Question

I have a WPF application with a WebBrowser control.

I’d like to intercept and trace the http request issued by the browser control.

I don’t want to modify the content. I only want to perform some rules when loaded urls are matching a specific pattern. Especially, I have some ajax call that are returning data that populate the web controls.

I want to capture this data to act also in the container application. Is it possible? How?

The conrtol have a LoadCompleted event, but it’s only fired for the uri specifid in the Source property, not subressourceS.

Answer 1

As answered in the duplicate, here is the solution :

I have been able to solve such issue.

You will need some 3rd party assemblies :

1. FiddlerCore: will act as a http proxy, embedded in your application
2. Awesomium.net: a WebBrowser control, that works with the chromium engine. I choose this engine, because it allows to specify a proxy server just for the application.

The idea, as you guess, is to create an in-memory proxy server, and redirect your web browser control to this proxy.

Then, FiddlerCore publishes some events where you can analyse the request/response, especially the body.

As it acts a proxy, all communications, including Ajax calls, Flash calls, etc, are routed by the proxy.

If it can help, a small code that help me to prototype this behavior:

App.cs :

/// <summary>
/// Interaction logic for App.xaml
/// </summary>
public partial class App : Application
{
    protected override void OnStartup(StartupEventArgs e)
    {
        BootStrap();
        base.OnStartup(e);
    }

    private void BootStrap()
    {
        SetupInternalProxy();
        SetupBrowser();
    }

    private static void SetupBrowser()
    {
        // We may be a new window in the same process.
        if (!WebCore.IsRunning)
        {
            // Setup WebCore with plugins enabled.
            WebCoreConfig config = new WebCoreConfig
            {
                ProxyServer = "http://127.0.0.1:" + FiddlerApplication.oProxy.ListenPort.ToString(),
                EnablePlugins = true,
                SaveCacheAndCookies = true
            };
            WebCore.Initialize(config);
        }
        else
        {
            throw new InvalidOperationException("WebCore should be already running");
        }
    }

    private void SetupInternalProxy()
    {
        FiddlerApplication.AfterSessionComplete += FiddlerApplication_AfterSessionComplete;
        FiddlerApplication.Log.OnLogString += (o, s) => Debug.WriteLine(s);

        FiddlerCoreStartupFlags oFCSF = FiddlerCoreStartupFlags.Default;
        //this line is important as it will avoid changing the proxy for the whole system.
        oFCSF = (oFCSF & ~FiddlerCoreStartupFlags.RegisterAsSystemProxy);

        FiddlerApplication.Startup(
            0,
            oFCSF
            );
    }

    private void FiddlerApplication_AfterSessionComplete(Session oSession)
    {
        Debug.WriteLine(oSession.GetResponseBodyAsString());
    }
}

MainWindow.xaml :

<Window
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="clr-namespace:WpfApplication1" 
        xmlns:Custom="http://schemas.awesomium.com/winfx" 
        x:Class="WpfApplication1.MainWindow"
        Title="MainWindow" Height="350" Width="525" Loaded="MainWindow_Loaded">
    <Grid>

        <Custom:WebControl Name="browser"/>

    </Grid>
</Window>

And finally, MainWindow.xaml.cs :

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
    }

    private void MainWindow_Loaded(object sender, RoutedEventArgs e)
    {
        browser.LoadURL("http://google.fr");
    }
}

You will have to add some plumbing to this application, in order to route and analyse the requestion from the app to the business class, but that’s beyond the scope of this question.