# stream_socket_client

(PHP 5)

stream_socket_client — Open Internet or Unix domain socket connection

### Description

resource stream_socket_client ( string `$remote_socket` [, int `&$errno` [, string `&$errstr` [, float `$timeout` [, int `$flags` [, resource `$context` ]]]]] )

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. The optional `timeout` can be used to set a timeout in seconds for the connect system call. `flags` is a bitmask field which may be set to any combination of connection flags. Currently the selection of connection flags is limited to `STREAM_CLIENT_CONNECT` (default), `STREAM_CLIENT_ASYNC_CONNECT` and `STREAM_CLIENT_PERSISTENT`.

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

> Note: The timeout parameter only applies if you are not making an asynchronous connection attempt.

stream_socket_client() returns a stream resource 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` and if the optional `errno` and `errstr` arguments are present they will be set to indicate 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.

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.

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

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

Example#2 Using UDP connection

`<?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);
}
?>`
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 stream_socket_server(), stream_set_blocking(), stream_set_timeout(), stream_select(), fgets(), fgetss(), fwrite(), fclose(), feof(), and the Curl extension.