Add response_mode=form_post to legacy WebView authorization requests

src/client/Microsoft.Identity.Client/Platforms/Features/WinFormsLegacyWebUi/CustomWebBrowser.CustomWebBrowserEvent.cs

@@ -21,9 +21,9 @@ public CustomWebBrowserEvent(CustomWebBrowser parent)
             public void NavigateError(object pDisp, ref object url, ref object frame, ref object statusCode,
                 ref bool cancel)
             {
-                string uriString = (url == null) ? "" : ((string) url);
-                string frameString = (frame == null) ? "" : ((string) frame);
-                int statusCodeInt = (statusCode == null) ? 0 : ((int) statusCode);
+                string uriString = (url == null) ? "" : ((string)url);
+                string frameString = (frame == null) ? "" : ((string)frame);
+                int statusCodeInt = (statusCode == null) ? 0 : ((int)statusCode);
 
 #pragma warning disable 618 // WebBrowserNavigateErrorEventArgs is marked obsolete
                 WebBrowserNavigateErrorEventArgs e = new WebBrowserNavigateErrorEventArgs(uriString, frameString,
@@ -33,27 +33,19 @@ public void NavigateError(object pDisp, ref object url, ref object frame, ref ob
                 cancel = e.Cancel;
             }
 
-            // This method are empty because we agree with their implementation in base class event handler System.Windows.Forms.WebBrowser+WebBrowserEvent.
-            // We disagree with empty implementation of NavigateError.
-            // We also could tweak implementation of base class if we disagree by implementing this method.
-            // This is COM events handler, defined in COM interface, however this model works as Events in .NET
-            // Multiple handlers are possible, so empty method just called and do nothing.
-            public void BeforeNavigate2(object pDisp, ref object urlObject, ref object flags, ref object targetFrameName,
+            public void BeforeNavigate2(object pDisp, ref object url, ref object flags, ref object targetFrameName,
                 ref object postData, ref object headers, ref bool cancel)
             {
-                // TODO: Navigating event from public class could be called for internal object.
-                //       Current implementation of System.Windows.Forms.WebBrowser doesn't allow you to track who issues this event this control or IFrame,
-                //       internal IFrame will have different pDisp, so we need filter events from internal IFrames by analyzing this field:
-                //
-                //       if ( this.webBrowser.ActiveXInstance != e.WebBrowserActiveXInstance )
-                //       {
-                //           // this event came from internal frame, ignore this.
-                //           return;
-                //       }
-                //
-                //       See WindowsFormsWebAuthenticationDialogBase.WebBrowserNavigateErrorHandler( object sender, WebBrowserNavigateErrorEventArgs e )
-                //       Thus, before making any decision it will be safe to check if Navigating event comes from right object.
-                //       This not a P0 bug, as it final URL with auth code could came only in main frame, however it could give issue with more complicated logic.
+                string urlString = (url == null) ? string.Empty : ((string)url);
+                int flagsInt = (flags == null) ? 0 : ((int)flags);
+                string targetFrameNameString = (targetFrameName == null) ? string.Empty : ((string)targetFrameName);
+                byte[] postDataBytes = (byte[])postData;
+                string headersString = (headers == null) ? string.Empty : ((string)headers);
+
+                WebBrowserBeforeNavigateEventArgs e = new WebBrowserBeforeNavigateEventArgs(urlString, postDataBytes,
+                    headersString, flagsInt, targetFrameNameString, pDisp);
+                parent.OnBeforeNavigate(e);
+                cancel = e.Cancel;
             }
 
             public void ClientToHostWindow(ref long cX, ref long cY)

src/client/Microsoft.Identity.Client/Platforms/Features/WinFormsLegacyWebUi/CustomWebBrowser.cs

@@ -41,7 +41,7 @@ protected override void CreateSink()
             {
                 webBrowserEvent = new CustomWebBrowserEvent(this);
                 webBrowserEventCookie = new AxHost.ConnectionPointCookie(activeXInstance, webBrowserEvent,
-                    typeof (NativeWrapper.DWebBrowserEvents2));
+                    typeof(NativeWrapper.DWebBrowserEvents2));
             }
         }
 
