Allow creation of reusable lnurl-pay endpoints

.mocharc.yaml

@@ -1,4 +1,4 @@
 require:
   - '@babel/polyfill'
   - '@babel/register'
-timeout: 5000
+timeout: 250000

bin/charged

@@ -16,6 +16,7 @@ const args = require('meow')(`
       -e, --node-env <env>      nodejs environment mode [default: production]
       --allow-cors <origin>     allow browser CORS requests from <origin> [default: off]
 
+      --url <url>               sets the base URL from which public pages will be served [default: use a relative URL]
       --rate-proxy <uri>        proxy to use for fetching exchange rate from bitstamp/coingecko [default: see proxy-from-env]
       --hook-proxy <uri>        proxy to use for web hook push requests [default: see proxy-from-env]
       --all-proxy <uri>         proxy to use for all http requests [default: see proxy-from-env]

migrations/20201101170804_lnurlpay.js

@@ -0,0 +1,26 @@
+exports.up = async db => {
+  await db.schema.createTable('lnurlpay_endpoint', t => {
+    t.string ('id').primary()
+    t.string ('metadata').notNullable().defaultTo('{}')
+    t.string ('min').notNullable()
+    t.string ('max').notNullable()
+    t.string ('currency').nullable()
+    t.string ('text').notNullable()
+    t.string ('image').nullable()
+    t.string ('other_metadata').nullable()
+    t.string ('success_text').nullable()
+    t.string ('success_url').nullable()
+    t.integer('comment_length').notNullable().defaultTo(0)
+    t.string ('webhook').nullable()
+  })
+  await db.schema.table('invoice', t => {
+    t.string('lnurlpay_endpoint').nullable()
+  })
+}
+
+exports.down = async db => {
+  await db.schema.dropTable('lnurlpay_endpoint')
+  await db.schema.table('invoice', t => {
+    t.dropColumn('lnurlpay_endpoint')
+  })
+}

package.json

@@ -18,6 +18,7 @@
   "dependencies": {
     "@babel/polyfill": "^7.10.1",
     "basic-auth": "^2.0.1",
+    "bech32": "^1.1.4",
     "big.js": "^5.2.2",
     "body-parser": "^1.19.0",
     "clightning-client": "^0.1.2",

src/app.js

@@ -37,6 +37,7 @@ const lnPath   = process.env.LN_PATH || join(require('os').homedir(), '.lightnin
 
   require('./invoicing')(app, payListen, model, auth, lnconf)
   require('./checkout')(app, payListen)
+  require('./lnurl')(app, payListen, model, auth, ln)
 
   require('./sse')(app, payListen, auth)
   require('./webhook')(app, payListen, model, auth)

