Fix bug: Paying a lightning invoice might miss 1 satoshi due to rounding error

BTCPayServer/BTCPayServer.csproj

@@ -2,7 +2,7 @@
   <PropertyGroup>
     <OutputType>Exe</OutputType>
     <TargetFramework>netcoreapp2.0</TargetFramework>
-		<Version>1.0.1.49</Version>
+		<Version>1.0.1.50</Version>
     <NoWarn>NU1701,CA1816,CA1308,CA1810,CA2208</NoWarn>
   </PropertyGroup>
   <ItemGroup>

BTCPayServer/Extensions.cs

@@ -30,6 +30,19 @@ namespace BTCPayServer
 {
     public static class Extensions
     {
+        public static decimal RoundUp(decimal value, int precision)
+        {
+            for (int i = 0; i < precision; i++)
+            {
+                value = value * 10m;
+            }
+            value = Math.Ceiling(value);
+            for (int i = 0; i < precision; i++)
+            {
+                value = value / 10m;
+            }
+            return value;
+        }
         public static PaymentMethodId GetpaymentMethodId(this InvoiceCryptoInfo info)
         {
             return new PaymentMethodId(info.CryptoCode, Enum.Parse<PaymentTypes>(info.PaymentType));

BTCPayServer/Payments/Bitcoin/NBXplorerListener.cs

@@ -160,7 +160,8 @@ namespace BTCPayServer.Payments.Bitcoin
                                             if (!alreadyExist)
                                             {
                                                 var payment = await _InvoiceRepository.AddPayment(invoice.Id, DateTimeOffset.UtcNow, paymentData, network.CryptoCode);
-                                                await ReceivedPayment(wallet, invoice.Id, payment, evt.DerivationStrategy);
+                                                if(payment != null)
+                                                    await ReceivedPayment(wallet, invoice.Id, payment, evt.DerivationStrategy);
                                             }
                                             else
                                             {
@@ -330,7 +331,8 @@ namespace BTCPayServer.Payments.Bitcoin
                     var paymentData = new BitcoinLikePaymentData(coin.Coin, transaction.Transaction.RBF);
                     var payment = await _InvoiceRepository.AddPayment(invoice.Id, coin.Timestamp, paymentData, network.CryptoCode).ConfigureAwait(false);
                     alreadyAccounted.Add(coin.Coin.Outpoint);
-                    invoice = await ReceivedPayment(wallet, invoice.Id, payment, strategy);
+                    if (payment != null)
+                        invoice = await ReceivedPayment(wallet, invoice.Id, payment, strategy);
                     totalPayment++;
                 }
             }

BTCPayServer/Payments/Lightning/ChargeListener.cs

@@ -163,12 +163,13 @@ namespace BTCPayServer.Payments.Lightning
 
         private async Task AddPayment(BTCPayNetwork network, ChargeInvoice notification, ListenedInvoice listenedInvoice)
         {
-            await _InvoiceRepository.AddPayment(listenedInvoice.InvoiceId, notification.PaidAt.Value, new LightningLikePaymentData()
+            var payment = await _InvoiceRepository.AddPayment(listenedInvoice.InvoiceId, notification.PaidAt.Value, new LightningLikePaymentData()
             {
                 BOLT11 = notification.PaymentRequest,
                 Amount = notification.MilliSatoshi
             }, network.CryptoCode, accounted: true);
-            _Aggregator.Publish(new InvoiceEvent(listenedInvoice.InvoiceId, 1002, "invoice_receivedPayment"));
+            if(payment != null)
+                _Aggregator.Publish(new InvoiceEvent(listenedInvoice.InvoiceId, 1002, "invoice_receivedPayment"));
         }
 
         private static ChargeClient GetChargeClient(LightningSupportedPaymentMethod supportedPaymentMethod, BTCPayNetwork network)

