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Checking who is listening on a Unix Domain Socket
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FSOCKOPEN(3) 1 FSOCKOPEN(3) fsockopen - Open Internet or Unix domain socket connection SYNOPSIS
resource fsockopen (string $hostname, [int $port = -1], [int &$errno], [string &$errstr], [float $timeout = ini_get("default_socket_timeout")]) DESCRIPTION
Initiates a socket connection to the resource specified by $hostname. PHP supports targets in the Internet and Unix domains as described in "List of Supported Socket Transports". A list of supported trans- ports can also be retrieved using stream_get_transports(3). The socket will by default be opened in blocking mode. You can switch it to non-blocking mode by using stream_set_blocking(3). The function stream_socket_client(3) is similar but provides a richer set of options, including non-blocking connection and the ability to provide a stream context. PARAMETERS
o $hostname - If OpenSSL support is installed, you may prefix the $hostname with either ssl:// or tls:// to use an SSL or TLS client connec- tion over TCP/IP to connect to the remote host. o $port - The port number. This can be omitted and skipped with -1 for transports that do not use ports, such as unix://. o $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. o $errstr - The error message as a string. o $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(3), as the $timeout parameter to fsockopen(3) only applies while connecting the socket. RETURN VALUES
fsockopen(3) returns a file pointer which may be used together with the other file functions (such as fgets(3), fgetss(3), fwrite(3), fclose(3), and feof(3)). If the call fails, it will return FALSE ERRORS
/EXCEPTIONS Throws E_WARNING if $hostname is not a valid domain. EXAMPLES
Example #1 fsockopen(3) Example <?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 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 - $errstr<br /> "; } else { fwrite($fp, " "); 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. Note When specifying a numerical IPv6 address (e.g. fe80::1), you must enclose the IP in square brackets--for example, tcp://[fe80::1]:80. SEE ALSO
pfsockopen(3), stream_socket_client(3), stream_set_blocking(3), stream_set_timeout(3), fgets(3), fgetss(3), fwrite(3), fclose(3), feof(3), socket_connect(3), The Curl extension. PHP Documentation Group FSOCKOPEN(3)
