I solved my problem a few months ago. Here’s the solution I used. The standard packet-sending API (sock_create, connect, …) cannot be used in a few contexts (interruptions). Using it in the wrong place leads to a KP. The netpoll API is more “low-level” and works in every context. However, there are several conditions : … Read more
Hello from the distant future which is the year 2018, to the year 2012. There’s, in fact, a reason behind connect()ing an UDP socket in practice (though blessed POSIX and its implementations don’t in theory require you to). An ordinary UDP socket doesn’t know anything about its future destinations, so it performs a route lookup … Read more
What you are looking for can’t be done with in Javascript due to security constraints such as Distributed Denial of Service (DDOS) attacks. The closest technology available (that I know of) for client-side JS is WebRTC. With WebRTC you can use DataChannels over SRTP and ICE as a possible solution. See Also: How to send … Read more
FWIW, I did some experiments to map out the behavior of FIONREAD on different platforms. Platforms where FIONREAD returns all the data pending in a SOCK_DGRAM socket: Mac OS X, NetBSD, FreeBSD, Solaris, HP-UX, AIX, Windows Platforms where FIONREAD returns only the bytes for the first pending datagram: Linux It might also be worth noting … Read more
Yes, and no. It’s actually do-able, so long as the intervening routers don’t have no ip directed-broadcasts or similar configured. However these days that’s the default because allowing normal broadcasts to traverse routers is a DoS problem. If you really want to broadcast across subnets then you should be using IP Multicast instead. That still … Read more
It can simply be done as int PORT = 9876; UdpClient udpClient = new UdpClient(); udpClient.Client.Bind(new IPEndPoint(IPAddress.Any, PORT)); var from = new IPEndPoint(0, 0); var task = Task.Run(() => { while (true) { var recvBuffer = udpClient.Receive(ref from); Console.WriteLine(Encoding.UTF8.GetString(recvBuffer)); } }); var data = Encoding.UTF8.GetBytes(“ABCD”); udpClient.Send(data, data.Length, “255.255.255.255”, PORT); task.Wait();
You can increase the value from the default, but you can’t increase it beyond the maximum value. Use setsockopt to change the SO_RCVBUF option: int n = 1024 * 1024; if (setsockopt(socket, SOL_SOCKET, SO_RCVBUF, &n, sizeof(n)) == -1) { // deal with failure, or ignore if you can live with the default size } Note … Read more
You can bind to a port multiple times using the ReuseAddress socket option. UdpClient udpClient = new UdpClient(); udpClient.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true); You’ll need to set the same option on the UDP server socket as well.
The interface/API presented to you the user(programmer) of these protocols are: UDP Message oriented, you have an API (send/recv and similar) that provide you with the ability to send one datagram, and receive one datagram. 1 send() call results in 1 datagram sent, and 1 recv() call will recieve exactly 1 datagram. TCP Stream oriented, … Read more
UDP is actually expected to work better than TCP in lossy networks (or congested networks). TCP is far better at transferring large quantities of data, but when the network fails it’s more likely that UDP will get through. (in fact, I recently did a study testing this and it found that SNMP over UDP succeeded … Read more