stream_socket_client keeps sometimes truncates messages

Question

The following code should return the whole message all the time but it doesn't... I keep refreshing and at some point it prints:

Connected to UWT-RTR-002

And some others as expected:

Connected to UWT-RTR-002 Wireshark full trace start/stop control program Type "help" for instructions 2024-07-08 12:08:50 command:

Then I tried to pass the command "help" but I get nothing... It works when I use telnet on Windows Command Prompt.

UPDATE: while is taking too long, it doesn't display any error.

$address = '10.0.0.200';
$port = 41200;
$sock = stream_socket_client("tcp://".$address.":".$port, $errno, $errstr); 
fwrite($sock, "help\n");
while ($data = fread($sock, 8192)){
    echo $data."<br>";
}
fclose($sock);

Trying to read and send commands to a TCP

Answer 1

Since TCP doesn't have message boundaries, you have to define a way to tell how long the message is yourself. One option is to send the message length first, then read that many bytes in a loop.

This code will work as long as messages are less than 256 bytes long.

$address = '10.0.0.200';
$port = 41200;
$sock = stream_socket_client("tcp://".$address.":".$port, $errno, $errstr); 
$msg = "help";
fwrite($sock, chr(strlen($msg)));
fwrite($sock, $msg);
$length = ord(fread($sock, 1));
$recv_msg = '';
while ($length > 0 && $data = fread($sock, $length)){
    $recv_msg .= $data;
    $length -= strlen($data);
}
echo $recv_msg . "<br>";
fclose($sock);

Answer 2

This is what the server-guy did and it loads fast:

<?php

ini_set('display_errors', 1);
ini_set('display_startup_errors', 1);
error_reporting(E_ALL);

set_time_limit(0);
ob_implicit_flush();

$address = '10.0.0.200';
$port = 41200;
echo "<b>Address:</b> ".$address." <b>PORT</b> ".$port."\n";


$socket = stream_socket_client("tcp://".$address.":".$port,$errno, $errstr, 30);
if (!$socket)
{
    echo "error opening socket";
    die();
}

stream_socket_sendto($socket, "help\n");

$command_sent = 0;

while(!feof($socket))
{
    $data = stream_get_line($socket, 1500, "\n");
    echo $data."<br>\n";
    if ($data == 'command:')
    {
        if ($command_sent == 0)
        {
            stream_socket_sendto($socket, "status\n");
        }
        else
        {
            stream_socket_sendto($socket, "exit\n");
        }
        $command_sent = 1;
    }
}

fclose($socket);
echo "done\n";
?>