 0, receiveBuffer.Length,
SocketFlags.None, ref clientEndPoint,
new AsyncCallback(OnServerMessageReceived), (object)this);
// 2. Set up socket to receive the server's response to client's multicast.
Socket receiveSocket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram,
ProtocolType.Udp);
receiveSocket.SetSocketOption(SocketOptionLevel.Socket,
SocketOptionName.ReuseAddress, 1);
receiveSocket.Bind(new IPEndPoint(IPAddress.Any, 50000));
receiveSocket.ReceiveTimeout = 3000; // Timeout after 3 seconds.
// 3. Send a multicast message for server to respond to.
Socket sendSocket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram,
ProtocolType.Udp);
EndPoint multicastEndPoint = new IPEndPoint(IPAddress.Parse("239.1.1.2"), 50000);
sendSocket.SendTo(packet, packet.Length, SocketFlags.None, multicastEndPoint);
// 4. Wait for server to respond to the multicast message (timeout = 3 seconds).
byte[] receiveBuff = new byte[2048];
EndPoint serverEndPoint = new IPEndPoint(0, 0);
int bytesRead = receiveSocket.ReceiveFrom(receiveBuff, ref serverEndPoint);
Server code:
// Receive multicast message sent from client (in asynchronous callback method).
EndPoint clientEndPoint = new IPEndPoint(0, 0);
int bytesRead = listenSocket.EndReceiveFrom(asyncResult, ref clientEndPoint);
// Send response back to the client (change port to 50000).
EndPoint destination = new IPEndPoint((clientEndPoint as IPEndPoint).Address,
50000);
Socket responseSocket = new Socket(AddressFamily.InterNetwork, SocketType.Dgram,
ProtocolType.Udp);
responseSocket.SendTo(response, response.Length, SocketFlags.None, destination);
The answer to your question is "Yes, this is expected behaviour". You don't need to open a seperate socket to recieve unicast packets on the same port.
PS
It seems like overkill to have your servers join a multicast group to listen for new clients - you could just have the servers regularly transmit a beacon to the client multicast address saying "I am here" (say, once every 30 seconds).
receiveSocket.Bind(new IPEndPoint(IPAddress.Any, 50000));
Your receive sockets are binding to ANY address, which means they will receive unicast, broadcast and multicast traffic. You can bind to an interface address to just receive unicast traffic, and you can bind just to the multicast group to only receive multicast traffic.
When sending a UDP datagram you can specify the destination address which may be multicast or unicast. You can therefore reduce both the server and client code to one socket each.
Whilst I'm not sure it's addressing your issue, I would expect both client and server to talk on the same IP multicast address (e.g. 239.1.1.1). At the moment it looks like you've given the client and server one address each, and what happens if/when you introduce a new client ?
Better option would be to use a service discovery protocol like Bonjour or Avahi than rolling your own, as they have solved a lot of problems already.