PHP fsockopen() Function: Usage, Parameters, and Examples

The PHP fsockopen() function opens a network or Unix socket connection, returning a file handle that can be used with standard file functions.

Signature:

resource fsockopen(string $hostname [, int $port = -1 [, int &$errno [, string &$errstr [, float $timeout = ini_get("default_socket_timeout")]]]])

.

It initializes a socket to the specified host; if OpenSSL is available, the hostname may be prefixed with ssl:// or tls://. The default mode is blocking, but stream_set_blocking() can change it. stream_socket_client() offers similar functionality with more options.

Parameters:

hostname : target host, optionally prefixed with ssl:// or tls:// for encrypted connections.

port : port number; -1 indicates no port (e.g., unix://).

errno : optional variable that receives the system error number if the connection fails before the socket is created.

errstr : optional variable that receives the error message string.

timeout : optional timeout in seconds, defaulting to the default_socket_timeout ini setting.

Return value: on success, a file handle resource; on failure, FALSE.

Example 1 – HTTP GET request

<?php
$fp = fsockopen("www.example.com", 80, $errno, $errstr, 30);
if (!$fp) {
    echo "$errstr ($errno)<br />
";
} else {
    $out = "GET / HTTP/1.1
";
    $out .= "Host: www.example.com
";
    $out .= "Connection: Close

";
    fwrite($fp, $out);
    while (!feof($fp)) {
        echo fgets($fp, 128);
    }
    fclose($fp);
}
?>

Example 2 – UDP socket

<?php
$fp = fsockopen("udp://127.0.0.1", 13, $errno, $errstr);
if (!$fp) {
    echo "ERROR: $errno - $errstr<br />
";
} else {
    fwrite($fp, "
");
    echo fread($fp, 26);
    fclose($fp);
}
?>