PHP pfsockopen Function
last modified April 4, 2025
The PHP pfsockopen function opens a persistent Internet or Unix
domain socket connection. It's similar to fsockopen but maintains the
connection between requests.
Basic Definition
pfsockopen establishes a persistent socket connection to a
specified host and port. The connection remains open across multiple
script executions.
Syntax: pfsockopen(string $hostname, int $port = -1, int &$errno = null,
string &$errstr = null, float $timeout = ini_get("default_socket_timeout")).
Returns a file pointer on success, false on failure.
Basic HTTP Request
This example demonstrates making a simple HTTP GET request using pfsockopen.
<?php
declare(strict_types=1);
$fp = pfsockopen("www.example.com", 80, $errno, $errstr, 30);
if (!$fp) {
echo "Error: $errstr ($errno)";
} else {
$out = "GET / HTTP/1.1\r\n";
$out .= "Host: www.example.com\r\n";
$out .= "Connection: Close\r\n\r\n";
fwrite($fp, $out);
while (!feof($fp)) {
echo fgets($fp, 128);
}
fclose($fp);
}
This connects to example.com on port 80 and sends a basic HTTP GET request. The response is read line by line and output. The connection is persistent.
SMTP Email Sending
This example shows how to send an email through SMTP using pfsockopen.
<?php
declare(strict_types=1);
$smtp = pfsockopen("mail.example.com", 25, $errno, $errstr, 30);
if (!$smtp) {
die("Error: $errstr ($errno)");
}
function smtp_command($socket, $cmd) {
fwrite($socket, $cmd . "\r\n");
return fgets($socket, 512);
}
echo smtp_command($smtp, "EHLO localhost");
echo smtp_command($smtp, "MAIL FROM: <sender@example.com>");
echo smtp_command($smtp, "RCPT TO: <recipient@example.com>");
echo smtp_command($smtp, "DATA");
echo smtp_command($smtp, "Subject: Test\r\n\r\nHello World\r\n.");
echo smtp_command($smtp, "QUIT");
fclose($smtp);
This connects to an SMTP server and sends a basic email. The connection persists between commands. Each SMTP command gets a response from the server.
Custom TCP Server Communication
This example demonstrates communication with a custom TCP server.
<?php
declare(strict_types=1);
$socket = pfsockopen("tcp://127.0.0.1", 9000, $errno, $errstr, 30);
if (!$socket) {
die("Error: $errstr ($errno)");
}
fwrite($socket, "PING\r\n");
$response = fgets($socket, 1024);
echo "Server response: $response";
fwrite($socket, "QUIT\r\n");
fclose($socket);
This connects to a local TCP server on port 9000. It sends a PING command and reads the response. The connection remains open for subsequent requests.
HTTPS Connection with Context
This example shows how to establish a secure HTTPS connection.
<?php
declare(strict_types=1);
$context = stream_context_create([
'ssl' => [
'verify_peer' => false,
'verify_peer_name' => false
]
]);
$fp = pfsockopen('ssl://www.example.com', 443, $errno, $errstr, 30, $context);
if (!$fp) {
die("Error: $errstr ($errno)");
}
$out = "GET / HTTP/1.1\r\n";
$out .= "Host: www.example.com\r\n";
$out .= "Connection: Close\r\n\r\n";
fwrite($fp, $out);
while (!feof($fp)) {
echo fgets($fp, 128);
}
fclose($fp);
This establishes a secure HTTPS connection using SSL. The stream context allows configuration of SSL parameters. The connection persists for reuse.
Unix Domain Socket Communication
This example demonstrates communication with a Unix domain socket.
<?php
declare(strict_types=1);
$socket = pfsockopen("unix:///var/run/myservice.sock", 0, $errno, $errstr, 30);
if (!$socket) {
die("Error: $errstr ($errno)");
}
fwrite($socket, "STATUS\r\n");
$response = fgets($socket, 1024);
echo "Service status: $response";
fclose($socket);
This connects to a Unix domain socket at /var/run/myservice.sock. It sends a STATUS command and reads the response. The connection remains persistent.
Best Practices
- Error Handling: Always check for connection errors
- Timeouts: Set appropriate timeout values
- Cleanup: Close connections when done
- Security: Validate all input/output
- Performance: Reuse connections when possible
Source
This tutorial covered the PHP pfsockopen function with practical
examples for various network communication scenarios using persistent connections.