PHP: Hypertext Preprocessor (original) (raw)
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
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](reserved.constants.php#constant.null). Additionally, the port will contain the port of the remote host in the case of an unconnected [AF_INET](sockets.constants.php#constant.af-inet) or**[AF_INET6](sockets.constants.php#constant.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 withdata.
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](sockets.constants.php#constant.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](reserved.constants.php#constant.null) if the socket is connection-oriented.
port
This argument only applies to [AF_INET](sockets.constants.php#constant.af-inet) and**[AF_INET6](sockets.constants.php#constant.af-inet6)** sockets, and specifies the remote port from which the data is received. If the socket is connection-oriented,port will be [null](reserved.constants.php#constant.null).
Return Values
socket_recvfrom() returns the number of bytes received, or [false](reserved.constants.php#constant.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,buf, 12, 0, buf,12,0,from, $port);
echo
"Received buffromremoteaddressbuf from remote address buffromremoteaddressfrom and remote port $port" . PHP_EOL;
?>`
This example will initiate a UDP socket on port 1223 of 127.0.0.1 and print at most 12 characters received from a remote host.
See Also
- socket_recv() - Receives data from a connected socket
- socket_send() - Sends data to a connected socket
- socket_sendto() - Sends a message to a socket, whether it is connected or not
- socket_create() - Create a socket (endpoint for communication)
Found A Problem?
lorin dot weilenmann at gmail dot com ¶
9 years ago
If you use socket_recvfrom on a UDP socket and combine it with the MSG_DONTWAIT flag, it will raise a PHP Warning if there is nothing to read. AFAIK, there is no way around that warning except suppressing it with @ (i.e. you cannot check if there is data before calling socket_recvfrom).
8 years ago
MSG_DONTWAIT doesn't seem to exist in windows sockets. However socket_set_nonblock() seems to do the trick.
17 years ago
`I'm confused about the rerturn value of socket_recvfrom(), it said -1 when failed, but when I call like this:
if (($len = @socket_recvfrom($sock, result,32,0,result, 32, 0, 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.
`