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node.jssocketstcpbuffer

node.js: Sending and receiving bytes to a TCP socket

This should be easy to figure out but I am getting so frustrated, and I can't seem to find documentation for this rather simple case.

I want to send bytes (not strings) over a TCP connection and process a response. Here's what I've got, but it throws a type exception on the use of a Buffer type. When I use a string type instead, it sends the bytes 0xc3 0xbe 0x74 0x01 instead of 0xfe 0x74 0x01 (from tcpdump). God knows why.

If I should be using the pipe interface instead, then great, but I can't seem to find how to do so for TCP streams and not files.

const net = require ('net')

const pumpIP = '192.168.1.208'
const pumpPort = 2101
const pumpStr = '\xfe\x74\x01'
const pumpBuffer = Buffer.from(0xfe, 0x74, 0x01)


var pump = new net.Socket()

pump.connect(pumpPort, pumpIP, function() {
    pump.write(pumpBuffer)    // <-- this throws a type error
//  pump.write(pumpStr)       // <-- this sends 0xc3 0xbe 0x74 0x01 instead
})

pump.on('data', function(data) {
//  code to handle data
    pump.destroy()
})

Solution

  • For your Buffer.from(), you need to use an array. Try this:

    const pumpBuffer = Buffer.from([0xFE, 0x74, 0x01]);

    https://nodejs.org/api/buffer.html#buffer_class_method_buffer_from_array