mjhjmtu

I'm using busybox v1.28.1 on an embedded device (armv7l). I want to use nc to listen to TCP connections made by a javascript application (QML) on the same machine.

Here an example of the request:

function post(url, data) 
 var xhr = new XMLHttpRequest();
 var params = data;

 var timer = Qt.createQmlObject("import QtQuick 1.1; Timer interval: 50; repeat: false; running: true;", root, "TimerTimeout");

 timer.triggered.connect(function()
 xhr.abort();
 );

 xhr.onreadystatechange = function() 
 if (xhr.readyState === XMLHttpRequest.DONE) 
 timer.running = false;
 timer.destroy();
 
 ;

 xhr.open("POST", url, true);
 xhr.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
 xhr.setRequestHeader("Content-length", params.length);
 xhr.setRequestHeader("Connection", "close");
 xhr.send(params);


// ...

post("http://127.0.0.1:55764", "Hello world");

From the console I run this command:

./busybox-armv7l nc -klv -p 55764

it should listen for incoming connection on port 55764, and should stay listening for another connection after its current connection is completed.

But this is the, werid, behavior I notice:

1. 
   

   start server:

   
   
   

   ./busybox-armv7l nc -klv -p 55764
listening on [::]:55764 ...

   
   


2. 
   

   send the first packet:

   
   
   

   connect to [::ffff:127.0.0.1]:55764 from localhost.localdomain:34325 ([::ffff:127.0.0.1]:34325)

   
   

3.send another packet:

POST / HTTP/1.1
Content-Type: application/x-www-form-urlencoded;charset=UTF-8
Content-Length: 5
Connection: Keep-Alive
Accept-Encoding: gzip
Accept-Language: en,*
User-Agent: Mozilla/5.0
Host: 127.0.0.1:55764

Hello world

4. now if I send other packets no more output is shown

Why?

EDIT

I changed the code like this:

function post(url, data) 
 var xhr = new XMLHttpRequest();
 var params = data;

 var timer = Qt.createQmlObject("import QtQuick 1.1; Timer interval: 50; repeat: false; running: true;", root, "TimerTimeout");

 timer.triggered.connect(function()
 xhr.abort();
 );

 xhr.onreadystatechange = function() 
 if (xhr.readyState === XMLHttpRequest.DONE) 
 timer.running = false;
 timer.destroy();
 //console.log(xhr.responseText);
 
 ;

 xhr.open("POST", url, true);
 xhr.setRequestHeader("Content-length", params.length);
 xhr.send(params);

and the script:

#!/bin/bash
while true; do
 echo -e "HTTP/1.1 200 OKnn" | ./busybox-armv7l nc -lv -p 55764 -w 1
done

and it seems to work.
Do you see other evidence of errors?