[BlazorWebView] Implement web request interception #30037

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged

rmarinho merged 29 commits into net10.0 from dev/blazorwebview-interception

Jun 23, 2025

src/BlazorWebView/src/Maui/Android/WebKitWebViewClient.cs

            
                      Original file line number
                      Diff line number
                      Diff line change
                  
    @@ -4,6 +4,8 @@
  
    using Android.Runtime;

    using Android.Webkit;

    using Java.Net;

    using Microsoft.Extensions.Logging;

    using Microsoft.Maui.Platform;

    using AWebView = Android.Webkit.WebView;

    namespace Microsoft.AspNetCore.Components.WebView.Maui

    @@ -83,10 +85,40 @@ private bool ShouldOverrideUrlLoadingCore(IWebResourceRequest? request)
  
    			}

    			var requestUri = request?.Url?.ToString();

    			var logger = _webViewHandler?.Logger;

    			logger?.LogDebug("Intercepting request for {Url}.", requestUri);

    			if (view is not null && request is not null && !string.IsNullOrEmpty(requestUri))

    			{

    				// 1. Check if the app wants to modify or override the request

    				var response = WebRequestInterceptingWebView.TryInterceptResponseStream(_webViewHandler, view, request, requestUri, logger);

    				if (response is not null)

    				{

    					return response;

    				}

    				// 2. Check if the request is for a Blazor resource

    				response = GetResponse(requestUri, _webViewHandler?.Logger);

    				if (response is not null)

    				{

    					return response;

    				}

    			}

    			// 3. Otherwise, we let the request go through as is

    			logger?.LogDebug("Request for {Url} was not handled.", requestUri);

    			return base.ShouldInterceptRequest(view, request);

    		}

    		private WebResourceResponse? GetResponse(string requestUri, ILogger? logger)

    		{

    			var allowFallbackOnHostPage = AppOriginUri.IsBaseOfPage(requestUri);

    			requestUri = QueryStringHelper.RemovePossibleQueryString(requestUri);

    			_webViewHandler?.Logger.HandlingWebRequest(requestUri);

    			logger?.HandlingWebRequest(requestUri);

    			if (requestUri != null &&

    				_webViewHandler != null &&

    @@ -95,16 +127,16 @@ private bool ShouldOverrideUrlLoadingCore(IWebResourceRequest? request)
  
    			{

    				var contentType = headers["Content-Type"];

    				_webViewHandler?.Logger.ResponseContentBeingSent(requestUri, statusCode);

    				logger?.ResponseContentBeingSent(requestUri, statusCode);

    				return new WebResourceResponse(contentType, "UTF-8", statusCode, statusMessage, headers, content);

    			}

    			else

    			{

    				_webViewHandler?.Logger.ReponseContentNotFound(requestUri ?? string.Empty);

    				logger?.ResponseContentNotFound(requestUri ?? string.Empty);

    			}

    			return base.ShouldInterceptRequest(view, request);

    			return null;

    		}

    		public override void OnPageFinished(AWebView? view, string? url)

src/BlazorWebView/src/Maui/BlazorWebView.cs

-Original file line number
+Diff line change
@@ Expand Up / @@ -3,6 +3,7 @@ @@
     using Microsoft.AspNetCore.Components.Web;
     using Microsoft.Extensions.FileProviders;
     using Microsoft.Maui.Controls;
+    using Microsoft.Maui;
     namespace Microsoft.AspNetCore.Components.WebView.Maui
     {
@@ Expand Down Expand Up / @@ -65,6 +66,18 @@ public string StartPath @@
     		/// </summary>
     		public event EventHandler<BlazorWebViewInitializedEventArgs>? BlazorWebViewInitialized;
+    		/// <summary>
+    		/// Raised when a web resource is requested. This event allows the application to intercept the request and provide a
+    		/// custom response.
+    		/// The event handler can set the <see cref="WebViewWebResourceRequestedEventArgs.Handled"/> property to true
+    		/// to indicate that the request has been handled and no further processing is needed. If the event handler does set this
+    		/// property to true, it must also call the
+    		/// <see cref="WebViewWebResourceRequestedEventArgs.SetResponse(int, string, System.Collections.Generic.IReadOnlyDictionary{string, string}?, System.IO.Stream?)"/>
+    		/// or <see cref="WebViewWebResourceRequestedEventArgs.SetResponse(int, string, System.Collections.Generic.IReadOnlyDictionary{string, string}?, System.Threading.Tasks.Task{System.IO.Stream?})"/>
+    		/// method to provide a response to the request.
+    		/// </summary>
+    		public event EventHandler<WebViewWebResourceRequestedEventArgs>? WebResourceRequested;
     		/// <inheritdoc />
     #if ANDROID
     		[System.Runtime.Versioning.SupportedOSPlatform("android23.0")]
@@ Expand Down Expand Up @@
     		/// <inheritdoc />
     		void IBlazorWebView.BlazorWebViewInitialized(BlazorWebViewInitializedEventArgs args) =>
     			BlazorWebViewInitialized?.Invoke(this, args);
+    		/// <inheritdoc />
+    		bool IWebRequestInterceptingWebView.WebResourceRequested(WebResourceRequestedEventArgs args)
+    		{
+    			var platformArgs = new PlatformWebViewWebResourceRequestedEventArgs(args);
+    			var e = new WebViewWebResourceRequestedEventArgs(platformArgs);
+    			WebResourceRequested?.Invoke(this, e);
+    			return e.Handled;
+    		}
     	}
     }

