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    socket_recvfrom

    (PHP 4 >= 4.1.0, PHP 5, PHP 7, PHP 8)

    socket_recvfrom — Receives data from a socket whether or not it is connection-oriented

    Description

    socket_recvfrom(
        Socket $socket,
        string &$data,
        int $length,
        int $flags,
        string &$address,
        int &$port = null
    ): int|false

    The socket_recvfrom() function receives length bytes of data in data from address on port port (if the socket is not of type AF_UNIX) using socket. socket_recvfrom() can be used to gather data from both connected and unconnected sockets. Additionally, one or more flags can be specified to modify the behaviour of the function.

    The address and port must be passed by reference. If the socket is not connection-oriented, address will be set to the internet protocol address of the remote host or the path to the UNIX socket. If the socket is connection-oriented, address is null. Additionally, the port will contain the port of the remote host in the case of an unconnected AF_INET or AF_INET6 socket.

    Note: This function is binary-safe.

    Parameters

    socket

    The socket must be a Socket instance previously created by socket_create().

    data

    The data received will be fetched to the variable specified with data.

    length

    Up to length 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 length 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.
    address

    If the socket is of the type AF_UNIX type, address is the path to the file. Else, for unconnected sockets, address is the IP address of, the remote host, or null if the socket is connection-oriented.

    port

    This argument only applies to AF_INET and AF_INET6 sockets, and specifies the remote port from which the data is received. If the socket is connection-oriented, port will be null.

    Return Values

    socket_recvfrom() 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.

    Changelog

    Version Description
    8.0.0 socket is a Socket instance now; previously, it was a resource.

    Examples

    Example #1 socket_recvfrom() example

    <?php

    $socket     = socket_create(AF_INET, SOCK_DGRAM, SOL_UDP);
    socket_bind($socket, '127.0.0.1', 1223);

    $from = '';
    $port = 0;
    socket_recvfrom($socket, $buf, 12, 0, $from, $port);

    echo     "Received $buf from remote address $from and remote port $port" . PHP_EOL;
    ?>

    This example will initiate a UDP socket on port 1223 of 127.0.0.1 and print at most 12 characters received from a remote host.

    See Also

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    User Contributed Notes 5 notes

    up
    3
    lorin dot weilenmann at gmail dot com
    9 years ago
    If you use socket_recvfrom on a UDP socket and combine it with the MSG_DONTWAIT flag, it will raise a PHP Warning if there is nothing to read. AFAIK, there is no way around that warning except suppressing it with @ (i.e. you cannot check if there is data before calling socket_recvfrom).
    up
    0
    ply2attoetensen-project.com
    7 years ago
    MSG_DONTWAIT doesn't seem to exist in windows sockets. However socket_set_nonblock() seems to do the trick.
    up
    0
    davide dot renzi at gmail dot com
    12 years ago
    Pay attention! On some PHP version the MSG_DONTWAIT flag is not defined (see https://bugs.php.net/bug.php?id=48326)
    up
    -4
    jaggerwang at gmail dot com
    17 years ago
    I'm confused about the rerturn value of socket_recvfrom(), it said -1 when failed, but when I call like this:

    if (($len = @socket_recvfrom($sock, $result, 32, 0, $ip, $port)) == -1) {
        if ($this->_debug) {
            echo "socket_read() failed: " . socket_strerror(socket_last_error()) . "\n";
        }
        return false;
    }

    variable $len = false, when I change the buffer length from 32 to 4096, it becomes right.
    up
    -10
    ryan_at_ryanfisher_dot_com
    18 years ago
    DNS RELAY USING UDP SOCKETS

    <?php

    while(TRUE) {
           $socket = socket_create(AF_INET, SOCK_DGRAM, SOL_UDP);
       if(    $socket === FALSE)
       {
           echo     'Socket_create failed: '.socket_strerror(socket_last_error())."\n";
       }
       if(!    socket_bind($socketD, "0.0.0.0", 53)) {
               socket_close($socketD);
           echo     'socket_bind failed: '.socket_strerror(socket_last_error())."\n";
       }
           socket_recvfrom($socket,$buf,65535,0,$clientIP,$clientPort);
           $stz = bin2hex($buf);
           $tx = "";
       for(    $i=0;$i<(strlen($stz)-26-10)/2;$i++)
       {
             $e = "00";
             $e[0] = $stz[$i*2+26];
             $e[1] = $stz[$i*2+27];
             $f = hexdec($e);
         if(    $f > 0 && $f < 32) $tx .= "."; else
             $tx .= sprintf("%c",$f);
       }
       echo     "$clientIP <".$tx.">\n";                                           
           $fp = fsockopen("udp://72.174.110.4",53,$errno,$errstr);
       if (!    $fp)
       {
           echo     "ERROR: $errno - $errstr<br />\n";
       }
       else
       {
              fwrite($fp,$buf);
              $ret = $buf;
              $ret = fread($fp,667);
              fclose($fp);
       }
      }
    socket_send($socket,$ret,667,0);
    }
    ?>
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