ASP.NET Core跨站登录重定向的实现新姿势

services.AddAuthentication()
.AddCookie(options =>
{
 options.LoginPath = "/account/signin";
});

services.AddAuthentication()
.AddCookie(options =>
{
 var originRedirectToLogin = options.Events.OnRedirectToLogin;
 options.Events.OnRedirectToLogin = context =>
 {
  return originRedirectToLogin(RebuildRedirectUri(context));
 };
});

private static RedirectContext<CookieAuthenticationOptions> RebuildRedirectUri(
 RedirectContext<CookieAuthenticationOptions> context)
{
 if (context.RedirectUri.StartsWith(ACCOUNT_SITE))
  return context;

 var originUri = new Uri(context.RedirectUri);
 var uriBuilder = new UriBuilder(ACCOUNT_SITE);
 uriBuilder.Path = originUri.AbsolutePath;
 var queryStrings = QueryHelpers.ParseQuery(originUri.Query);
 var returnUrlName = context.Options.ReturnUrlParameter;
 var returnUrl = originUri.GetComponents(UriComponents.SchemeAndServer, UriFormat.Unescaped) + queryStrings[returnUrlName];
 uriBuilder.Query = QueryString.Create(returnUrlName, returnUrl).ToString();
 context.RedirectUri = uriBuilder.ToString();
 return context;
}