BTCPayServer/Payments/Lightning/LightningLikePaymentHandler.cs

@@ -21,7 +21,7 @@ namespace BTCPayServer.Payments.Lightning
         public override async Task<IPaymentMethodDetails> CreatePaymentMethodDetails(LightningSupportedPaymentMethod supportedPaymentMethod, PaymentMethod paymentMethod, BTCPayNetwork network)
         {
             var invoice = paymentMethod.ParentEntity;
-            var due = invoice.ProductInformation.Price / paymentMethod.Rate;
+            var due = Extensions.RoundUp(invoice.ProductInformation.Price / paymentMethod.Rate, 8);
             var client = GetClient(supportedPaymentMethod, network);
             var expiry = invoice.ExpirationTime - DateTimeOffset.UtcNow;
             var lightningInvoice = await client.CreateInvoiceAsync(new CreateInvoiceRequest()

BTCPayServer/Services/Invoices/InvoiceEntity.cs

@@ -646,8 +646,9 @@ namespace BTCPayServer.Services.Invoices
             var paid = 0m;
             var cryptoPaid = 0.0m;
 
+            int precision = 8;
             var paidTxFee = 0m;
-            bool paidEnough = paid >= RoundUp(totalDue, 8);
+            bool paidEnough = paid >= Extensions.RoundUp(totalDue, precision);
             int txRequired = 0;
             var payments =
                 ParentEntity.GetPayments()
@@ -662,7 +663,7 @@ namespace BTCPayServer.Services.Invoices
                         totalDue += txFee;
                         paidTxFee += txFee;
                     }
-                    paidEnough |= paid >= RoundUp(totalDue, 8);
+                    paidEnough |= paid >= Extensions.RoundUp(totalDue, precision);
                     if (GetId() == _.GetPaymentMethodId())
                     {
                         cryptoPaid += _.GetCryptoPaymentData().GetValue();
@@ -681,7 +682,7 @@ namespace BTCPayServer.Services.Invoices
                 paidTxFee += GetTxFee();
             }
 
-            accounting.TotalDue = Money.Coins(RoundUp(totalDue, 8));
+            accounting.TotalDue = Money.Coins(Extensions.RoundUp(totalDue, precision));
             accounting.Paid = Money.Coins(paid);
             accounting.TxRequired = txRequired;
             accounting.CryptoPaid = Money.Coins(cryptoPaid);
@@ -691,20 +692,6 @@ namespace BTCPayServer.Services.Invoices
             return accounting;
         }
 
-        private static decimal RoundUp(decimal value, int precision)
-        {
-            for (int i = 0; i < precision; i++)
-            {
-                value = value * 10m;
-            }
-            value = Math.Ceiling(value);
-            for (int i = 0; i < precision; i++)
-            {
-                value = value / 10m;
-            }
-            return value;
-        }
-
         private decimal GetTxFee()
         {
             var method = GetPaymentMethodDetails();

BTCPayServer/Services/Invoices/InvoiceRepository.cs

@@ -461,6 +461,15 @@ namespace BTCPayServer.Services.Invoices
             AddToTextSearch(invoiceId, addresses.Select(a => a.ToString()).ToArray());
         }
 
+        /// <summary>
+        /// Add a payment to an invoice
+        /// </summary>
+        /// <param name="invoiceId"></param>
+        /// <param name="date"></param>
+        /// <param name="paymentData"></param>
+        /// <param name="cryptoCode"></param>
+        /// <param name="accounted"></param>
+        /// <returns>The PaymentEntity or null if already added</returns>
         public async Task<PaymentEntity> AddPayment(string invoiceId, DateTimeOffset date, CryptoPaymentData paymentData, string cryptoCode, bool accounted = false)
         {
             using (var context = _ContextFactory.CreateContext())
@@ -486,7 +495,11 @@ namespace BTCPayServer.Services.Invoices
 
                 context.Payments.Add(data);
 
-                await context.SaveChangesAsync().ConfigureAwait(false);
+                try
+                {
+                    await context.SaveChangesAsync().ConfigureAwait(false);
+                }
+                catch(DbUpdateException) { return null; } // Already exists
                 AddToTextSearch(invoiceId, paymentData.GetSearchTerms());
                 return entity;
             }