src/lnurl.js

@@ -0,0 +1,164 @@
+import bech32 from 'bech32'
+import wrap from './lib/promise-wrap'
+import { toMsat } from './lib/exchange-rate'
+
+const debug = require('debug')('lightning-charge')
+
+module.exports = async (app, payListen, model, auth, ln) => {
+  // check if method invoicewithdescriptionhash exists
+  let help = await ln.help()
+  let foundCommand
+  for (let i = 0; i < help.help.length; i++) {
+    let command = help.help[i].command
+    if (command.slice(0, 26) !== 'invoicewithdescriptionhash') continue
+    foundCommand = true
+    break
+  }
+  if (!foundCommand) return
+
+  // define routes
+  const {
+    newInvoice, listInvoicesByLnurlPayEndpoint
+  , getLnurlPayEndpoint, listLnurlPayEndpoints
+  , setLnurlPayEndpoint, delLnurlPayEndpoint
+  } = model
+
+  app.get('/lnurlpays', auth, wrap(async (req, res) =>
+    res.status(200).send(
+      (await listLnurlPayEndpoints())
+        .map(lnurlpay => addBech32Lnurl(req, lnurlpay))
+    )))
+
+  app.post('/lnurlpay', auth, wrap(async (req, res) =>
+    res.status(201).send(
+      addBech32Lnurl(req, await setLnurlPayEndpoint(null, req.body))
+    )))
+
+  app.put('/lnurlpay/:id', auth, wrap(async (req, res) => {
+    const endpoint = await getLnurlPayEndpoint(req.params.id)
+    const updated = {...endpoint, ...req.body}
+    res.status(200).send(
+      addBech32Lnurl(req, await setLnurlPayEndpoint(req.params.id, updated))
+    )
+  }))
+
+  app.delete('/lnurlpay/:id', auth, wrap(async (req, res) => {
+    const deletedRows = await delLnurlPayEndpoint(req.params.id)
+    if (deletedRows) res.status(204)
+    else res.status(404)
+  }))
+
+  app.get('/lnurlpay/:id', auth, wrap(async (req, res) => {
+    const endpoint = await getLnurlPayEndpoint(req.params.id)
+    if (endpoint) res.status(200).send(addBech32Lnurl(req, endpoint))
+    else res.status(404)
+  }))
+
+  app.get('/lnurlpay/:id/invoices', auth, wrap(async (req, res) =>
+    res.send(await listInvoicesByLnurlPayEndpoint(req.params.id))))
+
+  // this is the actual endpoint users will hit
+  app.get('/lnurl/:id', wrap(async (req, res) => {
+    const endpoint = await getLnurlPayEndpoint(req.params.id)
+
+    if (!endpoint) {
+      res.status(404)
+      return
+    }
+
+    const current = endpoint.currency
+    const min = currency ? await toMsat(currency, endpoint.min) : endpoint.min
+    const max = currency ? await toMsat(currency, endpoint.max) : endpoint.max
+
+    let qs = new URLSearchParams(req.query).toString()
+    if (qs.length) qs = '?' + qs
+
+    res.status(200).send({
+      tag: 'payRequest'
+    , minSendable: min
+    , maxSendable: max
+    , metadata: makeMetadata(endpoint)
+    , commentAllowed: endpoint.comment_length
+    , callback: `https://${req.hostname}/lnurl/${lnurlpay.id}/callback${qs}`
+    })
+  }))
+
+  app.get('/lnurl/:id/callback', wrap(async (req, res) => {
+    const endpoint = await getLnurlPayEndpoint(req.params.id)
+    const amount = +req.query.amount
+
+    if (!amount)
+      return res.send({status: 'ERROR', reason: `invalid amount '${req.query.amount}'`})
+
+    const current = endpoint.currency
+    let min = currency ? await toMsat(currency, endpoint.min) : endpoint.min
+    let max = currency ? await toMsat(currency, endpoint.max) : endpoint.max
+    // account for currency variation
+    min = min * 0.99
+    max = max * 1.01
+
+    if (amount > max)
+      return res.send({status: 'ERROR', reason: `amount must be smaller than ${Math.floor(max / 1000)} sat`})
+    if (amount < min)
+      return res.send({status: 'ERROR', reason: `amount must be greater than ${Math.ceil(min / 1000)} sat`})
+
+    let invoiceMetadata = {...req.query}
+    delete invoiceMetadata.amount
+    delete invoiceMetadata.fromnodes
+    delete invoiceMetadata.nonce
+    invoiceMetadata = {...endpoint.metadata, ...invoiceMetadata}
+
+    // enforce comment length
+    invoiceMetadata.comment =
+      (comment.comment && req.query.comment)
+      ? (''+req.query.comment).substr(0, endpoint.comment)
+      : undefined
+
+    const invoice = await newInvoice({
+      description_hash: require('crypto')
+        .createHash('sha256')
+        .update(makeMetadata(lnurlpay))
+        .digest('hex')
+    , msatoshi: req.query.amount
+    , metadata: invoiceMetadata
+    , webhook: endpoint.webhook
+    , lnurlpay_endpoint: endpoint.id
+    , currency: endpoint.currency
+    })
+
+    let successAction
+    if (endpoint.success_url) {
+      successAction = {
+        tag: 'url'
+      , url: endpoint.success_url
+      , description: endpoint.success_text || ''
+      }
+    } else if (lnurlpay.success_text) {
+      successAction = {tag: 'message', message: endpoint.success_text}
+    }
+
+    res.status(200).send({
+      pr: invoice.payreq
+    , successAction
+    , routes: []
+    , disposable: false
+    })
+  }))
+}
+
+function makeMetadata (endpoint) {
+  return JSON.stringify(
+    [['text/plain', endpoint.text]]
+      .concat(endpoint.image ? ['image/png;base64', endpoint.image] : [])
+      .concat(JSON.parse(endpoint.other_metadata || []))
+  )
+}
+
+function addBech32Lnurl (req, lnurlpay) {
+  let base = process.env.URL || `https://${req.hostname}`
+  base = base[base.length - 1] === '/' ? base.slice(0, -1) : base
+  const url = `${base}/lnurl/${lnurlpay.id}`
+  const words = bech32.toWords(Buffer.from(url))
+  lnurlpay.bech32 = bech32.encode('lnurl', words, 2500).toUpperCase()
+  return lnurlpay
+}

