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.

http_request.php

<?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.

smtp_email.php

<?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.

custom_tcp.php

<?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.

https_connection.php

<?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.

unix_socket.php

<?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

PHP pfsockopen Documentation

This tutorial covered the PHP pfsockopen function with practical examples for various network communication scenarios using persistent connections.

Author

My name is Jan Bodnar, and I am a passionate programmer with extensive programming experience. I have been writing programming articles since 2007. To date, I have authored over 1,400 articles and 8 e-books. I possess more than ten years of experience in teaching programming.

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