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The gen_udp module provides functions for communicating
with sockets using the UDP protocol.
ip_address()
see inet(3)
posix()
see inet(3)
socket()
as returned by open/1,2
open(Port) -> {ok, Socket} | {error, Reason}
open(Port, Options) -> {ok, Socket} | {error, Reason}
Types:
Port = 0..65535
Options = [Opt]
Opt -- see below
Socket = socket()
Reason = posix()
Associates a UDP port number (Port) with the calling
process.
The available options are:
list
Packet is delivered as a list.binary
Packet is delivered as a binary.{ip, ip_address()}
{fd, int()}
gen_udp, use this option to pass the file
descriptor for it.inet6
inet
Opt
The returned socket 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 Port == 0, the underlying OS assigns a free UDP
port, use inet:port/1 to retrieve it.
send(Socket, Address, Port, Packet) -> ok | {error, Reason}
Types:
Socket = socket()
Address = string() | atom() | ip_address()
Port = 0..65535
Packet = [char()] | binary()
Reason = not_owner | posix()
Sends a packet to the specified address and port.
The Address argument can be either a hostname, or an
IP address.
recv(Socket, Length) -> {ok, {Address, Port, Packet}}
| {error, Reason}
recv(Socket, Length, Timeout) ->
{ok, {Address, Port, Packet}} | {error, Reason}
Types:
Socket = socket()
Length = int()
Address = ip_address()
Port = 0..65535
Packet = [char()] | binary()
Timeout = int() | infinity
Reason = not_owner | posix()
This function receives a packet from a socket in passive mode.
The optional Timeout parameter specifies a timeout in
milliseconds. The default value is infinity.
controlling_process(Socket, Pid) -> ok
Types:
Socket = socket()
Pid = pid()
Assigns a new controlling process Pid to
Socket. The controlling process is the process which
receives messages from the socket.
close(Socket) -> ok | {error, Reason}
Types:
Socket = socket()
Reason = not_owner | posix()
Closes a UDP socket.