Receive and send msgs from C client to nodejs server

Question

I have made a TCP client in C, and Im looking to make the server side in nodejs for simplicity and for easy integration into a existing app...

Well in my C code I receive and send msgs in the next way:

numBytes = send( sock, &timeStamp, sizeof( timeStamp ), 0 );
if( numBytes < 0 )
    DieWithSystemMessage( "send( ) failed" );

After reading a little about the "net" and "socket.io" packages for nodejs I haven't found the way to make it work... I apologize if this is somethog simple but it is my first time working with nodejs. If you have some blog or github link that have made something similar I will be glad to take a look, Thanks!!!

Answer 1

You need to use the net module, so a simple TCP listener would look something like:

const
   port = 1234,
   net = require('net');
server = net.createServer(function(connection) {
            connection.write("Welcome to my server"); });
server.listen(port, function() { 
            console.log("Listening..."); });

See Node.js net API for further details

Basically, node works with callbacks due to its asynchronous nature, so if you want to register a callback for a 'message' event on the socket, like that:

server.on('data', function(data) { 
    console.log('Received data');
    /* Do manipulations on the inbound data */
});

So there you define a callback to be executed on a 'data' event, so whenever you receive data on the socket, the anonymus function defined in the on() call will be executed.

Answer 2

Node.JS is very usable for such an application (I started the exact same project a month ago and I didn't have any regrets that I chose Node.JS at all). Here an example code of a Node.JS server:

const port = 46500;
var net = require('net');
var server = net.createServer(function(connection) {
    console.log('client connected');

    connection.on('close', function (){
        console.log('client disconnected');
     });

    connection.on('data', function (data) {
        data = data.toString();
        console.log('client sended the folowing string:'+data);
        connection.write("Response");
        console.log('Sended responst to client');
        connection.end();
        console.log('Disconnected the client.');
   });

});


server.listen(port, function () {
    console.log('server is listening');
}); 

I saw a comment of you in another post where I can't response (due to less than 50 reputation) but you can hard code the ip address of the Node.JS server inside of your c code (but make sure you have a backup option for when the ip of the server changes) or you can implement a DNS client inside of the c application if the server has a domain name.

Answer 3

您可以使用argv传递ip，也可以使用像Hxd这样的十六进制编辑器进行修改。