Give more information to the user if payjoin fails

BTCPayServer/Controllers/WalletsController.PSBT.cs

@@ -8,6 +8,7 @@ using System.Threading.Tasks;
 using BTCPayServer.ModelBinders;
 using BTCPayServer.Models;
 using BTCPayServer.Models.WalletViewModels;
+using BTCPayServer.Services;
 using Microsoft.AspNetCore.Mvc;
 using NBitcoin;
 using NBXplorer;
@@ -144,25 +145,15 @@ namespace BTCPayServer.Controllers
             }
         }
 
-        private async Task<PSBT> TryGetPayjoinProposedTX(string bpu, PSBT psbt, DerivationSchemeSettings derivationSchemeSettings, BTCPayNetwork btcPayNetwork, CancellationToken cancellationToken)
+        private async Task<PSBT> GetPayjoinProposedTX(string bpu, PSBT psbt, DerivationSchemeSettings derivationSchemeSettings, BTCPayNetwork btcPayNetwork, CancellationToken cancellationToken)
-        {
-            if (!string.IsNullOrEmpty(bpu) && Uri.TryCreate(bpu, UriKind.Absolute, out var endpoint))
         {
+            if (string.IsNullOrEmpty(bpu) || !Uri.TryCreate(bpu, UriKind.Absolute, out var endpoint))
+                throw new InvalidOperationException("No payjoin url available");
             var cloned = psbt.Clone();
             cloned = cloned.Finalize();
             await _broadcaster.Schedule(DateTimeOffset.UtcNow + TimeSpan.FromMinutes(1.0), cloned.ExtractTransaction(), btcPayNetwork);
-                try
-                {
             return await _payjoinClient.RequestPayjoin(endpoint, derivationSchemeSettings, cloned, cancellationToken);
         }
-                catch (Exception)
-                {
-                    return null;
-                }
-                
-            }
-            return null;
-        }
         
