socket_recvfrom
(PHP 4 >= 4.1.0, PHP 5)
socket_recvfrom — Receives data from a socket whether or not it is connection-oriented
Description
$socket
, string &$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
socketmust 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
lenbytes will be fetched from remote host. -
flags -
The value of
flagscan be any combination of the following flags, joined with the binary OR (|) operator.Possible values for flagsFlag Description MSG_OOBProcess out-of-band data. MSG_PEEKReceive data from the beginning of the receive queue without removing it from the queue. MSG_WAITALLBlock until at least lenare received. However, if a signal is caught or the remote host disconnects, the function may return less data.MSG_DONTWAITWith this flag set, the function returns even if it would normally have blocked. -
name -
If the socket is of the type
AF_UNIXtype,nameis the path to the file. Else, for unconnected sockets,nameis the IP address of, the remote host, orNULLif the socket is connection-oriented. -
port -
This argument only applies to
AF_INETandAF_INET6sockets, and specifies the remote port from which the data is received. If the socket is connection-oriented,portwill beNULL.
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 $port" . PHP_EOL;
?>
This example will initiate a UDP socket on port 1223 of 127.0.0.1 and print at most 12 characters received from a remote host.
Changelog
| Version | Description |
|---|---|
| 4.3.0 | socket_recvfrom() is now binary safe. |
See Also
- socket_recv() - Receives data from a connected socket
- socket_send() - Sends data to a connected socket
- socket_sendto() - Sends a message to a socket, whether it is connected or not
- socket_create() - Create a socket (endpoint for communication)
- socket_accept
- socket_bind
- socket_clear_error
- socket_close
- socket_cmsg_space
- socket_connect
- socket_create_listen
- socket_create_pair
- socket_create
- socket_get_option
- socket_getopt
- socket_getpeername
- socket_getsockname
- socket_import_stream
- socket_last_error
- socket_listen
- socket_read
- socket_recv
- socket_recvfrom
- socket_recvmsg
- socket_select
- socket_send
- socket_sendmsg
- socket_sendto
- socket_set_block
- socket_set_nonblock
- socket_set_option
- socket_setopt
- socket_shutdown
- socket_strerror
- socket_write
Коментарии
I'm confused about the rerturn value of socket_recvfrom(), it said -1 when failed, but when I call like this:
if (($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.
Pay attention! On some PHP version the MSG_DONTWAIT flag is not defined (see https://bugs.php.net/bug.php?id=48326)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.