src/BlazorWebView/src/Maui/IBlazorWebView.cs

-Original file line number
+Diff line change
@@ Expand Up / @@ -8,7 +8,7 @@ namespace Microsoft.AspNetCore.Components.WebView.Maui @@
     	/// <summary>
     	/// Defines a contract for a view that renders Blazor content.
     	/// </summary>
-    	public interface IBlazorWebView : IView
+    	public interface IBlazorWebView : IView, IWebRequestInterceptingWebView
     	{
     		/// <summary>
     		/// Gets the path to the HTML file to render.
@@ Expand Down @@

src/BlazorWebView/src/Maui/Microsoft.AspNetCore.Components.WebView.Maui.csproj

-Original file line number
+Diff line change
@@ Expand Up / @@ -33,7 +33,6 @@ @@
       <ItemGroup>
         <Compile Include="..\SharedSource\**\*.cs" Link="Windows\SharedSource\%(Filename)%(Extension)" />
-        <Compile Include="..\..\..\Core\src\TaskExtensions.cs" Link="Utilities\TaskExtensions.cs" />
       </ItemGroup>
       <ItemGroup>
@@ Expand Down @@

src/BlazorWebView/src/Maui/PublicAPI/net-android/PublicAPI.Unshipped.txt

Original file line number	Diff line number	Diff line change
		@@ -1 +1,2 @@
		#nullable enable
		Microsoft.AspNetCore.Components.WebView.Maui.BlazorWebView.WebResourceRequested -> System.EventHandler<Microsoft.Maui.Controls.WebViewWebResourceRequestedEventArgs!>?

src/BlazorWebView/src/Maui/PublicAPI/net-ios/PublicAPI.Unshipped.txt

Original file line number	Diff line number	Diff line change
		@@ -1 +1,2 @@
		#nullable enable
		Microsoft.AspNetCore.Components.WebView.Maui.BlazorWebView.WebResourceRequested -> System.EventHandler<Microsoft.Maui.Controls.WebViewWebResourceRequestedEventArgs!>?

src/BlazorWebView/src/Maui/PublicAPI/net-maccatalyst/PublicAPI.Unshipped.txt

Original file line number	Diff line number	Diff line change
		@@ -1 +1,2 @@
		#nullable enable
		Microsoft.AspNetCore.Components.WebView.Maui.BlazorWebView.WebResourceRequested -> System.EventHandler<Microsoft.Maui.Controls.WebViewWebResourceRequestedEventArgs!>?

src/BlazorWebView/src/Maui/PublicAPI/net-windows/PublicAPI.Unshipped.txt

Original file line number	Diff line number	Diff line change
		@@ -1 +1,2 @@
		#nullable enable
		Microsoft.AspNetCore.Components.WebView.Maui.BlazorWebView.WebResourceRequested -> System.EventHandler<Microsoft.Maui.Controls.WebViewWebResourceRequestedEventArgs!>?

src/BlazorWebView/src/Maui/PublicAPI/net/PublicAPI.Unshipped.txt

Original file line number	Diff line number	Diff line change
		@@ -1 +1,2 @@
		#nullable enable
		Microsoft.AspNetCore.Components.WebView.Maui.BlazorWebView.WebResourceRequested -> System.EventHandler<Microsoft.Maui.Controls.WebViewWebResourceRequestedEventArgs!>?

