Instead of having a string represent your packet length and then subtract by the string’s length to know where to start reading, you should implement proper length-prefixing. Length-prefixing combined with a data header will make you able to read every packet according to its size, then the data header will help you determine what to … Read more
What about SCTP. It’s a standard protocol by the IETF (RFC 4960) It has chunking capability which could help for speed. Update: a comparison between TCP and SCTP shows that the performances are comparable unless two interfaces can be used. Update: a nice introductory article.
First off, a “port” is just a number. All a “connection to a port” really represents is a packet which has that number specified in its “destination port” header field. Now, there are two answers to your question, one for stateful protocols and one for stateless protocols. For a stateless protocol (ie UDP), there is … Read more
In TCP there is only one way to detect an orderly disconnect, and that is by getting zero as a return value from read()/recv()/recvXXX() when reading. There is also only one reliable way to detect a broken connection: by writing to it. After enough writes to a broken connection, TCP will have done enough retries … Read more
A single listening port can accept more than one connection simultaneously. There is a ’64K’ limit that is often cited, but that is per client per server port, and needs clarifying. Each TCP/IP packet has basically four fields for addressing. These are: source_ip source_port destination_ip destination_port <—– client ——> <——— server ————> Inside the TCP … Read more
You might have guessed it already: it’s a connection error. “ECONNRESET” means the other side of the TCP conversation abruptly closed its end of the connection. This is most probably due to one or more application protocol errors. You could look at the API server logs to see if it complains about something. But since … Read more
For my suggestion, please read the last section: “When to use SO_LINGER with timeout 0”. Before we come to that a little lecture about: Normal TCP termination TIME_WAIT FIN, ACK and RST Normal TCP termination The normal TCP termination sequence looks like this (simplified): We have two peers: A and B A calls close() A … Read more
On macOS Big Sur and later, use this command: sudo lsof -i -P | grep LISTEN | grep :$PORT or to just see just IPv4: sudo lsof -nP -i4TCP:$PORT | grep LISTEN On older versions, use one of the following forms: sudo lsof -nP -iTCP:$PORT | grep LISTEN sudo lsof -nP -i:$PORT | grep LISTEN … Read more
Since there are no events available to signal when the socket is disconnected, you will have to poll it at a frequency that is acceptable to you. Using this extension method, you can have a reliable method to detect if a socket is disconnected. static class SocketExtensions { public static bool IsConnected(this Socket socket) { … Read more
The answer differs depending on what OS is being considered. In general though: For TCP, no. You can only have one application listening on the same port at one time. Now if you had 2 network cards, you could have one application listen on the first IP and the second one on the second IP … Read more