Merge pull request #1 from ndeet/satodri-18-fixes

Hardening the payment flow

payment_btcpayserver/controllers/main.py

@@ -21,11 +21,10 @@
 
 import json
 import logging
-import pprint
 
 from werkzeug import urls
 
-from odoo import http
+from odoo import _, http
 from odoo.exceptions import ValidationError
 from odoo.http import request
 
@@ -47,6 +46,125 @@ class BTCPayController(http.Controller):
             tokens={provider.btcpay_facade: provider.btcpay_token},
         )
 
+    @staticmethod
+    def _lock_transaction(tx_sudo):
+        """Lock a transaction until the current database transaction ends.
+
+        Checkout and IPN requests can arrive concurrently. Serializing them on
+        the payment transaction prevents two checkout requests from creating
+        separate invoices and makes an IPN re-check the invoice ID after a
+        checkout replaces an expired invoice.
+        """
+        tx_sudo.ensure_one()
+        tx_sudo.flush_recordset()
+        tx_sudo.env.cr.execute(
+            "SELECT id FROM payment_transaction WHERE id = %s FOR UPDATE",
+            [tx_sudo.id],
+        )
+        tx_sudo.invalidate_recordset([
+            'state', 'btcpay_invoiceId', 'provider_reference',
+        ])
+
+    @staticmethod
+    def _ensure_invoice_id_is_unique(tx_sudo, invoice_id):
+        """Reject an invoice ID already linked to another transaction."""
+        other_tx = tx_sudo.env['payment.transaction'].sudo().search([
+            ('id', '!=', tx_sudo.id),
+            ('provider_code', '=', 'btcpayserver'),
+            '|',
+            ('btcpay_invoiceId', '=', invoice_id),
+            ('provider_reference', '=', invoice_id),
+        ], limit=1)
+        if other_tx:
+            raise ValidationError(_(
+                "BTCPay: The invoice is already linked to another transaction."
+            ))
+
+    @classmethod
+    def _validate_invoice_binding(
+            cls, tx_sudo, incoming_invoice_id, incoming_order_id, fetched_invoice):
+        """Bind the untrusted IPN payload to one authenticated invoice and transaction."""
+        if not isinstance(fetched_invoice, dict):
+            raise ValidationError(_("BTCPay: Received an invalid invoice response."))
+
+        fetched_invoice_id = fetched_invoice.get('id')
+        fetched_order_id = fetched_invoice.get('orderId')
+        if not (
+            incoming_invoice_id
+            and incoming_invoice_id == fetched_invoice_id
+            and incoming_invoice_id == tx_sudo.btcpay_invoiceId
+            and incoming_invoice_id == tx_sudo.provider_reference
+        ):
+            raise ValidationError(_(
+                "BTCPay: The notification invoice does not match the transaction."
+            ))
+        if not (
+            incoming_order_id
+            and incoming_order_id == fetched_order_id
+            and incoming_order_id == tx_sudo.reference
+        ):
+            raise ValidationError(_(
+                "BTCPay: The notification order does not match the transaction."
+            ))
+        cls._ensure_invoice_id_is_unique(tx_sudo, incoming_invoice_id)
+
+    @classmethod
+    def _find_transaction_by_invoice_id(cls, invoice_id):
+        """Find exactly one BTCPay transaction from its stored invoice ID."""
+        if not isinstance(invoice_id, str) or not invoice_id:
+            raise ValidationError(_("BTCPay: Missing invoice ID in notification data."))
+
+        txs_sudo = request.env['payment.transaction'].sudo().search([
+            ('provider_code', '=', 'btcpayserver'),
+            ('btcpay_invoiceId', '=', invoice_id),
+        ], limit=2)
+        if len(txs_sudo) != 1:
+            raise ValidationError(_(
+                "BTCPay: No unique transaction found matching the invoice ID."
+            ))
+        return txs_sudo
+
+    @staticmethod
+    def _validate_invoice_amount(tx_sudo, invoice):
+        """Reject reuse of an invoice with a different amount or currency."""
+        try:
+            amount = float(invoice.get('price'))
+        except (AttributeError, TypeError, ValueError):
+            amount = None
+        if (
+            amount is None
+            or invoice.get('currency') != tx_sudo.currency_id.name
+            or tx_sudo.currency_id.compare_amounts(amount, tx_sudo.amount) != 0
+        ):
+            raise ValidationError(_(
