feat: add streaming payments tutorial (#2)

* feat: add streaming payments tutorial

* use psk

* use psk

* update streaming payments tutorial

* list trustlines tutorial

* fix: improve paragraph about BTP symmetry

client.js

@@ -0,0 +1,59 @@
+const IlpPacket = require('ilp-packet')
+const Plugin = require('ilp-plugin-xrp-escrow')
+const crypto = require('crypto')
+const fetch = require('node-fetch')
+const uuid = require('uuid/v4')
+function base64 (buf) { return buf.toString('base64').replace(/\+/g, '-').replace(/\//g, '_').replace(/=+$/, '') }
+function sha256 (secret) { return crypto.createHash('sha256').update(secret).digest() }
+function hmac (secret, input) { return crypto.createHmac('sha256', secret).update(input).digest() }
+
+const plugin = new Plugin({
+  secret: 'sndb5JDdyWiHZia9zv44zSr2itRy1',
+  account: 'rGtqDAJNTDMLaNNfq1RVYgPT8onFMj19Aj',
+  server: 'wss://s.altnet.rippletest.net:51233',
+  prefix: 'test.crypto.xrp.'
+})
+
+let counter = 0
+
+function sendTransfer (obj) {
+  obj.id = uuid()
+  obj.from = plugin.getAccount()
+  // to
+  obj.ledger = plugin.getInfo().prefix
+  // amount
+  // executionCondition
+  obj.expiresAt = new Date(new Date().getTime() + 1000000).toISOString()
+  return plugin.sendTransfer(obj).then(function () {
+    return obj.id
+  })
+}
+
+plugin.connect().then(function () {
+  return fetch('http://localhost:8000/')
+}).then(function (inRes) {
+  inRes.body.pipe(process.stdout)
+  const payHeaderParts = inRes.headers.get('Pay').split(' ')
+  console.log(payHeaderParts)
+  // e.g. Pay: 1 test.crypto.xrp.asdfaqefq3f.26wrgevaew SkTcFTZCBKgP6A6QOUVcwWCCgYIP4rJPHlIzreavHdU
+  setInterval(function () {
+    const ilpPacket = IlpPacket.serializeIlpPayment({
+      account: payHeaderParts[1] + '.' + (++counter),
+      amount: '1',
+      data: ''
+    })
+    const fulfillmentGenerator = hmac(Buffer.from(payHeaderParts[2], 'base64'), 'ilp_psk_condition')
+    const fulfillment =  hmac(fulfillmentGenerator, ilpPacket)
+    const condition = sha256(fulfillment)
+    sendTransfer({
+      to: payHeaderParts[1],
+      amount: '1',
+      executionCondition: base64(condition),
+      ilp: base64(ilpPacket)
+    }).then(function () {
+      // console.log('transfer sent')
+    }).catch(function (err) {
+      console.error(err.message)
+    })
+  }, 500)
+})

client2.js

@@ -0,0 +1,58 @@
+const IlpPacket = require('ilp-packet')
+const Plugin = require('ilp-plugin-payment-channel-framework')
+const crypto = require('crypto')
+const fetch = require('node-fetch')
+const uuid = require('uuid/v4')
+function base64 (buf) { return buf.toString('base64').replace(/\+/g, '-').replace(/\//g, '_').replace(/=+$/, '') }
+function sha256 (secret) { return crypto.createHash('sha256').update(secret).digest() }
+function hmac (secret, input) { return crypto.createHmac('sha256', secret).update(input).digest() }
+
+const plugin = new Plugin({
+  server: 'btp+ws://:@localhost:9000/'
+})
+
+let counter = 0
+
+function sendTransfer (obj) {
+  obj.id = uuid()
+  obj.from = plugin.getAccount()
+  // to
+  obj.ledger = plugin.getInfo().prefix
+  // amount
+  // executionCondition
+  obj.expiresAt = new Date(new Date().getTime() + 1000000).toISOString()
+  // console.log('calling sendTransfer!',  obj)
+  return plugin.sendTransfer(obj).then(function () {
+    return obj.id
+  })
+}
+
+plugin.connect().then(function () {
+  console.log('plugin connected')
+  return fetch('http://localhost:8000/')
+}).then(function (inRes) {
+  inRes.body.pipe(process.stdout)
+  const payHeaderParts = inRes.headers.get('Pay').split(' ')
+  console.log(payHeaderParts)
+  // e.g. Pay: 1 test.crypto.xrp.asdfaqefq3f.26wrgevaew SkTcFTZCBKgP6A6QOUVcwWCCgYIP4rJPHlIzreavHdU
+  setInterval(function () {
+    const ilpPacket = IlpPacket.serializeIlpPayment({
+      account: payHeaderParts[1] + '.' + (++counter),
+      amount: '1',
+      data: ''
+    })
+    const fulfillmentGenerator = hmac(Buffer.from(payHeaderParts[2], 'base64'), 'ilp_psk_condition')
+    const fulfillment =  hmac(fulfillmentGenerator, ilpPacket)
+    const condition = sha256(fulfillment)
+    sendTransfer({
+      to: payHeaderParts[1],
+      amount: '1',
+      executionCondition: base64(condition),
+      ilp: base64(ilpPacket)
+    }).then(function () {
+      // console.log('transfer sent')
+    }).catch(function (err) {
+      console.error(err.message)
+    })
+  }, 1)
+})