src/BlazorWebView/src/Maui/Windows/WinUIWebViewManager.cs

-Original file line number
+Diff line change
@@ Expand Up / @@ -10,6 +10,7 @@ @@
     using Microsoft.Web.WebView2.Core;
     using Windows.ApplicationModel;
     using Windows.Storage.Streams;
+    using Microsoft.Maui.Platform;
     using WebView2Control = Microsoft.UI.Xaml.Controls.WebView2;
     namespace Microsoft.AspNetCore.Components.WebView.Maui
@@ Expand All / @@ -20,6 +21,7 @@ namespace Microsoft.AspNetCore.Components.WebView.Maui @@
     	/// </summary>
     	internal class WinUIWebViewManager : WebView2WebViewManager
     	{
+    		private readonly BlazorWebViewHandler _handler;
     		private readonly WebView2Control _webview;
     		private readonly string _hostPageRelativePath;
     		private readonly string _contentRootRelativeToAppRoot;
@@ Expand Down Expand Up / @@ -62,6 +64,7 @@ public WinUIWebViewManager( @@
     			ILogger logger)
     			: base(webview, services, dispatcher, fileProvider, jsComponents, contentRootRelativeToAppRoot, hostPagePathWithinFileProvider, webViewHandler, logger)
     		{
+    			_handler = webViewHandler;
     			_logger = logger;
     			_webview = webview;
     			_hostPageRelativePath = hostPagePathWithinFileProvider;
@@ Expand All / @@ -71,52 +74,71 @@ public WinUIWebViewManager( @@
     		/// <inheritdoc />
     		protected override async Task HandleWebResourceRequest(CoreWebView2WebResourceRequestedEventArgs eventArgs)
     		{
-    			// Unlike server-side code, we get told exactly why the browser is making the request,
-    			// so we can be smarter about fallback. We can ensure that 'fetch' requests never result
-    			// in fallback, for example.
-    			var allowFallbackOnHostPage =
-    				eventArgs.ResourceContext == CoreWebView2WebResourceContext.Document ||
-    				eventArgs.ResourceContext == CoreWebView2WebResourceContext.Other; // e.g., dev tools requesting page source
+    			var url = eventArgs.Request.Uri;
-    			// Get a deferral object so that WebView2 knows there's some async stuff going on. We call Complete() at the end of this method.
-    			using var deferral = eventArgs.GetDeferral();
+    			_logger.LogDebug("Intercepting request for {Url}.", url);
-    			var requestUri = QueryStringHelper.RemovePossibleQueryString(eventArgs.Request.Uri);
-    			_logger.HandlingWebRequest(requestUri);
-    			var uri = new Uri(requestUri);
-    			var relativePath = AppOriginUri.IsBaseOf(uri) ? AppOriginUri.MakeRelativeUri(uri).ToString() : null;
-    			// Check if the uri is _framework/blazor.modules.json is a special case as the built-in file provider
-    			// brings in a default implementation.
-    			if (relativePath != null &&
-    				string.Equals(relativePath, "_framework/blazor.modules.json", StringComparison.Ordinal) &&
-    				await TryServeFromFolderAsync(eventArgs, allowFallbackOnHostPage: false, requestUri, relativePath))
-    			{
-    				_logger.ResponseContentBeingSent(requestUri, 200);
-    			}
-    			else if (TryGetResponseContent(requestUri, allowFallbackOnHostPage, out var statusCode, out var statusMessage, out var content, out var headers)
-    				&& statusCode != 404)
+    			// 1. First check if the app wants to modify or override the request.
+    			if (WebRequestInterceptingWebView.TryInterceptResponseStream(_handler, _webview.CoreWebView2, eventArgs, url, _logger))
     			{
-    				// First, call into WebViewManager to see if it has a framework file for this request. It will
-    				// fall back to an IFileProvider, but on WinUI it's always a NullFileProvider, so that will never
-    				// return a file.
-    				var headerString = GetHeaderString(headers);
-    				_logger.ResponseContentBeingSent(requestUri, statusCode);
-    				eventArgs.Response = _coreWebView2Environment!.CreateWebResourceResponse(content.AsRandomAccessStream(), statusCode, statusMessage, headerString);
+    				return;
     			}
-    			else if (relativePath != null)
+    			// 2. If this is an app request, then assume the request is for a Blazor resource.
+    			var requestUri = QueryStringHelper.RemovePossibleQueryString(url);
+    			if (new Uri(requestUri) is Uri uri)
     			{
-    				await TryServeFromFolderAsync(
-    					eventArgs,
-    					allowFallbackOnHostPage,
-    					requestUri,
-    					relativePath);
+    				// Unlike server-side code, we get told exactly why the browser is making the request,
+    				// so we can be smarter about fallback. We can ensure that 'fetch' requests never result
+    				// in fallback, for example.
+    				var allowFallbackOnHostPage =
+    					eventArgs.ResourceContext == CoreWebView2WebResourceContext.Document ||
+    					eventArgs.ResourceContext == CoreWebView2WebResourceContext.Other; // e.g., dev tools requesting page source
+    				// Get a deferral object so that WebView2 knows there's some async stuff going on. We call Complete() at the end of this method.
+    				using var deferral = eventArgs.GetDeferral();
+    				_logger.HandlingWebRequest(requestUri);
+    				var relativePath = AppOriginUri.IsBaseOf(uri) ? AppOriginUri.MakeRelativeUri(uri).ToString() : null;
+    				// Check if the uri is _framework/blazor.modules.json is a special case as the built-in file provider
+    				// brings in a default implementation.
+    				if (relativePath != null &&
+    					string.Equals(relativePath, "_framework/blazor.modules.json", StringComparison.Ordinal) &&
+    					await TryServeFromFolderAsync(eventArgs, allowFallbackOnHostPage: false, requestUri, relativePath))
+    				{
+    					_logger.ResponseContentBeingSent(requestUri, 200);
+    				}
+    				else if (TryGetResponseContent(requestUri, allowFallbackOnHostPage, out var statusCode, out var statusMessage, out var content, out var headers)
+    					&& statusCode != 404)
+    				{
+    					// First, call into WebViewManager to see if it has a framework file for this request. It will
+    					// fall back to an IFileProvider, but on WinUI it's always a NullFileProvider, so that will never
+    					// return a file.
+    					var headerString = GetHeaderString(headers);
+    					_logger.ResponseContentBeingSent(requestUri, statusCode);
+    					eventArgs.Response = _coreWebView2Environment!.CreateWebResourceResponse(content.AsRandomAccessStream(), statusCode, statusMessage, headerString);
+    				}
+    				else if (relativePath != null)
+    				{
+    					await TryServeFromFolderAsync(
+    						eventArgs,
+    						allowFallbackOnHostPage,
+    						requestUri,
+    						relativePath);
+    				}
+    				// Notify WebView2 that the deferred (async) operation is complete and we set a response.
+    				deferral.Complete();
+    				return;
     			}
-    			// Notify WebView2 that the deferred (async) operation is complete and we set a response.
-    			deferral.Complete();
+    			// 3. If the request is not handled by the app nor is it a local source, then we let the WebView2
+    			//    handle the request as it would normally do. This means that it will try to load the resource
+    			//    from the internet or from the local cache.
+    			_logger.LogDebug("Request for {Url} was not handled.", url);
     		}
     		private async Task<bool> TryServeFromFolderAsync(
@@ Expand Down Expand Up / @@ -179,7 +201,7 @@ private async Task<bool> TryServeFromFolderAsync( @@
     			}
     			else
     			{
-    				_logger.ReponseContentNotFound(requestUri);
+    				_logger.ResponseContentNotFound(requestUri);
     			}
     			return false;
@@ Expand Down @@

src/BlazorWebView/src/Maui/iOS/BlazorWebViewHandler.iOS.cs

            
                      Original file line number
                      Diff line number
                      Diff line change
                  
    @@ -11,6 +11,7 @@
  
    using Microsoft.Maui;

    using Microsoft.Maui.Dispatching;

    using Microsoft.Maui.Handlers;

    using Microsoft.Maui.Platform;

    using UIKit;

    using WebKit;

    using RectangleF = CoreGraphics.CGRect;

    @@ -259,12 +260,29 @@ public SchemeHandler(BlazorWebViewHandler webViewHandler)
  
    			[SupportedOSPlatform("ios11.0")]

    			public void StartUrlSchemeTask(WKWebView webView, IWKUrlSchemeTask urlSchemeTask)

    			{

    				var responseBytes = GetResponseBytes(urlSchemeTask.Request.Url?.AbsoluteString ?? "", out var contentType, statusCode: out var statusCode);

    				var url = urlSchemeTask.Request.Url.AbsoluteString;

    				if (string.IsNullOrEmpty(url))

    				{

    					return;

    				}

    				var logger = _webViewHandler.Logger;

    				logger.LogDebug("Intercepting request for {Url}.", url);

    				// 1. First check if the app wants to modify or override the request.

    				if (WebRequestInterceptingWebView.TryInterceptResponseStream(_webViewHandler, webView, urlSchemeTask, url, logger))

    				{

    					return;

    				}

    				// 2. If this is an app request, then assume the request is for a Blazor resource.

    				var responseBytes = GetResponseBytes(url, out var contentType, statusCode: out var statusCode);

    				if (statusCode == 200)

    				{

    					using (var dic = new NSMutableDictionary<NSString, NSString>())

    					{

    						dic.Add((NSString)"Content-Length", (NSString)(responseBytes.Length.ToString(CultureInfo.InvariantCulture)));

    						dic.Add((NSString)"Content-Length", (NSString)responseBytes.Length.ToString(CultureInfo.InvariantCulture));

    						dic.Add((NSString)"Content-Type", (NSString)contentType);

    						// Disable local caching. This will prevent user scripts from executing correctly.

    						dic.Add((NSString)"Cache-Control", (NSString)"no-cache, max-age=0, must-revalidate, no-store");

    @@ -278,6 +296,12 @@ public void StartUrlSchemeTask(WKWebView webView, IWKUrlSchemeTask urlSchemeTask
  
    					urlSchemeTask.DidReceiveData(NSData.FromArray(responseBytes));

    					urlSchemeTask.DidFinish();

    				}

    				// 3. If the request is not handled by the app nor is it a local source, then we let the WKWebView

    				//    handle the request as it would normally do. This means that it will try to load the resource

    				//    from the internet or from the local cache.

    				logger.LogDebug("Request for {Url} was not handled.", url);

    			}

    			private byte[] GetResponseBytes(string? url, out string contentType, out int statusCode)

    @@ -303,7 +327,7 @@ private byte[] GetResponseBytes(string? url, out string contentType, out int sta
  
    				}

    				else

    				{

    					_webViewHandler?.Logger.ReponseContentNotFound(url);

    					_webViewHandler?.Logger.ResponseContentNotFound(url);

    					statusCode = 404;

    					contentType = string.Empty;

src/BlazorWebView/src/SharedSource/Log.cs

-Original file line number
+Diff line change
@@ Expand Up / @@ -24,7 +24,7 @@ internal static partial class Log @@
     	public static partial void ResponseContentBeingSent(this ILogger logger, string requestUri, int statusCode);
     	[LoggerMessage(EventId = 6, Level = LogLevel.Debug, Message = "Response content was not found for web request to URI '{requestUri}'.")]
-    	public static partial void ReponseContentNotFound(this ILogger logger, string requestUri);
+    	public static partial void ResponseContentNotFound(this ILogger logger, string requestUri);
     	[LoggerMessage(EventId = 7, Level = LogLevel.Debug, Message = "Navigation event for URI '{uri}' with URL loading strategy '{urlLoadingStrategy}'.")]
     	public static partial void NavigationEvent(this ILogger logger, Uri uri, UrlLoadingStrategy urlLoadingStrategy);
@@ Expand Down @@

src/BlazorWebView/src/SharedSource/WebView2WebViewManager.cs

            
                      Original file line number
                      Diff line number
                      Diff line change
                  
    @@ -259,7 +259,7 @@ private async Task<bool> TryInitializeWebView2()
  
    			});

    #endif

    			_webview.CoreWebView2.AddWebResourceRequestedFilter($"{AppOrigin}*", CoreWebView2WebResourceContext.All);

    			_webview.CoreWebView2.AddWebResourceRequestedFilter("*", CoreWebView2WebResourceContext.All);

    			_webview.CoreWebView2.WebResourceRequested += async (s, eventArgs) =>

    			{

    @@ -325,7 +325,7 @@ protected virtual Task HandleWebResourceRequest(CoreWebView2WebResourceRequested
  
    			}

    			else

    			{

    				_logger.ReponseContentNotFound(requestUri);

    				_logger.ResponseContentNotFound(requestUri);

    			}

    #elif WEBVIEW2_MAUI

    			// No-op here because all the work is done in the derived WinUIWebViewManager

0 ...ples/WebViewAppShared/NoOpComponent.razor → ...eviceTests/Components/NoOpComponent.razor

File renamed without changes.

0 ...les/WebViewAppShared/TestComponent1.razor → ...viceTests/Components/TestComponent1.razor

File renamed without changes.

0 ...WebViewAppShared/TestComponent1.razor.css → ...Tests/Components/TestComponent1.razor.css

File renamed without changes.

src/BlazorWebView/tests/MauiDeviceTests/Components/_Imports.razor

-Original file line number
+Diff line change
@@ -0,0 +1,5 @@
+    @using System.Net.Http
+    @using Microsoft.AspNetCore.Components.Forms
+    @using Microsoft.AspNetCore.Components.Routing
+    @using Microsoft.AspNetCore.Components.Web
+    @using Microsoft.JSInterop

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

[BlazorWebView] Implement web request interception #30037

Uh oh!

Diff view

Diff view

There are no files selected for viewing

Uh oh!

Uh oh!

Uh oh!