Allow flexible derivation scheme for the store

BTCPayServer.Tests/TestAccount.cs

@@ -45,9 +45,9 @@ namespace BTCPayServer.Tests
 
 			await store.UpdateStore(StoreId, new StoreViewModel()
 			{
-				ExtPubKey = extKey.Neuter().ToString() + "-[legacy]",
+				DerivationScheme = extKey.Neuter().ToString() + "-[legacy]",
 				SpeedPolicy = SpeedPolicy.MediumSpeed
-			});
+			}, "Save");
 			Assert.IsType<ViewResult>(await store.RequestPairing(pairingCode.ToString()));
 			await store.Pair(pairingCode.ToString(), StoreId);
 		}

BTCPayServer/Controllers/StoresController.cs

@@ -10,6 +10,7 @@ using Microsoft.AspNetCore.Identity;
 using Microsoft.AspNetCore.Mvc;
 using NBitcoin;
 using NBitpayClient;
+using NBXplorer.DerivationStrategy;
 using System;
 using System.Collections.Generic;
 using System.Linq;
@@ -28,6 +29,7 @@ namespace BTCPayServer.Controllers
 			UserManager<ApplicationUser> userManager,
 			AccessTokenController tokenController,
 			BTCPayWallet wallet,
+			Network network,
 			IHostingEnvironment env)
 		{
 			_Repo = repo;
@@ -36,7 +38,9 @@ namespace BTCPayServer.Controllers
 			_TokenController = tokenController;
 			_Wallet = wallet;
 			_Env = env;
+			_Network = network;
 		}
+		Network _Network;
 		BTCPayWallet _Wallet;
 		AccessTokenController _TokenController;
 		StoreRepository _Repo;
@@ -106,7 +110,7 @@ namespace BTCPayServer.Controllers
 			vm.StoreName = store.StoreName;
 			vm.StoreWebsite = store.StoreWebsite;
 			vm.SpeedPolicy = store.SpeedPolicy;
-			vm.ExtPubKey = store.DerivationStrategy;
+			vm.DerivationScheme = store.DerivationStrategy;
 			vm.StatusMessage = StatusMessage;
 			return View(vm);
 		}
@@ -114,7 +118,7 @@ namespace BTCPayServer.Controllers
 		[HttpPost]
 		[ValidateAntiForgeryToken]
 		[Route("{storeId}")]
-		public async Task<IActionResult> UpdateStore(string storeId, StoreViewModel model)
+		public async Task<IActionResult> UpdateStore(string storeId, StoreViewModel model, string command)
 		{
 			if(!ModelState.IsValid)
 			{
@@ -124,6 +128,8 @@ namespace BTCPayServer.Controllers
 			if(store == null)
 				return NotFound();
 
+			if(command == "Save")
+			{
 				bool needUpdate = false;
 				if(store.SpeedPolicy != model.SpeedPolicy)
 				{
@@ -141,17 +147,17 @@ namespace BTCPayServer.Controllers
 					store.StoreWebsite = model.StoreWebsite;
 				}
 
-			if(store.DerivationStrategy != model.ExtPubKey)
+				if(store.DerivationStrategy != model.DerivationScheme)
 				{
 					needUpdate = true;
 					try
 					{
-					await _Wallet.TrackAsync(model.ExtPubKey);
+						await _Wallet.TrackAsync(model.DerivationScheme);
-					store.DerivationStrategy = model.ExtPubKey;
+						store.DerivationStrategy = model.DerivationScheme;
 					}
 					catch
 					{
-					ModelState.AddModelError(nameof(model.ExtPubKey), "Invalid Derivation Scheme");
+						ModelState.AddModelError(nameof(model.DerivationScheme), "Invalid Derivation Scheme");
 						return View(model);
 					}
 				}
@@ -167,6 +173,20 @@ namespace BTCPayServer.Controllers
 					storeId = storeId
 				});
 			}
+			else
+			{
+				var facto = new DerivationStrategyFactory(_Network);
+				var scheme = facto.Parse(model.DerivationScheme);
+				var line = scheme.GetLineFor(DerivationFeature.Deposit);
+
+				for(int i = 0; i < 10; i++)
+				{
+					var address = line.Derive((uint)i);
+					model.AddressSamples.Add((line.Path.Derive((uint)i).ToString(), address.ScriptPubKey.GetDestinationAddress(_Network).ToString()));
+				}
+				return View(model);
+			}
+		}
 
 		[HttpGet]
 		[Route("{storeId}/Tokens")]

