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    stream_socket_recvfrom

    (PHP 5, PHP 7, PHP 8)

    stream_socket_recvfrom — Recibir información de un socket, conectado o no

    Descripción

    stream_socket_recvfrom(
        resource $socket,
        int $length,
        int $flags = 0,
        string &$address = ?
    ): string

    stream_socket_recvfrom() acepta información desde un socket remoto hasta length bytes.

    Parámetros

    socket

    El socket remoto.

    length

    El número de bytes a recibir desde el socket.

    flags

    El valor de flags puede ser una combinación de los siguientes valores:

    Valores posibles para flags
    STREAM_OOB Procesar información OOB (out-of-band, fuera de banda).
    STREAM_PEEK Recuperar información del socket, pero sin consumir el buffer. Las llamadas subsiguientes a fread() o stream_socket_recvfrom() verán la misma información.

    address

    Si se proporciona address, será rellenado con la dirección de socket remoto.

    Valores devueltos

    Devuelve la información leída, como cadena

    Ejemplos

    Ejemplo #1 Ejemplo de stream_socket_recvfrom()

    <?php
    /* Abrir un socket de servidor al puerto 1234 en localhost */
    $server = stream_socket_server('tcp://127.0.0.1:1234');

    /* Aceptar una conexión */
    $socket = stream_socket_accept($server);

    /* Tomar un paquete (1500 es un tamaño de MTU típico) de información OOB */
    echo "Recibido Fuera de Banda: '" . stream_socket_recvfrom($socket, 1500, STREAM_OOB) . "'\n";

    /* Echar un vistazo a la información en banda normal, pero sin comsumirla. */
    echo "Información: '" . stream_socket_recvfrom($socket, 1500, STREAM_PEEK) . "'\n";

    /* Obtener el mismo paquete exactamente otra vez, pero eliminándolo del buffer esta vez. */
    echo "Información: '" . stream_socket_recvfrom($socket, 1500) . "'\n";

    /* Cerrarlo */
    fclose($socket);
    fclose($server);
    ?>

    Notas

    Nota:

    Si un mensaje recibido es mayor que el parámetro length, los bytes en exceso se pueden desechar dependiendo del tipo de socket desde el que se recbió el mensaje (como UDP).

    Nota:

    Las llamadas a stream_socket_recvfrom() sobre flujos basados en sockets, después de las llamadas a funciones de flujos basados en buffer (como fread() o stream_get_line()), leen información directamente desde el socket y evitan el buffer del flujo.

    Ver también

    add a note add a note

    User Contributed Notes 3 notes

    up
    17
    cweiske at php dot net
    14 years ago
    Note that stream_socket_recvfrom() bypasses stream wrappers including TLS/SSL. While reading from an encrypted stream with fread() will return decrypted data, using stream_socket_recvfrom() will give you the original encrypted bytes.
    up
    4
    MagicalTux at php dot net
    13 years ago
    This method may return a peer address not compatible with stream_socket_sendto() if in ipv6.

    The ip returned by recvfrom is not within brackets ([]), and has the port appended, which makes it look like ::1:1234. To cut it properly, use strrpos()
    up
    1
    raat1979 at gmail dot com
    9 years ago
    Basically there is currently no real way to determine what the position of the Out of band data is in the tcp/ip stream.

    However, it seems that In my current environment (winsock: Windows / PHP 5.3.0) you do not peek beyond the OOB byte unless the buffer is empty
    reads do read beyond the OOB data. (I'll check my linux box later)

    You should be able to figure out the position of the OOB data by peeking and reading from the regular stream
    although it would not be 100% reliable as we do read beyond the OOB data when nothing is in front of it.
    depending on the high level protocol it might be possible
    to handle the specific "no data in front of out-of-band data" case

