Does this mean that the send() call will always return immediately if there is room in the kernel send buffer? Yes. As long as immediately means after the memory you provided it has been copied to the kernel’s buffer. Which, in some edge cases, may not be so immediate. For instance if the pointer you … Read more
Here is what I was looking for: static int FreeTcpPort() { TcpListener l = new TcpListener(IPAddress.Loopback, 0); l.Start(); int port = ((IPEndPoint)l.LocalEndpoint).Port; l.Stop(); return port; }
A connection timeout occurs only upon starting the TCP connection. This usually happens if the remote machine does not answer. This means that the server has been shut down, you used the wrong IP/DNS name, wrong port or the network connection to the server is down. A socket timeout is dedicated to monitor the continuous … Read more
In short: You should be able to achieve in the order of millions of simultaneous active TCP connections and by extension HTTP request(s). This tells you the maximum performance you can expect with the right platform with the right configuration. Today, I was worried whether IIS with ASP.NET would support in the order of 100 … Read more
This is one of my favorite questions. UDP is so misunderstood. In situations where you really want to get a simple answer to another server quickly, UDP works best. In general, you want the answer to be in one response packet, and you are prepared to implement your own protocol for reliability or to resend. … Read more
The port number is an unsigned 16-bit integer, so 65535.
How to print data from TCP packets Below is an example which does exactly what you need: hook received TCP packets and print their payloads. If you want to print some other information from received packet (like binary data), you just need to modify a bit the section under this comment: /* —– Print all … 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
Here is some code I’ve used on many Unix-like systems (e.g SunOS 4, SGI IRIX, HPUX 10.20, CentOS 5, Cygwin) to close a socket: int getSO_ERROR(int fd) { int err = 1; socklen_t len = sizeof err; if (-1 == getsockopt(fd, SOL_SOCKET, SO_ERROR, (char *)&err, &len)) FatalError(“getSO_ERROR”); if (err) errno = err; // set errno … Read more
It must be async, there is no way around this. High performance and scalability don’t mix with one-thread-per-socket. You can have a look at what StackExchange themselves are doing, see async Redis await BookSleeve which leverages the CTP features from the next C# release (so is on the edge and subject to changes, but it … Read more