BTCPayServer/Models/StoreViewModels/StoreViewModel.cs

@@ -27,8 +27,8 @@ namespace BTCPayServer.Models.StoreViewModels
 			set;
 		}
 
-		[ExtPubKeyValidator]
+		[DerivationStrategyValidator]
-		public string ExtPubKey
+		public string DerivationScheme
 		{
 			get; set;
 		}
@@ -39,6 +39,11 @@ namespace BTCPayServer.Models.StoreViewModels
 			get; set;
 		}
 
+		public List<(string KeyPath, string Address)> AddressSamples
+		{
+			get; set;
+		} = new List<(string KeyPath, string Address)>();
+
 		public string StatusMessage
 		{
 			get; set;

BTCPayServer/Validations/DerivationStrategyValidatorAttribute.cs

@@ -1,4 +1,5 @@
 using NBitcoin;
+using NBXplorer.DerivationStrategy;
 using System;
 using System.Collections.Generic;
 using System.ComponentModel.DataAnnotations;
@@ -6,7 +7,7 @@ using System.Text;
 
 namespace BTCPayServer.Validations
 {
-    public class ExtPubKeyValidatorAttribute :  ValidationAttribute
+    public class DerivationStrategyValidatorAttribute :  ValidationAttribute
 	{
 		protected override ValidationResult IsValid(object value, ValidationContext validationContext)
 		{
@@ -19,7 +20,7 @@ namespace BTCPayServer.Validations
 				return new ValidationResult("No Network specified");
 			try
 			{
-				new BitcoinExtPubKey((string)value, network);
+				new DerivationStrategyFactory(network).Parse((string)value);
 				return ValidationResult.Success;
 			}
 			catch(Exception ex)

BTCPayServer/Views/Stores/UpdateStore.cshtml

@@ -36,11 +36,77 @@
 				<span asp-validation-for="SpeedPolicy" class="text-danger"></span>
 			</div>
 			<div class="form-group">
-				<label asp-for="ExtPubKey"></label>
+				<h5>Derivation Scheme</h5>
-				<input asp-for="ExtPubKey" class="form-control" />
+				@if(Model.AddressSamples.Count == 0)
-				<span asp-validation-for="ExtPubKey" class="text-danger"></span>
+				{
+					<span>The DerivationScheme represents the destination of the funds received by your invoice. It is generated by your wallet software. Please, verify that you are generating the right addresses by clicking on 'Check ExtPubKey'</span>
+				}
 			</div>
-			<button type="submit" class="btn btn-default">Save</button>
+			<div class="form-group">
+				<input asp-for="DerivationScheme" class="form-control" />
+				<span asp-validation-for="DerivationScheme" class="text-danger"></span>
+			</div>
+			<div class="form-group">
+				@if(Model.AddressSamples.Count == 0)
+				{
+					<table class="table">
+						<thead class="thead-inverse">
+							<tr>
+								<th>Address type</th>
+								<th>Example</th>
+							</tr>
+						</thead>
+						<tbody>
+							<tr>
+								<td>P2WPKH</td>
+								<td>xpub</td>
+							</tr>
+							<tr>
+								<td>P2SH-P2WPKH</td>
+								<td>xpub-[p2sh]</td>
+							</tr>
+							<tr>
+								<td>P2SH</td>
+								<td>xpub-[legacy]</td>
+							</tr>
+							<tr>
+								<td>Multi-sig P2WSH</td>
+								<td>2-of-xpub1-xpub2</td>
+							</tr>
+							<tr>
+								<td>Multi-sig P2SH-P2WSH</td>
+								<td>2-of-xpub1-xpub2-[p2sh]</td>
+							</tr>
+							<tr>
+								<td>Multi-sig P2SH</td>
+								<td>2-of-xpub1-xpub2-[legacy]</td>
+							</tr>
+						</tbody>
+					</table>
+				}
+				else
+				{
+					<table class="table">
+						<thead class="thead-inverse">
+							<tr>
+								<th>Key path</th>
+								<th>Address</th>
+							</tr>
+						</thead>
+						<tbody>
+							@foreach(var sample in Model.AddressSamples)
+							{
+								<tr>
+									<td>@sample.KeyPath</td>
+									<td>@sample.Address</td>
+								</tr>
+							}
+						</tbody>
+					</table>
+				}
+			</div>
+			<button name="command" type="submit" class="btn btn-success" value="Save">Save</button>
+			<button name="command" type="submit" class="btn btn-default" value="Check">Check ExtPubKey</button>
 		</form>
 	</div>
 </div>