@@ -66,9 +66,16 @@ protected virtual void OnNavigateError(WebBrowserNavigateErrorEventArgs e)
         }
 #pragma warning restore 618
 
+        protected virtual void OnBeforeNavigate(WebBrowserBeforeNavigateEventArgs e)
+        {
+            BeforeNavigate?.Invoke(this, e);
+        }
+
         public event WebBrowserNavigateErrorEventHandler NavigateError;
 
-        [ComVisible(true), ComDefaultInterface(typeof (NativeWrapper.IDocHostUIHandler))]
+        public event WebBrowserBeforeNavigateEventHandler BeforeNavigate;
+
+        [ComVisible(true), ComDefaultInterface(typeof(NativeWrapper.IDocHostUIHandler))]
         protected class CustomSite : WebBrowserSite, NativeWrapper.IDocHostUIHandler, ICustomQueryInterface
         {
             private const int NotImplemented = -2147467263;
@@ -85,9 +92,9 @@ public CustomSite(WebBrowser host)
             public CustomQueryInterfaceResult GetInterface(ref Guid iid, out IntPtr ppv)
             {
                 ppv = IntPtr.Zero;
-                if (iid == typeof (NativeWrapper.IDocHostUIHandler).GUID)
+                if (iid == typeof(NativeWrapper.IDocHostUIHandler).GUID)
                 {
-                    ppv = Marshal.GetComInterfaceForObject(this, typeof (NativeWrapper.IDocHostUIHandler),
+                    ppv = Marshal.GetComInterfaceForObject(this, typeof(NativeWrapper.IDocHostUIHandler),
                         CustomQueryInterfaceMode.Ignore);
                     return CustomQueryInterfaceResult.Handled;
                 }
@@ -213,8 +220,8 @@ public int TranslateAccelerator(ref NativeWrapper.MSG msg, ref Guid group, int n
                 {
                     if (ModifierKeys == Keys.Shift || ModifierKeys == Keys.Alt || ModifierKeys == Keys.Control)
                     {
-                        int num = ((int) msg.wParam) | (int) ModifierKeys;
-                        Shortcut s = (Shortcut) num;
+                        int num = ((int)msg.wParam) | (int)ModifierKeys;
+                        Shortcut s = (Shortcut)num;
                         if (shortcutDisallowedList.Contains(s))
                         {
                             return S_OK;
@@ -243,4 +250,7 @@ public int UpdateUI()
     /// </summary>
     internal delegate void WebBrowserNavigateErrorEventHandler(object sender, WebBrowserNavigateErrorEventArgs e);
 #pragma warning restore 618
+    /// <summary>
+    /// </summary>
+    internal delegate void WebBrowserBeforeNavigateEventHandler(object sender, WebBrowserBeforeNavigateEventArgs e);
 }

src/client/Microsoft.Identity.Client/Platforms/Features/WinFormsLegacyWebUi/SilentWindowsFormsAuthenticationDialog.cs

@@ -47,13 +47,13 @@ public void CloseBrowser()
         /// </summary>
         private void SuppressBrowserSubDialogs()
         {
-            var webBrowser2 = (NativeWrapper.IWebBrowser2) WebBrowser.ActiveXInstance;
+            var webBrowser2 = (NativeWrapper.IWebBrowser2)WebBrowser.ActiveXInstance;
             webBrowser2.Silent = true;
         }
 
         /// <summary>
         /// </summary>
-        protected override void WebBrowserNavigatingHandler(object sender, WebBrowserNavigatingEventArgs e)
+        protected override void WebBrowserBeforeNavigateHandler(object sender, WebBrowserBeforeNavigateEventArgs e)
         {
             if (null == timer)
             {
@@ -73,12 +73,12 @@ protected override void WebBrowserNavigatingHandler(object sender, WebBrowserNav
             // Reset the expiry time so that it isn't relevant until the next document complete.
             navigationExpiry = DateTime.MaxValue;
 
