feat: preimages for incoming payments, fundingsource saves preimage on create_invoice (#3085)

Co-authored-by: Vlad Stan <stan.v.vlad@gmail.com>

lnbits/wallets/lndgrpc.py

@@ -1,6 +1,6 @@
 import asyncio
 import base64
-import hashlib
+from hashlib import sha256
 from os import environ
 from typing import AsyncGenerator, Dict, Optional
 
@@ -12,7 +12,7 @@ import lnbits.wallets.lnd_grpc_files.lightning_pb2_grpc as lnrpc
 import lnbits.wallets.lnd_grpc_files.router_pb2 as router
 import lnbits.wallets.lnd_grpc_files.router_pb2_grpc as routerrpc
 from lnbits.settings import settings
-from lnbits.utils.crypto import AESCipher
+from lnbits.utils.crypto import AESCipher, random_secret_and_hash
 
 from .base import (
     InvoiceResponse,
@@ -139,22 +139,37 @@ class LndWallet(Wallet):
         if description_hash:
             data["description_hash"] = description_hash
         elif unhashed_description:
-            data["description_hash"] = hashlib.sha256(
-                unhashed_description
-            ).digest()  # as bytes directly
+            data["description_hash"] = sha256(unhashed_description).digest()
 
+        preimage = kwargs.get("preimage")
+        if preimage:
+            payment_hash = sha256(preimage.encode()).hexdigest()
+        else:
+            preimage, payment_hash = random_secret_and_hash()
+
+        data["r_hash"] = bytes.fromhex(payment_hash)
+        data["r_preimage"] = bytes.fromhex(preimage)
         try:
             req = ln.Invoice(**data)
             resp = await self.rpc.AddInvoice(req)
+            # response model
+            # {
+            #    "r_hash": <bytes>,
+            #    "payment_request": <string>,
+            #    "add_index": <uint64>,
+            #    "payment_addr": <bytes>,
+            # }
         except Exception as exc:
             logger.warning(exc)
-            error_message = str(exc)
-            return InvoiceResponse(ok=False, error_message=error_message)
+            return InvoiceResponse(ok=False, error_message=str(exc))
 
         checking_id = bytes_to_hex(resp.r_hash)
         payment_request = str(resp.payment_request)
         return InvoiceResponse(
-            ok=True, checking_id=checking_id, payment_request=payment_request
+            ok=True,
+            checking_id=checking_id,
+            payment_request=payment_request,
+            preimage=preimage,
         )
 
     async def pay_invoice(self, bolt11: str, fee_limit_msat: int) -> PaymentResponse:
@@ -197,16 +212,18 @@ class LndWallet(Wallet):
             fee_msat = -resp.htlcs[-1].route.total_fees_msat
             preimage = resp.payment_preimage
             checking_id = resp.payment_hash
+            return PaymentResponse(
+                ok=True, checking_id=checking_id, fee_msat=fee_msat, preimage=preimage
+            )
         elif statuses[resp.status] is False:
             error_message = failure_reasons[resp.failure_reason]
-
-        return PaymentResponse(
-            ok=statuses[resp.status],
-            checking_id=checking_id,
-            fee_msat=fee_msat,
-            preimage=preimage,
-            error_message=error_message,
-        )
+            return PaymentResponse(ok=False, error_message=error_message)
+        else:
+            return PaymentResponse(
+                ok=None,
+                checking_id=checking_id,
+                error_message="Payment in flight or non-existant.",
+            )
 
     async def get_invoice_status(self, checking_id: str) -> PaymentStatus:
         try:
@@ -217,10 +234,8 @@ class LndWallet(Wallet):
                 raise ValueError
 
             resp = await self.rpc.LookupInvoice(ln.PaymentHash(r_hash=r_hash))
-
-            # todo: where is the FAILED status
             if resp.settled:
-                return PaymentSuccessStatus()
+                return PaymentSuccessStatus(preimage=resp.r_preimage.hex())
 
             return PaymentPendingStatus()
         except grpc.RpcError as exc: