SP-1022 - C# Kiosk Demo: Add HMAC verification

CsharpKioskDemoDotnet.IntegrationTests/AbstractUiIntegrationTest.cs

@@ -69,7 +69,8 @@ protected Task<HttpResponseMessage> Get(string url)
 
     protected Task<HttpResponseMessage> Post(
         string url,
-        string jsonRequest
+        string jsonRequest,
+        Dictionary<string, string>? headers = null
     )
     {
         var httpContent = new StringContent(
@@ -78,6 +79,13 @@ string jsonRequest
             "application/json"
         );
 
+        if (headers != null) {
+            foreach(var item in headers)
+            {
+                httpContent.Headers.Add(item.Key, item.Value);
+            }
+        }
+
         return _client.PostAsync(url, httpContent);
     }
 
@@ -106,4 +114,4 @@ public void Info(LogCode code, string message, Dictionary<string, object?> conte
     public void Error(LogCode code, string message, Dictionary<string, object?> context)
     {
     }
-}
+}

CsharpKioskDemoDotnet.IntegrationTests/Src/Invoice/Infrastructure/Ui/UpdateInvoice/UpdateInvoiceIntegrationTest.cs

@@ -19,7 +19,14 @@ public async Task POST_InvoiceExistsForUuidAndUpdateDataAreValid_UpdateInvoice()
         var updateDataJson = UnitTest.GetDataFromFile("updateData.json");
 
         // when
-        var result = await Post("/invoices/" + invoice.Uuid, updateDataJson);
+        var result = await Post(
+            "/invoices/" + invoice.Uuid,
+            updateDataJson,
+            new Dictionary<string, string>
+            {
+                { "x-signature", "bKGK0WgsFfMSEg4fpik9+OdjYrYNA1E99kI1QJmbfKw=" }
+            }
+        );
 
         // then
         result.EnsureSuccessStatusCode();
@@ -37,7 +44,14 @@ public async Task POST_InvoiceDoesNotExistsForUuid_DoNotUpdateInvoice()
         var updateDataJson = UnitTest.GetDataFromFile("updateData.json");
 
         // when
-        var result = await Post("/invoices/12312412", updateDataJson);
+        var result = await Post(
+            "/invoices/12312412", 
+            updateDataJson,
+            new Dictionary<string, string>
+            {
+                { "x-signature", "bKGK0WgsFfMSEg4fpik9+OdjYrYNA1E99kI1QJmbfKw=" }
+            }
+        );
 
         // then
         UnitTest.Equals(
@@ -58,7 +72,14 @@ public async Task POST_UpdateDataAreInvalid_DoNotUpdateInvoice()
         var updateDataJson = UnitTest.GetDataFromFile("invalidUpdateData.json");
 
         // when
-        var result = await Post("/invoices/" + invoice.Uuid, updateDataJson);
+        var result = await Post(
+            "/invoices/" + invoice.Uuid, 
+            updateDataJson, 
+            new Dictionary<string, string>
+            {
+                { "x-signature", "16imUAXdJqur7yyQyDRRfcbPCeMPiuBFnNJVLlpi3hQ=" }
+            }
+        );
 
         // then
         UnitTest.Equals(
@@ -75,6 +96,31 @@ public async Task POST_UpdateDataAreInvalid_DoNotUpdateInvoice()
         );
     }
 
+    [Fact]
+    public async Task POST_WebhookSignatureInvalid_DoNotUpdateInvoice()
+    {
+        // given
+        var invoice = CreateInvoice();
+        var updateDataJson = UnitTest.GetDataFromFile("invalidUpdateData.json");
+
+        // when
+        var result = await Post(
+            "/invoices/" + invoice.Uuid, 
+            updateDataJson, 
+            new Dictionary<string, string>
+            {
+                { "x-signature", "randomsignature" }
+            }
+        );
+
+        // then
+        result.EnsureSuccessStatusCode();
+        UnitTest.Equals(
+            "new",
+            GetInvoiceRepository().FindById(invoice.Id).Status
+        );
+    }
+
     private CsharpKioskDemoDotnet.Invoice.Domain.Invoice CreateInvoice()
     {
         var invoiceJson = UnitTest.GetDataFromFile("invoice.json");
@@ -83,4 +129,4 @@ private CsharpKioskDemoDotnet.Invoice.Domain.Invoice CreateInvoice()
 
         return invoice;
     }
-}
+}

CsharpKioskDemoDotnet/Src/Invoice/Infrastructure/Features/Tasks/UpdateInvoice/WebhookVerifier.cs

@@ -0,0 +1,25 @@
+// Copyright 2023 BitPay.
+// All rights reserved.
+
+using System;
+using System.Security.Cryptography;
+using System.Text;
+
+namespace CsharpKioskDemoDotnet.Invoice.Infrastructure.Features.Tasks.UpdateInvoice;
+
+public class WebhookVerifier
+{
+    public bool Verify(string signingKey, string sigHeader, string webhookBody)
+    {
+        ArgumentNullException.ThrowIfNull(signingKey);
+        ArgumentNullException.ThrowIfNull(sigHeader);
+        ArgumentNullException.ThrowIfNull(webhookBody);
+
+        using var hmac = new HMACSHA256(Encoding.UTF8.GetBytes(signingKey));
+        byte[] signatureBytes = hmac.ComputeHash(Encoding.UTF8.GetBytes(webhookBody));
+        string calculated = Convert.ToBase64String(signatureBytes);
+        bool match = sigHeader.Equals(calculated, StringComparison.Ordinal);
+
+        return match;
+    }
+}