-            base.WebBrowserNavigatingHandler(sender, e);
+            base.WebBrowserBeforeNavigateHandler(sender, e);
         }
 
         private static Timer CreateStartedTimer(Action onTickAction, int interval)
         {
-            Timer timer = new Timer {Interval = interval};
+            Timer timer = new Timer { Interval = interval };
             timer.Tick += (notUsedsender, notUsedEventArgs) => onTickAction();
             timer.Start();
             return timer;

src/client/Microsoft.Identity.Client/Platforms/Features/WinFormsLegacyWebUi/WebBrowserBeforeNavigateEventArgs.cs

@@ -0,0 +1,50 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT License.
+
+using System.ComponentModel;
+
+namespace Microsoft.Identity.Client.Platforms.Features.WinFormsLegacyWebUi
+{
+    /// <summary>
+    /// Event arguments for <c>BeforeNavigate</c> event
+    /// </summary>
+    public class WebBrowserBeforeNavigateEventArgs : CancelEventArgs
+    {
+        /// <summary>
+        /// </summary>
+        public WebBrowserBeforeNavigateEventArgs(string url, byte[] postData, string headers, int flags,
+            string targetFrameName, object webBrowserActiveXInstance)
+        {
+            Url = url;
+            PostData = postData;
+            Headers = headers;
+            Flags = flags;
+            TargetFrameName = targetFrameName;
+            WebBrowserActiveXInstance = webBrowserActiveXInstance;
+        }
+
+        /// <summary>
+        /// </summary>
+        public string Url { get; }
+
+        /// <summary>
+        /// </summary>
+        public byte[] PostData { get; }
+
+        /// <summary>
+        /// </summary>
+        public string Headers { get; }
+
+        /// <summary>
+        /// </summary>
+        public int Flags { get; }
+
+        /// <summary>
+        /// </summary>
+        public string TargetFrameName { get; }
+
+        /// <summary>
+        /// </summary>
+        public object WebBrowserActiveXInstance { get; }
+    }
+}

src/client/Microsoft.Identity.Client/Platforms/Features/WinFormsLegacyWebUi/WebBrowserNavigateErrorEventArgs.cs

@@ -24,7 +24,7 @@ public WebBrowserNavigateErrorEventArgs(string url, string targetFrameName, int
         /// </summary>
         public string TargetFrameName { get; }
 
-        // url as a string, as in case of error it could be invalid url
+        // URL as a string, as in case of error it could be invalid URL
         /// <summary>
         /// </summary>
         public string Url { get; }

src/client/Microsoft.Identity.Client/Platforms/Features/WinFormsLegacyWebUi/WebUI.cs

@@ -2,13 +2,13 @@
 // Licensed under the MIT License.
 
 using System;
-using System.Net.NetworkInformation;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.Identity.Client.Http;
 using Microsoft.Identity.Client.Internal;
 using Microsoft.Identity.Client.Platforms.Features.DesktopOs;
 using Microsoft.Identity.Client.UI;
+using Microsoft.Identity.Client.Utils;
 
 namespace Microsoft.Identity.Client.Platforms.Features.WinFormsLegacyWebUi
 {
@@ -29,6 +29,10 @@ public async Task<AuthorizationResult> AcquireAuthorizationAsync(
         {
             AuthorizationResult authorizationResult = null;
 
+            var authUriBuilder = new UriBuilder(authorizationUri);
+            authUriBuilder.AppendOrReplaceQueryParameter("response_mode", "form_post");
+            authorizationUri = authUriBuilder.Uri;
+
             var sendAuthorizeRequest = new Action(() =>
             {
                 authorizationResult = Authenticate(authorizationUri, redirectUri);

src/client/Microsoft.Identity.Client/Platforms/Features/WinFormsLegacyWebUi/WindowsFormsWebAuthenticationDialog.cs

@@ -63,10 +63,10 @@ public void ShowBrowser()
 
