PHP socket connections: read and send data in loop - php

Question

I have to make a function, in which I send a packet to server and then read data. After a while I sometimes require to send a data to server again using the same socket (it's required that I use the same one).
For some reason second send, which is after read doesn't send data (it returns correct number (not false), but server doesn't receive packet). If I create new socket and send data - it works.
Here is an example:
$socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
socket_connect($socket, '192.168.1.179', 1455);
socket_set_option($socket,SOL_SOCKET, SO_RCVTIMEO, array("sec"=>5, "usec"=>0));
$this->socket_functions->send_message($socket,$sendMsg,$funcName);
$tmp = trim($this->socket_functions->read_packet($socket));
for($i =0; $i<10; $i++)
{
$tmp = trim($this->socket_functions->read_packet($socket));
$this->socket_functions->send_message($socket, 'AAAA', $funcName); //doesn't work
/*
///works
$socket2 = $this->socket_functions->create_socket();
$this->socket_functions->send_message($socket2, 'AAAA', $funcName);
$this->socket_functions->disconnect($socket2);
*/
}
Function create_socket does the same as first 3 lines so the connection data is the same. I just brought it out so you are able to see my configuration.
For read and write I use functions socket_send() and socket_write().
Read packet function:
$resultMsg = "";
while(strlen($currentData = socket_read($socket,256))==256)
{
$resultMsg .=$currentData;
}
$resultMsg.=$currentData;
if(strlen($resultMsg)>1 && strpos($resultMsg,'<')>0)
{
$resultMsg = substr($resultMsg,strpos($resultMsg,'<'));
}
return $resultMsg;
Sending packet:
function create_packet($msg, $type)
{
$msg = $type.$this->convert_data->IntToAsciiChars(strlen($msg)).$msg;
$msg = chr(0).$this->convert_data->IntToAsciiChars(strlen($msg)).$msg;
return $msg;
}
function send_message($socket,$msg,$type)
{
$packet = $this->create_packet($msg,$type);
$res = socket_send($socket,$packet,strlen($packet),0);
if($res === false) return false;
return true;
}
EDIT
I did more testing and found out, that this only occurs, if the server, to which I'm connected keeps sending data. As in - the server sends multiple packets in row. If I try to send packet before the server has sent all of them, the packet isn't received. Does anyone knows why is this happening? I have desktop application, which does the same thing (sends data using the same socket while server is sending data), but it works there. Is there something specific?

Answer 1

I finally managed to fix this. After testing I found out, if I used send n+1 times to send the message, where n is amount of times read was called , I was able to send a message then.
I really don't know why this worked - maybe someone here knows?