         [HttpGet]
         [Route("{walletId}/psbt/ready")]
@@ -321,22 +312,11 @@ namespace BTCPayServer.Controllers
             switch (command)
             {
                 case "payjoin":
-                    var proposedPayjoin =await 
+                    string error = null;
-                        TryGetPayjoinProposedTX(vm.PayJoinEndpointUrl, psbt, derivationSchemeSettings, network, cancellationToken);
+                    try
-                    if (proposedPayjoin == null)
                     {
-                        //we possibly exposed the tx to the receiver, so we need to broadcast straight away
+                        var proposedPayjoin = await GetPayjoinProposedTX(vm.PayJoinEndpointUrl, psbt,
-                        TempData.SetStatusMessageModel(new StatusMessageModel()
+                            derivationSchemeSettings, network, cancellationToken);
-                        {
-                            Severity = StatusMessageModel.StatusSeverity.Warning,
-                            AllowDismiss = false,
-                            Html = $"The payjoin transaction could not be created. The original transaction was broadcast instead."
-                        });
-                        return await WalletPSBTReady(walletId, vm, "broadcast");
-                    }
-                    else
-                    {
-                        
                         try
                         {
                             var extKey = ExtKey.Parse(vm.SigningKey, network.NBitcoinNetwork);
@@ -345,20 +325,53 @@ namespace BTCPayServer.Controllers
                                 RootedKeyPath.Parse(vm.SigningKeyPath));
                             vm.PSBT = proposedPayjoin.ToBase64();
                             vm.OriginalPSBT = psbt.ToBase64();
+                            proposedPayjoin.Finalize();
+                            TempData.SetStatusMessageModel(new StatusMessageModel()
+                            {
+                                Severity = StatusMessageModel.StatusSeverity.Success,
+                                AllowDismiss = false,
+                                Html = $"The payjoin transaction has been successfully broadcasted ({proposedPayjoin.ExtractTransaction().GetHash()})"
+                            });
                             return await WalletPSBTReady(walletId, vm, "broadcast");
                         }
                         catch (Exception)
                         {
                             TempData.SetStatusMessageModel(new StatusMessageModel()
                             {
-                                Severity = StatusMessageModel.StatusSeverity.Info,
+                                Severity = StatusMessageModel.StatusSeverity.Warning,
                                 AllowDismiss = false,
                                 Html =
-                                    $"This transaction has been coordinated between the receiver and you to create a <a href='https://en.bitcoin.it/wiki/PayJoin' target='_blank'>payjoin transaction</a> by adding inputs from the receiver. The amount being sent may appear higher but is in fact the same"
+                                    $"This transaction has been coordinated between the receiver and you to create a <a href='https://en.bitcoin.it/wiki/PayJoin' target='_blank'>payjoin transaction</a> by adding inputs from the receiver.<br/>" +
+                                    $"The amount being sent may appear higher but is in fact almost same.<br/><br/>" +
+                                    $"If you cancel refuse to sign this transaction, the payment will proceed without payjoin"
                             });
                             return ViewVault(walletId, proposedPayjoin, vm.PayJoinEndpointUrl, psbt);
                         }
                     }
+                    catch (PayjoinReceiverException ex)
+                    {
+                        error = $"The payjoin receiver could not complete the payjoin: {ex.Message}";
+                    }
+                    catch (PayjoinSenderException ex)
+                    {
+                        error = $"We rejected the receiver's payjoin proposal: {ex.Message}";
+                    }
+                    catch (Exception ex)
+                    {
+                        error = $"Unexpected payjoin error: {ex.Message}";
+                    }
+                    
+                    //we possibly exposed the tx to the receiver, so we need to broadcast straight away
+                    psbt.Finalize();
+                    TempData.SetStatusMessageModel(new StatusMessageModel()
+                    {
+                        Severity = StatusMessageModel.StatusSeverity.Warning,
+                        AllowDismiss = false,
+                        Html = $"The payjoin transaction could not be created.<br/>" +
+                               $"The original transaction was broadcasted instead. ({psbt.ExtractTransaction().GetHash()})<br/><br/>" +
+                               $"{error}"
+                    });
+                    return await WalletPSBTReady(walletId, vm, "broadcast");
                 case "broadcast" when !psbt.IsAllFinalized() && !psbt.TryFinalize(out var errors):
                     vm.SetErrors(errors);
                     return View(nameof(WalletPSBTReady),vm);
@@ -376,7 +389,7 @@ namespace BTCPayServer.Controllers
                                 {
                                     Severity = StatusMessageModel.StatusSeverity.Warning,
                                     AllowDismiss = false,
-                                    Html = $"The payjoin transaction could not be broadcast.<br/>({broadcastResult.RPCCode} {broadcastResult.RPCCodeMessage} {broadcastResult.RPCMessage}).<br/>The transaction has been reverted back to its original format and has been broadcast."
+                                    Html = $"The payjoin transaction could not be broadcasted.<br/>({broadcastResult.RPCCode} {broadcastResult.RPCCodeMessage} {broadcastResult.RPCMessage}).<br/>The transaction has been reverted back to its original format and has been broadcast."
                                 });
                                 vm.PSBT = vm.OriginalPSBT;
                                 vm.OriginalPSBT = null;
@@ -392,6 +405,11 @@ namespace BTCPayServer.Controllers
                         vm.GlobalError = "Error while broadcasting: " + ex.Message;
                         return View(nameof(WalletPSBTReady),vm);
                     }
+
+                    if (!TempData.HasStatusMessage())
+                    {
+                        TempData[WellKnownTempData.SuccessMessage] = $"Transaction broadcasted successfully ({transaction.GetHash()})";
+                    }
                     return RedirectToWalletTransaction(walletId, transaction);
                 }
                 case "analyze-psbt":

BTCPayServer/Controllers/WalletsController.cs

@@ -869,17 +869,6 @@ namespace BTCPayServer.Controllers
                 var wallet = _walletProvider.GetWallet(network);
                 var derivationSettings = GetDerivationSchemeSettings(walletId);
                 wallet.InvalidateCache(derivationSettings.AccountDerivation);
-                if (TempData.GetStatusMessageModel() == null)
-                {
-                    TempData[WellKnownTempData.SuccessMessage] =
-                        $"Transaction broadcasted successfully ({transaction.GetHash()})";
-                }
-                else
-                {
-                    var statusMessageModel = TempData.GetStatusMessageModel();
-                    statusMessageModel.Message += $" ({transaction.GetHash()})";
-                    TempData.SetStatusMessageModel(statusMessageModel);
-                }
             }
             return RedirectToAction(nameof(WalletTransactions), new { walletId = walletId.ToString() });
         }