CsharpKioskDemoDotnet/Src/Invoice/Infrastructure/Ui/UpdateInvoice/HttpUpdateInvoice.cs

@@ -3,49 +3,88 @@
 
 using CsharpKioskDemoDotnet.Invoice.Application.Features.Tasks.UpdateInvoice;
 using CsharpKioskDemoDotnet.Invoice.Domain;
+using CsharpKioskDemoDotnet.Invoice.Infrastructure.Features.Tasks.UpdateInvoice;
 using CsharpKioskDemoDotnet.Shared;
+using CsharpKioskDemoDotnet.Shared.Infrastructure;
+using CsharpKioskDemoDotnet.Shared.Logger;
 
 using Microsoft.AspNetCore.Mvc;
+using Newtonsoft.Json;
+using System.Text;
+
+using ILogger = CsharpKioskDemoDotnet.Shared.Logger.ILogger;
 
 namespace CsharpKioskDemoDotnet.Invoice.Infrastructure.Ui.UpdateInvoice;
 
 public class HttpUpdateInvoice : Controller
 {
     private readonly Application.Features.Tasks.UpdateInvoice.UpdateInvoice _updateInvoice;
     private readonly IJsonToObjectConverter _jsonToObjectConverter;
+    private readonly WebhookVerifier _webhookVerifier;
+    private readonly IConfiguration _configuration;
+    private readonly ILogger _logger;
 
     public HttpUpdateInvoice(
         Application.Features.Tasks.UpdateInvoice.UpdateInvoice updateInvoice,
-        IJsonToObjectConverter jsonToObjectConverter
+        IJsonToObjectConverter jsonToObjectConverter,
+        WebhookVerifier webhookVerifier,
+        IConfiguration configuration,
+        ILogger logger
     )
     {
         _updateInvoice = updateInvoice;
         _jsonToObjectConverter = jsonToObjectConverter;
+        _webhookVerifier = webhookVerifier;
+        _configuration = configuration;
+        _logger = logger;
     }
 
     // POST: invoice/{uuid}
     [HttpPost("invoices/{uuid}")]
     public ActionResult Execute(
         string uuid,
-        [FromBody] Dictionary<string, object> body
+        [FromHeader(Name = "x-signature")] string signature
     )
     {
+        var token = _configuration["BitPay:Token"];
+        using StreamReader reader = new StreamReader(Request.Body, Encoding.UTF8);
+        var rawBody = reader.ReadToEndAsync().GetAwaiter().GetResult();
+
         ArgumentNullException.ThrowIfNull(uuid);
+        ArgumentNullException.ThrowIfNull(rawBody);
+        ArgumentNullException.ThrowIfNull(token);
+
+        var body = JsonConvert.DeserializeObject<Dictionary<string, object>>(rawBody);
+
         ArgumentNullException.ThrowIfNull(body);
-        try
-        {
-            _updateInvoice.Execute(uuid, GetData(body));
+
+        if (_webhookVerifier.Verify(token, signature, rawBody)) {
+            try
+            {
+                _updateInvoice.Execute(uuid, GetData(body));
+
+                return Ok();
+            }
+            catch (ValidationInvoiceUpdateDataFailedException exception)
+            {
+                return BadRequest(exception.Errors);
+            }
+            catch (InvoiceNotFoundException)
+            {
+                return NotFound();
+            }
+        } else {
+            _logger.Error(
+                LogCode.IpnSignatureVerificationFail,
+                "Webhook signature verification failed",
+                new Dictionary<string, object?>
+                {
+                    { "uuid", uuid }
+                }
+            );
 
             return Ok();
         }
-        catch (ValidationInvoiceUpdateDataFailedException exception)
-        {
-            return BadRequest(exception.Errors);
-        }
-        catch (InvoiceNotFoundException)
-        {
-            return NotFound();
-        }
     }
 
     private Dictionary<string, object?> GetData(Dictionary<string, object> body)
@@ -65,4 +104,4 @@ [FromBody] Dictionary<string, object> body
 
         return data!;
     }
-}
+}

CsharpKioskDemoDotnet/Src/Shared/Infrastructure/DependencyInjectionConfiguration.cs

@@ -60,6 +60,7 @@ public static void Execute(WebApplicationBuilder builder)
         builder.Services.AddScoped<GetInvoiceDtoGrid>();
         builder.Services.AddScoped<GetInvoiceDto>();
         builder.Services.AddScoped<UpdateInvoice>();
+        builder.Services.AddScoped<WebhookVerifier>();
 
         builder.Services
             .AddServerSentEvents<INotificationsServerSentEventsService, NotificationsServerSentEventsService>(
@@ -70,4 +71,4 @@ public static void Execute(WebApplicationBuilder builder)
                 }
             );
     }
-}
+}

CsharpKioskDemoDotnet/Src/Shared/Logger/LogCode.cs

@@ -15,7 +15,8 @@ public enum LogCode
     [Description("INVOICE_UPDATE_FAIL")] InvoiceUpdateFail,
     [Description("IPN_RECEIVED")] IpnReceived,
     [Description("IPN_VALIDATE_SUCCESS")] IpnValidateSuccess,
-    [Description("IPN_VALIDATE_FAIL")] IpnValidateFail
+    [Description("IPN_VALIDATE_FAIL")] IpnValidateFail,
+    [Description("IPN_SIGNATURE_VERIFICATION_FAIL")] IpnSignatureVerificationFail
 }
 
 public static class DescriptionAttributeExtensions
@@ -29,4 +30,4 @@ public static string GetEnumDescription(this Enum e)
 
         return descriptionAttribute!.Description;
     }
-}
+}