    <?php
    echo "<pre>";
    $sockets = stream_socket_pair(STREAM_PF_INET, STREAM_SOCK_STREAM, STREAM_IPPROTO_IP);
    $reader=$sockets[0];
    $writer=$sockets[1];

    stream_socket_sendto($writer,"abc");
    stream_socket_sendto($writer,"xyZ",STREAM_OOB); // ONLY THE LAST BYTE IS MARKED AS OOB DATA
    stream_socket_sendto($writer,"def");

    echo     "\r\n";
    echo     "Test 1, Peeking beyond oob when the read buffer becomes empty\r\n";
    echo     "The data order is 'abcxyZdef'\r\n";
    stream_select($r=array($reader), $w=array(), $x=array($reader),5);
    echo     "has regular:";var_dump(count($r)!==0);
    echo     "has oobData:";var_dump(count($x)!==0);
    echo     "<span style='color:blue' >Peek (9) regular:".stream_socket_recvfrom($reader,9,STREAM_PEEK)."</span>\r\n";
    echo     "<span style='color:green'>Peek (1) OobData:".stream_socket_recvfrom($reader,9,STREAM_OOB|STREAM_PEEK)."</span>\r\n";
    echo     "<span style='color:black'>READ (4) regular:".stream_socket_recvfrom($reader,4)."</span>\r\n";
    echo     "<span style='color:blue' >Peek (9) regular:".stream_socket_recvfrom($reader,9,STREAM_PEEK)."</span>\r\n";
    echo     "<span style='color:black'>READ (1) regular:".stream_socket_recvfrom($reader,1)."</span>\r\n";
    echo     "<span style='color:blue' >Peek (9) regular:".stream_socket_recvfrom($reader,9,STREAM_PEEK)."</span>\r\n";
    // read the OOB data
    echo "<span style='color:red'  >READ (9) OobData:".stream_socket_recvfrom($reader,9,STREAM_OOB)."</span>\r\n";

    echo     "<span style='color:blue' >Peek (9) regular:".stream_socket_recvfrom($reader,9,STREAM_PEEK)."</span>\r\n";

    fclose($sockets[0]);
    fclose($sockets[1]);
    echo     "</pre>";
    ?>
    outputs:
    Test 1, Peeking beyond oob when the read buffer becomes empty
    The data order is 'abcxyZdef'
    has regular:bool(true)
    has oobData:bool(true)
    Peek (9) regular:abcxy
    Peek (1) OobData:Z
    READ (4) regular:abcx
    Peek (9) regular:y
    READ (1) regular:y
    Peek (9) regular:def
    READ (9) OobData:Z
    Peek (9) regular:def

    <?php
    echo "<pre>";
    $sockets = stream_socket_pair(STREAM_PF_INET, STREAM_SOCK_STREAM, STREAM_IPPROTO_IP);
    $reader=$sockets[0];
    $writer=$sockets[1];

    stream_socket_sendto($writer,"Z",STREAM_OOB); // ONLY THE LAST BYTE IS MARKED AS OOB DATA
    stream_socket_sendto($writer,"abcxydef");

    echo     "<hr/>";
    echo     "\r\n";
    echo     "Test 2, peek if there is nothing in front of the OOB data\r\n";
    echo     "The data order is 'Zabcxydef'\r\n";
    stream_select($r=array($reader), $w=array(), $x=array($reader),5);
    echo     "has regular:";var_dump(count($r)!==0);
    echo     "has oobData:";var_dump(count($x)!==0);
    echo     "<span style='color:blue'>peek (9) regular:".stream_socket_recvfrom($reader,9,STREAM_PEEK)."</span>\r\n";
    echo     "<span style='color:red' >Peek (9) OobData:".stream_socket_recvfrom($reader,9,STREAM_OOB)."</span>\r\n";
    echo     "<span style='color:blue'>peek (9) regular:".stream_socket_recvfrom($reader,9,STREAM_PEEK)."</span>\r\n";
    echo     "</pre>";
    ?>
    Outputs:
    Test 2, peek if there is nothing in front of the OOB data
    The data order is 'Zabcxydef'
    has regular:bool(true)
    has oobData:bool(true)
    peek (9) regular:abcxydef
    Peek (9) OobData:Z
    peek (9) regular:abcxydef
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