+                "BTCPay: The existing invoice amount or currency does not match the transaction."
+            ))
+
+    @classmethod
+    def _validate_existing_invoice(cls, tx_sudo, invoice_id, invoice):
+        """Validate a stored invoice before redirecting the customer to it."""
+        cls._validate_invoice_binding(
+            tx_sudo, invoice_id, tx_sudo.reference, invoice,
+        )
+        if not isinstance(invoice.get('status'), str) or not invoice['status']:
+            raise ValidationError(_("BTCPay: The existing invoice response is incomplete."))
+
+    @classmethod
+    def _validate_created_invoice(cls, tx_sudo, invoice):
+        """Validate a newly created invoice before storing its identity."""
+        if not isinstance(invoice, dict):
+            raise ValidationError(_("BTCPay: Received an invalid invoice response."))
+        invoice_id = invoice.get('id')
+        if (
+            not isinstance(invoice_id, str)
+            or not invoice_id
+            or not isinstance(invoice.get('url'), str)
+            or not invoice['url']
+            or invoice.get('orderId') not in (None, tx_sudo.reference)
+        ):
+            raise ValidationError(_("BTCPay: The created invoice response is incomplete."))
+        cls._ensure_invoice_id_is_unique(tx_sudo, invoice_id)
+
     @http.route(_checkout_url, type='http', auth='public', methods=['POST'],
                 csrf=False, website=True)
     def checkout(self, **data):
@@ -57,9 +175,10 @@ class BTCPayController(http.Controller):
         server-side and are never taken from the (client-controlled) request
         data, so a buyer cannot have an invoice created for a tampered amount.
         """
-        _logger.info("BTCPay: checkout request with data:\n%s", pprint.pformat(data))
+        _logger.info("BTCPay: checkout request for transaction %s", data.get('reference'))
         tx_sudo = request.env['payment.transaction'].sudo()._get_tx_from_notification_data(
             'btcpayserver', data)
+        self._lock_transaction(tx_sudo)
         if tx_sudo.state != 'draft':
             # Already processed (e.g. double submission): fall back to the
             # generic payment status page.
@@ -68,6 +187,31 @@ class BTCPayController(http.Controller):
         provider = tx_sudo.provider_id
         base_url = provider.get_base_url()
         client = self._btcpay_client(provider)
+
+        # A browser retry must not create a second payable invoice. Reuse the
+        # stored invoice while it remains payable. If it expired, the new ID is
+        # stored before the lock is released, so late notifications for the old
+        # invoice can no longer select this transaction.
+        if tx_sudo.btcpay_invoiceId:
+            existing_invoice = client.get_invoice(tx_sudo.btcpay_invoiceId)
+            self._validate_existing_invoice(
+                tx_sudo, tx_sudo.btcpay_invoiceId, existing_invoice,
+            )
+            if existing_invoice['status'].lower() != 'expired':
+                self._validate_invoice_amount(tx_sudo, existing_invoice)
+                if (
+                    not isinstance(existing_invoice.get('url'), str)
+                    or not existing_invoice['url']
+                ):
+                    raise ValidationError(_(
+                        "BTCPay: The existing invoice response is incomplete."
+                    ))
+                _logger.info(
+                    "BTCPay: reusing invoice %s for transaction %s",
+                    tx_sudo.btcpay_invoiceId, tx_sudo.reference,
+                )
+                return request.redirect(existing_invoice['url'], local=False)
+
         invoice = client.create_invoice({
             "price": tx_sudo.amount,
             "currency": tx_sudo.currency_id.name,
@@ -86,36 +230,54 @@ class BTCPayController(http.Controller):
                 "notify": False,
             },
         })
-        tx_sudo.btcpay_invoiceId = invoice.get('id')
+        self._validate_created_invoice(tx_sudo, invoice)
+        tx_sudo.write({
+            'btcpay_invoiceId': invoice['id'],
+            'provider_reference': invoice['id'],
+        })
         _logger.info("BTCPay: created invoice %s for transaction %s",
-                     invoice.get('id'), tx_sudo.reference)
+                     invoice['id'], tx_sudo.reference)
         return request.redirect(invoice['url'], local=False)
 