         /// <summary>
         /// </summary>
-        protected override void WebBrowserNavigatingHandler(object sender, WebBrowserNavigatingEventArgs e)
+        protected override void WebBrowserBeforeNavigateHandler(object sender, WebBrowserBeforeNavigateEventArgs e)
         {
             SetBrowserZoom();
-            base.WebBrowserNavigatingHandler(sender, e);
+            base.WebBrowserBeforeNavigateHandler(sender, e);
         }
 
         /// <summary>

src/client/Microsoft.Identity.Client/Platforms/Features/WinFormsLegacyWebUi/WindowsFormsWebAuthenticationDialogBase.cs

@@ -94,7 +94,7 @@ private void WebBrowser_PreviewKeyDown(object sender, PreviewKeyDownEventArgs e)
 
         /// <summary>
         /// </summary>
-        protected virtual void WebBrowserNavigatingHandler(object sender, WebBrowserNavigatingEventArgs e)
+        protected virtual void WebBrowserBeforeNavigateHandler(object sender, WebBrowserBeforeNavigateEventArgs e)
         {
             if (DialogResult == DialogResult.OK)
             {
@@ -117,24 +117,33 @@ protected virtual void WebBrowserNavigatingHandler(object sender, WebBrowserNavi
                 e.Cancel = true;
             }
 
+            if (string.IsNullOrEmpty(e.Url))
+            {
+                RequestContext.Logger.Verbose("[Legacy WebView] URL in BeforeNavigate is null or empty.");
+                e.Cancel = true;
+                return;
+            }
+
+            Uri url = new Uri(e.Url);
+
             // we cancel further processing, if we reached final URL.
             // Security issue: we prohibit navigation with auth code
-            // if redirect URI is URN, then we prohibit navigation, to prevent random browser popup.
-            e.Cancel = CheckForClosingUrl(e.Url);
+            // if redirect URI is URN, then we prohibit navigation, to prevent random browser pop-up.
+            e.Cancel = CheckForClosingUrl(url, e.PostData);
 
-            // check if the url scheme is of type browser-install://
+            // check if the URL scheme is of type browser-install://
             // this means we need to launch external browser
-            if (e.Url.Scheme.Equals("browser", StringComparison.OrdinalIgnoreCase))
+            if (url.Scheme.Equals("browser", StringComparison.OrdinalIgnoreCase))
             {
-                Process.Start(e.Url.AbsoluteUri.Replace("browser://", "https://"));
+                Process.Start(url.AbsoluteUri.Replace("browser://", "https://"));
                 e.Cancel = true;
             }
 
             if (!e.Cancel)
             {
                 string urlDecode = CoreHelpers.UrlDecode(e.Url.ToString());
                 RequestContext.Logger.VerbosePii(
-                    string.Format(CultureInfo.InvariantCulture, "Navigating to '{0}'.", urlDecode),
+                    string.Format(CultureInfo.InvariantCulture, "[Legacy WebView] Navigating to '{0}'.", urlDecode),
                     string.Empty);
             }
         }
@@ -149,7 +158,7 @@ private void WebBrowserNavigatedHandler(object sender, WebBrowserNavigatedEventA
 
             string urlDecode = CoreHelpers.UrlDecode(e.Url.ToString());
             RequestContext.Logger.VerbosePii(
-                string.Format(CultureInfo.InvariantCulture, "Navigated to '{0}'.", urlDecode),
+                string.Format(CultureInfo.InvariantCulture, "[Legacy WebView] Navigated to '{0}'.", urlDecode),
                 string.Empty);
         }
 
@@ -188,23 +197,23 @@ protected virtual void WebBrowserNavigateErrorHandler(object sender, WebBrowserN
             OnNavigationCanceled(e.StatusCode);
         }
 
