enet

A complete re-implementation of the ENet protocol in Erlang/OTP.

API

The module enet presents the API of enet.

Data Types

port_number() = 0..65535

peer_count() = 1..255

channel_count() = 1..255

bytes_per_second() = non_neg_integer()

channels() = #{ non_neg_integer() := pid() }

Functions

start_host/3

start_host(Port, ConnectFun, Options) -> {ok, port_number()} | {error, term()}

    Port = port_number()
    ConnectFun = mfa() | fun((PeerInfo) -> ConnectFunResult)
    PeerInfo = map()
    ConnectFunResult = {ok, pid()} | {error, term()}
    Options = [Option]
    Option =
      {peer_limit, peer_count()} |
      {channel_limit, channel_count()} |
      {incoming_bandwidth, bytes_per_second()} |
      {outgoing_bandwidth, bytes_per_second()}

Start a new host. If Port set to 0, the port will be dynamically assigned by the underlying operating system. The assigned port is returned.

The ConnectFun function or MFA tuple will be called when a new peer has started and a connection to a remote peer has been established. This function is expected to spawn a new process and return a pid to which all messages from the new peer will be sent.

stop_host/1

stop_host(Port) -> ok

    Port = port_number()

Stop a host listening on Port.

connect_peer/4

connect_peer(HostPort, IP, RemotePort, ChannelCount) -> {ok, Peer} | {error, atom()}

    HostPort = port_number()
    IP = string()
    RemotePort = port_number()
    ChannelCount = channel_count()
    Peer = pid()

Start a new peer on the host listening on HostPort connecting to a remote host on address IP:RemotePort. The peer process will call ConnectFun (given to start_host/3) when the handshake has been completed successfully.

disconnect_peer/1

disconnect_peer(Peer) -> ok

    Peer = pid()

Disconnect Peer.

disconnect_peer_now/1

disconnect_peer_now(Peer) -> ok

    Peer = pid()

Disconnect Peer immediately without waiting for an ACK from the remote peer.

send_unsequenced/2

send_unsequenced(Channel, Data) -> ok

    Channel = pid()
    Data = iodata()

Send unsequenced data to the remote peer over Channel.

send_unreliable/2

send_unreliable(Channel, Data) -> ok

    Channel = pid()
    Data = iodata()

Send unreliable data to the remote peer over Channel.

send_reliable/2

send_reliable(Channel, Data) -> ok

    Channel = pid()
    Data = iodata()

Send reliable data to the remote peer over Channel.

broadcast_unsequenced/3

broadcast_unsequenced(HostPort, ChannelID, Data) -> ok

    HostPort = port_number()
    ChannelID = integer()
    Data = iodata()

Broadcast unsequenced data to all peers connected to HostPort on ChannelID.

broadcast_unreliable/3

broadcast_unreliable(HostPort, ChannelID, Data) -> ok

    HostPort = port_number()
    ChannelID = integer()
    Data = iodata()

Broadcast unreliable data to all peers connected to HostPort on ChannelID.

broadcast_reliable/3

broadcast_reliable(HostPort, ChannelID, Data) -> ok

    HostPort = port_number()
    ChannelID = integer()
    Data = iodata()

Broadcast reliable data to all peers connected to HostPort on ChannelID.

Examples

Creating an ENet server

ListeningPort = 1234,
ConnectFun = fun(PeerInfo) ->
                     server_supervisor:start_worker(PeerInfo)
             end,
Options = [{peer_limit, 8}, {channel_limit, 3}],
{ok, Host} = enet:start_host(ListeningPort, ConnectFun, Options),
...
...
...
enet:stop_host(Host).

Creating an ENet client and connecting to a server

ListeningPort = 0, %% Port will be dynamically assigned
ConnectFun = fun(PeerInfo) ->
                     client_supervisor:start_worker(PeerInfo)
             end,
Options = [{peer_limit, 1}, {channel_limit, 3}],
{ok, Host} = enet:start_host(ListeningPort, ConnectFun, Options),
...
...
RemoteHost = "...."
Port = 1234,
ChannelCount = 3
{ok, Peer} = enet:connect_peer(Host, RemoteHost, Port, ChannelCount),
...
...
enet:stop_host(Host).

Sending packets to an ENet peer

worker_loop(PeerInfo = #{channels := Channels}, State) ->
    ...
    ...
    {ok, Channel0} = maps:find(0, Channels),
    Data = <<"packet">>,
    enet:send_unsequenced(Channel0, Data),
    enet:send_unreliable(Channel0, Data),
    enet:send_reliable(Channel0, Data),
    ...
    ...
    worker_loop(PeerInfo, State).

Receiving packets from an ENet peer

worker_loop(PeerInfo, State) ->
    ...
    ...
    receive
        {enet, ChannelID, #unsequenced{ data = Packet }} ->
            %% Handle the Packet
            ok;
        {enet, ChannelID, #unreliable{ data = Packet }} ->
            %% Handle the Packet
            ok;
        {enet, ChannelID, #reliable{ data = Packet }} ->
            %% Handle the Packet
            ok
    end,
    ...
    ...
    worker_loop(PeerInfo, State).