(PHP 5, PHP 7)
stream_socket_client — Open Internet or Unix domain socket connection
$remote_socket
[, int &$errno
[, string &$errstr
[, float $timeout = ini_get("default_socket_timeout")
[, int $flags = STREAM_CLIENT_CONNECT
[, resource $context
]]]]] ) : resource
Initiates a stream or datagram connection to the destination specified
by remote_socket. The type of socket created
is determined by the transport specified using standard URL formatting:
transport://target. For Internet Domain sockets
(AF_INET) such as TCP and UDP, the target portion
of the remote_socket parameter should consist of
a hostname or IP address followed by a colon and a port number. For Unix
domain sockets, the target portion should point
to the socket file on the filesystem.
Note:
The stream will by default be opened in blocking mode. You can switch it to non-blocking mode by using stream_set_blocking().
remote_socketAddress to the socket to connect to.
errnoWill be set to the system level error number if connection fails.
errstrWill be set to the system level error message if the connection fails.
timeoutNumber of seconds until the connect() system call should timeout.
Note: This parameter only applies when not making asynchronous connection attempts.
Note:
To set a timeout for reading/writing data over the socket, use the stream_set_timeout(), as the
timeoutonly applies while making connecting the socket.
flags
Bitmask field which may be set to any combination of connection flags.
Currently the select of connection flags is limited to
STREAM_CLIENT_CONNECT (default),
STREAM_CLIENT_ASYNC_CONNECT and
STREAM_CLIENT_PERSISTENT.
contextA valid context resource created with stream_context_create().
On success a stream resource is returned which may
be used together with the other file functions (such as
fgets(), fgetss(),
fwrite(), fclose(), and
feof()), FALSE on failure.
On failure the errno and
errstr arguments will be populated with the actual
system level error 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. Note that
the errno and
errstr arguments will always be passed by
reference.
Example #1 stream_socket_client() example
<?php
$fp = stream_socket_client("tcp://www.example.com:80", $errno, $errstr, 30);
if (!$fp) {
echo "$errstr ($errno)<br />\n";
} else {
fwrite($fp, "GET / HTTP/1.0\r\nHost: www.example.com\r\nAccept: */*\r\n\r\n");
while (!feof($fp)) {
echo fgets($fp, 1024);
}
fclose($fp);
}
?>
Example #2 Using UDP connection
Retrieving the day and time from the UDP service "daytime" (port 13) on localhost.
<?php
$fp = stream_socket_client("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);
}
?>
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.
Note:
Depending on the environment, the Unix domain or the optional connect timeout may not be available. A list of available transports can be retrieved using stream_get_transports(). See List of Supported Socket Transports for a list of built in transports.