[FIX] Reject Internal MPP Melt Quote Requests (#697)

* fix * fix the fix * make sure the mpp is supported before testing * adjust message --------- Co-authored-by: callebtc <[email protected]>
cashubtc · Jan 29, 2025 · e9952e5 · e9952e5
1 parent 320c700
commit e9952e5
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diff --git a/cashu/mint/ledger.py b/cashu/mint/ledger.py
@@ -668,12 +668,16 @@ async def melt_quote(
         # and therefore respond with internal transaction fees (0 for now)
         mint_quote = await self.crud.get_mint_quote(request=request, db=self.db)
         if mint_quote and mint_quote.unit == melt_quote.unit:
+            # check if the melt quote is partial and error if it is.
+            # it's just not possible to handle this case
+            if melt_quote.is_mpp:
+                raise TransactionError("internal mpp not allowed.")
             payment_quote = self.create_internal_melt_quote(mint_quote, melt_quote)
         else:
             # not internal
             # verify that the backend supports mpp if the quote request has an amount
             if melt_quote.is_mpp and not self.backends[method][unit].supports_mpp:
-                raise TransactionError("backend does not support mpp")
+                raise TransactionError("backend does not support mpp.")
             # get payment quote by backend
             payment_quote = await self.backends[method][unit].get_payment_quote(
                 melt_quote=melt_quote

diff --git a/tests/test_wallet_regtest_mpp.py b/tests/test_wallet_regtest_mpp.py
@@ -11,6 +11,7 @@
 from cashu.wallet.wallet import Wallet
 from tests.conftest import SERVER_ENDPOINT
 from tests.helpers import (
+    assert_err,
     get_real_invoice,
     is_fake,
     partial_pay_real_invoice,
@@ -139,3 +140,19 @@ async def pay_mpp(amount: int, proofs: List[Proof], delay: float = 0.0):
     await asyncio.sleep(2)
 
     assert wallet.balance <= 384 - 64
+
+
+@pytest.mark.asyncio
+@pytest.mark.skipif(is_fake, reason="only regtest")
+async def test_regtest_internal_mpp_melt_quotes(wallet: Wallet, ledger: Ledger):
+    # make sure that mpp is supported by the bolt11-sat backend
+    if not ledger.backends[Method["bolt11"]][wallet.unit].supports_mpp:
+        pytest.skip("backend does not support mpp")
+
+    # create a mint quote
+    mint_quote = await wallet.request_mint(128)
+
+    # try and create a multi-part melt quote
+    await assert_err(
+        wallet.melt_quote(mint_quote.request, 100), "internal mpp not allowed"
+    )