xmpp-lightning-antispam/index.js

import { client, xml } from "@xmpp/client";
// import debug from "@xmpp/debug";
import config from "./config.js";
import Lndhub from "./lib/lndhub.js";
import {
  randomHex,
  pingXml,
  isPingResponse,
  roomDirectMessageXml,
  grantVoiceMessageXml,
  parseForm,
  isVoiceRequest,
} from "./lib/utils.js";

const xmpp = client(config.xmpp);

// debug(xmpp, true);

const connectRetryInMilliseconds = 5000;
const pingIntervalInMilliseconds = 3000;
const pingTimeoutInMilliseconds = 10000;
let pingInterval = null;
let lastPingSuccess = null;

const lndhub = new Lndhub(config.lndhub.endpoint);

function checkAndSendPing () {
  const now = new Date();
  if ((now.getTime() - lastPingSuccess.getTime()) > pingTimeoutInMilliseconds) {
    console.log(`No ping response received in ${pingTimeoutInMilliseconds/1000} seconds, reconnecting`);
    clearInterval(pingInterval);
    xmpp.stop().catch(console.error);
  } else {
    xmpp.send(pingXml(config.xmpp.service))
        .catch(err => console.warn(err));
  }
}

function startPingInterval () {
  if (pingInterval) { clearInterval(pingInterval); }
  pingInterval = setInterval(checkAndSendPing, pingIntervalInMilliseconds);
}

function waitForInvoicePaid (room, nick, invoice, retries=0) {
  let timeout = 3000;

  if (retries >= 300) {
    console.log(`Invoice not paid after 15 minutes: ${invoice.payment_hash}`);
    let timeout = 5000;
    if (retries >= 500) {
      // TODO ask user to request voice again to create a new invoice
      return false;
    }
  }

  lndhub.getInvoice(invoice.payment_hash).then(async data => {
    if (data && data.is_paid) {
      console.log(`Invoice paid: ${invoice.payment_hash}`);
      await grantVoice(room, nick);
    } else {
      if (!data) console.warn('Fetching invoice status failed');
      setTimeout(waitForInvoicePaid, timeout, room, nick, invoice, retries++);
    }
  });
}

async function respondToVoiceRequest (room, nick, invoice) {
  const welcomeMessage = `
Welcome, ${nick}! I see you're interested in joining the conversation.

You can wait for a human moderator to approve your request, but it may take a while. You may also prove that you're not a spambot by donating a small amount of sats for the maintenance of this chat server via the following Lightning invoice. I will immediately approve your request in that case.

${invoice.payment_request}
`;

  await xmpp.send(roomDirectMessageXml(room, nick, welcomeMessage));
}

async function grantVoice (room, nick) {
  console.log(`Granting voice to ${nick} in ${room}`);
  await xmpp.send(grantVoiceMessageXml(room, nick));

  const message = `Thanks ${nick}, and welcome aboard! You can send messages to the channel now.`;
  await xmpp.send(roomDirectMessageXml(room, nick, message));
}

async function handleVoiceRequest (stanza) {
  try {
    const formFields = parseForm(stanza);
    const room = stanza.attrs.from;
    // const jid  = formFields.find(f => f.name === "muc#jid").value;
    const nick = formFields.find(f => f.name === "muc#roomnick").value;
    console.log(`${nick} requested voice in ${room}`);

    const invoice = await lndhub.createInvoice(config.amounts.voice, `Donation for ${room}`);
    if (invoice) {
      console.log(`Created lightning invoice for ${nick}: ${invoice.payment_hash}`)
      await respondToVoiceRequest(room, nick, invoice);
      waitForInvoicePaid(room, nick, invoice);
    } else {
      console.warn(`Invoice creation failed!`);
      // TODO notify ops contact
    }
  } catch(err) {
    console.error(err);
  }
}

async function connectXmpp () {
  await xmpp.start().catch(err => {
    console.log(`Connect error: ${err}`);
    console.log(`Retrying in ${connectRetryInMilliseconds/1000} seconds`);
    setTimeout(async () => {
      await connectXmpp();
    }, connectRetryInMilliseconds);
  });
}

function connectLndhub () {
  return lndhub.auth(config.lndhub.username, config.lndhub.password).then(connected => {
    if (connected) {
      console.log("Connected to Lndhub");
      // automatically refresh auth token once a day
      setInterval(() => lndhub.reauth(), 86400000);
    } else {
      process.exit(1);
    }
  }).catch(err => {
    console.error(`Lndhub connection failed: ${err}`);
  });
}

function handlePingResponse (stanza) {
  lastPingSuccess = new Date();
}

function readIq (stanza) {
  if (isPingResponse(stanza)) handlePingResponse(stanza);
}

function readMessage (stanza) {
  if (isVoiceRequest(stanza)) handleVoiceRequest(stanza);
}

xmpp.on("error", (err) => {
  console.error(err);
});

xmpp.on("offline", () => {
  console.log("Offline");
  connectXmpp();
});

xmpp.on("online", async (address) => {
  console.log("Connected to XMPP server");

  for (const jid of config.xmpp.rooms) {
    const msg = xml("presence", { to: `${jid}/${config.xmpp.nick}` });
    await xmpp.send(msg);
  }

  connectLndhub();

  lastPingSuccess = new Date();
  startPingInterval();
});

xmpp.on("stanza", async (stanza) => {
  if (stanza.is("iq")) readIq(stanza);
  if (stanza.is("message")) readMessage(stanza);
});

xmpp.on("status", (status) => {
  console.debug("XMPP status:", status);
});

connectXmpp();