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I'm trying to set up a communication via socket between a PHP page (client) and a Python script (server). The PHP page has a button that, when clicked, sends "next" to the server. This part works but the problem happens when I refresh the page. In this situation I'm not writing anything to the server, yet, the function recv() of my server seems to receive something (an empty string) because the next lines are executed. Can someone tell me what's going on ?

client.php

<?php

$host    = '127.0.0.1';
$port    = 5353;

$socket = socket_create(AF_INET, SOCK_STREAM, 0) or die('Could not create socket\n');
$result = socket_connect($socket, $host, $port) or die('Could not connect to server\n');

if(isset($_POST['btnNext'])) {
    $msg_to_server = 'next';
    socket_write($socket, $msg_to_server, strlen($msg_to_server)) or die('Could not send data to server\n');
    $msg_from_server = socket_read($socket, 1024) or die('Could not read server response\n');
    echo 'Server said : ' . $msg_from_server;
}

?>

<form action='' method='POST' >
    <button name='btnNext' type='submit'>Next</button>
</form>

server.py

import socket

host = '127.0.0.1'
port = 5353

server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server_socket.bind((host, port))
server_socket.listen(5)

while True:
    client_socket, addr = server_socket.accept()
    # doesn't wait for the client response :
    msg_from_client = client_socket.recv(5000).decode()
    print('Client said : ' + msg_from_client)
Raphaël Goisque
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1 Answers1

1

change your php part to this.

<?php

$host    = '127.0.0.1';
$port    = 5357;

if(isset($_POST['btnNext'])) {

$socket = socket_create(AF_INET, SOCK_STREAM, 0) or die('Could not create socket\n');
$result = socket_connect($socket, $host, $port) or die('Could not connect to server\n');
//creating socket connection under condition o.w making those empty str
$msg_to_server = 'next';
socket_write($socket, $msg_to_server, strlen($msg_to_server)) or die('Could not send data to server\n');
$msg_from_server = socket_read($socket, 1024) or die('Could not read server response\n');
echo 'Server said : ' . $msg_from_server;
   socket_close($socket); //probably ?
}

?>
Amin S
  • 546
  • 1
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  • This works but it is still weird behavior. It seems that either the recv() function doesn't wait for a reponse, or socket_connect() acts like socket_write() and sends an empty string . Thank you. – Raphaël Goisque Feb 04 '23 at 23:17
  • well i guess you are trying with many requests. check this out https://stackoverflow.com/questions/23828264/how-to-make-a-simple-multithreaded-socket-server-in-python-that-remembers-client – Amin S Feb 04 '23 at 23:45