src/model.js

@@ -4,6 +4,7 @@ import { toMsat } from './lib/exchange-rate'
 const debug  = require('debug')('lightning-charge')
     , status = inv => inv.pay_index ? 'paid' : inv.expires_at > now() ? 'unpaid' : 'expired'
     , format = inv => ({ ...inv, status: status(inv), msatoshi: (inv.msatoshi || null), metadata: JSON.parse(inv.metadata) })
+    , formatLnurlpay = lnurlpay => ({...lnurlpay, metadata: JSON.parse(lnurlpay.metadata)})
     , now    = _ => Date.now() / 1000 | 0
 
 // @XXX invoices that accept any amount are stored as msatoshi='' (empty string)
@@ -16,19 +17,21 @@ const defaultDesc = process.env.INVOICE_DESC_DEFAULT || 'Lightning Charge Invoic
 
 module.exports = (db, ln) => {
   const newInvoice = async props => {
-    const { currency, amount, expiry, description, metadata, webhook } = props
+    const { currency, amount, expiry, metadata, webhook, lnurlpay_endpoint } = props
 
     const id       = nanoid()
         , msatoshi = props.msatoshi ? ''+props.msatoshi : currency ? await toMsat(currency, amount) : ''
-        , desc     = props.description ? ''+props.description : defaultDesc
-        , lninv    = await ln.invoice(msatoshi || 'any', id, desc, expiry)
+        , desc     = props.description_hash || (props.description ? ''+props.description : defaultDesc)
+        , method   = props.description_hash ? 'invoicewithdescriptionhash' : 'invoice'
+        , lninv    = await ln.call(method, [msatoshi || 'any', id, desc, expiry])
 
     const invoice = {
       id, msatoshi, description: desc
     , quoted_currency: currency, quoted_amount: amount
     , rhash: lninv.payment_hash, payreq: lninv.bolt11
     , expires_at: lninv.expires_at, created_at: now()
     , metadata: JSON.stringify(metadata || null)
+    , lnurlpay_endpoint
     }
 
     debug('saving invoice:', invoice)
@@ -50,6 +53,65 @@ module.exports = (db, ln) => {
     await db('invoice').where({ id }).del()
   }
 
+  const listLnurlPayEndpoints = _ =>
+    db('lnurlpay_endpoint')
+      .then(rows => rows.map(formatLnurlpay))
+
+  const listInvoicesByLnurlPayEndpoint = lnurlpayId =>
+    db('invoice')
+      .where({ lnurlpay_endpoint: lnurlpayId })
+      .then(rows => rows.map(format))
+
+  const getLnurlPayEndpoint = async id => {
+    let endpoint = await db('lnurlpay_endpoint').where({ id }).first()
+    return endpoint && formatLnurlpay(endpoint)
+  }
+
+  const setLnurlPayEndpoint = async (id, props) => {
+    let lnurlpay
+    if (id) {
+      lnurlpay = await db('lnurlpay_endpoint').where({ id }).first()
+      lnurlpay = { ...lnurlpay, ...props }
+    } else lnurlpay = { ...props, id: nanoid() }
+
+    if (typeof props.metadata != 'undefined') {
+      let metadata = JSON.stringify(props.metadata || {})
+      if (metadata[0] != '{')
+        metadata = '{}'
+
+      lnurlpay.metadata = metadata
+    }
+
+    if (props.amount) {
+      lnurlpay.min = ''+props.amount
+      lnurlpay.max = ''+props.amount
+    } else if (props.min <= props.max) {
+      lnurlpay.min = ''+props.min
+      lnurlpay.max = ''+props.max
+    } else if (props.min > props.max) {
+      // silently correct a user error
+      lnurlpay.min = ''+props.max
+      lnurlpay.max = ''+props.min
+    }
+
+    if (lnurlpay.min && !lnurlpay.max)
+      lnurlpay.max = lnurlpay.min
+
+    if (lnurlpay.max && !lnurlpay.min)
+      lnurlpay.min = lnurlpay.max
+
+    await db('lnurlpay_endpoint')
+      .insert(lnurlpay)
+      .onConflict('id')
+      .merge()
+
+    return formatLnurlpay(lnurlpay)
+  }
+
+  const delLnurlPayEndpoint = async id => {
+    await db('lnurlpay_endpoint').where({ id }).del()
+  }
+
   const markPaid = (id, pay_index, paid_at, msatoshi_received) =>
     db('invoice').where({ id, pay_index: null })
                  .update({ pay_index, paid_at, msatoshi_received })
@@ -85,7 +147,8 @@ module.exports = (db, ln) => {
            : { requested_at: now(), success: false, resp_error: err })
 
   return { newInvoice, listInvoices, fetchInvoice, delInvoice
+         , listInvoicesByLnurlPayEndpoint, listLnurlPayEndpoints
+         , getLnurlPayEndpoint, setLnurlPayEndpoint, delLnurlPayEndpoint
          , getLastPaid, markPaid, delExpired
          , addHook, getHooks, logHook }
 }
-

test/invoicewithdescriptionhash-mock.sh

@@ -0,0 +1,22 @@
+#! /bin/sh
+
+# Eg. {"jsonrpc":"2.0","id":2,"method":"getmanifest","params":{}}\n\n
+read -r JSON
+read -r _
+id=$(echo "$JSON" | jq -r '.id')
+
+echo '{"jsonrpc":"2.0","id":'"$id"',"result":{"dynamic":true,"options":[],"rpcmethods":[{"name":"invoicewithdescriptionhash","usage":"<sat> <label><description_hash>","description":"this is just a worthless broken method for the tests!"}]}}'
+
+# Eg. {"jsonrpc":"2.0","id":5,"method":"init","params":{"options":{},"configuration":{"lightning-dir":"/home/rusty/.lightning","rpc-file":"lightning-rpc","startup":false}}}\n\n
+read -r JSON
+read -r _
+id=$(echo "$JSON" | jq -r '.id')
+rpc=$(echo "$JSON" | jq -r '.params.configuration | .["lightning-dir"] + "/" + .["rpc-file"]')
+
+echo '{"jsonrpc":"2.0","id":'"$id"',"result":{}}'
+
+# eg. { "jsonrpc" : "2.0", "method" : "invoicewithdescriptionhash 10sat label descriptionhash", "id" : 6, "params" :[ "hello"] }
+while read -r JSON; do
+    read -r _
+    echo "$JSON" | sed 's/invoicewithdescriptionhash/invoice/' | nc -U $rpc -W 1
+done