PHP 7.0.6 Released

    socket_recvfrom

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

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

    Description

    int socket_recvfrom ( resource $socket , string &$buf , int $len , int $flags , string &$name [, int &$port ] )

    The socket_recvfrom() function receives len bytes of data in buf from name 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 name and port must be passed by reference. If the socket is not connection-oriented, name 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, name 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.

    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.

    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.
    name

    If the socket is of the type AF_UNIX type, name is the path to the file. Else, for unconnected sockets, name 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.

    Examples

    Example #1 socket_recvfrom() example

    <?php
    error_reporting    (E_ALL | E_STRICT);

    $socket = socket_create(AF_INET, SOCK_DGRAM, SOL_UDP);
    socket_bind($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.

    Changelog

    Version Description
    4.3.0 socket_recvfrom() is now binary safe.

    See Also

    User Contributed Notes

    davide dot renzi at gmail dot com
    4 years ago
    Pay attention! On some PHP version the MSG_DONTWAIT flag is not defined (see https://bugs.php.net/bug.php?id=48326)
    lorin dot weilenmann at gmail dot com
    8 months 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).
    jaggerwang at gmail dot com
    8 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.
    ryan_at_ryanfisher_dot_com
    9 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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