bolt12: don't use path_id, instead generate offer_id and store in offer_metadata

Author: accumulator

electrum/lnworker.py

@@ -3829,15 +3829,16 @@ def get_forwarding_failure(self, payment_key: str) -> Tuple[Optional[bytes], Opt
     def on_bolt12_invoice_request(self, recipient_data: dict, payload: dict):
         # match to offer
         self.logger.debug(f'on_bolt12_invoice_request: {recipient_data=} {payload=}')
-        offer_id = recipient_data['path_id']['data']
-        offer = self.wallet.get_offer(offer_id)
-        if offer is None:
-            self.logger.warning('no matching offer for invoice_request')
-            return
 
         invreq_tlv = payload['invoice_request']['invoice_request']
         invreq = bolt12.decode_invoice_request(invreq_tlv)
         self.logger.info(f'invoice_request: {invreq=}')
+
+        offer_id = invreq.get('offer_metadata', {}).get('data')
+        offer = self.wallet.get_offer(offer_id)
+        if offer is None:
+            self.logger.warning('no matching offer for invoice_request')
+            return
         self.logger.debug(f'invoice_request for {offer=}')
 
         # two scenarios:

electrum/wallet.py

@@ -3132,12 +3132,14 @@ def create_offer(self, amount, memo, expiry):
         assert self.has_lightning(), 'not a lightning wallet'
         assert self.has_channels(), 'no channels'
 
-        path_id = os.urandom(32)
+        path_id = os.urandom(32)  # TODO: move path_id gen get_blinded_reply_paths, unique per path
         reply_paths = get_blinded_reply_paths(self.lnworker, path_id, max_paths=1)  # max 1 for now
         if not len(reply_paths):
             raise Exception('No suitable channels')
 
+        offer_id = os.urandom(16)
         offer = {
+            'offer_metadata': {'data': offer_id},
             'offer_description': {'description': memo},
             'offer_issuer_id': {'id': self.lnworker.node_keypair.pubkey},
             'offer_paths': {'paths': reply_paths},
@@ -3149,9 +3151,9 @@ def create_offer(self, amount, memo, expiry):
         if expiry:
             now = int(time.time())
             offer['offer_absolute_expiry'] = {'seconds_from_epoch': now + expiry}
-        self._offers[path_id] = offer
+        self._offers[offer_id] = offer
 
-        return path_id
+        return offer_id
 
     def get_offer(self, key) -> Optional[dict]:
         return self._offers.get(key)