-    @http.route(_notify_url, type='json', auth='public', csrf=False)
+    @http.route(_notify_url, type='json', auth='public', methods=['POST'], csrf=False)
     def btcpay_ipn(self, **post):
         """ BTCPay IPN. """
         _logger.info('BTCPay: IPN received')
-        data = json.loads(request.httprequest.data)
-        _logger.info("%s", pprint.pformat(data))
         try:
-            notification_data = {
-                "reference": data['data']['orderId'],
-                "invoiceID": data['data']['id'],
-            }
-            # Check the origin and integrity of the notification: the invoice
-            # is fetched back from BTCPay (signed request), the posted payload
-            # is only used to locate the transaction.
-            tx_sudo = request.env['payment.transaction'].sudo()._get_tx_from_notification_data(
-                'btcpayserver', notification_data)
+            data = json.loads(request.httprequest.data)
+        except (json.JSONDecodeError, TypeError, UnicodeDecodeError):
+            _logger.warning("BTCPay: received malformed JSON notification data")
+            return ''
+
+        try:
+            ipn_data = data.get('data') if isinstance(data, dict) else None
+            if not isinstance(ipn_data, dict):
+                raise ValidationError(_("BTCPay: Invalid notification data."))
+            incoming_invoice_id = ipn_data.get('id')
+            incoming_order_id = ipn_data.get('orderId')
+
+            # Never use the untrusted order ID to select a transaction. The
+            # stored invoice ID is the lookup key.
+            tx_sudo = self._find_transaction_by_invoice_id(incoming_invoice_id)
             client = self._btcpay_client(tx_sudo.provider_id)
 
-            fetched_invoice = client.get_invoice(notification_data['invoiceID'])
-            _logger.info('BTCPay: fetched invoice = %s', pprint.pformat(fetched_invoice))
+            # Fetching through the authenticated API establishes the invoice's
+            # current state. Lock afterwards and re-check the stored ID so a
+            # concurrent checkout cannot replace it between lookup and use.
+            fetched_invoice = client.get_invoice(incoming_invoice_id)
+            self._lock_transaction(tx_sudo)
+            self._validate_invoice_binding(
+                tx_sudo, incoming_invoice_id, incoming_order_id, fetched_invoice,
+            )
+            _logger.info(
+                "BTCPay: verified invoice %s with status %s for transaction %s",
+                fetched_invoice.get('id'), fetched_invoice.get('status'), tx_sudo.reference,
+            )
 
             notification_data = {
-                "reference": fetched_invoice.get('orderId'),
+                "reference": tx_sudo.reference,
                 "status": fetched_invoice.get('status'),
-                "invoiceID": fetched_invoice.get('id'),
+                "invoiceID": incoming_invoice_id,
                 "txid": fetched_invoice.get('url'),
                 # Settled amount and currency, verified against the transaction
                 # before it is set done.
@@ -125,8 +287,8 @@ class BTCPayController(http.Controller):
 
             # Handle the notification data
             tx_sudo._handle_notification_data('btcpayserver', notification_data)
-        except ValidationError:  # Acknowledge the notification to avoid getting spammed
-            _logger.exception("Unable to handle the notification data; skipping to acknowledge")
+        except ValidationError as error:  # Acknowledge rejected notifications without retries.
+            _logger.warning("BTCPay: rejected notification: %s", error)
         return ''
 
     @http.route(_return_url, type='http', auth="public", methods=['GET'],