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PHP supports targets in the Internet and Unix domains as described in List of Supported Socket Transports. A list of supported transports can also be retrieved using stream_get_transports().

The socket will by default be opened in blocking mode. You can switch it to non-blocking mode by using stream_set_blocking().

Parameters

hostname

If you have compiled in OpenSSL support, you may prefix the hostname with either ssl:// or tls:// to use an SSL or TLS client connection over TCP/IP to connect to the remote host.

port

The port number.

errno

If provided, holds the system level error number that occurred in the system-level connect() call.

If the value returned in errno is 0 and the function returned FALSE, it is an indication that the error occurred before the connect() call. This is most likely due to a problem initializing the socket.

errstr

The error message as a string.

timeout

The connection timeout, in seconds.

Note: If you need to set a timeout for reading/writing data over the socket, use stream_set_timeout(), as the timeout parameter to fsockopen() only applies while connecting the socket.

Return Values

fsockopen() returns a file pointer which may be used together with the other file functions (such as fgets(), fgetss(), fwrite(), fclose(), and feof()). If the call fails, it will return FALSE

ChangeLog

Version	Description
4.3.0	Added support for the `timeout` parameter on win32.
4.3.0	SSL and TLS over TCP/IP support was added.
4.0.0	UDP support was added.
3.0.9	The `timeout` parameter was added.

Examples

Example #1 fsockopen() Example


<?php
$fp = fsockopen("www.example.com", 80, $errno, $errstr, 30);
if (!$fp) {
    echo "$errstr ($errno)<br />\n";
} 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);
}
?>

Example #2 Using UDP connection

The example below shows how to retrieve the day and time from the UDP service "daytime" (port 13) in your own machine.


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

Notes

Note: Depending on the environment, the Unix domain or the optional connect timeout may not be available.

Warning

UDP sockets will sometimes appear to have opened without an error, even if the remote host is unreachable. The error will only become apparent when you read or write data to/from the socket. The reason for this is because UDP is a "connectionless" protocol, which means that the operating system does not try to establish a link for the socket until it actually needs to send or receive data.