Start adding the ability to intercept all requests

[mattleibow]

Description of Change

Intercepting requests before they leave the browser will allow for the addition of headers as well as cancellation of the requests.

The API is only really fully shapeable once all the platforms are complete as each platform is really different, but the idea I have right now is a mix of all the platforms.

// NOTE: all names are random to allow for faster coding
// as we already know I can't come up with good names
// so hopefully you all can!

// This event will appear on all 3 web view controls
class WebView {
    public event EventHandler<AboutToSendRequestEventArgs> AboutToSendRequest;
}

// Cross-platform event args in order to do basic operations
class AboutToSendRequestEventArgs : EventArgs {
    // access to the platiorm args if needed
    public AboutToSendRequestEventArgsPlatformEventArgs PlatformArgs { get; }

    // some useful properties
    public Uri RequestUrl { get; }
    public IDictionary<string, string> Headers { get; } // maybe this is a wrapper type around the Request

    // the ability to cancel a request
    public bool Cancel { get; set; }

    // the ability to set a response instead of the default response
    public void SetResponse(int statusCode, IDictionary<string, string> headers, Stream contentStream);
    // could also be some custom type with GetStreamAsync() methods
    public void SetResponse(IResponseOfSomeSort respose);

    // maybe
    public IRequestOfSomeSort Request { get; }

    // or maybe some helpers
    public void SetHeaderValue(string header, string value);
}

// Platform-specific event args that allows direct access to the event that is happening
class AboutToSendRequestEventArgsPlatformEventArgs {
#if WINDOWS
    public WebView2 Sender { get; }
    public WebView2WebResourceRequestEventArgs WebResourceRequestEventArgs { get; }
#elif ...
#endif
}

Usage would be something like:

// 1. providing custom response
webView.RequestHappening += (sender, e) => {
    if (e.Request.Url == "https://myapp.com/some/endpoint?with=query&string=values") {
      e.Response = GetResponse();
    }
};

// 2. adding headers
webView.RequestHappening += (sender, e) => {
    if (e.Request.Url == "https://myapp.com/some/endpoint?with=query&string=values") {
      e.Request.Headers.Add("Header", "Value");
    }
};

// 3. cancelling requests
webView.RequestHappening += (sender, e) => {
    if (e.Request.Url == "https://myapp.com/some/endpoint?with=query&string=values") {
      e.Cancel = true;
    }
};

Tasks

• WebView
  • Android
  • iOS/macOS
  • Windows
• HybridWebView
  • Android
  • iOS/macOS
  • Windows
• BlazorWebView
  • Android
  • iOS/macOS
  • Windows

Issues Fixed

Fixes #11382

[Copilot]

Copilot reviewed 5 out of 6 changed files in this pull request and generated no comments.

Files not reviewed (1)

• src/Controls/tests/DeviceTests/Resources/Raw/HybridTestRoot/index.html: Language not supported

Comments suppressed due to low confidence (2)

src/Core/src/Handlers/HybridWebView/HybridWebViewHandler.Windows.cs:241

• Switching to a universal filter '*' may intercept more requests than intended, including external resources. Consider verifying that this change does not introduce performance impacts or unintended side effects.

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

src/Controls/samples/Controls.Sample/Pages/Controls/HybridWebViewPage.xaml.cs:22

• [nitpick] The string literal 'badthing' is used directly in the condition; consider extracting it into a named constant to improve readability and ensure consistency.

if (e.PlatformArgs.WebResourceRequestedEventArgs.Request.Uri.Contains("badthing", StringComparison.InvariantCultureIgnoreCase))

[mattleibow]

Maybe if we land this, we won't need a "proxy" endpoint as all endpoints will become proxy-able: #25867