gen_udp(3)

MODULE
gen_udp - 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}. 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.

    The available options are:

        list:
            Received Packet is delivered as a list.

        binary:
            Received Packet is delivered as a binary.

        {ip, IPAddress}:
            If the host has several network interfaces, this option specifies which one to use.

        {fd, Fd}:
            If a UDP socket has somehow been opened without using gen_udp, use this option to pass in the file descriptor for it and create a Socket for it.

        inet6:
            Set up the socket for IPv6

        inet:
            Set up the socket for IPv4

        common inet options:
            The common inet options available are described in the setopts/2 function in the inet manual page. Default value for the receive buffer option is {recbuf, 8192}.

    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.

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