PHP - Manual: socket_recvfrom

2024-11-14

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

说明

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.

注意: 此函数可安全用于二进制对象。

参数

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.

返回值

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.

更新日志

版本	说明
8.0.0	现在 `socket` 是 Socket 实例，之前是 resource。

范例

示例 #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.

参见

socket_recv() - 从已连接的 socket 接收数据
socket_send() - Sends data to a connected socket
socket_sendto() - Sends a message to a socket, whether it is connected or not
socket_create() - 创建一个套接字（通讯节点）

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User Contributed Notes 5 notes

down

lorin dot weilenmann at gmail dot com ¶

6 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).

down

ply2attoetensen-project.com ¶

5 years ago


MSG_DONTWAIT doesn't seem to exist in windows sockets. However socket_set_nonblock() seems to do the trick.

down

davide dot renzi at gmail dot com ¶

10 years ago


Pay attention! On some PHP version the MSG_DONTWAIT flag is not defined (see https://bugs.php.net/bug.php?id=48326)

down

-2

jaggerwang at gmail dot com ¶

14 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.

down

-10

ryan_at_ryanfisher_dot_com ¶

15 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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官方地址：https://www.php.net/manual/en/function.socket-recvfrom.php

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PHP官方手册 - 互联网笔记

socket_recvfrom

说明

参数

返回值

更新日志

范例

参见

User Contributed Notes 5 notes