lnurl snippets

flask-lnurl.py

import hashlib
import json
from flask import Flask, jsonify, request

app = Flask(__name__)
BASE_URL = 'https://myservice.com'

@app.route('/lnurl-one')
def lnurl_one():
    return jsonify({
      'tag': 'payRequest',
      'callback': BASE_URL + '/lnurl-two',
      'metadata': do_metadata(question),
      'minSendable': 1000,
      'maxSendable': 1000,
    })

@app.route('/lnurl-two')
def lnurl_two(i):
    description_hash = hashlib.sha256(do_metadata()).hexdigest()

    return jsonify({
        'pr': make_bolt11(description_hash),
        'routes': [],
        'successAction': None
    })

def do_metadata():
    return json.dumps([['text/plain', 'something']])
  
def make_bolt11(description_hash):
    pass

lnurl-withdraw-flow.txt

                               +----------------------------+                      +--------------------+
                               |server                      |                      |wallet              |
                               +----------------------------+                      +--------------------+

                                is listening at
                                https://x.com/.
                                                                                    user visits site,
                                                                                    has some balance to
                                                                                    withdraw.

                                generates a secret URL
                                specific to the user,
                                say, x.com/bob/withdraw?
                                     secret=123abc456xyz

                                encodes that as bech32
                                with human-readable-prefix
                                `lnurl`.

                                displays it as a QR code.

                                                                                    scans the QR code,
                                                                                    decodes the bech32,
                                                                                    calls the URL.

                                when receiving a
+--------------------+          call at /bob/withdraw
|if something is     |          checks the given secret
|wrong, the server   |          query string.
|can just return     |
|                    |          if everything is ok and
|{                   |          this is really bob, checks
|  "status": "ERROR",|          bob's balance.
|  "reason": "..."   |
|}                   |          bob's balance is 23 sat.
+--------------------+
                                returns an answer like

+--------------------+ {
|if the server wants |   "defaultDescription": "withdraw from x.com",
|the user to withdraw|   "minWithdrawable": 0,
|a fixed amount,     |   "maxWithdrawable": 23,
|make min and max    |   "tag": "withdrawRequest",
|equal.              |   "k1": "123abc456xyz",
+--------------------+   "callback": "https://x.com/bob/withdraw/fulfill"
                       }


                                                                                    using the received params,
                                                                                    the wallet shows a prefilled
                                                                                    invoice generation screen.

                                                                                    user selects the amount and
                                                                                    confirms.

                                                                                    the wallet generates the
                                                                                    invoice and calls

                                                                                    https://x.com/bob/withdraw/
                                                                                    fulfill?k1=123abc456xyz&
                                                                                    pr=lnbc...

                                                                                    the wallet is now ready to
                                                                                    receive the payment.

+--------------------+          upon receiving the bolt11
|if something is     |          invoice as the query string
|wrong, the server   |          on /bob/withdraw/fulfill,
|can just return     |          checks "k1" for the secret.
|                    |
|{                   |          if everything is ok, pays
|  "status": "ERROR",|          the invoice.
|  "reason": "..."   |
|}                   |          returns {"status": "OK"}
+--------------------+