add antiforgery header when uploading document (Azure-Samples#204)

## Purpose
<!-- Describe the intention of the changes being proposed. What problem
does it solve or functionality does it add? -->
* ...

## Does this introduce a breaking change?
<!-- Mark one with an "x". -->
```
[ ] Yes
[ ] No
```

## Pull Request Type
What kind of change does this Pull Request introduce?

<!-- Please check the one that applies to this PR using "x". -->
```
[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Documentation content changes
[ ] Other... Please describe:
```

## How to Test
*  Get the code

```
git clone [repo-address]
cd [repo-name]
git checkout [branch-name]
npm install
```

* Test the code
<!-- Add steps to run the tests suite and/or manually test -->
```
```

## What to Check
Verify that the following are valid
* ...

## Other Information
<!-- Add any other helpful information that may be needed here. -->

Author: LittleLittleCloud

app/backend/Program.cs

@@ -1,5 +1,7 @@
 // Copyright (c) Microsoft. All rights reserved.
 
+using Microsoft.AspNetCore.Antiforgery;
+
 var builder = WebApplication.CreateBuilder(args);
 
 builder.Configuration.ConfigureAzureKeyVault();
@@ -12,6 +14,7 @@
 builder.Services.AddRazorPages();
 builder.Services.AddCrossOriginResourceSharing();
 builder.Services.AddAzureServices();
+builder.Services.AddAntiforgery(options => { options.HeaderName = "X-CSRF-TOKEN-HEADER"; options.FormFieldName = "X-CSRF-TOKEN-FORM"; });
 
 if (builder.Environment.IsDevelopment())
 {
@@ -80,8 +83,17 @@
 app.UseStaticFiles();
 app.UseCors();
 app.UseBlazorFrameworkFiles();
+app.UseAntiforgery();
 app.MapRazorPages();
 app.MapControllers();
+
+app.Use(next => context =>
+{
+    var antiforgery = app.Services.GetRequiredService<IAntiforgery>();
+    var tokens = antiforgery.GetAndStoreTokens(context);
+    context.Response.Cookies.Append("XSRF-TOKEN", tokens?.RequestToken ?? string.Empty, new CookieOptions() { HttpOnly = false });
+    return next(context);
+});
 app.MapFallbackToFile("index.html");
 
 app.MapApi();

app/frontend/Pages/Docs.razor.cs

@@ -28,6 +28,9 @@ public sealed partial class Docs : IDisposable
     [Inject]
     public required ILogger<Docs> Logger { get; set; }
 
+    [Inject]
+    public required IJSRuntime JSRuntime { get; set; }
+
     private bool FilesSelected => _fileUpload is { Files.Count: > 0 };
 
     protected override void OnInitialized() =>
@@ -64,8 +67,10 @@ private async Task SubmitFilesForUploadAsync()
     {
         if (_fileUpload is { Files.Count: > 0 })
         {
+            var cookie = await JSRuntime.InvokeAsync<string>("getCookie", "XSRF-TOKEN");
+
             var result = await Client.UploadDocumentsAsync(
-                _fileUpload.Files, MaxIndividualFileSize);
+                _fileUpload.Files, MaxIndividualFileSize, cookie);
 
             Logger.LogInformation("Result: {x}", result);
 

app/frontend/Services/ApiClient.cs

@@ -26,7 +26,8 @@ public async Task<bool> ShowLogoutButtonAsync()
 
     public async Task<UploadDocumentsResponse> UploadDocumentsAsync(
         IReadOnlyList<IBrowserFile> files,
-        long maxAllowedSize)
+        long maxAllowedSize,
+        string cookie)
     {
         try
         {
@@ -42,6 +43,10 @@ public async Task<UploadDocumentsResponse> UploadDocumentsAsync(
                 content.Add(fileContent, file.Name, file.Name);
             }
 
+            // set cookie
+            content.Headers.Add("X-CSRF-TOKEN-FORM", cookie);
+            content.Headers.Add("X-CSRF-TOKEN-HEADER", cookie);
+
             var response = await httpClient.PostAsync("api/documents", content);
 
             response.EnsureSuccessStatusCode();

app/frontend/wwwroot/getCookie.js

@@ -0,0 +1,10 @@
+function getCookie(cname) {
+    var decodedCookie = decodeURIComponent(document.cookie);
+    var ca = decodedCookie.split(';');
+    for (var i = 0; i < ca.length; i++) {
+        var arr = ca[i].split('=');
+        if (arr[0] == cname)
+            return arr[1]
+    }
+    return "";
+}

app/frontend/wwwroot/index.html

@@ -35,6 +35,7 @@
     <script>navigator.serviceWorker.register('service-worker.js');</script>
     <script src="_content/MudBlazor/MudBlazor.min.js"></script>
     <script src="_content/Blazor.SpeechSynthesis.WebAssembly/blazorators.speechSynthesis.g.js"></script>
+    <script src="getCookie.js"></script>
     <script src="https://cdn.jsdelivr.net/gh/highlightjs/[email protected]/build/highlight.min.js"></script>
     <script src="https://cdn.jsdelivr.net/gh/highlightjs/[email protected]/build/languages/csharp.min.js" defer></script>
     <script src="https://cdn.jsdelivr.net/gh/highlightjs/[email protected]/build/languages/dockerfile.min.js" defer></script>