index.md

@@ -7,6 +7,8 @@ first time. The main programming language used is JavaScript.
 ## Tutorials
 
 * [The Letter Shop](./letter-shop)
+* [Streaming Payments](./streaming-payments)
+* [Trustlines](./trustlines)
 
 ## Versioning
 
@@ -20,6 +22,8 @@ Interledger Requests For Comments (IL-RFCs):
 * [IL-RFC-15, draft 1](https://interledger.org/rfcs/0015-ilp-addresses/draft-1.html): Interledger Addresses
 * [IL-RFC-22, draft 1](https://interledger.org/rfcs/0022-hashed-timelock-agreements/draft-1.html): Hashed Time Lock Agreements
 * [IL-RFC-19, draft 1](https://interledger.org/rfcs/0019-glossary/draft-1.html): Glossary
+* [IL-RFC-16, draft 3](https://interledger.org/rfcs/0016-pre-shared-key/draft-3.html): Pre-Shared Key (PSK)
+* [IL-RFC-23, draft 2](https://interledger.org/rfcs/0023-bilateral-transfer-protocol/draft-2.html): Bilateral Transfer Protocol (BTP)
 
 The software you will build during these tutorials will be compatible with software
 written by other developers, on several levels:

shop2.js

@@ -0,0 +1,56 @@
+const IlpPacket = require('ilp-packet')
+const http = require('http')
+const crypto = require('crypto')
+const Plugin = require('ilp-plugin-xrp-escrow')
+function base64 (buf) { return buf.toString('base64').replace(/\+/g, '-').replace(/\//g, '_').replace(/=+$/, '') }
+function sha256 (preimage) { return crypto.createHash('sha256').update(preimage).digest() }
+function hmac (secret, input) { return crypto.createHmac('sha256', secret).update(input).digest() }
+
+let users = {}
+
+const plugin = new Plugin({
+  secret: 'ssGjGT4sz4rp2xahcDj87P71rTYXo',
+  account: 'rrhnXcox5bEmZfJCHzPxajUtwdt772zrCW',
+  server: 'wss://s.altnet.rippletest.net:51233',
+  prefix: 'test.crypto.xrp.'
+})
+
+plugin.connect().then(function () {
+  plugin.on('incoming_prepare', function (transfer) {
+    const ilpPacket = Buffer.from(transfer.ilp, 'base64')
+    const ilpPacketContents = IlpPacket.deserializeIlpPayment(ilpPacket)
+    const parts = ilpPacketContents.account.split('.')
+    // 0: test, 1: crypto, 2: xrp, 3: rrhnXcox5bEmZfJCHzPxajUtwdt772zrCW, 4: userId, 5: paymentId
+    if (parts.length < 6 || typeof users[parts[4]] === 'undefined' || ilpPacketContents.amount !== transfer.amount) {
+      plugin.rejectIncomingTransfer(transfer.id, {}).catch(function () {})
+    } else {
+      const { secret, res } = users[parts[4]]
+      const fulfillmentGenerator = hmac(secret, 'ilp_psk_condition')
+      const fulfillment =  hmac(fulfillmentGenerator, ilpPacket)
+      const condition = sha256(fulfillment)
+      if (transfer.executionCondition === base64(condition)) {
+        plugin.fulfillCondition(transfer.id, base64(fulfillment)).then(function () {
+          const letter = ('ABCDEFGHIJKLMNOPQRSTUVWXYZ').split('')[(Math.floor(Math.random() * 26))]
+          res.write(letter)
+        }).catch(function (err) {
+          console.error(err.message)
+        })
+      } else {
+        console.log('no match!', { secret, fulfillment, condition, transfer })
+      }
+    }
+  })
+
+  http.createServer(function (req, res) {
+    const secret = crypto.randomBytes(32)
+    const user = base64(crypto.randomBytes(8))
+    users[user] = { secret, res }
+    console.log('user! writing head', user)
+    res.writeHead(200, {
+      'Pay': [ 1, plugin.getAccount() + '.' + user, base64(secret) ].join(' ')
+    })
+    // Flush the headers in a first TCP packet:
+    res.socket.write(res._header)
+    res._headerSent = true
+  }).listen(8000)
+})