-        private bool CheckForClosingUrl(Uri url)
+        private bool CheckForClosingUrl(Uri url, byte[] postData = null)
         {
             bool readyToClose = false;
 
             if (url.Authority.Equals(_desiredCallbackUri.Authority, StringComparison.OrdinalIgnoreCase) &&
                 url.AbsolutePath.Equals(_desiredCallbackUri.AbsolutePath))
             {
-                RequestContext.Logger.Info("Redirect Uri was reached. Stopping webview navigation...");
-                Result = AuthorizationResult.FromUri(url.OriginalString);
+                RequestContext.Logger.Info("[Legacy WebView] Redirect URI was reached. Stopping WebView navigation...");
+                Result = AuthorizationResult.FromPostData(postData);
                 readyToClose = true;
             }
 
             if (!readyToClose && !url.Scheme.Equals("https", StringComparison.OrdinalIgnoreCase) &&
                 !url.AbsoluteUri.Equals("about:blank", StringComparison.OrdinalIgnoreCase) && !url.Scheme.Equals("javascript", StringComparison.OrdinalIgnoreCase))
             {
                 RequestContext.Logger.Error(string.Format(CultureInfo.InvariantCulture,
-                    "Redirection to non-HTTPS scheme ({0}) found! Webview will fail...", url.Scheme));
+                    "[Legacy WebView] Redirection to non-HTTPS scheme ({0}) found! WebView will fail...", url.Scheme));
                 Result = AuthorizationResult.FromStatus(
                     AuthorizationStatus.ErrorHttp,
                     MsalError.NonHttpsRedirectNotSupported,
@@ -233,14 +242,14 @@ private void StopWebBrowser()
                 }
 
                 RequestContext.Logger.Verbose(string.Format(CultureInfo.InvariantCulture,
-                    "WebBrowser state: IsBusy: {0}, ReadyState: {1}, Created: {2}, Disposing: {3}, IsDisposed: {4}, IsOffline: {5}",
+                    "[Legacy WebView] WebBrowser state: IsBusy: {0}, ReadyState: {1}, Created: {2}, Disposing: {3}, IsDisposed: {4}, IsOffline: {5}",
                     _webBrowser.IsBusy, _webBrowser.ReadyState, _webBrowser.Created,
                     _webBrowser.Disposing, _webBrowser.IsDisposed, _webBrowser.IsOffline));
 
                 _webBrowser.Stop();
 
                 RequestContext.Logger.Verbose(string.Format(CultureInfo.InvariantCulture,
-                    "WebBrowser state (after Stop): IsBusy: {0}, ReadyState: {1}, Created: {2}, Disposing: {3}, IsDisposed: {4}, IsOffline: {5}",
+                    "[Legacy WebView] WebBrowser state (after Stop): IsBusy: {0}, ReadyState: {1}, Created: {2}, Disposing: {3}, IsDisposed: {4}, IsOffline: {5}",
                     _webBrowser.IsBusy, _webBrowser.ReadyState, _webBrowser.Created,
                     _webBrowser.Disposing, _webBrowser.IsDisposed, _webBrowser.IsOffline));
             });
@@ -262,7 +271,7 @@ internal AuthorizationResult AuthenticateAAD(Uri requestUri, Uri callbackUri)
             // The WebBrowser event handlers must not throw exceptions.
             // If they do then they may be swallowed by the native
             // browser com control.
-            _webBrowser.Navigating += WebBrowserNavigatingHandler;
+            _webBrowser.BeforeNavigate += WebBrowserBeforeNavigateHandler;
             _webBrowser.Navigated += WebBrowserNavigatedHandler;
             _webBrowser.NavigateError += WebBrowserNavigateErrorHandler;
 
@@ -285,7 +294,7 @@ protected virtual void OnAuthenticate()
         /// <param name="action"></param>
         protected void InvokeHandlingOwnerWindow(Action action)
         {
-            // We only support WindowsForms (since our dialog is winforms based)
+            // We only support Windows Forms (since our dialog is Windows Forms based)
             if (ownerWindow != null && ownerWindow is Control winFormsControl)
             {
                 winFormsControl.Invoke(action);
@@ -381,7 +390,7 @@ protected MsalClientException CreateExceptionForAuthenticationUiFailed(int statu
             string messageUnknown = string.Format(CultureInfo.InvariantCulture, formatUnknown, statusCode);
             return new MsalClientException(MsalError.AuthenticationUiFailedError, messageUnknown);
         }
-     
+
         /// <summary>
         /// </summary>
         internal static class NativeMethods