gen_udp

MODULE

gen_udp

MODULE SUMMARY

Interface to UDP.

DESCRIPTION

The gen_udp module is an interface to User Datagram Protocol (UDP).

The possible {error, Reason} results are described in the inet manual page.

EXPORTS

close(Socket) -> ok | {error, Reason}

Types:
Socket = Reason = term()

Removes the Socket created with open/1 or open/2.

controlling_process(Socket,NewOwner) ->

Types:
Socket = term()
NewOwner = pid()

The process associated with a Socket is changed to NewOwner. The NewOwner will receive all subsequent data.

open(Port) -> {ok, Socket } | { error, Reason }
open(Port,Options) -> {ok, Socket } | { error, Reason }

Types:
Port = integer(0..65535)
Options = list()
Socket = term()
Reason = term()

Associates a UDP port number (Port) with the calling process. It returns {ok, Socket}, or {error, Reason}. The returned Socket is used to send packets from this port with the send/4 function. Options is a list of options associated with this port.

When UDP packets arrive at the opened Port they will be delivered as messages of the type {udp, Socket, IP, InPortNo, Packet}

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.

The available options are:

list

Received Packet is delivered as a list.

binary

Received Packet is delivered as a binary.

common inet options

The common inet options available are described in the setopts/2 function in the inet manual page.

If you set Port to 0, the underlying Operating System assigns a free UDP port. (You can find out which port by calling inet:port(Socket).)

If any of the following functions are called with a Socket that was not opened by the calling process, they will return {error,not_owner}. The ownership of a Socket can be transferred to another process with controlling_process/2.

recv(Socket, Length) -> {ok,{Address, Port, Packet}} | {error, Reason}
recv(Socket, Length, Timeout)

Types:
Socket = socket()
Address = { integer(), integer(), integer(), integer()}
Port = integer(0..65535)
Length = integer()
Packet = list() | binary()
Timeout = integer()
Reason = atom()

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.

send(S,Address,Port,Packet) -> ok | {error, Reason}

Types:
Address = { integer(), integer(), integer(), integer()} | atom() | string()
Port = integer(0..65535)
Packet = [byte()] | binary()
Reason = term()

Sends Packet to the specified address (address, port). It returns ok, or {error, Reason}. Address can be an IP address expressed as a tuple, for example {192, 0, 0, 1}. It can also be a host name expressed as an atom or a string, for example 'somehost.some.domain'. Port is an integer, and Packet is either a list of bytes or a binary.

AUTHORS

tony@erix.ericsson.se - support@erlang.ericsson.se