enet-js

Modern Node.js bindings for ENet, the reliable UDP networking library.

This package uses N-API to provide a foreign function interface for the native C library

Note that some ENet functions have not been covered yet, so feel free to contribute the ones you need

Versioning

The <major>.<minor> version matches the supported ENet version

Install

---

NOTE: Node.js 14+ is currently unsupported due to a N-API bug

---

npm install --save-exact enet-js@latest

Then, add a field in your package.json indicating the path where the dynamic library is located. If you have binaries for multiple platforms, omit the extension

{
  "enetLibPath": "path/to/enet(.dll|.dylib|.so)"
}

To get the dynamic library, compile ENet following the instructions at http://enet.bespin.org/Installation.html.

Usage

Initialization

http://enet.bespin.org/Tutorial.html#Initialization

import { enet } from "enet-js";

const start = (): void => {
  if (enet.initialize() === 0) {
    process.on("SIGINT", (): void => {
      enet.deinitialize();
      process.exit();
    });

    // ...
  } else {
    console.error("Unable to initialize ENet");
    process.exit(1);
  }
};

start();

Creating an ENet server

http://enet.bespin.org/Tutorial.html#CreateServer

const address: IENetAddress = {
  // Bind the server to the default localhost.
  host: ENET_HOST_ANY,
  port: 1234
};
const host: IENetHost | null = enet.host.create(
  // the address to bind the server host to
  address,
  // allow up to 32 clients and/or outgoing connections
  32,
  // allow up to 2 channels to be used, 0 and 1
  2,
  // assume any amount of incoming bandwidth
  0,
  // assume any amount of outgoing bandwidth
  0
);

if (host === null) {
  console.error("Unable to create host");
  process.exit(1);
} else {
  console.log("Server running on port", address.port);

  // ...

  enet.host.destroy(host);
}

Creating an ENet client

http://enet.bespin.org/Tutorial.html#CreateClient

const host: IENetHost | null = enet.host.create(
  // create a client host
  null,
  // only allow 1 outgoing connection
  1,
  // allow up to 2 channels to be used, 0 and 1
  2,
  // assume any amount of incoming bandwidth
  0,
  // assume any amount of outgoing bandwidth
  0
);

if (host === null) {
  console.error("Unable to create host");
  process.exit(1);
} else {

  // ...

  enet.host.destroy(host);
}

Managing an ENet host

http://enet.bespin.org/Tutorial.html#ManageHost

setInterval((): void => {
  // Wait up to 1000 milliseconds for an event.
  const event: IENetEvent | null = enet.host.service(host, 1000);

  if (event) {
    switch (event.type) {
      case ENetEventType.none:
        break;

      case ENetEventType.connect:
        console.log(
          "Client connected",
          event.peer.address.host,
          event.peer.address.port
        );
        break;

      case ENetEventType.disconnect:
        console.log(
          "Client disconnected",
          event.peer.address.host,
          event.peer.address.port
        );
        break;

      case ENetEventType.receive:
        console.log(
          "Packet received from channel",
          event.channelID,
          event.packet.data
        );
        // Clean up the packet now that we're done using it.
        enet.packet.destroy(event.packet);
        break;
    }
  }
});

Sending a packet to an ENet peer

http://enet.bespin.org/Tutorial.html#SendingPacket

// Create a reliable packet of size 7 containing "packet\0"
const packet: IENetPacket | null = enet.packet.create(
  Buffer.from("packet\0"),
  ENetPacketFlag.reliable
);

/* Send the packet to the peer over channel id 0.
 * One could also broadcast the packet
 * using enet.host.broadcast(host, 0, packet);
 */
if (packet) {
  enet.peer.send(peer, 0, packet);
  // One could just use enet.host.service() instead.
  enet.host.flush(host);
}

Disconnecting an ENet peer

http://enet.bespin.org/Tutorial.html#Disconnecting

enet.peer.disconnect(peer, 0);
/* Allow up to 3 seconds for the disconnect to succeed
 * and drop any packets received packets.
 */
const event: IENetEvent | null = enet.host.service(host, 3000);

if (event) {
  switch (event.type) {
    case ENetEventType.disconnect:
      console.log("Disconnection succeeded.");
      return;

    case ENetEventType.receive:
      enet.packet.destroy(packet);
      break;
  }
}
/* We've arrived here, so the disconnect attempt didn't
 * succeed yet. Force the connection down.
 */
enet.peer.reset(peer);

Connecting to an ENet host

http://enet.bespin.org/Tutorial.html#Connecting

// Connect to 127.0.0.1:1234.
const address: IENetAddress = { host: "127.0.0.1", port: 1234 };

// Initiate the connection, allocating the two channels 0 and 1.
const peer: IENetPeer | null = enet.host.connect(host, address, 2, 0);

if (peer === null) {
   console.error("No available peers for initiating an ENet connection");
   process.exit(1);
}

// Wait up to 5 seconds for the connection attempt to succeed.
const event: IENetEvent | null = enet.host.service(host, 5000);

if (event && event.type === ENetEventType.connect) {
  console.log("Connection to 127.0.0.1:1234 succeeded.");

  // ...

} else {
  /* Either the 5 seconds are up or a disconnect event was
   * received. Reset the peer in the event the 5 seconds
   * had run out without any significant event.
   */
  enet.peer.reset(peer);
  console.error("Connection to 127.0.0.1:1234 failed.");
}

Docs

This package aims to serve only as a compatibility layer without expanding the functionality, which means the functions and data structures mirror the native ones, whose docs can be found at http://enet.bespin.org/.

This package also provides TypeScript type definitions to help ensure proper usage.