share metadata functions

lib/lnurl.js

@@ -1,4 +1,4 @@
-import { randomBytes } from 'crypto'
+import { randomBytes, createHash } from 'crypto'
 import { bech32 } from 'bech32'
 
 export function lnurlAuth (params) {
@@ -15,3 +15,14 @@ export function lnurlAuth (params) {
   const encodedUrl = bech32.encode('lnurl', words, 1023)
   return { secret, encodedUrl }
 }
+
+export function lnurlPayMetadataString (username) {
+  return JSON.stringify([[
+    'text/plain',
+    `Funding @${username} on stacker.news`
+  ]])
+}
+
+export function lnurlPayDescriptionHash (username) {
+  return createHash('sha256').update(lnurlPayMetadataString(username)).digest('hex')
+}

pages/api/lnurlp/[username]/index.js

@@ -1,4 +1,5 @@
 import models from '../../../../api/models'
+import { lnurlPayMetadataString } from '../../../../lib/lnurl'
 
 export default async ({ query: { username } }, res) => {
   const user = await models.user.findUnique({ where: { name: username } })
@@ -10,10 +11,7 @@ export default async ({ query: { username } }, res) => {
     callback: `https://stacker.news/api/lnurlp/${username}/pay`, // The URL from LN SERVICE which will accept the pay request parameters
     minSendable: 1000, // Min amount LN SERVICE is willing to receive, can not be less than 1 or more than `maxSendable`
     maxSendable: Number.MAX_SAFE_INTEGER,
-    metadata: [[
+    metadata: lnurlPayMetadataString(username), // Metadata json which must be presented as raw string here, this is required to pass signature verification at a later step
-      'text/plain', // must always be present
-      `Funding @${username} on stacker.news` // actual metadata content
-    ]], // Metadata json which must be presented as raw string here, this is required to pass signature verification at a later step
     tag: 'payRequest' // Type of LNURL
   })
 }

pages/api/lnurlp/[username]/pay.js

@@ -1,18 +1,7 @@
 import models from '../../../../api/models'
 import lnd from '../../../../api/lnd'
 import { createInvoice } from 'ln-service'
-import crypto from 'crypto'
+import { lnurlPayDescriptionHash } from '../../../../lib/lnurl'
-
-function utf8ByteArray (str) {
-  const utf8 = unescape(encodeURIComponent(str))
-
-  const arr = []
-  for (let i = 0; i < utf8.length; i++) {
-    arr.push(utf8.charCodeAt(i))
-  }
-
-  return Buffer.from(arr)
-}
 
 export default async ({ query: { username, amount } }, res) => {
   const user = await models.user.findUnique({ where: { name: username } })
@@ -27,10 +16,7 @@ export default async ({ query: { username, amount } }, res) => {
   // generate invoice
   const expiresAt = new Date(new Date().setHours(new Date().getHours() + 3))
   const description = `${amount} msats for @${user.name} on stacker.news`
-  const descriptionHash = crypto
+  const descriptionHash = lnurlPayDescriptionHash(username)
-    .createHash('sha256')
-    .update(utf8ByteArray(`Funding @${username} on stacker.news`))
-    .digest('hex')
   try {
     const invoice = await createInvoice({
       description,