(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
$socket,&$data,$length,$flags,&$address,&$port = null
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.
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.
| 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.
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.
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 $port" . PHP_EOL;
?>This example will initiate a UDP socket on port 1223 of 127.0.0.1 and print at most 12 characters received from a remote host.
If you use socket_recvfrom on a UDP socket and combine it with the MSG_DONTWAIT flag, it will raise a PHP Warning if there is nothing to read. AFAIK, there is no way around that warning except suppressing it with @ (i.e. you cannot check if there is data before calling socket_recvfrom).MSG_DONTWAIT doesn't seem to exist in windows sockets. However socket_set_nonblock() seems to do the trick.Pay attention! On some PHP version the MSG_DONTWAIT flag is not defined (see https://bugs.php.net/bug.php?id=48326)I'm confused about the rerturn value of socket_recvfrom(), it said -1 when failed, but when I call like this:
if (($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.