PHP: TCP sockets, 'unable to bind address' - php

Question

i've seen other people with this problem, but maybe i can explain my situation and you can point out where the issue might be.
im getting a 'Warning : socket_bind(): unable to bind address [98]: Address already in use' error.
the situation is this. I am using a web application to trigger another program to perform tasks (from a webpage interface). The results of that program are sent through a socket to my web application that is listening on a socket.
first i create and open the socket, then i trigger the other program, then when that program is finished it should send its results back through the socket.
it works fine the first try. Then the next try (i trigger this process many times) i get the above socket bind error when trying to open the socket, obviously the socket is still bound.
i wait about a minute and i can successfully run the process again. I think the socket connection timesout.
I dont know if the problem is because of the way i have structure my socket code, or if the problem is in the external program that i am triggering. I dont know much about the internals of the external program as its a jar file built by someone else.
heres the code i use for creating and handling the socket. I just used an example on php.net and altered it for my needs.
$port1 = 15000;
// configure the socket
error_reporting(E_ALL);
set_time_limit(0);
ob_implicit_flush();
$address = '127.0.0.1';
$port2 = 54321;
$sock = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
$error = 'none';
if ($sock) {
if (socket_bind($sock, $address, $port2)) {
if (socket_listen($sock, 5)) {
// trigger external process
if (start_calibration()) {
$buf = array();
// listen to the socket for incoming messages
do {
// if incomming connection is not accepted break out and close socket
if (($msgsock = socket_accept($sock)) === false) {
break;
}
do {
// if cant read socket then break out and close socket
if (false === ($buf = socket_read($msgsock, 2048, PHP_BINARY_READ))) {
break 2;
}
$buf = unpack('C*', $buf);
socket_close($msgsock);
break 2;
} while (true);
socket_close($msgsock);
} while (true);
socket_close($sock);
// code to handle data recieved through the socket
}
else {
// start_calibration failed
$error = 'start_calibration failed';
socket_close($sock);
}
}
else {
// socket_listen failed
$error = 'socket_listen failed';
socket_close($sock);
}
}
else {
// socket_bind failed
$error = 'socket_bind failed';
socket_close($sock);
}
}
else {
// socket_create failed
$error = 'socket_create failed';
}
$data['error'] = $error;
echo json_encode($data);
also, is there is a more efficient way to handle the closing of sockets if there is problems with lines like 'socket_bind', 'socket_listen' etc?

Answer 1

Did you try to set the flag SO_REUSEADDR on your socket?
There's a sample in the socket_set_option's documentation.