gen_udp
(kernel)Interface to UDP sockets
The gen_udp
module provides functions for communicating
with sockets using the UDP protocol.
As returned by open/1,2.
Functions
open(Port) -> {ok, Socket} | {error, Reason}
open(Port, Opts) -> {ok, Socket} | {error, Reason}
Associates a UDP port number (
) with the calling
process.
The available options are:
list
Received Packet
is delivered as a list.
binary
Received Packet
is delivered as a binary.
{ip, ip_address()}
If the host has several network interfaces, this option specifies which one to use.
{fd, integer() >= 0}
If a socket has somehow been opened without using
gen_udp
, use this option to pass the file
descriptor for it.
inet6
Set up the socket for IPv6.
inet
Set up the socket for IPv4.
Opt
See inet:setopts/2.
The returned socket
is used to send packets
from this port with send/4
. When UDP packets arrive at
the opened port, they are delivered as messages:
{udp, Socket, IP, InPortNo, Packet}
Note that arriving UDP packets that are longer than the receive buffer option specifies, might be truncated without warning.
IP
and InPortNo
define the address from which
Packet
came. Packet
is a list of bytes if
the option list
was specified. Packet
is a
binary if the option binary
was specified.
Default value for the receive buffer option is
{recbuf, 8192}
.
If
, the underlying OS assigns a free UDP
port, use inet:port/1
to retrieve it.
send(Socket, Address, Port, Packet) -> ok | {error, Reason}
Sends a packet to the specified address and port.
The
argument can be either a hostname, or an
IP address.
recv/2
recv/3
This function receives a packet from a socket in passive mode.
The optional
parameter specifies a timeout in
milliseconds. The default value is infinity
.
controlling_process(Socket, Pid) -> ok
Assigns a new controlling process
to
. The controlling process is the process which
receives messages from the socket.
close(Socket) -> ok
Closes a UDP socket.