shop3.js

@@ -0,0 +1,69 @@
+const IlpPacket = require('ilp-packet')
+const http = require('http')
+const crypto = require('crypto')
+const Plugin = require('ilp-plugin-payment-channel-framework')
+function base64 (buf) { return buf.toString('base64').replace(/\+/g, '-').replace(/\//g, '_').replace(/=+$/, '') }
+function sha256 (secret) { return crypto.createHash('sha256').update(secret).digest() }
+function hmac (secret, input) { return crypto.createHmac('sha256', secret).update(input).digest() }
+
+let users = {}
+const store = {}
+const plugin = new Plugin({
+  listener: {
+    port: 9000
+  },
+  incomingSecret: '',
+  maxBalance: '1000000000',
+  prefix: 'example.letter-shop.mytrustline.',
+  info: {
+    currencyScale: 9,
+    currencyCode: 'XRP',
+    prefix: 'example.letter-shop.mytrustline.',
+    connectors: []
+  },
+  _store: { // in-memory store for demo purposes
+    get: (k) => store[k],
+    put: (k, v) => { store[k] = v },
+    del: (k) => delete store[k]
+  }
+})
+
+plugin.connect().then(function () {
+  plugin.on('incoming_prepare', function (transfer) {
+    const ilpPacket = Buffer.from(transfer.ilp, 'base64')
+    const ilpPacketContents = IlpPacket.deserializeIlpPayment(ilpPacket)
+    const parts = ilpPacketContents.account.split('.')
+    // 0: test, 1: crypto, 2: xrp, 3: rrhnXcox5bEmZfJCHzPxajUtwdt772zrCW, 4: userId, 5: paymentId
+    if (parts.length < 6 || typeof users[parts[4]] === 'undefined' || ilpPacketContents.amount !== transfer.amount) {
+      plugin.rejectIncomingTransfer(transfer.id, {}).catch(function () {})
+    } else {
+      const { secret, res } = users[parts[4]]
+      const fulfillmentGenerator = hmac(secret, 'ilp_psk_condition')
+      const fulfillment =  hmac(fulfillmentGenerator, ilpPacket)
+      const condition = sha256(fulfillment)
+      if (transfer.executionCondition === base64(condition)) {
+        plugin.fulfillCondition(transfer.id, base64(fulfillment)).then(function () {
+          const letter = ('ABCDEFGHIJKLMNOPQRSTUVWXYZ').split('')[(Math.floor(Math.random() * 26))]
+          res.write(letter)
+        }).catch(function (err) {
+          console.error(err.message)
+        })
+      } else {
+        console.log('no match!', { secret, fulfillment, condition, transfer })
+      }
+    }
+  })
+
+  http.createServer(function (req, res) {
+    const secret = crypto.randomBytes(32)
+    const user = base64(crypto.randomBytes(8))
+    users[user] = { secret, res }
+    console.log('user! writing head', user)
+    res.writeHead(200, {
+      'Pay': [ 1, plugin.getAccount() + '.' + user, base64(secret) ].join(' ')
+    })
+    // Flush the headers in a first TCP packet:
+    res.socket.write(res._header)
+    res._headerSent = true
+  }).listen(8000)
+})