Github auth started.

src/Squidex/Config/Authentication/AuthenticationServices.cs

@@ -17,6 +17,7 @@ namespace Squidex.Config.Authentication
             var identityOptions = config.GetSection("identity").Get<MyIdentityOptions>();
 
             services.AddAuthentication()
+                .AddMyExternalGithubAuthentication(identityOptions)
                 .AddMyExternalGoogleAuthentication(identityOptions)
                 .AddMyExternalMicrosoftAuthentication(identityOptions)
                 .AddMyExternalOdic(identityOptions)

src/Squidex/Config/Authentication/GithubAuthenticationServices.cs

@@ -0,0 +1,30 @@
+// ==========================================================================
+//  Squidex Headless CMS
+// ==========================================================================
+//  Copyright (c) Squidex UG (haftungsbeschränkt)
+//  All rights reserved. Licensed under the MIT license.
+// ==========================================================================
+
+using Microsoft.AspNetCore.Authentication;
+using Microsoft.Extensions.DependencyInjection;
+
+namespace Squidex.Config.Authentication
+{
+    public static class GithubAuthenticationServices
+    {
+        public static AuthenticationBuilder AddMyExternalGithubAuthentication(this AuthenticationBuilder authBuilder, MyIdentityOptions identityOptions)
+        {
+            if (identityOptions.IsGithubAuthConfigured())
+            {
+                authBuilder.AddGitHub(options =>
+                {
+                    options.ClientId = identityOptions.GithubClient;
+                    options.ClientSecret = identityOptions.GithubSecret;
+                    options.Events = new GithubHandler();
+                });
+            }
+
+            return authBuilder;
+        }
+    }
+}

src/Squidex/Config/Authentication/GithubHandler.cs

@@ -0,0 +1,46 @@
+// ==========================================================================
+//  Squidex Headless CMS
+// ==========================================================================
+//  Copyright (c) Squidex UG (haftungsbeschränkt)
+//  All rights reserved. Licensed under the MIT license.
+// ==========================================================================
+
+using System.Linq;
+using System.Security.Claims;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Authentication.OAuth;
+using Squidex.Shared.Identity;
+
+namespace Squidex.Config.Authentication
+{
+    public sealed class GithubHandler : OAuthEvents
+    {
+        public override Task CreatingTicket(OAuthCreatingTicketContext context)
+        {
+            var displayNameClaim = context.Identity.Claims.FirstOrDefault(x => x.Type == ClaimTypes.Name);
+            if (displayNameClaim != null)
+            {
+                context.Identity.SetDisplayName(displayNameClaim.Value);
+            }
+
+            var pictureUrl = context.User?.Value<string>("picture");
+
+            if (string.IsNullOrWhiteSpace(pictureUrl))
+            {
+                pictureUrl = context.User?["image"]?.Value<string>("url");
+
+                if (pictureUrl != null && pictureUrl.EndsWith("?sz=50", System.StringComparison.Ordinal))
+                {
+                    pictureUrl = pictureUrl.Substring(0, pictureUrl.Length - 6);
+                }
+            }
+
+            if (!string.IsNullOrWhiteSpace(pictureUrl))
+            {
+                context.Identity.SetPictureUrl(pictureUrl);
+            }
+
+            return base.CreatingTicket(context);
+        }
+    }
+}