The webbrowser queries host services via IServiceProvider implemented on the ActiveX host. One of the services is IHttpSecurity, which can be used to override the certificate problem dialog.
Security warning: ignoring security problems can compromise your application.
IHttpSecurity is derived from IWindowForBindingUI, so the host needs to implement it too.
In Windows forms, customizing certificate error handling involves the following:
- derive a class from WebBrowser
- create a nested class derived from WebBrowser.WebBrowserSite (the only way you can derive from the nested class)
- overwrite CreateWebBrowserSiteBase and return a new instance of your webbrowser site.
- implement IServiceProvider on the webbrowser site
- implement IServiceProvider.QueryService so it returns an IHttpSecurity imepleemntation when the IHttpSecurity service is requested
- handle IHttpSecurity.OnSecurityProblem and return S_OK (warning: undocumented code, won’t work in IE6)
- use the new webbrowser in the form
Sample code:
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void webBrowser1_DocumentCompleted(object sender,
WebBrowserDocumentCompletedEventArgs e)
{
if (e.Url.ToString() == “about:blank”)
{
//create a certificate mismatch
webBrowser1.Navigate(“https://74.125.225.229”);
}
}
}
[Guid(“6D5140C1-7436-11CE-8034-00AA006009FA”)]
[InterfaceType(ComInterfaceType.InterfaceIsIUnknown)]
[ComImport]
public interface UCOMIServiceProvider
{
[return: MarshalAs(UnmanagedType.I4)]
[PreserveSig]
int QueryService(
[In] ref Guid guidService,
[In] ref Guid riid,
[Out] out IntPtr ppvObject);
}
[ComImport()]
[ComVisible(true)]
[Guid(“79eac9d5-bafa-11ce-8c82-00aa004ba90b”)]
[InterfaceTypeAttribute(ComInterfaceType.InterfaceIsIUnknown)]
public interface IWindowForBindingUI
{
[return: MarshalAs(UnmanagedType.I4)]
[PreserveSig]
int GetWindow(
[In] ref Guid rguidReason,
[In, Out] ref IntPtr phwnd);
}
[ComImport()]
[ComVisible(true)]
[Guid(“79eac9d7-bafa-11ce-8c82-00aa004ba90b”)]
[InterfaceTypeAttribute(ComInterfaceType.InterfaceIsIUnknown)]
public interface IHttpSecurity
{
//derived from IWindowForBindingUI
[return: MarshalAs(UnmanagedType.I4)]
[PreserveSig]
int GetWindow(
[In] ref Guid rguidReason,
[In, Out] ref IntPtr phwnd);
[PreserveSig]
int OnSecurityProblem(
[In, MarshalAs(UnmanagedType.U4)] uint dwProblem);
}
public class MyWebBrowser : WebBrowser
{
public static Guid IID_IHttpSecurity
= new Guid(“79eac9d7-bafa-11ce-8c82-00aa004ba90b”);
public static Guid IID_IWindowForBindingUI
= new Guid(“79eac9d5-bafa-11ce-8c82-00aa004ba90b”);
public const int S_OK = 0;
public const int S_FALSE = 1;
public const int E_NOINTERFACE = unchecked((int)0x80004002);
public const int RPC_E_RETRY = unchecked((int)0x80010109);
protected override WebBrowserSiteBase CreateWebBrowserSiteBase()
{
return new MyWebBrowserSite(this);
}
class MyWebBrowserSite : WebBrowserSite,
UCOMIServiceProvider,
IHttpSecurity,
IWindowForBindingUI
{
private MyWebBrowser myWebBrowser;
public MyWebBrowserSite(MyWebBrowser myWebBrowser)
:base(myWebBrowser)
{
this.myWebBrowser = myWebBrowser;
}
public int QueryService(ref Guid guidService
, ref Guid riid
, out IntPtr ppvObject)
{
if (riid ==IID_IHttpSecurity)
{
ppvObject= Marshal.GetComInterfaceForObject(this
, typeof(IHttpSecurity));
return S_OK;
}
if (riid == IID_IWindowForBindingUI)
{
ppvObject = Marshal.GetComInterfaceForObject(this
, typeof(IWindowForBindingUI));
return S_OK;
}
ppvObject = IntPtr.Zero;
return E_NOINTERFACE;
}
public int GetWindow(ref Guid rguidReason
, ref IntPtr phwnd)
{
if (rguidReason == IID_IHttpSecurity
|| rguidReason == IID_IWindowForBindingUI)
{
phwnd = myWebBrowser.Handle;
return S_OK;
}
else
{
phwnd = IntPtr.Zero;
return S_FALSE;
}
}
public int OnSecurityProblem(uint dwProblem)
{
//ignore errors
//undocumented return code, does not work on IE6
return S_OK;
}
}
}
For sample code in providing the service using MFC, check Handle NewWindow3 and ShowModalDialog in CHtmlView. The way to implements IHttpSecurity is similar to how the article exposes the INewWindowManager service to the webbrowser control.
Sheng Jiang 蒋晟 
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