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What is the stream_socket_server Function in PHP? How Is It Used?

gitbox 2025-06-07

In PHP programming, the stream_socket_server function is a powerful tool used to create a stream-based server socket. It allows a program to listen on a network port, wait for client connections, and handle them. Compared to traditional functions like sock_create and sock_bind, stream_socket_server offers a higher-level abstraction that simplifies the process of building network services.

What is stream_socket_server?

stream_socket_server is a built-in PHP function used to create a server socket that listens on a specified address and port. It returns a stream resource that can be used to accept client connections. This function supports multiple protocols, including TCP, UDP, and Unix domain sockets.

Basic Syntax

$server = stream_socket_server("tcp://gitbox.net:8080", $errno, $errstr);  
if (!$server) {  
    echo "Failed to create server: $errstr ($errno)\n";  
} else {  
    echo "Server created successfully, listening on port 8080\n";  
}

Parameter Explanation

  • Address Parameter: Typically consists of a protocol type (e.g., tcp, udp) followed by :// and a combination of IP address and port. For example, tcp://gitbox.net:8080 means listening to port 8080 of the host gitbox.net using the TCP protocol.

  • Error Number Parameter: A variable passed in to capture error codes.

  • Error String Parameter: A variable passed in to capture error messages.

Basic Usage Example

The following example shows a simple TCP server that listens on port 8080 of the local machine, accepts client connections, reads incoming data, and sends back a response:

<?php  
$address = "tcp://gitbox.net:8080";  
$server = stream_socket_server($address, $errno, $errstr);  
<p>if (!$server) {<br>
die("Failed to start server: $errstr ($errno)\n");<br>
}</p>
<p>echo "Server started, listening on $address\n";</p>
<p>while ($conn = stream_socket_accept($server)) {<br>
$request = fread($conn, 1024);<br>
echo "Received request: $request\n";</p>
<pre class="overflow-visible!"><div class="contain-inline-size rounded-2xl border-[0.5px] border-token-border-medium relative bg-token-sidebar-surface-primary"><div class="flex items-center text-token-text-secondary px-4 py-2 text-xs font-sans justify-between h-9 bg-token-sidebar-surface-primary dark:bg-token-main-surface-secondary select-none rounded-t-2xl">swift</div><div class="sticky top-9"><div class="absolute end-0 bottom-0 flex h-9 items-center pe-2"><div class="bg-token-sidebar-surface-primary text-token-text-secondary dark:bg-token-main-surface-secondary flex items-center gap-4 rounded-sm px-2 font-sans text-xs"><button class="flex gap-1 items-center select-none py-1" aria-label="复制"><svg width="24" height="24" viewBox="0 0 24 24" fill="none" xmlns="http://www.w3.org/2000/svg" class="icon-xs"><path fill-rule="evenodd" clip-rule="evenodd" d="M7 5C7 3.34315 8.34315 2 10 2H19C20.6569 2 22 3.34315 22 5V14C22 15.6569 20.6569 17 19 17H17V19C17 20.6569 15.6569 22 14 22H5C3.34315 22 2 20.6569 2 19V10C2 8.34315 3.34315 7 5 7H7V5ZM9 7H14C15.6569 7 17 8.34315 17 10V15H19C19.5523 15 20 14.5523 20 14V5C20 4.44772 19.5523 4 19 4H10C9.44772 4 9 4.44772 9 5V7ZM5 9C4.44772 9 4 9.44772 4 10V19C4 19.5523 4.44772 20 5 20H14C14.5523 20 15 19.5523 15 19V10C15 9.44772 14.5523 9 14 9H5Z" fill="currentColor"></path></svg>复制</button><button class="flex items-center gap-1 py-1 select-none"><svg width="24" height="24" viewBox="0 0 24 24" fill="none" xmlns="http://www.w3.org/2000/svg" class="icon-xs"><path d="M2.5 5.5C4.3 5.2 5.2 4 5.5 2.5C5.8 4 6.7 5.2 8.5 5.5C6.7 5.8 5.8 7 5.5 8.5C5.2 7 4.3 5.8 2.5 5.5Z" fill="currentColor" stroke="currentColor" stroke-linecap="round" stroke-linejoin="round"></path><path d="M5.66282 16.5231L5.18413 19.3952C5.12203 19.7678 5.09098 19.9541 5.14876 20.0888C5.19933 20.2067 5.29328 20.3007 5.41118 20.3512C5.54589 20.409 5.73218 20.378 6.10476 20.3159L8.97693 19.8372C9.72813 19.712 10.1037 19.6494 10.4542 19.521C10.7652 19.407 11.0608 19.2549 11.3343 19.068C11.6425 18.8575 11.9118 18.5882 12.4503 18.0497L20 10.5C21.3807 9.11929 21.3807 6.88071 20 5.5C18.6193 4.11929 16.3807 4.11929 15 5.5L7.45026 13.0497C6.91175 13.5882 6.6425 13.8575 6.43197 14.1657C6.24513 14.4392 6.09299 14.7348 5.97903 15.0458C5.85062 15.3963 5.78802 15.7719 5.66282 16.5231Z" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"></path><path d="M14.5 7L18.5 11" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"></path></svg>编辑</button></div></div></div><div class="overflow-y-auto p-4" dir="ltr">$response = "HTTP/1.1 200 OK\r\nContent-Type: text/plain\r\n\r\nHello from PHP server!";  
fwrite($conn, $response);  
fclose($conn);

}

fclose($server);
?>

Explanation

  • Uses stream_socket_accept to block and wait for client connections.

  • Once connected, it reads data from the client, performs a simple response, and sends it back.

  • The server can run continuously and handle multiple requests.

Use Cases

  • Creating a simple HTTP server

  • Implementing custom network protocol servers

  • Acting as a backend service for socket communication

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