socket_recv

Receives data from a connected socket

&reftitle.description; `int` `socket_recv` `resource` `socket` `string` `buf` `int` `len` `int` `flags`

The `socket_recv` function receives `len` bytes of data in `buf` from `socket`. `socket_recv` can be used to gather data from connected sockets. Additionally, one or more flags can be specified to modify the behaviour of the function.

`buf` is passed by reference, so it must be specified as a variable in the argument list. Data read from `socket` by `socket_recv` will be returned in `buf`.

&reftitle.parameters;

`socket`

- The `socket` must be a socket resource previously created by socket_create().

`buf`

- The data received will be fetched to the variable specified with `buf`. If an error occurs, if the connection is reset, or if no data is available, `buf` will be set to &null;.

`len`

- Up to `len` bytes will be fetched from remote host.

`flags`

- The value of `flags` can be any combination of the following flags, joined with the binary OR (`|`) operator.

  ## Possible values for `flags`

  Flag | Description
  `MSG_OOB` | Process out-of-band data.
  `MSG_PEEK` | Receive data from the beginning of the receive queue without removing it from the queue.
  `MSG_WAITALL` | Block until at least `len` are received. However, if a signal is caught or the remote host disconnects, the function may return less data.
  `MSG_DONTWAIT` | With this flag set, the function returns even if it would normally have blocked.

&reftitle.returnvalues;

`socket_recv` returns the number of bytes received, or &false; if there was an error. The actual error code can be retrieved by calling `socket_last_error`. This error code may be passed to `socket_strerror` to get a textual explanation of the error.

&reftitle.examples;

### `socket_recv` example

This example is a simple rewrite of the first example from sockets.examples to use `socket_recv`.

    <?php
    error_reporting(E_ALL);

    echo "<h2>TCP/IP Connection</h2>\n";

    /* Get the port for the WWW service. */
    $service_port = getservbyname('www', 'tcp');

    /* Get the IP address for the target host. */
    $address = gethostbyname('www.example.com');

    /* Create a TCP/IP socket. */
    $socket = socket_create(AF_INET, SOCK_STREAM, SOL_TCP);
    if ($socket === false) {
        echo "socket_create() failed: reason: " . socket_strerror(socket_last_error()) . "\n";
    } else {
        echo "OK.\n";
    }

    echo "Attempting to connect to '$address' on port '$service_port'...";
    $result = socket_connect($socket, $address, $service_port);
    if ($result === false) {
        echo "socket_connect() failed.\nReason: ($result) " . socket_strerror(socket_last_error($socket)) . "\n";
    } else {
        echo "OK.\n";
    }

    $in = "HEAD / HTTP/1.1\r\n";
    $in .= "Host: www.example.com\r\n";
    $in .= "Connection: Close\r\n\r\n";
    $out = '';

    echo "Sending HTTP HEAD request...";
    socket_write($socket, $in, strlen($in));
    echo "OK.\n";

    echo "Reading response:\n\n";
    $buf = 'This is my buffer.';
    if (false !== ($bytes = socket_recv($socket, $buf, 2048, MSG_WAITALL))) {
        echo "Read $bytes bytes from socket_recv(). Closing socket...";
    } else {
        echo "socket_recv() failed; reason: " . socket_strerror(socket_last_error($socket)) . "\n";
    }
    socket_close($socket);

    echo $buf . "\n";
    echo "OK.\n\n";
    ?>

The above example will produce something like:

    <h2>TCP/IP Connection</h2>
    OK.
    Attempting to connect to '208.77.188.166' on port '80'...OK.
    Sending HTTP HEAD request...OK.
    Reading response:

    Read 123 bytes from socket_recv(). Closing socket...HTTP/1.1 200 OK
    Date: Mon, 14 Sep 2009 08:56:36 GMT
    Server: Apache/2.2.3 (Red Hat)
    Last-Modified: Tue, 15 Nov 2005 13:24:10 GMT
    ETag: "b80f4-1b6-80bfd280"
    Accept-Ranges: bytes
    Content-Length: 438
    Connection: close
    Content-Type: text/html; charset=UTF-8

    OK.